Industrial Products – Zhenhua Zhou, Heiko Weiner, Radmila Wollrab, Celanese International Corp
Abstract for “Hydrogenation catalysts using cobalt-modified support”
“The invention concerns catalysts, processes for making catalysts, and chemical processes that employ such catalysts. Preferably, the catalysts are used to convert acetic acid into ethanol. The catalyst consists of a precious metal, one or more active metals, and a modified support made up of cobalt.
Background for “Hydrogenation catalysts using cobalt-modified support”
The conventional production of ethanol for industrial use comes from petrochemical feedstocks such as oil, natural gases, and coal. It can also be made from feed stock intermediates such as syngas or starchy materials or cellulosic material such as corn or sugarcane. There are several conventional methods to produce ethanol from petrochemical feedstocks, including direct alcohol synthesis and methanol homologation. The volatility in petrochemical feed stocks prices causes fluctuations in conventionally produced ethanol’s cost. This makes it more difficult to find alternative sources of ethanol production when feed stock prices increase. Fermentation is used to convert starchy and cellulosic materials into ethanol. However, fermentation is used for the production of ethanol for human consumption or as fuel. The fermentation of cellulosic or starchy materials can also compete with food sources, limiting the amount of ethanol available for industrial use.
“Ethanol production by the reduction of alkanoic acid and/or other carbonyl-group-containing compounds has been extensively studied and many combinations of catalysts and supports have been described in the literature. EP0175558, and U.S. Patent. have proposed the reduction of various carboxylic acid over metal oxides. No. 4,398,039. Yokoyama, et.al., ‘Carboxylic acid and derivatives?, summarizes some of the development efforts in hydrogenation catalysts for various carboxylic acid conversions. Fine Chemicals Through HeterogeneousCatalysis 2001, 370-379.
“U.S. Pat. No. 8.080.694 is a description of a process to hydrogenate alkanoic acids. It involves passing a gaseous stream consisting hydrogen and an acid in the vapor stage over a hydrogenation catalyst comprising: A platinum group metal chosen from the group consisting mainly of palladium, platinum, rhenium, and combinations thereof; and a metallic promoter selected from the silicaceous supports consisting of WO3, MoO3, Fe2O3, and Cr2O3
“U.S. Pat. No. No. 6,495,730 describes a method for hydrogenating carboxylic acids using a catalyst consisting of activated carbon to support active metallic species such as ruthenium or tin. U.S. Pat. No. 6,204,417 describes another method for making aliphatic alcohols. This involves hydrogenating aliphatic carbonoxylic acids or anhydrides of esters thereof or lactones in presence of a catalyst consisting of Pt and Res. U.S. Pat. No. No. 5,149,680 describes a method for catalytic hydrogenation, which converts carboxylic acids to their anhydrides into alcohols and/or ester in the presence a catalyst containing a Group VIII metallic, such as palladium. This metal is capable of alloying with at least one of the Group VIII metals, rhenium, or tungsten. U.S. Pat. No. 4,777,303 describes a method for producing alcohols through the hydrogenation carboxylic acid in the presence a catalyst. The first component is either molybdenum/tungsten while the second component is a noble metal from Group VIII on high-surface area graphitized carbon. U.S. Pat. No. No. 4,804,791 describes another method for producing alcohols by hydrogenation of carboxylic acid in the presence a catalyst consisting of a noble metal from Group VIII or rhenium. U.S. Pat. No. No.
“The existing processes are not commercially viable because they lack the required selectivity for ethanol.
“A first embodiment of the invention relates to a catalyst that includes a precious metal and one (or more) active metals on a modified supporting. One embodiment of the modified support includes (i) support material, (ii), cobalt, and (iii), a support modifier that contains a metal from the group comprising vanadium, tungsten and tantalum. Modified support can contain from 0.5 to 20 wt. % cobalt, and a support modifier ranging from 0.1 to 40 Wt. Based on the total weight the catalyst, %. The modified support should not contain the precious metal or any of the active metals, especially tin.
“The precious metal is chosen from the group consisting rhenium (ruthenium), platinum, palladium and osmium as well as rhenium (rhenium), ruthenium), ruthenium (ruthenium), tin, nickel, zinc, manganese, cerium, iridium, and gold. One or more active elements are chosen from the group that includes copper, iron vanadium and nickel, as well as zinc, chromium and molybdenum. Preferably the precious metal is platinum, and the active metal is Tin. The amount of precious metal that may be present can range from 0.05 to 10 Wt. % and one or more active elements may be present in amounts between 0.1 and 20 wt. Based on the total weight, the percentage is %.
The support is preferred to be a silicaceous, e.g. silica, or carbon support (e.g. carbon black or activated charcoal), but any number of supports can be used. The support can be made from silica/alumina or titania, silica/alumina and calcium metasilicate. You can find tungsten in many forms as support modifiers, including tungsten oxide or tungstate of an active metal. The support modifier metal could include cobalt-tungstate, for example.
“Another embodiment of the invention is directed towards a synthesis process that comprises the following steps: (a) impregnating a support support material with a Cobalt precursor, support modifier precursor, to form first impregnated supports; (b) heating first impregnated supports to a first temperature in order to form modified support; (c), impregnating modified support with a secondary mixed precursor to form second impregnated supports; (d) heating second impregnated supports to a modified to create the catalyst, with at least one metal; provided that the precious and at least one metal are not cobalt.
“In a second embodiment the invention is directed at a catalyst consisting of a precious metal, at least one activate metal, and a modified support. The modified support comprises: (i) support material and (iii) cobalt-tungstate. One embodiment of the modified support also includes tungsten oxide. The modified support should be substantially free from tin. You can choose at least one of the following active metals: copper, iron vanadium or nickel, zinc, chromium and molybdenum; tungsten; tin; lanthanum, cerium or manganese.
“In a third embodiment of the invention, hydrogenation catalyst comprises a precious metal and support including cobalt. The catalyst has, after calcination a x-ray difffraction pattern substantially like that shown in Table 4. The hydrogenation catalyst should consist of a precious metal from the group consisting rhenium or ruthenium, palladium, platinum, osmium and iridium. It may also include at least one active element on a modified support. This means that the at least one active material is chosen from the following: copper, iron cobalt, vanadium and nickel; tungsten; tin; lanthanum and cerium; and zinc. A modified support could include a support material and cobalt-tungstate.
“Catalyst Composition”
The present invention relates to catalyst compositions which are suitable for hydrogenation catalysts and to processes for forming them, as well as chemical processes that employ such catalysts. Preferably, the catalysts comprise one or more active elements on a support. These catalysts may be useful in catalyzing hydrogenation of a carboxylic acids, e.g. acetic acid and/or its esters, such as ethyl alcohol.
“In one embodiment, an inventive catalyst consists of a precious metal and one to three active metals on a modified supporting. Preferably the precious metal and one of the active metals is not cobalt. Modified support includes a support material and a modifier that contains a metal from tungsten to vanadium to niobium. One aspect of the modified supports also includes cobalt. Modified support does not include any metals, such as any precious metal or one or more active, that have been added to the modified support. Copper, for example, is not added to modified support if it is an active metal. Cobalt, along with any precious metals and active metals, is not allowed to be deposited on modified supports. It is understood that cobalt is calcined onto the support material after the support modifier and cobalt are calcined.
It has been found that these catalysts can be used as multifunctional hydrogenation catalysts, capable of converting both carboxylic acid (e.g., Acetic Acid) and esters thereof to their corresponding alcohol(s), such as ethanol, under hydrogenation conditions. In another embodiment, the inventive catalyst includes a precious metal and an activate metal on a modified supporting. The catalyst is capable of converting acetic acids greater than 20%, greater that 75%, or greater then 90% and ethyl-acetate to ethanol more than 0%, 10%, or 20%.
“Precious Metals and Active Metals”
“The invention’s catalysts should contain at least one precious metal impregnated on the support. You can choose from rhodium or ruthenium, gold, platinum, palladium and osmium as the precious metal. The precious metal must be a metal other that cobalt for the purposes of the invention. The preferred precious metals to be used as catalysts in the invention are palladium and platinum. Preferably, the precious metal is active in hydrogenation of a carboxylic acids and/or its ester(s) to the corresponding alcohol(s). The precious metal can be either in its elemental or molecular form. These precious metals are not included in the catalyst. %, e.g. less than 3 Wt. %, less that 2 wt. %, less that 1 wt. %, less than 1 wt. %. The range of the precious metal that may be included in the catalyst is between 0.05 and 10 wt. %, e.g. From 0.1 to 5 Wt. % or from 0.1- 3 wt. Based on the total weight the catalyst, % In some cases, the precious metal’s metal loading may be lower than that of one or more active metals.
“In addition to the precious, the catalyst also includes one or more active elements disposed on the modified support. The present invention defines the one or more active elements as a metal other that cobalt. Cobalt, when it is part of the modified supports, may disperse any support modifier metal or oxide. When cobalt is added to the modified supports, it will be calcined on the support before the introduction or impregnation of the precious metal to that support.
“Active metals” can be used to refer to catalytically-active metals that increase the conversion, selectivity, and/or productivity. They may also include precious or nonprecious active elements. A catalyst that includes a precious metal and an activate metal can include (i) one or more precious metals and one or more non-precious metal active metals, (ii), two (or even more) precious metallics. As exemplary active metals, precious metals will be included in this document. It should also be noted that the term “active metal” is not intended to suggest that any particular metal is an active one. “Active metal” is used to describe some metals that are included in the invention’s catalysts. However, this does not imply that the precious metal in these catalysts is not catalytically activated.”
“In one embodiment, one or more active metals are included in the catalyst. They can be selected from the group consisting primarily of copper, iron vanadium and nickel, as well as tungsten and tin. One embodiment does not contain cobalt. One or more active metals are not to include precious metals. They include copper, iron vanadium and nickel, as well as zinc, chromium and molybdenum. The active metals can be selected from the group comprising copper, iron, zinc, chromium and tin. One embodiment may include tin mixed with at least one active metal. One or more active metals can be either in elemental or molecular form, e.g. an oxide of the active material, or a combination thereof.
“The weight of all active metals in the catalyst, including the precious metal mentioned, should be between 0.1 and 25 wt. %, e.g. from 0.5 to 15. wt. % or from 1.0-10 wt. %. One embodiment of the catalyst could contain cobalt in amounts ranging from 0.5 to 20 wt. %, and tin from 0.5 to 20wt. %. Modified support may be used to dispose of active metals. Weight percent, except where indicated otherwise, is calculated based on the total catalyst weight, including support.
“Some embodiments of the catalyst contain at least two active metals along with the precious metal. You can choose from any of these active metals, provided they are not identical to the precious metal. In some embodiments, additional active metals can also be used. In some embodiments, additional active metals may also be used on the support.
For some examples of bimetallic (precious/active metal+precious metal) combinations, these include platinum/ruthenium and platinum/ruthenium. Some embodiments of the catalyst include three metals on a support. For example, one precious metal and two metals. Exemplary tertiary combinations may include palladium/rhenium/tin, palladium/rhenium/nickel, platinum/tin/palladium, platinum/tin/rhodium, platinum/tin/gold, platinum/tin/iridium, platinum/tin/copper, platinum/tin/chromium, platinum/tin/zinc, platinum/tin/nickel, rhodium/nickel/tin, and rhodium/iron/tin. One preferred embodiment of the tertiary mixture at least contains tin. Some embodiments of the catalyst can contain more than three metals on a support.
“When the catalyst consists of a precious metal and one activate metal on a support the active metal is present at a level from 0.1 to 20 Wt. %, e.g. from 0.1-10 wt. % or from 0.1 up to 7.5 wt. %. If the catalyst contains two or more active elements in addition to the precious, such as a first and second active metals, the first metal can be present in the catalyst in amounts ranging from 0.05 to 20 Wt. %, e.g. From 0.1 to 10 wt. % or 0.5 to 5 Wt. %. The amount of the second active metal could be anywhere from 0.05 to 5 Wt. %, e.g. from 0.1 to 3.0 wt. % or 0.5 to 2.5 wt. %. One embodiment allows for a metal loading of less than 3 wt. when the second active element is tin. %, e.g. less than 2.5 wt. %, or less than 1.5 Wt. %. A catalyst with lower tin concentrations could have a longer lifetime, but this is not a limitation of theory. One embodiment of this invention states that the metal loading for the active metals is lower than the cobalt metal loading added to the modified support.
