阅读说明：本技术 一种离子液体催化剂及其制备方法和用途 (Ionic liquid catalyst and preparation method and application thereof ) 是由 吴雷雷 张辉 李宝晨 赵彦鹏 彭永文 于 2020-06-28 设计创作，主要内容包括：本发明公开一种离子液体催化剂及其制备方法和应用。其中离子液体催化剂,原料为N-烷基咪唑、卤代烷基醇和卤代锌盐,其中N-烷基咪唑、卤代烷基醇和卤代锌盐的摩尔比为1:1～1.5:1.5～2.0。方法包括：将N-烷基咪唑注入至反应器中,加热至80～100℃；将卤代烷基醇搅拌条件下缓慢注入至反应器内,并控制温度在50～70℃,并在该温度条件下恒温保持4～5个小时,用真空泵抽真空,将未反应卤代烷基醇蒸出；将卤代锌盐加入至反应器中,在70～80℃条件下恒温混合2～3小时后取出,得到离子液体催化剂,其中,上述步骤中所述的N-烷基咪唑、卤代烷基醇和卤代锌盐的摩尔比为1:1～1.5:1.5～2.0。该离子液催化剂,更有助于溶解CO2和环氧化合物,从而促进羰基化反应进行。(The invention discloses an ionic liquid catalyst and a preparation method and application thereof. The ionic liquid catalyst is prepared from N-alkyl imidazole, halogenated alkyl alcohol and halogenated zinc salt, wherein the molar ratio of the N-alkyl imidazole to the halogenated alkyl alcohol to the halogenated zinc salt is 1: 1-1.5: 1.5-2.0. The method comprises the following steps: injecting N-alkyl imidazole into a reactor, and heating to 80-100 ℃; slowly injecting halogenated alkyl alcohol into the reactor under the stirring condition, controlling the temperature to be 50-70 ℃, keeping the temperature for 4-5 hours at the constant temperature, vacuumizing by using a vacuum pump, and steaming out unreacted halogenated alkyl alcohol; adding halogenated zinc salt into a reactor, mixing for 2-3 hours at a constant temperature of 70-80 ℃, and taking out to obtain the ionic liquid catalyst, wherein the molar ratio of the N-alkyl imidazole, the halogenated alkyl alcohol and the halogenated zinc salt in the step is 1: 1-1.5: 1.5-2.0. The ionic liquid catalyst is more helpful for dissolving CO2 and epoxy compounds, thereby promoting the carbonylation reaction.)

1. The ionic liquid catalyst is prepared from N-alkyl imidazole, halogenated alkyl alcohol and halogenated zinc salt as raw materials, wherein the molar ratio of the N-alkyl imidazole to the halogenated alkyl alcohol to the halogenated zinc salt is 1: 1-1.5: 1.5-2.0.

2. An ionic liquid catalyst according to claim 1, wherein the N-alkyl imidazole is selected from N-methyl imidazole, N-ethyl imidazole or N-propyl imidazole.

3. An ionic liquid catalyst according to claim 1, wherein the alkyl halide is selected from 4-chlorobutanol, 4-bromobutanol or 4-iodobutanol.

4. An ionic liquid catalyst according to claim 1, wherein the zinc halide salt is selected from ZnCl₂、ZnBr₂Or ZnI₂。

5. A method of producing the ionic liquid catalyst of any one of claims 1 to 4, comprising the steps of:

injecting N-alkyl imidazole into a reactor, and heating to 80-100 ℃;

slowly injecting halogenated alkyl alcohol into the reactor under the stirring condition, controlling the temperature to be 50-70 ℃, keeping the temperature for 4-5 hours at the constant temperature, vacuumizing by using a vacuum pump, and evaporating the unreacted halogenated alkyl alcohol;

adding halogenated zinc salt into the reactor, mixing for 2-3 hours at a constant temperature of 70-80 ℃, and taking out to obtain the ionic liquid catalyst, wherein the molar ratio of the N-alkyl imidazole, the halogenated alkyl alcohol and the halogenated zinc salt in the step is 1: 1-1.5: 1.5-2.0.

6. The application of the ionic liquid catalyst in the preparation of ethylene carbonate according to any one of claims 1 to 4, wherein ethylene oxide and the ionic liquid catalyst are placed in a reaction kettle, carbon dioxide is introduced according to the molar ratio of ethylene oxide to carbon dioxide of 1: 1-2, the reaction temperature is 100-150 ℃, the reaction pressure is 0.5-6 MPa, the reaction time is 2-3 hours, and ethylene carbonate can be obtained through reduced pressure distillation.

