A supported hydrogenation catalyst and its preparation method and application

Abstract

The present invention provides a method for preparing a supported hydrogenation catalyst, comprising the following steps: S1) preparing a metal salt solution A, wherein the solution A contains silver ions and / or palladium ions; preparing a carrier solution B; S2) mixing the metal salt solution A, the carrier solution B and the precipitant solution to obtain a catalyst precursor slurry; S3) evaporating the catalyst precursor slurry by jet instantaneous pyrolysis; S4) subjecting the evaporated material to hot air microspheroidization to obtain a supported hydrogenation catalyst. The present invention introduces an instantaneous pyrolysis method to obtain a catalyst with highly dispersible active components, which effectively improves the low-temperature high activity of the catalyst on the basis of higher selectivity, and the conversion rate of dimethyl oxalate at a lower reaction temperature is greater than 99%, showing excellent catalytic performance and stability. The present invention effectively improves the utilization rate of active components and reduces production costs by improving the catalyst preparation process, which is conducive to the industrialization and promotion of catalysts.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a supported hydrogenation catalyst and a preparation method and application thereof. Background Art

[0002] Methyl glycolate (HOCH 2 COOCH 3 MG) has the chemical properties of both alcohol and ester because of its molecular structure containing α-H, hydroxyl and ester groups. Methyl glycolate can be synthesized into ethylene glycol and ethanol by catalytic hydrogenation, can be hydrolyzed to produce glycolic acid, can be oxidized to produce methyl glyoxylate, can be carbonylated to produce dimethyl malonate, and can be aminolyzed to produce glycine. As an important intermediate for drug synthesis and organic synthesis, methyl glycolate is widely used in many fields such as chemical industry, feed, pesticide, medicine, dyes and fragrances.

[0003] With the large-scale industrial application of coal-to-syngas technology for ethylene glycol in my country, researchers have further developed coal-to-methyl glycolate technology; by further directly polymerizing MG (or hydrolyzing and crystallizing MG to obtain glycolic acid (GA) and then polymerizing it), it is used to prepare biodegradable material polyglycolic acid (PGA). Polyglycolic acid (PGA) is a biodegradable plastic with good market prospects, with excellent degradation performance, biocompatibility and gas-liquid barrier properties. It has great demand space and market potential in countries and regions where plastic restrictions are implemented.

[0004] At present, the production method of methyl glycolate in industry mainly adopts the chloroacetic acid method. First, chloroacetic acid and sodium hydroxide are mixed to undergo a hydrolysis reaction, and then the generated sodium chloride is removed to obtain crude glycolate. Methanol is added under the action of a catalyst to obtain methyl glycolate through an esterification reaction. This method has a long production process, high energy consumption, serious pollution in the production process, and difficult wastewater treatment. The current technology of preparing methyl glycolate from coal through synthesis gas and dimethyl oxalate hydrogenation is more economical and more environmentally friendly than the traditional chloroacetic acid method. With the large-scale construction and commissioning of domestic dimethyl oxalate industrial equipment, the production cost of this method will be greatly reduced, and the market development prospects are optimistic.

[0005] At present, the synthesis methods of catalysts for the gas-phase hydrogenation of dimethyl oxalate to methyl glycolate mainly include conventional preparation methods such as ammonia evaporation, sedimentation precipitation and impregnation. However, the traditional catalyst preparation methods have the problems of poor dispersion of active components and uneven catalyst color, resulting in low utilization of active components, high production costs, and easy sintering leading to poor stability, which is not conducive to the industrial production of catalysts. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a supported hydrogenation catalyst and a preparation method and application thereof, wherein the prepared catalyst active component has high dispersibility.

[0007] To achieve the above object, the present invention provides a method for preparing a supported hydrogenation catalyst, comprising the following steps:

[0008] S1) preparing a metal salt solution A, wherein the solution A contains silver ions and / or palladium ions;

[0009] Prepare carrier solution B;

[0010] S2) mixing the metal salt solution A, the carrier solution B and the precipitant solution to obtain a catalyst precursor slurry;

[0011] S3) evaporating the catalyst precursor slurry by jet instantaneous pyrolysis;

[0012] S4) subjecting the evaporated material to hot air microspheroidization treatment to obtain a supported hydrogenation catalyst.