“In some embodiments, the catalyst may also contain a third active element. The third active metal can be present in amounts ranging from 0.05 to 20 Wt. %, e.g. from 0.05 to 7.5 wt. % or 0.05 to 7.5% wt. %. Active metals can be combined or separated.
“The preferred metal ratios can vary depending on the catalyst’s active metals. Some embodiments have a mole ratio between the precious metal and one or more active elements that ranges from 10:1-10:10. This could be, for example, from 1:1 to 1:4, 2:1 to 1:2, or 1.5:1-1:10. Another embodiment may contain the precious metal in a range of 0.1 to 5 weight. %, the first and second active metals in an amount of 0.5 to 20 Wt. %, the second active metal in an amounts of 0.5 to 20wt. Based on the catalyst’s total weight, %. Another embodiment of the precious metal contains a range from 0.1 to 5 Wt. %, the first and second active metals in an amount of 0.5 to 15 Wt. % and the second metal active in an amount of 0.5 to 15 Wt. %.”
“In another embodiment, cobalt can be added to the support material and then calcined as part the modified support. Tin is then subsequently added to this modified support. It is preferable to have a cobalt-tin ratio greater than 4:1. The multifunctionality of the catalyst may be enhanced by excess cobalt based on the molar ratio to tin.
“Support Materials”
“Catalysts according to the invention require a support material. Preferably, it should be modified. One embodiment may use an inorganic or organic oxide as the support material. One embodiment of the support material can be chosen from the following: silica/alumina; titania; silica/alumina; pyrogenic silica; high purity silica. zirconia. Carbon (e.g. carbon black or activated charcoal), zeolites, and combinations thereof. The support material should consist of silica, high purity silica or pyrogenic silica. One embodiment of the silicaceous supports material is free from alkaline earth metals such as calcium and magnesium. Preferable embodiments have the support material in a range of 25 to 99 wt. % to 99 Wt. %, e.g. from 30 wt. % to 98 Wt. % to 98 wt. % to 95 Wt. Based on the total weight the catalyst.
Preferable embodiments include a silicaceous supporting material, e.g. silica, with a surface area at least 50m2/g. The silicaceous support material should have a surface area of 50 to 600m2/g. This could be between 100 and 500 m2/g or 100 to 300m2/g. As used in the application, high surface area silica refers to silica with a minimum surface area of 250 m2/g. The present specification uses the term surface area to refer to BET nitrogen surface areas. This is the total surface area as per ASTM D6556-04. It is also incorporated by reference.
The preferred silicaceous support material should also have a pore size of 5 to 100nm, e.g. from 5-30 nm to 25 nm to 5-10 nm to 5-10 nm as determined using mercury intrusion porometry. It should also have a pore volume of 0.5 to 2.0 cm3/g. This corresponds to 0.7 to 1.5 cm3/g and 0.8 to1.3 cm3/g as determined via mercury intrusion perometry.
“The morphology and composition of the catalyst may differ widely. Some exemplary embodiments may use a variety of morphologies for the support material and/or the catalyst composition, including extrudates, spheres or spray dried microspheres. The silicaceous support material should have a morphology that permits for a packing density of 0.1 to 1.05 g/cm3, or 0.3 to 0.88 g/cm3. The silica support material should have an average particle size. This is the average size of spherical and non-spherical particles. It can range from 0.01 to 1.01 cm. The support generally contains very small metal (or metallic oxide) particles or crystallites. This should not have a significant impact on the size and shape of the catalyst particles. The above mentioned particle sizes are generally applicable to both the size and final catalyst particles. However, catalyst particles can be processed to make larger catalyst particles (e.g. extruded to create catalyst pellets).
“Support Modifiers”
A support modifier is a component of the support material. The support modifier can adjust the acidity of the supporting material. A support modifier may be any metal from the following group: tungsten, molybdenum vanadium, vanadium and niobium. An oxide of the metal may be used as a support modifier. The support modifiers may be present in a range of 0.1 to 50 wt. % to 50 Wt. %, e.g. from 0.2 wt. % to 25 Wt. %, starting at 0.5 wt. % to 20 Wt. % or 1 wt. % to 15% wt. Based on the total weight the catalyst. The support modifier can be present in amounts ranging from 0.1 to 40 weights if it contains vanadium, molybdenum and tungsten. %, e.g. from 0.1 to 30% wt. %, or between 0.1 and 20 wt. Based on the total weight, %
“In some embodiments, the support moderator may be an acidic modification that increases the acidity the catalyst. You can choose from the following group of acidic support modifiers: oxides in Group IVB, oxides in Group VB, oxides in Group VIB, oxides within Group VIIB, oxides within Group VIII, aluminum oxides and combinations thereof. One embodiment of the support modifier includes metal from the group consisting tungsten, molybdenum vanadium and niobium. Preferably, the support modifier is metal chosen from the group consisting tungsten, vanadium and tantalum. The support modifier should not contain phosphorous and not be made from a precursor containing phosphorous.
“In one embodiment, acidic modifiers may also include those from the group consisting WO3, MoO3, W49O119, W50O148 and W18O49. You can also use reduced tungsten oxides and molybdenum dioxides, such as W20O58 or W49O119 or W50O148 or W18O49 or any of the following: Mo9O26 or Mo8O23 or Mo17O47 or Mo4O11 or MoO2. One embodiment of the tungstenoxide may be cubic-tungsten oxide (H0.5WO3). Unexpectedly, it has been found that such metal oxide support modifiers can be combined with a precious metal or one or more active elements to create catalysts with multifunctionality. These catalysts could be used for the conversion of a carboxylic acid such as acetic, as well as its corresponding esters, e.g., Ethyl Acetate, to one or several hydrogenation products such as ethanol under hydrogenation conditions.
“Acidic support modifiers” can also be used in other embodiments. They include those from the group consisting ZrO2, Nb2O5, T2O5, Al2O3, and B2O3, as well as Sb2O3 and P2O5. The group that includes ZrO2, Al2O3, Ta2O5, and A2O3 is the acidic support modifiers.
“The modified support includes cobalt in addition to the support modifier. Modified support can contain from 0.5 to 20 wt. % cobalt (e.g. from 1 to 15 Wt. %, or between 1.5 and 10 wt. %. One embodiment of this is that the cobalt metal loading exceeds the one or more active metals.
“In some embodiments, the modified support may include a metal other than cobalt. The modified support should be substantially free from tin.
“In some embodiments, an acidic support modifier consists of a mixed metaloxide comprising at least one active metal and an oxide anion from a Group IVB or VB, VIB. VIII metal such as tungsten. For example, the oxide anion may take the form of tungstate, molybdate or vanadate. Examples of mixed metal oxides are cobalt-tungstate, cobalt molybdate and cobalt vanadate. One embodiment of the catalyst is free from tin-tungstate and substantially does not contain it. This has led to the discovery that catalysts with such mixed metal support modifiers can provide the desired degree in multifunctionality at higher conversions, e.g. increased ester conversion and reduced byproduct formation (e.g. reduced diethylether formation).
“In one embodiment, the catalyst contains 0.25 to 1.25 wt. % platinum and from 1-5 wt. Modified support: 1% tin. Modified support includes a silica support material or silica-alumina. A support modifier is used to place the cobalt on the support material. The weight of the support material can range from 5 to 15%. % acidic support modifiers such as V2O5 or MoO3. One embodiment may include cobalt-tungstate, e.g. in an amount of 0.1 to 20 wt. % or 5 to 15 wt. %.”
“Some embodiments include one or more active metals and one or more acidic modifiers. For example, the modified support could contain one or more active metals from copper, iron and vanadium as well as nickel, titanium, zinc and chromium. The support could include an active metal but not a precious metal and an acidic support modifier. The support modifier should consist of a support modifier metal from the group comprising tungsten, molybdenum vanadium and niobium. The final catalyst composition in this instance comprises a precious metal and one or more active elements disposed on the modified supports. Preferably, at least one active metal in the modified support is identical to at least one active metal disposed on the support. The catalyst could include a modified support with cobalt or tungsten (optionally WO3, H0.5WO3, and/or cobalt-tungstate). The catalyst may also include a precious metal such as palladium or platinum, and at most one active metal (e.g. cobalt and/or Tin) disposed on the modified supports.
“It is not known if the presence of tin-tungstate on the modified catalyst or support tends to decrease the catalytic activity of the conversion of Acetic Acid to Ethanol. Tin can contribute to increased catalytic activity, and a longer catalyst life when used with the modified support. The undesirable tin-tungstate species can form when tin is mixed with tungsten. Cobalt can be used to prevent the formation tin-tungstate. This allows cobalt to be formed preferentially over tin. This allows for the use of tin on modified supports to maintain adequate catalyst activity and lifetime. One embodiment of the modified support includes cobalt tungstate, tin, and the modified support is substantially devoid of tin.
“Processes to Making the Catalyst”
“The invention also addresses the manufacturing of the catalyst. The catalyst making process may enhance one or more of the following: acetic acid conversion; ester conversion; ethanol selectivity; overall productivity. One embodiment modifies the support with one or more support modifiers. The modified support is then impregnated with a precious and/or active metal to make the catalyst composition. The support can be immured with a support modifier solution that includes a support modifier precursor, and a cobalt pre-cursor. The modified support is then dried and calcined. Next, it is impregnated in a second solution that contains a precious metal precursor and optionally one of the active metal precursors. Finally, it is dried and calcined to make the final catalyst. It is preferred that the precious metal precursor, or any of the active metal precursors to the modified support are free from cobalt precursors.
“In this embodiment, the support modifier solution may include a cobalt precursor and a support modifier metal precursor. Preferably, the precursors are composed of salts of respective metals in solution that, when heated, can be converted to an elemental metallic form or a metal oxide. In this embodiment, the cobalt precursor is impregnated onto the support materials simultaneously and/or sequentially. This allows cobalt to interact with the support metal at a molecular level, which can lead to the formation of one or more polymetallic crystal species such as cobalt-tungstate. Other embodiments of cobalt do not interact with the precursor to the support modifier metal and are separately deposited onto the support material as either discrete metal nanoparticles (or an amorphous mixture). The support material can be modified with a cobalt pre-cursor while it is being modified with a support modifier. In this way, cobalt may interact with the support modifier to form one or more polymetallic crystal species.
“In some embodiments the support modifier can be added as particles to a support material. If desired, support modifier precursors may be mixed with the support material to add support. It is preferable for support modifiers to mix a powdered version of the support modifiers. The support modifier can be crushed, pelletized and sieved before being added to the support.
“As stated, in most embodiments the support modifier is preferably added via a wet impregnation step. A support modifier precursor to the support modifier is preferred. Alkali metaloxides, alkaline earth metallic oxides and/or Group IIB, IIIB, and IVB metals oxides are some examples of support modifier precursors.
“Although most metal oxides and polyoxoion sodiums are insoluble or have a limited solution chemistry, the isopoly- or heteropolyoxoanions from the early transition elements form an important exception. These complexes can be represented using the following formulae: Isopolyanions\n[XxMmOy]q? (x?m) Heteropolyanions\nwhere M is selected from tungsten, molybdenum, vanadium, niobium, tantalum and mixtures thereof, in their highest (d0, d1) oxidations states. Such polyoxometalate anions form a structurally distinct class of complexes based predominately, although not exclusively, upon quasi-octahedrally-coordinated metal atoms. Only elements with a favorable combination ionic radius, charge, and the ability to form D?-p? are able to function as addenda atoms in heteropoly- and isopolyanions. M-O bonds. The heteroatom, X is not restricted in any way. It can be chosen from almost any element, other than rare gases. See M. T. Pope (Heteropoly & Isopoly Oxometalates), Springer Verlag Berlin 1983, 180; Chap. 38, Comprehensive Coordination Chemistry, Vol. 3, 1028-58 Pergamon Press Oxford, 1987. The entireties are included herein by reference.”
