Method for preparing vinyl methyl ether from ethylene glycol through ethylene glycol dimethyl ether cracking

Abstract

The invention discloses a method for preparing vinyl methyl ether from ethylene glycol through ethylene glycol dimethyl ether cracking. According to the method, ethylene glycol and methanol are taken as raw materials, monomethyl ether and dimethyl ether and water are generated through acid catalysis etherification, and ethylene glycol monomethyl ether and ethylene glycol dimethyl ether are obtained through cooling and fractional refining. Ethylene glycol monomethyl ether is used as a product or circularly used as an etherification or secondary etherification reaction raw material, and ethylene glycol dimethyl ether is used as a product or used as a cracking reaction raw material; ethylene glycol dimethyl ether is subjected to base catalytic cracking to generate vinyl methyl ether and methanol, a vinyl methyl ether product is obtained through condensation and separation, and methanol is recycled as an etherification or secondary etherification raw material. The ethylene glycol monomethyl ether / dimethyl ether and the vinyl methyl ether are prepared from the cheap and easily available ethylene glycol and methanol by adopting a two-step or three-step reaction process and a material circulation and energy gradient utilization technology, the reaction efficiency and the raw material utilization rate are high, the material and energy consumption is low, and the process is safe and environment-friendly.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical technology, specifically, it relates to a method for preparing vinyl methyl ether from ethylene glycol via the cracking of ethylene glycol dimethyl ether. Background Technology

[0002] Ethylene glycol monomethyl ether (EGME) and ethylene glycol dimethyl ether (GDME) are both important environmentally friendly solvents, receiving increasing attention and application in green chemistry and environmental protection. EGME has low toxicity and volatility, with minimal impact on human health and the environment, and is widely used as a solvent and diluent in industries such as coatings, inks, cleaning agents, and electronics, as well as as an intermediate in organic synthesis and a monomer for materials. GDME is a high-performance aprotic polar solvent, widely used in the chemical industry, pharmaceutical industry, and organic synthesis, primarily in polymer chemistry, electrochemistry, and boron chemistry. It is also used as a solvent for resins and nitrocellulose, a pharmaceutical extractant, and an intermediate in organic synthesis.

[0003] The main methods for preparing EGME include the Williamson synthesis, ethylene oxide ring-opening method, ethylene oxidative addition method, and ethylene glycol etherification method. However, these methods for preparing ethylene glycol methyl ether have problems such as environmental pollution, safety risks, low reaction efficiency, harsh conditions, and poor selectivity.

[0004] Vinyl methyl ether (MVE) has a wide range of applications, primarily as a chemical intermediate and polymerization monomer in the production of glutaraldehyde and polymer materials, coatings, plasticizers, adhesives, and printing inks. In the pharmaceutical industry, it is used to prepare certain drugs or as a pharmaceutical excipient. It is also used in agriculture and daily care products, such as as a pesticide synergist and cosmetic additive. In the materials field, it is used as a comonomer to improve the adhesion, flexibility, and hydrophilicity of polymers. For example, PVM / MA, copolymerized with maleic anhydride, exhibits excellent chemical stability, adhesion, cohesiveness, and film-forming properties, and is non-toxic and harmless to humans. It is widely used as a coating additive, adhesive, pesticide emulsion, medical excipient, detergent, leather tanning, papermaking, and textile sizing agent. It is also used as a dental adhesive and toothpaste additive. Furthermore, it is a raw material for the synthesis of β-lactam, an important antibiotic intermediate. Vinyl methyl ether is a promising chemical product, therefore, developing its clean and efficient synthesis technology is of great significance.

[0005] Currently, the synthetic routes for vinyl ethers include acetylene addition, acetal pyrolysis, vinyl transfer, and alcohol ether cracking. In comparison, the alcohol ether cracking method uses ethylene glycol mono / di ethers as raw materials, dehydrating or de-alcoholizing them under the action of a catalyst to produce vinyl ethers. Its key advantages are: atmospheric pressure operation, high safety; environmental friendliness, with byproducts being only water or alcohol, and no toxic gas emissions, meeting the requirements of green chemistry.

[0006] To date, there are few reports on the preparation of vinyl ethers from the cracking of ethylene glycol ethers. Patent JP3685942B discloses a method for catalyzing this reaction using Cs₂O / SiO₂, but the Cs₂O / SiO₂ catalyst is expensive, easily deactivated, and cannot be regenerated, resulting in low reaction activity and selectivity, leading to high catalyst usage costs and difficulty in maintaining stable operation over long periods. Patent CN111807937B discloses a method for synthesizing vinyl methyl ether from ethylene glycol dimethyl ether using a CaO-MgO catalyst. However, this method uses a single alkaline earth or rare earth oxide solid base catalyst, which has a small specific surface area, low effective utilization of the basic active centers, poor catalytic activity and stability, and is prone to catalyst deactivation, thus lacking practical value.

[0007] Therefore, there is an urgent need to develop safer, more effective, economical, or environmentally friendly methods for preparing EGME / DGME and MVE. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, this invention provides methods for using highly active, highly selective, and inexpensive acidic and basic catalysts for the synthesis of ethylene glycol mono / dimethyl ether via ethylene glycol etherification and for the preparation of vinyl methyl ether via the dealcoholization of ethylene glycol dimethyl ether; and provides methods for using the acidic and basic catalysts to catalyze a two-step or three-step reaction to simultaneously prepare high-value ethylene glycol mono / dimethyl ether and vinyl methyl ether.

[0009] In one aspect, the present invention provides a method for preparing vinyl methyl ether from ethylene glycol via the pyrolysis of ethylene glycol dimethyl ether, the method comprising the reactions shown in formulas (I) to (III):

[0010] HOCH2CH2OH + CH3OH → HOCH2CH2OCH3 + H2O (Ⅰ);

[0011] HOCH2CH2OCH3 + CH3OH → CH3OCH2CH2OCH3 + H2O (II);

[0012] CH3OCH2CH2OCH3 → CH2=CHOCH3 + CH3OH (III);

[0013] The catalysts for the reactions shown in formulas (I) and (II) are acid catalysts, and the acid catalysts are selected from at least one of liquid acid catalysts and solid acid catalysts;

[0014] The catalyst for the reaction shown in formula (III) is a base catalyst, and the base catalyst is x(Ca 1.0 Mg a X b O c )-yY / zZ, where Ca1.0 Mg a X b O c The catalyst is selected as the main catalyst, the promoter Y is selected from at least one of inorganic carbides and inorganic nitrides, and the support Z is selected from at least one of SiO2 and molecular sieves; X is a rare earth element and O is oxygen; x, y and z represent the mass fractions of the main catalyst, promoter and support in the catalyst, respectively; 1.0, a, b and c represent the molar ratios of the corresponding elements Ca, Mg, X and O in the main catalyst, respectively; a=0~5, b=0~0.2; x=50~98wt%, y=2~20wt%, z=0~50wt%.

[0015] Preferably, c is a value that satisfies the valence requirements of elements Ca, Mg, and X.

[0016] Preferably, the liquid acid catalyst is selected from sulfuric acid, phosphoric acid, p-toluenesulfonic acid (PTSA), trifluoromethanesulfonic acid (TfOH), and trifluoromethanesulfonate [M(OTf)]. n [n=1~4, M is a metal ion], bis(trifluoromethanesulfonamide) (TFSI), bis(trifluoromethanesulfonamide) salt [M(NTf2)] n [n=1~4, M is a metal ion], at least one of organotitanate and acidic ionic liquid. More preferably, the liquid acid catalyst is selected from TfOH, TFSI, and M(OTf). n M(NTf2) n Tetrabutyl titanate, diethylene glycol titanium, 1-methylimidazolium trifluoromethanesulfonate, and bis(trifluoromethanesulfonyl)imide-tetraethylammonium; wherein, M is selected from Mg 2+ Al 3+ Ga 3+ In 3+ Fe 3+ Cu 2+ Zn 2+ ,Sc 3+ Y 3+ La 3+ Ce 3+ Sm 3+ and Nd 3+ More preferably, the liquid acid catalyst is selected from TfOH, TFSI, M(OTf)3, and M(NTf2)3; wherein M is selected from Sc 3+ Sm 3+ and Nd 3+ .

[0017] Preferably, the solid acid catalyst is selected from at least one of supported heteropolyacids and their salts, unsupported heteropolyacids and their salts, and silica-alumina molecular sieves. More preferably, the heteropolyacids and their salts are selected from at least one of phosphotungstic acid, phosphomolybdic acid, cesium phosphotungstate, or silver cesium phosphotungstate. More preferably, the solid acid catalyst is selected from Hβ, HMOR, HZSM-5, HZSM-22, HMCM-22, HMCM-49, γ-Al2O3, Nb2O5, H2SeO4, H2TeO4, Nb2O5 / γ-Al2O3, Nb2O5 / HMCM-22, MoO3 / TiO2, WO3 / TiO2, and WO3 / ZrO2. Even more preferably, the solid acid catalyst is selected from H3PW. 12 O 40 Cs 2.5 H 0.5 PW 12 O 40 Cs 0.67 Ag 0.33 H2PW 12 O 40 H3PW 12 O 40 / HMCM-22、Cs 2.5 H 0.5 PW 12 O 40 / SBA-15、Cs 0.67 Ag 0.33 H2PW 12 O 40 / SiO2, HMOR, HZSM-5, HMCM-22 or WO3 / ZrO2.

[0018] Preferably, in the alkaline catalyst, X is selected from at least one element selected from Y, La, Ce, Sm and Nd, Y is selected from SiC, C3N4, BN and Si3N4, Z is selected from SiO2, SBA-15, MCM-48, KIT-6 and CEO-3; a=0.1~2.0, b=0~0.12; x=60~87wt%, y=3~15wt%, z=10~40wt%.

[0019] More preferably, in the alkaline catalyst, X is selected from at least one element selected from La and Ce, Y is selected from SiC and C3N4, Z is selected from SiO2 and SBA-15; a=0.2~1.2, b=0~0.08; x=65~80wt%, y=5~10wt%, z=15~35wt%.

[0020] Preferably, the method further includes a process for preparing an acid catalyst.

[0021] Preferably, the method further includes a process for preparing an alkaline catalyst.

[0022] In one or more embodiments, the molar amount of the main product obtained according to the method is more than 92.8% of the ethylene glycol raw material; wherein the main product is selected from at least one of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether and vinyl methyl ether.

[0023] Preferably, the main product is vinyl methyl ether.

[0024] Preferably, the main products are vinyl methyl ether and ethylene glycol monomethyl ether, with a molar ratio of (1~20):(1~20). More preferably, the main products are vinyl methyl ether and ethylene glycol monomethyl ether, with a molar ratio of (1~10):(1~10). Even more preferably, the main products are vinyl methyl ether and ethylene glycol monomethyl ether, with a molar ratio of (1~5):(1~5).

[0025] Preferably, the main products are vinyl methyl ether and ethylene glycol dimethyl ether, with a molar ratio of (1~20):(1~20). More preferably, the main products are vinyl methyl ether and ethylene glycol dimethyl ether, with a molar ratio of (1~10):(1~10). Even more preferably, the main products are vinyl methyl ether and ethylene glycol dimethyl ether, with a molar ratio of (1~5):(1~5).

[0026] Preferably, the main products are vinyl methyl ether, ethylene glycol monomethyl ether, and ethylene glycol dimethyl ether, with a molar ratio of (1~5):(1~5):(1~5). More preferably, the main products are vinyl methyl ether, ethylene glycol monomethyl ether, and ethylene glycol dimethyl ether, with a molar ratio of (1~3):(1~3):(1~3). Even more preferably, the main products are vinyl methyl ether, ethylene glycol monomethyl ether, and ethylene glycol dimethyl ether, with a molar ratio of (1~2):(1~2):(1~2).

[0027] In one or more embodiments, the method includes the following steps:

[0028] S1. Etherification reaction: A mixture of raw materials containing ethylene glycol and methanol is used to catalyze the etherification reaction shown in formula (I) and formula (II) using an acid catalyst;

[0029] S2. Separation of etherification products: The products of the etherification reaction in step S1 are cooled, washed, and distilled;

[0030] S3. Purification of the etherification product: The distillation product containing ethylene glycol dimethyl ether in step S2 is subjected to distillation; the distillation product containing ethylene glycol monomethyl ether-water azeotrope in step S2 is subjected to membrane separation using a membrane separator composed of multiple sets of permeate membrane modules.

