AU2018446680B2

AU2018446680B2 - Hydrogenation catalyst and preparation and uses thereof

Info

Publication number: AU2018446680B2
Application number: AU2018446680A
Authority: AU
Inventors: Libin YAN
Original assignee: Pujing Chemical Industry Co Ltd
Current assignee: Pujing Chemical Industry Co Ltd
Priority date: 2018-10-22
Filing date: 2018-10-22
Publication date: 2023-07-06
Anticipated expiration: 2038-10-22
Also published as: WO2020082196A1; RU2706684C1; AU2018446680A1

Abstract

A hydrogenation catalyst is disclosed. The catalyst comprises an active component in the form of nanoparticles comprising copper or a cooper oxide; an auxiliary agent in the form of nanoparticles comprising an element selected from the group consisting of nickel, cobalt, manganese, zinc, aluminum, zirconium, cerium, lanthanum, molybdenum, barium, vanadium, titanium, iron, yttrium, niobium, tungsten, tin, bismuth, strontium, boron and phosphorus; and a carrier in the form of hollow silica microspheres having microsphere surfaces, wherein the nanoparticles of the active component and the nanoparticles of the auxiliary dispersed on the microsphere surfaces. The hydrogenation catalyst is useful for hydrogenating an oxalate to ethylene glycol, providing a high oxalate conversion rate, a high selectivity for ethylene glycol, strong stability and high yield. Preparation and uses of the catalyst are also disclosed.

Description

HYDROGENATION CATALYST AND PREPARATION AND USES THEREOF

FIELD OF THE INVENTION

The invention relates to a catalyst in the field of organic synthesis, in particular to a catalyst for gas phase hydrogenation of an oxalate to ethylene glycol, and preparation and uses thereof.

BACKGROUND OF THE INVENTION

Ethylene glycol is an important basic organic chemical material, which can react with terephthalic acid (PTA) to form polyethylene terephthalate (PET) , also known as a polyester resin that is the raw material for polyester fiber and polyester plastic. This is the main use of ethylene glycol. Ethylene glycol can also be used directly as an antifreeze and as a coolant for engine preparation. Ethylene glycol dinitrate can be used as an explosive, as well as an indispensable substance in plasticizers, paints, adhesives, surfactants, explosives and capacitor electrolytes. The current industrial route for the production of ethylene glycol is to produce ethylene oxide from petroleum ethylene by gas phase oxidation through a petroleum route, and then hydrated to produce an ethylene glycol product. However, in view of the resource structure of “poor oil, less gas and rich coal” in China, the large-scale production of ethylene glycol products through the petroleum route affects the production of ethylene and other chemical products, and thus developing methods for producing ethylene glycol from syngas has practical significance and strategic impact in China.

Among the reports on the various synthesis processes for ethylene glycol, the process route involving synthesizing oxalic acid diester by CO and then hydrogenating oxalic acid diester to ethylene glycol has gradually matured. By the end of 2009, a 200,000-ton industrial demonstration unit was completed in the high-tech development zone in Tongliao City of the Inner Mongolia Autonomous Region and successfully produced qualified ethylene glycol products, proclaiming that the coal-based ethylene glycol technology has officially moved towards large-scale industrialization.

One of the key technologies for producing ethylene glycol from coal-based syngas is the development of a catalyst for hydrogenation of an oxalate to ethylene glycol. The Institute of Fujian Institute of Physical Science, Chinese Academy of Sciences, East China University of Science and Technology, Zhejiang University, Tianjin University and other related research institutions have started research on oxalate hydrogenation catalysts since 1980s. A model test of hydrogenation of diethyl oxalate was carried out by using Cu-Cr catalyst at 208-230 ℃ and 2.5-3.0 MPa. The reaction result showed 99.8%conversion of diethyl oxalate. With an average selectivity of 95.3%, the catalyst can run for 1134 hours. Chinese Patent No. 101342489A discloses a copper-silicon-based hydrogenation catalyst containing an auxiliary agent, which is selected from one or more of an alkaline earth metal, a transition metal element or a rare earth metal element, for a conversion rate of raw materials over 99%, and selectivity of ethylene glycol more than 95%under a reaction pressure of 3.0 MPa and a polybasic acid ester liquid at a time-space velocity of 0.7 h ^-1. Chinese Patent No. 101138725B discloses a catalyst for hydrogenating an oxalate ester to synthesize ethylene glycol and a preparation method thereof, which comprises copper element as an active component and zinc element as an auxiliary agent, which is prepared by an impregnation method, and provides a conversion rate for the oxalate at about 95%and an ethylene glycol selectivity of about 90%. Chinese Patent No. 102350348B discloses a copper-based catalyst for preparing ethylene glycol by hydrogenation of an oxalate and a preparation method thereof. For the catalyst , the copper element is used as an active component, and a mesoporous silicon shell is used as a carrier, which is completed by in-situ compounding. The oxalic acid ester conversion rate is 99%or more, and the ethylene glycol selectivity is 94%or more.