The advantages of polyoxometalates, or POMs, and the heteropoly acids that they are derived from (HPAs), make them both economically and environmentally appealing. HPAs are strong in the Bronsted acidity superacid region. They are also efficient oxidants, exhibiting rapid reversible multielectron reactions under mild conditions. Solid HPAs have a distinct ionic structure that includes mobile basic structural units (H+, O+, H3O+ and H5O2+), as well as countercations (H+), heteropolyanions, and countercations. This is in contrast to zeolites or metal oxides.
“In light of the above, some embodiments of the support modifier precursor include a POM. Preferably, this metal is selected from the group consisting tungsten, molybdenum and niobium as well as vanadium, tantalum, vanadium, vanadium, and tantalum. Some embodiments include a hetero-POM. A non-limiting list of suitable POMs includes phosphotungstic acid (H?PW12) (H3PW12O40.nH2O), ammonium metatungstate (AMT) ((NH4)6H2W12O40.H2O), ammonium heptamolybdate tetrahydrate, (AHM) ((NH4)6Mo7O24.4H2O), silicotungstic acid hydrate (H?SiW12) (H4SiW12O40.H2O), silicomolybdic acid (H?SiMo12) (H4SiMo12O40.nH2O), and phosphomolybdic acid (H?PMo12) (H3PMo12O40.nH2O).”
“The unexpected and unexpectedly surprising discovery that POM-derived support modifiers can provide bi- or multiple-functional catalyst functionality in the catalyst compositions described in the invention has made them suitable for catalyzing mixed-feeds containing acetic and ethyl alcohol.
“Impregnation may occur simultaneously (coimpregnation), or sequentially. The two or more metal precursors are combined and then added to the support. Modified support is preferred. Drying and calcination completes the final catalyst composition. Simultaneous impregnation may require the use of a surfactant, dispersing agent or solubilizing agent (e.g. ammonium oxide or an acid like acetic or citric acid) to aid in dispersing and/or solubilizing the first, second, or optional third metal precursors.
In sequential impregnation the first metal precursor is added to the support, followed by drying and then calcining. The resulting material can then be impregnated using the second metal precursor, followed by another drying step, followed by a calcining step to create the final catalyst composition. You can add additional metal precursors, such as a third metal pre-cursor, to the support either in the first or second step of impregnation, and then dry and calcinate. If desired, you can use combinations of simultaneous and sequential impregnation.
“In embodiments in which the precious metal and/or one/more active metals (e.g. one or more of one, two, or three metals) are applied sequentially to the catalyst, i.e. in multiple impregnation step, the catalyst may be considered to have a plurality?theoretical layer? If cobalt is impregnated onto a support and then impregnated with an additional metal, the catalyst may have a first theoretical coating of cobalt and a second layer of the additional metal (e.g., Sn and/or Pt). In some cases, more than one active element precursor can be impregnated onto a support. This may allow for a theoretical layer to contain more than one metal, or even an oxide. It is preferable that the same metal precursor not be impregnated in multiple steps of sequential impregnation, resulting in the formation multiple theoretical layers containing the exact same metal or oxide. This is despite the use of the term “layers” in this context. It will be obvious to those who are skilled in the art that multiple layers can or may not form on the catalyst support depending on, for example, the conditions used in catalyst formation, the amount of metal used in each step, and the specific metals utilized.”
The modified supports can be shaped into the desired size distribution. For example, particles with an average particle size of 0.2 to 0.04 cm. You can extrude, pelletize, tabletize, press, crush, or sieve the supports to achieve the desired size distribution. You can use any of the many methods that are available to form the support materials into the desired size distribution. Support pellets can also be used as the base material for the modification support and final catalyst.
“In one embodiment, the catalyst according to the present invention can be prepared by bulk catalyst techniques. Bulk catalysts can be made by precipitating precursors to support modifiables and one or several active metals. Temperature, pressure, and/or pH can be adjusted to control precipitation. A binder may be used in some cases for bulk catalyst preparation. In bulk catalyst processes, a support material is not required. The bulk catalyst can be formed by spray drying, pelleting or granulating. You can use suitable bulk catalyst techniques such as those described by Krijn P. de Jong (ed. ), Synthesis of Solid Catalysts Wiley, 2009, pg. The entire content and disclosure are incorporated herein by reference.
“In one embodiment, the precious and/or active metals are impregnated onto the support. Preferably onto one of the above-described modified supports. Preferably, a precursor to the precious metal is used in the metal impregnation step. This could be a water-soluble compound or a complex that contains the precious metal of your choice. Precursors to active metals can also be imbedded into the support, but preferably modified support. It may be preferable to use a solvent such as water, glacial acid acetic acid or nitric acid depending on the metal precursors used. This will help dissolve one or more metal precursors.
“In one embodiment, different solutions of the metal precursors are formed. These are then subsequently mixed before being impregnated on the support. A first solution could consist of a first metal pre-cursor, while a second solution might include the second and third metal precursors. Preferably, at least one of the first, secondary, or optional third metal precursors is a precious metal, while the other(s), preferably active metal precursors, may or not contain precious metal precursors. Either one or both solutions should contain a solvent such as water or hydrochloric or glacial acetic acids.
“In one example embodiment, a solution including a first metal haloid is prepared. Optionally, the first metal halide may include a tin-containing halide. This could be a tin chloride like tin II chloride or tin IV chloride. A second metal precursor can be combined with the first solution as a solid, or separately, to create a combined solution. If used, the second metal precursor should be a second-metal oxalate or acetate, halide, or nitrate. Optionally, the first metal precursor may contain an active metal. This could be copper, iron or molybdenum as well as tungsten and tin. Another solution can also be prepared, which includes a precious metal halide. This is a halide that contains rhodium or ruthenium, palladium, or rhenium. The second solution can be combined with either the first or combined solution depending on whether the second metallic precursor is required to create a mixed metal precursor. The mixed metal precursor solution can then be added to the support. Modified support options are also available. Finally, dry and calcin the mixture to create the final catalyst composition. After the final calcination, the catalyst can be washed or not. Because some precursors are difficult to dissolve, it is possible to lower the pH of the first or second solution by using an acid like hydrochloric acid, acetic acid, or nitric acids, such as 6-10 M HNO3.
“Another aspect of the invention is that a first solution containing a first metal oxide is prepared. This could be an oxalate made from copper, iron or nickel. The first solution in this embodiment preferably contains an acid such as hydrochloric acid (PHC), phosphoric acid, or nitric acids, e.g. 6-10 M HNO3. A second metal precursor can be added to the first solution as either a solid or a separate solution. This will create a combined solution. If used, the second metal precursor preferably contains a second metal oxide, acetate or nitrate. It preferably also comprises an active metal. This includes copper, iron and molybdenum. Another solution can also be formed, which may include a precious metal oxide, such as an oxalate containing rhenium or ruthenium or platinum, or optionally an acid such acetic acid. The second solution can be combined with the first or combined solution depending on whether the second metallic precursor is desired. This creates a mixed metal pre-cursor solution. The mixed metal precursor solution can then be added to the support. Modified support options are also available. Finally, dry and calcin the mixture to create the final catalyst composition. After the final calcination, the catalyst can be washed.
“In one embodiment, ammonium oxide is used to facilitate the solubilization of at least one metal precursor, e.g. a tin precursor as described in U.S. Pat. No. No. 8,211,821, whose entirety is incorporated by reference. This aspect allows for the optional inclusion of an oxalate from a precious metal such as rhodium or palladium. A second metal precursor can optionally include an oxalate to tin. If desired, another active metal precursor may be a nitrate or halide or oxalate chromium or copper. This aspect allows for the addition of the first or second metal precursor to the solution. The third metal precursor can be added to the solution comprising the first and tin oxide precursors, or it may be mixed with the second metal precursor. To aid in the solubilization of the tin oxide, an acid like acetic acid or hydrochloric acid can be substituted. The mixed metal precursor solution can then be added to the support (or modified support) and dried. Finally, calcining the final catalyst composition may be done as described above.
The specific precursors used in different embodiments of the invention could vary. Metal halides, amine-soluble metal hydroxides and metal nitrates are all possible metal precursors. For example, suitable compounds for platinum precursors and palladium precursors include chloroplatinic acid, ammonium chloroplatinate, amine solubilized platinum hydroxide, platinum nitrate, platinum tetra ammonium nitrate, platinum chloride, platinum oxalate, palladium nitrate, palladium tetra ammonium nitrate, palladium chloride, palladium oxalate, sodium palladium chloride, sodium platinum chloride, and platinum ammonium nitrate, Pt(NH3)4(NO4)2. Aqueous solutions of soluble platinum compounds are preferred, both economically and environmentally. One embodiment of the precious metal precursor is not a metal-halide and is substantially uncontaminated with metal halides. In other embodiments, however, it is a precious metal halide.
“Use of Catalyst Hydrogenate Acetic Acid”
“The stability or activity of the catalyst for producing alcohol is one advantage of the catalysts of this invention. The catalysts of this invention can be used commercially in industrial applications for hydrogenation, especially in the production of alcohol. It is possible to attain a level of stability that the catalyst activity declines less than 6% every 100 hours, or less than 3% for 100 hours, respectively. The rate of productivity loss is best determined after the catalyst has reached steady-state conditions.
“In one embodiment, the invention is to a process of producing ethanol by hydrogenating feedstocks that contain compounds from acetic acid and ethyl-acetate or mixtures thereof. This can be done in the presence any of the described catalysts. One preferred reaction is to make alcohol from acetic acid. The hydrogenation reaction may be represented as follows:\nHOAc+2H2?EtOH+H2O\nIn some embodiments, the catalyst may be characterized as a bifunctional catalyst in that it effectively catalyzes the hydrogenation of acetic acid to ethanol as well as the conversion of ethyl acetate to one or more products, preferably ethanol.”
“The raw materials, hydrogen and acetic acid, that are fed to the reactor in connection with this invention, may be derived from any source, including natural gas and petroleum, coal, biomass and so on. Methanol carbonylation can be used to produce acetic acid. Other methods include acetaldehyde oxide, acetaldehyde reduction, ethane reduction, oxidative fermentation and anaerobic digestion. U.S. Pat. describes methanol carbonylation methods that can be used to produce acetic acid. Nos. Nos. The production of ethanol can be combined with such methanol-carbonylation processes.
“Petroleum and natural gas prices fluctuate making them more or less costly, so methods of producing acetic acids and intermediates such methanol from other carbon sources are gaining increasing attention. It may be advantageous to make acetic acid using synthesis gas (or?syngas) when petroleum is expensive. It is made from other carbon sources. U.S. Pat. No. No. 6,232,352, whose entirety is included herein by reference. It teaches how to retrofit a methanol plant for making acetic acid. Retrofitting an existing methanol plant can reduce or eliminate the high capital costs of CO generation for a new plant. To recover CO, all or part of the syngas can be diverted from the methanol synthesizer loop and sent to a separator unit. This is used to make acetic acid. Similar to the above, syngas may also be used to supply hydrogen for hydrogenation.
Syngas may partially or completely be used to produce some of the raw materials in some embodiments. Methanol and carbon monoxide can be used to form acetic acids, which can be made from syngas. Syngas can be made by steam reforming or partial oxidation reforming. The carbon monoxide can also be separated from the syngas. The hydrogen used to hydrogenate the acetic acids to make crude ethanol may also be separated from the syngas. Syngas can be obtained from a variety of carbon sources. For example, the carbon source could be chosen from natural gas, oil and petroleum, coal, or biomass. Bio-derived methane, which is produced from landfills and agricultural waste, can also be used to produce syngas or hydrogen.
