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EP-4737001-A1 - POROUS CARBON CARRIER-SUPPORTED CATALYST, PREPARATION METHOD THEREFOR AND USE THEREOF

EP4737001A1EP 4737001 A1EP4737001 A1EP 4737001A1EP-4737001-A1

Abstract

The present invention discloses a porous carbon support-loaded catalyst, a preparation process therefor, and an application thereof. In the catalyst of the present invention, calculated as active metal oxide, the content of the active metal component distributed within pore channels of the porous carbon support accounts for more than 50% relative to the total content of all active metal components in the catalyst. The catalyst of the present invention has stable properties in the system, and its active centers are not easily lost, solving the problems of easy loss of active components of the heterogeneous catalyst and short catalyst life existing in previous technologies. Additionally, when the catalyst of the present invention is used in the preparation of dialkyl carbonates, it exhibits excellent conversion rate and selectivity.

Inventors

  • GE, Junwei
  • YU, Fengping
  • WANG, YI
  • HE, WENJUN

Assignees

  • China Petroleum & Chemical Corporation
  • Sinopec (Shangai) Research Institute of Petrochemical Technology Co., Ltd.

Dates

Publication Date
20260506
Application Date
20240627

Claims (12)

  1. A porous carbon support-loaded catalyst, characterized in that it comprises a porous carbon support, an active metal component, and at least one heteroatom selected from nitrogen, sulfur, and phosphorus, wherein, relative to the total mass of the catalyst, the content of the porous carbon support is 50% to 99%, the content of the active metal component calculated as active metal oxide is 0.1% to 50%, and the content of the heteroatom(s) calculated as element is 0.1% to 5%; said active metal is at least one selected from magnesium, aluminum, and calcium; and calculated as active metal oxide, the content of the active metal component distributed within porous channels of the porous carbon support accounts for more than 50% relative to the total content of all active metal components in the catalyst.
  2. The catalyst according to claim 1, characterized in that the particle size of said porous carbon support is 0.1 mm to 3 mm, preferably 0.3 mm to 2 mm; and the pore size of the porous carbon support is 5 to 500 nm, preferably 50 to 300 nm.
  3. The catalyst according to claim 1 or 2, characterized in that it satisfies at least one of the following conditions: calculated as active metal oxide, the content of the active metal component distributed within porous channels of the porous carbon support accounts for 55% or more, preferably 60% or more, further preferably 65% or more, most preferably 70% or more, relative to the total content of all active metal components in the catalyst; relative to the total mass of the catalyst, the content of the porous carbon support is 55% to 90%, preferably 60% to 85%, and the content of the active metal component calculated as active metal oxide is 5% to 45%, preferably 10% to 40%; and the content of the heteroatom(s) calculated as element is 0.3% to 4.5%, preferably 0.5% to 4%.
  4. The catalyst according to any one of claims 1 to 3, characterized in that , calculated as active metal oxide, the content of the active metal component distributed on the outer surface of the porous carbon support as determined by XPS accounts for less than 50%, preferably 45% or less, more preferably 40% or less, further preferably 35% or less, most preferably 30% or less, relative to the total content of all active metal components in the catalyst.
  5. A process for preparing a porous carbon support-loaded catalyst, comprising the following steps: (1) a modification step, in which a haloalkylated resin is contacted with a modifier to perform a modification, thereby obtaining a modified haloalkylated resin; (2) a contact step, in which the modified haloalkylated resin is contacted with a metal precursor of an active metal, thereby obtaining a contact product; and (3) a calcining step, in which the contact product is optionally dried and then calcined in an inactive gas atmosphere, said modifier is at least one compound selected from nitrogen-containing compounds, sulfur-containing compounds, and phosphorus-containing compounds, and said active metal is at least one selected from magnesium, aluminum, and calcium.