[0031] S4. Cracking reaction and separation of products: The distillation product containing ethylene glycol dimethyl ether in step S3 is used as raw material, and the cracking reaction shown in formula (Ⅲ) is catalyzed by an alkaline catalyst; the cracking reaction product is cooled and washed to obtain vinyl methyl ether.

[0032] In one or more embodiments, the method includes the following steps:

[0033] S1. Etherification reaction: Ethylene glycol is mixed with methanol or ethylene glycol, methanol and recycled material containing ethylene glycol monomethyl ether are mixed and fed into a preheater. The mixture is heated to the reaction temperature by steam generated from the rapid cooling cracking reaction products and then fed into an etherification reactor. The etherification reaction shown in formula (I) and formula (II) is catalyzed by an acid catalyst.

[0034] S2. Separation of etherification products: The etherification products from step S1 are fed into a cooler and cooled to below 30°C with water at 4-10°C. The cooled gaseous material is fed into a methanol washing tower and washed with methanol at 0-10°C. The by-product dimethyl ether is collected from the gas phase of the methanol washing tower, and the washing liquid is used as the raw material for the etherification reaction in step S1. The cooling liquid is fed into a distillation tower and flashed at atmospheric pressure. A mixture of methanol and ethylene glycol dimethyl ether is collected from the top of the tower, and 14-16 wt% ethylene glycol monomethyl ether-84-86 wt% water azeotrope is collected from the side stream. A mixture containing ethylene glycol monomethyl ether and ethylene glycol is collected from the bottom of the tower.

[0035] S3. Purification of Etherification Products: The methanol and ethylene glycol dimethyl ether mixture collected from the top of the distillation column in step S2 is fed into a methanol removal column for atmospheric distillation. The methanol collected from the top of the column is recycled and used as the feedstock for the etherification reaction in step S1. The bottom liquid of the methanol removal column is fed into an ethylene glycol dimethyl ether column for atmospheric or vacuum distillation. The ethylene glycol dimethyl ether collected from the top of the column is used as feedstock for the cracking reaction or partially collected as a product. The bottom material is returned to the distillation column in step S2. The azeotrope collected from the side stream of the distillation column in step S2 is treated by a membrane separator. Ethylene glycol monomethyl ether is collected from the effluent side and recycled as feedstock for the etherification reaction in step S1 or partially collected as a product. The material collected from the bottom of the distillation column in step S2 is recycled back to step S1 as feedstock for the etherification reaction, or fed into an ethylene glycol monomethyl ether distillation column. After vacuum distillation, ethylene glycol monomethyl ether is collected from the top of the column as a product, and the bottom material is recycled as feedstock for the etherification reaction in step S1.

[0036] S4. Cracking Reaction and Product Separation: The ethylene glycol dimethyl ether collected from the ethylene glycol dimethyl ether tower in step S3 is sent to a heat exchanger, where it exchanges heat with the cracking products before being sent to the cracking reactor. The reaction proceeds under the influence of an alkaline catalyst (xCa). 1.0 Mg a X b O cUnder the action of -yY / zZ, a cracking product containing vinyl methyl ether and methanol is generated. The cracking product is sent to a heat exchanger to exchange heat with the cracking reaction feedstock, and then sent to a quench tower with water at 4~10℃ as the cooling medium. The crude vinyl methyl ether is collected from the gas phase and sent to a water washing tower. The product vinyl methyl ether is collected from the top of the water washing tower. The condensate containing methanol and a small amount of ethylene glycol dimethyl ether is recycled as the etherification reaction feedstock in step S1. The steam generated by cooling the cracking product in the quench tower is sent to the preheater in step S1 to heat the etherification reaction feedstock.

[0037] Preferably, in step S2, the mixture collected from the bottom of the distillation column also contains an acid catalyst.

[0038] In one or more embodiments, the method further includes a secondary etherification reaction in step S3': taking the distillation product containing ethylene glycol monomethyl ether from step S2, the membrane separation product containing ethylene glycol monomethyl ether from step S3, and / or the quench tower condensate containing ethylene glycol monomethyl ether from step S4, and catalyzing the etherification reaction shown in formula (II) with an acid catalyst; the reaction product containing ethylene glycol dimethyl ether obtained from the secondary etherification reaction is used as the feedstock for the cracking reaction in step S4.

[0039] In one or more embodiments, the method includes the following steps:

[0040] S1. Etherification reaction: Ethylene glycol is mixed with methanol or ethylene glycol, methanol and recycled material containing ethylene glycol monomethyl ether are mixed and fed into a preheater. The mixture is heated to the reaction temperature by steam generated from the rapid cooling cracking reaction products and then fed into an etherification reactor. The etherification reaction shown in formula (I) and formula (II) is catalyzed by an acid catalyst.

[0041] S2. Separation of etherification products: The etherification products from step S1 are fed into a cooler and cooled to below 30°C with water at 4-10°C. The cooled gaseous material is fed into a methanol washing tower and washed with methanol at 0-10°C. The by-product dimethyl ether is collected from the gas phase of the methanol washing tower, and the washing liquid is used as the raw material for the etherification reaction in step S1. The cooling liquid is fed into a distillation tower and flashed at atmospheric pressure. A mixture of methanol and ethylene glycol dimethyl ether is collected from the top of the tower, and 14-16 wt% ethylene glycol monomethyl ether and 84-86 wt% water azeotrope are collected from the side stream. The bottom of the tower contains ethylene glycol monomethyl ether and ethylene glycol.

[0042] S3. Purification of Etherification Products: The methanol and ethylene glycol dimethyl ether mixture collected from the top of the distillation column in step S2 is fed into a methanol removal column for atmospheric distillation. The methanol collected from the top of the column is recycled and used as feedstock for the etherification reaction in step S1. The bottom liquid of the methanol removal column is fed into an ethylene glycol dimethyl ether column for atmospheric or vacuum distillation. The ethylene glycol dimethyl ether collected from the top of the column is used as feedstock for the cracking reaction or partially collected as a product. The bottom material is returned to the distillation column in step S2. The azeotrope collected from the side stream of the distillation column in step S2 is treated by a membrane separator. Ethylene glycol monomethyl ether is collected from the effluent side and recycled as feedstock for the secondary etherification reaction or partially collected as a product. The material collected from the bottom of the distillation column in step S2 is recycled back to step S1 as feedstock for the etherification reaction, or fed into an ethylene glycol monomethyl ether distillation column for atmospheric or vacuum distillation. The ethylene glycol monomethyl ether collected from the top of the column is used as a product, and the bottom material is recycled as feedstock for the etherification reaction in step S1.

[0043] S3'. Secondary etherification reaction: The distillation product containing ethylene glycol monomethyl ether in step S2, the membrane separation product containing ethylene glycol monomethyl ether in step S3, and / or the quench tower condensate containing ethylene glycol monomethyl ether in step S4 are mixed with methanol and sent to a preheater. The mixture is heated to the reaction temperature by steam generated from the quench cracking reaction product and then sent to a secondary etherification reactor. The etherification reaction shown in formula (II) is catalyzed by an acid catalyst. The product of the secondary etherification reaction is sent to the cooler of step S2.

[0044] S4. Cracking Reaction and Product Separation: The ethylene glycol dimethyl ether collected from the ethylene glycol dimethyl ether tower in step S3 is sent to a heat exchanger, where it exchanges heat with the cracking products before being sent to the cracking reactor. The reaction proceeds under the influence of an alkaline catalyst (xCa). 1.0 Mg a X b O c Under the action of -yY / zZ, a cracking product containing vinyl methyl ether and methanol is generated. The cracking product is sent to a heat exchanger to exchange heat with the cracking reaction feedstock, and then sent to a quench tower with water at 4~10℃ as the cooling medium. Crude vinyl methyl ether is collected from the gas phase and sent to a water washing tower. Vinyl methyl ether product is collected from the top of the water washing tower. The condensate containing methanol and a small amount of ethylene glycol dimethyl ether is recycled as feedstock for the secondary etherification reaction in step S3'. The steam generated by cooling the cracking product in the quench tower is sent to the preheaters of steps S1 and S3' to heat the etherification reaction feedstock.

[0045] Preferably, in steps S1 and S3', the solid acid catalyst is selected from spherical particles with a particle size of 2.0~4.0 mm, cylindrical particles with a particle size of 2.0~3.0 mm and a length of 2.0~4.0 mm, and clover-shaped particles with a particle size of 2.0~3.0 mm and a length of 2.0~4.0 mm.

[0046] Preferably, in step S4, the alkaline catalyst is selected from spherical particles with a particle size of 2.0~4.0 mm, cylindrical particles with a particle size of 2.0~3.0 mm and a length of 2.0~4.0 mm, and clover-shaped particles with a particle size of 2.0~3.0 mm and a length of 2.0~4.0 mm.

[0047] In one or more embodiments, the etherification reaction process in step S1 is selected from batch reactor, continuous reactor, tubular reactor, and trickle bed reactor.

[0048] Preferably, the etherification reaction in step S1 is a batch reaction in a kettle or a continuous reaction in a kettle, and the acid catalyst is a liquid acid catalyst or a solid acid catalyst; the etherification reaction in step S1 is a tubular reaction, and the acid catalyst is a liquid acid catalyst; or, the etherification reaction in step S1 is a trickle bed reaction, and the acid catalyst is a solid acid catalyst.

[0049] In one or more embodiments, the batch reaction conditions for the etherification reaction are: temperature 100~200℃, pressure 0.5~6.0MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.1~5.0:0~1.0:1.0, and reaction time 0.5~10.0h; the continuous reaction conditions, tubular reaction conditions, and trickle bed reaction conditions for the etherification reaction are: temperature 120~220℃, pressure 1.0~7.0MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.1~5.0:0~1.0:1.0, material residence time 0.2~10.0h or feed weight hourly space velocity 0.1~5.0h. -1 .

[0050] Preferably, the batch reaction conditions for the etherification reaction are: temperature 120~190℃, pressure 1.0~5.5MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.2~4.0:0~0.75:1.0, and reaction time 1.0~7.5h. More preferably, the batch reaction conditions for the etherification reaction are: temperature 140~180℃, pressure 1.5~5.0MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.5~3.0:0~0.5:1.0, and reaction time 2.0~5.0h.

[0051] Preferably, the conditions for the etherification reaction in the continuous reactor, tubular reactor, and trickle bed reactor are as follows: temperature 140~210℃, pressure 1.5~6.0MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.2~4.0:0~0.75:1.0, and material residence time 0.5~5.0h or feed weight hourly space velocity 0.2~2.0h. -1 More preferably, the conditions for the continuous batch reaction, tubular reaction, and trickle bed reaction of the etherification reaction are: temperature 160~200℃, pressure 2.0~5.5MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.5~3.0:0~0.5:1.0, material residence time 1.0~4.0h or feed weight hourly space velocity 0.25~1.0h. -1 .

[0052] Preferably, the secondary etherification reaction in step S3' is a batch reaction in a kettle or a continuous reaction in a kettle, and the acid catalyst is a liquid acid catalyst or a solid acid catalyst; the etherification reaction in step S3' is a tubular reaction, and the acid catalyst is a liquid acid catalyst; or, the etherification reaction in step S3' is a trickle bed reaction, and the acid catalyst is a solid acid catalyst.

[0053] Preferably, the batch reaction conditions for the secondary etherification reaction are: temperature 120~200℃, pressure 1.0~6.0MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.2~5.0:1.0:0~0.5, and reaction time 1.0~10.0h. More preferably, the batch reaction conditions for the secondary etherification reaction are: temperature 130~190℃, pressure 1.2~5.5MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.5~4.0:1.0:0~0.2, and reaction time 2.0~8.0h. More preferably, the batch reaction conditions for the secondary etherification reaction are: temperature 140~180℃, pressure 1.5~5.0MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 2.0~3.5:1.0:0~0.1, and reaction time 3.0~5.0h.