Biomass-derived syngas is more stable than fossil fuels like coal and natural gas in terms of its 14C content. The Earth’s atmosphere is in an equilibrium between constant new formation, constant degradation. This means that the ratio of 14C nuclei to carbon in the atmosphere on Earth remains constant for long periods. Living organisms have the same distribution ratio of n14C to n12C as in the surrounding atmosphere. This equilibrium is reached at death, and 14C decays at half life of approximately 6000 years. The 14C content of methanol, acetic and/or ethanol derived from biomass-derived syngas should be substantially similar to that found in living organisms. The 14C to 12C ratios of methanol, Acetic acid, and/or Ethanol may range from about one-half to approximately 1 of the 14C to 12C ratio for living organisms. Other embodiments of the inventions describe syngas, Methanol, Acetic Acid, and/or Ethane derived entirely from fossil fuels. Carbon sources that were produced more than 60,000 years ago may not have any detectable 14C content.
“In another embodiment, the hydrogenation step can be performed using acetic acid obtained from fermentation of biomass. Preferably, the fermentation process uses an acetogenic or homoacetogenic microorganism that ferments sugars to acetic acids, with little to no carbon dioxide as a byproduct. Conventional yeast processing has a carbon efficiency of around 67%. The fermentation process’s carbon efficiency is preferably greater than 70%, 80%, or 90%. Optionally, the microorganism used in fermentation is selected from the following geni: Clostridium, Lactobacillus. Moorella. Propionibacterium. Propionispera. Anaerobiospirillum succinicproducens. Bacteroides amylophilus. Optionally, the entire or part of the unfermented biomass, e.g., the lignans may be gasified to make hydrogen which can be used in the hydrogenation stage of the invention. U.S. Pat. demonstrates several fermentation methods for the formation of acetic acid. No. No. Nos. Nos.
“Examples include but aren’t limited to agricultural wastes and forest products, as well as other cellulosic materials, timber harvesting residuals and softwood chips, hardwood chips, tree branches and stumps and leaves, bark and sawdust. Black liquor is another source of biomass. It is an aqueous solution containing lignin residues and hemicellulose as well as inorganic chemicals.
“U.S. Pat. No. No. 35,377 is also included herein by reference. It describes a method to produce methanol from carbonaceous materials like oil, coal and natural gas. This involves hydrogasification of solid or liquid carbonaceous materials in order to produce a process gas that is steam pyrolized and then enriched with natural gas to make syngas. The syngas can be converted to methanol, which may then be carbonylated into acetic acid. This method also produces hydrogen that can be used in conjunction with the invention, as previously mentioned. U.S. Pat. No. No. 5.821,111 discloses a method for converting waste biomass into syngas through gasification. No. No.
“The hydrogenation reactor can also be fed acetic acid and other carboxylic acids or anhydrides as well as aldehyde, acetaldehyde, and ketones such as acetone and acetaldehyde. The feedstock should consist of acetic acid, ethyl-acetate and preferred. One or more compounds from the group comprising acetic, acetic anhydride and acetaldehyde as well as acetaldehyde (acetaldehyde), acetaldehyde, acetaldehyde, acetaldehyde, acetaldehyde, ethyl alcohol, diethylether, and combinations thereof are suitable for acetic acids feed streams. In the process of the invention, these other compounds can also be hydrogenated. Propanol may be made more efficient by the presence of carboxylic acid, such as propanoic or its aldehyde in some embodiments. The acetic acid feed may also contain water.
“Alternatively, acetic acids in vapor may be taken directly from the flash vessel in a methanol-carbonylation unit according to U.S. Pat. No. No. 6,657,078, whose entirety is included herein by reference. For example, the crude vapor product may be fed directly into the hydrogenation reactor, without having to condense the acetic acid or light ends or remove water. This saves overall processing costs.
“In some embodiments of the reactor, a variety configurations may be used, including a fixed-bed reactor or a fluidized-bed reactor. An?adiabatic? reactor is possible in many embodiments. An?adiabatic? reactor can be used in many embodiments of the present invention. This means that there is no need for internal plumbing to pass heat through the reaction zone. Other embodiments use a radial flow or multiple reactors as the reactor. Alternatively, several reactors can be used with or without heat exchange, quenching or the introduction of additional feed material. A shell-and-tube reactor with heat transfer medium can also be used. The reaction zone can be contained in one vessel, or in multiple vessels that have heat exchangers.
“Preferential embodiments of the catalyst are used in a fixed-bed reactor, e.g. in the form of a tube or pipe, where reactants, usually in the vapor form and passed over or through it. You can also use fluid or ebullient-bed reactors. The hydrogenation catalysts can be combined with an inert substance to control the pressure drop through the catalyst bed as well as the time between the reactant compounds and the catalyst particles. Multiple catalyst beds may be used in one reactor, or in multiple reactors at once, depending on the embodiment. In one embodiment, the first catalyst acts in a first stage to hydrogenate a carboxylic acids, such as acetic, to their corresponding alcohols, e.g. ethanol. A second bifunctional catalyst is used in the second stage to convert unreacted acetic to ethanol and to convert byproduct esters, such as ethyl-acetate to additional products, most preferably to the ethanol. The invention’s catalysts can be used in any of these reaction systems, and in both the first or second stages.
“The hydrogenation is optionally performed at a pressure that is sufficient to overcome the pressure drop across catalytic beds at the GHSV chosen, but it is understood that significant pressure drop through reactor beds may be experienced at high spatial velocities, e.g. 5000 hr.1 or 6,500 hr.1.
“Even though the reaction requires two moles hydrogen per mole acetic to make one mole ethanol, the actual ratio of hydrogen and acetic in the feed stream can vary from 100:1 up to 1:100. For example, it could be 50:1 or 1:50, 20:1 or 1:2, 18:1 or 2:1. The molar ratio hydrogen to acetic acids should be greater than 2:1. This could mean that it is higher than 4:1 or 8:1. The molar ratio hydrogen to ethylacetate in a mixed feedstock may be higher than 5:1, e.g. greater than 10 or more than 15:1.
Contact or residence times can vary depending on factors such as the amount of feedstock (acetic and/or ethyl Acetate), catalyst, reactor temperature and pressure. Contact times can vary from a fraction to several hours if a catalyst system is not a fixed bed. For vapor phase reactions, preferred contact times are between 0.1 and 100 seconds.
“In particular, using the catalysts of this invention, hydrogenation of acetic and/or ethyl alcohol may result in favorable conversion, favorable selectivity, and productivity to ethanol within the reactor. The term “conversion” is used in the context of the present invention. The amount of acetic or ethyl alcohol in the feed is converted to another compound. The conversion percentage is based on the amount of acetic acid and ethyl alcohol in the feed. At least 20% of the acetic acid conversion can be achieved, but more preferable at least 60%, at minimum 75%, at most 80%, at best 90%, or at most 99%.
Ethyl acetate can be produced during the hydrogenation process of acetic acids. The conversion of ethylacetate to ethanol would be considered negative if you do not consume any ethylacetate from mixed vapor phase reactants. The monofunctional nature of some catalysts discussed herein makes them effective in converting acetic to ethanol but not ethyl. Monofunctional catalysts can lead to undesirable buildup of ethyl alcohol in the system, especially if the system uses one or more recycling streams that contain ethylacetate.
The preferred catalysts are multifunctional, meaning they can convert acetic acid into ethanol and also an alkyl alcetate (ethyl-acetate) to one or more other products. Multifunctional catalysts are preferably efficient for consuming ethylacetate at a sufficient rate to at least offset the rate at which ethyl-acetate is produced. This results in non-negative ethylacetate conversion. For example, ethyl-acetate conversions that are effectively 0% or greater than 0% may be achieved by using such catalysts. The invention’s catalysts can be effective in generating ethyl-acetate conversions of at minimum 0%, such as at least 5% or 10%, at most 15%, at most 20%, and at least 35%.
“In continuous processes, the amount of ethyl-acetate being added to the hydrogenation reactor (e.g., regenerated) and the amount of ethyl-acetate that leaves the reactor in the crude product should preferably approach a certain level once the process has reached equilibrium. Multifunctional catalysts that convert ethyl alcohol as well as acetic acids to ethyl are more efficient than monofunctional catalysts. Preferable embodiments have a concentration of less than 40 wt. %, less that 25 wt. %, less than 25 wt. After equilibrium is reached, %. Preferable embodiments form a crude product that is ethanol and ethyl-acetate. The crude product has an equilibrium concentration of ethylacetate ranging from 0.1 to 40 Wt. %, e.g. from 0.1 to 20% wt. %, or between 0.1 and 15 wt. %.”
“Catalysts with high acetic acid conversions (at least 60%) are desirable. However, some embodiments may have a lower conversion that is acceptable for high selectivity for alcohol. While it is easy to make up for lost conversion with appropriate recycle streams and larger reactors in most cases, it can be more difficult to compensate.
“Selectivity” is expressed as a percentage based on converted Acetic Acid and/or Ethyl Acetate. Each compound that is converted from acetic or ethyl alcohol has an independent selectivity. This selectivity is independent of the conversion. The ethanol selectivity is 60% if 60 mole percent of the converted Acetic Acid is converted to alcohol. The total selectivity of the invention is determined by the combination of converted acetic acid with ethyl alcohol. The preferred total selectivity to alcohol is at least 60%. This could be at least 70%, at minimum 80%, at most 85%, or at the very least 88%. The preferred hydrogenation processes also have low selectivity for undesirable products such as methane and ethane. Preferably, the selectivity to these unwanted products is lower than 4%. These undesirable products should not be detected in large quantities. The formation of alkanes can be very low. Ideally, it should not exceed 2%, 1% or 0.5% of the acetic acids passed over the catalyst. These alkanes are converted to fuel and have little other value.
“The term “productivity” is used herein. “Productivity” as it is used herein refers to the amount of product formed during hydrogenation. It is based on the number of kilograms of catalyst used each hour. Preferable productivity is at least 100g per kilogram of catalyst per hour. This means that at least 400g per hour of ethanol or 600 grams per kilogram per hour of catalyst are required. The productivity ranges from 100 to 3000 grams per kilogram of catalyst per hour. This could be as much as 400 to 2,500 grams per hour or 600 to 2,000g per kilogram per hour.
“In different embodiments of this invention, the crude alcohol product from the reactor will usually contain unreacted water, ethanol, and acetic acid before any subsequent processing such as purification or separation. Table 1 shows examples of compositional ranges for crude ethanol products. Table 1 lists the ‘others? The “others” listed in Table 1 could include, for instance, esters and ethers as well as aldehydes and ketones.
“TABLE 1nCRUDE ETHANOLPRODUCT COMPOSITIONSnConc. Conc. Conc. Conc.\nComponent (wt. %) (wt. %) (wt. %) (wt. %)nEthanol 5 – 72 15 – 72? 15 to 70 25-65?0? to 15?0? to 15?0? to 15?0? to 15?0? to 15?0? to15?0? to 15?0? to 15?0? to 15?0? to 15?0? to 15% nWater 5-40 10-30 10 to 26 nEthyl Acetate 1 to 30 0? to 25 0?3 to 20?5 to 18 nAcetaldehydehydehydehydehyde to 10 0? to 3 to 3 to 10 0? 0.1 to 3 0.2-2.0nOthers 0.1-10? 0.1 to 6? 0.1 to 6? ?”
“In one embodiment, crude ethanol products may contain acetic acid in a lower than 20 wt. %, e.g. of less than 15 Wt. %, less that 10 wt. %, less than 10 wt. %. The acetic acid concentration in Table 1 can range from 0.1 to 20 wt. % to 20 Wt. %, e.g., 0.1 wt. % to 15% wt. %, starting at 0.1 wt. % to 10 Wt. % to 10 wt. % up to 5 wt. %. If the embodiments contain lower amounts of Acetic Acid, the conversion of Acetic Acid is preferred to be greater than 75%. Additionally, the selectivity for ethanol may be high and greater than 75%.
