Metal salt functionalized solid acid catalyst for etherification reaction and application thereof

Abstract

The application discloses a metal salt functionalized solid acid catalyst for etherification reaction and application thereof, which can catalyze etherification reaction to synthesize methyl tert-butyl ether under mild conditions and exhibits excellent activity and selectivity. The catalyst is prepared by an in-situ synthesis method with a metal salt-acid solution complex as a culture medium, and the preparation method comprises the following steps: (1) preparation of the metal salt-acid solution complex: taking a metal salt as an active main body, preparing a dilute acid solution as an active functional ligand, fully stirring and dissolving at normal temperature, and preparing the metal salt-acid solution complex; (2) preparation of the metal salt functionalized solid acid catalyst: adopting the in-situ synthesis method, mixing tetraethyl orthosilicate into the metal salt-acid solution complex as the culture medium, adding an additive to stir to form a gel, grinding the gel into a powder after aging, and calcining and activating the powder to generate acid sites, so that the metal salt functionalized solid acid catalyst for etherification reaction is prepared.

Description

Technical Field

[0001] This invention relates to a catalyst and its application, and more specifically to a metal salt functionalized solid acid catalyst for etherification reactions and its application. Background Technology

[0002] Methyl tert-butyl ether (MTBE) is a high-octane, colorless, and transparent liquid with excellent blending properties and stability, making it an ideal gasoline additive. It effectively improves combustion efficiency, inhibits ozone formation, and exhibits good miscibility with gasoline, widely used as a blending component in unleaded, high-octane oxygenated gasoline. Furthermore, MTBE is also an important chemical raw material; it can be used to produce high-purity isobutylene through cracking, which is then used in the production of butyl rubber and other products. With increasing demand, the production technology of MTBE is receiving increasing attention.

[0003] The synthesis of methyl tert-butyl ether mainly involves the etherification reaction of methanol with isobutylene under an acidic catalyst. This etherification process follows an electrophilic addition mechanism, where isobutylene, acting as a proton acceptor, undergoes a protonation reaction to generate a carbocation. This carbocation, as an intermediate, then rapidly reacts with the nucleophile CH3O. - The reaction produces methyl tert-butyl ether. According to this mechanism, the protonation of olefins is an acid-base reaction process. Therefore, a strong acidity of the catalyst and a strong basicity of the olefin are favorable for the reaction. Currently, resin catalysts are widely used in etherification reactions due to their acidity and selectivity, but they also have a series of drawbacks. First, resin catalysts have poor thermal stability; at high temperatures, sulfonic acid groups are easily detached and internal pores collapse, leading to a decrease in catalytic activity. Second, resin catalysts are very sensitive to the ratio of methanol to isobutylene, limiting their applicability under different feedstock ratios. Furthermore, resin catalysts can cause corrosion problems and present challenges in post-use treatment, increasing operating costs and environmental risks. These drawbacks limit the efficiency and stability of resin catalysts in the synthesis of methyl tert-butyl ether, prompting researchers to search for more efficient and stable alternative catalysts to improve the performance of methyl tert-butyl ether synthesis.

[0004] In the prior art, Chinese Patent Publication No. CN101773848A provides an innovative preparation technology for a composite rare earth oxide β-zeolite catalyst. This technology modifies the hydrogen-form β-zeolite using lanthanide rare earth oxides to improve the conversion rate of isobutylene during synthesis, achieving an isobutylene conversion rate of 80% under optimal reaction conditions. However, rare earth oxides are prone to leaching, leading to reduced catalyst activity and stability, making industrial application difficult. Chinese Patent Publication No. CN102992965A provides a method for preparing methyl tert-butyl ether using a niobium-containing solid acid catalyst. This method involves impregnating γ-Al₂O₃ in niobium oxalate solution and sulfuric acid solution, followed by calcination, to prepare the niobium-containing solid acid catalyst. However, niobium oxalate has insufficient thermal stability, limiting its continuous use at high temperatures and making it prone to deactivation. This makes it difficult for this catalyst to meet the requirements for high-temperature stability and long-term durability in industrial applications. Chinese Patent CN108057458A discloses a method for preparing a catalyst for the synthesis of methyl tert-butyl ether. This method involves sulfonating SBA-15 with concentrated sulfuric acid to create active centers in the pores of SBA-15, catalyzing the etherification of methanol and tert-butanol to produce methyl tert-butyl ether. However, the sulfonic acid groups are easily desorbed from the catalyst surface during the reaction, leading to a decrease in catalytic activity. Chinese Patent CN109232196A discloses a method for preparing methyl tert-butyl ether by modifying montmorillonite with metal oxides to enhance its catalytic performance. However, the pores of montmorillonite are easily blocked after loading, affecting the mass transfer efficiency of the catalyst. Furthermore, metal oxides are expensive, resulting in unsatisfactory economic benefits for industrial application.