  6. The process according to claim 5, wherein step (1) satisfies at least one of the following conditions: the haloalkylated resin is a halomethylated resin, preferably a chloromethylated resin, more preferably a chloromethylated styrene resin; the modifier is nitrogen-containing organic compounds, sulfur-containing organic compounds or phosphorus-containing organic compounds, preferably alkylamines (for example methylamine, ethylamine, hexylamine, propylamine, dimethylamine, diethylamine), 5- or 6-membered nitrogen-containing heterocyclic aromatic compounds, thiophene compounds or triphenylphosphine, more preferably 5- or 6-membered nitrogen-containing heterocyclic aromatic compounds optionally substituted by C 1 -C 6 alkyl, thiophene compunds optionally substituted by C 1 -C 6 alkyl or triphenylphosphine, particularly preferably at least one of piperazine optionally substituted by C 1 -C 6 alkyl, pyridine optionally substituted by C 1 -C 6 alkyl, imidazole optionally substituted by C 1 -C 6 alkyl, quinoline optionally substituted by C 1 -C 6 alkyl, pyrrole optionally substituted by C 1 -C 6 alkyl, indole optionally substituted by C 1 -C 6 alkyl, carbazole optionally substituted by C 1 -C 6 alkyl, isoindole optionally substituted by C 1 -C 6 alkyl, thiazole optionally substituted by C 1 -C 6 alkyl, thiophene optionally substituted by C 1 -C 6 alkyl, triphenylphosphine; the mass ratio of said haloalkylated resin to the modifier is 1:(0.1-1.2), preferably 1:(0.15-1); the modification step is carried out in a solvent, wherein said solvent is at least one selected from toluene, methanol, ethanol, n-propanol, n-butanol, isobutanol, tert-butanol, tetrahydrofuran, dichloromethane, trichloromethane, N,N-dimethylformamide, ether, and water, and the mass ratio of the haloalkylated resin to the solvent is 1:(1-10), preferably 1:(2-8); the temperature of the modification step is 30°C to 150°C, preferably 40°C to 120°C; the modification time of the modification step is 1 h to 24 h, preferably 2 h to 18 h; the modification step is performed under mixing and stirring, wherein the mixing and stirring rate is 50 rpm to 1000 rpm, preferably 100 rpm to 800 rpm; in the modification step, the obtained modified haloalkylated resin is washed and dried, wherein the drying conditions include: the drying temperature is 80°C to 180°C, the drying time is 1 h to 48 h.
  7. The process according to claim 5 or 6, wherein step (2) satisfies at least one of the following conditions: the metal precursor of the active metal is in at least one form of nitrate, chloride, and sulfate of the active metal; the mass ratio of the modified haloalkylated resin to the metal precursor of the active metal is 1:0.1 to 3, preferably 1:0.2 to 2; the metal precursor of the active metal is kept in form of solution to contact the modified haloalkylated resin obtained in step (1), wherein the solvent is at least one selected from toluene, methanol, ethanol, n-propanol, n-butanol, isobutanol, tert-butanol, tetrahydrofuran, dichloromethane, trichloromethane, N,N-dimethylformamide, ether, and water; step (2) is performed under mixing and stirring conditions, wherein the mixing and stirring rate is 100 rpm to 800 rpm, preferably 200 rpm to 600 rpm; the mixing and stirring temperature is 30°C to 100°C, preferably 50°C to 80°C; and the mixing and stirring time is 1 h to 10 h, preferably 2 h to 8 h.
  8. The process according to any one of claims 5-7, wherein step (3) satisfies at least one of the following conditions: the contact product obtained in step (2) is dried, wherein the drying conditions include: the temperature is 80°C to 180°C, preferably 90°C to 150°C; the time is 1 h to 48 h, preferably 2 h to 36 h; the inactive gas is at least one of nitrogen gas and noble gas; the calcining temperature is 200°C to 1000°C, preferably 250°C to 900°C; and the calcining time is 1 h to 48 h, preferably 2 h to 24 h.
  9. A method for preparing a dialkyl carbonate represented by the following formula (I), characterized in that , in the presence of the catalyst according to any one of claims 1 to 4 or a catalyst prepared by the process according to any one of claims 5 to 8, a carbonate represented by the following formula (II) and a lower alcohol represented by the following formula (III) are reacted to obtain the dialkyl carbonate represented by formula (I); R 1 -OCOO-R 1 (I) in formula (I), each R 1 is independently selected from C 1 -C 6 alkyl; R 2 -OCOO-R 2 (II) in formula (II), each R 2 is independently selected from C 1 -C 6 alkyl, and at least one R 2 is different from at least one R 1 ; or the two R 2 are bonded to each other to form a C 2 -C 6 alkylene group; R 1 -OH (III) in formula (III), R 1 is selected from C 1 -C 6 alkyl.
  10. The method according to claim 9, characterized in that it satisfies at least one of the following conditions: the reaction temperature is 40°C to 130°C, preferably 50°C to 120°C; the reaction time is 1 h to 15 h, preferably 2 h to 12 h.
  11. The method according to claim 9 or 10, characterized in that it satisfies at least one of the following conditions: the molar ratio of the lower alcohol represented by formula (III) to the carbonate represented by formula (II) is (0.5-15):1, preferably (1-12):1; the mass ratio of the catalyst to the carbonate represented by formula (II) is (0.001-0.5):1, preferably (0.05-0.5):1; in formula (I), the two R 1 are identical to each other; and in formula (II), the two R 2 are bonded to each other to form a C 2 -C 6 alkylene group.
  12. The method according to any one of claims 9-11, characterized in that it satisfies at least one of the following conditions: the carbonate represented by formula (II) is at least one of ethylene carbonate and propylene carbonate, the lower alcohol is at least one of methanol, ethanol, propanol, isopropanol, and butanol; the dialkyl carbonate represented by formula (I) is at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, and dibutyl carbonate.

