WO2021114092A1 - 一种碳酸二甲酯的制备方法 - Google Patents

一种碳酸二甲酯的制备方法 Download PDF

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WO2021114092A1
WO2021114092A1 PCT/CN2019/124323 CN2019124323W WO2021114092A1 WO 2021114092 A1 WO2021114092 A1 WO 2021114092A1 CN 2019124323 W CN2019124323 W CN 2019124323W WO 2021114092 A1 WO2021114092 A1 WO 2021114092A1
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dimethyl carbonate
ionic liquid
preparing dimethyl
carbonate according
catalyst
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PCT/CN2019/124323
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English (en)
French (fr)
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石磊
郭建军
李新
刘铭玉
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沈阳化工大学
山东石大胜华化工集团股份有限公司
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Priority to EP19934375.7A priority Critical patent/EP3950660A4/en
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C68/00—Preparation of esters of carbonic or haloformic acids
    • C07C68/06—Preparation of esters of carbonic or haloformic acids from organic carbonates
    • C07C68/065—Preparation of esters of carbonic or haloformic acids from organic carbonates from alkylene carbonates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/063—Titanium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/08—Silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0278—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre
    • B01J31/0281—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member
    • B01J31/0282—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member of an aliphatic ring, e.g. morpholinium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0278—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre
    • B01J31/0281—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member
    • B01J31/0284—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member of an aromatic ring, e.g. pyridinium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0292—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature immobilised on a substrate
    • B01J31/0295—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature immobilised on a substrate by covalent attachment to the substrate, e.g. silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0298—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature the ionic liquids being characterised by the counter-anions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B01J37/036—Precipitation; Co-precipitation to form a gel or a cogel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2231/00—Catalytic reactions performed with catalysts classified in B01J31/00
    • B01J2231/40—Substitution reactions at carbon centres, e.g. C-C or C-X, i.e. carbon-hetero atom, cross-coupling, C-H activation or ring-opening reactions
    • B01J2231/49—Esterification or transesterification

Definitions

  • This application belongs to the chemical industry, solvent and polycarbonate industries. Specifically, it relates to a method for synthesizing a new type of strong alkaline ionic liquid and a riveting-type immobilization method of the new type of ionic liquid.
  • the prepared homogeneous and heterogeneous Phase catalyst is used for the catalytic synthesis of dimethyl carbonate.
  • Dimethyl carbonate is an important organic synthesis intermediate, which can be used to synthesize polycarbonate, carbamate, isocyanate, etc.
  • DMC is non-toxic and contains functional groups such as methyl and carbonyl groups. It can replace the highly toxic dimethyl sulfate and phosgene in the methylation reaction to synthesize many high value-added downstream products. Therefore, it is used in plastics, dyes, food additives, medicine and Pesticides and other fields have broad application prospects.
  • DMC also has a high dielectric constant and can be used in lithium-ion battery electrolytes.
  • DMC has the advantages of high oxygen content, high octane number, good gasoline/water partition coefficient, low toxicity, and rapid biodegradation. It is considered as a potential fuel oil additive. Therefore, the synthesis of dimethyl carbonate is increasingly important in the petroleum and chemical fields.
  • the currently industrialized 10,000-ton/year EC and MeOH transesterification uses sodium methoxide as a catalyst, the molar ratio of the raw materials EC and MeOH is 1:6, and the catalyst mass fraction is 0.7wt%-1.0wt% of the mixed raw materials.
  • the mixed liquid passes through the atmospheric reaction rectification tower with a bottom temperature of 72-76°C and a tower top temperature of 63.6°C.
  • the azeotrope of DMC and MeOH is extracted from the top of the rectification tower, and then high-purity DMC is obtained through high and low pressure separation.
  • Ionic liquids have the advantages of environmental protection, low saturated vapor pressure, and good thermal stability. They have good activity for the transesterification of ethylene carbonate and methanol, and are a kind of homogeneous catalysts that are promising to replace traditional catalysts.
  • the activity drops to 88%, and the yield is Decrease to 79%.
  • the above-mentioned ionic liquids all have low activity and low DMC selectivity.
  • the reported ionic liquids still have inactivation during several cycles of use.
  • the process of preparing dimethyl carbonate by catalytic distillation of ethylene carbonate and methanol needs to meet the requirements of 63.4-63.6°C to produce the azeotrope of dimethyl carbonate and methanol at the top of the tower.
  • the temperature of the bottom of the tower is maintained at about 73-75°C, and the raw materials pass through the top of the tower.
  • the time for the catalytic distillation tower to fall into the bottom of the tower is between 20-30 minutes. Therefore, it is necessary to ensure that the developed heterogeneous catalyst has high catalytic activity at 63-80°C, and the reaction equilibrium is reached within 30 minutes.
  • the current heterogeneous catalyst activity reported in the literature and patents is far lower than the demand for industrial applications.
  • a method of dimethyl carbonate is provided. Aiming at the problems of weak alkalinity, poor nucleophilicity, poor thermal stability and easy deactivation of ionic liquids reported in the literature or patents, a new type of high-temperature-resistant, high-stability strong basic ionic liquid with a special structure has been developed and Based on this type of homogeneous ionic liquid, a method for preparing a heterogeneous catalyst with a rivet embedded ionic liquid is developed.
  • the synthesized ionic liquid was reused 20 times, and its catalytic activity remained basically unchanged, showing high stability.
  • the prepared strong alkaline ionic liquid directly replaces the soluble strong bases such as sodium hydroxide or potassium hydroxide to promote the hydrolysis of single or mixed solutions such as ethyl orthosilicate, tetrabutyl titanate or aluminum metasilicate.
  • the ionic liquid is embedded with It is embedded in silicon dioxide, titanium dioxide, aluminum oxide or a single/multiple oxygen-containing compound framework with specific structure, and does not introduce Na + or K + ions at all, and the prepared heterogeneous catalyst does not need to be calcined , Can be directly applied to carbonate exchange reaction after drying/vacuum drying, showing excellent catalytic activity. Since the ionic liquid matrix has a double nitrogen ring structure, it can be embedded in the crystal lattice of -Si-O-, -Ti-O-, -Al-O- or composite oxygen-containing compounds like a double-headed climbing cone. The heterogeneous catalyst exhibits high stability, and the active components of the strong alkaline ionic liquid are not easy to lose.
  • the catalyst includes an ionic liquid
  • the ionic liquid includes anions and cations
  • Both the anion and the cation contain a nitrogen-containing heterocyclic ring.
  • the cation has a structure represented by formula I or formula II;
  • the anion has a structure shown in formula III, formula IV or formula V;
  • R 1 and R 2 are independently selected from one of C1-C6 alkane groups, C2-C6 alkenyl groups, and C3-C6 aromatic hydrocarbon groups.
  • the amount of the catalyst is 0.1%-10% of the mass of the raw material.
  • the amount of the catalyst used is 0.1% to 5% of the mass of the raw material.
  • the amount of the catalyst is 0.1% to 0.3% of the mass of the raw material.
  • the temperature of the reaction is 60-80°C.
  • the temperature of the reaction is 66-69°C.
  • the temperature of the reaction is 76-77°C.
  • the molar ratio of ethylene carbonate to ethanol in the raw material containing ethylene carbonate and methanol is 1:1 to 1:15.
  • the molar ratio of ethylene carbonate to ethanol in the raw material containing ethylene carbonate and methanol is 1:4 to 1:15.
  • the molar ratio of ethylene carbonate to ethanol in the raw material containing ethylene carbonate and methanol is 1:10 to 1:15.
  • the upper limit of the molar ratio of ethylene carbonate and ethanol in the raw material containing ethylene carbonate and methanol is selected from 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 , 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15; the lower limit is selected from 1:1, 1:2, 1:3, 1: 4. 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13 or 1:14.
  • the reaction time is 1 minute to 30 hours.
  • the chemical equilibrium is reached within 5 minutes of the reaction at 68°C.
  • the reaction reaches a chemical equilibrium at 68°C for 1 min.
  • R 1 and R 1 are independently selected from one of -CH 3 , -CH 2 CH 3 , -(CH 2 ) 2 CH 3 , and -(CH 2 ) 3 CH 3 .
  • the catalyst further includes a carrier
  • the ionic liquid is embedded in the carrier by caulking.
  • the ionic liquid is embedded in the network of the carrier.
  • the carrier and the ionic liquid have at least one of the following forces: coupling effect and hydrogen bonding effect.
  • the ratio of the weight content of the ionic liquid to the carrier in the catalyst is 0.01-0.3:0.1-0.6.
  • the carrier is selected from at least one of silicon dioxide, titanium dioxide, and aluminum oxide;
  • the ionic liquid is embedded in the network of the carrier.
  • the catalyst further includes a structural aid
  • the ionic liquid is embedded in the complex network of the structure assistant and the carrier.
  • the structural aids have divalent, trivalent or tetravalent, and together with the carrier construct the grid structure of the composite oxide, so that the environment embedded in the ionic liquid is improved, thereby enhancing the effect of the ionic liquid and the carrier composite oxide force.
  • the structural aid includes at least one of Mg, Ca, Ba, La, Ce, Zr, Fe, Zn, Li, Cs, and Al.
  • the weight content of the structure control agent in the catalyst is 10%-60%.
  • the preparation method of the ionic liquid includes the following steps:
  • the solvent in the solution I is selected from at least one of ethanol, benzene, toluene, and xylene;
  • the base is an organic base or an inorganic base
  • the organic base includes sodium methoxide, sodium ethoxide or sodium tert-butoxide, potassium methoxide, potassium ethoxide or potassium tert-butoxide;
  • the inorganic base includes sodium hydroxide or potassium hydroxide
  • the ionic liquid anion metal salt is selected from at least one of ionic liquid anion Na salt and ionic liquid anion K salt.
  • the concentration of the ionic liquid anion source in the solution I is 0.05 to 0.8 g/mL;
  • the molar ratio of the ionic liquid anion source to the base is 0.9-1.1.
  • the ionic liquid anion source includes imidazole, pyrrole or morpholine.
  • step a1) the reaction conditions are: reaction at 50-80°C for 5-12 hours.