[0005] Given the challenges faced by existing solid acid catalysts in etherification reactions, such as diffusion problems due to pore size confinement, easy deactivation of active sites, complex preparation processes, high costs, and insufficient thermal stability, these drawbacks limit their industrial application. Therefore, from an industrial application perspective, it is of great significance to develop a highly efficient catalyst, preparation method, and application for the etherification of methanol and isobutylene to synthesize methyl tert-butyl ether. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in existing industrial catalyst technologies by providing a metal salt-functionalized solid acid catalyst for etherification reactions. This catalyst, as a catalyst for etherification reactions, can catalyze the synthesis of methyl tert-butyl ether under mild conditions. It completely solves the problems of diffusion due to pore size limitations, easy deactivation of active sites, complex preparation processes, high costs, and thermal stability issues inherent in existing solid acid catalysts.

[0007] Another object of the present invention is to provide the application of the metal salt functionalized solid acid catalyst for etherification reaction, which can be used to prepare methyl tert-butyl ether in the etherification reaction of methanol and isobutylene. In the etherification reaction of methanol and isobutylene, the catalyst exhibits excellent activity and selectivity, and the prepared product has high quality and good purity.

[0008] This invention is achieved through the following technical solution:

[0009] The metal salt-functionalized solid acid catalyst for etherification reactions of the present invention is prepared by in-situ synthesis using a metal salt-acid solution complex as a culture medium. The preparation method includes the following steps:

[0010] (1) Preparation of metal salt-acid solution complex: Using metal salt as the active host, a dilute acid solution is prepared as the active functional ligand. The solution is stirred and dissolved at room temperature to obtain metal salt-acid solution complex.

[0011] (2) Preparation of metal salt functionalized solid acid catalyst: The above metal salt-acid solution complex is used as a culture medium. Tetraethyl orthosilicate is mixed in, and an auxiliary agent is added and stirred to form a gel. After the gel is aged, it is ground into powder and calcined to activate it to generate acidic sites, so as to obtain the metal salt functionalized solid acid catalyst for etherification reaction.

[0012] A further technical solution of the metal salt functionalized solid acid catalyst for etherification reaction described above in this invention is that the mass ratio of the active metal salt host to the active functional ligand is 1:10-20; the active host metal salt is a Lewis acid metal salt; and the dilute acid solution for the active functional ligand is a sulfuric acid solution. The use of sulfuric acid also provides a certain sulfonation effect, which can effectively enhance the catalyst activity. A further technical solution is that the Lewis acid metal salt is one or a combination of cerium chloride, zirconium chloride, titanium chloride, cerium sulfate, copper sulfate, or ferric sulfate; and the mass fraction of the dilute acid solution is 3%-8%.

[0013] The metal salt functionalized solid acid catalyst for etherification reaction described above in this invention can be further further described as follows: the auxiliary agent is one or a combination of methylcellulose, ethylcellulose, hexadecyltrimethylammonium bromide, guar gum, polyvinyl alcohol, or N,N-dimethylaniline hydrochloride; the molar ratio of the metal salt-acid solution complex, tetraethyl orthosilicate, and the auxiliary agent is 1:0.5-1:0.0001-0.00001.

[0014] The metal salt functionalized solid acid catalyst for etherification reaction described above in this invention can be further described with a calcination temperature of 150-650℃ and a calcination time of 4-6h.