Description

Technical Field The present invention provides a supported catalyst, and more specifically relates to a catalyst in which an active metal component is mainly loaded within the pore channels of a porous carbon support, a preparation method for said catalyst, and an application thereof in the preparation of dialkyl carbonates. Background Technology Dimethyl carbonate (DMC), characterized by its active chemical properties, excellent physical properties, non-toxicity, and ease of biodegradation, is a new, low-pollution, environmentally friendly green basic chemical raw material. It can be used as a solvent, a gasoline additive, a lithium-ion battery electrolyte, and a carbonylation, methylation, or carbomethoxylation reagent, and is widely applied in the chemical and chemical engineering fields. Currently, countries worldwide are actively researching green chemical processes based on this environmentally friendly chemical raw material, DMC. Among them, the transesterification method is superior due to its mild reaction conditions, high yield, and co-production of ethylene glycol or propylene glycol, making it a highly promising industrial approach. Generally, alkali metal hydroxides, alkali metal carbonates, alkali metal alkoxides, etc. are used as catalysts in transesterification reactions (US2011040117A1; WO2010063780A1). However, because they are homogeneous catalysts, they are difficult to separate from the products, leading to challenges in reuse. Commonly used heterogeneous catalysts include alkali metals or alkali metal salts supported on supports, metal oxide catalysts, alkali (earth) metal-exchanged zeolites or clay materials, ion exchange resins and the like. Alkali metals or alkali metal salts supported on supports, such as KF/Al2O3, NaOH/chitosan, and Cs2CO3/SiO2-Al2O3 (CN101249452A; CN101121147A; WO2001056971A1), have the disadvantage of being easily affected by water and CO2 in the air and easily lost during the reaction, resulting in decreased activity. Metal oxide catalysts, such as Al2O3 and MgO (US2005080287A1; US6207850B1), and alkali (earth) metal-exchanged zeolites or clay materials, such as Cs-ZSM-5 and Mg-smectite (WO2000073256A1), have the disadvantage of generally low activity or selectivity. Ion exchange resins, such as quaternary ammonium-type or tertiary amine-type resins, are usually not resistant to high temperatures or swelling, and their activity decreases rapidly over time. Therefore, finding a catalyst with high stability and high conversion rate for the preparation of dialkyl carbonates remains an urgent need in this field. Summary of the Invention In view of the above situation, the inventors of the present invention conducted in-depth research and surprisingly found that by loading an active metal component onto a modified resin support and then calcining the resin support, a catalyst in which the active metal component is mainly distributed within the pore channels of a porous carbon support can be obtained. This catalyst exhibits excellent stability and high catalytic activity, thereby completing the present invention. Specifically, a first aspect of the present invention provides a porous carbon support-loaded catalyst, characterized in that it comprises a porous carbon support, an active metal component, and at least one heteroatom selected from nitrogen, sulfur, and phosphorus, wherein, relative to the total mass of the catalyst, the content of the porous carbon support is 50% to 99%, the content of the active metal component calculated as active metal oxide is 0.1% to 50%, and the content of the heteroatom(s) calculated as element is 0.1% to 5%; said active metal is at least one selected from magnesium, aluminum, and calcium; and calculated as active metal oxide, the content of the active metal component distributed within porous channels of the porous carbon support accounts for more than 50% relative to the total content of all active metal components in the catalyst. A second aspect of the present invention provides a process for preparing a catalyst, comprising the following steps: (1) a modification step, in which a haloalkylated resin is contacted with a modifier to perform a modification, thereby obtaining a modified haloalkylated resin;(2) a contact step, in which the modified haloalkylated resin is contacted with a metal precursor of an active metal, thereby obtaining a contact product; and(3) a calcining step, in which the contact product is optionally dried and then calcined in an inactive gas atmosphere. A third aspect of the present invention provides a method for preparing a dialkyl carbonate, wherein a carbonate and a lower alcohol are reacted in the presence of the aforementioned catalyst of the present invention or a catalyst prepared by the preparation process of the present invention to obtain the dialkyl carbonate. Technical effect In the catalyst of the present invention, compared to the active metal component distributed on the surface of the poro