[0054] Preferably, the conditions for the secondary etherification reaction in the continuous reactor, tubular reactor, and trickle bed reactor are as follows: temperature 140~220℃, pressure 1.5~7.0MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.2~5.0:1.0:0~0.5, material residence time 0.5~10.0h or feed weight hourly space velocity 0.1~2.0h.-1 More preferably, the conditions for the secondary etherification reaction in the continuous reactor, tubular reactor, and trickle bed reactor are as follows: temperature 150~210℃, pressure 2.0~6.0MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 1.5~4.0:1.0:0~0.2, material residence time 1.0~5.0h or feed weight hourly space velocity 0.2~1.0h. -1 More preferably, the conditions for the secondary etherification reaction in the continuous reactor, tubular reactor, and trickle bed reactor are as follows: temperature 160~200℃, pressure 2.5~5.5MPa, raw material molar ratio n(methanol):n(ethylene glycol monomethyl ether):n(number of hydroxyl groups in ethylene glycol) = 2.0~3.5:1.0:0~0.1, material residence time 2.0~4.0h or feed weight hourly space velocity 0.25~0.5h. -1 .

[0055] In one or more embodiments, in step S4, the pyrolysis reaction is a fixed-bed reaction, and the pyrolysis reaction conditions are a temperature of 360~480℃, a pressure of 0.01~1.00MPa, and a weight hourly space velocity of ethylene glycol dimethyl ether of 0.05~2.00h. -1 .

[0056] Preferably, in step S4, the pyrolysis reaction occurs in an isothermal solid-bed reactor or an adiabatic solid-bed reactor, and the conditions for the pyrolysis reaction are: temperature 380~460℃, pressure 0.05~0.75MPa, and ethylene glycol dimethyl ether weight hourly space velocity 0.10~1.00h. -1 .

[0057] More preferably, in step S4, the pyrolysis reaction occurs in an adiabatic solid-bed reactor, and the conditions for the pyrolysis reaction are: temperature 400~440℃, pressure 0.10~0.50MPa, and ethylene glycol dimethyl ether weight hourly space velocity 0.20~0.80h. -1 .

[0058] In one or more embodiments, in step S2, the distillation column operating conditions are atmospheric pressure, top temperature 83-90°C, side stream temperature 100-110°C, and bottom temperature 120-130°C; in step S3, the methanol removal column operating conditions are atmospheric pressure, top temperature 65-70°C, and bottom temperature 80-85°C, and the ethylene glycol dimethyl ether product column operating conditions are pressure 40-60 kPa, top temperature 68-73°C, and bottom temperature 80-85°C; the ethylene glycol monomethyl ether distillation column operating conditions in step S3 are: pressure 10-101 kPa, top temperature 95-125°C, and bottom temperature 110-140°C.

[0059] In step S3, the permeate membrane is an inorganic permeate membrane, and the azeotrope collected from the distillation column side stream enters the membrane separator directly in gaseous form. The operating conditions for membrane separation are a temperature of 100~110℃, a residual side pressure of 0.2~0.4MPa, and a permeate side pressure ≤2kPa. Alternatively, in step S3, the permeate membrane is an organic permeate membrane, and the azeotrope collected from the distillation column side stream enters the membrane separator in liquid form after condensation. The operating conditions are a temperature of 80~90℃, a residual side pressure of 0.2~0.4MPa, and a permeate side pressure ≤2kPa.

[0060] In another aspect, a catalyst x (Ca 1.0 Mg a X b O c )-yY / zZ,Ca 1.0 Mg a X b O c The catalyst is the main catalyst, Y is an additive selected from inorganic carbides and inorganic nitrides, Z is selected from at least one substance selected from SiO2 and molecular sieves; X is a rare earth element, and O is oxygen; x, y and z represent the mass fraction ratio of the main catalyst, additive and support in the catalyst, respectively; 1.0, a, b and c represent the molar ratio of the corresponding elements Ca, Mg, X and O in the main catalyst, respectively; a=0~5, b=0~0.2; x=50~98wt%, y=2~20wt%, z=0~50wt%.

[0061] In another aspect, the use of a catalyst as described in any embodiment of this document in the preparation of vinyl methyl ether, wherein the catalyst is used to catalyze the cracking of ethylene glycol dimethyl ether to produce vinyl methyl ether.

[0062] Compared with the prior art, the present invention has the following specific beneficial effects:

[0063] 1. This invention uses inexpensive and readily available bulk chemicals ethylene glycol and methanol as starting materials. Through a two-step etherification-cracking (de-alcoholization) reaction process or a three-step etherification-secondary etherification-cracking reaction process and the fractional purification of reaction products, three products with adjustable proportions, namely ethylene glycol monomethyl ether, ethylene glycol dimethyl ether and vinyl methyl ether, can be obtained.

[0064] 2. This invention develops a complete process for the reaction and separation of ethylene glycol mono / dimethyl ether synthesized by ethylene glycol etherification (including secondary etherification) and vinyl methyl ether prepared by ethylene glycol dimethyl ether cracking, as well as the recycling of materials and the cascade utilization of energy throughout the process. This simplifies the product separation process, reduces separation energy consumption, and significantly improves the effective utilization rate of raw materials ethylene glycol and methanol, as well as energy utilization efficiency.

[0065] 3. The product solution of this invention is flexible. It can be adjusted according to market demand by changing process conditions such as raw material ratio, feed space velocity, reaction temperature and system pressure, as well as the amount of ethylene glycol monomethyl ether material used for etherification or secondary etherification reaction and the amount of ethylene glycol dimethyl ether used as raw material for cracking reaction. In this way, the ratio of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether and vinyl methyl ether can be adjusted.

[0066] 4. The method used in this invention is a green process. Except for the water generated by the etherification reaction, the remaining materials are separated and used as products or recycled. The entire process does not involve dangerous processes and is safe and environmentally friendly. The raw material cost, material consumption, energy consumption and catalyst usage cost for producing the three products are low. The catalytic reaction and separation and purification efficiency is high, and the technology and products are highly competitive. Detailed Implementation

[0067] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] Unless otherwise specified, all experimental materials used in the following examples are commercially available.

[0069] In the following examples, liquid acids such as TfOH, TFSI, Sc(OTf)3, Sm(OTf)3, Nd(OTf)3, Sc(NTf2)3, Sm(NTf2)3 and Nd(NTf2)3, and heteropolyacid H3PW were used. 12 O 40 The hydrogen-form zeolite molecular sieves HMOR, HZSM-5, and HMCM-22 with SiO2 / Al2O3=25, the solid superacid WO3 / ZrO2, and the carrier silica gel (SiO2) and mesoporous molecular sieve SBA-15 are all commercially available products.

[0070] In the following examples, the feedstocks and products were analyzed using a gas chromatograph with an FID detector and an RTx-624 capillary column. Etherification reaction products were analyzed offline, while pyrolysis (de-methanolization) reaction products were analyzed online. Feedstock conversion and product selectivity were calculated using the corrected area normalization method.

[0071] In the following examples, the single-pass conversion rate X of ethylene glycol (EG) in the ethylene glycol etherification reaction is... EG ethylene glycol monomethyl ether (EGME) selective S EGME Selectivity of ethylene glycol dimethyl ether (GDME) EGDE The calculation formula is as follows:

[0072]

[0073]

[0074]

[0075] In the following examples, in the secondary etherification reaction of ethylene glycol monomethyl ether, the conversion rate X of ethylene glycol monomethyl ether (EGME) is... EGME Selectivity of ethylene glycol dimethyl ether (GDME) GDME The calculation formula is as follows:

[0076]

[0077]

[0078] The pyrolysis (demethanolization) reaction of ethylene glycol dimethyl ether (GDME) yields a conversion rate X. GDME and vinyl methyl ether (MVE) selective S MVE The calculation formula is as follows:

[0079]

[0080]

[0081] In the following examples, TfOH is trifluoromethanesulfonic acid, TFSI is bis(trifluoromethanesulfonyl)imide, Sc(OTf)3, Sm(OTf)3 and Nd(OTf)3 are scandium trifluoromethanesulfonate, samarium trifluoromethanesulfonate and neodymium trifluoromethanesulfonate, respectively, and Sc(NTf2)3, Sm(NTf2)3 and Nd(NTf2)3 are scandium bis(trifluoromethanesulfonyl)imide, samarium bis(trifluoromethanesulfonyl)imide and neodymium bis(trifluoromethanesulfonyl)imide, respectively.

[0082] In the following examples, the preparation methods of each catalyst are as follows.

[0083] Preparation of heteropolyacid salt powder catalyst: A 0.1 mol / L CsOH aqueous solution was added to H3PW under stirring according to a stoichiometric ratio. 12 O 40 The precipitate was neutralized in an aqueous solution, heated to 80°C and stirred for 2.0 h, evaporated to dryness, and then calcined in an air stream at 300°C for 3 h to obtain Cs. 2.5 H 0.5 PW 12 O 40 Powdered catalyst (CHPW): A 0.1 mol / L aqueous solution of AgNO3 was added to H3PW under stirring according to the stoichiometric ratio. 12 O 40After stirring in an aqueous solution for 2 hours, a 0.1 mol / L CsOH aqueous solution was added to neutralize the precipitate. The temperature was raised to 80℃ and stirring was continued for 2.0 hours. After evaporation to dryness, the precipitate was calcined in an air stream at 300℃ for 3 hours to obtain Cs. 0.67 Ag 0.33 H2PW 12 O 40 Powdered catalyst (CAHPW).

[0084] Preparation of supported heteropolyacid powder catalyst: According to stoichiometric ratio, H3PW at 45℃ was used under stirring. 12 O 40 After impregnating HMCM-22 powder with an equal volume of aqueous solution for 2.0 h, the powder was evaporated to dryness and then calcined in an air stream at 300 °C for 3 h to obtain 25 wt% H3PW. 12 O 40 / HMCM-22 powdered catalyst (HPWZ); according to the stoichiometric ratio, use H3PW at 45℃ with stirring. 12 O 40 SBA-15 powder was impregnated with an equal volume of aqueous solution for 2.0 h, and then a 0.1 mol / L CsOH aqueous solution was slowly added to neutralize the precipitate. The mixture was heated to 80 °C and stirred for another 2.0 h. After evaporation to dryness, the powder was calcined in an air stream at 300 °C for 3 h to obtain 30 wt% CsOH. 2.5 H 0.5 PW 12 O 40 / SBA-15 powdered catalyst (CHPWZ); according to the stoichiometric ratio, use H3PW at 45°C with stirring. 12 O 40 After impregnating silica gel powder with an equal volume of aqueous solution for 2.0 h, 0.1 mol / L silver nitrate aqueous solution was added and stirring continued for 2 h. The precipitate was then neutralized with 0.1 mol / L CsOH aqueous solution. The temperature was raised to 80 °C and stirring continued for 2.0 h. The solution was then evaporated to dryness and calcined in an air stream at 300 °C for 3 h to obtain 35 wt% CsOH. 0.67 Ag 0.33 H2PW 12 O 40 / SiO2 powder catalyst (CAHPWZ).

[0085] Preparation of heteropolyacid catalysts: 5 wt% of pore-forming agent citric acid and 8 wt% of binder methylcellulose were added to the aforementioned powder catalysts (CHPW, CAHPW, HPWZ, CHPWZ and CAHPWZ), respectively. After mixing, the mixture was extruded into clover-shaped particles with a diameter of 2.6 mm and a length of 3.0~4.0 mm. The particles were then calcined in flowing air at 350℃ for 2 h and at 500℃ for 3 h to obtain CHPW, CAHPW, HPWZ, CHPWZ and CAHPWZ catalyst particles, respectively.

[0086] Preparation of alkaline earth-based solid alkali catalysts:

[0087] S1: According to the stoichiometric ratio, add the aqueous solution of lanthanum or cerium nitrate to the mixed powder of Ca(OH)2, Mg(OH)2 and carrier silica gel or SBA-15, impregnate at room temperature for 2 hours under stirring, evaporate to dryness, calcine at 400℃ for 2 hours in an air stream, and then calcine at a constant temperature of 850℃ for 5 hours to obtain the carrier powder loaded with active components.

[0088] S2: According to the stoichiometric ratio, the carrier powder with active components obtained in step S1 is mixed evenly with the auxiliary agent C3N4 or SiC with a particle size of less than 200nm, as well as 5wt% pore-forming agent citric acid and 8wt% binder methylcellulose based on the mass of the carrier powder with active components. The mixture is then extruded into clover-shaped particles with a diameter of 2.6mm and a length of 3.0~4.0mm. The particles are then placed in an air stream and calcined at 350℃ for 2h and 600℃ for 5h to obtain alkaline earth solid alkali catalyst particles. The catalyst number and specific composition are shown in Table 1.