[0015] The application of the metal salt functionalized solid acid catalyst for etherification reaction prepared by the above-described preparation method of the present invention in the preparation of methyl tert-butyl ether by the etherification reaction of methanol and isobutylene.

[0016] The above-described application of the present invention further includes the following steps: In a high-pressure reactor, methanol is first injected as the reaction solvent, followed by the addition of a pre-prepared metal salt functionalized solid acid catalyst for the etherification reaction; after sealing, the reactor is purged three times with nitrogen to thoroughly remove air; then, isobutylene is introduced into the high-pressure reactor, followed by pressurization and heating to carry out the etherification reaction; after the reaction is completed, high-purity methyl tert-butyl ether product is obtained through separation. A further technical solution is that the molar ratio of methanol to isobutylene is 0.8-1.2, the content of the metal salt functionalized solid acid catalyst for the etherification reaction in the reaction solution is 1%-5%wt of methanol, the etherification reaction pressure is 0.6-1.5MPa, the etherification reaction temperature is 60-120℃, and the etherification reaction time is 0.5-1.5h.

[0017] A further technical solution includes the following steps: adding a water-soluble metal complex catalyst, ammonia, and dichloroethane to a reaction apparatus in a specific ratio; heating and controlling the temperature at 100–120°C for a reaction time of 4–20 minutes; after the reaction, ethylenediamine hydrochloride is obtained, which is then neutralized with alkali, and the ethylenediamine product is separated. A further technical solution is that the amount of the water-soluble metal complex catalyst is preferably 0.1–1% of the mass of dichloroethane, wherein the dichloroethane is 1,2-dichloroethane. A further technical solution may also be that the reaction pressure is 1–1.5 MPa, the ammonia concentration is 15–25%, and the ammonia-to-ethane molar ratio is 4–8:1.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The present invention provides a simple and efficient preparation process for a metal salt-functionalized solid acid catalyst for etherification reactions. The active metal salt substrate and an active functional ligand from an acid solution are loaded onto a mesoporous silica-based material via in-situ synthesis, and the finished product is obtained after a single calcination. This method simplifies the preparation process, reduces costs, and utilizes the high specific surface area and porosity of the mesoporous silica substrate to ensure uniform dispersion of the metal salt and high catalytic efficiency. In the etherification reaction of methanol and isobutylene, this catalyst exhibits excellent activity and selectivity, producing a high-quality, high-purity product. The methanol conversion rate in the etherification reaction can reach 99.9%, and the selectivity for methyl tert-butyl ether can reach 99.9%. The functionalized solid acid catalyst prepared from the Lewis acid metal salt-acid solution complex exhibits good catalytic performance in this reaction system. Under the catalytic conditions of this type of catalyst, the conversion rate of the raw materials is high, the selectivity of the product (methyl tert-butyl ether) is high, and the byproducts are minimal. Compared with traditional catalysts, metal salt functionalized solid acid catalysts maintain good catalytic activity and stability even after repeated use, and the feed conversion rate and product yield do not show a significant decline. They effectively overcome the shortcomings of traditional catalysts and have important application value for the production of methyl tert-butyl ether. Detailed Implementation

[0020] The present invention will be further described below with reference to the embodiments, but these embodiments do not limit the scope of protection of the present invention.

[0021] Example 1

[0022] Preparation of metal salt functionalized solid acid catalysts (cerium chloride functionalized solid acid catalysts) for etherification reactions:

[0023] In this embodiment, cerium chloride is used as the active catalyst host and sulfuric acid solution is used as the active functional ligand. 3g of cerium chloride is dissolved in 40ml of 5% (w / w) dilute sulfuric acid solution. After stirring and dissolving, 6.38g of ethyl silicate and 0.4g of polyvinyl alcohol are added. The mixture is stirred at room temperature until a gel is formed. The resulting gel is aged in an oven, ground, and calcined at 200℃ for 5h to obtain a cerium chloride functionalized solid acid catalyst.

