Catalyst for preparing dialkyl carbonate as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing dialkyl carbonate as well as a preparation method and application of the catalyst. The catalyst provided by the invention is a binuclear anion-cation ionic liquid catalyst; the A core anion is selected from at least one of tetrafluoroborate radical, hexafluorophosphate radical, perchlorate radical, bis (trifluoromethanesulfonyl) imide radical, nonafluorobutyl sulfonate radical, pentafluoroethyl sulfonate radical, trifluoromethanesulfonate radical and tris (trifluoromethanesulfonyl) methyl radical; the B core anion is selected from at least one of carbonate, phosphate radical, sulfate radical, hydrogen phthalate radical, phthalate radical, oxalate radical, acetate radical, formate radical, bromide ion, fluorine ion, chloride ion and iodide ion; the A core positive ions are azacyclo quaternary ammonium positive ions; and the B-core positive ions are alkali metal positive ions. When the catalyst is used for catalyzing the decarbonylation of the oxalic acid dialkyl ester to prepare the dialkyl carbonate, the selectivity of a target product is high, the service life of the catalyst is long, and the generation of side reactions can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the field of catalysts, and in particular relates to a catalyst for preparing dialkyl carbonate, a preparation method and an application thereof. Background Art

[0002] Dimethyl carbonate is an important organic reaction intermediate and a low-toxic and environmentally friendly chemical raw material. It has very active chemical properties and is widely used in lithium battery electrolytes, medicines, pesticides, plastics and other industrial fields.

[0003] The synthesis methods of dialkyl carbonate mainly include transesterification, urea alcoholysis, methanol oxidation carbonylation, and CO low-pressure gas phase synthesis. CN104043480A uses quaternary ammonium salt ionic liquid to catalyze the transesterification reaction of propylene carbonate and methanol to synthesize dimethyl carbonate. The catalyst has only one active center and cannot smoothly catalyze the one-step transesterification reaction to synthesize dimethyl carbonate, and the yield of dimethyl carbonate is low. CN115057777A uses urea alcoholysis, which is green and environmentally friendly, but the ammonia atoms produced are not economical to use. CN114031500A uses the oxidation carbonyl method to directly synthesize dimethyl carbonate from CO2 and methanol. The process raw materials are easy to obtain and are safer and more environmentally friendly, but the conversion rate is low and the application is limited. CN108144606A discloses a method for synthesizing dimethyl carbonate by CO low-pressure gas phase method. The process has high activity and good stability, but the method has problems such as equipment corrosion and low selectivity.

[0004] At present, the utilization rate of coal-to-ethylene glycol production capacity is only more than 50%. If the remaining capacity is fully utilized and technical transformation is carried out to produce high-value-added dimethyl carbonate, it will have high feasibility and very considerable economic benefits. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a catalyst for preparing dialkyl carbonate, a preparation method and application thereof. The catalyst of the present invention is a new type of ionic liquid catalyst with binuclear anions and cations. When the catalyst of the present invention is used to prepare dialkyl carbonate, the selectivity of the target product is high, the catalyst stability is good, and the generation of side reactions can be effectively reduced.

[0006] The first aspect of the present invention provides a catalyst for preparing dialkyl carbonate, wherein the catalyst is an ionic liquid catalyst of binuclear anions and cations, wherein the A core anion is selected from at least one of tetrafluoroborate, hexafluorophosphate, perchlorate, bistrifluoromethanesulfonyl imide, nonafluorobutylsulfonate, pentafluoroethylsulfonate, trifluoromethanesulfonate, and tris(trifluoromethanesulfonyl)methyl, preferably at least one of bistrifluoromethanesulfonyl imide, nonafluorobutylsulfonate, pentafluoroethylsulfonate, and perchlorate; the B core anion is selected from at least one of carbonate, phosphate, sulfate, hydrogen phthalate, phthalate, oxalate, acetate, formate, bromide, fluoride, chloride, and iodide, preferably at least one of carbonate, oxalate, acetate, bromide, chloride, and iodide; the A core cation is a nitrogen heterocyclic quaternary ammonium cation; and the B core cation is an alkali metal cation.

[0007] Further, the nitrogen heterocyclic quaternary ammonium cation is a product of the reaction of an nitrogen heterocyclic crown ether and a halogenated alkane. The nitrogen heterocyclic crown ether is selected from at least one of benzylaza-15-crown-5, 1-benzaza-15-crown-5-ether, 1-methoxyaza-15-crown-5, 1-methylaza-18-crown-6, 1-benzaza-18-crown-6, 1-methylaza-21-crown-7, and 1-benzaza-21-crown-7, preferably at least one of 1-methoxyaza-15-crown-5, 1-methylaza-18-crown-6, and 1-benzaza-21-crown-7.