In the existing catalysts for the hydrogenation of an oxalate to ethylene glycol, most active components are copper, and the content of the active metal copper are mostly relatively high. The excessive copper content tends to cause the growth of surface copper crystals and the activity and thus reducing the activity and lifespan of the catalyst and making long-term industrial plant operation unsatisfactory.

There remains a need for catalysts that are active and stable for producing ethylene glycol.

SUMMARY OF THE INVENTION

The present invention provides a hydrogenation catalyst for producing ethylene glycol by hydrogenating an oxalate and preparation and uses thereof.

A catalyst for producing ethylene glycol by hydrogenating an oxalate is provided. The catalyst comprises an active component in the form of nanoparticles comprising copper or a cooper oxide; an auxiliary agent in the form of nanoparticles comprising an element selected from the group consisting of nickel, cobalt, manganese, zinc, aluminum, zirconium, cerium, lanthanum, molybdenum, barium, vanadium, titanium, iron, yttrium, niobium, tungsten, tin, bismuth, strontium, boron and phosphorus; and a carrier in the form of hollow silica microspheres having microsphere surfaces, wherein the nanoparticles of the active component and the nanoparticles of the auxiliary dispersed on the microsphere surfaces.

The catalyst may have a specific surface area of 100-1200 m ²/g. The catalyst may comprise the active agent at a content of 5-35 wt%. The catalyst may comprise the auxiliary agent at a content of 0.01-20 wt%. The oxalate may be dimethyl oxalate, diethyl oxalate, or a combination thereof.

A process for preparing the catalyst for producing ethylene glycol by hydrogenating an oxalate. The process comprises (a) adding a copper solution and an element precursor/dispersant solution to form Solution III; (b) adding cetyltrimethylammonium bromide (CTAB) , a templating agent and then ammonia water to a carrier precursor solution to form Mixture IV; (c) adding Solution III to Mixture IV in the presence of nitrogen gas and heat to form a reaction product; (d) dehydrating the reaction product to generate precipitates; (e) washing and drying the precipitates to form a cured product; and (f) calcining the cured product, whereby a catalyst having a hollow silica microsphere structure is obtained.

The element precursor/dispersant solution may have a pH of 1.0-7.0. The process may further comprise adding an element precursor to deionized water to form an element precursor solution, and adding a dispersant to the element precursor solution to form the element precursor/dispersant solution. The element may be selected from the group consisting of nickel, cobalt, manganese, zinc, aluminum, zirconium, cerium, lanthanum, molybdenum, barium, vanadium, titanium, iron, yttrium, niobium, tungsten, tin, bismuth, strontium, boron and phosphorus. The dispersant may be selected from the group consisting of citric acid, ammonium citrate, acetic acid, ammonium acetate, malonic acid, succinic acid, tartaric acid, glucose and oxalic acid.

The process may further comprise dissolving a soluble copper salt in deionized water to form the copper solution. The soluble copper salt may be selected from the group consisting of copper nitrate, copper acetate, copper chloride and copper oxalate.

The process may further comprise dissolving a carrier precursor in a mixture of anhydrous ethanol and deionized water to form the carrier precursor solution. The carrier precursor may be selected from the group consisting of silica sol, methyl orthosilicate, tetraethyl orthosilicate, propyl orthosilicate and butyl orthosilicate.

The templating agent may be a hard templating agent maintained by a covalent bond. The hard templating agent may be selected from the group consisting of polystyrene, phenolic resin, porous silicon, activated carbon, polymethyl methacrylate, and bisphenol A epoxy resin.

A method for producing ethylene glycol is provided. The method comprises hydrogenating an oxalate to ethylene glycol in the presence of hydrogen and the catalyst of the present invention. The oxalate may be converted at an average rate of at least 99.0%for at least 2,000 hour. The catalyst may have an average selectivity of at least 95.0%for ethylene glycol for at least 2,000 hour. The ethylene glycol may be produced at an average yield of at least 600.0 mg/g cat/h for least 2,000 hours. The oxalate may be dimethyl oxalate. The catalyst may have an average particle size of 250-850 μm.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a catalyst for hydrogenation of an oxalate to ethylene glycol and preparation and uses thereof. The catalyst comprises an active component, an auxiliary agent and a carrier. The inventors have surprisingly discovered that a hard templating agent may be introduced to prepare a catalyst having a hollow silica microsphere structure such that the catalyst has a high specific surface area. The metal particles of the active component are dispersed on the surface of the silica microspheres, thereby reducing metal loading. The inventors have also surprisingly discovered that a dispersant may be used promote migration of active nanoparticles among the active component, the auxiliary agent and the carrier such that the binding force among the active metal, the auxiliary agent and the carrier is improved, the possibility of sintering and aggregation of the active metal is reduced, and the stability of the catalyst is strengthened. The hydrogenation catalyst of the invention may be used for hydrogenating an oxalate to ethylene glycol, providing a high oxalate conversion rate, a high selectivity for ethylene glycol, and strong stability, and therefore is suitable for industrial applications.