[0024] Etherification reaction:

[0025] 20g of methanol was weighed and added to a 100mL high-pressure reactor. The above-mentioned cerium chloride functionalized solid acid catalyst was added at 5% of the methanol mass. The reactor was sealed, purged with nitrogen three times, and then isobutylene was introduced. Under the condition of an alcohol-to-olefin molar ratio of 1, the high-pressure reactor was pressurized to 1.5MPa with nitrogen and heated to 65℃. The reaction of methanol and isobutylene was catalyzed for 1 hour to obtain methyl tert-butyl ether. Gas chromatography analysis showed that the conversion rate of methanol in the etherification reaction was 96.6%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0026] Example 2

[0027] Based on the cerium chloride functionalized solid acid catalyst prepared in Example 1, the reaction conditions for the etherification reaction were specifically adjusted, with the alcohol-to-olefin molar ratio adjusted to 0.9, while keeping other reaction conditions unchanged. This catalyzed reaction of methanol and isobutylene to produce methyl tert-butyl ether. Gas chromatography analysis showed that the methanol conversion rate in the etherification reaction was 100%, and the selectivity for methyl tert-butyl ether was 99.9%.

[0028] Example 3

[0029] Preparation of metal salt functionalized solid acid catalysts (zirconia-functionalized solid acid catalysts) for etherification reactions:

[0030] In this embodiment, zirconium chloride is used as the active catalyst host and sulfuric acid solution is used as the active functional ligand. 3g of zirconium chloride is dissolved in 40ml of 5% (w / w) dilute sulfuric acid solution. After stirring and dissolving, 6.38g of ethyl silicate and 0.4g of polyvinyl alcohol are added. The mixture is stirred at room temperature until a gel is formed. The resulting gel is aged in an oven, ground, and calcined at 200℃ for 5h to obtain a zirconium chloride functionalized solid acid catalyst.

[0031] Etherification reaction:

[0032] 20g of methanol was weighed and added to a 100mL high-pressure reactor. The above-mentioned zirconium chloride functionalized solid acid catalyst was added at 5% of the methanol mass. The reactor was sealed, purged with nitrogen three times, and then isobutylene was introduced. Under the condition of an alcohol-to-olefin molar ratio of 1, the high-pressure reactor was pressurized to 1.5MPa with nitrogen and heated to 65℃. The reaction of methanol and isobutylene was catalyzed for 1 hour to obtain methyl tert-butyl ether. Gas chromatography analysis showed that the conversion rate of methanol in the etherification reaction was 94.3%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0033] Example 4

[0034] Based on the zirconium chloride functionalized solid acid catalyst prepared in Example 3, the reaction conditions for the etherification reaction were specifically adjusted, with the alcohol-to-olefin molar ratio adjusted to 0.9, while keeping other reaction conditions unchanged. This catalyzed reaction of methanol and isobutylene to produce methyl tert-butyl ether. Gas chromatography analysis showed that the methanol conversion rate in the etherification reaction was 99.8%, and the selectivity for methyl tert-butyl ether was 99.9%.

[0035] Example 5

[0036] Preparation of metal salt functionalized solid acid catalysts (titanium chloride functionalized solid acid catalysts) for etherification reactions:

[0037] In this embodiment, titanium chloride is used as the active catalyst host and sulfuric acid solution is used as the active functional ligand. 3g of titanium chloride is dissolved in 40ml of 5% (w / w) dilute sulfuric acid solution. After stirring and dissolving, 6.38g of ethyl silicate and 0.4g of polyvinyl alcohol are added. The mixture is stirred at room temperature until a gel is formed. The resulting gel is aged in an oven, ground, and calcined at 200℃ for 5h to obtain a titanium chloride functionalized solid acid catalyst.

