Catalyst for synthetic reaction of propylene carbonate as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for synthetic reaction of propylene carbonate as well as a preparation method and application of the catalyst. The catalyst comprises a component I and a component II; the component I is a reaction product of alkyl glycol, halide salt and glycerol triglycidyl ether; and the component II is a bis-imidazolium salt solution obtained by reacting alkyl imidazole and dihalogenated alkane in a solvent propylene carbonate. The catalyst is suitable for the reaction of synthesizing propylene carbonate from CO2 and epoxypropane. The catalyst is applied to the reaction, the reaction condition is mild, the catalytic activity and the stability are good, and particularly the catalytic activity and the stability of the catalyst under the low-temperature reaction condition are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the field of propylene carbonate synthesis, and particularly relates to a catalyst for propylene carbonate synthesis reaction, a preparation method and an application thereof. Background Art

[0002] Propylene carbonate is an excellent organic solvent and organic intermediate. Currently, propylene carbonate is produced by the catalytic cycloaddition of propylene oxide with carbon dioxide. This reaction achieves nearly 100% carbon dioxide conversion and is an important approach for reducing CO2 emissions. The industrial reaction process utilizes a homogeneous catalyst and a tubular reactor, followed by product separation via distillation. KI and tetraethylammonium bromide (TEABr) are the most commonly used homogeneous catalysts. They exhibit high conversion rates and selectivity under high pressure. Other metal salts, quaternary ammonium salts, and quaternary phosphonium salts are also excellent catalysts. Increasing the ionization of the catalyst metal salt during the reaction can enhance catalytic activity. Therefore, chelating the metal salt with polyethylene glycol or crown ether can further enhance catalytic activity at reduced reaction pressure and temperature.

[0003] Ionic liquids are an important class of catalysts, primarily imidazolium-based ionic liquids. They possess extremely high catalytic activity, and their catalytic performance can be further enhanced by grafting various functional groups onto them, such as alcoholic hydroxyl groups or carboxyl groups.

[0004] CN106967041A discloses a homogeneous catalyst composition of an amino acid-type eutectic agent and zinc bromide. The catalyst composition has high activity. Using a kettle reactor, the reaction is carried out at 1.2 MPa and 150°C for 5 hours. The conversion rate of propylene oxide reaches 99%, and the selectivity of propylene carbonate reaches 98%.

[0005] CN112939924A discloses a metal complex catalyst, the chemical composition of which is (ZnX) · [Fe(CN) 4 · mL] · (ZnX2) n The activity of the catalyst is very high. Using a kettle reactor, the reaction is carried out at 0.6MPa and 120℃ for 2h, the conversion rate of propylene oxide reaches 88%, and the selectivity of propylene carbonate reaches 99.5%.

[0006] The main problem with currently used homogeneous catalysts is their low catalytic activity and strict reaction conditions. For example, the reaction temperature must be above 120°C to achieve a conversion rate of over 88%. Summary of the Invention

[0007] To address the problems of the prior art, the present invention provides a catalyst for propylene carbonate synthesis, its preparation method, and its application. The catalyst is suitable for the synthesis of propylene carbonate from CO2 and propylene oxide. Application of the catalyst in this reaction allows for mild reaction conditions, good catalytic activity and stability, and particularly significantly improves the catalyst's catalytic activity and stability under low-temperature reaction conditions.

[0008] In a first aspect, the present invention provides a catalyst for propylene carbonate synthesis. The catalyst comprises component I and component II; component I is the reaction product of an alkyl glycol, a halide salt, and glycerol triglycidyl ether; and component II is a bisimidazolium salt solution obtained by reacting an alkyl imidazole and a dihalogenated alkane in propylene carbonate as a solvent.

[0009] According to the present invention, in the catalyst, the weight ratio of component I to component II is 1:(0.8-2).

[0010] According to the present invention, the alkyl glycol comprises at least one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol, preferably ethylene glycol. The halide salt comprises at least one of aluminum halide, iron halide, and zinc halide, preferably zinc bromide. The molar ratio of the alkyl glycol, halide salt, and glycerol triglycidyl ether is 1:1-2:1-2, preferably 1:1-2:1.1-1.5. The catalyst component I is obtained by reacting the alkyl glycol, halide salt, and glycerol triglycidyl ether.