  • step a1) further includes: after the reaction is completed, removing the solvent in the reaction system to obtain an imidazole anion salt, a pyrrole anion salt or a morpholine anion salt.
  • the solvent includes a water-carrying agent
  • the water-carrying agent is selected from at least one of ethanol, benzene, toluene, and xylene;
  • the ionic liquid cationic salt is selected from the group consisting of 1-R 1 -3-methyl-imidazole bromide, 1-R 1 -3-methyl-imidazolium bromide, N-methyl-NR 2 -morpholine bromide, N -At least one of methyl-NR 2 -morpholine iodonium salts.
  • step a2) the ratio of the ionic liquid anionic metal salt to the solvent is 0.1-0.9:0.05-1.2 g/mL.
  • step a2) the reaction conditions are: reaction at 25-80° C. for 12-48 h.
  • step a2) further includes: after the reaction is completed, removing the solvent in the reaction system to obtain the ionic liquid.
  • the preparation method of the catalyst further includes step b):
  • Water is added to the mixture containing the carrier precursor and the ionic liquid, and hydrolyzed to obtain the catalyst.
  • the carrier precursor includes at least one of ethyl orthosilicate, tetrabutyl tetrabutyl ester, aluminum isopropoxide, and sodium metaaluminate.
  • the mixture in step b) further includes a solvent
  • the weight content of the solvent in the mixture is 10% to 90%
  • the solvent includes at least one of methanol, ethanol, propanol, butanol, methyl acetate, and ethyl acetate.
  • step b)
  • the molar ratio of the carrier precursor, ionic liquid, and water is 0.2-0.8:0.03-0.4:0.1-0.4.
  • the temperature of the hydrolysis is 25-80°C.
  • the upper limit of the hydrolysis temperature is selected from 30°C, 35°C, 40°C, 50°C, 60°C, or 70°C; the lower limit is selected from 25°C, 30°C, 35°C, 40°C , 50°C or 60°C.
  • step b) after hydrolysis, the catalyst is aged between 40°C and 120°C for 6-24 hours to obtain the catalyst.
  • the mixture includes a structural aid precursor
  • the structure adjustment aid precursor includes at least one of acetate, silicate, hydrochloride, and nitrate corresponding to the structure aid.
  • step b) further includes:
  • the carrier precursor, the structural aid precursor and the solvent are mixed, the ionic liquid is added, and the mixture is uniformly mixed, and then water is added for hydrolysis to obtain the catalyst.
  • the mass ratio of the carrier precursor, structural aid precursor, solvent, ionic liquid, and water is 0.2-0.8:0.05-0.4:0.3-0.8:0.03-0.4:0.1-0.4.
  • the catalyst is a homogeneous strong base ionic liquid.
  • (1) Dissolve commercially purchased imidazole, pyrrole or morpholine in a certain amount of ethanol or benzene, toluene, xylene and other solvents, and slowly add equimolar organic or inorganic strong bases in a three-necked flask.
  • the inorganic strong bases include NaOH, KOH
  • strong organic bases include sodium methoxide, sodium ethoxide and sodium tert-butoxide, or potassium methoxide, potassium ethoxide and potassium tert-butoxide.
  • imidazole salt, pyrrole salt or morpholine salt After that, it is dried in a vacuum drying oven to a constant weight to prepare imidazole salt, pyrrole salt or morpholine salt.
  • the imidazole salt, pyrrole salt or morpholine salt obtained has Na or K cations, that is, imidazole Na or K salt, Pyrrole Na or K salt and morpholine Na or K salt.
  • the imidazole, pyrrole or morpholine ionic liquid has the following structure, the cation is 1-R-3-methyl-imidazole or N-methyl-NR-morpholine, wherein R is a normal or isomeric alkane , Olefin and aromatic structure; anion is imidazole, pyrrole or morpholine anion.
  • R -CH 3 , -CH 2 CH 3 , -(CH 2 ) 2 CH 3 and -(CH 2 ) 3 CH 3 and other alkane structures, alkenes, aromatics
  • the catalyst is a heterogeneous catalyst in which the ionic liquid is embedded in a rivet type.
  • the active components of the ionic liquid are: imidazoles, pyrroles or morpholine bases or salts, including but not limited to 1-ethyl-3-methylimidazole methoxide, 1-ethyl-3-methyl hydroxide Base imidazole base, 1-ethyl-3-methylimidazole imidazole salt, 1-ethyl-3-methylimidazole pyrrole salt, 1-ethyl-3-methylimidazoline morpholine salt, 1-butyl-3 -Methylimidazole imidazole salt, 1,3-dimethylimidazole pyrrole salt, N-methyl-N-ethylmorpholine imidazole salt, N-methyl-N-ethylmorpholine pyrrole salt, N-methyl -N-ethylmorpholine morpholine salt, N-methyl-N-butylmorpholine imidazole salt and N-methyl-N-butylmorpholine pyrrole
  • the carrier precursor includes, but is not limited to, one or several mixtures of ethyl orthosilicate, tetrabutyl tetrabutyl ester, aluminum isopropoxide, sodium metaaluminate, etc.;
  • the structure control agent contains one or more of Mg, Ca, Ba, La, Ce, Zr, Fe, Zn, Li, Cs, etc., added to the carrier in the form of acetate, silicate or other organometallic salts Precursor
  • the solvent includes, but is not limited to, one or a mixture of alcohols such as methanol, ethanol, propanol, butanol, or organic esters such as methyl acetate and ethyl acetate;
  • the carrier precursor, structure control agent and solvent are uniformly mixed, and then a certain amount of the above single or multiple ionic liquids are added, and after the mixing is uniform, 0.8-1.5 times the amount of water required by the theoretical calculation is added, and the hydrolysis temperature is controlled at 25-80°C In between, a uniform gel-like product is formed.
  • Ionic liquid not only plays the role of promoting hydrolysis, but also is the active component in the final heterogeneous catalyst.
  • the solid product is rinsed 3-5 times with the alcohol or ester solvent, in order to dissolve the ionic liquid attached to the surface. Finally, it was vacuum dried at 100-150°C for 2-6 hours to obtain a heterogeneous strong base catalyst for the caulking ionic liquid.
  • the active ionic liquid content accounts for 1%-30%
  • the carrier content accounts for 10%-60%
  • the structure control agent/structure stabilizer content is 10%-60%.
  • [EmIm]Im refers to 1-ethyl-3-methylimidazole imidazole salt.
  • [EmIm]py” refers to 1-ethyl-3-methylimidazole pyrrole salt.
  • EC means ethylene carbonate
  • DMC dimethyl carbonate
  • EG means ethylene glycol
  • HEMC refers to Intermediate 1, which means "ethylene glycol methyl carbonate”.
  • intermediate product 2 refers to "diethylene glycol carbonate”.
  • C1 to C6 refer to the number of carbon atoms contained.
  • C1-C6 alkane group refers to an alkane group containing 1 to 6 carbon atoms.
  • alkane group is a group formed by the loss of any hydrogen atom on the molecule of an alkane compound.
  • the alkane compound includes straight chain alkanes, branched chain alkanes, cycloalkanes, and branched cycloalkanes.
  • olefin group is a group formed by the loss of any hydrogen atom on the molecule of an olefin compound.
  • aromatic hydrocarbon group refers to a group formed by the loss of a hydrogen atom on the aromatic ring in the molecule of an aromatic compound; for example, a para-tolyl group formed by the loss of a hydrogen atom in the para position of the methyl group on the benzene ring of toluene.
  • the preparation method of dimethyl carbonate provided in this application aims at the problems of weak alkalinity, poor nucleophilicity or strong alkalinity ionic liquids reported in the literature or patents, such as poor thermal stability and easy inactivation. Structured high-temperature-resistant, high-stability strong basic ionic liquid and based on this kind of homogeneous ionic liquid, a method for preparing a heterogeneous catalyst with a riveting embedded ionic liquid has been developed.
  • the preparation method of dimethyl carbonate uses the prepared strong alkaline ionic liquid to directly replace the soluble strong bases such as sodium hydroxide or potassium hydroxide to promote ethyl orthosilicate, tetrabutyl titanate or Single or mixed solutions such as aluminum metasilicate are hydrolyzed, and the ionic liquid is embedded in the framework of silicon dioxide, titanium dioxide, aluminum oxide or a single/multiple oxygen-containing compound with a specific structure in a mosaic manner, and does not introduce Na+ at all Or K+ ions, the prepared heterogeneous catalyst does not need to be calcined, and can be directly applied to the carbonate exchange reaction after drying/vacuum drying, showing excellent catalytic activity.
  • the soluble strong bases such as sodium hydroxide or potassium hydroxide to promote ethyl orthosilicate, tetrabutyl titanate or Single or mixed solutions such as aluminum metasilicate are hydrolyzed
  • the ionic liquid is embedded in the framework of silicon dioxide, titanium dioxide, aluminum oxide or
  • the ionic liquid precursor has a double nitrogen ring structure, it can be embedded like a double-headed mountaineering cone -Si-O-, -Ti-O-, -Al-O- Or in the three-dimensional network of composite oxygen-containing compounds, the solid-loaded heterogeneous catalyst exhibits higher stability, and the active components of the strong alkaline ionic liquid are not easy to lose.
  • Figure 1 shows the H-NMR spectrum of the [EmIm]Im ionic liquid synthesized in Example 2.
  • Fig. 2 is the C-NMR spectrum of [EmIm]Im ionic liquid synthesized in Example 2.
  • Fig. 3 shows the H-NMR spectrum of [EmIm]py ionic liquid synthesized in Example 2.
  • Example 4 is the C spectrum of the [EmIm]py ionic liquid synthesized in Example 2.
  • Figure 5 shows the effect of different molar ratios of raw materials on the transesterification reaction of EC and MeOH.
  • Figure 6 shows the effect of reaction temperature on the transesterification of EC and MeOH.
  • Figure 7 shows the effect of the number of times the catalyst is used repeatedly on the yield of DMC.
  • Figure 8 is a 1-ethyl-3 methylimidazole imidazole ionic liquid immobilized catalyst prepared by the embedding method.
  • Figure 9 shows the infrared spectra of ionic liquid catalysts immobilized by different methods.