“An ethanol product can be recovered from crude ethanol products produced by the reactor according to the invention. This may be done using several techniques.”
Summary for “Hydrogenation catalysts using cobalt-modified support”
The conventional production of ethanol for industrial use comes from petrochemical feedstocks such as oil, natural gases, and coal. It can also be made from feed stock intermediates such as syngas or starchy materials or cellulosic material such as corn or sugarcane. There are several conventional methods to produce ethanol from petrochemical feedstocks, including direct alcohol synthesis and methanol homologation. The volatility in petrochemical feed stocks prices causes fluctuations in conventionally produced ethanol’s cost. This makes it more difficult to find alternative sources of ethanol production when feed stock prices increase. Fermentation is used to convert starchy and cellulosic materials into ethanol. However, fermentation is used for the production of ethanol for human consumption or as fuel. The fermentation of cellulosic or starchy materials can also compete with food sources, limiting the amount of ethanol available for industrial use.
“Ethanol production by the reduction of alkanoic acid and/or other carbonyl-group-containing compounds has been extensively studied and many combinations of catalysts and supports have been described in the literature. EP0175558, and U.S. Patent. have proposed the reduction of various carboxylic acid over metal oxides. No. 4,398,039. Yokoyama, et.al., ‘Carboxylic acid and derivatives?, summarizes some of the development efforts in hydrogenation catalysts for various carboxylic acid conversions. Fine Chemicals Through HeterogeneousCatalysis 2001, 370-379.
“U.S. Pat. No. 8.080.694 is a description of a process to hydrogenate alkanoic acids. It involves passing a gaseous stream consisting hydrogen and an acid in the vapor stage over a hydrogenation catalyst comprising: A platinum group metal chosen from the group consisting mainly of palladium, platinum, rhenium, and combinations thereof; and a metallic promoter selected from the silicaceous supports consisting of WO3, MoO3, Fe2O3, and Cr2O3
“U.S. Pat. No. No. 6,495,730 describes a method for hydrogenating carboxylic acids using a catalyst consisting of activated carbon to support active metallic species such as ruthenium or tin. U.S. Pat. No. 6,204,417 describes another method for making aliphatic alcohols. This involves hydrogenating aliphatic carbonoxylic acids or anhydrides of esters thereof or lactones in presence of a catalyst consisting of Pt and Res. U.S. Pat. No. No. 5,149,680 describes a method for catalytic hydrogenation, which converts carboxylic acids to their anhydrides into alcohols and/or ester in the presence a catalyst containing a Group VIII metallic, such as palladium. This metal is capable of alloying with at least one of the Group VIII metals, rhenium, or tungsten. U.S. Pat. No. 4,777,303 describes a method for producing alcohols through the hydrogenation carboxylic acid in the presence a catalyst. The first component is either molybdenum/tungsten while the second component is a noble metal from Group VIII on high-surface area graphitized carbon. U.S. Pat. No. No. 4,804,791 describes another method for producing alcohols by hydrogenation of carboxylic acid in the presence a catalyst consisting of a noble metal from Group VIII or rhenium. U.S. Pat. No. No.
“The existing processes are not commercially viable because they lack the required selectivity for ethanol.
“A first embodiment of the invention relates to a catalyst that includes a precious metal and one (or more) active metals on a modified supporting. One embodiment of the modified support includes (i) support material, (ii), cobalt, and (iii), a support modifier that contains a metal from the group comprising vanadium, tungsten and tantalum. Modified support can contain from 0.5 to 20 wt. % cobalt, and a support modifier ranging from 0.1 to 40 Wt. Based on the total weight the catalyst, %. The modified support should not contain the precious metal or any of the active metals, especially tin.
“The precious metal is chosen from the group consisting rhenium (ruthenium), platinum, palladium and osmium as well as rhenium (rhenium), ruthenium), ruthenium (ruthenium), tin, nickel, zinc, manganese, cerium, iridium, and gold. One or more active elements are chosen from the group that includes copper, iron vanadium and nickel, as well as zinc, chromium and molybdenum. Preferably the precious metal is platinum, and the active metal is Tin. The amount of precious metal that may be present can range from 0.05 to 10 Wt. % and one or more active elements may be present in amounts between 0.1 and 20 wt. Based on the total weight, the percentage is %.
The support is preferred to be a silicaceous, e.g. silica, or carbon support (e.g. carbon black or activated charcoal), but any number of supports can be used. The support can be made from silica/alumina or titania, silica/alumina and calcium metasilicate. You can find tungsten in many forms as support modifiers, including tungsten oxide or tungstate of an active metal. The support modifier metal could include cobalt-tungstate, for example.
“Another embodiment of the invention is directed towards a synthesis process that comprises the following steps: (a) impregnating a support support material with a Cobalt precursor, support modifier precursor, to form first impregnated supports; (b) heating first impregnated supports to a first temperature in order to form modified support; (c), impregnating modified support with a secondary mixed precursor to form second impregnated supports; (d) heating second impregnated supports to a modified to create the catalyst, with at least one metal; provided that the precious and at least one metal are not cobalt.
“In a second embodiment the invention is directed at a catalyst consisting of a precious metal, at least one activate metal, and a modified support. The modified support comprises: (i) support material and (iii) cobalt-tungstate. One embodiment of the modified support also includes tungsten oxide. The modified support should be substantially free from tin. You can choose at least one of the following active metals: copper, iron vanadium or nickel, zinc, chromium and molybdenum; tungsten; tin; lanthanum, cerium or manganese.
“In a third embodiment of the invention, hydrogenation catalyst comprises a precious metal and support including cobalt. The catalyst has, after calcination a x-ray difffraction pattern substantially like that shown in Table 4. The hydrogenation catalyst should consist of a precious metal from the group consisting rhenium or ruthenium, palladium, platinum, osmium and iridium. It may also include at least one active element on a modified support. This means that the at least one active material is chosen from the following: copper, iron cobalt, vanadium and nickel; tungsten; tin; lanthanum and cerium; and zinc. A modified support could include a support material and cobalt-tungstate.
“Catalyst Composition”
The present invention relates to catalyst compositions which are suitable for hydrogenation catalysts and to processes for forming them, as well as chemical processes that employ such catalysts. Preferably, the catalysts comprise one or more active elements on a support. These catalysts may be useful in catalyzing hydrogenation of a carboxylic acids, e.g. acetic acid and/or its esters, such as ethyl alcohol.
“In one embodiment, an inventive catalyst consists of a precious metal and one to three active metals on a modified supporting. Preferably the precious metal and one of the active metals is not cobalt. Modified support includes a support material and a modifier that contains a metal from tungsten to vanadium to niobium. One aspect of the modified supports also includes cobalt. Modified support does not include any metals, such as any precious metal or one or more active, that have been added to the modified support. Copper, for example, is not added to modified support if it is an active metal. Cobalt, along with any precious metals and active metals, is not allowed to be deposited on modified supports. It is understood that cobalt is calcined onto the support material after the support modifier and cobalt are calcined.
It has been found that these catalysts can be used as multifunctional hydrogenation catalysts, capable of converting both carboxylic acid (e.g., Acetic Acid) and esters thereof to their corresponding alcohol(s), such as ethanol, under hydrogenation conditions. In another embodiment, the inventive catalyst includes a precious metal and an activate metal on a modified supporting. The catalyst is capable of converting acetic acids greater than 20%, greater that 75%, or greater then 90% and ethyl-acetate to ethanol more than 0%, 10%, or 20%.
“Precious Metals and Active Metals”
“The invention’s catalysts should contain at least one precious metal impregnated on the support. You can choose from rhodium or ruthenium, gold, platinum, palladium and osmium as the precious metal. The precious metal must be a metal other that cobalt for the purposes of the invention. The preferred precious metals to be used as catalysts in the invention are palladium and platinum. Preferably, the precious metal is active in hydrogenation of a carboxylic acids and/or its ester(s) to the corresponding alcohol(s). The precious metal can be either in its elemental or molecular form. These precious metals are not included in the catalyst. %, e.g. less than 3 Wt. %, less that 2 wt. %, less that 1 wt. %, less than 1 wt. %. The range of the precious metal that may be included in the catalyst is between 0.05 and 10 wt. %, e.g. From 0.1 to 5 Wt. % or from 0.1- 3 wt. Based on the total weight the catalyst, % In some cases, the precious metal’s metal loading may be lower than that of one or more active metals.
“In addition to the precious, the catalyst also includes one or more active elements disposed on the modified support. The present invention defines the one or more active elements as a metal other that cobalt. Cobalt, when it is part of the modified supports, may disperse any support modifier metal or oxide. When cobalt is added to the modified supports, it will be calcined on the support before the introduction or impregnation of the precious metal to that support.
“Active metals” can be used to refer to catalytically-active metals that increase the conversion, selectivity, and/or productivity. They may also include precious or nonprecious active elements. A catalyst that includes a precious metal and an activate metal can include (i) one or more precious metals and one or more non-precious metal active metals, (ii), two (or even more) precious metallics. As exemplary active metals, precious metals will be included in this document. It should also be noted that the term “active metal” is not intended to suggest that any particular metal is an active one. “Active metal” is used to describe some metals that are included in the invention’s catalysts. However, this does not imply that the precious metal in these catalysts is not catalytically activated.”
“In one embodiment, one or more active metals are included in the catalyst. They can be selected from the group consisting primarily of copper, iron vanadium and nickel, as well as tungsten and tin. One embodiment does not contain cobalt. One or more active metals are not to include precious metals. They include copper, iron vanadium and nickel, as well as zinc, chromium and molybdenum. The active metals can be selected from the group comprising copper, iron, zinc, chromium and tin. One embodiment may include tin mixed with at least one active metal. One or more active metals can be either in elemental or molecular form, e.g. an oxide of the active material, or a combination thereof.
“The weight of all active metals in the catalyst, including the precious metal mentioned, should be between 0.1 and 25 wt. %, e.g. from 0.5 to 15. wt. % or from 1.0-10 wt. %. One embodiment of the catalyst could contain cobalt in amounts ranging from 0.5 to 20 wt. %, and tin from 0.5 to 20wt. %. Modified support may be used to dispose of active metals. Weight percent, except where indicated otherwise, is calculated based on the total catalyst weight, including support.
“Some embodiments of the catalyst contain at least two active metals along with the precious metal. You can choose from any of these active metals, provided they are not identical to the precious metal. In some embodiments, additional active metals can also be used. In some embodiments, additional active metals may also be used on the support.
For some examples of bimetallic (precious/active metal+precious metal) combinations, these include platinum/ruthenium and platinum/ruthenium. Some embodiments of the catalyst include three metals on a support. For example, one precious metal and two metals. Exemplary tertiary combinations may include palladium/rhenium/tin, palladium/rhenium/nickel, platinum/tin/palladium, platinum/tin/rhodium, platinum/tin/gold, platinum/tin/iridium, platinum/tin/copper, platinum/tin/chromium, platinum/tin/zinc, platinum/tin/nickel, rhodium/nickel/tin, and rhodium/iron/tin. One preferred embodiment of the tertiary mixture at least contains tin. Some embodiments of the catalyst can contain more than three metals on a support.
“When the catalyst consists of a precious metal and one activate metal on a support the active metal is present at a level from 0.1 to 20 Wt. %, e.g. from 0.1-10 wt. % or from 0.1 up to 7.5 wt. %. If the catalyst contains two or more active elements in addition to the precious, such as a first and second active metals, the first metal can be present in the catalyst in amounts ranging from 0.05 to 20 Wt. %, e.g. From 0.1 to 10 wt. % or 0.5 to 5 Wt. %. The amount of the second active metal could be anywhere from 0.05 to 5 Wt. %, e.g. from 0.1 to 3.0 wt. % or 0.5 to 2.5 wt. %. One embodiment allows for a metal loading of less than 3 wt. when the second active element is tin. %, e.g. less than 2.5 wt. %, or less than 1.5 Wt. %. A catalyst with lower tin concentrations could have a longer lifetime, but this is not a limitation of theory. One embodiment of this invention states that the metal loading for the active metals is lower than the cobalt metal loading added to the modified support.
