Supported noble metal alloy particle catalyst and application thereof in preparation of methyl glycolate

Abstract

The invention discloses a supported noble metal alloy particle catalyst and application thereof in preparation of methyl glycolate, and belongs to the technical field of catalysis. According to the supported noble metal alloy particle catalyst, gold serves as a main active component, palladium, platinum, nickel, ruthenium, copper, iridium and rhodium are introduced to serve as auxiliaries to modulate the activity of the nanogold catalyst, the loading amount of the gold in the catalyst is 0.2-10 wt%, the molar ratio of the gold to the auxiliaries is 1: 10-10: 1, the catalyst is prepared through a precipitation method or a colloid method, and the supported noble metal alloy particle catalyst is obtained. And adding the prepared catalyst into a reaction kettle, adding a mixed solution of an alkaline substance, ethylene glycol and methanol, and carrying out oxidative esterification reaction in an oxygen-containing atmosphere at the reaction pressure of 0.5-5 MPa and the reaction temperature of 70-200 DEG C to prepare methyl glycolate. According to the catalyst disclosed by the invention, the use amount of gold is greatly reduced to 50% or above by introducing the aid, and the cost of the catalyst is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysis, and in particular relates to a highly efficient and relatively cheap supported noble metal alloy particle catalyst and application thereof in the preparation of methyl glycolate. Background Art

[0002] Methyl glycolate is a very important intermediate in drug synthesis and organic synthesis. It can undergo a series of chemical reactions such as amination, hydrolysis, hydrogenation, and oxidative dehydrogenation. Methyl glycolate is also an excellent solvent for cellulose, resin, and rubber. Since the 1960s, many developed countries have begun to develop processes suitable for large-scale production of methyl glycolate. These processes include: addition of formaldehyde to hydrocyanic acid, addition of methylal to formaldehyde free radicals, carbonylation and esterification of formaldehyde, and coupling reaction of methyl formate and formaldehyde. These processes have been gradually eliminated due to the high price of raw materials, serious corrosion in the production process, and difficulty in separating products.

[0003] In recent years, people have used ethylene glycol and methanol as starting materials to synthesize methyl glycolate through a one-step oxidative esterification reaction. The raw materials in this process are cheap and widely available, the reaction is completed in a one-step method, the process is simple, and it is green and environmentally friendly. In particular, the separation and purification process of the product is simple, the product purity is high, and the cost is low.

[0004] Invention patent CN1720218A uses a deposition precipitation method to disperse nano-sized activated gold on metal oxides for one-step oxidative esterification of ethylene glycol to prepare glycolic acid methyl ester, inhibiting or preventing side reactions generated by α-hydroxycarboxylic acid esters. Nano Au catalysts have good activity in the oxidative esterification of ethylene glycol to prepare glycolic acid methyl ester, but their gold loading is high, resulting in high catalyst costs. Therefore, reducing the amount of gold used is currently the top priority for reducing catalyst costs. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide an efficient and relatively inexpensive supported precious metal alloy particle catalyst and its use in the preparation of methyl glycolate. The present invention prepares an oxide-supported gold catalyst by loading gold nanoparticles onto an oxide carrier through a colloid method or a deposition precipitation method, and modulates the activity of the nano-gold catalyst by introducing one of the elements such as palladium, platinum, nickel, ruthenium, copper, iridium, rhodium, etc., so as to achieve the same catalytic effect as a single gold nanocatalyst, further reduce the gold loading in the catalyst, and reduce the catalyst cost.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a supported noble metal alloy particle catalyst, which has the general formula of Au-M / X, wherein Au is the main active component gold, M is an auxiliary agent, which is one or more of palladium, platinum, nickel, ruthenium, copper, iridium and rhodium, and X is a carrier, which is a metal oxide, a non-metal oxide or a molecular sieve.

[0008] Based on the above technical solution, further, the gold loading in the catalyst is 0.2-10wt%, preferably 0.5-1wt%, and the molar ratio of gold to the auxiliary agent is 1:10-10:1, preferably 1:5-5:1.

[0009] Based on the above technical scheme, further, the carrier is one or a mixture of two or more of Al2O3, MgO, SiO2, CaO, ZnO, CeO2, CuO, MnO2, Co3O4, Nb2O5, SnO2, MoO3, TS-1 molecular sieve, SAPO molecular sieve, ZSM-5 molecular sieve, Beta molecular sieve, mordenite, X-type zeolite, and Y-type zeolite.