Technical Field

The invention relates to the technical field of catalyst synthesis, in particular to an ionic liquid catalyst used as a catalyst when ethylene oxide and carbon dioxide are used for preparing ethylene carbonate; the invention also relates to a preparation method and application of the ionic liquid catalyst.

Background

The synthesis of ethylene carbonate from ethylene oxide and carbon dioxide is widely studied, and the research and development of high-efficiency catalysts are the key work of the research. The catalyst commonly used at present comprises a Lewis acid metal compound and a Lewis base, wherein the Lewis acid metal compound used comprises an alkali (earth) metal halide, a transition metal salt, a transition metal or a main group metal complex, and the Lewis base used comprises an organic base, a quaternary ammonium salt, a quaternary phosphonium salt, a crown ether and the like. More heterogeneous catalytic systems are used including metal oxide systems and the like.

These catalytic systems have the disadvantages of low activity and selectivity, partially use of highly toxic organic solvents, and difficult catalyst separation in homogeneous catalytic systems. The heterogeneous catalyst system has the disadvantages of low activity, long required reaction time and the like.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a hydroxyl functional ionic liquid catalyst which has long substituent side chain, large distance between anions and cations and small electrostatic effect, and the anions show strong activation energy and nucleophilic ability, and a preparation method and application of the ionic liquid catalyst.

The ionic liquid catalyst is prepared from N-alkyl imidazole, halogenated alkyl alcohol and halogenated zinc salt as raw materials, wherein the molar ratio of the N-alkyl imidazole to the halogenated alkyl alcohol to the halogenated zinc salt is 1: 1-1.5: 1.5-2.0.

The synthesized ionic liquid catalyst has the advantages that the side chain of the imidazole substituent group is long, the distance between anions and cations is large, the electrostatic action between the anions and the imidazole substituent group is small, the anions show strong activation energy and nucleophilic ability, and the long-chain ionic liquid is more favorable for dissolving CO2 and epoxy compounds, so that the carbonyl reaction is promoted to be carried out.

As a preferred embodiment of the ionic liquid catalyst of the present invention, wherein the N-alkyl imidazole is selected from N-methyl imidazole, N-ethyl imidazole or N-propyl imidazole.

As another preferred embodiment of the ionic liquid catalyst of the present invention, wherein the halogenated alkyl alcohol is selected from the group consisting of 4-chlorobutanol, 4-bromobutanol and 4-iodobutanol.

As a further preferred embodiment of an ionic liquid catalyst according to the invention, wherein the zinc halide salt is selected from ZnCl₂、ZnBr₂Or ZnI₂。

The invention also provides a preparation method of the ionic liquid catalyst, which comprises the following steps:

injecting N-alkyl imidazole into a reactor, and heating to 80-100 ℃;

slowly injecting halogenated alkyl alcohol into the reactor under the stirring condition, controlling the temperature at 50-70 ℃, keeping the temperature for 4-5 hours at the constant temperature, vacuumizing by using a vacuum pump, and distilling out unreacted halogenated alkyl alcohol;

adding halogenated zinc salt into the reactor, mixing for 2-3 hours at a constant temperature of 70-80 ℃, and taking out to obtain the ionic liquid catalyst, wherein the molar ratio of the N-alkyl imidazole, the halogenated alkyl alcohol and the halogenated zinc salt in the step is 1: 1-1.5: 1.5-2.0.

The invention also provides an application of the ionic liquid catalyst in preparation of ethylene carbonate, wherein ethylene oxide and the ionic liquid catalyst are placed in a reaction kettle, carbon dioxide is introduced according to the molar ratio of the ethylene oxide to the carbon dioxide of 1: 1-2, the reaction temperature is 100-150 ℃, the reaction pressure is 0.5-6 MPa, the reaction time is 2-3 hours, and the ethylene carbonate can be obtained through reduced pressure distillation.

Compared with the prior art, the conversion rate of the ethylene oxide is 95-99%, the selectivity of the ethylene carbonate reaches more than 98%, the temperature and the pressure required by the reaction are reduced, the energy is saved, and the conversion efficiency is improved.

Detailed Description

The technical contents, the structural features, the achieved objects and the effects of the invention are explained in detail in the following with reference to the embodiments. The following examples are intended only to illustrate the invention in detail and are not intended to limit the scope of the invention in any way.