[0008] Furthermore, the halogenated alkane is selected from at least one of chlorobutane, bromopropane, bromobutane, 2-bromobutane, fluorobutane, iodobutane, and benzyl bromide. The molar ratio of the halogenated alkane to the azacyclic crown ether is 1 to 1.7:1.

[0009] Furthermore, the alkali metal positive ion is selected from at least one of sodium ion, potassium ion and cesium ion.

[0010] The second aspect of the present invention provides a method for preparing a catalyst for preparing dialkyl carbonate, comprising:

[0011] (1) dissolving an azacyclic crown ether in an organic solvent I, adding a halogenated alkane, and reacting;

[0012] (2) dissolving the product obtained in step (1) in an organic solvent II, adding an ion exchange salt, and reacting to obtain a mononuclear anionic and cationic ionic liquid;

[0013] (3) dissolving the mononuclear anion and cation ionic liquid obtained in step (2) in alcohol, adding alkali metal salt, and refluxing to obtain the catalyst.

[0014] Further, in step (1), the azacyclic crown ether is selected from at least one of benzylaza-15-crown ether-5, 1-benza-15-crown-5-ether, 1-methoxyaza-15-crown ether-5, 1-methylaza-18-crown ether-6, 1-benza-18-crown ether-6, 1-methylaza-21-crown ether-7, and 1-benza-21-crown ether-7, preferably at least one of 1-methoxyaza-15-crown ether-5, 1-methylaza-18-crown ether-6, and 1-benza-21-crown ether-7. The concentration of the solution obtained by dissolving the azacyclic crown ether in the organic solvent I is 0.2 to 0.7 mol / L.

[0015] Furthermore, in step (1), the halogenated alkane is selected from at least one of chlorobutane, bromopropane, bromobutane, 2-bromobutane, fluorobutane, iodobutane, and benzyl bromide. The molar ratio of the halogenated alkane to the azacyclic crown ether is 1 to 1.7:1.

[0016] Furthermore, in step (1), the organic solvent I is selected from at least one of ethyl acetate, propyl acetate, toluene, xylene, and ethylbenzene, preferably ethyl acetate or toluene.

[0017] Furthermore, in step (1), the reaction temperature is 45 to 70° C., and the reaction time is 10 to 40 hours.

[0018] Furthermore, in step (1), after the reaction is completed, the lower layer of the product is taken out and washed. The washing adopts at least one of the organic solvents I, and the number of washing times is 3 to 5 times.

[0019] Furthermore, in step (2), the organic solvent II is selected from at least one of dichloromethane and chloroform. The concentration of the solution obtained by dissolving the product obtained in step (1) in the organic solvent II is 10 wt% to 30 wt%.

[0020] Furthermore, in step (2), the concentration of the ion exchange salt solution is 0.4-0.9 mol / L, and the molar ratio of the ion exchange salt to the nitrogen heterocyclic crown ether is 2-5:1.

[0021] Furthermore, in step (2), the reaction temperature is 10 to 30° C., and the reaction time is 2 to 5 hours.

[0022] Furthermore, in step (2), the cation of the ion exchange salt is selected from at least one of lithium, sodium and potassium, and the anion is selected from at least one of tetrafluoroborate, hexafluorophosphate, perchlorate, bis(trifluoromethanesulfonylimide), nonafluorobutylsulfonate, pentafluoroethylsulfonate, trifluoromethanesulfonate and tris(trifluoromethanesulfonyl)methyl, preferably at least one of bis(trifluoromethanesulfonylimide), nonafluorobutylsulfonate, pentafluoroethylsulfonate and perchlorate.

[0023] Furthermore, in step (2), after the ion exchange reaction is completed, the lower layer product is washed and distilled under reduced pressure to obtain a mononuclear anion and cation ionic liquid. The lower layer product is washed with deionized water for 3 to 5 times. The temperature of the reduced pressure distillation is 30 to 50° C., and the time of the reduced pressure distillation is 10 to 40 minutes.

[0024] Furthermore, in step (3), the alcohol is selected from at least one of methanol, ethanol, propanol, isopropanol, 1,3-propylene glycol, and butanol.

[0025] Furthermore, in step (3), the concentration of the mononuclear anion ionic liquid is 10 wt % to 30 wt %.

[0026] Further, in step (3), the cation of the alkali metal salt is selected from at least one of sodium, potassium, and cesium, and the anion is selected from at least one of carbonate, phosphate, sulfate, hydrogen phthalate, phthalate, oxalate, acetate, formate, bromide, fluoride, chloride, and iodide, preferably at least one of carbonate, oxalate, acetate, bromide, chloride, and iodide. The molar ratio of the alkali metal salt to the azacyclic crown ether is 1.2 to 3:1 in terms of cation.