  • Figure 10 is the SEM image of the immobilized ionic liquid heterogeneous catalyst (Figure a is impregnated with 6g of ionic liquid catalyst; Figures b, c, and d are embedded and embedded 3g, 6g, and 12g ionic liquid catalyst, respectively).
  • nuclear magnetic H spectrum analysis nuclear magnetic C spectrum analysis, infrared spectrum analysis, SEM analysis, and XRD analysis in the examples of the present application are all routine operations, and those skilled in the art can operate according to the instructions of the instrument.
  • DMC selectivity (number of moles of DMC produced)/(number of moles of DMC produced + 1 mole of intermediate product produced + 2 moles of intermediate product produced)
  • a Reaction time is 20h.
  • Table 2 shows the data of the ionic liquid synthesized in the laboratory for the transesterification reaction of EC and MeOH.
  • the preparation method of the ionic liquid in Table 2 is the same as the preparation method of 1-ethyl-3-methylimidazole imidazole salt in Example 2. The difference The reason is that the corresponding raw materials are used.
  • Reaction conditions the molar ratio of raw material EC and MeOH is 1:10, the amount of catalyst added is 0.3wt%, and the reaction temperature is 68°C
  • reaction temperature is 68°C
  • amount of catalyst added accounts for 0.3% of the total mass of the raw materials
  • molar ratios of EC and MeOH (methanol) are 1:1, 1:4, and 1: 6, 1:10 and 1:15
  • reaction time 5min the effect of different molar ratios of raw materials on the transesterification reaction of EC and MeOH is shown in Figure 5.
  • the reaction mechanism of EC and MeOH is as follows: EC firstly opens the ring with MeOH to generate the intermediate product HEMC, and the transesterification between HEMC and MeOH generates the target product DMC.
  • N-methyl-N-ethylmorpholine morpholine salt As the catalyst, the added amount of the catalyst accounts for 0.3% of the total mass of the raw materials.
  • the change in DMC selectivity and yield with temperature and reaction time is shown in Figure 6.
  • the DMC yield was 13.87%.
  • the EC conversion rate was low at this time, the DMC selectivity was still higher than 80%.
  • the EC conversion rate increased to 40.02%, the DMC selectivity was 100%, and the DMC yield was 40.02%, indicating that N-methyl-N-ethylmorpholine morpholine salt promotes HEMC and HEMC even at low temperature. MeOH transesterification capacity is still strong.
  • the yield is basically the same as that of [Mmim]I (the mass of ionic liquid accounts for 3% of the total mass of raw materials), which has the best effect in commercialization.
  • the above data fully shows that even at 0°C, N-methyl-N- Ethylmorpholine morpholine salt ionic liquid still has high transesterification activity.
  • the DMC yield is getting higher and higher, and the DMC selectivity has been maintained at 100%, without any intermediate products being formed.
  • the yield of DMC can reach 57.04%, while reacting at 68°C (reflux temperature) for 1 minute, the yield of DMC reaches 87.24%. Continue the reaction to 5 minutes.
  • the yield of DMC is basically equivalent to the result of 1 minute, indicating that the reaction is at reflux temperature.
  • the chemical equilibrium is basically reached within 1 min.
  • the N-methyl-N-ethylmorpholine morpholine salt ionic liquid has extremely high activity, with a product selectivity of 100%, and no intermediate products and by-products are generated.
  • the yield of DMC is related to 1-ethyl-3-methylimidazole hydroxide (ie, "1-ethyl-3-methylcholine” in Figure 7) and N-methyl-N-ethylmorpholine
  • the relationship between the number of repeated uses of the pyrrole ionic liquid is shown in Figure 7.
  • the DMC yield was 80.50%, but when the catalyst was used repeatedly, the DMC yield dropped to 25.24%, which was only about a quarter of the initial activity.
  • the DMC yield continues to decline, when the catalyst is reused four times, the DMC yield is only 10.77%.
  • a method for preparing a heterogeneous silica catalyst with a single silicon dioxide hydrolyzed by tetraethyl orthosilicate as a carrier and a rivet type embedding 1-ethyl-3 methylimidazole imidazole ionic liquid Add 30 mL of ethyl orthosilicate and 21 mL of ethanol into the Erlenmeyer flask, respectively add about 12 mL of 1-ethyl-3 methylimidazole imidazole ionic liquid after heating to 60°C, and add 8.9 g of deionized water after mixing evenly.
  • the 1-ethyl-3 methylimidazole imidazole ionic liquid acts as a base to promote the hydrolysis of ethyl orthosilicate, and at the same time is the active center of the carbonate exchange reaction.
  • the system After adding deionized water, the system quickly gelled. Aging at 60°C for 12 hours, drying at 120°C for 10 hours, washing with 50 mL ethanol three times, and vacuum drying at 150°C for 3 hours to obtain a solid-supported ionic liquid catalyst.
  • the actual photo of the catalyst prepared by the riveting embedding method is shown in Figure 8. Observed from the actual photos, the surface color of the catalyst prepared by the embedded riveting method is uniform, light yellow, and the texture is crisp.
  • a fixed-bed reactor was used to evaluate the prepared heterogeneous catalyst.
  • the reaction conditions were as follows: the molar ratio of reaction raw material ethylene carbonate to methanol was 1:6, the reaction temperature was 76-77°C, the catalyst loading mass was 4g, and the reaction raw material mass The space velocity is 1h -1 , that is, the amount of raw material injected per hour is 4g, and the continuous evaluation time of each catalyst is not more than 1800min.
  • the catalyst activity of 12g 1-ethyl-3methylimidazole imidazole ionic liquid embedded at 50-70°C is shown in Table 3.
  • the catalysts prepared by hydrolysis at different temperatures all exhibit DMC selectivity higher than 90%, but the EC conversion rate of the reaction raw materials is quite different.
  • the EC conversion rate is the highest at 62.88%;
  • the EC conversion rate was only 15.80%, which was very low;
  • the EC conversion rate was in the middle, at 42.01%.
  • reaction conditions were as follows: the molar ratio of reaction raw material ethylene carbonate to methanol was 1:6, the reaction temperature was 76-77°C, the catalyst loading mass was 4g, and the reaction raw material mass The space velocity is 1h -1 , that is, the amount of raw material injected per hour is 4g, and the continuous evaluation time of each catalyst is not more than 1800min.
  • Table 4 shows the catalyst activity of different embedded ionic liquids.
  • a single silicon dioxide hydrolyzed by ethyl orthosilicate is used as a carrier, and 1,3-dimethylimidazole pyrrole salt is used as an active component to reduce the effect of the prepared catalyst on the transesterification efficiency when the active component is added.
  • the catalyst is prepared as follows: Add 30mL of ethyl orthosilicate and 21mL of ethanol into the Erlenmeyer flask, respectively add 6g of 1,3-dimethylimidazolepyrrole salt ionic liquid after heating to 60°C, add 8.9g of deionized liquid after mixing evenly Water, the system gels quickly. Aging at 60°C for 12 hours, drying at 120°C for 10 hours, washing with 50 mL ethanol three times, and drying in vacuum at 150°C for 3 hours to obtain a solid-supported catalyst.
  • silica after hydrolysis of ethyl orthosilicate as a carrier even if 6 g of 1,3-dimethylimidazole pyrrole salt ionic liquid is embedded, it exhibits an EC conversion rate of 51.55% and a DMC selectivity of 91.87%.
  • reaction conditions were as follows: the molar ratio of reaction raw material ethylene carbonate to methanol was 1:6, the reaction temperature was 76-77°C, the catalyst loading mass was 4g, and the reaction raw material mass The space velocity is 1h -1 , that is, the amount of raw material injected per hour is 4g, and the continuous evaluation time of each catalyst is not more than 1800min. Table 6 shows the catalyst activities of different embedded ionic liquids.
  • the mixed hydrolyzed oxide of ethyl orthosilicate and tetrabutyl titanate is used as a carrier to embed 1-ethyl-3-methylimidazolepyrrole salt ionic liquid.
  • 14.5mL of ethyl orthosilicate and 25mL of ethanol were added to the Erlenmeyer flask, 23mL of tetrabutyl titanate was added, and then 5.08g of zinc acetate, 4.96g of magnesium acetate and 1.89g of sodium metaaluminate were added as a structural aid, and then added to 9.35.
  • g Deionized water 14.5mL of ethyl orthosilicate and 25mL of ethanol were added to the Erlenmeyer flask, 23mL of tetrabutyl titanate was added, and then 5.08g of zinc acetate, 4.96g of magnesium acetate and 1.89g of sodium metaaluminate were added as a structural aid, and then added to
  • a fixed-bed reactor was used to evaluate the prepared heterogeneous catalyst.
  • the reaction conditions were as follows: the molar ratio of reaction raw material ethylene carbonate to methanol was 1:6, the reaction temperature was 76-77°C, the catalyst loading mass was 4g, and the reaction raw material mass The space velocity is 1h -1 , that is, the amount of raw material injected per hour is 4g, and the continuous evaluation time of each catalyst is not more than 1800min.
  • the EC conversion rate is 56.78%, and the DMC selectivity is 62.39%, which is significantly higher than that of pure tetrabutyl titanate embedded various ionic liquid catalysts to catalyze the transesterification efficiency of ethylene carbonate, and its DMC yield is tetrabutyl titanate embedded
  • the method yield is 2.25 times.
  • the apparent morphology of Figure a is a striped structure, and Figure b shows the shape of regular silica molecules.
  • the reason is that the amount of ionic liquid added is not enough to form a messy silane carrier and ionic liquid.
  • the structure of the complex The apparent morphology of the ionic liquid after embedding in Fig. c and d has undergone major changes. Disorderly small particles have gathered on the carrier, forming a complex of random silane carrier and ionic liquid, which further illustrates that the ionic liquid passes through the silane
  • the co-action is successfully loaded on the carrier, and with the increase of the load, the cluster phenomenon becomes more obvious.
  • the SEM image fully shows that the ionic liquid synthesized by the embedding method is distributed in the three-dimensional network of the dioxide through the silane group coupling effect. Among them, its microstructure is obviously different from the surface microstructure of silica.