[0011] According to the present invention, the alkylimidazole is 1-alkylimidazole, preferably including at least one of 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole, and 1-butylimidazole, with 1-methylimidazole being preferred. The dihaloalkane includes at least one of 1,2-dihaloethane, 1,3-dihalopropane, 1,4-dihalobutane, 1,5-dihalopentane, and 1,6-dihalohexane, with 1,2-dibromoethane being preferred. The molar ratio of the alkylimidazole to the dihaloalkane to propylene carbonate is 1:(0.8-1.2):(4-8). The catalyst component II is obtained by reacting the alkylimidazole and the dihaloalkane in propylene carbonate as a solvent.

[0012] A second aspect of the present invention provides a method for preparing a catalyst for propylene carbonate synthesis. The method comprises:

[0013] (1) mixing an alkyl glycol, a halide salt, and glycerol triglycidyl ether to react to obtain component I;

[0014] (2) mixing alkyl imidazole, dihalogenated alkane, and propylene carbonate, heating and refluxing to obtain component II;

[0015] (3) Component I and component II are mixed uniformly to obtain the catalyst.

[0016] According to the present invention, in step (1), the alkyl glycol comprises at least one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol, preferably ethylene glycol. The halide salt is at least one of aluminum halide, iron halide, and zinc halide, preferably zinc bromide. The molar ratio of the alkyl glycol, halide salt, and glycerol triglycidyl ether is 1:1-2:1-2, preferably 1:1-2:1.1-1.5.

[0017] According to the present invention, the reaction apparatus in step (1) can be an autoclave. The reaction conditions are: reaction at 90-120°C for 1-12 hours. The reaction is carried out under stirring. The reaction product is yellow.

[0018] According to the present invention, in step (1), the timing of adding the halide salt is not particularly limited; the halide salt can be added simultaneously with the alkyl glycol and glycerol triglycidyl ether. Alternatively, the alkyl glycol and glycerol triglycidyl ether can be mixed and reacted before adding the halide salt.

[0019] According to the present invention, the alkylimidazole in step (2) is 1-alkylimidazole, including at least one of 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole, and 1-butylimidazole, preferably 1-methylimidazole; the dihaloalkane includes at least one of 1,2-dihaloethane, 1,3-dihalopropane, 1,4-dihalobutane, 1,5-dihalopentane, and 1,6-dihalohexane, preferably 1,2-dibromoethane. The molar ratio of the alkylimidazole, dihaloalkane, and propylene carbonate is 1:(0.8-1.2):(4-8).

[0020] According to the present invention, the temperature of the heating reflux reaction in step (2) is 90-110° C. and the time is 4-10 hours. The product prepared is a bisimidazolium salt with a light yellow color.

[0021] According to the present invention, in step (3), the weight ratio of component I to component II is 1:(0.8-2). The reaction apparatus can be a glass kettle.

[0022] The third aspect of the present invention provides the use of the above catalyst in the synthesis of propylene carbonate.

[0023] According to the present invention, the application is that CO2 contacts and reacts with propylene oxide in the presence of a catalyst.

[0024] According to the present invention, the reaction conditions are: a volume ratio of the catalyst to propylene oxide of 1:(1000-5000), a molar ratio of CO2 to propylene oxide of 1.1:1-1.5:1, a reaction residence time of 30-100 minutes, a reaction pressure of 0.6-2 MPa, and a reaction temperature of 50-100°C, preferably 50-85°C.

[0025] Compared with existing catalysts, the catalyst of the present invention has the following characteristics:

[0026] (1) Component I in the catalyst of the present invention is the reaction product of an alkyl glycol, a halide salt, and glycerol triglycidyl ether. It has strong metal complexing properties, promoting the dissolution of the metal salt in the reactants and the release of halide ions, thereby enhancing the activity of the catalyst. Component I and component II exhibit a synergistic catalytic effect, significantly enhancing the catalytic activity of the catalyst under low-temperature reaction conditions. Using this catalyst, efficient synthesis of propylene carbonate can be achieved at near-room temperature.