[0089] Table 1: Numbering and Chemical Composition of Alkali Earth Solid Alkali Catalysts

[0090]

[0091] Examples 1-6: Preparation of ethylene glycol mono / dimethyl ether by methyl etherification of ethylene glycol (batch reactor)

[0092] With a molar ratio of n(methanol):n(hydroxyl number of ethylene glycol) = 1.5~3.0 and a catalyst dosage of 1.0~6.0% of the total weight of raw materials (methanol + ethylene glycol), methanol, ethylene glycol, and catalyst (TfOH, TFSI, Sc(OTf)3, Sm(NTf2)3, CAHPW, or HMOR) were added to a 500mL reactor. The etherification reaction was carried out for 3.0~5.0h under stirring, at a temperature of 140~180℃, and a pressure of 2.0~5.0MPa. The specific catalysts, reaction process conditions, and results of each example are shown in Table 2.

[0093] Clearly, all catalysts exhibit good batch etherification reaction activity under the corresponding process conditions. The single-pass conversion rate of ethylene glycol is between 93.8% and 95.2%, and the total selectivity of etherification products is between 97.1% and 98.6%. Among them, the selectivity of ethylene glycol monomethyl ether is 58.5% to 67.2%, and the selectivity of ethylene glycol dimethyl ether is 31.4% to 40.0%. Etherification products are mainly ethylene glycol monomethyl ether.

[0094] Examples 7-10: Preparation of ethylene glycol mono / dimethyl ether by methyl etherification of ethylene glycol (continuous batch reaction)

[0095] With a molar ratio of n(methanol):n(ethylene glycol hydroxyl number) = 1.5 and a catalyst dosage of 1.5~5.0% of the total weight of raw materials (methanol + ethylene glycol), methanol, ethylene glycol, and catalyst (TfOH, Nd(NTf2)3, H3PW) are added. 12 O 40 The catalyst (or HZSM-5) is stirred and mixed to prepare a solution or slurry, which is then continuously fed into a 500mL batch reactor. The etherification reaction is carried out under the conditions of stirring, temperature of 160~200℃, system pressure of 3.0~5.0MPa, and material residence time of 1.5~3.0h. The catalyst, reaction process conditions and results of each example are shown in Table 2.

[0096] It is evident that all catalysts exhibit excellent continuous etherification reaction performance under the corresponding process conditions. The single-pass conversion rate of ethylene glycol ranges from 94.7% to 95.6%, and the total selectivity of etherification products is 97.1% to 98.6%, of which the selectivity of ethylene glycol monomethyl ether is 65.5% to 71.5%, and the selectivity of ethylene glycol dimethyl ether is 27.8% to 33.2%. Etherification products are mainly ethylene glycol monomethyl ether.

[0097] Examples 11-14: Preparation of ethylene glycol mono / dimethyl ether by methyl etherification of ethylene glycol (tubular reaction)

[0098] With a molar ratio of n(methanol):n(hydroxyl number of ethylene glycol) = 2.0~2.5 and a liquid acid catalyst concentration of 2.0~3.0 wt% in the raw materials (methanol + ethylene glycol), methanol, ethylene glycol, and catalyst (TfOH, TFSI, Sm(OTf)3, or Sc(NTf2)3) were stirred to prepare a mixed solution, which was continuously fed into a tubular reactor with an inner diameter of 6 mm and a length of 5000 mm. The etherification reaction was carried out at a reaction temperature of 160~180℃, a system pressure of 3.0~5.0 MPa, and a material residence time of 1.0~2.0 h. The catalysts, reaction process conditions, and results of each embodiment are shown in Table 2.

[0099] It is evident that all catalysts exhibit excellent tubular continuous etherification reaction performance under the corresponding process conditions. The single-pass conversion rate of ethylene glycol ranges from 92.5% to 94.8%, and the total selectivity of etherification products is 98.8% to 99.2%, of which the selectivity of ethylene glycol monomethyl ether is 71.9% to 76.2%, and the selectivity of ethylene glycol dimethyl ether is 22.8% to 27.3%. Due to the short residence time, more ethylene glycol monomethyl ether is present in the etherification products.

[0100] Examples 15-18: Preparation of ethylene glycol mono / dimethyl ether by methyl etherification of ethylene glycol (trickling bed reaction)

[0101] Methanol and ethylene glycol are mixed at a molar ratio of n(methanol):n(hydroxyl number of ethylene glycol) = 2.5~3.0. The mixture is then continuously fed into a micro-trickling bed reactor packed with solid acid particles (catalyst particles with a diameter of 2.6 mm and a length of 3.0~4.0 mm, crushed into 40~60 mesh) catalyst (CHPWZ, CAHPW, HPWZ, or HMCM-22). The reactor is operated at a temperature of 180~200℃, a pressure of 5.0~5.5 MPa, and a feed weight hourly space velocity of 0.25~1.00 h⁻¹. -1 The etherification reaction was carried out under the specified conditions. The catalysts, reaction conditions, and results for each example are detailed in Table 2.

[0102] Table 2: Catalysts, reaction parameters, and reaction results for the preparation of ethylene glycol mono / dimethyl ether by ethylene glycol methyl etherification

[0103]

[0104] As shown in Table 2, all solid acid catalysts (Examples 5, 6, 9, 10, 15-18) exhibited good etherification activity under suitable process conditions. The single-pass conversion of ethylene glycol ranged from 85.2% to 95.8%, and the total selectivity of etherification products was 97.1% to 99.5%. Among them, the selectivity of ethylene glycol monomethyl ether was 57.2% to 80.2%, and the selectivity of ethylene glycol dimethyl ether was 19.3% to 44.0%. Ethylene glycol monomethyl ether was the main product.

[0105] As can be seen from the reaction results of Examples 1-18 in Table 2, regardless of whether a liquid or solid acid catalyst is used, and regardless of whether a batch reactor, continuous reactor, tubular continuous reactor, or trickle bed continuous reactor process is employed, under suitable process conditions (reaction temperature 140-200℃, system pressure 2.0-5.5MPa, methanol to ethylene glycol hydroxyl molar ratio 1.5-3.0, batch reactor reaction time 3.0-5.0h, continuous reactor or tubular reactor material residence time 1.0-4.0h, and trickle bed reactor feed weight hourly space velocity 0.25-1.00h), the reaction yield is optimal. -1 Under different conditions, all exhibited excellent performance in the ethylene glycol methyl etherification reaction, with a single-pass conversion rate of ethylene glycol exceeding 85.2% and a total selectivity of ethylene glycol mono / dimethyl ether greater than 97.1%. However, the ratio of ethylene glycol monomethyl ether to ethylene glycol dimethyl ether varied when different reaction processes and / or catalysts were used. Overall, the product was mainly ethylene glycol monomethyl ether.

[0106] Examples 19-22: Preparation of ethylene glycol dimethyl ether by secondary etherification of ethylene glycol monomethyl ether (batch reactor)

[0107] With a molar ratio of n(methanol):n(ethylene glycol monomethyl ether) = 2.0~3.0 and a catalyst dosage of 2.0~5.0% of the total weight of raw materials (methanol + ethylene glycol monomethyl ether), methanol, ethylene glycol monomethyl ether, and catalyst (TfOH, Nd(NTf2)3, H3PW) are added. 12 O 40 (Or CAHPWZ powder) was added to a 500 mL reactor, and a secondary etherification reaction was carried out at a temperature of 150~180℃ and a pressure of 2.0~5.0 MPa for 4.0~5.0 h with stirring. The catalysts, reaction process conditions and results of each example are shown in Table 3.

[0108] It is evident that all catalysts exhibit good intermittent secondary etherification reaction activity under the corresponding process conditions, with the single-pass conversion rate of ethylene glycol monomethyl ether ranging from 95.8% to 97.8% and the selectivity of ethylene glycol dimethyl ether ranging from 98.3% to 99.2%.

[0109] Examples 23-26: Preparation of ethylene glycol dimethyl ether by secondary etherification of ethylene glycol monomethyl ether (continuous batch reaction)

[0110] A solution or slurry was prepared by mixing methanol, ethylene glycol monomethyl ether, and catalyst (TFSI, Sm(OTf)3, CHPW, or HMCM-22) at a molar ratio of n(methanol):n(ethylene glycol monomethyl ether) = 2.0~3.5 and a catalyst dosage of 2.0~5.0% of the total weight of raw materials (methanol + ethylene glycol monomethyl ether). This solution or slurry was continuously fed into a 500mL batch reactor for secondary etherification under stirring, a reaction temperature of 170~200℃, a system pressure of 2.5~5.5MPa, and a material residence time of 3.0~4.0h. The catalysts, reaction conditions, and results for each example are detailed in Table 3. Table 3 shows that all catalysts exhibited good performance in continuous batch secondary etherification reactions, with a single-pass conversion rate of ethylene glycol monomethyl ether ranging from 95.2% to 97.6% and a selectivity of ethylene glycol dimethyl ether ranging from 96.4% to 99.3%.

[0111] Examples 27-30: Preparation of ethylene glycol dimethyl ether by secondary etherification of ethylene glycol monomethyl ether (pipeline reaction)

[0112] A mixed solution was prepared by stirring methanol, ethylene glycol monomethyl ether, and catalyst (TfOH, TFSI, Nd(OTf)3, or Sm(NTf2)3) at a molar ratio of n(methanol):n(ethylene glycol monomethyl ether) = 2.5 and a liquid acid catalyst concentration of 2.0~3.0 wt% in the feedstock (methanol + ethylene glycol monomethyl ether). This solution was continuously fed into a tubular reactor with an inner diameter of 6 mm and a length of 5000 mm. The secondary etherification reaction was carried out at a reaction temperature of 180~190℃, a system pressure of 4.0~5.0 MPa, and a material residence time of 2.0~3.0 h. The catalysts, reaction process conditions, and results for each embodiment are detailed in Table 3. Clearly, all catalysts exhibited good performance in the tubular continuous secondary etherification reaction, with a single-pass conversion rate of ethylene glycol monomethyl ether between 95.7% and 96.6%, and a selectivity of ethylene glycol dimethyl ether between 98.2% and 99.5%.

[0113] Examples 31-34: Preparation of ethylene glycol dimethyl ether by secondary etherification of ethylene glycol monomethyl ether (trickling bed reaction)

[0114] Methanol and ethylene glycol monomethyl ether are mixed at a molar ratio of n(methanol):n(ethylene glycol monomethyl ether) = 3.0~3.5. The mixture is then continuously fed into a micro-trickling bed reactor packed with solid acid particles (catalyst particles with a diameter of 2.6 mm and a length of 3.0~4.0 mm, crushed into 40~60 mesh) catalyst (CHPWZ, CAHPW, WO3 / ZrO2, or HMOR). The reactor operates at a temperature of 190~200℃, a pressure of 5.0~5.5 MPa, and a feed weight hourly space velocity of 0.25~0.50 h⁻¹. -1 A secondary etherification reaction was then carried out. The catalysts, reaction conditions, and results for each example are detailed in Table 3.

[0115] Table 3: Catalysts, reaction parameters, and reaction results for the secondary etherification of ethylene glycol monomethyl ether to prepare ethylene glycol dimethyl ether.

[0116]

[0117] It is evident that all catalysts exhibit good continuous etherification reaction performance in a trickle bed under the corresponding process conditions, with ethylene glycol single-pass conversion ranging from 94.7% to 98.2% and ethylene glycol dimethyl ether selectivity ranging from 98.2% to 99.3%.

[0118] As can be seen from the reaction results of Examples 19-34 in Table 3, regardless of whether a liquid acid catalyst or a solid acid catalyst is used, and regardless of whether a batch reactor, continuous reactor, tubular continuous reactor, or trickle bed continuous reactor process is used, under suitable process conditions (reaction temperature 150-200℃, system pressure 2.0-5.5MPa, methanol to EGME molar ratio 2.0-3.5, batch reactor reaction time 4.0-5.0h, continuous reactor or tubular reaction residence time 2.0-4.0h, and trickle bed reaction feed weight hourly space velocity 0.25-0.50h), the reaction yield is optimal. -1 Under these conditions, all exhibited excellent activity in the secondary etherification reaction of ethylene glycol methyl ether, with a single-pass conversion rate of ethylene glycol monomethyl ether greater than 94.7%, and the selectivity of the target product ethylene glycol dimethyl ether exceeding 96.4%.

