CN112705247B

CN112705247B - Solid acid catalyst and preparation method and application thereof

Info

Publication number: CN112705247B
Application number: CN201911019389.3A
Authority: CN
Inventors: 王迪; 吕建刚; 刘波; 王振东; 陶伟川; 袁志庆
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Priority date: 2019-10-24
Filing date: 2019-10-24
Publication date: 2022-12-09
Anticipated expiration: 2039-10-24
Also published as: CN112705247A

Abstract

The invention provides a preparation method of a solid acid catalyst, which comprises the following steps: a) Contacting an HZSM-5 molecular sieve with an aqueous solution containing a carbon source, thereby loading the carbon source onto the HZSM-5 molecular sieve; b) Carbonizing the HZSM-5 molecular sieve loaded with the carbon source in an inert atmosphere to prepare a carbonized HZSM-5 molecular sieve; and c) sulfonating the carbonized HZSM-5 molecular sieve to prepare the solid acid catalyst. Firstly, a carbon source is loaded on the HZSM-5 molecular sieve, and then incomplete carbonization treatment and sulfonation treatment are sequentially carried out, so that the stability of the traditional carbon-based solid acid catalyst is improved, and the use of an expensive silanization reagent is avoided.

Description

Solid acid catalyst, preparation method and application thereof

Technical Field

The invention relates to the technical field of chemical industry, in particular to a solid acid catalyst and a preparation method and application thereof.

Background

Methyl glycolate is an important organic chemical raw material, can be widely applied to the fields of chemical industry, polymer materials, pesticides, medicines, spices, feeds, dyes and the like, is an important intermediate for preparing ethylene glycol from coal, and has attracted wide attention in recent years due to the rise of a coal-based route.

The formaldehyde carbonylation is industrially produced by preparing ethylene glycol through methyl glycolate: by using concentrated H ₂ SO ₄ As catalyst, at 150-225 deg.C and P _CO =90MPa, the carbonylation of formaldehyde to glycolic acid, the esterification of glycolic acid to methyl glycolate, the latter to methyl glycolate at 210-215 ℃ P _H2 And (4) catalytically reducing the mixture by using copper chromite to generate glycol under the condition of =3.0 MPa. Because the inorganic acid has strong corrosivity and serious pollution, the production is stopped after the production is put into operation for a long time. In order to solve the problems of strong corrosivity, difficult separation and the like of homogeneous acid catalysts, the development of solid acids which have strong acidity, small corrosivity and easy activation instead of inorganic acids is a new research direction, so solid acids such as ion exchange resins, heteropolyacids, molecular sieves and the like are further developed and used as catalysts for formaldehyde carbonylation reactions.

The carbonylation of formaldehyde is a reaction catalyzed by pure Bronsted acid, and the classical Bronsted acid catalyst has excellent performance of catalyzing the carbonylation of formaldehyde. Hendriksen in Div.Fuel chem.1983, 28. Lee et al in ind ₃ PW ₁₂ O ₄₀ 、H ₃ PMo ₁₂ O ₄₀ When the heteropolyacid was investigated, it was found that the yields of methyl glycolate at 6.8MPa and 23.8MPa were 36% and 81%, respectively, using Amberlyst resin as the catalyst. However, since the resin catalyst is liable to swell and run off in the aqueous system, and formaldehyde is liable to polymerize and adhere to the surface of the solid catalyst, the polymerization phenomenon is more remarkable particularly in the presence of an alkali center, resulting in the deactivation of the catalyst. Therefore, design and construction of the heightEfficient and easily regenerated heterogeneous catalysts are the focus of catalyst research.

In recent years, the development of sulfonic acid type solid acids has become a research focus, and the research idea is to introduce sulfonic acid groups on some carriers (such as mesoporous silicon molecular sieves, mesoporous carbon molecular sieves, amorphous carbon and the like) by various methods to make the carriers have acidity equivalent to that of sulfuric acid. Among them, molecular sieves are most widely used, but because of weak surface acidity, it is necessary to introduce acidic groups such as sulfonate, propylsulfonic acid, etc. thereto by post-treatment. There are two methods used: (1) Post-synthesis grafting method, which comprises reacting silicon hydroxyl on the surface of mesoporous silicon molecular sieve with mercapto (-SH) alkoxy silane to graft-SH into mesoporous molecular sieve, and passing through H ₂ O ₂ oxidizing-SH to sulfonic acid groups; (2) In the sol-gel process of synthesizing mesoporous silicon molecular sieve, alkoxy silane containing mercapto group as reactant and silicon source, surfactant and alkali for synthesizing mesoporous silicon molecular sieve are added simultaneously into the synthetic liquid, and through hydrothermal self-assembly and HNO ₃ Or H ₂ O ₂ The oxidation of-SH to sulfonic acid groups. It has the problems that: the mesoporous silicon molecular sieve has a certain limitation as a sulfonic acid type solid acid due to the inherent problem of small number of surface hydroxyl groups, and expensive mercaptoalkoxysilane is adopted in the preparation process, so that the preparation steps are multiple.