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Abstract

本申请公开了一种碳酸二甲酯的制备方法，包括以下步骤：将含有碳酸乙烯酯和甲醇的原料，与催化剂接触，反应，得到所述碳酸二甲酯；所述催化剂包括离子液体；所述离子液体包括阴离子和阳离子；所述阳离子具有式I或式II所示的结构。该碳酸二甲酯的制备方法，开发的一系列强碱性离子液体用于碳酸乙烯酯与甲醇进行酯交换反应合成碳酸二甲酯与乙二醇，表现出极高的反应活性，即使0.3wt％含量催化剂，68-70℃反应5min即达到反应平衡，即使在0℃也具有一定的催化活性。

Description

一种碳酸二甲酯的制备方法 技术领域
本申请属于化学化工，溶剂和聚碳酸酯行业，具体而言，涉及一种新型强碱性离子液体的合成方法以及该新型离子液体嵌铆式的固载方法，所制备的均相和非均相催化剂用于碳酸二甲酯催化合成。
背景技术
碳酸二甲酯(DMC)是一种重要的有机合成中间体，可用于合成聚碳酸酯、氨基甲酸酯、异腈酸酯等。DMC无毒且结构中含有甲基、羰基等官能团，能够代替剧毒的硫酸二甲酯和光气进行甲基化反应合成许多高附加值的下游产品，因此在塑料、染料、食品添加剂、医学和农药等领域具有广泛的应用前景。DMC还具有高电介质常数，可用于锂离子电池电解液。另外DMC具有高氧含量、高辛烷值、良好的汽油/水分配系数、低毒、快速生物降解等优点，被认为是一种潜在的燃料油添加剂。因此，碳酸二甲酯的合成在石油和化工领域越来越重要。
目前，文献中报道DMC的合成方法主要有以下几种：(1)光气法：缺点是操作周期长，光气有剧毒，副产品氯化氢对设备腐蚀严重，且产品含氯高；(2)甲醇氧化羰基化法：催化剂稳定性较差且含氧副产物多；(3)甲醇二氧化碳直接合成法[18]：受热力学限制，DMC收率一般低于20％；(4)尿素醇解法：尿素极易分解为N-甲基氨基甲酸酯等副产物，且受热力学限制，DMC收率一般低于37％；(5)酯交换法：包括碳酸乙烯酯(EC)或碳酸丙烯酯(PC)与甲醇(MeOH)酯交换，两种方法均已实现工业化生产，原料价格较低，反应条件温和，工艺流程简单，对设备无腐蚀，是一种很有发展前途的生产方法。
目前已产业化的万吨级/年EC与MeOH酯交换是以甲醇钠为催化剂，原料EC和MeOH摩尔比为1:6，催化剂质量分数为混合原料的0.7wt％-1.0wt％。混合液通过常压反应精馏塔，塔釜温度72-76℃，塔顶温度63.6℃，从精馏塔顶采出DMC和MeOH共沸物，再通过高低压分离得到高纯DMC。但该过程存在一些问题：甲醇钠参与反应，对水敏感，极易失活，无法循环使用；甲醇钠失活产生的强碱性固废，从均相反应体系中分离困难，且污染环境。文献中还报道其他均相可溶强碱(如氢氧化钠或氢氧化钾)、有机铵盐、碱金属碳酸盐、离子液体等催化剂，但同样面临着催化剂失活较快，不可重复利用或重复利用次数较少等问题，限制了大规模工业应用。因此，开发一种新型高活性、高稳定性催化剂用于EC与MeOH酯交换反应是十分必要的。
离子液体(ILs)具有绿色环保、饱和蒸气压低，热稳定性好等优点，对碳酸乙烯酯与甲醇酯交换有较好的活性，是有希望代替传统催化剂的一种均相催化剂。马程明等人报道四种阳离子相同，阴离子不同的离子液体(1-丁基-3-甲基咪唑溴盐[BmIm]Br、1-丁基-3-甲基咪唑四氟硼酸盐[BmIm]BF 4、1-丁基-3-甲基咪唑碳酸氢盐[BmIm]HCO 3、1-丁基-3-甲基咪唑氢氧化物[BmIm]OH)用于EC与MeOH酯交换反应中，发现[BmIm]OH效果最好，当甲醇与碳酸乙烯酯摩尔比10:1，催化剂加入量占原料总质量的2％，67℃下反应4h，EC转化率为88.5％，DMC选择性为90.3％，但该催化剂重复使用五次后活性降至76.9％；Hye-Young Ju等人报道了以1-乙基-3-甲基咪唑氯盐EMImCl为催化剂，在反应温度160℃、催化剂加入0.89wt％，反应6h时，EC转化率为80.4％，DMC选择性为97.6％；Zhenzhen Yang合成阳离子为1,4-二氮杂二环辛烷的离子液体，发现当阴离子为OH-时的催化活性和稳定性综合最佳，反应温度70℃，催化剂含量1mol％，反应时间6h，EC转化率为90％，DMC收率为81％，催化剂重复使用四次后活性降为88％，收率降为79％。与甲醇钠相比(反应5min即达到平衡转化率)，上述离子液体均存在活性低，DMC选择性低。并且报道的离子液体在数次循环使用过程中仍存在失活现象。碳酸乙烯酯与甲醇催化精馏制备碳酸二甲酯工艺需满足塔顶63.4-63.6℃采出碳酸二甲酯与甲醇共沸物，塔釜温度保持在73-75℃左右，原料从塔顶经催化精馏塔落入塔釜时间在20-30min之间，因此需保证开发的非均相催化剂在63-80℃之间具有高催化活性，反应30min之内达到反应平衡。而目前文献和专利报道的非均相催化剂活性远低于工业应用的需求。
发明内容
根据本申请的一个方面，提供了一种碳酸二甲酯的方法。针对文献或专利报道的离子液体碱性弱、亲核性差或强碱性离子液体热稳定性差、容易失活等问题，开发新型具有特殊结构的耐高温、高稳定性的强碱性离子液体以及基于该类均相离子液体，开发嵌铆式包埋离子液体制备非均相催化剂的方法。开发的一系列强碱性离子液体用于碳酸乙烯酯与甲醇进行酯交换反应合成碳酸二甲酯与乙二醇，表现出极高的反应活性，即使0.3wt％含量催化剂，68-70℃反应5min即达到反应平衡，即使在0℃也具有一定的催化活性。合成的离子液体重复使用20次，其催化活性基本不变，表现出较高的稳定性。采用制备的强碱性离子液体直接代替氢氧化钠或氢氧化钾等可溶强碱促进正硅酸乙酯、 钛酸四丁酯或偏硅酸铝等单一或混合溶液水解，离子液体以镶嵌的方式包埋在二氧化硅、二氧化钛、三氧化二铝或具有特定结构的单一/多种含氧化合物骨架中，且完全不引入Na +或K +离子，所制备的非均相催化剂无需焙烧，可直接经干燥/真空干燥后应用于碳酸酯交换反应，展现出极佳的催化活性。由于离子液体母体具有双氮环结构，可以像双头登山锥一样嵌入-Si-O-、-Ti-O-、-Al-O-或复合含氧化合物的晶格中，因此固载后的非均相催化剂表现出较高的稳定性，强碱性离子液体活性组分不易流失。
所述碳酸二甲酯的制备方法，其特征在于，包括以下步骤：
将含有碳酸乙烯酯和甲醇的原料，与催化剂接触，反应，得到所述碳酸二甲酯；
所述催化剂包括离子液体；
所述离子液体包括阴离子和阳离子；
所述阴离子和阳离子均含有含氮杂环。
可选地，所述阳离子具有式I或式II所示的结构；
Figure PCTCN2019124323-appb-000001
所述阴离子具有式III、式IV或式V所示的结构；
Figure PCTCN2019124323-appb-000002
其中，R 1、R 2独立地选自C1-C6的烷烃基、C2-C6的烯烃基、C3-C6的芳烃基中的一种。
可选地，所述催化剂的用量为原料质量的0.1％～10％。
可选地，所述催化剂的用量为原料质量的0.1％～5％。
所述催化剂的用量为原料质量的0.1％～0.3％。
可选地，所述反应的温度为60～80℃。
可选地，所述反应的温度为66～69℃。
可选地，所述反应的温度为76～77℃。
可选地，所述含有碳酸乙烯酯和甲醇的原料中碳酸乙烯酯和乙醇的摩尔比为1:1～1:15。
可选地，所述含有碳酸乙烯酯和甲醇的原料中碳酸乙烯酯和乙醇的摩尔比为1:4～1:15。
可选地，所述含有碳酸乙烯酯和甲醇的原料中碳酸乙烯酯和乙醇的摩尔比为1:10～1:15。
可选地，所述含有碳酸乙烯酯和甲醇的原料中碳酸乙烯酯和乙醇的摩尔比的上限选自1:2、1:3、1:4、1:5、1:6、1:7、1:8、1:9、1:10、1:11、1:12、1:13、1:14或1:15；下限选自1:1、1:2、1:3、1:4、1:5、1:6、1:7、1:8、1:9、1:10、1:11、1:12、1:13或1:14。可选地，所述反应的时间为1分钟～30小时。
可选地，68℃下，反应5min以内达到化学平衡。
可选地，68℃下，反应1min达到化学平衡。
可选地，R 1、R 1独立地选自-CH 3、-CH 2CH 3、-(CH 2) 2CH 3、-(CH 2) 3CH 3中的一种。
可选地，所述催化剂还包括载体；
所述离子液体嵌铆式包埋在所述载体中。
可选地，所述离子液体嵌入所述载体的网络中。
可选地，所述载体与所述离子液体存在以下作用力中的至少一种：偶联作用、氢键作用。
可选地，所述催化剂中离子液体与载体重量含量的比例为0.01～0.3：0.1～0.6。
可选地，所述载体选自二氧化硅、二氧化钛、三氧化二铝中的至少一种；
所述载体形成的同时，所述离子液体嵌入所述载体的网络中。
可选地，所述催化剂中还包括结构助剂；
所述离子液体嵌入所述结构助剂与所述载体复合的网络中。所述结构助剂分别具有2价、3价或者4价，与载 体共同构建复合氧化物的网格结构，使离子液体所包埋的环境得到改善，进而增强离子液体与载体复合氧化物的作用力。
可选地，所述结构助剂包括Mg、Ca、Ba、La、Ce、Zr、Fe、Zn、Li、Cs、Al中的至少一种。
可选地，所述结构调控剂在所述催化剂中的重量含量为10％～60％。
可选地，所述离子液体的制备方法包括以下步骤：
a1)向含有离子液体阴离子源的溶液I中，加入碱，反应，得到离子液体阴离子金属盐；