[0010] Based on the above technical solution, further, the catalyst is prepared by a precipitation method or a colloid method:

[0011] The specific process of the precipitation method is: the solution of gold salt and auxiliary salt is dissolved in water and then mixed with the carrier, and then a precipitant is added, and the pH is adjusted to 8-13. After the obtained precipitate is dried, it is roasted in an air atmosphere and then reduced in a hydrogen atmosphere to obtain a supported catalyst;

[0012] The specific process of the colloid method is: disperse the solution of gold salt and auxiliary salt and the carrier in an aqueous solution, add excess protective agent and reducing agent, stir for 1-5 hours, filter, wash with water, dry, calcine in an air atmosphere, and then reduce in a hydrogen atmosphere to obtain a supported catalyst.

[0013] Based on the above technical solution, further, the gold salt is one of the sulfate, nitrate, oxalate, chloride, acetate and phosphate of gold; the auxiliary agent salt is one of the sulfate, nitrate, oxalate, chloride, acetate and phosphate of the auxiliary agent.

[0014] Based on the above technical solution, further, the precipitant described in the precipitation method is one of sodium carbonate, sodium bicarbonate, sodium hydroxide and potassium hydroxide.

[0015] Based on the above technical solution, further, the calcination temperature in the precipitation method is 300-800°C, preferably 400-600°C, and the calcination time is 1-24h, preferably 2-10h; the reduction temperature is 200-400°C, preferably 250-350°C, and the reduction time is 1-24h, preferably 2-10h.

[0016] Based on the above technical scheme, further, the protective agent described in the colloid method is one of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP), the molar ratio of the protective agent to gold is 100:1 to 5:1, and the reducing agent is one of sodium borohydride, lithium borohydride, and potassium borohydride.

[0017] Based on the above technical solution, further, in the colloid method, the calcination temperature is 200-500°C, preferably 300-500°C, and the calcination time is 1-24h, preferably 2-10h; the reduction temperature is 200-400°C, preferably 250-350°C, and the reduction time is 1-24h, preferably 2-10h.

[0018] The present invention also provides a method for preparing methyl glycolate, wherein the above catalyst is added into a reaction kettle, and a mixed solution of alkaline substance, ethylene glycol and methanol is added, and an oxidative esterification reaction is carried out in an oxygen-containing atmosphere, the reaction pressure is 0.5-5MPa, and the reaction temperature is 70-200°C to obtain methyl glycolate.

[0019] Based on the above technical solution, further, the reaction pressure of the oxidative esterification is 1-3 MPa, the reaction temperature is 80-120° C., and the reaction time is 0.5-24 h.

[0020] Based on the above technical solution, further, the alkaline substance is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and the concentration of the alkaline substance is 0.0001-0.1 g / mL.

[0021] Based on the above technical solution, further, the molar ratio of methanol to ethylene glycol is 0.1-50:1, preferably 5-50:1; the amount of catalyst added is 0.1-20wt% of the total amount of methanol and ethylene glycol, preferably 1-10wt%.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention loads gold nanoparticles onto an oxide carrier by a colloid method or a deposition precipitation method to prepare an oxide-loaded gold catalyst, and modulates the activity of the nano-gold catalyst by introducing one or more elements such as palladium, platinum, nickel, ruthenium, copper, iridium, rhodium, etc., thereby further reducing the gold loading in the catalyst and reducing the catalyst cost. The catalyst prepared by the method has higher activity in the oxidative esterification reaction of ethylene glycol than a single gold nanocatalyst, and can be reduced to about half of the original gold loading under the condition of the same yield, thereby greatly reducing the catalyst cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments are briefly introduced below.

[0025] Figure 1 This is the EDX analysis chart of the 0.5% Au 0.1% Pd / Al 2 O 3 catalyst prepared in Example 1. DETAILED DESCRIPTION

[0026] The present invention is described in detail below through specific examples, but these examples do not limit the contents of the present invention.

[0027] The reaction products in the examples were analyzed on-line by gas chromatography.

[0028] The conversion rate of ethylene glycol is calculated as follows:

[0029] Conv(ethylene glycol)%=[1-(amount of unreacted ethylene glycol / amount of supplied ethylene glycol)]×100%

[0030] The selectivity of methyl glycolate is calculated as follows:

[0031] S (methyl glycolate)% = [the amount of substance of methyl glycolate produced / (the amount of substance of ethylene glycol supplied-the amount of substance of unreacted ethylene glycol)]×100%.