[0013] Optionally, in the metal salt solution A, the total concentration of silver ions and / or palladium ions is 0.01 to 5 mol / L, and more preferably 0.05 to 1 mol / L.

[0014] When the system contains both silver ions and palladium ions, the molar ratio of silver ions to palladium ions is preferably 5 to 50:1, more preferably 10 to 45:1.

[0015] The compound providing the silver ions may be selected from one or more water-soluble silver-containing compounds such as silver nitrate and silver acetate.

[0016] The compound providing the palladium ions can be selected from one or more water-soluble palladium-containing compounds such as palladium nitrate, palladium chloride or palladium acetate.

[0017] Optionally, the solvent of the metal salt solution A is water.

[0018] Optionally, the metal salt solution A further contains an auxiliary agent.

[0019] The auxiliary agent is preferably one or more of Au ions, Cu ions, In ions, Ce ions, Zr ions, B ions, Mg ions, Mo ions, Ru ions, Rh ions, Fe ions, B ions, Ni ions and Mn ions.

[0020] The concentration of the auxiliary agent in the metal salt solution A is preferably 0.01 to 2 mol / L.

[0021] The auxiliary agent may be provided by a water-soluble compound containing corresponding elements, for example, In may be selected from indium nitrate, Ni may be selected from nickel nitrate, and Mo may be selected from ammonium molybdate.

[0022] Optionally, the pH value of the metal salt solution A can be adjusted to 3-6 by using an acidic substance or an alkaline substance.

[0023] The acidic substance or alkaline substance can be a conventional acidic substance or alkaline substance in the art, for example, the acidic substance can be selected from nitric acid, sulfuric acid, acetic acid or hydrochloric acid, and the alkaline substance can be selected from sodium carbonate, sodium hydroxide, ammonium carbonate, ammonium bicarbonate, sodium bicarbonate or ammonia solution.

[0024] Optionally, the carrier solution B contains one or more of silicon ions, aluminum ions, magnesium ions, zirconium ions, zinc ions, molecular sieves, and white carbon black.

[0025] Optionally, the carrier solution B is an aqueous solution.

[0026] The metal salt solution A, the carrier solution B and the precipitant solution are then mixed.

[0027] Optionally, the volume ratio of the metal salt solution A to the carrier solution B is 1:1-20.

[0028] Optionally, the precipitant is selected from one or more of sodium carbonate, sodium hydroxide, ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonia water or urea.

[0029] Optionally, the molar content of the precipitant is 1 to 25 times the molar content of the active component. Optionally, the solid content concentration of the obtained catalyst precursor slurry is 1% to 30%.

[0030] Then the catalyst precursor slurry is evaporated by jet flash pyrolysis.

[0031] Optionally, the air inlet temperature of the jet instantaneous pyrolysis method is 80-250° C., more preferably 100-200° C. In some specific embodiments of the present invention, the air inlet temperature is 100° C., 110° C., 120° C., 150° C., 180° C., 200° C., or an interval with any of the above values ​​as the upper or lower limit.

[0032] Optionally, the injection pressure of the injection instantaneous pyrolysis method is 0.1 to 60 bar, more preferably 0.5 to 20 bar. In some specific embodiments of the present invention, the injection pressure is 0.5 bar, 1 bar, 2 bar, 5 bar, 10 bar, 15 bar, or an interval with any of the above values ​​as the upper or lower limit.

[0033] Optionally, a device with a spray or centrifugal drying function is used for jet instantaneous pyrolysis. The catalyst precursor slurry is pumped to the atomizer. The atomizer evenly atomizes the liquid into ultra-micron droplets and enters the tower. The air enters the heating system, is heated to the temperature required for the process, and pyrolyzes into the required material after contacting the droplets.

[0034] After the jet instant pyrolysis method, the material is subjected to hot air microspheroidization treatment to obtain a supported hydrogenation catalyst.