[0119] Examples 35-40: Reactivity evaluation of the demethanolization reaction of ethylene glycol dimethyl ether to prepare vinyl methyl ether

[0120] Ethylene glycol dimethyl ether (GDME) is fed into a preheater and heated to the reaction temperature. It is then fed into a micro-fixed-bed reactor packed with alkaline earth-based solid alkali catalyst Cat-1 to Cat-6 particles (catalyst particles with a diameter of 2.6 mm and a length of 3.0 to 4.0 mm, crushed into 40 to 60 mesh). The reaction is carried out at a temperature of 400 to 440 °C, a pressure of 0.12 to 0.40 MPa, and a weight hourly space velocity of 0.25 to 0.50 h⁻¹. -1 Under the specified conditions, GDME catalytic cracking reaction was carried out to prepare vinyl methyl ether (MVE). The catalysts, reaction process conditions and results of each example are listed in Table 4.

[0121] Table 4 shows that under suitable process conditions (reaction temperature 400~440℃, system pressure 0.12~0.40MPa, GDME feed weight hourly space velocity 0.25~0.50h), -1 Under these conditions, all solid base catalysts exhibited good GDME cracking performance, with GDME single-pass conversion ranging from 84.5% to 89.6% and MVE selectivity from 94.5% to 96.4%.

[0122] Examples 41-42: Stability tests of dimethyl ethylene glycol ether to vinyl methyl ether via methanol removal.

[0123] A fixed-bed single-tube reactor (50 mm inner diameter, 3000 mm height of isothermal section) was filled with Cat-4 or Cat-5 catalyst particles (clover-shaped particles, 2.6 mm in diameter and 3.0-4.0 mm in length) at a loading rate of 5.0 kg. GDME was fed into a preheater and heated to the reaction temperature, then fed into the catalyst-filled fixed-bed single-tube reactor. The reaction was carried out at a temperature of 420 °C, a pressure of 0.2 MPa, and a feed weight hourly space velocity of 0.4 h⁻¹. -1The reaction was carried out under specific conditions to investigate the stability of the GDME demethanolization to MVE reaction.

[0124] As shown in Table 4, after 10h, 100h, and 200h of operation, the single-pass conversion rates of GDME for Cat-4 catalyst were 88.5%, 88.3%, and 88.2%, respectively, and the MVE selectivity were 96.5%, 96.4%, and 96.6%, respectively; while the single-pass conversion rates of GDME for Cat-5 catalyst were 87.3%, 87.2%, and 87.0%, respectively, and the MVE selectivity were 95.6%, 95.6%, and 95.8%, respectively. This indicates that both the solid base catalysts Cat-4 and Cat-5 exhibit good stability in the methanol removal reaction of ethylene glycol dimethyl ether.

[0125] Table 4: Catalysts, reaction conditions, and results for the demethanolization of ethylene glycol dimethyl ether to vinyl methyl ether

[0126]

[0127] Comparative Example 1

[0128] Ca was prepared using the method disclosed in patent CN111807937B. 1.0 Mg 1.0 O2 catalyst was used in the GDME pyrolysis reaction to prepare MVE. The reaction conditions and results are listed in Table 4.

[0129] Table 4 shows that for the GDME cracking and methanol removal reaction, the optimal conditions are: temperature 420℃, pressure 0.20MPa, and GDME feed weight hourly space velocity 0.40h. -1 At 10 h, the single-pass conversion of GDME was 75.6% and the selectivity of MVE was 93.8%. After 50 h, the single-pass conversion of EGME dropped sharply to 37.6%, while the selectivity of MVE remained essentially unchanged at 94.2%. Although the catalyst has high initial activity, its reactivity decreases rapidly, and its reaction stability is poor.

[0130] Example 43: Preparation of vinyl methyl ether using a two-step reaction process of batch etherification and fixed-bed pyrolysis.

[0131] S1. Etherification reaction: With a molar ratio of n(fresh methanol + methanol in recycled material):n(total number of hydroxyl groups of ethylene glycol monomethyl ether and ethylene glycol in fresh ethylene glycol + recycled material) = 2.0, n(ethylene glycol monomethyl ether):n(number of hydroxyl groups of ethylene glycol) = 0.40, and a solid acid powder catalyst CHPW of 4.0 wt% (as a percentage of the total raw material weight), methanol, ethylene glycol, recycled material and catalyst are added to a reactor. The reactor is heated with steam generated from the rapid cooling pyrolysis reaction products under stirring, and the etherification reaction is carried out at a temperature of 180℃ and a pressure of 5.0 MPa for 4.0 h.

[0132] S2. Separation of etherification products: The etherification reaction product from step S11 is fed into a cooler and cooled to 28°C with 5°C water. The gaseous material is fed into a methanol washing tower and washed with methanol at 5°C. The byproduct dimethyl ether is collected from the gas phase. The washing liquid is used as the raw material for the etherification reaction in step S1. After the coolant is filtered to recover the catalyst, the filtrate is fed into a distillation tower and flashed at atmospheric pressure, a top temperature of 85°C, a side stream temperature of 100°C, and a bottom temperature of 120°C. A mixture of methanol and ethylene glycol dimethyl ether is collected from the top of the tower, and a 15wt% ethylene glycol monomethyl ether-85wt% water azeotrope is collected from the side stream. The material containing ethylene glycol monomethyl ether and ethylene glycol is collected from the bottom of the tower and used as the raw material for the etherification reaction in step S1.

[0133] S3. Purification of the etherification product: The mixture of methanol and ethylene glycol dimethyl ether collected from the top of the distillation column in step S2 is fed into a methanol removal column and distilled at atmospheric pressure, a top temperature of 65°C, and a bottom temperature of 80°C. The methanol collected from the top is used as the feedstock for the etherification reaction in step S1. The bottom liquid from the methanol removal column is fed into an ethylene glycol dimethyl ether column and distilled at 50 kPa, a top temperature of 68°C, and a bottom temperature of 80°C. The ethylene glycol dimethyl ether collected from the top is used as the feedstock for subsequent cracking reactions, and the bottom liquid is fed into step S2. Distillation column; The 15wt% ethylene glycol monomethyl ether-85wt% water azeotrope collected from the side stream of the distillation column in step S2 is cooled to 85°C, and the liquid phase feed is sent to a plate and frame membrane separator using a PVA / PAN composite organic permeation membrane. The separator operates at a temperature of 85°C and a pressure of 0.3MPa on the retentate side and a pressure of 1.8kPa on the permeate side. Ethylene glycol monomethyl ether with a water content of ≤0.1% is obtained as the product on the retentate side, and water with a content of >99.9% is collected on the permeate side and sent to the wastewater treatment system.

[0134] S4. Cracking reaction and product separation: The ethylene glycol dimethyl ether obtained in step S3 is fed into a heat exchanger to exchange heat with the cracking reaction products, and then fed into a fixed-bed reactor packed with solid base catalyst particles Cat-1. The reaction is carried out at a temperature of 420℃, a pressure of 0.20 MPa, and a weight hourly space velocity (WHSV) of 0.40 h⁻¹. -1 The pyrolysis reaction is carried out below; the high-temperature pyrolysis reaction product is sent to a heat exchanger to exchange heat with the pyrolysis reaction feed, and then sent to a quench tower with 5°C water as the cooling medium. The crude vinyl methyl ether is collected from the gas phase and sent to a water washing tower. The vinyl methyl ether product is collected from the top of the water washing tower, and the bottom liquid is sent to the wastewater treatment system. The condensate containing methanol and a small amount of ethylene glycol dimethyl ether is recycled as the raw material for the etherification reaction in step S1. The steam generated by the quench tower cooling the pyrolysis reaction product is sent to the preheater in step S1 to heat the raw material for the etherification reaction.

[0135] In the above process, the ethylene glycol monomethyl ether collected by membrane separation in step S3 is used as the product, while all the ethylene glycol dimethyl ether collected from the ethylene glycol dimethyl ether tower is used as cracking feedstock. After separation and reuse of the etherification product and cracking reaction product, the total conversion rate of ethylene glycol is 100%, the molar yields of ethylene glycol monomethyl ether and vinyl methyl ether are 23.5% and 69.5%, respectively, and the total molar yield of the two products is 93.0%.

[0136] Example 44: Preparation of vinyl methyl ether using a two-step reaction process of continuous batch etherification and fixed-bed pyrolysis.

[0137] S1. Etherification reaction: Methanol, ethylene glycol, and recycled materials are mixed in a molar ratio of n(fresh methanol + methanol in recycled material):n(fresh ethylene glycol + total number of hydroxyl groups of ethylene glycol monomethyl ether and ethylene glycol in recycled material) = 1.5 and n(ethylene glycol monomethyl ether):n(number of hydroxyl groups of ethylene glycol) = 0.50. 10% of the raw materials are used to prepare a solid acid catalyst CAHPW slurry, with the catalyst dosage being 5.0 wt% of the feed amount (methanol + ethylene glycol + recycled material). The remaining 90% of the raw materials are sent to a heat exchanger to exchange heat with the etherification reaction products, and then sent to a preheater to be heated to the reaction temperature by steam generated from the cracking reaction products in the step quench tower. Simultaneously, the catalyst slurry and the preheated raw materials are continuously fed into a batch reactor, and the etherification reaction is carried out under the conditions of stirring, reaction temperature of 190℃, system pressure of 4.5MPa, and material residence time of 3.0h.

[0138] S2. The separation of the etherified product is the same as S2 in Example 43, except that the separation process is a continuous process.

[0139] S3. The purification of the etherification product is the same as S3 in Example 43, except that the purification process is a continuous process; 50% of the ethylene glycol dimethyl ether collected from the top of the ethylene glycol dimethyl ether column is used as the product, and the other 50% is used as the raw material for the subsequent cracking reaction; and all of the ethylene glycol monomethyl ether collected from the membrane separation is used as the raw material for the etherification reaction in step S1.

[0140] S4. Cracking reaction and product separation: The operation process is the same as S4 in Example 43, except that the cracking reaction uses solid base catalyst particles Cat-2, the reaction temperature is 400℃, the system pressure is 0.40 MPa, and the weight hourly space velocity of ethylene glycol dimethyl ether is 0.50 h⁻¹. -1 .

[0141] In the above process, all ethylene glycol monomethyl ether collected from membrane separation in step S3 is recycled as feedstock for the etherification reaction. 50% of the ethylene glycol dimethyl ether collected from the top of the ethylene glycol dimethyl ether column is used as a product. After separation and reuse of the etherification and pyrolysis reaction products, the total conversion rate of ethylene glycol is 100%, and the molar yields of ethylene glycol dimethyl ether and vinyl methyl ether are 48.8% and 45.8%, respectively, with a total molar yield of 94.6% for both products.

[0142] Example 45 Preparation of vinyl methyl ether using a two-step reaction process of tubular etherification and fixed-bed pyrolysis

[0143] S1. Etherification reaction: With a molar ratio of n(fresh methanol + methanol in recycled material):n(total number of hydroxyl groups of ethylene glycol monomethyl ether and ethylene glycol in fresh ethylene glycol + recycled material) = 2.5, n(ethylene glycol monomethyl ether):n(number of hydroxyl groups of ethylene glycol) = 0.25, and a liquid acid catalyst TfOH concentration of 2.5wt% in the raw materials (methanol + ethylene glycol + recycled material), methanol, ethylene glycol, recycled material and catalyst are mixed and fed into a heat exchanger to exchange heat with the etherification reaction products. Then, the mixture is continuously fed into a tubular reactor and heated by steam generated from the rapid cooling cracking reaction products. The etherification reaction is carried out at a reaction temperature of 200℃, a system pressure of 5.0MPa and a material residence time of 3.0h.

[0144] S2. Separation of etherification products: The etherification reaction products from step S1 are continuously fed into a cooler and cooled to 28°C with water at 5°C. The gaseous material is fed into a methanol washing tower and washed with methanol at 5°C. The byproduct dimethyl ether is collected from the gas phase, and the washing liquid is used as the raw material for the etherification reaction in step S1. The coolant is fed into a distillation tower and flashed at atmospheric pressure, a top temperature of 85°C, a side stream temperature of 110°C, and a bottom temperature of 125°C. A mixture of methanol and ethylene glycol dimethyl ether is collected from the top of the tower, and a 15wt% ethylene glycol monomethyl ether-85wt% water azeotrope is collected from the side stream. The material containing ethylene glycol monomethyl ether and acid catalyst is collected from the bottom of the tower and recycled as the raw material for the etherification reaction in step S1.