[0032] Comparative Example 1

[0033] Take 0.1 ml of 1 mol / L chloroauric acid aqueous solution, dissolve it in 150 mL of water, add alumina carrier, disperse evenly, adjust the solution pH to 8 with sodium carbonate and maintain for 2 hours, filter, wash and dry, and calcine at 350°C for 2 hours to obtain the catalyst 1% Au / Al2O3.

[0034] Comparative Example 2

[0035] Referring to the method of Comparative Example 1, a catalyst 0.5% Au / Al2O3 was prepared.

[0036] Comparative Example 3

[0037] Referring to the method of Comparative Example 1, the aqueous chloroauric acid solution was replaced with a chloropalladic acid solution to prepare a catalyst 1% Pd / Al2O3.

[0038] Reaction evaluation of the catalyst of Comparative Examples 1-3 The selective oxidation reaction of ethylene glycol was carried out in a high-pressure reactor. 0.5 g of catalyst, 0.01 g of sodium carbonate, 10 mL of a mixed solution of ethylene glycol and methanol, the molar ratio of methanol to ethylene glycol was 10:1, the air pressure was filled to 3 MPa, the reaction temperature was 80 ° C, the reaction time was 2 h, and the ethylene glycol conversion rate and methyl glycolate selectivity results are shown in Table 1.

[0039] Table 1. Catalytic activity of the catalysts of Comparative Examples 1-3 in the oxidative esterification of ethylene glycol to methyl glycolate

[0040] Comparative Example catalyst Ethylene glycol conversion % Methyl glycolate selectivity % 1 <![CDATA[1%Au / Al2O3]]> 51 92 2 <![CDATA[0.5%Au / Al2O3]]> 26 95 3 <![CDATA[1%Pd / Al2O3]]> 19 40

[0041] Example 1

[0042] Catalyst preparation: Take 0.05mL 1mol / L chloroauric acid aqueous solution and 0.01mL 1mol / L chloropalladic acid solution, with a molar ratio of gold to palladium of 5:1, dissolve in 150mL water, add alumina carrier, and disperse evenly. Use sodium carbonate to adjust the solution pH to 8 and keep it for 2h, filter, wash and dry, calcine at 500℃ for 2h, and then reduce in hydrogen at 300℃ for 2h to obtain the catalyst 0.5%Au0.1%Pd / Al2O3.

[0043] Figure 1 This is the EDX image of the catalyst prepared in Example 1. It can be clearly observed from the image that the nanoparticles on the surface of the catalyst have two components, gold and palladium, and the two components are evenly distributed, indicating that gold and palladium form an alloy.

[0044] Example 2

[0045] Referring to the method of Example 1, a catalyst 0.5% Au 0.1% Pt / Al2O3 was prepared.

[0046] Example 3

[0047] Referring to the method of Example 1, a catalyst 0.5% Au 0.1% Rh / Al2O3 was prepared.

[0048] Example 4

[0049] Referring to the method of Example 1, a catalyst 0.5% Au 0.1% Ru / Al2O3 was prepared.

[0050] Example 5

[0051] Referring to the method of Example 1, a catalyst 0.5% Au 0.05% Ir / Al2O3 was prepared.

[0052] Reaction evaluation of the catalyst of Examples 1-5 The selective oxidation reaction of ethylene glycol was carried out in a high-pressure reactor, taking 0.5 g of catalyst, 0.01 g of sodium carbonate, 10 mL of a mixed solution of ethylene glycol in methanol, the molar ratio of methanol to ethylene glycol being 10:1, the air pressure was filled to 3 MPa, the reaction temperature was 80°C, and the reaction time was 2 h. The results of ethylene glycol conversion and methyl glycolate selectivity are shown in Table 2.

[0053] Table 2. Catalytic activity of the catalysts of Examples 1-5 in the oxidative esterification of ethylene glycol to methyl glycolate

[0054] Example catalyst Ethylene glycol conversion % Methyl glycolate selectivity % 1 <![CDATA[0.5%Au0.1%Pd / Al2O3]]> 66 92 2 <![CDATA[0.5%Au0.1%Pt / Al2O3]]> 47 93 3 <![CDATA[0.5%Au0.1%Rh / Al2O3]]> 50 91 4 <![CDATA[0.5%Au0.1%Ru / Al2O3]]> 45 88 5 <![CDATA[0.5%Au0.05%Ir / Al2O3]]> 50 91

[0055] Example 6

[0056] Catalyst preparation: The gold-based catalyst was prepared by the colloid method. 0.05 mL of 1 mol / L chloroauric acid aqueous solution and 0.01 mL of 1 mol / L chloropalladic acid solution were dissolved in 150 mL of water, with a molar ratio of gold to palladium of 5:1. The mixture was added to an alumina carrier and dispersed evenly. A certain amount of PVA (molecular weight of 20,000) was added to ensure that the molar ratio of PVA to gold was 10:1. An excess of sodium borohydride was then added. After stirring for 1 h, the mixture was filtered and washed with a large amount of water. After drying at 80 °C, the mixture was calcined at 350 °C in an air atmosphere for 2 h, and then reduced in hydrogen at 300 °C for 2 h to obtain the catalyst 0.5% Au0.1% Pd / Al2O3-I.