[0038] Etherification reaction:

[0039] 20g of methanol was weighed and added to a 100mL high-pressure reactor. The above-mentioned titanium chloride functionalized solid acid catalyst was added at 5% of the methanol mass. The reactor was sealed, purged with nitrogen three times, and then isobutylene was introduced. Under the condition of an alcohol-to-olefin molar ratio of 1, the high-pressure reactor was pressurized to 1.5MPa with nitrogen and heated to 65℃. The reaction of methanol and isobutylene was catalyzed for 1 hour to obtain methyl tert-butyl ether. Gas chromatography analysis showed that the conversion rate of methanol in the etherification reaction was 93.9%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0040] Example 6

[0041] Based on the titanium chloride functionalized solid acid catalyst prepared in Example 5, the alcohol-to-olefin molar ratio was specifically adjusted to 0.9 for the etherification reaction, while keeping other reaction conditions unchanged. This catalyzed reaction of methanol and isobutylene to produce methyl tert-butyl ether. Gas chromatography analysis showed that the methanol conversion rate in the etherification reaction was 99.2%, and the selectivity for methyl tert-butyl ether was 99.9%.

[0042] Example 7

[0043] Preparation of metal salt functionalized solid acid catalysts (cerium sulfate functionalized solid acid catalysts) for etherification reactions:

[0044] In this embodiment, cerium sulfate is used as the active catalyst host and sulfuric acid solution is used as the active functional ligand. 3g of cerium sulfate is dissolved in 40ml of 5% (w / w) dilute sulfuric acid solution. After stirring and dissolving, 6.38g of ethyl silicate and 0.4g of polyvinyl alcohol are added. The mixture is stirred at room temperature until a gel is formed. The resulting gel is aged in an oven, ground, and calcined at 250℃ for 5h to obtain a cerium sulfate functionalized solid acid catalyst.

[0045] Etherification reaction:

[0046] 20g of methanol was weighed and added to a 100mL high-pressure reactor. The above-mentioned cerium sulfate functionalized solid acid catalyst was added at 5% of the methanol mass. The reactor was sealed, purged with nitrogen three times, and then isobutylene was introduced. Under the condition of an alcohol-to-olefin molar ratio of 1, the high-pressure reactor was pressurized to 1.5MPa with nitrogen and heated to 65℃. The reaction of methanol and isobutylene was catalyzed for 1 hour to obtain methyl tert-butyl ether. Gas chromatography analysis showed that the conversion rate of methanol in the etherification reaction was 94.7%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0047] Example 8

[0048] Based on the cerium sulfate functionalized solid acid catalyst prepared in Example 7, the alcohol-to-olefin molar ratio was specifically adjusted to 0.9 for the etherification reaction, while keeping other reaction conditions unchanged. This catalyzed reaction of methanol and isobutylene to produce methyl tert-butyl ether. Gas chromatography analysis showed that the methanol conversion rate in the etherification reaction was 99.9%, and the selectivity for methyl tert-butyl ether was 99.9%.

[0049] Example 9

[0050] Preparation of metal salt functionalized solid acid catalysts (copper sulfate functionalized solid acid catalysts) for etherification reactions:

[0051] In this embodiment, copper sulfate is used as the active catalyst host and sulfuric acid solution is used as the active functional ligand. 3g of copper sulfate is dissolved in 40ml of 5% (w / w) dilute sulfuric acid solution. After stirring and dissolving, 6.38g of ethyl silicate and 0.4g of polyvinyl alcohol are added. The mixture is stirred at room temperature until a gel is formed. The resulting gel is aged in an oven, ground, and calcined at 250℃ for 5h to obtain a copper sulfate functionalized solid acid catalyst.

[0052] Etherification reaction:

[0053] 20g of methanol was weighed and added to a 100mL high-pressure reactor. The copper sulfate functionalized solid acid catalyst was added at 5% of the methanol mass. The reactor was sealed, purged with nitrogen three times, and then isobutylene was introduced. Under the condition of an alcohol-to-olefin molar ratio of 1, the high-pressure reactor was pressurized to 1.5MPa with nitrogen and heated to 65℃. The reaction of methanol and isobutylene was catalyzed for 1 hour to obtain methyl tert-butyl ether. Gas chromatography analysis showed that the conversion rate of methanol in the etherification reaction was 93.1%, and the selectivity for methyl tert-butyl ether was 99.9%.

