Preparation method for methyl glycolate

Abstract

The present application discloses a preparation method for methyl glycolate. The preparation method comprises: subjecting a raw material containing methyl methoxyacetate, dimethyl ether and water to a hydrolysis reaction under predetermined reaction conditions by means of a reactor loaded with a solid acid catalyst, so as to obtain a product containing methyl glycolate. The addition of dimethyl ether in the preparation method of the present application can not only inhibit the hydrolysis reaction from generating dimethyl ether, but also convert dimethyl ether, a by-product of the reaction of carbonylation of methylal into methyl methoxyacetate, into methanol, thereby completely avoiding the output of dimethyl ether during the entire process of carbonylation / hydrolysis of methylal into methyl glycolate; moreover, the addition of dimethyl ether in the preparation method of the present application can promote the conversion of dimethyl ether into methanol during the hydrolysis reaction, which is conducive to the combined use of mature methanol-to-methylal techniques, thereby achieving the preparation of methyl glycolate from methanol, improving the reliability of the process flow and saving on costs.

Description

A preparation method of methyl glycolate Technical Field

[0001] The present application relates to a method for preparing methyl glycolate, and belongs to the field of catalytic chemistry. Background Art

[0002] Methyl glycolate (HOCH2COOCH3, MG) is an important platform compound. Ethylene glycol can be produced through hydrogenation, glycolic acid can be prepared through hydrolysis, and polyglycolic acid (PGA) can be synthesized through polymerization. Ethylene glycol is a monomer in the widely used polyethylene terephthalate (PET) material, enjoying high market demand. Glycolic acid is an excellent chemical cleaning agent and cosmetics raw material and can also polymerize to produce PGA. On January 1, 2021, the strictest plastic restriction order in history officially came into effect in China. Disposable, non-degradable plastic straws and packaging are now banned. The shift to greener, more environmentally friendly materials is becoming increasingly important, and the biodegradable plastics industry has recently become a hot topic in the market. Polyglycolic acid (PGA) is the simplest linear polyester among polyhydroxyalkanoates (POHLAs). It is a fully biodegradable material and can be synthesized by condensing monomers such as methyl glycolate and glycolic acid. It degrades rapidly in the natural environment under the action of water and microorganisms, with carbon dioxide and water as the final degradation products. In addition, PGA can be degraded in seawater, and its degradation products are harmless to the human body and the environment.

[0003] Methyl glycolate can be produced through the formaldehyde carbonylation process. Although the raw materials are inexpensive and readily available, the process requires high temperature, high pressure, strong liquid acid, and organic solvents. Equipment is susceptible to corrosion, and product purification is difficult, resulting in high industrial production costs. In recent years, with the large-scale industrial application of "coal-to-ethylene glycol" technology, the method of partially hydrogenating the intermediate product dimethyl oxalate to produce methyl glycolate has garnered widespread attention. However, on the one hand, the catalyst for the partial hydrogenation of dimethyl oxalate is still immature, resulting in low conversion efficiency and poor stability; on the other hand, the production process of dimethyl oxalate is long and costly, which seriously restricts the development of this method. Currently, the industrial production technology of methyl glycolate monomer is still immature, resulting in insufficient production capacity and high prices for PGA plastics, limiting its large-scale alternative application.

[0004] In recent years, the molecular sieve-catalyzed carbonylation of methylal to produce methyl methoxyacetate has attracted widespread attention. This reaction offers advantages such as a broad and inexpensive raw material supply, low corrosion during the reaction, and the absence of halogens. Methylal, the raw material, can be produced by oxidizing methanol to formaldehyde, followed by condensation with methanol. This process is mature and industrially feasible, offering high production efficiency. Methanol can be generated from non-petroleum carbon-based resources such as coal, natural gas, biomass, and carbon dioxide. Furthermore, this process can be carried out at relatively low temperatures, resulting in high atom economy. The methyl methoxyacetate product can be hydrolyzed to produce methyl glycolate. This technical route of producing methyl methoxyacetate by carbonylation of methylal produced from non-petroleum carbon-based resources and then hydrolyzing it to produce methyl glycolate holds promise for the large-scale industrial production of PGA monomers.