A catalyst for producing ethylene glycol by hydrogenating an oxalate is provided. The catalyst comprises an active component, an auxiliary agent and a carrier. The oxalate may be dimethyl oxalate, diethyl oxalate, or a combination thereof. In one embodiment, the catalyst consists of the active component, the auxiliary agent and the carrier. The catalyst may have a specific surface area of about 100-1200 m ²/g, preferably about 170-1070 m ²/g, more preferably about 210 to 980 m ²/g.

The term “active component” used herein refers to a substance in the catalyst that catalyzes hydrogenation of an oxalate to ethylene glycol. The active component may account for about 5-35 wt%, preferably about 7.5-34%, more preferably about 11-34%, of the catalyst. The active component may be in the form of nanoparticles. A soluble copper salt may be used to provide the active component in the catalyst. The soluble copper salt may be copper nitrate, copper acetate, copper chloride or copper oxalate, preferably copper nitrate, copper acetate or copper chloride, more preferably copper nitrate or copper chloride. A copper solution (Solution II) may be prepared by dissolving a soluble copper salt in deionized water. Solution II may comprise the copper salt at a concentration in the range of about 0.001-2.000 g/mL, based on the total weight of the solution

The term “auxiliary agent” used herein refers to a substance in the catalyst that promotes the interaction between an active component and a carrier in a catalyst. The auxiliary agent may be an element selected from the group consisting of nickel, cobalt, manganese, zinc, aluminum, zirconium, cerium, lanthanum, molybdenum, barium, vanadium, titanium, iron, yttrium, niobium, tungsten, tin, bismuth, strontium, boron and phosphorus. The auxiliary agent may account for about 0.01-20%, preferably about 0.15-18%, more preferably about 0.35-14%, of the catalyst. The active component may be in the form of nanoparticles.

The term “element precursor” used herein refers to a substance of an element for providing the auxiliary agent in the catalyst. The element may be selected from the group consisting of nickel, cobalt, manganese, zinc, aluminum, zirconium, cerium, lanthanum, molybdenum, barium, vanadium, titanium, iron, yttrium, niobium, tungsten, tin, bismuth, strontium, boron and phosphorus. The element precursor may be an oxo acid, a chloride, a nitrate salt, an acetate salt, an oxalate salt, or an ammonium salt, preferably a chloride, a nitrate salt, an acetate salt or an ammonium salt, more preferably a chloride, a nitrate salt or an ammonium salt. An element precursor mixture may be prepared by adding an element precursor to deionized water. The element precursor mixture may comprise the element precursor at a concentration in the range of about 0.0001-1.0000 g/mL, based on the total weight of the mixture.

The term “carrier” used herein refers to a substance in the catalyst that provides support for the active component and the auxiliary agent. The carrier comprises one or more hollow silica microspheres. The hollow silica microspheres may be formed by silica via covalent bonds. The microspheres may have an average particle diameter of about 50-5000 nm, preferably about 100-2500 nm, more preferably about 150-1050 nm. The microspheres may comprise a shell that encompasses a hollow structure. The microspheres may have an average outer shell thickness of about 5-500 nm, preferably about 10-350 nm, more preferably about 20-210 nm.

The active component nanoparticles and the auxiliary agent nanoparticles are dispersed on the surface of the microsphere. For example, the active component nanoparticles and the auxiliary agent nanoparticles are dispersed on the surface of the microsphere.

The term “carrier precursor” used herein refers to a substance in the carrier precursor solution used to provide a carrier in the catalyst. The precursor of the carrier is at least one of silica sol, methyl orthosilicate, tetraethyl orthosilicate, propyl orthosilicate or butyl orthosilicate, preferably silica sol, methyl orthosilicate or tetraethyl orthosilicate, more preferably silica sol or tetraethyl orthosilicate. A carrier precursor solution may be prepared by dissolving a carrier precursor in a mixture of anhydrous ethanol and deionized water. The carrier precursor solution may comprise the carrier precursor at a concentration in the range of about 0.001-1.000 g/mL, based on the total weight of the solution. The carrier precursor solution may have a pH in the range of about 1.0-7.0.