[0054] Example 10

[0055] Based on the copper sulfate functionalized solid acid catalyst prepared in Example 9, the alcohol-to-olefin molar ratio was specifically adjusted to 0.9 for the etherification reaction, while keeping other reaction conditions unchanged. This catalyzed reaction of methanol and isobutylene to produce methyl tert-butyl ether. Gas chromatography analysis showed that the methanol conversion rate in the etherification reaction was 99.3%, and the selectivity for methyl tert-butyl ether was 99.9%.

[0056] Example 11

[0057] Preparation of metal salt functionalized solid acid catalysts (ferric sulfate functionalized solid acid catalysts) for etherification reactions:

[0058] In this embodiment, ferric sulfate is used as the active catalyst host and sulfuric acid solution is used as the active functional ligand. 3g of ferric sulfate is dissolved in 40ml of 5% (w / w) dilute sulfuric acid solution. After stirring and dissolving, 6.38g of ethyl silicate and 0.4g of polyvinyl alcohol are added. The mixture is stirred at room temperature until a gel is formed. The resulting gel is aged in an oven, ground, and calcined at 250℃ for 5h to obtain the ferric sulfate functionalized solid acid catalyst.

[0059] Etherification reaction:

[0060] 20g of methanol was weighed and added to a 100mL high-pressure reactor. The above-mentioned ferric sulfate functionalized solid acid catalyst was added at 5% of the methanol mass. The reactor was sealed, purged with nitrogen three times, and then isobutylene was introduced. Under the condition of an alcohol-to-olefin molar ratio of 1, the high-pressure reactor was pressurized to 1.5MPa with nitrogen and heated to 65℃. The reaction of methanol and isobutylene was catalyzed for 1 hour to obtain methyl tert-butyl ether. Gas chromatography analysis showed that the conversion rate of methanol in the etherification reaction was 92.3%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0061] Example 12

[0062] Based on the ferric sulfate functionalized solid acid catalyst prepared in Example 11, the reaction conditions for the etherification reaction were specifically adjusted, with the alcohol-to-olefin molar ratio adjusted to 0.9, while keeping other reaction conditions unchanged. This catalyzed reaction of methanol and isobutylene to produce methyl tert-butyl ether. Gas chromatography analysis showed that the methanol conversion rate in the etherification reaction was 99.1%, and the selectivity for methyl tert-butyl ether was 99.9%.

[0063] Example 13

[0064] A recycling experiment was conducted on the cerium chloride functionalized solid acid catalyst prepared in Example 1, keeping the ratio of raw materials to catalyst and the reaction conditions constant. The results of three cycles were as follows, with an alcohol-to-olefin molar ratio of 1:

[0065] (1) The methanol conversion rate was 96.6%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0066] (2) The methanol conversion rate was 96.5%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0067] (3) The methanol conversion rate was 96.6%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0068] When the catalyst is recycled three times, the methanol conversion rate exceeds 96%, and the selectivity of methyl tert-butyl ether does not decrease.

[0069] Example 14

[0070] A recycling experiment was conducted on the cerium sulfate functionalized solid acid catalyst prepared in Example 7, keeping the ratio of raw materials to catalyst and the reaction conditions constant. The results of three cycles were as follows, with an alcohol-to-olefin molar ratio of 1:

[0071] (1) The methanol conversion rate was 94.6%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0072] (2) The methanol conversion rate was 94.2%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0073] (3) The methanol conversion rate was 94.7%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0074] When the catalyst is recycled three times, the methanol conversion rate exceeds 94%, and the selectivity of methyl tert-butyl ether does not decrease.

[0075] Example 15

[0076] A recycling experiment was conducted on the copper sulfate functionalized solid acid catalyst prepared in Example 9, keeping the ratio of raw materials to catalyst and the reaction conditions constant. The results of three cycles were as follows, with an alcohol-to-olefin molar ratio of 1:

[0077] (1) The methanol conversion rate was 93.2%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0078] (2) The methanol conversion rate was 93.0%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0079] (3) The methanol conversion rate was 93.1%, and the selectivity of methyl tert-butyl ether was 99.9%.

[0080] When the catalyst is recycled three times, the methanol conversion rate exceeds 93%, and the selectivity of methyl tert-butyl ether does not decrease.