[0057] Example 7

[0058] Referring to the method of Example 6, a catalyst 0.5% Au 0.1% Pt / Al2O3-I was prepared.

[0059] Example 8

[0060] Referring to the method of Example 6, a catalyst 0.5% Au0.1% Rh / Al2O3-I was prepared.

[0061] Example 9

[0062] Referring to the method of Example 6, a catalyst 0.5% Au 0.1% Ru / Al2O3-I was prepared.

[0063] Example 10

[0064] Referring to the method of Example 6, a catalyst 0.5% Au0.05% Ir / Al2O3-I was prepared.

[0065] Catalyst reaction evaluation of Examples 6-10 The selective oxidation reaction of ethylene glycol was carried out in a high-pressure reactor, with 0.5 g of catalyst, 0.01 g of sodium carbonate, 10 mL of a mixed solution of ethylene glycol in methanol, a molar ratio of methanol to ethylene glycol of 10:1, and air pressure of 3 MPa, a reaction temperature of 80°C, and a reaction time of 2 h. The results of ethylene glycol conversion and methyl glycolate selectivity are shown in Table 3.

[0066] Table 3. Catalytic activity of gold-based catalysts prepared by colloidal method in the oxidative esterification of ethylene glycol to methyl glycolate

[0067] Example catalyst Ethylene glycol conversion % Methyl glycolate selectivity % 6 <![CDATA[0.5%Au0.1%Pd / Al2O3-I]]> 63 94 7 <![CDATA[0.5%Au0.1%Pt / Al2O3-I]]> 55 90 8 <![CDATA[0.5%Au0.1%Rh / Al2O3-I]]> 43 88 9 <![CDATA[0.5%Au0.1%Ru / Al2O3-I]]> 53 90 10 <![CDATA[0.5%Au0.05%Ir / Al2O3-I]]> 37 89

[0068] Embodiment 11

[0069] Referring to the method of Example 1, a catalyst 0.1% Au 0.5% Pt / SiO 2 was prepared using SiO 2 as a carrier.

[0070] Example 12

[0071] Referring to the method of Example 1, a catalyst 0.1% Au 0.5% Rh / ZnO was prepared using ZnO as a carrier.

[0072] Embodiment 13

[0073] Referring to the method of Example 1, the chloropalladium acid solution was replaced with a chloroplatinic acid solution to prepare a catalyst 0.1% Au 0.5% Ru / MgO.

[0074] Embodiment 14

[0075] Referring to the method of Example 1, a catalyst 0.1% Au 0.5% Ir / ZSM molecular sieve was prepared using ZSM-5 molecular sieve (Louwen, Jaap N., et al. "Understanding the activation of ZSM-5 by phosphorus: Localizing phosphate groups in the pores of phosphate-stabilized ZSM-5." American Chemical Society (ACS) 21 (2020).) as a carrier.

[0076] Embodiment 15

[0077] Referring to the method of Example 1, a catalyst 0.1% Au 0.5% Pt / TS-1 molecular sieve was prepared using TS-1 molecular sieve (Cheneviere, Yohan, et al. "Synthesis and catalytic properties of TS-1 with mesoporous / microporous hierarchical structures obtained in the presence of amphiphilic organosilanes." Journal of Catalysis 269.1 (2010): 161-168.) as a carrier.

[0078] Catalyst reaction evaluation of Examples 11-15 The selective oxidation reaction of ethylene glycol was carried out in a high-pressure reactor, with 0.5 g of catalyst, 0.01 g of sodium carbonate, 10 mL of a mixed solution of ethylene glycol in methanol, a molar ratio of methanol to ethylene glycol of 10:1, and air pressure of 5 MPa, a reaction temperature of 100°C, and a reaction time of 5 h. The results of ethylene glycol conversion and methyl glycolate selectivity are shown in Table 4.

