Chemical Products – Xiaohao Liu, Yuebing Xu, Feng Jiang, Bing Liu, Dapeng Liu, Ting Wang, Jiangnan University
Abstract for “Multistage nanoreactor catalyst preparation and application”
The present disclosure discloses a multistage catalyst for synthesis gas conversion, as well as its preparation and application. The core of the Fischer-Tropsch iron-based catalyst is surrounded by a transition layer of porous oxide or porous carb material and a shell layer that has an aromatization function. A metal element or non-metal element can modify the molecular Sieve’s shell layer. The outer surface of the molecular Sieve can also be modified with a silicon-oxygen compound. This adjusts the acidic site and aperture to prevent the formation heavy aromatic hydrocarbons. The disclosure states that the iron-based Fischer?Tropsch catalyst can prepare the shell layer molecular Sieve with a transition and a shell layer containing, or not containing, auxiliaries. It can also be prepared with or without surface modification. The catalyst is suitable for the direct preparation of aromatic compounds from synthesis gas, particularly light aromatic compounds. It has a selectivity of 75% or higher in light aromatic hydrocarbons, and a minimum of 95% in liquid phase products. The catalyst also has excellent stability and industrial potential.
Background for “Multistage nanoreactor catalyst preparation and application”
“Aromatic chemicals, including benzene (BTX), are important chemical base raw materials. They are mainly derived from petroleum based production processes such as naphtha steam-crackering to produce ethylene, and catalytic reforming or cracking to make gasoline and diesel. The increasing environmental issues and light weight of olefins has made it difficult and impossible to acquire aromatic compounds from petroleum. The non-petroleum route for preparing aromatic hydrocarbons is receiving more attention.
China, based on its energy structure of rich coal, poor petroleum and coal, has supported the development of new technologies to produce various chemical products using coal or biomass as raw materials over the past decade. This was done from the perspective both of energy safety and energy strategy, in order to decrease the dependency on petroleum. The direct preparation of aromatic hydrocarbons using synthesis gas is a viable technical option for producing BTX. This is important for utilizing China?s rich coal resources as well as reducing dependence on petroleum. This process doesn’t require additional preparation of aromatic hydrocarbons synthesis gas through dimethyl ether or methanol as in an indirect process. The process is simplified and costs are lower, which makes it a much more attractive investment.
Direct composite catalysts do not allow for the preparation of aromatic hydrocarbons directly from synthesis gases. To activate and react, intermediates susceptible to aromatization (C2?C5) must still undergo diffusion. These intermediates also have the possibility to escape. After CO is converted to CO, it often becomes inactive and cannot react with a second catalyst. The physical mixing can easily cause non-uniform distributions of active site concentrations in a reaction system. This will impact the aromatization reaction to the intermediates to varying degrees. These problems can lead to low selectivity and yield for aromatic hydrocarbons, particularly light aromatic hydrocarbons like benzene, xylene, and toluene.
“Considering the shortcomings in conventional catalysts, this disclosure is about a multistage, nanoreactor catalyst that can be used to prepare aromatic compounds from synthetic gas in one step. It also allows for preparation and application of these compounds in reactions of preparing aromatic compounds from synth gas. This catalyst is highly aromatic hydrocarbon selective, particularly for light aromatic hydrocarbons. It will be used industrially.
“The multistage nanoreactor catalytic catalyst of the present disclosure is for directly preparing aromatic compounds out of synthesis gas. It consists of a core structure, a shell body, and a core/shell transition layer (as illustrated in FIG. 1). The core layer, an iron-based catalyst with Fischer-Tropsch activation for activating CO, H2 and CO2, and forming a main product from olefin. The shell body is a molecular sieve to form an aromatic hydrocarbon product. Its weight is 0.1% to 80 % of total catalyst weight. The core-shell transition layers are a porous oxide and porous carbon material. Their weight is 0.1% to 35%.
“In one embodiment, the iron-based catalytic with Fischer-Tropsch activity can be supported or unsupported, and may contain or not contain aniliaries.”
“In one embodiment, the molecular Sieve is one or more of ZSM-5 or MCM-22, MCM-50, MCM-49, or SAPO-34 zeolite molecularsieve materials.”
“In one embodiment, the molecular Sieve may contain or not auxiliaries.”
“In one embodiment, the outer surface molecular sieve may have or not a silicon-oxygen compound.”