The term “dispersant” used herein refers to a substance that promotes migration of active nanoparticles among the active component, the auxiliary agent, and the carrier. The dispersant may be selected from the group consisting of citric acid, ammonium citrate, acetic acid, ammonium acetate, malonic acid, succinic acid, tartaric acid, glucose or oxalic acid, preferably citric acid and ammonium citrate, preferably selected from the group consisting of ammonium acetate, malonic acid, tartaric acid and glucose, more preferably selected from the group consisting of at least one of citric acid, ammonium acetate, tartaric acid and glucose. An element precursor/dispersant solution (Solution I) may be prepared by adding a dispersant to an element precursor mixture. Solution I having a pH in the range of about 1.0-7.0. Solution I may comprise element precursor at a concentration in the range of about 0.0001-1.0000 g/mL, and/or the dispersant at a concentration in the range of about 0.0001-1.0000g/mL.

The term “templating agent” used herein refers to a substance that acts as a structure guide in catalyst synthesis. The templating may be a hard templating agent maintained by a covalent bond. The hard templating agent may be polystyrene, phenolic resin, porous silicon, activated carbon, polymethyl methacrylate, and bisphenol A epoxy resin, preferably polystyrene, phenolic resin, activated carbon, or polymethyl methacrylate, more preferably polystyrene, phenol resin, or activated carbon.

For each catalyst of the present invention, a process for preparing the catalyst is provided. The process comprises (a) adding a copper solution (Solution II) to an element precursor/dispersant solution (Solution I) to form Solution III; (b) adding cetyltrimethylammonium bromide (CTAB) , a templating agent and ammonia water to a carrier precursor solution to obtain Mixture IV; (c) adding Solution III to Mixture IV in the presence of nitrogen gas and heat to form a reaction product; (d) dehydrating the reaction product to generate precipitates; (e) washing and drying the precipitates to form a cured product; and (f) calcining the cured product. As a result, a catalyst having a hollow silica microsphere structure is obtained.

In step (1) , the copper solution (Solution II) may be added to the element precursor/dispersant solution (Solution I) dropwise at a constant speed while being continuously stirred vigorously to form Solution III.

In step (2) , the cetyltrimethylammonium bromide (CTAB) and the templating agent may be added to the carrier precursor solution, and stirred at about 30-50 ℃ for about 20-60 min before ammonia water is added, stirred vigorously at about 30-60 ℃ for about 1-6h, to obtain Mixture IV. In Mixture IV, the mass ratio of carrier precursor : absolute ethanol: deionized water: cetyltrimethylammonium bromide (CTAB) : the templating agent: ammonia water may be about 1: (0.1-50) : (0.1-50) : (0.01-1.0) : (0.01-5.0) : (0.01-20.0) .

In step (3) , nitrogen gas may be introduced to the mixture of Solution III and Mixture IV for about 5-60 minutes while the mixture is continuously stirring vigorously and heated to about 40-70 ℃ for about 1-24 hours to form the reaction product.

In step (4) , the reaction product may be dehydrated by centrifugation to generate precipitates.

In step (5) , the precipitates may be washed thoroughly with deionized water and dried at about 50-110 ℃ under about 80-90 kPa for about 2-24 h to form the cured product.

In step (6) , the cured product may be calcined in air at about 350-700 ℃ for about 2-8 h.

A method for producing ethylene glycol is provided. The method comprises hydrogenating an oxalate in the presence hydrogen and the catalyst of the present invention. The oxalate may be dimethyl oxalate, diethyl oxalate, or a combination thereof. For example, the catalyst may be used for hydrogenation of dimethyl oxalate to ethylene glycol. The catalyst may be compressed, extruded, sprayed, and rotated into a particle shape of about 1-6 mm, for example, cylindrical , spherical, ellipsoidal, toroidal, honeycomb, gear-shaped, clover-shaped and four-leaf clover, crushed and sieved to about 20-60 mesh. The catalyst may have an average particle size from about 250 μm to about 850 μm.

The calcined catalyst is compressed. The reaction may be performed in a fixed bed reactor unit under reducing conditions. The reduction conditions may include a gas mixture of nitrogen and hydrogen comprising hydrogen at about 5%by volume, based on the total volume of the gas mixture, a temperature of about 180-300℃, and a gas time-space velocity of about 500-1500 h ^-1 for about 6-30 h. The reaction conditions may include a temperature at about 170-210 ℃, a pressure at about 1-3.5 MPa, a molar ratio of the hydrogen to the ester at about 30-120, a methanol solution comprising dimethyl oxalate at about 5-100%by weight, based on the total weigh of the methanol solution, at a liquid time-space velocity of 0.5-3.0 h ^-1.

The hydrogenation catalyst of the invention has a hollow silica microsphere structure and provides a high oxalate conversion rate, a high selectivity for ethylene glycol, strong stability and high yield of ethylene glycol.

The term “conversion rate” used herein refers to the percentage of an oxalate that is converted to a product. The average conversion rate of the catalyst according to the present invention may be at least about 98.0%, 98.5%, 99.0%, 99.5%, 99.9%or 100%for period of time, for example, at least 500, 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 7,000, 8,000, 9,000 or 10,000 hours. The average oxalate conversion rate may be at least about 1%, 2%, 3%, 4%or 5%higher for period of time, for example, at least about 500, 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 7,000, 8,000, 9,000 or 10,000 hours using the catalyst of the present invention as compared with that using a catalyst having a specific surface area below about 1, 10 or 100 m ²/g or a catalyst prepared by a process without the use of a dispersant, a templating agent or a combination thereof.