[0005] Summary of the Invention

[0006] In the carbonylation of methylal to produce methyl methoxyacetate, the methylal disproportionation reaction, which occurs in parallel with the main carbonylation reaction, produces some dimethyl ether. In the hydrolysis of methyl methoxyacetate to produce methyl glycolate, dimethyl ether is also produced through the further dehydration of the resulting methanol. Because the methanol dehydration reaction to produce dimethyl ether is an equilibrium reaction, if the dimethyl ether produced in the carbonylation reaction is fed into the subsequent hydrolysis reaction, it is expected that no additional dimethyl ether will be produced during the reaction process.

[0007] Based on this, the present application provides a method for synthesizing methyl glycolate by co-hydrolyzing methyl methoxyacetate and dimethyl ether. This method not only avoids the production of dimethyl ether during the hydrolysis of methyl methoxyacetate, but also converts dimethyl ether, a byproduct of the methylal carbonylation reaction, into methanol. Methanol can then be directly used as a raw material for currently mature methylal industrial production technology.

[0008] The present application provides a method for preparing methyl glycolate, comprising passing a raw material containing methyl methoxyacetate, dimethyl ether and water through a reactor loaded with a solid acid catalyst, and performing a hydrolysis reaction under predetermined reaction conditions to obtain a product containing methyl glycolate.

[0009] Optionally, the molar ratio of dimethyl ether to methyl methoxyacetate is 0.5:1 to 5:1, and the molar ratio of water to methyl methoxyacetate is 0.5:1 to 5:1; preferably, the molar ratio of dimethyl ether to methyl methoxyacetate is 1:1 to 3:1, and the molar ratio of water to methyl methoxyacetate is 1:1 to 3:1.

[0010] Optionally, the predetermined reaction conditions include: a reaction temperature of 140-210° C., a reaction pressure of 0.1-0.3 MPa, a mass space velocity of methyl methoxyacetate of 0.5-3.0 h -1Preferably, the predetermined reaction conditions include: reaction temperature of 150-190°C, reaction pressure of 0.1-0.2 MPa, mass space velocity of methyl methoxyacetate of 1.0-2.0 h -1 .

[0011] Optionally, the solid acid catalyst is selected from at least one of an acidic molecular sieve catalyst, an acidic resin catalyst, and an acidic metal oxide catalyst.

[0012] Optionally, the acidic molecular sieve catalyst is selected from at least one of an acidic molecular sieve having an MFI structure, an acidic molecular sieve having a FAU structure, an acidic molecular sieve having a FER structure, an acidic molecular sieve having a BEA structure, an acidic molecular sieve having a MOR structure, and an acidic molecular sieve having an MWW structure.

[0013] Optionally, the acidic molecular sieve catalyst is selected from at least one of hydrogenated ZSM-5 molecular sieve, hydrogenated Y molecular sieve, hydrogenated ZSM-35 molecular sieve, hydrogenated β molecular sieve, hydrogenated mordenite molecular sieve, and hydrogenated MCM-22 molecular sieve.

[0014] Optionally, the acidic resin catalyst is a strongly acidic cation exchange resin.

[0015] Optionally, the acidic metal oxide catalyst is SO4 2- / M x O y Type solid superacid catalyst, wherein M is a metal element, and X and Y are natural numbers.

[0016] Optionally, the acidic metal oxide catalyst is SO4 2- / ZrO2 solid superacid catalyst.

[0017] Optionally, the reactor is a fixed bed reactor.

[0018] The beneficial effects of this application include:

[0019] 1) The addition of dimethyl ether to the preparation method of the present application not only inhibits the hydrolysis reaction to produce dimethyl ether, but also converts the dimethyl ether by-product in the carbonylation of methylal to methyl methoxyacetate into methanol, thereby ensuring that there is no net output of dimethyl ether in the entire process of carbonylation / hydrolysis of methylal to methyl glycolate.