“In one embodiment, the silica/alumina ratio of zeolite molecular Sieve is preferably between 10 and 500. When auxiliaries have been added, they are P, V. Cr. Mn. Fe. Co. Cu. Zn. Ga. Ge. Mo. Ru. Pd. Ag. W. The weight of auxiliaries is 0.01% – 35% of shell layer weight based on atoms. And the weight silicon-oxygen compound is 0.01% -oxygen layer is from 20% to 20% of the shell layers.
“In one embodiment, the transition layer of the present disclosure is porous. It can be one or more of aluminum oxide (silicon oxide), zirconium oxide (zirconium oxide), magnesium oxide, zinc oxides, titanium oxide, calcium oxide, and zinc oxide. The thickness of the transition layers is 0.1 to 1000nm, preferable 0.5 to 100nm.
“A preparation process for the catalyst according the present disclosure includes the following steps:
“Step 3, mix the powder from step 2 into a solution containing the soluble metal salt by an incipient dryness impregnation or an ion exchanging method or an excess impregnation. The soluble salt should be preferably one or more of the following: nitrate; carbonate; acetate; tungstate or chloride.
“In one embodiment, the present disclosure, step 1 the organic solvent is one of ethanol or propanol.
“In one embodiment of the present disclosure, in step 2, the adopted template is one or more of tetrapropylammonium hydroxide, n-propylamine, isopropylamine, hexamethyleneimine, triethylamine and tetraethylammonium hydroxide; the silicon source is one or more of silicon oxide, sodium silicate, propyl orthosilicate, hexamethyldisiloxane, ethyl orthosilicate and isopropyl orthosilicate; the aluminum source is one or more of alumina, aluminum isopropoxide trihydrate, sodium aluminate, aluminum sulfate, boehmite and gibbsite; and the alkali is one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate and sodium acetate.”
“The present disclosure also reveals a method to apply the catalyst to directly prepare aromatic compounds from synthetic gas.”
“The reaction using catalysts of the present disclosure may be performed in a fluidized or fixed bed reactor. Preferably, a fluidized or fixed bed reactor.”
“The present disclosure offers the following benefits:
“(1) The multistage nanoreactor catalyst in the present disclosure can effectively eliminate the influence of the shell-based molecular sieve upon the core catalyst, increase the conversion rate CO and promote further conversion. The present disclosure provides a catalyst that can be used to prepare aromatic hydrocarbons directly using natural gas-based synthesis gases, including coal-based, biomass, and natural gas-based raw materials. It is particularly suitable for the preparation of light aromatic compounds.
“(2) The multistage catalyst for nanoreactors prepared in this disclosure has a relatively high aromatic hydrocarbon selectivity. It can be more effective at inhibiting heavy and polycyclic aromatic hydrocarbons such as naphthalene and has comparatively low methane selectivity.”
“(3) The catalyst is stable and has good industrial applications prospects.”
“BRIEF DESCRIPTION ABOUT FIGURES”
“FIG. “FIG.
“Examples 1 to 6: Preparation Multistage Nanoreactor Catalyst For Direct Conversion Of Synthesis Gas To Aromatic Compounds”
“Product analysis: The products from the reactor were condensed into a cold trap and the uncondensed parts were analysed on-line using a gaschromatography with TCD/FID detectors. The unreacted CO, formed CH4 and CO2, and the inert gas N2 were separated using a packed column of TDX-01. TCD detected the N2 and used it as an internal standard substance to calculate CO conversion. Separation of C1-C5 hydrocarbons was done using an HP-PLOT/Al2O3 Capillary Column. After reaction, the condensed hydrocarbons were collected and analysed by an additional gas chromatography off line which connected with an FID as well as a HP-1 or HPAP capillary column for further separation of meta-, para- and ortho-xylene.
“where (ACO/AN2 )in and(ACO/AN2 )out are respectively the peak areas ratios of CO and N2 at the outlet and inlet of the reactor.”
“where (ACO2 /AN 2 2)out is the peak area ratio CO2 to nitrogen2. fCO 2 & fCO 2 are the correction factors for CO2 and CO2, respectively.
“(3) The selectivity for CO to be converted to hydrocarbons (SCO-HC) was calculated to: nSCOto HC=100?SCO2”
“Certainly, the CO2-free selectivities for CO converted to CH4, and C2-C6 in the gas phase, respectively, as well as hydrocarbons in the liquid phase, namely, the CO2-free distribution of hydrocarbons, were calculated as follows:
“Where SCO is CH 4, is the selectivity for CH4. (ACH 4/AN 2 )out represents the online TCD peak area CH4 ratio from CH4 to N2. fCH 4 represents the correction factor for CH4.