On the other hand, research and development of carbon-based solid acid are also more and more focused, namely, easily polymerizable carbon sources such as sucrose and glucose and concentrated sulfuric acid are heated together to complete carbonization and sulfonation in one step to obtain the sulfonic acid type solid acid catalyst with a macroporous structure. The sulfonic acid type solid acid catalyst prepared by the method has poor stability, and acid groups are easy to fall off in a liquid phase reaction system with higher temperature, so that the activity of the catalyst is reduced or inactivated.

Disclosure of Invention

In view of the problems in the prior art, the present invention aims to provide a solid acid catalyst, a preparation method thereof and an application thereof, wherein a carbon source is loaded on an HZSM-5 molecular sieve, and then incomplete carbonization and sulfonation are sequentially performed, so that the stability of the conventional carbon-based solid acid catalyst is improved, and the use of an expensive silylation reagent is avoided.

One aspect of the present invention provides a method for preparing a solid acid catalyst, comprising:

a) Contacting an HZSM-5 molecular sieve with an aqueous solution containing a carbon source, thereby loading the carbon source onto the HZSM-5 molecular sieve;

b) Carbonizing the HZSM-5 molecular sieve loaded with the carbon source in an inert atmosphere to prepare a carbonized HZSM-5 molecular sieve; and

c) And sulfonating the carbonized HZSM-5 molecular sieve to prepare the solid acid catalyst.

The inventor of the application finds that the carbon-based solid acid carried by the molecular sieve is obtained by introducing the saccharides on the surface of the HZSM-5 molecular sieve, continuously carbonizing and sulfonating the saccharides, and has high stability due to the supporting and fixing effect of the HZSM-5 molecular sieve, and the HZSM-5 itself serving as the solid acid has a catalytic effect on the reaction, so that high catalytic activity and stability are obtained.

According to the present invention, the inert atmosphere may be a nitrogen atmosphere.

In some preferred embodiments of the present invention, the carbon source is selected from at least one of sucrose, glucose and fructose.

In some preferred embodiments of the present invention, the concentration of the carbon source in the aqueous solution containing the carbon source is 10wt% to 30wt%, preferably 15wt% to 25wt%.

In some preferred embodiments of the present invention, the volume of the aqueous solution containing a carbon source is 0.9 to 1.1 times the pore volume of the HZSM-5 molecular sieve.

In some preferred embodiments of the invention, the volume of the aqueous solution containing the carbon source is equal to the pore volume of the HZSM-5 molecular sieve.

According to the invention, the pore volume of the molecular sieve is 0.1cm ³ /g-1cm ³ /g。

In some preferred embodiments of the invention, the contacting is by mixing the HZSM-5 molecular sieve with the aqueous solution containing the carbon source.

In some preferred embodiments of the present invention, the drying treatment is performed after the mixing, and the drying treatment is performed at a temperature of 60 ℃ to 100 ℃ for 6 hours to 24 hours.

In some preferred embodiments of the invention, the temperature of the carbonization treatment is 300 ℃ to 500 ℃, preferably 400 ℃ to 500 ℃; the time is 2h-24h, preferably 10h-20h.

In some preferred embodiments of the invention, the temperature of the sulfonation treatment is from 80 ℃ to 200 ℃, preferably from 120 ℃ to 180 ℃; the time is 2h-10h, preferably 5h-10h.

According to the invention, the carbonized HZSM-5 molecular sieve is sulfonated by concentrated sulfuric acid, wherein the concentrated sulfuric acid is commercially available 98% concentrated sulfuric acid.

In another aspect of the present invention, the solid acid catalyst prepared by the above preparation method is provided, and the content of sulfur element in the catalyst is 0.01mol to 0.05mol, based on 1mol of the total amount of the catalyst.

In a further aspect, the present invention provides the use of the above solid acid catalyst in the field of the preparation of methyl glycolate.