[0020] 2) The addition of dimethyl ether in the preparation method of the present application can convert the by-product dimethyl ether into methanol, which is conducive to combining the mature methanol-to-methylal process technology to realize the production of methyl glycolate from methanol, increase the reliability of the process flow and save costs. DETAILED DESCRIPTION

[0021] The endpoints of the ranges disclosed in this application and any values ​​are not limited to the exact ranges or values, and these ranges or values ​​should be understood to include approximate ranges or values. For numerical ranges, the endpoints of each range and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0022] The present application provides a method for preparing methyl glycolate, characterized in that a raw material containing methyl methoxyacetate, dimethyl ether and water is passed through a reactor loaded with a solid acid catalyst and subjected to a hydrolysis reaction under predetermined reaction conditions to obtain a product containing methyl glycolate.

[0023] The reactions of methyl methoxyacetate, dimethyl ether and water mainly include the following reactions: CH3OCH2COOCH3+H2O=HOCH2COOCH3+CH3OH (1) CH3OCH2COOCH3+H2O=CH3OCH2COOH+CH3OH (2) CH3OCH2COOCH3+2 H2O=HOCH2COOH+2 CH3OH (3) CH3OCH3+H2O=2 CH3OH (4)

[0024] The separated methoxyacetic acid (CH3OCH2COOH) and glycolic acid (HOCH2COOH) can be converted into methyl methoxyacetate and methyl glycolate after esterification with methanol.

[0025] The above raw material methyl methoxyacetate can be prepared by carbonylation reaction of methylal, and the reaction equation is as follows: CH3OCH2OCH3+CO=CH3OCH2COOCH3 (5)

[0026] The above-mentioned raw material dimethyl ether can be prepared by the methylal disproportionation reaction accompanying the methylal carbonylation reaction. The reaction equation is as follows: 2 CH3OCH2OCH3=2 CH3OCH3+HCOOCH3 (6)

[0027] It can be seen from the above reaction equations (1), (4), (5) and (6) that methyl methoxyacetate, the main product of the methylal carbonylation reaction, and dimethyl ether, the by-product, are used as reaction raw materials, water is added, and the mixture is introduced into a hydrolysis reactor to convert methylal into methyl glycolate and methanol.

[0028] The separated methanol can be used to prepare methylal. The reactions involved are: 2 CH3OH+O2=2 HCHO+2 H2O (7) 2 CH3OH+HCHO=CH3OCH2OCH3+H2O (8)

[0029] Methanol can be converted into methyl glycolate through the above reaction equations (1), (4), (5), (6), (7), and (8).

[0030] In some embodiments, the molar ratio of dimethyl ether to methyl methoxyacetate is 0.5:1 to 5:1; preferably, the molar ratio of dimethyl ether to methyl methoxyacetate is 1:1 to 3:1.

[0031] In some embodiments, the molar ratio of dimethyl ether to methyl methoxyacetate can be selected from any value of 0.5:1, 1:1, 1.5:1, 2.0:1, 2.5:1, 3.0:1, 3.5:1, 4.0:1, 4.5:1 and 5.0:1, or any range therebetween.

[0032] In some embodiments, the molar ratio of water to methyl methoxyacetate is 0.5:1 to 5:1. The molar ratio of water to methyl methoxyacetate is 1:1 to 3:1.

[0033] In some embodiments, the molar ratio of water to methyl methoxyacetate can be selected from any value of 0.5:1, 1:1, 1.5:1, 2.0:1, 2.5:1, 3.0:1, 3.5:1, 4.0:1, 4.5:1 and 5.0:1, or any range therebetween.

[0034] In some embodiments, the predetermined reaction conditions include a reaction temperature of 140 to 210°C, preferably 150 to 190°C.

[0035] In some embodiments, the reaction temperature can be selected from any value of 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C and 210°C, or any range therebetween.

[0036] In some embodiments, the predetermined reaction conditions include a reaction pressure of 0.1 to 0.3 MPa, preferably 0.1 to 0.2 MPa.

[0037] In some embodiments, the reaction pressure may be selected from any value among 0.1 MPa, 0.15 MPa, 0.20 MPa, 0.25 MPa and 0.30 MPa, or a range determined by any two values.

[0038] In some embodiments, the predetermined reaction conditions include a mass space velocity of methyl methoxyacetate of 0.5 to 3.0 h -1 ; preferably 1.0 to 2.0 h -1 .

[0039] In some embodiments, the mass space velocity of methyl methoxyacetate can be selected from 0.5h -1, 1.0h -1 , 1.5h -1 , 2.0h -1 , 2.5h -1 and 3.0h -1 Any value or any range of values ​​between them.