a2)将所述离子液体阴离子金属盐溶解在溶剂中，加入离子液体阳离子盐，反应，得到所述离子液体。
可选地，步骤a1)中，所述溶液I中的溶剂选自乙醇、苯、甲苯、二甲苯中的至少一种；
所述碱为有机碱或无机碱；
所述有机碱包括甲醇钠、乙醇钠或叔丁醇钠、甲醇钾、乙醇钾或叔丁醇钾；
所述无机碱包括氢氧化钠或氢氧化钾；
所述离子液体阴离子金属盐选自离子液体阴离子Na盐、离子液体阴离子K盐中的至少一种。
可选地，步骤a1)中，所述溶液I中，离子液体阴离子源的浓度为0.05～0.8g/mL；
所述离子液体阴离子源与所述碱的摩尔比为0.9～1.1。
可选地，步骤a1)中，所述离子液体阴离子源包括咪唑、吡咯或者吗啉。
可选地，步骤a1)中，所述反应的条件为：50～80℃下反应5～12小时。
可选地，步骤a1)还包括：反应结束后，除去反应体系中的溶剂，得到咪唑阴离子盐、吡咯阴离子盐或者吗啉阴离子盐。
可选地，步骤a2)中，所述溶剂包括带水剂；
所述带水剂选自乙醇、苯、甲苯、二甲苯中的至少一种；
所述离子液体阳离子盐选自1-R 1-3-甲基-咪唑溴盐、1-R 1-3-甲基-咪唑碘盐、N-甲基-N-R 2-吗啉溴盐、N-甲基-N-R 2-吗啉碘盐中的至少一种。
可选地，步骤a2)中，所述离子液体阴离子金属盐与溶剂的比例为0.1～0.9：0.05～1.2g/mL。
可选地，步骤a2)中，所述反应的条件为：25～80℃下反应12～48h。
可选地，步骤a2)还包括：反应结束后，除去反应体系中的溶剂，得到所述离子液体。
可选地，所述催化剂的制备方法还包括步骤b)：
将水加入到含有载体前驱体和离子液体的混合物中，水解，得到所述催化剂。
可选地，步骤b)中，所述载体前驱体包括正硅酸乙酯、太酸四丁酯、异丙醇铝、偏铝酸钠中的至少一种。
可选地，步骤b)中所述混合物中还包括溶剂；
所述溶剂在所述混合物中的重量含量为10％～90％；
所述溶剂包括甲醇、乙醇、丙醇、丁醇、乙酸甲酯、乙酸乙酯中的至少一种。
可选地，步骤b)中，
所述载体前驱体、离子液体、水的摩尔比为0.2～0.8：0.03～0.4：0.1～0.4。
可选地，步骤b)中，所述水解的温度为25～80℃。
可选地，步骤b)中，所述水解的温度的上限选自30℃、35℃、40℃、50℃、60℃或70℃；下限选自25℃、30℃、35℃、40℃、50℃或60℃。
可选地，步骤b)中，水解后，40～120℃之间老化6～24小时，得到所述催化剂。
可选地，步骤b)，所述混合物中包括结构助剂前驱体；
所述结构调助剂前驱体包括结构助剂相应的醋酸盐、硅酸盐、盐酸盐、硝酸盐中的至少一种。
可选地，步骤b)还包括：
将载体前驱体、结构助剂前驱体与溶剂混合，加入离子液体，混合均匀，然后加入水，进行水解，得到所述催化剂。
可选地，步骤b)，所述载体前驱体、结构助剂前驱体、溶剂、离子液体、水的质量比为0.2～0.8:0.05～0.4：0.3～0.8：0.03～0.4：0.1～0.4。
作为一种实施方式，所述催化剂为均相强碱离子液体。
所述的均相强碱性离子液体催化剂制备方法：
(1)将商业购买的咪唑、吡咯或吗啉溶于一定量乙醇或苯、甲苯、二甲苯等溶剂中，在三口烧瓶中缓慢加入 等摩尔的有机或无机强碱，无机强碱包括NaOH，KOH，有机强碱包括甲醇钠、乙醇钠以及叔丁醇钠等，或甲醇钾、乙醇钾以及叔丁醇钾等。在50-80℃条件下剧烈搅拌5-12h，反应结束后，在油锅60-120℃条件下，减压旋蒸出去溶剂以及反应生成醇类或水。之后，放入真空干燥箱烘干至恒重，制备得到咪唑盐、吡咯盐或吗啉盐，得到的咪唑盐、吡咯盐或吗啉盐具有Na或K的阳离子，即咪唑Na或K盐、吡咯Na或K盐以及吗啉Na或K盐。
(2)将一定量的具有Na或K的阳离子咪唑盐、吡咯盐或吗啉盐溶于一定量乙醇或苯、甲苯、二甲苯等带水剂溶剂中，在三口烧瓶中加入等摩尔的商业购买的1-R-3-甲基-咪唑溴/碘盐或N-甲基-N-R-吗啉溴/碘盐离子液体进行阳离子反应，在25-80℃条件下剧烈搅拌反应12-48h，得到Na/KBr或Na/KI沉淀以及目标离子液体。
(3)将含有目标离子液体的混合物经过多次过滤后，在油锅65-100℃条件下，进行减压旋蒸除去溶剂，旋蒸1-4h后，将其置于真空干燥箱烘干至恒重，得纯组分的目标产物。
所述的咪唑类、吡咯或吗啉类离子液体具有如下结构，阳离子为1-R-3-甲基-咪唑或N-甲基-N-R-吗啉，其中R为正构或者异构的烷烃、烯烃以及芳烃结构；阴离子为咪唑、吡咯或吗啉负离子。
Figure PCTCN2019124323-appb-000003
R＝-CH 3、-CH 2CH 3、-(CH 2) 2CH 3以及-(CH 2) 3CH 3等烷烃结构、烯烃、芳烃
作为一种实施方式，所述催化剂为嵌铆式包埋离子液体的非均相催化剂。所述的嵌铆式包埋离子液体制备非均相催化剂的方法：
所述的离子液体活性组分为：咪唑类、吡咯类或吗啉类碱或盐，包括但不限于1-乙基-3-甲基咪唑甲醇盐、氢氧化1-乙基-3-甲基咪唑碱、1-乙基-3-甲基咪唑咪唑盐、1-乙基-3-甲基咪唑吡咯盐、1-乙基-3-甲基咪唑吗啉盐、1-丁基-3-甲基咪唑咪唑盐、1,3-二甲基咪唑吡咯盐、N-甲基-N-乙基吗啉咪唑盐、N-甲基-N-乙基吗啉吡咯盐、N-甲基-N-乙基吗啉吗啉盐、N-甲基-N-丁基吗啉咪唑盐以及N-甲基-N-丁基吗啉吡咯盐等离子液体。
所述的载体前驱体包括并不限于正硅酸乙酯、太酸四丁酯、异丙醇铝、偏铝酸钠等一种或几种混合物；
所述的结构调控剂含有Mg、Ca、Ba、La、Ce、Zr、Fe、Zn、Li、Cs等一种或多种以醋酸盐、硅酸盐或其他有机金属盐的形式加入到载体前驱体中；
所述的溶剂包括但不限于甲醇、乙醇、丙醇、丁醇等醇类或乙酸甲酯、乙酸乙酯等有机酯类中一种或几种混合物；
载体前驱体、结构调控剂与溶剂均匀混合，而后加入一定量的上述单一或多种离子液体，混合均匀后加入理论计算所需水量的0.8-1.5倍的水，水解温度控制在25-80℃之间，形成均匀的凝胶类产物。离子液体既起到促进水解的作用，又是最终非均相催化剂中的活性组分。在40-120℃之间老化6-24后，采用所述醇类或酯类的溶剂对固态产物进行3-5次漂洗，目的是溶解表面附着的离子液体。最后100-150℃真空干燥2-6h，得到嵌铆离子液体的非均相强碱催化剂。
所述的非均相催化剂中活性离子液体含量占1％-30％，载体含量占10％-60％，结构调控剂/结构稳定剂含量10％-60％。
本申请中，“[EmIm]Im”指1-乙基-3-甲基咪唑咪唑盐。
本申请中，“[EmIm]py”指1-乙基-3-甲基咪唑吡咯盐。
本申请中，“EC”指碳酸乙烯酯。
本申请中，“DMC”指碳酸二甲酯。
本申请中，“EG”为乙二醇。
本申请中，“HEMC”即为中间产物1，是指“碳酸甲醇乙二醇酯”。
本申请中，“中间产物2”是指“碳酸二乙二醇酯”。
本申请中，C1～C6指所包含的碳原子数。如“C1～C6的烷烃基”指含有碳原子数为1～6的烷烃基。
本申请中，“烷烃基”是由烷烃化合物分子上失去任意一个氢原子所形成的基团。所述烷烃化合物包括直链烷烃、支链烷烃、环烷烃、带有支链的环烷烃。
本申请中，“烯烃基”是由烯烃化合物分子上失去任意一个氢原子所形成的基团。
本申请中，“芳烃基”是芳香族化合物分子上失去芳香环上一个氢原子所形成的基团；如甲苯失去苯环上甲基对位的氢原子所形成的对甲苯基。
本申请能产生的有益效果包括：
1)本申请所提供的碳酸二甲酯的制备方法，针对文献或专利报道的离子液体碱性弱、亲核性差或强碱性离子液体热稳定性差、容易失活等问题，开发新型具有特殊结构的耐高温、高稳定性的强碱性离子液体以及基于该类均相离子液体，开发嵌铆式包埋离子液体制备非均相催化剂的方法。
2)本申请所提供的碳酸二甲酯的制备方法，开发的一系列强碱性离子液体用于碳酸乙烯酯与甲醇进行酯交换反应合成碳酸二甲酯与乙二醇，表现出极高的反应活性，即使0.3wt％含量催化剂，68-70℃反应5min即达到反应平衡，即使在0℃也具有一定的催化活性。
3)本申请所提供的碳酸二甲酯的制备方法，采用制备的强碱性离子液体直接代替氢氧化钠或氢氧化钾等可溶强碱促进正硅酸乙酯、钛酸四丁酯或偏硅酸铝等单一或混合溶液水解，离子液体以镶嵌的方式包埋在二氧化硅、二氧化钛、三氧化二铝或具有特定结构的单一/多种含氧化合物骨架中，且完全不引入Na+或K+离子，所制备的非均相催化剂无需焙烧，可直接经干燥/真空干燥后应用于碳酸酯交换反应，展现出极佳的催化活性。
4)本申请所提供的碳酸二甲酯的制备方法，由于离子液体母体具有双氮环结构，可以像双头登山锥一样嵌入-Si-O-、-Ti-O-、-Al-O-或复合含氧化合物的三维网络中，因此固载后的非均相催化剂表现出较高的稳定性，强碱性离子液体活性组分不易流失。
附图说明
图1为实施例2合成的[EmIm]Im离子液体核磁H谱。
图2为实施例2合成的[EmIm]Im离子液体核磁C谱。
图3为实施例2合成的[EmIm]py离子液体核磁H谱。
图4为实施例2合成的[EmIm]py离子液体核磁C谱。
图5为不同原料摩尔比对EC和MeOH酯交换反应的影响。
图6为反应温度对EC和MeOH酯交换反应的影响。
图7为催化剂重复使用次数对DMC收率的影响。
图8为采用包埋法制备的1-乙基-3甲基咪唑咪唑离子液体固载催化剂。
图9为不同方法固载的离子液体催化剂红外谱图。