In still another aspect, the present invention provides a process for producing methyl glycolate comprising: in the presence of the solid acid catalyst described above, the following steps are carried out:

the method comprises the following steps: the mixture of organic solvent and organic acid is used as solvent to make formaldehyde and CO produce carbonylation reaction to produce glycolic acid;

step two: the produced glycolic acid and methanol are subjected to esterification reaction to produce methyl glycolate.

According to the invention, the mass ratio of the solid acid catalyst to the formaldehyde is (0.1-10): 1, preferably (1-5): 1.

In some preferred embodiments of the present invention, the reaction temperature of the carbonylation reaction is 70 ℃ to 140 ℃, the reaction pressure is 6MPa to 10MPa, and the reaction time is 1h to 6h; the reaction temperature of the esterification reaction is 80-120 ℃, and the reaction time is 1-4 h.

According to the invention, the organic solvent is selected from at least one of sulfolane, cyclohexane, n-octane and isooctane; the organic acid is acetic acid and/or propionic acid. The molar ratio of the organic acid to the organic solvent is 1.

According to the present invention, trioxymethylene or paraformaldehyde may be used as a source of formaldehyde monomer.

The solid acid catalyst provided by the invention has the advantages of simple preparation, environmental protection, economy, high catalytic activity, reusability and easy separation from a product, has good practicability and economy, and is a good solid acid catalyst for carbonylation reaction.

Drawings

FIG. 1 is a pyridine infrared spectrum of the solid acid catalyst obtained in example 1, wherein B and L represent characteristic peaks of Bronsted and Lewis acid sites, respectively.

FIG. 2 shows NH after recycling of the solid acid catalyst obtained in example 1 ₃ -a TPD profile.

Detailed Description

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to the following description.

The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

The yield of glycolic acid (ester) obtained for the product of the invention is shown as:

yield of glycolic acid (ester) () = molar formation of glycolic acid (ester) (theoretical value)/molar amount of raw material formaldehyde × 100%

Wherein the molar glycolic acid (ester) formation (theoretical) is the amount that theoretically could be converted to useful intermediates in the subsequent hydrogenation of ethylene glycol, i.e., glycolic acid, methyl glycolate, and products of organic carboxylic acid protection of glycolic acid (ester) in solvents including, but not limited to, acetoxyacetic acid, methyl acetoxyacetate, propionyloxyacetic acid, methyl propionyloxyacetate, etc., if acetic acid is used as glycolic acid protector, the products are calculated as:

yield of glycolic acid (ester) (%) = (glycolic acid + methyl glycolate + acetoxyacetic acid methyl ester) mole production/formaldehyde charge × 100%

Example 1

Preparing a 15 mass percent glucose solution as an impregnation solution, taking HZSM-5 as a carrier, mixing the carrier and the impregnation solution, standing for 24 hours after uniform mixing, and then drying for 12 hours at 80 ℃, wherein the volume of the impregnation solution is the same as that of pores of the carrier. Drying the sample at 400 ℃ N ₂ And treating for 10 hours in the atmosphere to obtain the carbonized molecular sieve material. Sulfonating the obtained carbonized molecular sieve material with concentrated sulfuric acid at 150 ℃ for 8h, and then repeatedly washing with deionized water at 80 ℃ until no SO is detected in the washing liquid ₄ ^2- In the presence of (as BaCl) ₂ The solution is used as an indicator), and the catalyst C1 is obtained after drying at 80 ℃.

Example 2

Preparing a sucrose solution with the mass fraction of 30% as an impregnating solution, taking HZSM-5 as a carrier, mixing the carrier and the impregnating solution, standing for 24h after uniform mixing, and then drying at 80 ℃ overnight. Drying the sample at 400 ℃ N ₂ And treating for 10h in the atmosphere to obtain the carbonized molecular sieve material. Sulfonating the obtained carbonized molecular sieve material with concentrated sulfuric acid at 150 ℃ for 10h, and then repeatedly washing with deionized water at 80 ℃ until no SO is detected in the washing liquid ₄ ^2- In the presence of (as BaCl) ₂ The solution is used as an indicator), and the catalyst C2 is obtained after drying at 80 ℃.

Example 3

Catalyst C3 was prepared as in example 1, except that a 10% by weight glucose solution was used as the impregnation solution.

Example 4

Catalyst C4 was prepared as in example 1, except that a 20% by mass glucose solution was used as the impregnation solution.