[0040] In some embodiments, the predetermined reaction conditions include: a reaction temperature of 140 to 210° C., a reaction pressure of 0.1 to 0.3 MPa, a mass space velocity of methyl methoxyacetate of 0.5 to 3.0 h -1 Preferably, the predetermined reaction conditions include: reaction temperature of 150-190°C, reaction pressure of 0.1-0.2 MPa, mass space velocity of methyl methoxyacetate of 1.0-2.0 h -1 .

[0041] In some embodiments, the solid acid catalyst is selected from at least one of an acidic molecular sieve catalyst, an acidic resin catalyst, and an acidic metal oxide catalyst.

[0042] In some embodiments, the acidic molecular sieve catalyst is selected from at least one of an acidic molecular sieve having an MFI structure, an acidic molecular sieve having a FAU structure, an acidic molecular sieve having a FER structure, an acidic molecular sieve having a BEA structure, an acidic molecular sieve having a MOR structure, and an acidic molecular sieve having an MWW structure.

[0043] In some embodiments, the acidic molecular sieve catalyst is selected from at least one of hydrogenated ZSM-5 molecular sieve, hydrogenated Y molecular sieve, hydrogenated ZSM-35 molecular sieve, hydrogenated β molecular sieve, hydrogenated mordenite molecular sieve, and hydrogenated MCM-22 molecular sieve.

[0044] In some embodiments, the acidic molecular sieve catalyst comprises a shaped acidic molecular sieve catalyst.

[0045] In some embodiments, the molded acidic molecular sieve catalyst contains a binder such as aluminum oxide and silicon oxide.

[0046] In some embodiments, the acidic molecular sieve catalyst has a silicon-aluminum ratio of SiO2 / Al2O3=5-200.

[0047] In some embodiments, the acidic resin catalyst is a strongly acidic cation exchange resin.

[0048] In some embodiments, the acidic metal oxide catalyst is SO4 2- / M x O y Type solid superacid catalyst, wherein M x Oy represents a metal oxide, wherein M is a metal element, and X and Y are natural numbers; the values ​​of X and Y are determined by the type of metal M and / or its valence in the metal oxide.

[0049] In some embodiments, the acidic metal oxide catalyst is SO4 2- / ZrO2 solid superacid catalyst.

[0050] In some embodiments, the hydrolysis reaction contains a carrier gas such as nitrogen, argon, helium, or hydrogen.

[0051] In some embodiments, the reactor is a fixed bed reactor.

[0052] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0053] Unless otherwise specified, the raw materials and catalysts in the examples of this application were purchased from commercial sources.

[0054] The reaction analysis method of methyl methoxyacetate, dimethyl ether and water is as follows:

[0055] Products other than glycolic acid and unreacted starting materials were analyzed using an Agilent 7890B gas chromatograph with an FID detector connected to a DB-FFAP capillary column and a TCD detector connected to a Porapak Q packed column. Glycolic acid was analyzed using a liquid chromatograph with a C18 column and a UV detector.

[0056] The conversion rate is calculated based on the number of moles of feed carbon entering and leaving the reactor:

[0057] Methyl methoxyacetate conversion rate = [(mole number of carbon atoms of methyl methoxyacetate in the feed) - (mole number of carbon atoms of methyl methoxyacetate in the discharge)] ÷ (mole number of carbon atoms of methyl methoxyacetate in the feed) × 100%

[0058] Dimethyl ether conversion rate = [(moles of dimethyl ether carbon in the feed) - (moles of dimethyl ether carbon in the output)] ÷ (moles of dimethyl ether carbon in the feed) × 100%

[0059] Selectivity is calculated based on the total molarity of product carbon:

[0060] Methyl glycolate selectivity = (mole number of carbon of methyl glycolate in the output) ÷ (mole number of carbon of all products) × 100%

[0061] Methanol selectivity = (mole number of methanol carbon in the output) ÷ (mole number of carbon in all products) × 100%

[0062] The total carbon molar number of the products refers to the sum of the carbon molar numbers of the other components in the feed after deducting the unreacted methyl methoxyacetate and dimethyl ether starting materials.