“In some embodiments, the catalyst may also contain a third active element. The third active metal can be present in amounts ranging from 0.05 to 20 Wt. %, e.g. from 0.05 to 7.5 wt. % or 0.05 to 7.5% wt. %. Active metals can be combined or separated.
“The preferred metal ratios can vary depending on the catalyst’s active metals. Some embodiments have a mole ratio between the precious metal and one or more active elements that ranges from 10:1-10:10. This could be, for example, from 1:1 to 1:4, 2:1 to 1:2, or 1.5:1-1:10. Another embodiment may contain the precious metal in a range of 0.1 to 5 weight. %, the first and second active metals in an amount of 0.5 to 20 Wt. %, the second active metal in an amounts of 0.5 to 20wt. Based on the catalyst’s total weight, %. Another embodiment of the precious metal contains a range from 0.1 to 5 Wt. %, the first and second active metals in an amount of 0.5 to 15 Wt. % and the second metal active in an amount of 0.5 to 15 Wt. %.”
“In another embodiment, cobalt can be added to the support material and then calcined as part the modified support. Tin is then subsequently added to this modified support. It is preferable to have a cobalt-tin ratio greater than 4:1. The multifunctionality of the catalyst may be enhanced by excess cobalt based on the molar ratio to tin.
“Support Materials”
“Catalysts according to the invention require a support material. Preferably, it should be modified. One embodiment may use an inorganic or organic oxide as the support material. One embodiment of the support material can be chosen from the following: silica/alumina; titania; silica/alumina; pyrogenic silica; high purity silica. zirconia. Carbon (e.g. carbon black or activated charcoal), zeolites, and combinations thereof. The support material should consist of silica, high purity silica or pyrogenic silica. One embodiment of the silicaceous supports material is free from alkaline earth metals such as calcium and magnesium. Preferable embodiments have the support material in a range of 25 to 99 wt. % to 99 Wt. %, e.g. from 30 wt. % to 98 Wt. % to 98 wt. % to 95 Wt. Based on the total weight the catalyst.
Preferable embodiments include a silicaceous supporting material, e.g. silica, with a surface area at least 50m2/g. The silicaceous support material should have a surface area of 50 to 600m2/g. This could be between 100 and 500 m2/g or 100 to 300m2/g. As used in the application, high surface area silica refers to silica with a minimum surface area of 250 m2/g. The present specification uses the term surface area to refer to BET nitrogen surface areas. This is the total surface area as per ASTM D6556-04. It is also incorporated by reference.
The preferred silicaceous support material should also have a pore size of 5 to 100nm, e.g. from 5-30 nm to 25 nm to 5-10 nm to 5-10 nm as determined using mercury intrusion porometry. It should also have a pore volume of 0.5 to 2.0 cm3/g. This corresponds to 0.7 to 1.5 cm3/g and 0.8 to1.3 cm3/g as determined via mercury intrusion perometry.
“The morphology and composition of the catalyst may differ widely. Some exemplary embodiments may use a variety of morphologies for the support material and/or the catalyst composition, including extrudates, spheres or spray dried microspheres. The silicaceous support material should have a morphology that permits for a packing density of 0.1 to 1.05 g/cm3, or 0.3 to 0.88 g/cm3. The silica support material should have an average particle size. This is the average size of spherical and non-spherical particles. It can range from 0.01 to 1.01 cm. The support generally contains very small metal (or metallic oxide) particles or crystallites. This should not have a significant impact on the size and shape of the catalyst particles. The above mentioned particle sizes are generally applicable to both the size and final catalyst particles. However, catalyst particles can be processed to make larger catalyst particles (e.g. extruded to create catalyst pellets).
“Support Modifiers”
A support modifier is a component of the support material. The support modifier can adjust the acidity of the supporting material. A support modifier may be any metal from the following group: tungsten, molybdenum vanadium, vanadium and niobium. An oxide of the metal may be used as a support modifier. The support modifiers may be present in a range of 0.1 to 50 wt. % to 50 Wt. %, e.g. from 0.2 wt. % to 25 Wt. %, starting at 0.5 wt. % to 20 Wt. % or 1 wt. % to 15% wt. Based on the total weight the catalyst. The support modifier can be present in amounts ranging from 0.1 to 40 weights if it contains vanadium, molybdenum and tungsten. %, e.g. from 0.1 to 30% wt. %, or between 0.1 and 20 wt. Based on the total weight, %
“In some embodiments, the support moderator may be an acidic modification that increases the acidity the catalyst. You can choose from the following group of acidic support modifiers: oxides in Group IVB, oxides in Group VB, oxides in Group VIB, oxides within Group VIIB, oxides within Group VIII, aluminum oxides and combinations thereof. One embodiment of the support modifier includes metal from the group consisting tungsten, molybdenum vanadium and niobium. Preferably, the support modifier is metal chosen from the group consisting tungsten, vanadium and tantalum. The support modifier should not contain phosphorous and not be made from a precursor containing phosphorous.
“In one embodiment, acidic modifiers may also include those from the group consisting WO3, MoO3, W49O119, W50O148 and W18O49. You can also use reduced tungsten oxides and molybdenum dioxides, such as W20O58 or W49O119 or W50O148 or W18O49 or any of the following: Mo9O26 or Mo8O23 or Mo17O47 or Mo4O11 or MoO2. One embodiment of the tungstenoxide may be cubic-tungsten oxide (H0.5WO3). Unexpectedly, it has been found that such metal oxide support modifiers can be combined with a precious metal or one or more active elements to create catalysts with multifunctionality. These catalysts could be used for the conversion of a carboxylic acid such as acetic, as well as its corresponding esters, e.g., Ethyl Acetate, to one or several hydrogenation products such as ethanol under hydrogenation conditions.
“Acidic support modifiers” can also be used in other embodiments. They include those from the group consisting ZrO2, Nb2O5, T2O5, Al2O3, and B2O3, as well as Sb2O3 and P2O5. The group that includes ZrO2, Al2O3, Ta2O5, and A2O3 is the acidic support modifiers.
“The modified support includes cobalt in addition to the support modifier. Modified support can contain from 0.5 to 20 wt. % cobalt (e.g. from 1 to 15 Wt. %, or between 1.5 and 10 wt. %. One embodiment of this is that the cobalt metal loading exceeds the one or more active metals.
“In some embodiments, the modified support may include a metal other than cobalt. The modified support should be substantially free from tin.
“In some embodiments, an acidic support modifier consists of a mixed metaloxide comprising at least one active metal and an oxide anion from a Group IVB or VB, VIB. VIII metal such as tungsten. For example, the oxide anion may take the form of tungstate, molybdate or vanadate. Examples of mixed metal oxides are cobalt-tungstate, cobalt molybdate and cobalt vanadate. One embodiment of the catalyst is free from tin-tungstate and substantially does not contain it. This has led to the discovery that catalysts with such mixed metal support modifiers can provide the desired degree in multifunctionality at higher conversions, e.g. increased ester conversion and reduced byproduct formation (e.g. reduced diethylether formation).
“In one embodiment, the catalyst contains 0.25 to 1.25 wt. % platinum and from 1-5 wt. Modified support: 1% tin. Modified support includes a silica support material or silica-alumina. A support modifier is used to place the cobalt on the support material. The weight of the support material can range from 5 to 15%. % acidic support modifiers such as V2O5 or MoO3. One embodiment may include cobalt-tungstate, e.g. in an amount of 0.1 to 20 wt. % or 5 to 15 wt. %.”
“Some embodiments include one or more active metals and one or more acidic modifiers. For example, the modified support could contain one or more active metals from copper, iron and vanadium as well as nickel, titanium, zinc and chromium. The support could include an active metal but not a precious metal and an acidic support modifier. The support modifier should consist of a support modifier metal from the group comprising tungsten, molybdenum vanadium and niobium. The final catalyst composition in this instance comprises a precious metal and one or more active elements disposed on the modified supports. Preferably, at least one active metal in the modified support is identical to at least one active metal disposed on the support. The catalyst could include a modified support with cobalt or tungsten (optionally WO3, H0.5WO3, and/or cobalt-tungstate). The catalyst may also include a precious metal such as palladium or platinum, and at most one active metal (e.g. cobalt and/or Tin) disposed on the modified supports.
“It is not known if the presence of tin-tungstate on the modified catalyst or support tends to decrease the catalytic activity of the conversion of Acetic Acid to Ethanol. Tin can contribute to increased catalytic activity, and a longer catalyst life when used with the modified support. The undesirable tin-tungstate species can form when tin is mixed with tungsten. Cobalt can be used to prevent the formation tin-tungstate. This allows cobalt to be formed preferentially over tin. This allows for the use of tin on modified supports to maintain adequate catalyst activity and lifetime. One embodiment of the modified support includes cobalt tungstate, tin, and the modified support is substantially devoid of tin.
“Processes to Making the Catalyst”
“The invention also addresses the manufacturing of the catalyst. The catalyst making process may enhance one or more of the following: acetic acid conversion; ester conversion; ethanol selectivity; overall productivity. One embodiment modifies the support with one or more support modifiers. The modified support is then impregnated with a precious and/or active metal to make the catalyst composition. The support can be immured with a support modifier solution that includes a support modifier precursor, and a cobalt pre-cursor. The modified support is then dried and calcined. Next, it is impregnated in a second solution that contains a precious metal precursor and optionally one of the active metal precursors. Finally, it is dried and calcined to make the final catalyst. It is preferred that the precious metal precursor, or any of the active metal precursors to the modified support are free from cobalt precursors.
“In this embodiment, the support modifier solution may include a cobalt precursor and a support modifier metal precursor. Preferably, the precursors are composed of salts of respective metals in solution that, when heated, can be converted to an elemental metallic form or a metal oxide. In this embodiment, the cobalt precursor is impregnated onto the support materials simultaneously and/or sequentially. This allows cobalt to interact with the support metal at a molecular level, which can lead to the formation of one or more polymetallic crystal species such as cobalt-tungstate. Other embodiments of cobalt do not interact with the precursor to the support modifier metal and are separately deposited onto the support material as either discrete metal nanoparticles (or an amorphous mixture). The support material can be modified with a cobalt pre-cursor while it is being modified with a support modifier. In this way, cobalt may interact with the support modifier to form one or more polymetallic crystal species.
“In some embodiments the support modifier can be added as particles to a support material. If desired, support modifier precursors may be mixed with the support material to add support. It is preferable for support modifiers to mix a powdered version of the support modifiers. The support modifier can be crushed, pelletized and sieved before being added to the support.
“As stated, in most embodiments the support modifier is preferably added via a wet impregnation step. A support modifier precursor to the support modifier is preferred. Alkali metaloxides, alkaline earth metallic oxides and/or Group IIB, IIIB, and IVB metals oxides are some examples of support modifier precursors.
“Although most metal oxides and polyoxoion sodiums are insoluble or have a limited solution chemistry, the isopoly- or heteropolyoxoanions from the early transition elements form an important exception. These complexes can be represented using the following formulae: Isopolyanions\n[XxMmOy]q? (x?m) Heteropolyanions\nwhere M is selected from tungsten, molybdenum, vanadium, niobium, tantalum and mixtures thereof, in their highest (d0, d1) oxidations states. Such polyoxometalate anions form a structurally distinct class of complexes based predominately, although not exclusively, upon quasi-octahedrally-coordinated metal atoms. Only elements with a favorable combination ionic radius, charge, and the ability to form D?-p? are able to function as addenda atoms in heteropoly- and isopolyanions. M-O bonds. The heteroatom, X is not restricted in any way. It can be chosen from almost any element, other than rare gases. See M. T. Pope (Heteropoly & Isopoly Oxometalates), Springer Verlag Berlin 1983, 180; Chap. 38, Comprehensive Coordination Chemistry, Vol. 3, 1028-58 Pergamon Press Oxford, 1987. The entireties are included herein by reference.”