Example 5

Catalyst C5 was prepared as in example 1, except that a 25% by weight glucose solution was used as the impregnating solution.

Example 6

Catalyst C6 was prepared as in example 1, except that a 30% by mass glucose solution was used as the impregnation solution.

Example 7

Catalyst C7 was prepared as in example 1, except that the volume of the impregnation solution was 0.9 times the pore volume of the support.

Example 8

Catalyst C8 was prepared as in example 1, except that the volume of the impregnation solution was 1.1 times the pore volume of the support.

Example 9

Catalyst C9 was prepared in the manner of example 1, except that the temperature of the carbonization treatment was 300 ℃.

Example 10

Catalyst C10 was prepared in the manner of example 1, except that the temperature of the carbonization treatment was 500 ℃.

Example 11

Catalyst C11 was prepared as in example 1, except that the carbonization treatment time was 2h.

Example 12

Catalyst C12 was prepared as in example 1, except that the carbonization treatment time was 20h.

Comparative example 1

Weighing a certain amount of glucose, adding a proper amount of concentrated sulfuric acid, mixing, placing in a stainless steel pressure kettle with a polytetrafluoroethylene lining, and reacting in an oven at 180 ℃ for 24 hours. Taking out, cooling, and repeatedly washing with deionized water until no SO is detected in the washing liquid ₄ ^2- In the presence of (as BaCl) ₂ The solution is used as an indicator), and the solid acid catalyst C13 prepared by the direct carbonization sulfonation method of the carbohydrate is obtained after drying at the temperature of 80 ℃.

Comparative example 2

Weighing appropriate amount of HZSM-5 solid, adding into toluene solution of 3-mercaptopropyltrimethoxysilane, and reacting in N ₂ Refluxing for 24h under protection, and cooling to room temperature after the reaction is finished. Filtering, and performing Soxhlet extraction with dichloromethane to obtain the sulfhydrylated HZSM-5 molecular sieve. Sulfhydrylated molecular sieves 5g, with 50mL30% of H ₂ O ₂ Mixing, adding two drops of concentrated sulfuric acid and 15mL of anhydrous methanol, reacting at room temperature for 12h, filtering after the reaction is finished, and washing with deionized water to be neutral to obtain the sulfonic acid functionalized HZSM-5 solid acid catalyst C14.

Comparative example 3

A sulfonated carbon molecular sieve was prepared as solid acid catalyst C15 in the manner of example 1 in CN 104874300A.

Comparative example 4

Catalyst C16 was prepared in the manner of example 1, except that the support used was SBA-15 molecular sieve.

Application example 1

The synthesis of methyl glycolate was carried out using the catalysts prepared in examples 1-12 and comparative examples 1-4, respectively. The synthesis method comprises the following steps:

in a stainless steel autoclave having a volume of 100mL, 1.4g of paraformaldehyde and sulfolane were added: acetic acid =5, 20mL of the mixed solvent of. Weighing 2g of catalyst, putting the catalyst into a kettle, sealing the reaction kettle, replacing air in the kettle with CO for 2 times, introducing high-pressure CO to 8MPa, and reacting for 3 hours at 100 ℃. After the reaction is finished, cooling the reaction kettle to room temperature, adding 50mL of methanol, sealing the reaction kettle, reacting at 80 ℃ for 2h, cooling the reaction kettle to room temperature after the reaction is finished, taking out the feed liquid in the reaction kettle, and analyzing by using high performance liquid chromatography. The yield of glycolic acid (ester) is shown in table 1.

TABLE 1

Test items	Carbohydrate compounds	Carrier	Yield of glycolic acid (ester) (%)
				Catalyst C1	Glucose	HZSM-5	70.1
Catalyst C2	Sucrose	HZSM-5	68.7
				Catalyst C3	Glucose	HZSM-5	65.0
Catalyst C4	Glucose	HZSM-5	70.9
				Catalyst C5	Glucose	HZSM-5	68.4
Catalyst C6	Glucose	HZSM-5	66.2
				Catalyst C7	Glucose	HZSM-5	64.4
Catalyst C8	Glucose	HZSM-5	67.3
				Catalyst C9	Glucose	HZSM-5	57.6
Catalyst C10	Glucose	HZSM-5	65.9
				Catalyst C11	Glucose	HZSM-5	49.4
Catalyst C12	Glucose	HZSM-5	68.0
				Catalyst C13	Glucose	Is free of	53.6
Catalyst C14	Is free of	HZSM-5	46.5
				Catalyst C15	Sucrose	SBA-15	40.7
Catalyst C16	Glucose	SBA-15	43.5

Application example 2

Taking the feed liquid after the reaction of the catalyst C1 and the catalyst C13 in the application example 1, carrying out suction filtration and separation, and drying at 60 ℃ to obtain the first recovered catalyst. The synthesis of methyl glycolate was performed again under the conditions in application example 1, and the results are shown in table 2.