图10为固载离子液体非均相催化剂SEM图(图a浸渍6g离子液体催化剂；图b、c、d分别为嵌入包埋3g、6g、12g离子液体催化剂)。
具体实施方式
下面结合实施例详述本申请，但本申请并不局限于这些实施例。
如无特别说明，本申请的实施例中的原料和催化剂均通过商业途径购买。
本申请的实施例中核磁H谱分析、核磁C谱分析、红外光谱分析、SEM分析、XRD分析均为常规操作，本领域技术人员根据仪器说明操作即可。
本申请的实施例中转化率、选择性计算如下：
本申请的实施例中，转化率以及选择性都基于碳摩尔数进行计算：
EC转化率＝(生成的DMC摩尔数+生成的中间产物1摩尔数+生成的中间产物2摩尔数)/(生成的DMC摩尔数+生成的中间产物1摩尔数+生成的中间产物2摩尔数+未反应的EC摩尔数)
实施例中没有涉及甲醇的转化率
DMC选择性＝(生成的DMC摩尔数)/(生成的DMC摩尔数+生成的中间产物1摩尔数+生成的中间产物2摩尔数)
EG选择性＝(生成的EG摩尔数)/(生成的DMC摩尔数+生成的中间产物1摩尔数+生成的中间产物2摩尔数)
DMC收率＝(DMC转化率)*(DMC选择性)*100％
实施例1
选取一系列典型、已商业化的离子液体，研究了酸性离子液体1-乙基-3-甲基咪唑硫酸乙酯盐([Emim]C 2H 5SO 4)、1-乙基-3-甲基咪唑六氟锑酯盐([Emim]SbF 6)、1-乙基-3-甲基咪唑对甲基苯磺酸盐([Emim]ToS)、1-丁基-3-甲基咪唑四氟硼酸盐([Bmim]BF 4)、1-乙基-3-甲基咪唑四氟硼酸盐([Emim]BF 4)、1-丁基-3-甲基咪唑六氟磷酸盐([Bmim]PF 6)、1-乙基-3-甲基咪唑六氟磷酸盐([Emim]PF 6)、1-丁基-3-甲基咪唑氯盐([Bmim]Cl)、1-乙基-3-甲基咪唑氯盐([Emim]Cl)、1，3-二甲基咪唑氯盐([Mmim]Cl)、1-丁基-3-甲基咪唑溴盐([Bmim]Br)、1-乙基-3-甲基咪唑溴盐([Emim]Br)、1-丁基-3-甲基咪唑碘盐([Bmim]I)以及1-乙基-3-甲基咪唑碘盐([Emim]I)、1，3-二甲基咪唑碘盐([Mmim]I)对碳酸乙烯酯(EC)与甲醇(MeOH)酯交换反应的影响，结果如表1所示。反应条件：EC:MeOH＝1:10，反应温度68℃，催化剂含量3wt％，反应时间2h。
表1商业离子液体对EC与MeOH酯交换反应的影响
Figure PCTCN2019124323-appb-000004
a反应时间20h。
由表1可以看出：常规商业催化剂活性均不高，最优离子液体[Mmim]I含量占反应原料质量3％，反应时间2h，仅达到61.91％EC转化率以及67.47％的DMC选择性，DMC收率仅为41.77％。
实施例2
1-乙基-3-甲基咪唑咪唑盐具体制备方法：将0.5mol的咪唑溶于60mL乙醇溶剂中，在三口烧瓶中加入等摩尔的乙醇钾，在60℃条件下剧烈搅拌6h，反应结束后，在油浴锅65℃条件下，减压旋蒸2h除去溶剂乙醇和产物乙醇，放入真空干燥箱烘干12h至恒重，制备得到咪唑钾盐。在三口烧瓶中加入0.5mol的商业购买的[EmIm]Br，在乙醇带水剂作溶剂的条件下，加入等摩尔比的咪唑钾，在室温条件下搅拌反应24h。反应结束之后，过滤除去生成的白色固体KBr，在油浴锅65℃条件下，减压旋蒸2h除去溶剂，置于真空干燥箱烘干12h至恒重，得淡黄色粘稠状液体[EmIm]Im，其核磁谱图如图1和图2所示。图1合成的[EmIm]Im离子液体核磁H谱：[EmIm]Im 1H NMR(500MHz,DMSO-d6)δ(ppm):8.61(d,J＝1.9Hz,1H,NCHN),7.75(d,J＝1.9Hz,1H,NCH),7.58(s,1H,NCH),6.23(s,2H,NCHCHN),4.17(q,J＝7.3Hz,2H,NCH 2CH 3),3.83(s,3H,NCH 3),1.37(t,J＝7.3Hz,3H,NCH 2CH 3)。图2合成的 [EmIm]Im离子液体核磁C谱： 13C NMR(126MHz,DMSO-d6)δ(ppm):166.43(s),136.99(s),136.18(s),123.97(s),122.39(s),122.31(s),44.51(s),36.06(s),15.56(s)。因此，合成的离子液体确定为1-乙基-3-甲基咪唑咪唑盐。
1-乙基-3-甲基咪唑吡咯盐具体制备方法：将0.5mol的吡咯溶于60mL乙醇溶剂中，在三口烧瓶中加入等摩尔的乙醇钾，在70℃条件下剧烈搅拌6h，反应结束后，在油浴锅65℃条件下，减压旋蒸2h除去溶剂乙醇和产物乙醇，放入真空干燥箱烘干至恒重12h，制备得到吡咯钾盐。在三口烧瓶中加入0.5mol的商业购买的[EmIm]Br，在乙醇带水剂作溶剂的条件下，加入等摩尔比的吡咯钾，在室温下搅拌反应24h。反应结束之后，过滤除去生成的白色固体KBr，在油浴锅65℃条件下，减压旋蒸2h除去溶剂，置于真空干燥箱烘干至恒重12h，得淡黄色粘稠状液体[EmIm]py，其核磁谱图如图3和图4所示。图3合成的[EmIm]py离子液体核磁H谱：[EmIm]Py 1H NMR(500MHz,DMSO-d 6)δ(ppm):9.30(s,1H,NCHN),7.84(s,1H,NCHCHN),7.74(s,1H,NCHCHN),6.74(d,J＝1.9Hz,2H,NCHCH),6.02(d,J＝1.5Hz,2H,CHCHCH),4.20(q,J＝7.3Hz,2H,NCH 2CH 3),3.85(s,3H,NCH 3),1.39(t,J＝7.3Hz,3H,NCH 2CH 3)。图4合成的[EmIm]py离子液体核磁C谱： 13C NMR(126MHz,DMSO-d 6)δ(ppm)136.71(s),123.96(s),122.41(s),117.79(s),107.56(s),44.56(s),36.20(s),15.63(s)。因此，合成的离子液体确定为1-乙基-3-甲基咪唑吡咯盐。
实施例3
表2为实验室合成的离子液体用于EC和MeOH酯交换反应的数据，表2中离子液体的制备方法同实施例2中1-乙基-3-甲基咪唑咪唑盐的制备方法，区别在于采用了相应的原料。催化剂评价条件为反应温度68℃，反应时间5min，原料摩尔比EC:MeOH＝1:10，催化剂含量为原料质量分数的0.3％。
表2合成的离子液体对EC与MeOH酯交换反应活性的影响
Figure PCTCN2019124323-appb-000005
反应条件：原料EC和MeOH摩尔比1:10，催化剂加入量0.3wt％，反应温度68℃
从表1中的数据可知，强碱性离子液体均表现出优异的催化活性，DMC和EG选择性均达到100％，除1-乙基-3-甲基咪唑甲醇盐和氢氧化1-乙基-3-甲基咪唑碱以外，其余离子液体均接近该反应条件下的平衡转化率89％左右。
实施例4
以1,3-二甲基咪唑吡咯盐为催化剂，反应温度68℃，催化剂加入量占原料总质量的0.3％，EC与MeOH(甲醇)摩尔分别比为1:1，1:4，1:6，1:10以及1:15，反应时间5min，不同原料摩尔比对EC与MeOH酯交换反应的影响如图5所示。EC与MeOH反应机理为：EC首先与MeOH开环生成中间产物HEMC，HEMC与MeOH酯交换生成目标产物DMC。但采用强碱性催化剂1,3-二甲基咪唑吡咯盐时，即使MeOH含量很低(EC:MeOH＝1:1)，DMC收率仅为9.63％时，仍然没有检测到中间产物HEMC以及其他副产物的生成，说明EC与MeOH酯交换过程中，EC开环为速率控制步骤；在反应温度下，HEMC(中间产物1，碳酸甲醇乙二醇酯)与MeOH酯交换生成DMC不受热力学平衡限制。当EC:MeOH＝1:4时，DMC收率迅速增加至63.33％，继续提高MeOH含量，DMC收率持续增加，当EC:MeOH＝1:10时，DMC收率高达90.28％，进一步增加MeOH与EC摩尔比至1:15时，DMC收率提 升至92.81％，但增加幅度较小。EC与MeOH酯交换反应为可逆过程，增加原料MeOH比例可以促进EC的转化，使得反应向正反应方向进行，DMC收率增加。
实施例5
以N-甲基-N-乙基吗啉吗啉盐为催化剂，催化剂加入量占原料总质量的0.3％，DMC选择性和收率随温度和反应时间变化如图6所示。0℃反应5min时，DMC收率为13.87％，虽然此时EC转化率较低，但DMC选择性仍高于80％。0℃反应120min时，EC转化率提升至40.02％，DMC选择性为100％，DMC收率为40.02％，说明N-甲基-N-乙基吗啉吗啉盐即使在低温下促进HEMC与MeOH酯交换能力仍较强。收率与目前已商业化中效果最好的[Mmim]I(离子液体质量占原料总质量的3％)相比基本相当，以上数据充分说明即使在0℃下，N-甲基-N-乙基吗啉吗啉盐离子液体仍具有较高的酯交换活性。逐渐升高反应温度，DMC收率越来越高，并且DMC选择性一直保持100％，无任何中间产物生成。50℃反应5min，DMC收率可以达到57.04％，而68℃(回流温度)反应1min，DMC收率达到87.24％，继续反应至5min，DMC收率与1min结果基本相当，表明在回流温度下反应1min即基本达到化学平衡，N-甲基-N-乙基吗啉吗啉盐离子液体活性极高，产物选择性100％，完全没有中间产物和副产物生成。