The advantages of polyoxometalates, or POMs, and the heteropoly acids that they are derived from (HPAs), make them both economically and environmentally appealing. HPAs are strong in the Bronsted acidity superacid region. They are also efficient oxidants, exhibiting rapid reversible multielectron reactions under mild conditions. Solid HPAs have a distinct ionic structure that includes mobile basic structural units (H+, O+, H3O+ and H5O2+), as well as countercations (H+), heteropolyanions, and countercations. This is in contrast to zeolites or metal oxides.
“In light of the above, some embodiments of the support modifier precursor include a POM. Preferably, this metal is selected from the group consisting tungsten, molybdenum and niobium as well as vanadium, tantalum, vanadium, vanadium, and tantalum. Some embodiments include a hetero-POM. A non-limiting list of suitable POMs includes phosphotungstic acid (H?PW12) (H3PW12O40.nH2O), ammonium metatungstate (AMT) ((NH4)6H2W12O40.H2O), ammonium heptamolybdate tetrahydrate, (AHM) ((NH4)6Mo7O24.4H2O), silicotungstic acid hydrate (H?SiW12) (H4SiW12O40.H2O), silicomolybdic acid (H?SiMo12) (H4SiMo12O40.nH2O), and phosphomolybdic acid (H?PMo12) (H3PMo12O40.nH2O).”
“The unexpected and unexpectedly surprising discovery that POM-derived support modifiers can provide bi- or multiple-functional catalyst functionality in the catalyst compositions described in the invention has made them suitable for catalyzing mixed-feeds containing acetic and ethyl alcohol.
“Impregnation may occur simultaneously (coimpregnation), or sequentially. The two or more metal precursors are combined and then added to the support. Modified support is preferred. Drying and calcination completes the final catalyst composition. Simultaneous impregnation may require the use of a surfactant, dispersing agent or solubilizing agent (e.g. ammonium oxide or an acid like acetic or citric acid) to aid in dispersing and/or solubilizing the first, second, or optional third metal precursors.
In sequential impregnation the first metal precursor is added to the support, followed by drying and then calcining. The resulting material can then be impregnated using the second metal precursor, followed by another drying step, followed by a calcining step to create the final catalyst composition. You can add additional metal precursors, such as a third metal pre-cursor, to the support either in the first or second step of impregnation, and then dry and calcinate. If desired, you can use combinations of simultaneous and sequential impregnation.
“In embodiments in which the precious metal and/or one/more active metals (e.g. one or more of one, two, or three metals) are applied sequentially to the catalyst, i.e. in multiple impregnation step, the catalyst may be considered to have a plurality?theoretical layer? If cobalt is impregnated onto a support and then impregnated with an additional metal, the catalyst may have a first theoretical coating of cobalt and a second layer of the additional metal (e.g., Sn and/or Pt). In some cases, more than one active element precursor can be impregnated onto a support. This may allow for a theoretical layer to contain more than one metal, or even an oxide. It is preferable that the same metal precursor not be impregnated in multiple steps of sequential impregnation, resulting in the formation multiple theoretical layers containing the exact same metal or oxide. This is despite the use of the term “layers” in this context. It will be obvious to those who are skilled in the art that multiple layers can or may not form on the catalyst support depending on, for example, the conditions used in catalyst formation, the amount of metal used in each step, and the specific metals utilized.”
The modified supports can be shaped into the desired size distribution. For example, particles with an average particle size of 0.2 to 0.04 cm. You can extrude, pelletize, tabletize, press, crush, or sieve the supports to achieve the desired size distribution. You can use any of the many methods that are available to form the support materials into the desired size distribution. Support pellets can also be used as the base material for the modification support and final catalyst.
“In one embodiment, the catalyst according to the present invention can be prepared by bulk catalyst techniques. Bulk catalysts can be made by precipitating precursors to support modifiables and one or several active metals. Temperature, pressure, and/or pH can be adjusted to control precipitation. A binder may be used in some cases for bulk catalyst preparation. In bulk catalyst processes, a support material is not required. The bulk catalyst can be formed by spray drying, pelleting or granulating. You can use suitable bulk catalyst techniques such as those described by Krijn P. de Jong (ed. ), Synthesis of Solid Catalysts Wiley, 2009, pg. The entire content and disclosure are incorporated herein by reference.
“In one embodiment, the precious and/or active metals are impregnated onto the support. Preferably onto one of the above-described modified supports. Preferably, a precursor to the precious metal is used in the metal impregnation step. This could be a water-soluble compound or a complex that contains the precious metal of your choice. Precursors to active metals can also be imbedded into the support, but preferably modified support. It may be preferable to use a solvent such as water, glacial acid acetic acid or nitric acid depending on the metal precursors used. This will help dissolve one or more metal precursors.
“In one embodiment, different solutions of the metal precursors are formed. These are then subsequently mixed before being impregnated on the support. A first solution could consist of a first metal pre-cursor, while a second solution might include the second and third metal precursors. Preferably, at least one of the first, secondary, or optional third metal precursors is a precious metal, while the other(s), preferably active metal precursors, may or not contain precious metal precursors. Either one or both solutions should contain a solvent such as water or hydrochloric or glacial acetic acids.
“In one example embodiment, a solution including a first metal haloid is prepared. Optionally, the first metal halide may include a tin-containing halide. This could be a tin chloride like tin II chloride or tin IV chloride. A second metal precursor can be combined with the first solution as a solid, or separately, to create a combined solution. If used, the second metal precursor should be a second-metal oxalate or acetate, halide, or nitrate. Optionally, the first metal precursor may contain an active metal. This could be copper, iron or molybdenum as well as tungsten and tin. Another solution can also be prepared, which includes a precious metal halide. This is a halide that contains rhodium or ruthenium, palladium, or rhenium. The second solution can be combined with either the first or combined solution depending on whether the second metallic precursor is required to create a mixed metal precursor. The mixed metal precursor solution can then be added to the support. Modified support options are also available. Finally, dry and calcin the mixture to create the final catalyst composition. After the final calcination, the catalyst can be washed or not. Because some precursors are difficult to dissolve, it is possible to lower the pH of the first or second solution by using an acid like hydrochloric acid, acetic acid, or nitric acids, such as 6-10 M HNO3.
“Another aspect of the invention is that a first solution containing a first metal oxide is prepared. This could be an oxalate made from copper, iron or nickel. The first solution in this embodiment preferably contains an acid such as hydrochloric acid (PHC), phosphoric acid, or nitric acids, e.g. 6-10 M HNO3. A second metal precursor can be added to the first solution as either a solid or a separate solution. This will create a combined solution. If used, the second metal precursor preferably contains a second metal oxide, acetate or nitrate. It preferably also comprises an active metal. This includes copper, iron and molybdenum. Another solution can also be formed, which may include a precious metal oxide, such as an oxalate containing rhenium or ruthenium or platinum, or optionally an acid such acetic acid. The second solution can be combined with the first or combined solution depending on whether the second metallic precursor is desired. This creates a mixed metal pre-cursor solution. The mixed metal precursor solution can then be added to the support. Modified support options are also available. Finally, dry and calcin the mixture to create the final catalyst composition. After the final calcination, the catalyst can be washed.
“In one embodiment, ammonium oxide is used to facilitate the solubilization of at least one metal precursor, e.g. a tin precursor as described in U.S. Pat. No. No. 8,211,821, whose entirety is incorporated by reference. This aspect allows for the optional inclusion of an oxalate from a precious metal such as rhodium or palladium. A second metal precursor can optionally include an oxalate to tin. If desired, another active metal precursor may be a nitrate or halide or oxalate chromium or copper. This aspect allows for the addition of the first or second metal precursor to the solution. The third metal precursor can be added to the solution comprising the first and tin oxide precursors, or it may be mixed with the second metal precursor. To aid in the solubilization of the tin oxide, an acid like acetic acid or hydrochloric acid can be substituted. The mixed metal precursor solution can then be added to the support (or modified support) and dried. Finally, calcining the final catalyst composition may be done as described above.
The specific precursors used in different embodiments of the invention could vary. Metal halides, amine-soluble metal hydroxides and metal nitrates are all possible metal precursors. For example, suitable compounds for platinum precursors and palladium precursors include chloroplatinic acid, ammonium chloroplatinate, amine solubilized platinum hydroxide, platinum nitrate, platinum tetra ammonium nitrate, platinum chloride, platinum oxalate, palladium nitrate, palladium tetra ammonium nitrate, palladium chloride, palladium oxalate, sodium palladium chloride, sodium platinum chloride, and platinum ammonium nitrate, Pt(NH3)4(NO4)2. Aqueous solutions of soluble platinum compounds are preferred, both economically and environmentally. One embodiment of the precious metal precursor is not a metal-halide and is substantially uncontaminated with metal halides. In other embodiments, however, it is a precious metal halide.
“Use of Catalyst Hydrogenate Acetic Acid”
“The stability or activity of the catalyst for producing alcohol is one advantage of the catalysts of this invention. The catalysts of this invention can be used commercially in industrial applications for hydrogenation, especially in the production of alcohol. It is possible to attain a level of stability that the catalyst activity declines less than 6% every 100 hours, or less than 3% for 100 hours, respectively. The rate of productivity loss is best determined after the catalyst has reached steady-state conditions.
“In one embodiment, the invention is to a process of producing ethanol by hydrogenating feedstocks that contain compounds from acetic acid and ethyl-acetate or mixtures thereof. This can be done in the presence any of the described catalysts. One preferred reaction is to make alcohol from acetic acid. The hydrogenation reaction may be represented as follows:\nHOAc+2H2?EtOH+H2O\nIn some embodiments, the catalyst may be characterized as a bifunctional catalyst in that it effectively catalyzes the hydrogenation of acetic acid to ethanol as well as the conversion of ethyl acetate to one or more products, preferably ethanol.”
“The raw materials, hydrogen and acetic acid, that are fed to the reactor in connection with this invention, may be derived from any source, including natural gas and petroleum, coal, biomass and so on. Methanol carbonylation can be used to produce acetic acid. Other methods include acetaldehyde oxide, acetaldehyde reduction, ethane reduction, oxidative fermentation and anaerobic digestion. U.S. Pat. describes methanol carbonylation methods that can be used to produce acetic acid. Nos. Nos. The production of ethanol can be combined with such methanol-carbonylation processes.
“Petroleum and natural gas prices fluctuate making them more or less costly, so methods of producing acetic acids and intermediates such methanol from other carbon sources are gaining increasing attention. It may be advantageous to make acetic acid using synthesis gas (or?syngas) when petroleum is expensive. It is made from other carbon sources. U.S. Pat. No. No. 6,232,352, whose entirety is included herein by reference. It teaches how to retrofit a methanol plant for making acetic acid. Retrofitting an existing methanol plant can reduce or eliminate the high capital costs of CO generation for a new plant. To recover CO, all or part of the syngas can be diverted from the methanol synthesizer loop and sent to a separator unit. This is used to make acetic acid. Similar to the above, syngas may also be used to supply hydrogen for hydrogenation.
Syngas may partially or completely be used to produce some of the raw materials in some embodiments. Methanol and carbon monoxide can be used to form acetic acids, which can be made from syngas. Syngas can be made by steam reforming or partial oxidation reforming. The carbon monoxide can also be separated from the syngas. The hydrogen used to hydrogenate the acetic acids to make crude ethanol may also be separated from the syngas. Syngas can be obtained from a variety of carbon sources. For example, the carbon source could be chosen from natural gas, oil and petroleum, coal, or biomass. Bio-derived methane, which is produced from landfills and agricultural waste, can also be used to produce syngas or hydrogen.