[0027] (2) The catalyst of the present invention has remarkable stability and the catalytic activity does not decrease after multiple cycles of reaction.

[0028] (3) The preparation process of the catalyst of the present invention does not generate any waste and is environmentally friendly. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below with reference to specific embodiments.

[0030] Example 1

[0031] (1) 62 g of ethylene glycol, 270 g of zinc bromide and 312 g of glycerol triglycidyl ether were added to an autoclave, heated to 100° C., and stirred for reaction for 6 hours to obtain component I.

[0032] (2) 82 g of methylimidazole, 205 g of 1,2-dibromoethane, and 408 g of propylene carbonate were mixed and heated under reflux at 100° C. for 6 hours to obtain component II.

[0033] (3) According to the weight ratio of component I to component II being 1:1.1, component I of step (1) and component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst C1.

[0034] Example 2

[0035] (1) 62 g of ethylene glycol, 360 g of zinc bromide and 416 g of glycerol triglycidyl ether were added to an autoclave, heated to 110° C., and stirred for reaction for 8 hours to obtain component I.

[0036] (2) 82 g of methylimidazole, 187 g of 1,2-dibromoethane, and 816 g of propylene carbonate were mixed and heated under reflux at 100° C. for 4 hours to obtain component II.

[0037] (3) According to the weight ratio of component I to component II of 1:1.3, the component I of step (1) and the component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst C2.

[0038] Example 3

[0039] (1) 62 g of ethylene glycol, 270 g of zinc bromide and 468 g of glycerol triglycidyl ether were added to an autoclave, heated to 100° C., and stirred for reaction for 12 hours to obtain component I.

[0040] (2) 82 g of methylimidazole, 224 g of 1,2-dibromoethane, and 612 g of propylene carbonate were mixed, and heated under reflux at 110° C. for 10 hours to obtain component II.

[0041] (3) According to the weight ratio of component I to component II being 1:1.2, component I of step (1) and component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst C3.

[0042] Example 4

[0043] (1) 62 g of ethylene glycol, 225 g of zinc bromide and 260 g of glycerol triglycidyl ether were added to an autoclave, heated to 120° C., and stirred for reaction for 4 hours to obtain component I.

[0044] (2) 82 g of methylimidazole, 152 g of 1,4-dichlorobutane, and 612 g of propylene carbonate were mixed and heated under reflux at 100° C. for 6 hours to obtain component II.

[0045] (3) According to the weight ratio of component I to component II of 1:1.5, the component I of step (1) and the component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst C4.

[0046] Example 5

[0047] (1) 62 g of ethylene glycol, 319 g of aluminum bromide and 312 g of glycerol triglycidyl ether were added to an autoclave, heated to 120° C., and stirred for reaction for 4 hours to obtain component I.

[0048] (2) 82 g of methylimidazole, 127 g of 1,4-dichlorobutane, and 408 g of propylene carbonate were mixed and heated under reflux at 100° C. for 6 hours to obtain component II.

[0049] (3) According to the weight ratio of component I to component II being 1:0.8, component I of step (1) and component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst C5.

[0050] Example 6

[0051] (1) 62 g of ethylene glycol, 194 g of ferric chloride and 312 g of glycerol triglycidyl ether were added to an autoclave, heated to 100° C., and stirred for reaction for 6 hours to obtain component I.

[0052] (2) 96 g of ethylimidazole, 127 g of 1,4-dichlorobutane, and 408 g of propylene carbonate were mixed and heated under reflux at 100° C. for 6 hours to obtain component II.

[0053] (3) According to the weight ratio of component I to component II being 1:1.1, component I of step (1) and component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst C6.

[0054] Example 7

[0055] (1) 76 g of 1,3-propylene glycol, 270 g of zinc bromide and 312 g of glycerol triglycidyl ether were added to an autoclave, heated to 100° C., and stirred for reaction for 6 hours to obtain component I.

[0056] (2) 96 g of ethylimidazole, 127 g of 1,4-dichlorobutane, and 408 g of propylene carbonate were mixed and heated under reflux at 100° C. for 6 hours to obtain component II.

[0057] (3) According to the weight ratio of component I to component II being 1:0.9, component I of step (1) and component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst C7.