[0063] Example 1

[0064] 5g of acidic H-ZSM-5 molecular sieve (SiO2 / Al2O3=50, 20-40 mesh particles) catalyst was loaded into a In the fixed bed reactor, there is Thermocouples were placed in a thermowell. Methyl methoxyacetate and water were fed using a horizontal flow pump, while dimethyl ether was fed using a mass flow meter. After mixing and preheating, the raw materials were fed into the catalyst bed for reaction. The products were collected by condensation, weighed, and analyzed using gas chromatography and liquid chromatography. Non-condensable gases were analyzed online using gas chromatography. Reaction conditions were: reaction temperature = 160°C, reaction pressure = 0.1 MPa, and mass space velocity of methyl methoxyacetate = 1.5 h / min. -1 The molar ratio of dimethyl ether to methyl methoxyacetate was 2:1, and the molar ratio of water to methyl methoxyacetate was 1:1. After 5 days of operation, the reaction results were: methyl methoxyacetate conversion = 29.7%, dimethyl ether conversion = 2.6%, methyl glycolate selectivity = 46.7%, and methanol selectivity = 23.6%.

[0065] Example 2

[0066] 5g of acidic HY molecular sieve (SiO2 / Al2O3=60, 20-40 mesh particles) catalyst was loaded into a In the fixed bed reactor, there is Thermocouple tubes were used. Methyl methoxyacetate and water were fed using a horizontal flow pump, while dimethyl ether was fed using a mass flow meter. After mixing and preheating, the raw materials were fed into the catalyst bed for reaction. The products were collected by condensation, weighed, and analyzed by gas chromatography and liquid chromatography. Non-condensable gases were analyzed online by gas chromatography. Reaction conditions were: reaction temperature = 210°C, reaction pressure = 0.3 MPa, and methyl methoxyacetate mass space velocity = 3.0 h / min. -1 The molar ratio of dimethyl ether to methyl methoxyacetate was 5:1, and the molar ratio of water to methyl methoxyacetate was 4:1. After 5 days of operation, the reaction results were: methyl methoxyacetate conversion = 20.1%, dimethyl ether conversion = 1.2%, methyl glycolate selectivity = 42.5%, and methanol selectivity = 34.6%.

[0067] Example 3

[0068] 5g of acidic H-ZSM-35 molecular sieve (SiO2 / Al2O3=30, 20-40 mesh particles) catalyst was loaded into a In the fixed bed reactor, there is Thermocouple tubes were used. Methyl methoxyacetate and water were fed using a horizontal flow pump, while dimethyl ether was fed using a mass flow meter. After mixing and preheating, the raw materials were fed into the catalyst bed for reaction. The products were collected by condensation, weighed, and analyzed by gas chromatography and liquid chromatography. Non-condensable gases were analyzed online by gas chromatography. Reaction conditions were: reaction temperature = 190°C, reaction pressure = 0.2 MPa, and methyl methoxyacetate mass space velocity = 2.0 h / min. -1 The molar ratio of dimethyl ether to methyl methoxyacetate was 3:1, and the molar ratio of water to methyl methoxyacetate was 3:1. After 5 days of operation, the reaction results were: methyl methoxyacetate conversion = 35.4%, dimethyl ether conversion = 2.4%, methyl glycolate selectivity = 47.9%, and methanol selectivity = 30.0%.

[0069] Example 4

[0070] 5g of acidic H-β molecular sieve (SiO2 / Al2O3=15, 20-40 mesh particles) catalyst was loaded into a In the fixed bed reactor, there is Thermocouple tubes were used. Methyl methoxyacetate and water were fed using a horizontal flow pump, while dimethyl ether was fed using a mass flow meter. After mixing and preheating, the raw materials were fed into the catalyst bed for reaction. The products were collected by condensation, weighed, and analyzed by gas chromatography and liquid chromatography. Non-condensable gases were analyzed online by gas chromatography. Reaction conditions were: reaction temperature = 150°C, reaction pressure = 0.15 MPa, and methyl methoxyacetate mass space velocity = 1.0 h / min. -1 The molar ratio of dimethyl ether to methyl methoxyacetate was 0.5:1, and the molar ratio of water to methyl methoxyacetate was 0.5:1. After 5 days of operation, the reaction results were: methyl methoxyacetate conversion = 25.0%, dimethyl ether conversion = 1.7%, methyl glycolate selectivity = 40.5%, and methanol selectivity = 26.3%.