Biomass-derived syngas is more stable than fossil fuels like coal and natural gas in terms of its 14C content. The Earth’s atmosphere is in an equilibrium between constant new formation, constant degradation. This means that the ratio of 14C nuclei to carbon in the atmosphere on Earth remains constant for long periods. Living organisms have the same distribution ratio of n14C to n12C as in the surrounding atmosphere. This equilibrium is reached at death, and 14C decays at half life of approximately 6000 years. The 14C content of methanol, acetic and/or ethanol derived from biomass-derived syngas should be substantially similar to that found in living organisms. The 14C to 12C ratios of methanol, Acetic acid, and/or Ethanol may range from about one-half to approximately 1 of the 14C to 12C ratio for living organisms. Other embodiments of the inventions describe syngas, Methanol, Acetic Acid, and/or Ethane derived entirely from fossil fuels. Carbon sources that were produced more than 60,000 years ago may not have any detectable 14C content.
“In another embodiment, the hydrogenation step can be performed using acetic acid obtained from fermentation of biomass. Preferably, the fermentation process uses an acetogenic or homoacetogenic microorganism that ferments sugars to acetic acids, with little to no carbon dioxide as a byproduct. Conventional yeast processing has a carbon efficiency of around 67%. The fermentation process’s carbon efficiency is preferably greater than 70%, 80%, or 90%. Optionally, the microorganism used in fermentation is selected from the following geni: Clostridium, Lactobacillus. Moorella. Propionibacterium. Propionispera. Anaerobiospirillum succinicproducens. Bacteroides amylophilus. Optionally, the entire or part of the unfermented biomass, e.g., the lignans may be gasified to make hydrogen which can be used in the hydrogenation stage of the invention. U.S. Pat. demonstrates several fermentation methods for the formation of acetic acid. No. No. Nos. Nos.
“Examples include but aren’t limited to agricultural wastes and forest products, as well as other cellulosic materials, timber harvesting residuals and softwood chips, hardwood chips, tree branches and stumps and leaves, bark and sawdust. Black liquor is another source of biomass. It is an aqueous solution containing lignin residues and hemicellulose as well as inorganic chemicals.
“U.S. Pat. No. No. 35,377 is also included herein by reference. It describes a method to produce methanol from carbonaceous materials like oil, coal and natural gas. This involves hydrogasification of solid or liquid carbonaceous materials in order to produce a process gas that is steam pyrolized and then enriched with natural gas to make syngas. The syngas can be converted to methanol, which may then be carbonylated into acetic acid. This method also produces hydrogen that can be used in conjunction with the invention, as previously mentioned. U.S. Pat. No. No. 5.821,111 discloses a method for converting waste biomass into syngas through gasification. No. No.
“The hydrogenation reactor can also be fed acetic acid and other carboxylic acids or anhydrides as well as aldehyde, acetaldehyde, and ketones such as acetone and acetaldehyde. The feedstock should consist of acetic acid, ethyl-acetate and preferred. One or more compounds from the group comprising acetic, acetic anhydride and acetaldehyde as well as acetaldehyde (acetaldehyde), acetaldehyde, acetaldehyde, acetaldehyde, acetaldehyde, ethyl alcohol, diethylether, and combinations thereof are suitable for acetic acids feed streams. In the process of the invention, these other compounds can also be hydrogenated. Propanol may be made more efficient by the presence of carboxylic acid, such as propanoic or its aldehyde in some embodiments. The acetic acid feed may also contain water.
“Alternatively, acetic acids in vapor may be taken directly from the flash vessel in a methanol-carbonylation unit according to U.S. Pat. No. No. 6,657,078, whose entirety is included herein by reference. For example, the crude vapor product may be fed directly into the hydrogenation reactor, without having to condense the acetic acid or light ends or remove water. This saves overall processing costs.
“In some embodiments of the reactor, a variety configurations may be used, including a fixed-bed reactor or a fluidized-bed reactor. An?adiabatic? reactor is possible in many embodiments. An?adiabatic? reactor can be used in many embodiments of the present invention. This means that there is no need for internal plumbing to pass heat through the reaction zone. Other embodiments use a radial flow or multiple reactors as the reactor. Alternatively, several reactors can be used with or without heat exchange, quenching or the introduction of additional feed material. A shell-and-tube reactor with heat transfer medium can also be used. The reaction zone can be contained in one vessel, or in multiple vessels that have heat exchangers.
“Preferential embodiments of the catalyst are used in a fixed-bed reactor, e.g. in the form of a tube or pipe, where reactants, usually in the vapor form and passed over or through it. You can also use fluid or ebullient-bed reactors. The hydrogenation catalysts can be combined with an inert substance to control the pressure drop through the catalyst bed as well as the time between the reactant compounds and the catalyst particles. Multiple catalyst beds may be used in one reactor, or in multiple reactors at once, depending on the embodiment. In one embodiment, the first catalyst acts in a first stage to hydrogenate a carboxylic acids, such as acetic, to their corresponding alcohols, e.g. ethanol. A second bifunctional catalyst is used in the second stage to convert unreacted acetic to ethanol and to convert byproduct esters, such as ethyl-acetate to additional products, most preferably to the ethanol. The invention’s catalysts can be used in any of these reaction systems, and in both the first or second stages.
“The hydrogenation is optionally performed at a pressure that is sufficient to overcome the pressure drop across catalytic beds at the GHSV chosen, but it is understood that significant pressure drop through reactor beds may be experienced at high spatial velocities, e.g. 5000 hr.1 or 6,500 hr.1.
“Even though the reaction requires two moles hydrogen per mole acetic to make one mole ethanol, the actual ratio of hydrogen and acetic in the feed stream can vary from 100:1 up to 1:100. For example, it could be 50:1 or 1:50, 20:1 or 1:2, 18:1 or 2:1. The molar ratio hydrogen to acetic acids should be greater than 2:1. This could mean that it is higher than 4:1 or 8:1. The molar ratio hydrogen to ethylacetate in a mixed feedstock may be higher than 5:1, e.g. greater than 10 or more than 15:1.
Contact or residence times can vary depending on factors such as the amount of feedstock (acetic and/or ethyl Acetate), catalyst, reactor temperature and pressure. Contact times can vary from a fraction to several hours if a catalyst system is not a fixed bed. For vapor phase reactions, preferred contact times are between 0.1 and 100 seconds.
“In particular, using the catalysts of this invention, hydrogenation of acetic and/or ethyl alcohol may result in favorable conversion, favorable selectivity, and productivity to ethanol within the reactor. The term “conversion” is used in the context of the present invention. The amount of acetic or ethyl alcohol in the feed is converted to another compound. The conversion percentage is based on the amount of acetic acid and ethyl alcohol in the feed. At least 20% of the acetic acid conversion can be achieved, but more preferable at least 60%, at minimum 75%, at most 80%, at best 90%, or at most 99%.
Ethyl acetate can be produced during the hydrogenation process of acetic acids. The conversion of ethylacetate to ethanol would be considered negative if you do not consume any ethylacetate from mixed vapor phase reactants. The monofunctional nature of some catalysts discussed herein makes them effective in converting acetic to ethanol but not ethyl. Monofunctional catalysts can lead to undesirable buildup of ethyl alcohol in the system, especially if the system uses one or more recycling streams that contain ethylacetate.
The preferred catalysts are multifunctional, meaning they can convert acetic acid into ethanol and also an alkyl alcetate (ethyl-acetate) to one or more other products. Multifunctional catalysts are preferably efficient for consuming ethylacetate at a sufficient rate to at least offset the rate at which ethyl-acetate is produced. This results in non-negative ethylacetate conversion. For example, ethyl-acetate conversions that are effectively 0% or greater than 0% may be achieved by using such catalysts. The invention’s catalysts can be effective in generating ethyl-acetate conversions of at minimum 0%, such as at least 5% or 10%, at most 15%, at most 20%, and at least 35%.
“In continuous processes, the amount of ethyl-acetate being added to the hydrogenation reactor (e.g., regenerated) and the amount of ethyl-acetate that leaves the reactor in the crude product should preferably approach a certain level once the process has reached equilibrium. Multifunctional catalysts that convert ethyl alcohol as well as acetic acids to ethyl are more efficient than monofunctional catalysts. Preferable embodiments have a concentration of less than 40 wt. %, less that 25 wt. %, less than 25 wt. After equilibrium is reached, %. Preferable embodiments form a crude product that is ethanol and ethyl-acetate. The crude product has an equilibrium concentration of ethylacetate ranging from 0.1 to 40 Wt. %, e.g. from 0.1 to 20% wt. %, or between 0.1 and 15 wt. %.”
“Catalysts with high acetic acid conversions (at least 60%) are desirable. However, some embodiments may have a lower conversion that is acceptable for high selectivity for alcohol. While it is easy to make up for lost conversion with appropriate recycle streams and larger reactors in most cases, it can be more difficult to compensate.
“Selectivity” is expressed as a percentage based on converted Acetic Acid and/or Ethyl Acetate. Each compound that is converted from acetic or ethyl alcohol has an independent selectivity. This selectivity is independent of the conversion. The ethanol selectivity is 60% if 60 mole percent of the converted Acetic Acid is converted to alcohol. The total selectivity of the invention is determined by the combination of converted acetic acid with ethyl alcohol. The preferred total selectivity to alcohol is at least 60%. This could be at least 70%, at minimum 80%, at most 85%, or at the very least 88%. The preferred hydrogenation processes also have low selectivity for undesirable products such as methane and ethane. Preferably, the selectivity to these unwanted products is lower than 4%. These undesirable products should not be detected in large quantities. The formation of alkanes can be very low. Ideally, it should not exceed 2%, 1% or 0.5% of the acetic acids passed over the catalyst. These alkanes are converted to fuel and have little other value.
“The term “productivity” is used herein. “Productivity” as it is used herein refers to the amount of product formed during hydrogenation. It is based on the number of kilograms of catalyst used each hour. Preferable productivity is at least 100g per kilogram of catalyst per hour. This means that at least 400g per hour of ethanol or 600 grams per kilogram per hour of catalyst are required. The productivity ranges from 100 to 3000 grams per kilogram of catalyst per hour. This could be as much as 400 to 2,500 grams per hour or 600 to 2,000g per kilogram per hour.
“In different embodiments of this invention, the crude alcohol product from the reactor will usually contain unreacted water, ethanol, and acetic acid before any subsequent processing such as purification or separation. Table 1 shows examples of compositional ranges for crude ethanol products. Table 1 lists the ‘others? The “others” listed in Table 1 could include, for instance, esters and ethers as well as aldehydes and ketones.
“TABLE 1nCRUDE ETHANOLPRODUCT COMPOSITIONSnConc. Conc. Conc. Conc.\nComponent (wt. %) (wt. %) (wt. %) (wt. %)nEthanol 5 – 72 15 – 72? 15 to 70 25-65?0? to 15?0? to 15?0? to 15?0? to 15?0? to 15?0? to15?0? to 15?0? to 15?0? to 15?0? to 15?0? to 15% nWater 5-40 10-30 10 to 26 nEthyl Acetate 1 to 30 0? to 25 0?3 to 20?5 to 18 nAcetaldehydehydehydehydehyde to 10 0? to 3 to 3 to 10 0? 0.1 to 3 0.2-2.0nOthers 0.1-10? 0.1 to 6? 0.1 to 6? ?”
“In one embodiment, crude ethanol products may contain acetic acid in a lower than 20 wt. %, e.g. of less than 15 Wt. %, less that 10 wt. %, less than 10 wt. %. The acetic acid concentration in Table 1 can range from 0.1 to 20 wt. % to 20 Wt. %, e.g., 0.1 wt. % to 15% wt. %, starting at 0.1 wt. % to 10 Wt. % to 10 wt. % up to 5 wt. %. If the embodiments contain lower amounts of Acetic Acid, the conversion of Acetic Acid is preferred to be greater than 75%. Additionally, the selectivity for ethanol may be high and greater than 75%.
“An ethanol product can be recovered from crude ethanol products produced by the reactor according to the invention. This may be done using several techniques.”
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