[0081] The results of etherification products under different catalysts and reaction conditions in Examples 1-12 are shown in Table 1.

[0082] Table 1 Results of etherification products under different catalysts and reaction conditions in Examples 1-12

[0083]

[0084] Experimental data analysis:

[0085] The results of Examples 1-12 demonstrate that the functionalized solid acid catalyst prepared from the Lewis acid metal salt-acid solution complex exhibits excellent catalytic performance in this reaction system. Under the catalytic conditions of this type of catalyst, the conversion rate of the feedstock is high, the selectivity of the product (methyl tert-butyl ether) is high, and the amount of byproducts is minimal.

[0086] Based on the results of Examples 13-15, three different catalysts from the metal salt functionalized solid acid catalysts were repeatedly used, and the catalysts still maintained high catalytic activity and no decrease in selectivity, which fully verified the stability of the catalysts. They can be reused multiple times and have great potential for industrial application.

Claims

1. A metal salt functionalized solid acid catalyst for etherification reactions, characterized in that, The metal salt functionalized solid acid catalyst is prepared by in-situ synthesis method with a metal salt-acid solution complex as a culture medium, and the preparation method comprises the following steps: (1) preparation of the metal salt-acid solution complex: taking a metal salt as an active main body, preparing a dilute acid solution as an active functional ligand, fully stirring and dissolving at room temperature to prepare the metal salt-acid solution complex; (2) preparation of the metal salt functionalized solid acid catalyst: using the in-situ synthesis method, taking the metal salt-acid solution complex as the culture medium, mixing tetraethyl orthosilicate, adding an additive to form a gel after stirring, grinding the gel into powder after aging, and baking and activating to generate acid sites, so that the metal salt functionalized solid acid catalyst for etherification reaction is prepared. The active main body metal salt is a Lewis acid metal salt.

2. The metal salt functionalized solid acid catalyst for etherification reaction according to claim 1, characterized in that, The mass ratio of the active main body metal salt to the active functional ligand is 1:10-20; and the active functional ligand dilute acid solution is a sulfuric acid solution.

3. The metal salt functionalized solid acid catalyst for etherification reaction according to claim 1, characterized in that, The Lewis acid metal salt is one or a combination of cerium chloride, zirconium chloride, titanium chloride, cerium sulfate, copper sulfate or iron sulfate; and the mass fraction of the dilute acid solution is 3%-8%.

4. The metal salt functionalized solid acid catalyst for etherification reaction according to claim 1, characterized in that, The additive is one or a combination of methyl cellulose, ethyl cellulose, cetyltrimethylammonium bromide, sesbania powder, polyvinyl alcohol or N,N-dimethylaniline hydrochloride; and the molar ratio of the metal salt-acid solution complex, tetraethyl orthosilicate and the additive is 1:0.5-1:0.0001-0.00001.

5. The metal salt functionalized solid acid catalyst for etherification reaction according to claim 1, wherein, The baking temperature is 150-650 DEG C, and the baking time is 4-6 h.

6. Application of the metal salt functionalized solid acid catalyst for etherification reaction prepared by the preparation method of any one of claims 1-5 in the etherification reaction of methanol and isobutene to prepare methyl tert-butyl ether.

7. Use according to claim 6, characterized in that, The method comprises the following steps: in a high-pressure reaction kettle, methanol is first injected as a reaction solvent, and then the metal salt functionalized solid acid catalyst for etherification reaction prepared in advance is added; after sealing, nitrogen is used for three times of replacement to completely remove the air in the kettle; then, isobutene is introduced into the high-pressure reaction kettle, and then the pressure is increased and the temperature is increased to perform the etherification reaction; after the reaction is completed, high-purity methyl tert-butyl ether product is obtained through separation.

8. Use according to claim 7, characterized in that, The molar ratio of the methanol to the isobutene is 0.8-1.2, the content of the metal salt functionalized solid acid catalyst for etherification reaction in the reaction solution is 1%-5% wt of the methanol, the etherification reaction pressure is 0.6-1.5 MPa, the etherification reaction temperature is 60-120 DEG C, and the etherification reaction time is 0.5-1.5 h.

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