[0035] Optionally, the temperature of the hot air microspheroidization treatment is 80-150° C., more preferably 90-150° C. In some specific embodiments of the present invention, the temperature is 90° C., 100° C., 110° C., 120° C., 130° C., 140° C., 150° C., or an interval with any of the above values ​​as the upper or lower limit.

[0036] Optionally, the hot air microspheroidization treatment time is 1 to 30 min, more preferably 5 to 15 min. In some specific embodiments of the present invention, the time is 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 min, or an interval with any of the above values ​​as the upper or lower limit.

[0037] Under the control of the temperature and time parameters of the hot air microspheroidization treatment, the particle size of the microspheres after treatment is 0.075-1 mm.

[0038] The hot air microspheroidization treatment described in the present invention is to put the powder material with small particle size obtained by the jet instantaneous pyrolysis method into a high temperature resistant container, and blow the hot air heated by the electric heating wire into it from one side of the beaker. The powder with small particle size collides and adheres to each other in the hot air, and finally the powder is processed into fine particles with larger particle size and higher strength.

[0039] Optionally, the high temperature resistant container is a hard glass container.

[0040] Optionally, the present invention further comprises calcination after the hot air microspheroidization treatment.

[0041] Optionally, the calcination temperature is 300 to 650° C., more preferably 300 to 600° C. The calcination time is 0.5 to 12 hours, more preferably 1 to 6 hours.

[0042] Optionally, when preparing industrial-grade granular catalysts, the hot air microspheroidization treatment further includes dry or wet granulation, calcination and molding.

[0043] The present invention provides a supported hydrogenation catalyst, which is prepared by the above preparation method.

[0044] Optionally, in the catalyst, silver and / or palladium are used as active components, and their total content is 0.01% to 18% of the weight of the catalyst.

[0045] The additive is an oxide of one or more of the elements Au, Cu, In, Ce, Zr, B, Mg, Mo, Ru, Rh, Fe, B, Ni and Mn.

[0046] The content of the auxiliary agent accounts for 0.01% to 5% of the weight of the catalyst.

[0047] The carrier is one or more of silicon, aluminum, magnesium, zirconium, zinc oxide, molecular sieve, and white carbon black; preferably silicon oxide or white carbon black.

[0048] The mass content of the above-mentioned active components and auxiliary agents is based on the total weight of the catalyst (including active components, auxiliary agents and carriers). Therefore, the total mass content of the active components, auxiliary agents and carriers meets 100%. After deducting the total mass content of the active components and auxiliary agents, the remainder is the mass content of the carrier.

[0049] The catalyst is prepared by an instantaneous pyrolysis method.

[0050] The present invention provides a supported hydrogenation catalyst prepared by the preparation method or application of the supported hydrogenation catalyst as a catalyst for the gas-phase hydrogenation of dimethyl oxalate to produce methyl glycolate.

[0051] The invention provides a gas phase hydrogenation reaction for preparing methyl glycolate from dimethyl oxalate, and adopts the supported hydrogenation catalyst prepared by the preparation method or the supported hydrogenation catalyst as a catalyst.

[0052] Compared with the prior art, the present invention provides a method for preparing a supported hydrogenation catalyst, comprising the following steps: S1) preparing a metal salt solution A, wherein the solution A contains silver ions and / or palladium ions; preparing a carrier solution B; S2) mixing the metal salt solution A, the carrier solution B and a precipitant solution to obtain a catalyst precursor slurry; S3) evaporating the catalyst precursor slurry by a jet instantaneous pyrolysis method; and S4) subjecting the evaporated material to a hot air microspheroidization treatment to obtain a supported hydrogenation catalyst.

[0053] The present invention creatively introduces a transient pyrolysis method to obtain a catalyst with highly dispersed active components, which effectively improves the low-temperature high activity of the catalyst on the basis of high selectivity. The conversion rate of dimethyl oxalate of the catalyst at a relatively low reaction temperature is greater than 99%, showing excellent catalytic performance and stability. In addition, the present invention effectively improves the utilization rate of the active components and reduces the production cost by improving the catalyst preparation process, which is conducive to the industrialization and promotion of the catalyst. DETAILED DESCRIPTION

[0054] In order to further illustrate the present invention, the supported hydrogenation catalyst provided by the present invention and its preparation method and application are described in detail below in conjunction with examples.