“Where ACn FID1 is the peak area of on-line Cn(n=2-6) or CH4, respectively; and fCn FID1 is the correction factor of Cn (n=2-6) or CH4 in online FID.
“a”) The CO2-free selectivities for CO converted into total hydrocarbons in liquid phases were calculated as:nSCOto C liquid phase =100?SCOto CH4? ?n=2 6SCO and C n
“Where ACn FID2 represents the off-line peak area for Cn(n>=5), fCn FID2 refers to the correction factors for Cn(n>=5)4 off-line.
“Example 1”
“Example 2”
“Example 3”
“Take 5g of 20 Wt % Fe1 and 20 Wt % SiO2 supported iron-based catalyst prepared by an incipient wetness impregnation process. Mix the sample in 50 mL aluminum isopropoxide trihydrate. Stir continuously. Dry the mixture and then calcine the iron catalyst sample with an Al2O3 coating.
“Example 4”
“Example 5”
“Example 6”
“Examples 7:11: Use of Invented Catalysts to Convert Synthesis Gas To Aromatic Hydrocarbons
Make the catalyst at 6.5 MPa pressure. Then crush the material and sieve it to get a sample of 40-60 meshes. You should add 1.0 g catalyst to a continuous flow reactor. The catalyst was pre-reduced using one or more hydrogen, carbon monoxides, methane, ethane, or ethylene gases for a period of time. After that, the reactor was cooled to the temperature necessary for continuous reaction. For calculating the CO conversion rate, the reaction gas contained 45 vol% CO, 45vol% H2 and four vol% N2. The internal standard gas was N2. A gas chromatograph with a thermal conductivity detector and a hydrogen-ion flame detector was used to analyze the product under atmospheric pressure. The cold trap product was then analyzed off-line by another gaschromatograph with a hydrogen flame detector.
“Example 7”
“Example 8”
“Example 9”
“Example 10”
“Example 11”
“Comparative Example 1”.
“Comparative example 2”
It is evident from the comparison of these examples with the comparative examples in Tables 1, 2 that the catalyst containing transition layer oxide and having the molecular sieve layers being modified internally or externally has a higher selectivity for light aromatic hydrocarbons. The highest BTX selectivity of 76.9% is 76.9%. In particular, the selectivity towards xylene reaches 30% and above. This accounts for between 80 and 90% of the xylene. The catalysts without the molecular sieve layer being modified internally or externally produce more heavy aromatic hydrocarbon products.
“The scope of the disclosure described and claimed in this document is not limited by the particular aspects disclosed. Anyone skilled in the arts can modify the disclosure without affecting its spirit or scope. “The claims should define the scope of protection for the disclosure.
Summary for “Multistage nanoreactor catalyst preparation and application”
“Aromatic chemicals, including benzene (BTX), are important chemical base raw materials. They are mainly derived from petroleum based production processes such as naphtha steam-crackering to produce ethylene, and catalytic reforming or cracking to make gasoline and diesel. The increasing environmental issues and light weight of olefins has made it difficult and impossible to acquire aromatic compounds from petroleum. The non-petroleum route for preparing aromatic hydrocarbons is receiving more attention.
China, based on its energy structure of rich coal, poor petroleum and coal, has supported the development of new technologies to produce various chemical products using coal or biomass as raw materials over the past decade. This was done from the perspective both of energy safety and energy strategy, in order to decrease the dependency on petroleum. The direct preparation of aromatic hydrocarbons using synthesis gas is a viable technical option for producing BTX. This is important for utilizing China?s rich coal resources as well as reducing dependence on petroleum. This process doesn’t require additional preparation of aromatic hydrocarbons synthesis gas through dimethyl ether or methanol as in an indirect process. The process is simplified and costs are lower, which makes it a much more attractive investment.
Direct composite catalysts do not allow for the preparation of aromatic hydrocarbons directly from synthesis gases. To activate and react, intermediates susceptible to aromatization (C2?C5) must still undergo diffusion. These intermediates also have the possibility to escape. After CO is converted to CO, it often becomes inactive and cannot react with a second catalyst. The physical mixing can easily cause non-uniform distributions of active site concentrations in a reaction system. This will impact the aromatization reaction to the intermediates to varying degrees. These problems can lead to low selectivity and yield for aromatic hydrocarbons, particularly light aromatic hydrocarbons like benzene, xylene, and toluene.