实施例6
分别以氢氧化1-乙基-3-甲基咪唑碱和N-甲基-N-乙基吗啉吡咯盐为催化剂，考察其稳定性。0.3wt％离子液体，EC:MeOH(摩尔比)＝1:10，68℃反应5min后停止反应并取样分析，之后150-155℃，-0.1MPa减压旋蒸120min，回收剩余离子液体进行下一次循环。DMC收率与氢氧化1-乙基-3-甲基咪唑碱(即为图7中的“1-乙基-3-甲基胆碱”)和N-甲基-N-乙基吗啉吡咯离子液体重复使用次数的关系如图7所示。1-乙基-3-甲基咪唑碱初次使用时，DMC收率为80.50％，但当催化剂重复使用一次时，DMC收率骤降至25.24％，仅为初始活性的四分之一左右。继续增加重复使用次数，DMC收率持续下降，当催化剂重复使用四次时，DMC收率仅为10.77％。以上结果充分说明，[Emim]OH稳定性较差，仅能够使用一次，失活较快。而合成的N-甲基-N-乙基吗啉吡咯离子液子重复使用20次，DMC收率一直维持在88％-90％，DMC选择性100％，无失活现象发生，在催化剂质量仅为0.3wt％情况下都展现出极佳的稳定性。可见N-甲基-N-乙基吗啉吡咯既具有良好的低温催化活性，100％产物选择性，又具有极好的热稳定性，重复使用性能。
实施例7
以单一的正硅酸乙酯水解后的二氧化硅为载体，嵌铆式包埋1-乙基-3甲基咪唑咪唑离子液体的二氧化硅非均相催化剂的制备方法。将30mL正硅酸乙酯和21mL乙醇分别加入锥形瓶，加热到60℃后分别立即加入约12mL的1-乙基-3甲基咪唑咪唑离子液体，混合均匀后加入8.9g去离子水。其中1-乙基-3甲基咪唑咪唑离子液体起到碱催化的作用促进正硅酸乙酯水解，同时又是碳酸酯交换反应的活性中心。加入去离子水后，体系迅速凝胶。60℃温度下老化12h，120℃干燥10h后用50mL乙醇洗涤三次，150℃真空干燥3h即得固载后的离子液体催化剂。采用嵌铆式包埋法制备的催化剂实物照片如图8所示。从实物照片观察，嵌铆式包埋法制备的催化剂外表颜色均一，为淡黄色，质地松脆。
实施例8
采用固定床反应器对制备的非均相催化剂进行评价，反应条件为：反应原料碳酸乙烯酯与甲醇摩尔比为1:6，反应温度76-77℃，催化剂装填质量为4g，反应原料的质量空速为1h -1，即原料每小时进样量为4g，每个催化剂连续评价时间为不超过1800min。50-70℃包埋12g的1-乙基-3甲基咪唑咪唑离子液体催化剂活性如表3所示。以SiO 2为包埋载体，不同温度下水解制备的催化剂均展现出高于90％的DMC选择性，但反应原料EC转化率差别较大，60℃水解时，EC转化率最高为62.88％；但70℃水解时，EC转化率仅为15.80％，非常低；50℃水解时，EC转化率居中，为42.01％。
表3不同水解温度固载的离子液体催化剂对EC和MeOH反应的影响
Figure PCTCN2019124323-appb-000006
Figure PCTCN2019124323-appb-000007
EC/MeOH＝1/6，包埋量12g，反应温度76-77℃，催化剂装填4g，质量空速1h -1，反应1800min
实施例9
以单一的正硅酸乙酯水解后的二氧化硅为载体，60℃水解分别嵌铆式包埋12g 1-乙基-3-甲基咪唑吡咯盐、1-乙基-3-甲基咪唑吗啉盐、1-丁基-3-甲基咪唑咪唑盐、1,3-二甲基咪唑吡咯盐、N-甲基-N-乙基吗啉吗啉盐以及N-甲基-N-丁基吗啉吡咯盐。采用固定床反应器对制备的非均相催化剂进行评价，反应条件为：反应原料碳酸乙烯酯与甲醇摩尔比为1:6，反应温度76-77℃，催化剂装填质量为4g，反应原料的质量空速为1h -1，即原料每小时进样量为4g，每个催化剂连续评价时间为不超过1800min。不同嵌入包埋的离子液体催化剂活性如表4所示。
表4嵌入包埋不同离子液体催化剂对EC和MeOH反应的影响
Figure PCTCN2019124323-appb-000008
EC/MeOH＝1/6，包埋量12g，反应温度76-77℃，催化剂装填4g，质量空速1h -1，反应1800min
以单一的正硅酸乙酯水解后的二氧化硅为载体，嵌入包埋不同类别的离子液体均展现出优异的EC和MeOH酯交换能力，EC转化率均达到60％以上，DMC选择性达到93％以上。其中1,3-二甲基咪唑吡咯盐展现出最优的催化效率，EC转化率达到63.55％，DMC选择性达到95.34％。
实施例10
以单一的正硅酸乙酯水解后的二氧化硅为载体，1,3-二甲基咪唑吡咯盐为活性组分，降低活性组分加入量时制备的催化剂对酯交换效率的影响。催化剂制备如下：将30mL正硅酸乙酯和21mL乙醇分别加入锥形瓶，加热到60℃后分别立即加入6g 1,3-二甲基咪唑吡咯盐离子液体，混合均匀后加入8.9g去离子水，体系迅速凝胶。60℃温度下老化12h，120℃干燥10h后用50mL乙醇洗涤三次，150℃真空干燥3h即得固载后催化剂。
表5包埋不同1,3-二甲基咪唑吡咯盐质量对EC和MeOH反应的影响
Figure PCTCN2019124323-appb-000009
EC/MeOH＝1/6，包埋量1,3-二甲基咪唑吡咯盐，反应温度76-77℃，催化剂装填4g，质量空速1h -1，反应1800min
以正硅酸乙酯水解后的二氧化硅为载体，即使包埋6g的1,3-二甲基咪唑吡咯盐离子液体也展现出51.55％的EC转化率以及91.87％的DMC选择性。
实施例11
以钛酸四丁酯水解后的二氧化钛为载体，60℃水解分别嵌铆式包埋12g 1-乙基-3-甲基咪唑吡咯盐、1-乙基-3-甲基咪唑吗啉盐、1-丁基-3-甲基咪唑咪唑盐、1,3-二甲基咪唑吡咯盐、N-甲基-N-乙基吗啉吗啉盐以及N-甲基-N-丁基吗啉吡咯盐。采用固定床反应器对制备的非均相催化剂进行评价，反应条件为：反应原料碳酸乙烯酯与甲醇摩尔 比为1:6，反应温度76-77℃，催化剂装填质量为4g，反应原料的质量空速为1h -1，即原料每小时进样量为4g，每个催化剂连续评价时间为不超过1800min。不同嵌入包埋的离子液体催化剂活性如表6所示。
表6嵌入包埋不同离子液体催化剂对EC和MeOH反应的影响
Figure PCTCN2019124323-appb-000010
EC/MeOH＝1/6，包埋量12g，反应温度76-77℃，催化剂装填4g，质量空速1h -1，反应1800min
以钛酸四丁酯水解后的二氧化钛为载体嵌铆各种离子液体均表现出明显低于二氧化硅的催化活性，EC转化率在40％-45％之间，DMC选择性除1,3-二甲基咪唑吡咯盐以外均低于40％。
实施例12
以正硅酸乙酯和钛酸四丁酯混合水解后氧化物为载体，包埋1-乙基-3-甲基咪唑吡咯盐离子液体。14.5mL正硅酸乙酯和25mL乙醇分别加入锥形瓶，加入23mL钛酸四丁酯，然后加入结构助剂5.08g乙酸锌，4.96g乙酸镁以及1.89g偏铝酸钠混合均匀后加入9.35g去离子水。60℃温度下老化12h，120℃干燥10h后用50mL乙醇洗涤三次，150℃真空干燥3h即得固载后的离子液体催化剂。采用固定床反应器对制备的非均相催化剂进行评价，反应条件为：反应原料碳酸乙烯酯与甲醇摩尔比为1:6，反应温度76-77℃，催化剂装填质量为4g，反应原料的质量空速为1h -1，即原料每小时进样量为4g，每个催化剂连续评价时间为不超过1800min。EC转化率为56.78％，DMC选择性为62.39％，明显比单纯钛酸四丁酯包埋的各种离子液体催化剂催化碳酸乙烯酯交换效率高，其DMC收率为钛酸四丁酯包埋法收率的2.25倍。
实施例13
以二氧化硅为载体，浸渍6g的1-乙基-3-甲基-咪唑咪唑盐催化剂以及嵌入包埋量分别为3、6和12g的催化剂红外光谱如图9所示。位于1064cm -1处的强吸收峰为Si-O-Si的伸缩振动特征峰，3427cm -1吸收峰为醇O-H基伸缩振动，1631cm -1为咪唑环上的C＝C特征吸收峰，咪唑环的特征吸收峰的位置位于797cm -1处。说明开发的嵌入包埋法制备的离子液体固载催化剂的方法是可信和可行的，离子液体活性组分确定包埋入非均相催化剂中。所制备的催化剂中咪唑特征峰的高度严格遵照包埋法3、6以及12的规律增加，6g离子液体浸渍法制备的催化剂也展示出与高于3g包埋法但明显低于6g包埋法的咪唑特征峰强度，这与他们的催化活性关系基本一致。
实施例14
以二氧化硅为载体，浸渍6g1-乙基-3-甲基-咪唑咪唑盐以及嵌入包埋量分别为3、6和12g的催化剂SEM谱如图10所示。
图10可以看出，图a表观形貌为条状结构，图b呈现出规则的二氧化硅分子的形态，其原因是加入的离子液体量少而不足以形成杂乱的硅烷载体与离子液体的复合体结构。图c、d包埋后的离子液体表观形貌发生较大的改变，载体上聚集了杂乱无章的小颗粒，形成了无规的硅烷载体与离子液体的复合体，进一步说明离子液体通过硅烷偶联作用成功负载到载体上，且随负载量的增大，团簇现象越明显，该SEM图充分说明了嵌入包埋法导致合成的离子液体通过硅烷基偶联作用分布在二氧化物三维网络中，其微观结构明显区别与二氧化硅的表面微观结构。
以上所述，仅是本申请的几个实施例，并非对本申请做任何形式的限制，虽然本申请以较佳实施例揭示如上， 然而并非用以限制本申请，任何熟悉本专业的技术人员，在不脱离本申请技术方案的范围内，利用上述揭示的技术内容做出些许的变动或修饰均等同于等效实施案例，均属于技术方案范围内。