[0055] Example 1

[0056] 4.7g silver nitrate, 0.2g palladium nitrate and 0.4g cerium nitrate were placed in a beaker, 100g distilled water was added to completely dissolve them, and then concentrated nitric acid was slowly dripped into the beaker with a dropper to adjust the pH to 4, which was recorded as solution A; 47g white carbon black was weighed, 1000g distilled water was added and stirred evenly, which was recorded as solution B; 100g sodium carbonate solution (mass concentration 10%) was added to solution A and solution B, and the obtained catalyst precursor slurry was evaporated by jet instant pyrolysis method, the spray inlet temperature was 100℃, and the spray pressure was 1bar; then the material was subjected to hot air microspheroidization treatment, the hot air temperature was 90℃, the treatment time was 15min, and the particle size of the main particles after treatment was 0.09-0.12mm; calcined at 400℃ for 3 hours to obtain the target product catalyst. The target catalyst has a uniform appearance color.

[0057] Example 2

[0058] 7.9g of silver nitrate and 0.9g of indium nitrate were placed in a beaker, and 100g of distilled water was added to completely dissolve them, which was recorded as solution A; 180g of silica sol was weighed, and 100g of distilled water was added and stirred evenly, which was recorded as solution B; 90g of sodium bicarbonate solution (mass concentration 10%) was added to solution A and solution B, and the mixture was fully stirred and mixed evenly, and the obtained catalyst precursor slurry was evaporated by jet instant pyrolysis method, with the spray inlet temperature of 120°C and the spray pressure of 5bar; then the material was subjected to hot air microspheroidization treatment, with the hot air temperature of 100°C and the treatment time of 13min, and the particle size of the main particles after treatment was 0.08-0.10mm; and the target product catalyst was obtained by roasting at 350°C for 6 hours. The target catalyst has a uniform appearance color.

[0059] Example 3

[0060] 11.8g of silver nitrate was placed in a beaker, 100g of distilled water was added to completely dissolve it, and then concentrated nitric acid was slowly dripped in with a dropper to adjust the pH to 5, which was recorded as solution A; 43g of white carbon black was weighed, 2000g of distilled water was added and stirred evenly, which was recorded as solution B; 150g of sodium carbonate solution (mass concentration 8%) was added to solution A and solution B, and the obtained catalyst precursor slurry was evaporated by jet instant pyrolysis, the centrifugal inlet temperature was 120°C, and the jet pressure was 10bar; then the material was subjected to hot air microspheroidization treatment, the hot air temperature was 130°C, the treatment time was 8min, and the particle size of the main particles after treatment was 0.1-0.3mm; and the target product catalyst was obtained by roasting at 500°C for 4 hours. The target catalyst has a uniform appearance color.

[0061] Example 4

[0062] 1.6g palladium chloride and 2.0g nickel nitrate were placed in a beaker, 100g distilled water was added to completely dissolve them, and then concentrated nitric acid was slowly dripped in with a dropper to adjust the pH to 5, which was recorded as solution A; 49g white carbon black was weighed, 1000g distilled water was added and stirred evenly, which was recorded as solution B; 20g sodium hydroxide solution (mass concentration 15%) was added to solution A and solution B, and the obtained catalyst precursor slurry was evaporated by jet instant pyrolysis method, the centrifugal inlet temperature was 200℃, and the jet pressure was 15bar; then the material was subjected to hot air microspheroidization treatment, the hot air temperature was 150℃, the treatment time was 5min, and the particle size of the main particles after treatment was 0.4-0.7mm; and the target product catalyst was obtained by roasting at 400℃ for 4 hours. The target catalyst has a uniform appearance color.