The term “selectivity” used herein refers to percentage of an oxalate converted to a target product in all of the converted oxalate. The average selectivity of the catalyst for ethylene glycol according to the present invention may be at least about 95.0%, 96.0%, 97.0%, 98.0%, 99.0%, 99.5%, 99.9%or 100%for period of time, for example, at least about 500, 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 7,000, 8,000, 9,000 or 10,000 hours. The average selectivity rate of the catalyst for ethylene glycol may be at least about 1%, 2%, 3%, 4%or 5%higher for period of time, for example, at least about 500, 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 7,000, 8,000, 9,000 or 10,000 hours using the catalyst of the present invention as compared with that using a catalyst having a specific surface area below about 1, 10 or 100 m ²/g or a catalyst prepared by a process without the use of a dispersant, a templating agent or a combination thereof.

The term “time-space yield of ethylene glycol” used herein refers to the production amount of ethylene glycol per unit mass of a catalyst per unit time. The average yield of ethylene glycol according to the present invention may be at least about 500, 600, 700, 800, 900 or 1,000 mg/g cat/h for period of time, for example, at least about 500, 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 7,000, 8,000, 9,000 or 10,000 hours. The average yield of ethylene glycol may be at least about 50, 100, 200, 300, 400,500, 600, 700, 800, 900 or 1,000 mg/g cat/h higher for period of time, for example, at least about 500, 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 7,000, 8,000, 9,000 or 10,000 hours using the catalyst of the present invention as compared with that using a catalyst having a specific surface area below about 1, 10 or 100 m ²/g or a catalyst prepared by a process without the use of a dispersant, a templating agent or a combination thereof.

The term “about” as used herein when referring to a measurable value such as an amount, a percentage, and the like, is meant to encompass variations of ±20%or ±10%, more preferably ±5%, even more preferably ±1%, and still more preferably ±0.1%from the specified value, as such variations are appropriate.

Example 1.

Catalysts 1-11 and Comparative Catalysts 1-4 were prepared. The content of the active component for each catalyst was measured by ICP (Tables 1 and 2) . The specific surface area of each catalyst was measured by a physicochemical adsorption meter (Table 1) . The particle size and shell wall thickness of hollow silica microspheres were measured by scanning electron microscopy (Table 1) . The catalytic activities (e.g., dimethyl oxalate conversion rate and selectivity for ethylene glycol) for each catalyst were determined in a hydrogenation reaction of dimethyl oxalate to produce ethylene glycol (Table 2) . In the hydrogenation reaction, a methanol solution comprising dimethyl oxalate was used as the raw material for Catalysts 1-10 and Comparative Catalysts 1-3, while dimethyl oxalate was used as the raw material for Catalyst 11 and Comparative Catalyst 4.

Catalyst 1

Catalyst 1 was prepared according to a preparation method comprising the following steps:

(1) dissolving 2.55g cobalt nitrate in 100ml deionized water, adding 14.22g citric acid, and adjusting the pH to 3.5 to obtain Solution I;

(2) dissolving 9.81g copper nitrate in 200ml deionized water to obtain Solution II; and then adding Solution II to Solution I at a steady speed while stirring vigorously to form Solution III;

(3) dissolving 19.40 g ethyl orthosilicate 32 in 150 ml absolute ethanol and 50 ml of deionized water, adding 6.44 g cetyltrimethylammonium bromide (CTAB) and 7.82 g polystyrene microspheres as a templating agent, stirring at 40 ° C for 40 min, then adding 73.54g ammonia water, stirring vigorously at 50 ℃ for 4h, to obtain Mixture IV;

(4) adding solution III to Mixture IV, introducing nitrogen gas for 30 minutes while continuously stirring vigorously, heating to 65 ℃ for 12 hours, dehydrating the reaction product by centrifugation, and washing thoroughly with deionized water at 80 ℃ and under 85 kPa; drying for 8 hours to obtain a cured product, baking the cured product in air at 500 ℃ for 4 hours to obtain Catalyst 1 having a hollow silica microsphere structure.

The catalytic activity of Catalyst 1 was determined in the following hydrogenation reaction: Catalyst 1 was tableted, crushed, and sieved to 20-60 mesh, using a fixed bed reactor apparatus under reducing conditions of a gas mixture of nitrogen and hydrogen containing 5%hydrogen at 220 ℃ and with a volumetric time-space velocity of 700 h ^-1 for 24 hours; the reaction temperature was 185 ° C; the reaction pressure was 2.0 MPa; the hydrogen to ester molar ratio was 80; and the liquid time-space velocity of a methanol solution containing dimethyl oxalate at 80%by weight, based on the total weigh to the methanol solution, was 1.5 h ^-1.