And then taking the reacted feed liquid of the catalyst C1 and the catalyst C13 again, carrying out suction filtration and separation, and drying at 60 ℃ to obtain a secondary recovered catalyst. The synthesis of methyl glycolate was performed again under the conditions in application example 1, and the results are shown in table 2.

TABLE 2

According to the data in table 2, the yield of methyl methoxyacetate is not reduced obviously when the catalyst provided by the invention is reused, while the yield of methyl methoxyacetate is reduced obviously when the catalyst of the comparative example is reused, which shows that the catalyst provided by the invention has higher stability.

Analytical example 1

Pyridine infrared characterization is carried out on the solid acid catalyst C1 prepared in example 1, and the obtained pyridine infrared spectrum is shown in figure 1, wherein B and L respectively represent characteristic peaks of Bronsted and Lewis acid sites.

As can be seen from FIG. 1, the catalyst provided by the present invention has a certain acidic site of B acid. .

Analytical example 2

Corresponding to the catalyst C1 used for the first time in example 2,Carrying out NH on the first recovered catalyst and the second recovered catalyst ₃ TPD characterization, NH obtained ₃ The TPD characterization profile is shown in figure 2.

As can be seen from FIG. 2, the catalyst provided by the present invention has better cycle stability.

Analytical example 3

Elemental composition analysis was performed on the catalyst C1 obtained in example 1 and the catalyst C14 obtained in comparative example 2, and the results are shown in table 3.

TABLE 3

As can be seen from table 3, the sulfonic acid group is effectively introduced into the catalyst C1 provided by the present invention, and the content of the sulfonic acid group in the catalyst C1 is higher than that of the catalyst C14 prepared by a conventional method in which expensive reagents and various steps are used.

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. Modifications may be made to the invention as defined within the scope of the claims and modifications may be made without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims

1. The application of a solid acid catalyst in the field of preparation of methyl glycolate, wherein the content of sulfur in the solid acid catalyst is 0.01-0.05 mol based on 1mol of the total amount of the catalyst; the preparation method of the solid acid catalyst comprises the following steps:

c) Sulfonating the carbonized HZSM-5 molecular sieve to prepare the solid acid catalyst;

the temperature of the carbonization treatment is 300-400 ℃; the time is 2-24 h.

2. Use according to claim 1, wherein the carbon source is selected from at least one of sucrose, glucose and fructose.

3. The use according to claim 1, wherein the concentration of the carbon source in the aqueous solution containing the carbon source is 10wt% to 30wt%.

4. The use according to claim 3, wherein the concentration of the carbon source in the aqueous solution containing the carbon source is 15wt% to 25wt%.

5. The use according to any one of claims 1 to 4, wherein the volume of the aqueous solution containing the carbon source is 0.9 to 1.1 times the pore volume of the HZSM-5 molecular sieve.

6. The use of claim 5, wherein the volume of the aqueous solution containing the carbon source is equal to the pore volume of the HZSM-5 molecular sieve.

7. The use according to any one of claims 1 to 4, wherein said contacting is carried out by mixing said HZSM-5 molecular sieve with said aqueous solution containing a carbon source.

8. The use according to claim 7, wherein the drying treatment is carried out after the mixing, and the drying treatment is carried out at a temperature of 60-100 ℃ for 6-24 h.

9. Use according to any one of claims 1 to 4, wherein the carbonization treatment is carried out for a period of time of from 10h to 20h;

the temperature of the sulfonation treatment is 80-200 ℃; the time is 2h-10h.

10. The use according to claim 9, wherein the temperature of the sulfonation treatment is 120 ℃ to 180 ℃; the time is 5-10 h.

11. A process for the production of methyl glycolate comprising: performing the following steps in the presence of the solid acid catalyst of claim 1:

12. The production method according to claim 11, wherein the reaction temperature of the carbonylation reaction is 70 ℃ to 140 ℃, the reaction pressure is 6MPa to 10MPa, and the reaction time is 1h to 6h; the reaction temperature of the esterification reaction is 80-120 ℃, and the reaction time is 1-4 h.