[0063] Example 5

[0064] 4.7g of silver acetate, 0.6g of palladium nitrate and 0.5g of ammonium molybdate were placed in a beaker, and 100g of distilled water was added to completely dissolve them, which was recorded as solution A; 150g of silica sol was weighed, and 200g of distilled water was added and stirred evenly, which was recorded as solution B; 100g of sodium carbonate solution (mass concentration 10%) was added to solution A and solution B, and the mixture was fully stirred and mixed evenly, and the obtained catalyst precursor slurry was evaporated by jet instant pyrolysis method, with centrifugal inlet temperature of 180°C and jet pressure of 0.5bar; then the material was subjected to hot air microspheroidization treatment, with the hot air temperature of 120°C and the treatment time of 9min, and the particle size of the main particles after treatment was 0.4-0.6mm; and the target product catalyst was obtained by roasting at 600°C for 2 hours. The target catalyst has a uniform appearance color.

[0065] Example 6

[0066] 6.3g silver nitrate, 0.2g palladium nitrate and 0.3g nickel nitrate were placed in a beaker, 100g distilled water was added to completely dissolve them, and then concentrated nitric acid was slowly dripped in with a dropper to adjust the pH to 4, which was recorded as solution A; 46g white carbon black was weighed, 1000g distilled water was added and stirred evenly, which was recorded as solution B; 100g sodium carbonate solution (mass concentration 10%) was added to solution A and solution B, and the obtained catalyst precursor slurry was evaporated by jet instant pyrolysis method, the spray inlet temperature was 100℃, and the spray pressure was 2bar; then the material was subjected to hot air microspheroidization treatment, the hot air temperature was 90℃, the treatment time was 14min, and the particle size of the treated main particles was 0.08-0.15mm; calcined at 400℃ for 4 hours to obtain the target product catalyst. The target catalyst has a uniform appearance color.

[0067] Comparative Example 1

[0068] 6.3g silver nitrate, 0.2g palladium nitrate and 0.3g nickel nitrate were placed in a beaker, 100g distilled water was added to completely dissolve them, and then concentrated nitric acid was slowly dripped into the beaker with a dropper to adjust the pH to 4, which was recorded as solution A; 46g white carbon black was weighed, 1000g distilled water was added and stirred evenly, which was recorded as solution B; 100g sodium carbonate solution (mass concentration 10%) was added to solution A and solution B, and the mixture was fully stirred and mixed evenly. The obtained catalyst precursor slurry was washed and filtered, dried at 120°C for 8 hours, and calcined at 400°C for 4 hours to obtain the target product catalyst. The target catalyst is in block form, with obvious differences in appearance and uneven color.

[0069] Comparative Example 2

[0070] 6.3g silver nitrate, 0.2g palladium nitrate and 0.3g nickel nitrate were placed in a beaker, 100g distilled water was added to completely dissolve them, and then concentrated nitric acid was slowly dripped in with a dropper to adjust the pH to 4, which was recorded as solution A; 46g white carbon black was weighed, 1000g distilled water was added and stirred evenly, which was recorded as solution B; 100g sodium carbonate solution (mass concentration 10%) was added to solution A and solution B, and the obtained catalyst precursor slurry was evaporated by jet instant pyrolysis method, the spray inlet temperature was 280℃, and the spray pressure was 2bar; then the material was subjected to hot air microspheroidization treatment, the hot air temperature was 90℃, the treatment time was 15min, and the particle size of the main particles after treatment was 0.08-0.15mm; calcined at 400℃ for 4 hours to obtain the target product catalyst. The target catalyst has a uniform appearance color.

[0071] Comparative Example 3

[0072] 6.3g silver nitrate, 0.2g palladium nitrate and 0.3g nickel nitrate were placed in a beaker, 100g distilled water was added to completely dissolve them, and then concentrated nitric acid was slowly dripped in with a dropper to adjust the pH to 4, which was recorded as solution A; 46g white carbon black was weighed, 1000g distilled water was added and stirred evenly, which was recorded as solution B; 100g sodium carbonate solution (mass concentration 10%) was added to solution A and solution B and stirred and mixed evenly, and the obtained catalyst precursor slurry was evaporated by jet instant pyrolysis method, the spray inlet temperature was 100℃, and the injection pressure was 2bar; then the powder material was roasted at 400℃ for 4 hours to obtain the target product catalyst. The target catalyst cannot meet the requirements of industrial application because the powder particles are too fine and the fluidity is poor, and the industrial particle catalyst has low strength and is easy to pulverize. Therefore, the catalyst performance comparison experiment was not carried out.