Comparative Catalyst 1

Comparative catalyst 1 was prepared according to the process of Catalyst 1, except that dispersant citric acid was not added in step (1) . The catalytic activity evaluation conditions were the same as in Catalyst 1.

Catalyst 2

Catalyst 2 was prepared according to the process of Catalyst 1 except that polystyrene microspheres in the step (3) were changed to activated carbon and cobalt nitrate was changed to Ni nitrate.

The catalytic activity of Catalyst 2 was determined in the following hydrogenation reaction: Catalyst 2 was tableted, crushed, and sieved to 20-60 mesh, using a fixed bed reactor apparatus under reducing conditions of a gas mixture of nitrogen and hydrogen containing 5%hydrogen at 240 ℃ and with a volumetric time-space velocity of 1,000 h ^-1 for 24 hours; the reaction temperature was 200 ° C; the reaction pressure was 1.5 MPa; the hydrogen to ester molar ratio was 100; and the liquid time-space velocity of a methanol solution containing dimethyl oxalate at 50%by weight, based on the total weigh to the methanol solution, was 2.0 h ^-1.

Comparative example 2

Comparative catalyst 2 was prepared according to the process of Catalyst 2, except that the activated carbon was not added in step (3) . The catalytic activity evaluation conditions were the same as in Example 2.

Catalyst 3

Catalyst 3 was prepared according to the process of Catalyst 1 except that the polystyrene microspheres in the step (3) were changed to phenolic resin and cobalt nitrate was changed to Ce nitrate.

The catalytic activity of Catalyst 3 was determined in the following hydrogenation reaction: Catalyst 3 was tableted, crushed, and sieved to 20-60 mesh, using a fixed bed reactor apparatus under reducing conditions of a gas mixture of nitrogen and hydrogen containing 5%hydrogen at 200 ℃ and with a volumetric time-space velocity of 1,200 h ^-1 for 20 hours; the reaction temperature was 195 ° C; the reaction pressure was 2.5 MPa; the hydrogen to ester molar ratio was 120; and the liquid time-space velocity of a methanol solution containing dimethyl oxalate at 75%by weight, based on the total weigh to the methanol solution, was 1.0 h ^-1.

Comparative Catalyst 3

Comparative catalyst 3 was prepared according to the process of Catalyst 3, except that dispersant citric acid was not added in step (1) and phenolic resin is not added in the step (3) . The catalytic activity evaluation conditions were the same as in Example 3.

Catalyst 4

Catalyst 4 was prepared according to the process of Catalyst 1 except that the polystyrene microspheres in the step (3) were changed to porous silicon and cobalt nitrate was changed to La nitrate.

The catalytic activity of Catalyst 4 was determined in the following hydrogenation reaction: Catalyst 4 was tableted, crushed, and sieved to 20-60 mesh, using a fixed bed reactor apparatus under reducing conditions of a gas mixture of nitrogen and hydrogen containing 5%hydrogen at 210 ℃ and with a volumetric time-space velocity of 800 h ^-1 for 22 hours; the reaction temperature was 205 ° C; the reaction pressure was 2.0 MPa; the hydrogen to ester molar ratio was 60; and the liquid time-space velocity of a methanol solution containing dimethyl oxalate at 95%by weight, based on the total weigh to the methanol solution, was 1.2 h ^-1.

Catalyst 5

Catalyst 5 was prepared according to the process of Catalyst 1 except that the polystyrene microspheres in the step (3) were changed to polymethyl methacrylate and cobalt nitrate was changed to Mo ammonium salt.

The catalytic activity of Catalyst 5 was determined in the following hydrogenation reaction: Catalyst 5 was tableted, crushed, and sieved to 20-60 mesh, using a fixed bed reactor apparatus under reducing conditions of a gas mixture of nitrogen and hydrogen containing 5%hydrogen at 220 ℃ and with a volumetric time-space velocity of 1,000 h ^-1 for 10 hours; the reaction temperature was 175 ° C; the reaction pressure was 3.5 MPa; the hydrogen to ester molar ratio was 120; and the liquid time-space velocity of a methanol solution containing dimethyl oxalate at 100%by weight, based on the total weigh to the methanol solution, was 0.8 h ^-1.

Catalyst 6

Catalyst 6 was prepared according to the process of Catalyst 1 except that the polystyrene microspheres in the step (3) were changed to bisphenol A epoxy resin and cobalt nitrate was changed to Mn nitrate.