[0145] S3. Purification of the etherification product: The mixture of methanol and ethylene glycol dimethyl ether collected from the distillation column in step S2 is fed into a methanol removal column and distilled at atmospheric pressure, a top temperature of 65°C, and a bottom temperature of 80°C. The methanol collected from the top is used as the feedstock for the etherification reaction in step S1. The bottom liquid from the methanol removal column is fed into an ethylene glycol dimethyl ether column and distilled at 50 kPa, a top temperature of 68°C, and a bottom temperature of 80°C. The ethylene glycol dimethyl ether collected from the top is used as a product, with 50% retained as the product and the other 50% used as feedstock for subsequent cracking reactions. The bottom material is fed into the distillation column in step S2. The 15wt% ethylene glycol monomethyl ether-85wt% water azeotrope collected from the side stream of the distillation column in step S2 is fed into a NaA type inorganic molecular sieve permeate membrane separator via gas phase feed. The dehydration temperature is 110℃, the osmotic pressure is 0.2MPa and the permeate pressure is 1.0kPa. Ethylene glycol monomethyl ether with a water content ≤0.1% is obtained from the osmotic side as the product, and water with a content >99.9% is collected from the permeate side and sent to the wastewater treatment system.

[0146] S4. Cracking reaction and product separation: The operation process is the same as S4 in Example 43, except that the cracking reaction uses solid base catalyst particles Cat-3, the reaction temperature is 440℃, the system pressure is 0.20MPa, and the weight hourly space velocity of ethylene glycol dimethyl ether is 0.75h. -1 .

[0147] In the above process, ethylene glycol monomethyl ether collected from membrane separation in step S3 is used as the product, and 50% of the ethylene glycol dimethyl ether collected from the top of the ethylene glycol dimethyl ether column is used as the product. After separation and recycling of the etherification and pyrolysis reaction products, the total conversion rate of ethylene glycol is 100%, and the molar yields of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, and vinyl methyl ether are 24.6%, 36.9%, and 33.7%, respectively, with a total molar yield of 95.2% for the three products.

[0148] Example 46: Preparation of vinyl methyl ether using a two-step reaction process of trickle-bed etherification and fixed-bed pyrolysis.

[0149] S1. Etherification Reaction: Methanol, ethylene glycol, recycled materials, and catalyst are mixed at a molar ratio of n(fresh methanol + methanol in the recycled material):n(fresh ethylene glycol + total hydroxyl count of ethylene glycol monomethyl ether and ethylene glycol in the recycled material) = 3.0 and n(ethylene glycol monomethyl ether):n(hydroxyl count of ethylene glycol) = 0.20. The mixture is then fed into a heat exchanger to exchange heat with the etherification reaction products. The mixture is then heated to the reaction temperature using steam generated from the rapid cooling and cracking reaction products, and continuously fed into a fixed-bed reactor packed with solid acid catalyst particles HZSM-5. The reaction is carried out at a temperature of 200℃, a pressure of 5.5 MPa, and a weight hourly space velocity of 0.25 h⁻¹. -1 The etherification reaction is carried out under the specified conditions.

[0150] S2. The separation process of the etherification product is the same as step S2 in Example 45, except that: since the catalyst HZSM-5 is a solid, the coolant can be directly separated from the catalyst before being fed into the distillation column, so the material taken out of the distillation column bottom does not contain the catalyst; the material containing ethylene glycol monomethyl ether taken out of the distillation column bottom is recycled back to the distillation column by 50%, and the other 50% is recycled as the raw material for the etherification reaction in step S1.

[0151] S3. The purification of the etherification product is the same as step S3 in Example 45, except that all the ethylene glycol monomethyl ether collected from the permeate side of the membrane separator is used as the product.

[0152] S4. Cracking reaction and product separation: The operation process is the same as S4 in Example 43, except that: solid base catalyst particles Cat-4 are used, the reaction temperature is 420℃, the system pressure is 0.20MPa, and the weight hourly space velocity of ethylene glycol dimethyl ether is 0.25h. -1 .

[0153] In the above process, 50% of the ethylene glycol monomethyl ether collected from the distillation column in step S2 is used as etherification feedstock, and the ethylene glycol monomethyl ether collected from the membrane separation in step S3 is used as the product. 50% of the ethylene glycol dimethyl ether collected from the ethylene glycol dimethyl ether column is also used as the product. After separation and recycling of the etherification and pyrolysis reaction products, the total conversion rate of ethylene glycol is 100%, and the molar yields of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, and vinyl methyl ether are 40.6%, 29.2%, and 26.0%, respectively, with a total molar yield of 95.8% for the three products.

[0154] Example 47: A two-step reaction process using trickle-bed etherification and fixed-bed pyrolysis.

[0155] S1. Etherification reaction: Same as step S1 in Example 46, except that: the molar ratio n(fresh methanol + methanol in the recycled material):n(number of hydroxyl groups in fresh ethylene glycol + ethylene glycol in the recycled material) = 1.5; methanol, ethylene glycol, recycled material, and catalyst are mixed; the reaction temperature is 180°C, the pressure is 4.0 MPa, and the weight hourly space velocity is 0.40 h⁻¹. -1 .

[0156] S2. Separation of etherification products: Same as step S2 in Example 46, except that: the material containing ethylene glycol monomethyl ether and ethylene glycol is collected from the bottom of the distillation column and sent to the rectification column. The material is rectified at atmospheric pressure, a top temperature of 125°C and a bottom temperature of 140°C. Ethylene glycol monomethyl ether is collected from the top of the column as the product, and the material from the bottom of the column is recycled as the raw material for the etherification reaction in step S1.

[0157] S3. Purification of the etherification product: Same as step S3 in Example 46, except that all of the ethylene glycol dimethyl ether is used as a raw material for the subsequent cracking reaction.

[0158] S4. Pyrolysis reaction and separation of its products: Same as step S4 in Example 46.

[0159] In the above process, the ethylene glycol monomethyl ether collected from the distillation column in step S2 and the ethylene glycol monomethyl ether collected from the membrane separation in step S3 are all used as products, while the ethylene glycol dimethyl ether collected from the ethylene glycol dimethyl ether column in step S3 is all used as cracking feedstock. After separation and recycling of the etherification and cracking reaction products, the total conversion rate of ethylene glycol is 100%, the molar yields of ethylene glycol monomethyl ether and vinyl methyl ether are 72.6% and 21.6%, respectively, and the total molar yield of the two products is 94.2%.

[0160] Example 48: Preparation of vinyl methyl ether using a three-step reaction process of batch etherification / secondary etherification and fixed-bed pyrolysis.

[0161] S1. Etherification reaction: With a molar ratio of n(fresh methanol + methanol in recycled material):n(number of hydroxyl groups in ethylene glycol) = 1.8 and a liquid acid catalyst Sm(OTf)3 concentration of 3.0 wt% in the raw materials (methanol + ethylene glycol + recycled material), the raw materials methanol, ethylene glycol, recycled material and catalyst are added to the reactor. The reactor is heated with steam generated from the rapid cooling pyrolysis reaction products under stirring, and the etherification reaction is carried out at a temperature of 160℃ and a pressure of 4.0 MPa for 5.0 h.

[0162] S2. Separation of Etherification Products: The etherification reaction product from step S1 is fed into a cooler and cooled to 28°C with 5°C water. The gaseous material is fed into a methanol washing tower and washed with 5°C methanol. The byproduct dimethyl ether is collected from the gas phase, and the washing liquid is used as the raw material for the etherification reaction in step S1. The cooling liquid is fed into a distillation tower and flashed at atmospheric pressure, a top temperature of 85°C, a side stream temperature of 110°C, and a bottom temperature of 125°C. A mixture of methanol and ethylene glycol dimethyl ether is collected from the top of the tower, and a 15wt% ethylene glycol monomethyl ether-85wt% water azeotrope is collected from the side stream. The material containing ethylene glycol monomethyl ether, ethylene glycol, and an acid catalyst is collected from the bottom of the tower and used as the raw material for the subsequent secondary etherification reaction.

[0163] S3. Purification of the etherification product: The mixture of methanol and ethylene glycol dimethyl ether collected from the distillation column in step S2 is fed into a methanol removal column and distilled at atmospheric pressure, a top temperature of 65°C, and a bottom temperature of 80°C. The methanol collected from the top is recycled as feedstock for the etherification reaction in step S1. The bottom liquid from the methanol removal column is fed into an ethylene glycol dimethyl ether column and distilled at a pressure of 50 kPa, a top temperature of 68°C, and a bottom temperature of 80°C. Of the ethylene glycol dimethyl ether collected from the top, 50% is used as the product, and the remaining 50% is used as the product. The bottom material is fed into the distillation column of step S2 as a feedstock for subsequent cracking reactions. The azeotrope collected from the side stream of the distillation column in step S2 is fed into a NaA type inorganic molecular sieve permeate membrane separator in the gas phase. The dehydration temperature is 110℃, the osmotic pressure is 0.2MPa and the permeate pressure is 1.0kPa. The osmotic side yields ethylene glycol monomethyl ether with a water content ≤0.1% as a product, and the permeate side collects water with a content >99.9% and sends it to the wastewater treatment system.

[0164] S3'. Secondary etherification reaction: With a molar ratio of n(fresh methanol + methanol in the recycled material):n(total number of hydroxyl groups of ethylene glycol + ethylene glycol monomethyl ether in the recycled material) = 2.0, n(ethylene glycol monomethyl ether):n(number of hydroxyl groups of ethylene glycol) = 20.0, and a liquid acid catalyst Sm(OTf)3 concentration of 3.0 wt% in the raw material (methanol + recycled material), the mixture containing ethylene glycol monomethyl ether, ethylene glycol, and acid catalyst collected from the bottom of the distillation column in step S2 and the acetaldehyde removal column bottom liquid are added to the reactor. The amount of methanol and the catalyst concentration are adjusted, and the reactor is heated with steam generated from the rapid cooling cracking reaction product under stirring. The secondary etherification reaction is carried out at a temperature of 180℃ and a pressure of 5.0 MPa for 4.0 h. The secondary etherification reaction product is sent to the cooler of step S2.

[0165] S4. Cracking reaction and product separation: The ethylene glycol dimethyl ether obtained in step S3 is fed into a heat exchanger to exchange heat with the cracking reaction products, and then fed into a fixed-bed reactor packed with Cat-5 solid base catalyst particles. The reaction is carried out at a temperature of 440℃, a pressure of 0.12MPa, and a weight hourly space velocity (WHSV) of 0.50h for ethylene glycol dimethyl ether. -1 The cracking reaction is carried out below; the high-temperature cracking reaction product is sent to a heat exchanger to exchange heat with the cracking reaction feed (ethylene glycol dimethyl ether), and then sent to a quench tower with 5°C water as the cooling medium. The crude vinyl methyl ether is collected from the gas phase and sent to a water washing tower. The product vinyl methyl ether is collected from the top of the water washing tower, and the bottom liquid is sent to the wastewater treatment system. The condensate containing methanol and a small amount of ethylene glycol dimethyl ether is recycled as the feedstock for the secondary etherification reaction in step S3'. The steam generated by cooling the cracking reaction product in the quench tower is sent to the preheaters of steps S1 and S3' to heat the feedstock for the etherification and secondary etherification reactions.

[0166] In the above process, the ethylene glycol monomethyl ether collected from the membrane separation in step S3 is used as the product, and 50% of the ethylene glycol dimethyl ether collected from the ethylene glycol dimethyl ether tower is also used as the product. After separation and recycling of the etherification, secondary etherification, and pyrolysis reaction products, the total conversion rate of ethylene glycol is 100%, and the molar yields of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, and vinyl methyl ether are 29.8%, 33.5%, and 31.2%, respectively, with a total molar yield of 94.5% for the three products.

[0167] Example 49: Preparation of vinyl methyl ether using a three-step reaction process of continuous batch etherification / secondary etherification and fixed-bed pyrolysis.