[0073] The catalysts obtained in Examples 1 to 6 and Comparative Examples 1 to 2 were made into particles of 20-40 mesh size, loaded into a tubular reactor, and activated for 4 hours under a hydrogen atmosphere. The reaction results are shown in Table 1 using a methanol solution of dimethyl oxalate as a raw material, a reaction temperature of 190°C, a liquid hourly space velocity of 0.4 h-1, a hydrogen-ester molar ratio of 50:1, and a reaction pressure of 2.5 MPa.

[0074] Table 1

[0075] sample Conversion rate of dimethyl oxalate / % Methyl glycolate selectivity / % Example 1 99.5 93.2 Example 2 100 92.8 Example 3 99.8 94.3 Example 4 99.6 93.8 Example 5 100 91.5 Example 6 99.6 92.6 Comparative Example 1 95.2 86.4 Comparative Example 2 41.5 76.8

[0076] The present invention controls the conditions of evaporation by the jet instantaneous pyrolysis method, the conditions of the hot air microsphere treatment, and the control of the roasting temperature, so that the particle size of the catalyst particles can be controlled within a certain range, the particle size is relatively uniform, the color is uniform, the strength of the catalyst particles is improved, thereby improving the utilization rate of the active components and achieving a better catalytic effect.

[0077] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. Application of a supported hydrogenation catalyst as a catalyst for the gas phase hydrogenation of dimethyl oxalate to methyl glycolate, the preparation method of the supported hydrogenation catalyst comprising the following steps: S1) preparing a metal salt solution A, wherein the solution A contains silver ions and / or palladium ions; The metal salt solution A also contains an auxiliary agent; The auxiliary agent is one or more of Au ions, Cu ions, In ions, Ce ions, Mo ions, Ru ions, Rh ions, Fe ions, Ni ions and Mn ions; Prepare carrier solution B; S2) mixing the metal salt solution A, the carrier solution B and the precipitant solution to obtain a catalyst precursor slurry; S3) evaporating the catalyst precursor slurry by jet instantaneous pyrolysis; the inlet air temperature of the jet instantaneous pyrolysis is 80-250°C; The jet instantaneous pyrolysis method is as follows: the catalyst precursor slurry is pumped to the atomizer, the atomizer evenly atomizes the slurry into ultra-micron droplets, which enter the tower, and the air enters the heating system, is heated to the temperature required by the process, and pyrolyzes into the required material after contacting the droplets; S4) subjecting the evaporated material to hot air microspheroidization treatment to obtain a supported hydrogenation catalyst; the temperature of the hot air microspheroidization treatment is 80-150°C.

2. The use according to claim 1, characterized in that: The total concentration of the silver ions and / or palladium ions is 0.01-5 mol / L.

3. The use according to claim 1, characterized in that: The concentration of the auxiliary agent is 0.01-2 mol / L.

4. The use according to claim 1, characterized in that: The pH value of the metal salt solution A is adjusted to 3-6 using an acidic substance or an alkaline substance.

5. The use according to claim 1, characterized in that: The carrier solution B contains one or more of silicon ions, aluminum ions, magnesium ions, zirconium ions, zinc ions, molecular sieves, and white carbon black.

6. The use according to claim 1, characterized in that: The precipitant is selected from one or more of sodium carbonate, sodium hydroxide, ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonia water or urea.

7. The use according to claim 1, characterized in that: The injection pressure of the injection instantaneous pyrolysis method is 0.1-60 bar.

8. The use according to claim 1, characterized in that: In the catalyst, the content of silver and / or palladium is 0.01% to 18% of the weight of the catalyst.