The catalytic activity of Catalyst 6 was determined in the following hydrogenation reaction: Catalyst 6 was tableted, crushed, and sieved to 20-60 mesh, using a fixed bed reactor apparatus under reducing conditions of a gas mixture of nitrogen and hydrogen containing 5%hydrogen at 190 ℃ and with a volumetric time-space velocity of 1,500 h ^-1 for 20 hours; the reaction temperature was 190 ° C; the reaction pressure was 2.5 MPa; the hydrogen to ester molar ratio was 100; and the liquid time-space velocity of a methanol solution containing dimethyl oxalate at 25%by weight, based on the total weigh to the methanol solution, was 2.0 h ^-1.

Catalyst 7

Catalyst 7 was prepared according to the process of Catalyst 1 except that the citric acid in the step (1) was changed to glucose and cobalt nitrate was changed to Zr nitrate.

The catalytic activity of Catalyst 7 was determined in the following hydrogenation reaction: Catalyst 7 was tableted, crushed, and sieved to 20-60 mesh, using a fixed bed reactor apparatus under reducing conditions of a gas mixture of nitrogen and hydrogen containing 5%hydrogen at 230 ℃ and with a volumetric time-space velocity of 1,200 h ^-1 for 24 hours; the reaction temperature was 195 ° C; the reaction pressure was 2.0 MPa; the hydrogen to ester molar ratio was 110; and the liquid time-space velocity of a methanol solution containing dimethyl oxalate at 60%by weight, based on the total weigh to the methanol solution, was 1.8 h ^-1.

Catalyst 8

Catalyst 8 was prepared according to the process of Catalyst 1 except that the citric acid added in the step (1) was changed to tartaric acid and cobalt nitrate was changed to Zn nitrate.

The catalytic activity of Catalyst 8 was determined in the following hydrogenation reaction: Catalyst 8 was tableted, crushed and sieved to 20-60 mesh, using a fixed bed reactor unit, reducing conditions of 240 ℃, volumetric time-space velocity of 1,000 h ^-1, mixing with nitrogen and hydrogen containing 5%of hydrogen The gas was reduced for 22 h;the reaction condition was 180 ℃, the pressure was 3.0 MPa, the hydrogen ester molar ratio was 120, and the liquid time-space velocity of the methanol solution containing dimethyl oxalate having a mass concentration of 90%was 1.1 h ^-1.

Catalyst 9

Catalyst 9 was prepared according to the process of Catalyst 1 except that the citric acid added in the step (1) was changed to ammonium acetate and cobalt nitrate was changed to Al nitrate and boric acid.

The catalytic activity of Catalyst 9 was determined in the following hydrogenation reaction: Catalyst 9 was tableted, crushed and sieved to 20-60 mesh, using a fixed bed reactor unit, reducing conditions of 200 ℃, volumetric time-space velocity of 1, 100 h ^-1, mixing with nitrogen and hydrogen containing 5%of hydrogen. The gas was reduced for 16 h;the reaction condition was 210 ℃, the pressure was 1.5 MPa, the hydrogen ester molar ratio was 90, and the liquid time-space velocity of the methanol solution containing dimethyl oxalate having a mass concentration of 55%was 0.7 h ^-1.

Catalyst 10

Catalyst 10 was prepared according to the process of Catalyst 1 except that the citric acid added in the step (1) was changed to malonic acid and cobalt nitrate was changed to Ba nitrate and ammonium hydrogen phosphate.

The catalytic activity of Catalyst 10 was determined in the following hydrogenation reaction: Catalyst 10 was tableted, crushed and sieved to 20-60 mesh, using a fixed bed reactor unit, reducing conditions of 280 ℃, volumetric time-space velocity of 900 h ^-1, mixing with nitrogen and hydrogen containing 5%of hydrogen. The gas was reduced for 30 h; the reaction condition was 170 ℃, the pressure was 1.0 MPa, the hydrogen ester molar ratio was 30, and the liquid time-space velocity of the methanol solution containing dimethyl oxalate having a mass concentration of 55%was 0.7 h ^-1.

Catalyst 11

Catalyst 11 was prepared according to the process of Catalyst 1 except that cobalt nitrate was changed to Bi nitrate and La nitrate .

The catalytic activity of Catalyst 11 was determined in the following hydrogenation reaction: Catalyst 11 was tableted, crushed and sieved to 20-60 mesh, using a fixed bed reactor unit, reducing conditions of 230 ℃, volumetric time-space velocity of 800 h ^-1, mixing with nitrogen and hydrogen containing 5%of hydrogen. The gas was reduced for 24 h; the reaction condition was 185-195 ℃, the pressure was 2.5 MPa, the hydrogen ester molar ratio was 80-100, and the liquid time-space velocity of dimethyl oxalate was 1.0-2.0 h ^-1.

A liquid sample was taken every hour to analyze the product composition by gas chromatography, and the conversion rate of dimethyl oxalate and the selectivity for ethylene glycol were calculated. The reaction was stable for 6000 h, and the activity of the catalyst was not significantly reduced. The average conversion rate of dimethyl oxalate reached 99.9%, the average selectivity for ethylene glycol was over 96.5%, and the average yield of ethylene glycol was as high as 759.8 mg/g cat/h. The catalyst showed an excellent hydrogenation activity, ethylene glycol selectivity and stability, and is suitable for long-term industrial applications.