“Considering the shortcomings in conventional catalysts, this disclosure is about a multistage, nanoreactor catalyst that can be used to prepare aromatic compounds from synthetic gas in one step. It also allows for preparation and application of these compounds in reactions of preparing aromatic compounds from synth gas. This catalyst is highly aromatic hydrocarbon selective, particularly for light aromatic hydrocarbons. It will be used industrially.
“The multistage nanoreactor catalytic catalyst of the present disclosure is for directly preparing aromatic compounds out of synthesis gas. It consists of a core structure, a shell body, and a core/shell transition layer (as illustrated in FIG. 1). The core layer, an iron-based catalyst with Fischer-Tropsch activation for activating CO, H2 and CO2, and forming a main product from olefin. The shell body is a molecular sieve to form an aromatic hydrocarbon product. Its weight is 0.1% to 80 % of total catalyst weight. The core-shell transition layers are a porous oxide and porous carbon material. Their weight is 0.1% to 35%.
“In one embodiment, the iron-based catalytic with Fischer-Tropsch activity can be supported or unsupported, and may contain or not contain aniliaries.”
“In one embodiment, the molecular Sieve is one or more of ZSM-5 or MCM-22, MCM-50, MCM-49, or SAPO-34 zeolite molecularsieve materials.”
“In one embodiment, the molecular Sieve may contain or not auxiliaries.”
“In one embodiment, the outer surface molecular sieve may have or not a silicon-oxygen compound.”
“In one embodiment, the silica/alumina ratio of zeolite molecular Sieve is preferably between 10 and 500. When auxiliaries have been added, they are P, V. Cr. Mn. Fe. Co. Cu. Zn. Ga. Ge. Mo. Ru. Pd. Ag. W. The weight of auxiliaries is 0.01% – 35% of shell layer weight based on atoms. And the weight silicon-oxygen compound is 0.01% -oxygen layer is from 20% to 20% of the shell layers.
“In one embodiment, the transition layer of the present disclosure is porous. It can be one or more of aluminum oxide (silicon oxide), zirconium oxide (zirconium oxide), magnesium oxide, zinc oxides, titanium oxide, calcium oxide, and zinc oxide. The thickness of the transition layers is 0.1 to 1000nm, preferable 0.5 to 100nm.
“A preparation process for the catalyst according the present disclosure includes the following steps:
“Step 3, mix the powder from step 2 into a solution containing the soluble metal salt by an incipient dryness impregnation or an ion exchanging method or an excess impregnation. The soluble salt should be preferably one or more of the following: nitrate; carbonate; acetate; tungstate or chloride.
“In one embodiment, the present disclosure, step 1 the organic solvent is one of ethanol or propanol.
“In one embodiment of the present disclosure, in step 2, the adopted template is one or more of tetrapropylammonium hydroxide, n-propylamine, isopropylamine, hexamethyleneimine, triethylamine and tetraethylammonium hydroxide; the silicon source is one or more of silicon oxide, sodium silicate, propyl orthosilicate, hexamethyldisiloxane, ethyl orthosilicate and isopropyl orthosilicate; the aluminum source is one or more of alumina, aluminum isopropoxide trihydrate, sodium aluminate, aluminum sulfate, boehmite and gibbsite; and the alkali is one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate and sodium acetate.”
“The present disclosure also reveals a method to apply the catalyst to directly prepare aromatic compounds from synthetic gas.”
“The reaction using catalysts of the present disclosure may be performed in a fluidized or fixed bed reactor. Preferably, a fluidized or fixed bed reactor.”
“The present disclosure offers the following benefits:
“(1) The multistage nanoreactor catalyst in the present disclosure can effectively eliminate the influence of the shell-based molecular sieve upon the core catalyst, increase the conversion rate CO and promote further conversion. The present disclosure provides a catalyst that can be used to prepare aromatic hydrocarbons directly using natural gas-based synthesis gases, including coal-based, biomass, and natural gas-based raw materials. It is particularly suitable for the preparation of light aromatic compounds.
“(2) The multistage catalyst for nanoreactors prepared in this disclosure has a relatively high aromatic hydrocarbon selectivity. It can be more effective at inhibiting heavy and polycyclic aromatic hydrocarbons such as naphthalene and has comparatively low methane selectivity.”
“(3) The catalyst is stable and has good industrial applications prospects.”