[0058] Example 8

[0059] (1) 90 g of 1,4-butanediol, 270 g of zinc bromide and 312 g of glycerol triglycidyl ether were added to an autoclave, heated to 100° C., and stirred for reaction for 6 hours to obtain component I.

[0060] (2) 96 g of ethylimidazole, 152 g of 1,4-dichlorobutane, and 816 g of propylene carbonate were mixed, and heated under reflux at 90° C. for 10 hours to obtain component II.

[0061] (3) According to the weight ratio of component I to component II being 1:2, component I of step (1) and component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst C8.

[0062] Comparative Example 1

[0063] The difference from Example 1 is that no ethylene glycol is added to the catalyst raw material.

[0064] (1) 270 g of zinc bromide and 312 g of glycerol triglycidyl ether were added to an autoclave, heated to 100° C., and stirred for reaction for 6 hours to obtain component I.

[0065] (2) 82 g of methylimidazole, 205 g of 1,2-dibromoethane, and 408 g of propylene carbonate were mixed and heated under reflux at 100° C. for 6 hours to obtain component II.

[0066] (3) According to the weight ratio of component I to component II being 1:1.1, component I of step (1) and component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst DC1.

[0067] Comparative Example 2

[0068] The difference from Example 1 is that glycerol triglycidyl ether is not added to the catalyst raw material.

[0069] (1) Add 62 g of ethylene glycol and 270 g of zinc bromide into an autoclave, heat to 100° C., and stir to react for 6 hours to obtain component I.

[0070] (2) 82 g of methylimidazole, 205 g of 1,2-dibromoethane, and 408 g of propylene carbonate were mixed and heated under reflux at 100° C. for 6 hours to obtain component II.

[0071] (3) According to the weight ratio of component I to component II being 1:1.1, component I of step (1) and component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst DC2.

[0072] Comparative Example 3

[0073] (1) 264 g of 18-crown ether-6 and 270 g of zinc bromide were added to an autoclave, heated to 60° C., and stirred for reaction for 2 hours to obtain component I.

[0074] (2) 82 g of methylimidazole, 205 g of 1,2-dibromoethane, and 408 g of propylene carbonate were mixed and heated under reflux at 100° C. for 6 hours to obtain component II.

[0075] (3) According to the weight ratio of component I to component II being 1:1.1, component I of step (1) and component II of step (2) were mixed uniformly in a glass kettle to obtain the catalyst DC3.

[0076] Comparative Example 4

[0077] The difference from Example 1 is that there are no steps 1 and 3 in the catalyst preparation process, namely:

[0078] 82 g of methylimidazole, 205 g of 1,2-dibromoethane, and 408 g of propylene carbonate were mixed, and heated under reflux at 100° C. for 6 hours to obtain catalyst DC4.

[0079] Application Examples

[0080] The catalytic performance of the catalysts of Examples 1-8 and Comparative Examples 1-4 in the propylene carbonate synthesis reaction was tested. The reaction conditions were as follows: a catalyst to propylene oxide volume ratio of 1:3000, a CO2 to propylene oxide molar ratio of 1.2:1, a reaction residence time of 60 minutes, a reaction pressure of 1 MPa, and a reaction temperature of 60°C. The apparatus used was a tubular microreactor. The reactor had a diameter of 50 mm and a length of 1200 mm. After checking for airtightness, the catalyst and reactants were injected into the reaction tube and the temperature was raised to the reaction temperature. After the reaction temperature was maintained constant for 1 hour, sampling began. The evaluation results are shown in Table 2. The reaction results demonstrate that the catalyst of the present invention is highly active. Under the reaction conditions, the conversion rate of the reactant propylene oxide is very high, and the product selectivity can reach over 99%. Furthermore, when Component I of Example 1 was used as the catalyst and tested under the same reaction conditions, the conversion rate of propylene oxide was only 55 mol%, far lower than the performance of the catalyst of the present invention. This indicates that the bisimidazolium salt and the polyether mixture have a synergistic catalytic effect, and the catalyst has significant catalytic activity under low-temperature reaction conditions.