[0027] Furthermore, in step (3), after the reflux is completed, the filtrate is extracted after vacuum distillation to obtain the catalyst. The reflux temperature is 60 to 80°C, and the reflux time is 1 to 4 hours. The vacuum distillation temperature is 40 to 60°C, and the vacuum distillation time is 20 to 40 minutes.

[0028] Furthermore, in step (3), the alkali metal cation is complexed with the crown ether structure, wherein the 15-crown ether-5 structure preferentially complexes with Na + Coordination, 18-crown-6 structure preferentially binds to K + Coordination, 21-crown-7 structure preferentially binds to Cs + In step (2), the cation of the ion exchange salt is different from the alkali metal cation in step (3).

[0029] The third aspect of the present invention provides an application of the catalyst, wherein the application is to use dialkyl oxalate as a reaction raw material and to carry out a decarbonylation reaction under the action of the catalyst to prepare dialkyl carbonate.

[0030] Furthermore, the dialkyl oxalate is preferably at least one of dimethyl oxalate, diethyl oxalate, and methyl ethyl oxalate.

[0031] Furthermore, the decarbonylation reaction is carried out in a distillation tower kettle. The reaction raw materials and catalyst are fed into the distillation tower kettle, mixed, and reacted, and the light components (including dialkyl carbonate and CO, etc.) generated by the reaction are extracted from the top of the tower by distillation and separated to obtain dialkyl carbonate.

[0032] Further, the reaction conditions include: reaction temperature of 150-200°C, preferably 170-195°C; reaction pressure of 0.1-0.6MPa, preferably 0.15-0.4MPa; mass ratio of reaction raw materials to catalyst of 5-20:1, preferably 8-12:1; weight space velocity of reaction raw materials of 2-10h -1 , preferably 4 to 8 hours -1 ; The tower body temperature is 90-150°C, preferably 100-130°C.

[0033] Further, the reaction mechanism is as shown in formula (1), taking dimethyl oxalate as an example, under the action of catalyst, the carbonyl group is removed to generate dimethyl carbonate. Under the action of catalyst, dimethyl carbonate can further remove carbon dioxide to generate dimethyl ether as a byproduct.

[0034]

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1. The catalyst of the present invention is a novel ionic liquid catalyst of anions and cations, wherein the A core anion has no catalytic activity, but helps to improve the stability of the ionic liquid. Compared with the ionic liquid of halide anions, the A core anion has higher thermal stability, and the formation of the ionic liquid also improves the stability of the crown ether structure; the B core anion has decarbonylation catalytic reaction activity, and thanks to the selective coordination of the metal ions of the crown ether structure, the B core anion can be phase-transferred to the reaction liquid to exert its activity. Moreover, the presence of the A core anion can adsorb the metal cation of the B core through the charge, making the crown ether-metal cation structure more stable and not easy to dissociate.

[0037] 2. In the present invention, based on the aza-crown ether compound, an ionic liquid containing a crown ether structure with high thermal stability is synthesized by a two-step method, and then a binuclear anion and cation ionic liquid is obtained by coordination with a metal salt. Specifically, it includes: (1) the aza-crown ether compound reacts with a halogenated alkane to obtain a halide ionic liquid; (2) an ionic liquid with a single anion and cation with high thermal stability is obtained by ion exchange; (3) an ionic liquid catalyst containing two anions and cations is obtained by coordination of the crown ether structure with a specific metal salt. The catalyst of the present invention is used to catalyze the decarbonylation of dialkyl oxalate to prepare dialkyl carbonate, and the selectivity of the target product is high, the service life of the catalyst is long, and the occurrence of side reactions can be effectively reduced.

[0038] 3. Compared with the traditional fixed bed reactor and kettle reactor, the reaction device of the present invention can use the CO generated by the reaction to promptly remove the target product dialkyl carbonate, prevent it from further reaction, and improve the selectivity of the target product. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The schematic diagram of the process for producing dialkyl carbonate of the present invention is as follows;

[0040] Among them, 1-reaction raw material (dialkyl oxalate); 2-catalyst; 3-product light components (including dialkyl carbonate); 4-product heavy components. DETAILED DESCRIPTION

[0041] In order to explain the present invention more clearly, the present invention is further described below in conjunction with embodiments and drawings. It should be understood by those skilled in the art that the content described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0042] In the present invention, the catalyst life is defined as the time required for the dialkyl carbonate discharge rate to decrease to 90% of the initial rate.