Comparative Catalyst 4

Comparative Catalyst 4 was prepared according to the process of Catalyst 11 except that the dispersant citric acid was not added in the step (1) and the polystyrene microspheres were not added in the step (3) . The catalyst activity evaluation conditions were the same as for Catalyst 11. After 2000 h of reaction, the activity of the catalyst decreased significantly. The conversion rate of dimethyl oxalate decreased from 97.8%to 93.9%, and the selectivity of ethylene glycol decreased from 94.6%to 88.7%. The average yield of ethylene glycol was only 583.3 mg/g cat/h.

Table 1. Composition and Characteristics of Catalysts

Table 2. Hydrogenation Performance of Catalysts

Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims without departing from the invention.

Claims

A catalyst for producing ethylene glycol by hydrogenating an oxalate, comprising of:

(a) an active component in the form of nanoparticles comprising copper or a cooper oxide;

(b) an auxiliary agent in the form of nanoparticles comprising an element selected from the group consisting of nickel, cobalt, manganese, zinc, aluminum, zirconium, cerium, lanthanum, molybdenum, barium, vanadium, titanium, iron, yttrium, niobium, tungsten, tin, bismuth, strontium, boron and phosphorus; and

(c) a carrier in the form of hollow silica microspheres having microsphere surfaces, wherein the nanoparticles of the active component and the nanoparticles of the auxiliary dispersed on the microsphere surfaces.
The catalyst of claim 1, wherein the catalyst has a specific surface area of 100-1200 m ²/g.
The catalyst of claim 1, wherein the catalyst comprises the active agent at a concentration of 5-35 wt%.
The catalyst of claim 1, wherein the catalyst comprises the auxiliary agent at a concentration of 0.01-20 wt%.
The catalyst of claim 1, wherein the oxalate is dimethyl oxalate, diethyl oxalate, or a combination thereof.
A process for preparing the catalyst of claim 1, comprising:

(a) adding a copper solution and an element precursor/dispersant solution to form Solution III;

(b) adding cetyltrimethylammonium bromide (CTAB) , a templating agent and then ammonia water to a carrier precursor solution to form Mixture IV;

(c) adding Solution III to Mixture IV in the presence of nitrogen gas and heat to form a reaction product;

(d) dehydrating the reaction product to generate precipitates;

(e) washing and drying the precipitates to form a cured product; and

(f) calcining the cured product, whereby a catalyst having a hollow silica microsphere structure is obtained.
The process of claim 6, wherein the element precursor/dispersant solution has a pH of 1.0-7.0.
The process of claim 6, further comprising adding an element precursor to deionized water to form an element precursor solution, and adding a dispersant to the element precursor solution to form the element precursor/dispersant solution.
The process of claim 8, wherein the element is selected from the group consisting of nickel, cobalt, manganese, zinc, aluminum, zirconium, cerium, lanthanum, molybdenum, barium, vanadium, titanium, iron, yttrium, niobium, tungsten, tin, bismuth, strontium, boron and phosphorus.
The process of claim 8, wherein the dispersant is selected from the group consisting of citric acid, ammonium citrate, acetic acid, ammonium acetate, malonic acid, succinic acid, tartaric acid, glucose and oxalic acid.
The process of claim 6, further comprising dissolving a soluble copper salt in deionized water to form the copper solution, wherein the soluble copper salt is selected from the group consisting of copper nitrate, copper acetate, copper chloride and copper oxalate.
The process of claim 6, further comprising dissolving a carrier precursor in a mixture of anhydrous ethanol and deionized water to form the carrier precursor solution.
The process of claim 12, wherein the carrier precursor is selected from the group consisting of silica sol, methyl orthosilicate, tetraethyl orthosilicate, propyl orthosilicate and butyl orthosilicate.
The process of claim 6, wherein the templating agent is a hard templating agent maintained by a covalent bond.
The process of claim 14, wherein the hard templating agent is selected from the group consisting of polystyrene, phenolic resin, porous silicon, activated carbon, polymethyl methacrylate, and bisphenol A epoxy resin.
A method for producing ethylene glycol, comprising hydrogenating an oxalate to ethylene glycol in the presence of hydrogen and the catalyst of claim 1.
The method of claim 16, wherein the oxalate is converted at an average rate of at least 99.0%for at least 2,000 hour. 18. The method of claim 16, wherein the catalyst has an average selectivity of at least 95.0%for ethylene glycol for at least 2,000 hour.
The method of claim 16, wherein the ethylene glycol is produced at an average yield of at least 600.0 mg/g cat/h for least 2,000 hours.
The method of claim 16, wherein the oxalate is dimethyl oxalate.