“BRIEF DESCRIPTION ABOUT FIGURES”
“FIG. “FIG.
“Examples 1 to 6: Preparation Multistage Nanoreactor Catalyst For Direct Conversion Of Synthesis Gas To Aromatic Compounds”
“Product analysis: The products from the reactor were condensed into a cold trap and the uncondensed parts were analysed on-line using a gaschromatography with TCD/FID detectors. The unreacted CO, formed CH4 and CO2, and the inert gas N2 were separated using a packed column of TDX-01. TCD detected the N2 and used it as an internal standard substance to calculate CO conversion. Separation of C1-C5 hydrocarbons was done using an HP-PLOT/Al2O3 Capillary Column. After reaction, the condensed hydrocarbons were collected and analysed by an additional gas chromatography off line which connected with an FID as well as a HP-1 or HPAP capillary column for further separation of meta-, para- and ortho-xylene.
“where (ACO/AN2 )in and(ACO/AN2 )out are respectively the peak areas ratios of CO and N2 at the outlet and inlet of the reactor.”
“where (ACO2 /AN 2 2)out is the peak area ratio CO2 to nitrogen2. fCO 2 & fCO 2 are the correction factors for CO2 and CO2, respectively.
“(3) The selectivity for CO to be converted to hydrocarbons (SCO-HC) was calculated to: nSCOto HC=100?SCO2”
“Certainly, the CO2-free selectivities for CO converted to CH4, and C2-C6 in the gas phase, respectively, as well as hydrocarbons in the liquid phase, namely, the CO2-free distribution of hydrocarbons, were calculated as follows:
“Where SCO is CH 4, is the selectivity for CH4. (ACH 4/AN 2 )out represents the online TCD peak area CH4 ratio from CH4 to N2. fCH 4 represents the correction factor for CH4.
“Where ACn FID1 is the peak area of on-line Cn(n=2-6) or CH4, respectively; and fCn FID1 is the correction factor of Cn (n=2-6) or CH4 in online FID.
“a”) The CO2-free selectivities for CO converted into total hydrocarbons in liquid phases were calculated as:nSCOto C liquid phase =100?SCOto CH4? ?n=2 6SCO and C n
“Where ACn FID2 represents the off-line peak area for Cn(n>=5), fCn FID2 refers to the correction factors for Cn(n>=5)4 off-line.
“Example 1”
“Example 2”
“Example 3”
“Take 5g of 20 Wt % Fe1 and 20 Wt % SiO2 supported iron-based catalyst prepared by an incipient wetness impregnation process. Mix the sample in 50 mL aluminum isopropoxide trihydrate. Stir continuously. Dry the mixture and then calcine the iron catalyst sample with an Al2O3 coating.
“Example 4”
“Example 5”
“Example 6”
“Examples 7:11: Use of Invented Catalysts to Convert Synthesis Gas To Aromatic Hydrocarbons
Make the catalyst at 6.5 MPa pressure. Then crush the material and sieve it to get a sample of 40-60 meshes. You should add 1.0 g catalyst to a continuous flow reactor. The catalyst was pre-reduced using one or more hydrogen, carbon monoxides, methane, ethane, or ethylene gases for a period of time. After that, the reactor was cooled to the temperature necessary for continuous reaction. For calculating the CO conversion rate, the reaction gas contained 45 vol% CO, 45vol% H2 and four vol% N2. The internal standard gas was N2. A gas chromatograph with a thermal conductivity detector and a hydrogen-ion flame detector was used to analyze the product under atmospheric pressure. The cold trap product was then analyzed off-line by another gaschromatograph with a hydrogen flame detector.
“Example 7”
“Example 8”
“Example 9”
“Example 10”
“Example 11”
“Comparative Example 1”.
“Comparative example 2”
It is evident from the comparison of these examples with the comparative examples in Tables 1, 2 that the catalyst containing transition layer oxide and having the molecular sieve layers being modified internally or externally has a higher selectivity for light aromatic hydrocarbons. The highest BTX selectivity of 76.9% is 76.9%. In particular, the selectivity towards xylene reaches 30% and above. This accounts for between 80 and 90% of the xylene. The catalysts without the molecular sieve layer being modified internally or externally produce more heavy aromatic hydrocarbon products.
“The scope of the disclosure described and claimed in this document is not limited by the particular aspects disclosed. Anyone skilled in the arts can modify the disclosure without affecting its spirit or scope. “The claims should define the scope of protection for the disclosure.
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