[0071] Example 5

[0072] 5g of acidic H-MOR molecular sieve (SiO2 / Al2O3=25, 20-40 mesh particles) catalyst was loaded into a In the fixed bed reactor, there is Thermocouple tubes were used. Methyl methoxyacetate and water were fed using a horizontal flow pump, while dimethyl ether was fed using a mass flow meter. After mixing and preheating, the raw materials were fed into the catalyst bed for reaction. The products were collected by condensation, weighed, and analyzed using gas chromatography and liquid chromatography. Non-condensable gases were analyzed online using gas chromatography. Reaction conditions were: reaction temperature = 180°C, reaction pressure = 0.14 MPa, and methyl methoxyacetate mass space velocity = 0.6 h / min. -1The molar ratio of dimethyl ether to methyl methoxyacetate was 1.5:1, and the molar ratio of water to methyl methoxyacetate was 2.5:1. After 5 days of operation, the reaction results were: methyl methoxyacetate conversion = 40.5%, dimethyl ether conversion = 3.0%, methyl glycolate selectivity = 51.1%, and methanol selectivity = 25.2%.

[0073] Example 6

[0074] 5g of acidic H-MCM-22 molecular sieve (SiO2 / Al2O3=18, 20-40 mesh particles) catalyst was loaded into a In the fixed bed reactor, there is Thermocouple tubes were used. Methyl methoxyacetate and water were fed using a horizontal flow pump, while dimethyl ether was fed using a mass flow meter. After mixing and preheating, the raw materials were fed into the catalyst bed for reaction. The products were collected by condensation, weighed, and analyzed by gas chromatography and liquid chromatography. Non-condensable gases were analyzed online by gas chromatography. Reaction conditions were: reaction temperature = 140°C, reaction pressure = 0.12 MPa, and methyl methoxyacetate mass space velocity = 0.5 h / min. -1 The molar ratio of dimethyl ether to methyl methoxyacetate was 1:1, and the molar ratio of water to methyl methoxyacetate was 5:1. After five days of operation, the reaction results were: methyl methoxyacetate conversion = 22.4%, dimethyl ether conversion = 2.5%, methyl glycolate selectivity = 46.2%, and methanol selectivity = 29.5%.

[0075] Example 7

[0076] 5g of DB757 strong acid sulfonic acid exchange resin catalyst with an exchange degree of 3.2mmol / g was loaded into a In the fixed bed reactor, there is Thermocouple tubes were used. Methyl methoxyacetate and water were fed using a horizontal flow pump, while dimethyl ether was fed using a mass flow meter. After mixing and preheating, the raw materials were fed into the catalyst bed for reaction. The products were collected by condensation, weighed, and analyzed by gas chromatography and liquid chromatography. Non-condensable gases were analyzed online by gas chromatography. Reaction conditions were: reaction temperature = 140°C, reaction pressure = 0.11 MPa, and methyl methoxyacetate mass space velocity = 0.65 h / min. -1 The molar ratio of dimethyl ether to methyl methoxyacetate was 1:1, and the molar ratio of water to methyl methoxyacetate was 4:1. After 5 days of operation, the reaction results were: methyl methoxyacetate conversion = 14.2%, dimethyl ether conversion = 1.2%, methyl glycolate selectivity = 39.2%, and methanol selectivity = 28.5%.

[0077] Example 8

[0078] 5g SO42- / ZrO2 (20-40 mesh particles) solid super acid catalyst is filled into the inner diameter In the fixed bed reactor, there is Thermocouples were placed in a thermowell. Methyl methoxyacetate and water were fed using a horizontal flow pump, while dimethyl ether was fed using a mass flow meter. After mixing and preheating, the raw materials were fed into the catalyst bed for reaction. The product was collected by condensation, weighed, and analyzed by gas chromatography and liquid chromatography. Non-condensable gases were analyzed online by gas chromatography. Reaction conditions were: reaction temperature = 160°C, reaction pressure = 0.14 MPa, and methyl methoxyacetate mass space velocity = 0.55 h / min. -1 The molar ratio of dimethyl ether to methyl methoxyacetate was 2:1, and the molar ratio of water to methyl methoxyacetate was 3:1. After 5 days of operation, the reaction results were: methyl methoxyacetate conversion = 11.8%, dimethyl ether conversion = 0.8%, methyl glycolate selectivity = 40.2%, and methanol selectivity = 29.8%.