[0168] S1. Etherification reaction: With a molar ratio of n(fresh methanol + methanol in the recycled material):n(number of hydroxyl groups in ethylene glycol) = 2.0 and a liquid acid catalyst Sc(NTf2)3 concentration of 2.5wt% in the raw materials (methanol + ethylene glycol + recycled material), methanol, ethylene glycol, recycled material and catalyst are mixed and continuously fed into a heat exchanger to exchange heat with the etherification reaction products. Then it is fed into a preheater and heated to the reaction temperature by steam generated from the quenching steam cracking of the reaction products. Then it is fed into a batch reactor and carried out the etherification reaction under stirring at a reaction temperature of 180℃, a system pressure of 4.0MPa and a material residence time of 5.0h.

[0169] S2. Separation of etherified products: Same as step S2 in Example 47, except that the separation process is a continuous process.

[0170] S3. Purification of etherification products: Same as step S3 in Example 47, except that the purification process is a continuous process; all the ethylene glycol monomethyl ether collected by membrane separation is used as raw material for subsequent secondary etherification reaction.

[0171] S3'. Secondary etherification reaction: With a molar ratio of n(fresh methanol + methanol in the circulating material):n(total hydroxyl number of ethylene glycol + ethylene glycol monomethyl ether in the circulating material) = 2.5, n(ethylene glycol monomethyl ether):n(hydroxyl number of ethylene glycol) = 25.0, and a liquid acid catalyst Sc(NTf2)3 concentration of 2.5wt% in the feedstock (methanol + circulating material), ethylene glycol monomethyl ether collected from the permeate side of the membrane separator in step S3, a mixture containing ethylene glycol monomethyl ether, ethylene glycol, and acid catalyst collected from the bottom of the distillation column in step S2, and methanol feedstock from the acetaldehyde removal column are continuously fed into a heat exchanger to exchange heat with the secondary etherification reaction product. Then, the mixture is fed into a preheater and heated to the reaction temperature by steam generated from the quenched steam cracking reaction product. Finally, the mixture is fed into a batch reactor and carried out the etherification reaction under the conditions of stirring, reaction temperature of 200℃, system pressure of 5.0MPa, and material residence time of 3.0h. The secondary etherification reaction product is sent to the cooler in step S2.

[0172] S4. Cracking reaction and product separation: The operation process is the same as step S4 in Example 47, except that: a solid base catalyst particle Cat-6 is used, the reaction temperature is 420℃, the system pressure is 0.20MPa, and the weight hourly space velocity of ethylene glycol dimethyl ether is 0.40h. -1 .

[0173] In the above process, all the ethylene glycol monomethyl ether collected from the membrane separation in step S3 is used as raw material for the secondary etherification reaction, and 50% of the ethylene glycol dimethyl ether collected from the ethylene glycol dimethyl ether tower is used as product. After separation and recycling of the etherification, secondary etherification, and pyrolysis reaction products, the total conversion rate of ethylene glycol is 100%, the molar yields of ethylene glycol dimethyl ether and vinyl methyl ether are 51.2% and 44.3%, respectively, and the total molar yield of the two products is 95.5%.

[0174] Example 50: Preparation of vinyl methyl ether using a three-step reaction process of tubular etherification / secondary etherification and fixed-bed pyrolysis

[0175] S21. Etherification reaction: With a molar ratio of n(fresh methanol + methanol in the recycled material):n(number of hydroxyl groups in ethylene glycol) = 2.0 and a liquid acid catalyst Sm(OTf)3 concentration of 2.0 wt% in the raw materials (methanol + ethylene glycol + recycled material), methanol, ethylene glycol, recycled material and catalyst are mixed and fed into a heat exchanger to exchange heat with the etherification reaction products. Then, the mixture is continuously fed into a tubular reactor and heated by steam generated from the rapid cooling pyrolysis reaction products. The etherification reaction is carried out under the conditions of reaction temperature 180℃, system pressure 4.0 MPa and material residence time 3.0 h.

[0176] S2. Separation of etherification products: Same as step S2 in Example 47, except that the separation process is a continuous process; 50% of the material taken from the distillation column bottom is recycled back to the distillation column, and the other 50% is used as raw material for subsequent secondary etherification reaction.

[0177] S3. Purification of the etherified product: Same as step S3 in Example 47, except that the purification process is a continuous process.

[0178] S3'. Secondary etherification reaction: With a molar ratio of n(fresh methanol + methanol in the recycled material):n(total hydroxyl number of ethylene glycol + ethylene glycol monomethyl ether in the recycled material) = 2.5, n(ethylene glycol monomethyl ether):n(hydroxyl number of ethylene glycol) = 10.0, and a liquid acid catalyst Sm(OTf)3 concentration of 2.0 wt% in the raw materials (methanol + recycled material), the mixture containing ethylene glycol monomethyl ether, ethylene glycol and acid catalyst collected from the bottom of the distillation column in step S2, as well as the acetaldehyde removal column bottom liquid and methanol feed, is continuously fed into a heat exchanger to exchange heat with the secondary etherification reaction product. Then it is sent to a preheater and heated to the reaction temperature by the steam generated from the quench steam cracking reaction product in step S4. Then it is sent to a batch reactor and carried out the etherification reaction under stirring at a reaction temperature of 190℃, a system pressure of 4.5MPa and a material residence time of 4.0h. The secondary etherification reaction product is sent to the cooler in step S2.

[0179] S4. Cracking reaction and product separation: The operation process is the same as step S4 in Example 47, except that: the cracking reaction uses solid base catalyst particles Cat-2, the reaction temperature is 400℃, the system pressure is 0.40MPa, and the weight hourly space velocity of ethylene glycol dimethyl ether is 0.25h. -1 .

[0180] In the above process, 50% of the material containing ethylene glycol monomethyl ether collected from the distillation column bottom in step S2 is used as feedstock for secondary etherification, and 50% of the material collected from the distillation column top is used as product. After separation and recycling of the etherification, secondary etherification, and cracking reaction products, the total conversion rate of ethylene glycol is 100%, and the molar yields of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, and vinyl methyl ether are 44.6%, 27.2%, and 24.4%, respectively, with a total molar yield of 96.2% for the three products.

[0181] Example 51: Preparation of vinyl methyl ether using a three-step reaction process of trickle bed etherification / secondary etherification and fixed bed pyrolysis.

[0182] S1. Etherification reaction: With a molar ratio n(fresh methanol + methanol from recycled feed):n(number of hydroxyl groups in ethylene glycol) = 2.5, a mixture of methanol, ethylene glycol, recycled feed, and catalyst is fed into a heat exchanger to exchange heat with the etherification reaction products. Then, the mixture is heated to the reaction temperature using steam generated from the rapid cooling and cracking reaction products, and continuously fed into a fixed-bed reactor packed with CHPWZ solid acid catalyst particles. The reaction is carried out at a temperature of 200℃, a pressure of 5.0 MPa, and a feed weight hourly space velocity of 0.25 h⁻¹. -1 The etherification reaction is carried out under the following conditions.

[0183] S2. The separation process of the etherification product is the same as step S2 in Example 48, except that: since the catalyst CHPWZ is a solid, the coolant can be directly separated from the catalyst before being fed into the distillation column, so the material taken out of the distillation column bottom does not contain the catalyst; the material taken out of the distillation column bottom does not contain the catalyst.

[0184] S3. The purification of the etherification product is the same as step S3 in Example 48, except that all of the ethylene glycol dimethyl ether is used as a raw material for the subsequent cracking reaction.

[0185] S3'. Secondary etherification reaction: With a molar ratio of n(fresh methanol + methanol in the recycled material):n(total hydroxyl count of ethylene glycol + ethylene glycol monomethyl ether in the recycled material) = 2.5 and n(ethylene glycol monomethyl ether):n(hydroxyl count of ethylene glycol) = 25, methanol, ethylene glycol, recycled material, and catalyst are mixed and fed into a heat exchanger to exchange heat with the secondary etherification reaction products. Then, the mixture is heated to the reaction temperature using steam generated from the rapid cooling and cracking reaction products, and continuously fed into a fixed-bed reactor packed with solid acid catalyst particles HMCM-22. The reaction is carried out at a temperature of 200℃, a pressure of 5.0 MPa, and a feed weight hourly space velocity of 0.25 h⁻¹. -1A secondary etherification reaction is carried out under the conditions, and the product of the secondary etherification reaction is sent to the cooler in step S2.

[0186] S4. Cracking reaction and product separation: The operation process is the same as step S4 in Example 48, except that: the cracking reaction uses solid base catalyst particles Cat-3, the reaction temperature is 420℃, the system pressure is 0.20MPa, and the weight hourly space velocity of ethylene glycol dimethyl ether is 0.40h. -1 .

[0187] In the above process, all the ethylene glycol monomethyl ether collected from the membrane separation in step S3 is used as feedstock for secondary etherification, and all the ethylene glycol dimethyl ether collected from the top of the ethylene glycol dimethyl ether tower is used as feedstock for cracking. After separation and recycling of the etherification, secondary etherification, and cracking reaction products, the total conversion rate of ethylene glycol is 100%, and the molar yield of vinyl methyl ether is 92.8%.

[0188] Example 52: Preparation of vinyl methyl ether using a three-step reaction process of continuous batch etherification / tubular secondary etherification and fixed-bed pyrolysis.

[0189] Steps S1 to S4 were performed according to the method of Example 49, except that: the etherification and secondary etherification catalysts were both Nd(OTf)3, and the cracking reaction catalyst was Cat-1; the secondary etherification reaction was carried out in a tubular reactor.

[0190] In the above process, all the ethylene glycol monomethyl ether collected from the membrane separation in step S3 is used as raw material for the secondary etherification reaction, and 50% of the ethylene glycol dimethyl ether collected from the ethylene glycol dimethyl ether tower is used as product. After separation and recycling of the etherification, secondary etherification, and pyrolysis reaction products, the total conversion rate of ethylene glycol is 100%, the molar yields of ethylene glycol dimethyl ether and vinyl methyl ether are 48.6% and 46.2%, respectively, and the total molar yield of the two products is 94.8%.

[0191] Table 5: Reaction parameters, catalysts, and product composition for the two-step or three-step preparation of vinyl methyl ether.

[0192]

[0193] As shown in Examples 43-52 and Table 5, using ethylene glycol and methanol as raw materials, and through a two-step etherification-cracking reaction process or a three-step etherification-secondary etherification-cracking reaction process, within suitable process conditions, three products—ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, and vinyl methyl ether—can be produced in controllable proportions. It is also possible to control the production of one main product, or to co-produce two or three main products. Regardless of whether liquid acid catalyst or solid acid powder catalyst is used, and regardless of whether a batch reactor, continuous batch reactor, liquid acid catalyst, or tubular reactor is used, a one-step etherification process or a two-step etherification process is combined with a cracking reaction process using a solid base catalyst and a fixed-bed reactor, high yields of products can be obtained, with the total yield of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, and vinyl methyl ether exceeding 92.8%.

[0194] Special Note: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. Process for the preparation of vinyl methyl ether from ethylene glycol via cleavage of ethylene glycol dimethyl ether, characterized in that, The method comprises reactions shown in formula (I)-(III): HOCH2CH2OH + CH3OH → HOCH2CH2OCH3 + H2O (I); HOCH2CH2OCH3 + CH3OH → CH3OCH2CH2OCH3 + H2O (II); CH3OCH2CH2OCH3 → CH2=CHOCH3 + CH3OH (III); The catalysts for the reactions shown in formula (I) and (II) are acid catalysts, and the acid catalysts are selected from at least one of liquid acid catalysts and solid acid catalysts; The catalyst for the reaction shown in formula (III) is a base catalyst, the base catalyst is x(Ca 1.0 Mg a X b O c )-yY / zZ, wherein Ca 1.0 Mg a X b O c is the main catalyst, the auxiliary Y is selected from at least one of inorganic carbide and inorganic nitride, the carrier Z is selected from at least one of SiO2 and molecular sieve; X is a rare earth element, O is an oxygen element; x, y and z respectively represent the mass fraction of the main catalyst, the auxiliary and the carrier in the catalyst; 1.0, a, b and c respectively represent the mole ratio of Ca, Mg, X and O in the main catalyst; a=0~5, b=0~0.2; x=50~98wt%, y=2~20wt%, z=0~50wt%.

2. The method of claim 1, wherein, The molar amount of the main product obtained according to the method is more than 92.8% of the ethylene glycol raw material; wherein the main product is selected from at least one of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether and vinyl methyl ether.