[0079] Table 4. Catalytic activity of catalysts supported by different carriers in the oxidative esterification of ethylene glycol to methyl glycolate

[0080] Example catalyst Ethylene glycol conversion % Methyl glycolate selectivity % 11 <![CDATA[0.5%Au0.1%Pt / SiO2]]> 55 87 12 0.5%Au0.1%Rh / ZnO 61 90 13 0.5%Au0.1%Ru / MgO 66 93 14 0.5%Au0.1%Ir / ZSM 49 86 15 0.5%Au0.1%Pt / TS-1 50 85

Claims

1. A supported noble metal alloy particle catalyst, characterized in that: The general formula is: Au-M / X, wherein Au is the main active component gold, M is an auxiliary agent, which is one or more of palladium, platinum, nickel, ruthenium, copper, iridium and rhodium, X is a carrier, which is a metal oxide, a non-metallic oxide or a molecular sieve, the gold loading amount in the catalyst is 0.2-10wt%, preferably 0.5-1wt%, and the molar ratio of gold to the auxiliary agent is 1:10-10:1, preferably 1:5-5:

1.

2. The supported noble metal alloy particle catalyst according to claim 1, characterized in that: The carrier is one or a mixture of two or more of Al2O3, MgO, SiO2, CaO, ZnO, CeO2, CuO, MnO2, Co3O4, Nb2O5, SnO2, MoO3, TS-1 molecular sieve, SAPO molecular sieve, ZSM-5 molecular sieve, Beta molecular sieve, mordenite, X-type zeolite, and Y-type zeolite.

3. The supported noble metal alloy particle catalyst according to claim 1, characterized in that: The catalyst is prepared by a precipitation method or a colloid method: The specific process of the precipitation method is: the solution of gold salt and auxiliary salt is dissolved in water and then mixed with the carrier, and then a precipitant is added, and the pH is adjusted to 8-13. After the obtained precipitate is dried, it is roasted in an air atmosphere and then reduced in a hydrogen atmosphere to obtain a supported catalyst; The specific process of the colloid method is: disperse the solution of gold salt and auxiliary salt and the carrier in an aqueous solution, add excess protective agent and reducing agent, stir for 1-5 hours, filter, wash with water, dry, calcine in an air atmosphere, and then reduce in a hydrogen atmosphere to obtain a supported catalyst.

4. The supported noble metal alloy particle catalyst according to claim 3, characterized in that: The gold salt is one of the sulfate, nitrate, oxalate, chloride, acetate and phosphate of gold; the auxiliary salt is one of the sulfate, nitrate, oxalate, chloride, acetate and phosphate of the auxiliary.

5. The supported noble metal alloy particle catalyst according to claim 3, characterized in that: The precipitant described in the precipitation method is one of sodium carbonate, sodium bicarbonate, sodium hydroxide and potassium hydroxide; the roasting temperature in the precipitation method is 300-800°C, preferably 400-600°C, and the roasting time is 1-24h, preferably 2-10h; the reduction temperature is 200-400°C, preferably 250-350°C, and the reduction time is 1-24h, preferably 2-10h.

6. The supported noble metal alloy particle catalyst according to claim 3, characterized in that: The protective agent described in the colloid method is one of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP), the molar ratio of the protective agent to gold is 100:1 to 5:1, and the reducing agent is one of sodium borohydride, lithium borohydride, and potassium borohydride; The calcination temperature in the colloid method is 200-500°C, preferably 300-500°C, and the calcination time is 1-24h, preferably 2-10h; the reduction temperature is 200-400°C, preferably 250-350°C, and the reduction time is 1-24h, preferably 2-10h.

7. A method for preparing methyl glycolate, characterized in that: The catalyst according to any one of claims 1 to 6 is added into a reaction kettle, and a mixed solution of alkaline substances, ethylene glycol and methanol is added, and an oxidative esterification reaction is carried out in an oxygen-containing atmosphere at a reaction pressure of 0.5-5 MPa and a reaction temperature of 70-200° C. to obtain methyl glycolate.

8. The method according to claim 7, characterized in that The reaction pressure of oxidative esterification is 1-3 MPa, the reaction temperature is 80-120°C, and the reaction time is 0.5-24h.

9. The method according to claim 7, characterized in that: The alkaline substance is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and the concentration of the alkaline substance is 0.0001-0.1 g / mL.

10. The method according to claim 7, characterized in that The molar ratio of methanol to ethylene glycol is 0.1-50:1, preferably 5-50:1; the amount of catalyst added is 0.1-20wt% of the total amount of methanol and ethylene glycol, preferably 1-10wt%.

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