[0081] Table 2 Catalyst evaluation results

[0082]

[0083]

[0084] The reaction products of Examples 1-8 and Comparative Example 3 were distilled to separate the catalysts, which were then reintroduced into the reaction for a cyclic reaction under the same reaction conditions. After five cycles, the activity of the catalysts in the Examples remained essentially unchanged, while the activity of the catalyst in Comparative Example 3 was significantly reduced. The results of the five cycles are shown in Table 3.

[0085] Table 3 Catalyst cycle evaluation results

[0086]

Claims

1. A catalyst for propylene carbonate synthesis, comprising component I and component II; component I is the reaction product of an alkyl glycol, a halide salt, and glycerol triglycidyl ether; and component II is a bisimidazolium salt solution obtained by reacting an alkyl imidazole and a dihalogenated alkane in propylene carbonate as a solvent.

2. The catalyst according to claim 1, characterized in that The weight ratio of component I to component II is 1:(0.8-2).

3. The catalyst according to claim 1, characterized in that The alkyl glycol includes at least one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 1,4-butylene glycol; And / or, the halide salt is at least one of aluminum halide, iron halide, and zinc halide; And / or, the molar ratio of the alkyl glycol, the halide salt and glycerol triglycidyl ether is 1:1-2:1-2, preferably 1:1-2:1.1-1.

5.

4. The catalyst according to claim 1, characterized in that The alkylimidazole is a 1-alkylimidazole, preferably including at least one of 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole, and 1-butylimidazole, preferably 1-methylimidazole; And / or, the dihaloalkane includes at least one of 1,2-dihaloethane, 1,3-dihalopropane, 1,4-dihalobutane, 1,5-dihalopentane, and 1,6-dihalohexane, preferably 1,2-dibromopentane; And / or, the molar ratio of the alkylimidazole, dihalogenated alkane and propylene carbonate is 1:(0.8-1.2):(4-8).

5. A method for preparing a catalyst for propylene carbonate synthesis reaction, comprising: (1) mixing an alkyl glycol, a halide salt, and glycerol triglycidyl ether to react to obtain component I; (2) mixing alkyl imidazole, dihalogenated alkane, and propylene carbonate, heating and refluxing to obtain component II; (3) Component I and component II are mixed uniformly to obtain the catalyst.

6. The preparation method according to claim 5, characterized in that: The alkyl glycol includes at least one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 1,4-butylene glycol; And / or, the halide salt is at least one of aluminum halide, iron halide, and zinc halide; And / or, the molar ratio of the alkyl glycol, the halide salt and glycerol triglycidyl ether is 1:1-2:1-2, preferably 1:1-2:1.1-1.

5.

7. The preparation method according to claim 5, characterized in that: The alkylimidazole is a 1-alkylimidazole, preferably including at least one of 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole, and 1-butylimidazole, preferably 1-methylimidazole; And / or, the dihaloalkane includes at least one of 1,2-dihaloethane, 1,3-dihalopropane, 1,4-dihalobutane, 1,5-dihalopentane, and 1,6-dihalohexane, preferably 1,2-dibromoethane; And / or, the molar ratio of the alkylimidazole, dihalogenated alkane and propylene carbonate is 1:(0.8-1.2):(4-8).

8. The preparation method according to claim 5, characterized in that: The weight ratio of component I to component II is 1:(0.8-2).

9. The method according to claim 5, characterized in that: The reaction conditions of step (1) are: reaction at 90-120° C. for 1-12 hours; and / or, the temperature of the heating reflux reaction in step (2) is 90-110° C. for 4-10 hours.

10. Use of the catalyst according to any one of claims 1 to 4 or the catalyst prepared by the method according to any one of claims 5 to 9 in the synthesis of propylene carbonate.

11. The application according to claim 10, characterized in that: The application is that CO2 contacts propylene oxide in the presence of a catalyst to react.

12. The use according to claim 10, characterized in that: The reaction conditions are as follows: a volume ratio of the catalyst to propylene oxide of 1:(1000-5000), a molar ratio of CO2 to propylene oxide of 1.1:1-1.5:1, a reaction residence time of 30-100 minutes, a reaction pressure of 0.6-2 MPa, and a reaction temperature of 50-100°C, preferably 50-85°C.

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