3. The method of claim 1, wherein, The method comprises the following steps: S1. Etherification reaction: mixing raw materials containing ethylene glycol and methanol, and catalyzing the etherification reactions shown in formula (I) and (II) with an acid catalyst; S2. Separation of etherification products: cooling, washing and distilling the products of the etherification reaction in step S1; S3. Purification of etherification products: purifying the distillation products containing ethylene glycol dimethyl ether in step S2; and performing membrane separation on the distillation products containing ethylene glycol monomethyl ether-water azeotrope in step S2 using a membrane separator composed of multiple groups of permeation membrane assemblies; S4. Decomposition reaction and separation of its products: taking the purified distillation products containing ethylene glycol dimethyl ether in step S3 as raw materials, and catalyzing the decomposition reaction shown in formula (III) with a base catalyst; and cooling and washing the decomposition reaction products to obtain vinyl methyl ether.

4. The method of claim 3, wherein, The method comprises the following steps: S1. Etherification reaction: mixing ethylene glycol and methanol or mixing ethylene glycol, methanol and a circulating material containing ethylene glycol monomethyl ether, feeding into a preheater, heating to a reaction temperature by steam generated by quenching the decomposition reaction products, and then feeding into an etherification reactor, and catalyzing the etherification reactions shown in formula (I) and (II) with an acid catalyst; S2. Separation of etherification products: feeding the etherification products of step S1 into a cooler, cooling to below 30℃ by 4-10℃ water, feeding the gaseous material after cooling into a methanol washing tower, washing by 0-10℃ methanol, taking the by-product dimethyl ether from the gaseous phase of the methanol washing tower, and using the washing liquid as the raw material for the etherification reaction in step S1; feeding the cooling liquid into a distillation tower, flash evaporating at normal pressure, taking the mixture of methanol and ethylene glycol dimethyl ether from the top of the tower, taking the azeotrope of 14-16wt% ethylene glycol monomethyl ether-84-86wt% water from the side line of the tower, and taking the mixture containing ethylene glycol monomethyl ether and ethylene glycol from the bottom of the tower; S3. Purification of the etherification product: the mixture of methanol and ethylene glycol dimethyl ether taken from the top of the distillation column in step S2 is sent to a demethanizer column, which is subjected to atmospheric distillation, and methanol is taken from the top and recycled as raw material for the etherification reaction in step S1; the liquid taken from the bottom of the demethanizer column is sent to an ethylene glycol dimethyl ether column, which is subjected to atmospheric or reduced pressure distillation, and ethylene glycol dimethyl ether is taken from the top as raw material for the cracking reaction or partially taken as product, and the bottom material is sent back to the distillation column in step S2; the azeotrope taken from the side line of the distillation column in step S2 is treated by a membrane separator, and the retentate taken from the side line is ethylene glycol monomethyl ether, which is recycled as raw material for the etherification reaction in step S1 or partially taken as product; the material taken from the bottom of the distillation column in step S2 is recycled back to step S1 as raw material for the etherification reaction or sent to an ethylene glycol monomethyl ether rectification column, which is subjected to reduced pressure distillation, and ethylene glycol monomethyl ether is taken from the top as product, and the bottom material is recycled as raw material for the etherification reaction in step S1; S4. Cracking reaction and separation of its products: the ethylene glycol dimethyl ether taken from the ethylene glycol dimethyl ether column in step S3 is sent to a heat exchanger, heated with cracking products and then sent to a cracking reactor, in which the ethylene glycol dimethyl ether is reacted under the action of a base catalyst xCa 1.0 Mg a X b O c to generate cracking products containing vinyl methyl ether and methanol; the cracking products are sent to a heat exchanger, heated with cracking reaction raw materials and then sent to a quench tower with cooling medium being 4-10℃ water, the gas phase is taken out from the quench tower as crude vinyl methyl ether and sent to a water washing tower, the product vinyl methyl ether is taken out from the top of the water washing tower; the condensate containing methanol and a small amount of ethylene glycol dimethyl ether is recycled as the etherification reaction raw material in step S1; the steam generated by cooling the cracking products in the quench tower is sent to the preheater in step S1 to heat the etherification reaction raw materials.

5. The method of claim 3, wherein, The method further comprises a secondary etherification reaction in step S3', in which the distillation product containing ethylene glycol monomethyl ether in step S2, the membrane separation product containing ethylene glycol monomethyl ether in step S3 and / or the condensate from the quenching column containing ethylene glycol monomethyl ether in step S4 are subjected to the etherification reaction shown in formula (II) catalyzed by an acid catalyst; the reaction product containing ethylene glycol dimethyl ether obtained in the secondary etherification reaction is used as raw material for the cracking reaction in step S4.

6. The method of claim 5, wherein, The method comprises the following steps: S1. Etherification reaction: ethylene glycol is mixed with methanol or ethylene glycol, methanol and recycled material containing ethylene glycol monomethyl ether are mixed, sent to a preheater, heated to the reaction temperature by steam generated by quenching the cracking reaction product, and then sent to an etherification reactor, in which the etherification reactions shown in formula (I) and formula (II) are catalyzed by an acid catalyst; S2. Separation of the etherification product: the etherification product in step S1 is sent to a cooler, cooled to below 30°C by 4-10°C water, and the gaseous material cooled is sent to a methanol washing column, which is washed by 0-10°C methanol, and the gaseous material taken from the top of the methanol washing column is by-product dimethyl ether, and the washing liquid is used as raw material for the etherification reaction in step S1; the cooling liquid is sent to a distillation column, which is subjected to atmospheric flash distillation, and a mixture of methanol and ethylene glycol dimethyl ether is taken from the top, and an azeotrope of 14-16wt% ethylene glycol monomethyl ether and 84-86wt% water is taken from the side line, and a mixture containing ethylene glycol monomethyl ether and ethylene glycol is taken from the bottom of the column; S2. Separation of the etherification product: the etherification product in step S1 is sent to a cooler, cooled to below 30°C by 4-10°C water, and the gaseous material cooled is sent to a methanol washing column, which is washed by 0-10°C methanol, and the gaseous material taken from the top of the methanol washing column is by-product dimethyl ether, and the washing liquid is used as raw material for the etherification reaction in step S1; the cooling liquid is sent to a distillation column, which is subjected to atmospheric flash distillation, and a mixture of methanol and ethylene glycol dimethyl ether is taken from the top, and an azeotrope of 14-16wt% ethylene glycol monomethyl ether and 84-86wt% water is taken from the side line, and a mixture containing ethylene glycol monomethyl ether and ethylene glycol is taken from the bottom of the column; S3. Purification of the etherification product: the methanol and ethylene glycol dimethyl ether mixture taken from the top of the distillation column in step S2 is sent to a demethanolization column, which is operated at normal pressure and the methanol is taken from the top and recycled as raw material for the etherification reaction in step S1; the bottom product of the demethanolization column is sent to an ethylene glycol dimethyl ether column, which is operated at normal or reduced pressure and the ethylene glycol dimethyl ether is taken from the top as raw material for the cracking reaction or partially taken as product, and the bottom product is sent back to the distillation column in step S2; the azeotrope taken from the side line of the distillation column in step S2 is treated by a membrane separator, and the ethylene glycol monomethyl ether is taken from the retentate side and recycled as raw material for the secondary etherification reaction or partially taken as product; the product taken from the bottom of the distillation column in step S2 is recycled as raw material for the etherification reaction in step S1 or sent to an ethylene glycol monomethyl ether distillation column, which is operated at normal or reduced pressure and the ethylene glycol monomethyl ether is taken from the top as product, and the bottom product is recycled as raw material for the etherification reaction in step S1; S3. Secondary etherification reaction: the distillation product containing ethylene glycol monomethyl ether in step S2, the membrane separation product containing ethylene glycol monomethyl ether in step S3 and / or the condensate of the quenching column containing ethylene glycol monomethyl ether in step S4 are mixed with methanol, heated to the reaction temperature by steam generated from the quenching cracking reaction product in a preheater, and then sent to a secondary etherification reactor, in which the etherification reaction shown in formula (II) is catalyzed by an acid catalyst; the product of the secondary etherification reaction is sent to the cooler in step S2; S4. Cracking reaction and separation of its products: the ethylene glycol dimethyl ether taken from the ethylene glycol dimethyl ether column in step S3 is sent to a heat exchanger, heated with cracking products and then sent to a cracking reactor, in which the ethylene glycol dimethyl ether is reacted under the action of a base catalyst xCa 1.0 Mg a X b O c to generate cracking products containing vinyl methyl ether and methanol; the cracking products are sent to a heat exchanger, heated with cracking reaction raw materials and then sent to a quench tower with cooling medium being 4-10℃ water, the gas phase is taken out from the quench tower as crude vinyl methyl ether and sent to a water washing tower, the product vinyl methyl ether is taken out from the top of the water washing tower; the condensate containing methanol and a small amount of ethylene glycol dimethyl ether is recycled as the secondary etherification reaction raw material in step S3'; the steam generated by cooling the cracking products in the quench tower is sent to the preheaters in steps S1 and S3' to heat the etherification reaction raw materials.

7. The method according to any one of claims 3-6, characterized in that, The process of the etherification reaction in step S1 is selected from the group consisting of tank batch reaction, tank continuous reaction, tubular reaction and trickle bed reaction.

8. The method of claim 7, wherein, The conditions of the kettle type batch reaction of the etherification reaction are: temperature 100-200℃, pressure 0.5-6.0MPa, molar ratio of raw materials n(methanol):n(mono-methyl ether of ethylene glycol):n(hydroxyl number of ethylene glycol)=1.1-5.0:0-1.0:1.0, reaction time 0.5-10.0h; the conditions of the kettle type continuous reaction, tubular reaction and trickle bed reaction of the etherification reaction are: temperature 120-220℃, pressure 1.0-7.0MPa, molar ratio of raw materials n(methanol):n(mono-methyl ether of ethylene glycol):n(hydroxyl number of ethylene glycol)=1.1-5.0:0-1.0:1.0, material residence time 0.2-10.0h or feed weight hourly space velocity 0.1-5.0h -1 .

9. The method according to any one of claims 3-6, characterized in that, The step S4, the process of the cracking reaction is fixed bed reaction, the cracking reaction conditions are temperature 360~480℃, pressure 0.01~1.00MPa, ethylene glycol dimethyl ether weight hourly space velocity 0.05~2.00h -1 .

10. The method of any one of claims 3-6, wherein, In step S2, the distillation column is operated at normal pressure, the top temperature is 83-90℃, the side line temperature is 100-110℃, and the bottom temperature is 120-130℃; in step S3, the demethanolization column is operated at normal pressure, the top temperature is 65-70℃, and the bottom temperature is 80-85℃, and the ethylene glycol dimethyl ether product column is operated at a pressure of 40-60kPa, the top temperature is 68-73℃, and the bottom temperature is 80-85℃; in step S3, the ethylene glycol monomethyl ether distillation column is operated at a pressure of 10-101kPa, the top temperature is 95-125℃, and the bottom temperature is 110-140℃; In step S3, the permeation membrane is an inorganic permeation membrane, and the azeotrope taken from the side line of the distillation column is directly taken into the membrane separator in gaseous form, and the operation conditions of the membrane separation are a temperature of 100-110℃, a retentate side pressure of 0.2-0.4MPa, and a permeation side pressure of ≤2kPa; or, in step S3, the permeation membrane is an organic permeation membrane, and the azeotrope taken from the side line of the distillation column is taken into the membrane separator in liquid form after condensation, and the operation conditions are a temperature of 80-90℃, a retentate side pressure of 0.2-0.4MPa, and a permeation side pressure of ≤2kPa.

11. A catalyst x (Ca 1.0 Mg a X b O c )-yY / zZ characterized in that, Ca 1.0 Mg a X b O c Ca is a main catalyst, Y is selected from at least one of inorganic carbide and inorganic nitride, Z is selected from at least one of SiO2 and molecular sieve; X is a rare earth element, O is an oxygen element; x, y and z respectively represent the mass fraction of the main catalyst, the auxiliary agent and the carrier in the catalyst; 1.0, a, b and c respectively represent the mole ratio of Ca, Mg, X and O in the main catalyst; a=0~5, b=0~0.2; x=50~98wt%, y=2~20wt%, z=0~50wt%.

12. Use of a catalyst according to claim 11 for the preparation of vinyl methyl ether, characterized in that, The catalyst is used for catalyzing the cracking of ethylene glycol dimethyl ether to generate ethyl vinyl ether.

Images