[0079] Comparative Example 1

[0080] 5g of acidic H-ZSM-5 molecular sieve (SiO2 / Al2O3=50, 20-40 mesh particles) catalyst was loaded into a In the fixed bed reactor, there is Thermocouple tube. Methyl methoxyacetate and water were fed using a horizontal flow pump, and inert helium was introduced via a mass flow meter. After mixing and preheating, the raw materials entered the catalyst bed for reaction. The product was condensed, collected, weighed, and analyzed by gas chromatography and liquid chromatography. Non-condensable gases were analyzed online by gas chromatography. Reaction conditions were: reaction temperature (T) = 160°C, reaction pressure (P) = 0.1 MPa, and methyl methoxyacetate mass hourly velocity (WHSV) = 1.5 h -1 The molar ratio of nitrogen to methyl methoxyacetate (N2 / MMAc) was 2:1, and the molar ratio of water to methyl methoxyacetate (H2O / MMAc) was 1:1. After 5 days of operation, the reaction results were: methyl methoxyacetate conversion = 33.9%, dimethyl ether selectivity = 9.8%, methyl glycolate selectivity = 43.9%, and methanol selectivity = 17.9%.

[0081] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing methyl glycolate, characterized in that: The method comprises the steps of passing raw materials containing methyl methoxyacetate, dimethyl ether and water through a reactor loaded with a solid acid catalyst, and performing a hydrolysis reaction under predetermined reaction conditions to obtain a product containing methyl glycolate.

2. The method according to claim 1, characterized in that The molar ratio of dimethyl ether to methyl methoxyacetate is 0.5:1-5:1, and the molar ratio of water to methyl methoxyacetate is 0.5:1-5:1; preferably, the molar ratio of dimethyl ether to methyl methoxyacetate is 1:1-3:1, and the molar ratio of water to methyl methoxyacetate is 1:1-3:

1.

3. The method according to claim 1, characterized in that The predetermined reaction conditions include: a reaction temperature of 140-210° C., a reaction pressure of 0.1-0.3 MPa, a mass space velocity of methyl methoxyacetate of 0.5-3.0 h -1 Preferably, the predetermined reaction conditions include: reaction temperature of 150-190°C, reaction pressure of 0.1-0.2 MPa, mass space velocity of methyl methoxyacetate of 1.0-2.0 h -1 .

4. The method according to any one of claims 1 to 3, characterized in that The solid acid catalyst is selected from at least one of an acidic molecular sieve catalyst, an acidic resin catalyst, and an acidic metal oxide catalyst.

5. The method according to claim 4, characterized in that The acidic molecular sieve catalyst is selected from at least one of an acidic molecular sieve having an MFI structure, an acidic molecular sieve having an FAU structure, an acidic molecular sieve having an FER structure, an acidic molecular sieve having a BEA structure, an acidic molecular sieve having a MOR structure, and an acidic molecular sieve having an MWW structure.

6. The method according to claim 4, characterized in that The acidic molecular sieve catalyst is selected from at least one of hydrogenated ZSM-5 molecular sieve, hydrogenated Y molecular sieve, hydrogenated ZSM-35 molecular sieve, hydrogenated β molecular sieve, hydrogenated mordenite molecular sieve and hydrogenated MCM-22 molecular sieve.

7. The method according to claim 4, characterized in that The acidic resin catalyst is a strongly acidic cation exchange resin.

8. The method according to claim 4, characterized in that The acidic metal oxide catalyst is SO4 2- / M x O y Type solid superacid catalyst, wherein M is a metal element, and X and Y are natural numbers.

9. The method according to claim 4, characterized in that The acidic metal oxide catalyst is SO4 2- / ZrO2 solid superacid catalyst.

10. The method according to any one of claims 1 to 3, characterized in that The reactor is a fixed bed reactor.