Claims (38)

  1. 一种碳酸二甲酯的制备方法，其特征在于，包括以下步骤：
    将含有碳酸乙烯酯和甲醇的原料，与催化剂接触，反应，得到所述碳酸二甲酯；
    所述催化剂包括离子液体；
    所述离子液体包括阴离子和阳离子；
    所述阴离子和阳离子均含有含氮杂环。
  2. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，所述反应的温度为60～80℃；
    优选地，所述反应的温度为66～69℃。
  3. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，所述反应的温度为76～77℃。
  4. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，
    所述阳离子具有式I或式II所示的结构；
    Figure PCTCN2019124323-appb-100001
    所述阴离子具有式III、式IV或式V所示的结构；
    Figure PCTCN2019124323-appb-100002
    其中，R 1、R 2独立地选自C1-C6的烷烃基、C2-C6的烯烃基、C3-C6的芳烃基中的一种。
  5. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，所述含有碳酸乙烯酯和甲醇的原料中碳酸乙烯酯和甲醇的摩尔比为1:1～1:15。
  6. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，所述含有碳酸乙烯酯和甲醇的原料中碳酸乙烯酯和甲醇的摩尔比为1:4～1:15。
  7. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，所述含有碳酸乙烯酯和甲醇的原料中碳酸乙烯酯和甲醇的摩尔比为1:10～1:15。
  8. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，所述反应的时间为1分钟～30小时。
  9. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，68℃下，反应5min以内达到化学平衡。
  10. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，68℃下，反应1min达到化学平衡。
  11. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，R 1、R 2独立地选自-CH 3、-CH 2CH 3、-(CH 2) 2CH 3、-(CH 2) 3CH 3中的一种。
  12. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，所述催化剂还包括载体；
    所述离子液体嵌铆式包埋在所述载体中。
  13. 根据权利要求12所述的碳酸二甲酯的制备方法，其特征在于，所述离子液体嵌入所述载体的网络中。
  14. 根据权利要求12所述的碳酸二甲酯的制备方法，其特征在于，所述载体与所述离子液体存在以下作用力中的至少一种：偶联作用、氢键作用。
  15. 根据权利要求12所述的碳酸二甲酯的制备方法，其特征在于，所述催化剂中离子液体与载体重量比例为0.01～0.3：0.1～0.6。
  16. 根据权利要求12所述的碳酸二甲酯的制备方法，其特征在于，所述载体选自二氧化硅、二氧化钛、三氧化二铝中的至少一种；
    所述载体形成的同时，所述离子液体嵌入所述载体的网络中。
  17. 根据权利要求12所述的碳酸二甲酯的制备方法，其特征在于，所述催化剂中还包括结构助剂；
    所述离子液体嵌入所述载体与所述结构助剂复合的网络中。
  18. 根据权利要求12所述的碳酸二甲酯的制备方法，其特征在于，所述结构助剂包括Mg、Ca、Ba、La、Ce、Zr、Fe、Zn、Li、Cs、Al中的至少一种。
  19. 根据权利要求12所述的碳酸二甲酯的制备方法，其特征在于，所述结构助剂在所述催化剂中的重量含量为10％～60％。
  20. 根据权利要求1所述的碳酸二甲酯的制备方法，其特征在于，所述离子液体的制备方法包括以下步骤：
    a1)向含有离子液体阴离子源的溶液I中，加入碱，反应，得到离子液体阴离子金属盐；
    a2)将所述离子液体阴离子金属盐溶解在溶剂中，加入离子液体阳离子盐，反应，得到所述离子液体。
  21. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，步骤a1)中，所述溶液I中的溶剂选自乙醇、苯、甲苯、二甲苯中的至少一种；
    所述碱为有机碱或无机碱；
    所述有机碱包括甲醇钠、乙醇钠、叔丁醇钠、甲醇钾、乙醇钾或叔丁醇钾；
    所述无机碱包括氢氧化钠或氢氧化钾；
    所述离子液体阴离子金属盐选自离子液体阴离子Na盐、离子液体阴离子K盐中的至少一种。
  22. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，步骤a1)中，所述溶液I中，离子液体阴离子源的浓度为0.05～0.8g/mL；
    所述离子液体阴离子源与所述碱的摩尔比为0.9～1.1。
  23. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，步骤a1)中，所述离子液体阴离子源包括咪唑、吡咯或者吗啉。
  24. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，步骤a1)中，所述反应的条件为：50～80℃下反应5～12小时。
  25. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，步骤a1)还包括：反应结束后，除去溶剂，得到咪唑阴离子盐、吡咯阴离子盐或者吗啉阴离子盐。
  26. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，步骤a2)中，所述溶剂包括带水剂；
    所述带水剂选自乙醇、苯、甲苯、二甲苯中的至少一种；
    所述离子液体阳离子盐选自1-R 1-3-甲基-咪唑溴盐、1-R 1-3-甲基-咪唑碘盐、N-甲基-N-R 2-吗啉溴盐、N-甲基-N-R 2-吗啉碘盐中的至少一种。
  27. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，步骤a2)中，所述离子液体阴离子金属盐与溶剂的比例为0.1～0.9：0.05～1.2g/mL。
  28. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，步骤a2)中，所述反应的条件为：25～80℃下反应12～48h。
  29. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，步骤a2)还包括：反应结束后，除去溶剂，得到所述离子液体。
  30. 根据权利要求20所述的碳酸二甲酯的制备方法，其特征在于，所述催化剂的制备方法还包括步骤b)：
    将水加入到含有载体前驱体和离子液体的混合物中，水解，得到所述催化剂。
  31. 根据权利要求30所述的碳酸二甲酯的制备方法，其特征在于，步骤b)中，所述载体前驱体包括正硅酸乙酯、钛酸四丁酯、异丙醇铝、偏铝酸钠中的至少一种。
  32. 根据权利要求30所述的碳酸二甲酯的制备方法，其特征在于，步骤b)中所述混合物中还包括溶剂；
    所述溶剂在所述混合物中的重量含量为10％～90％；
    所述溶剂包括甲醇、乙醇、丙醇、丁醇、乙酸甲酯、乙酸乙酯中的至少一种。
  33. 根据权利要求30所述的碳酸二甲酯的制备方法，其特征在于，步骤b)中，
    所述载体前驱体、离子液体、水的摩尔比为0.2～0.8：0.03～0.4：0.1～0.4。
  34. 根据权利要求30所述的碳酸二甲酯的制备方法，其特征在于，步骤b)中，所述水解的温度为25～80℃。
  35. 根据权利要求30所述的碳酸二甲酯的制备方法，其特征在于，步骤b)中，水解后，40～120℃之间老化6～24小时，得到所述催化剂。
  36. 根据权利要求30所述的碳酸二甲酯的制备方法，其特征在于，步骤b)，所述混合物中包括结构助剂前驱体；
    所述结构调助剂前驱体包括结构助剂相应的醋酸盐、硅酸盐、盐酸盐、硝酸盐中的至少一种。
  37. 根据权利要求30所述的碳酸二甲酯的制备方法，其特征在于，步骤b)还包括：
    将载体前驱体、结构助剂前驱体与溶剂混合，加入离子液体，混合均匀，然后加入水，进行水解，得到所述催化剂。
  38. 根据权利要求30所述的碳酸二甲酯的制备方法，其特征在于，步骤b)，所述载体前驱体、结构助剂前驱体、溶剂、离子液体、水的质量比为0.2～0.8:0.05～0.4：0.3～0.8：0.03～0.4：0.1～0.4。
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