[0043] In the present invention, the discharge rate represents the ability of a certain amount of catalyst to produce products per hour, which is directly measured by a flow meter. The higher the discharge rate, the higher the activity of the catalyst.

[0044] Selectivity of dialkyl carbonate (%) = (discharge mass flow rate of dialkyl carbonate / molecular weight of dialkyl carbonate) / (feed mass flow rate of dialkyl oxalate / molecular weight of dialkyl oxalate) × 100%.

[0045] Combination Figure 1 The process flow of producing dialkyl carbonate of the present invention is further described by taking dimethyl oxalate as raw material: the reaction raw material dimethyl oxalate 1 and catalyst 2 are placed in a distillation tower reactor to react, and the product light component 3 obtained by the reaction is extracted from the top of the tower by distillation, and then further separated to obtain dimethyl carbonate, and the product heavy component 4 is discharged from the bottom of the distillation tower reactor.

[0046] Example 1

[0047] Dissolve 0.3mol 1-methylaza-18-crown-6 in 1L ethyl acetate, add 0.4mol chlorobutane, react at 50℃ for 20h, separate the layers, wash the lower layer with ethyl acetate three times, and then dissolve in dichloromethane to obtain a 15wt% solution. Add 0.6mol lithium bis(trifluoromethanesulfonyl)imide and 1L water, stir and react at 25℃ for 2h. Wash the lower layer with water three times, and distill at 50℃ for 10min to obtain a monocationic ionic liquid. Dissolve in ethanol to obtain a 20wt% solution, add 0.25mol potassium carbonate, reflux at 80℃ for 3h, distill the product at 50℃ for 35min, and filter the filtrate to obtain the target catalyst.

[0048] Catalyst application: Take 50g of catalyst at the bottom of the distillation tower, add 360g of dimethyl oxalate and premix at 90℃ for 1h to form a uniform and transparent dispersed solution. Introduce nitrogen to replace the bottom of the tower, and control the pressure to 0.34MPa, the reaction temperature to 180℃, stir the reaction, and continuously feed dimethyl oxalate into the bottom of the tower. The weight space velocity of dimethyl oxalate is 3h -1 The air velocity was fine-tuned according to the liquid level to keep the liquid level unchanged. The tower temperature was 130°C. Dimethyl carbonate was produced from the top of the tower. After the device was stabilized, the products were analyzed and shown in Table 1.

[0049] Embodiment 2-5

[0050] Compared with Example 1, the difference in the preparation of the catalysts in Examples 2-5 is that different types of metal salts are used (see Table 1 for details).

[0051] The catalyst evaluation method is the same as in Example 1. The results are shown in Table 1.

[0052] Table 1 Evaluation results of each case

[0053]

[0054] Embodiment 6-8

[0055] Compared with Example 1, Examples 6-8 differ in the reaction temperature when the catalyst is used.

[0056] The catalyst preparation method is the same as in Example 1. The results are shown in Table 2.

[0057] Table 2 Evaluation results of each case

[0058]

[0059] Examples 9-11

[0060] Compared with Example 1, the difference between Examples 9-11 is that different ion exchange salts are used in the preparation of the catalyst.

[0061] The catalyst evaluation method is the same as in Example 1, and the results are shown in Table 3.

[0062] Table 3 Evaluation results of each case

[0063]

[0064]

[0065] Example 12

[0066] Dissolve 0.4mol 1-methoxyaza-15-crown-5 in 1L toluene, add 0.44mol bromobutyl, react at 60℃ for 15h, separate the layers, wash the lower layer with toluene three times, and then dissolve in chloroform to obtain a 20wt% solution. Add 1.2mol potassium nonafluorobutanesulfonate and 1.5L water, stir and react at 15℃ for 3h. Wash the lower layer with water three times, and distill at 40℃ for 25min to obtain a monocationic ionic liquid. Dissolve in methanol to obtain a 15wt% solution, add 0.6mol sodium bromide, reflux at 63℃ for 2.5h, distill the product at 40℃ for 30min, and filter the filtrate to obtain the target catalyst.

[0067] Catalyst application: Take 55g of catalyst at the bottom of the distillation tower, add 360g of diethyl oxalate and premix at 90℃ for 1h to form a uniform and transparent solution. Introduce nitrogen to replace the bottom of the tower, and control the pressure to 0.15MPa, the reaction temperature to 195℃, stir the reaction, and continuously feed diethyl oxalate to the bottom of the tower. The weight space velocity of diethyl oxalate is 2.5h -1 The air velocity was fine-tuned according to the liquid level to keep the liquid level unchanged. The tower temperature was 120°C. Diethyl carbonate was produced from the top of the tower. After the device was stabilized, the products were analyzed and shown in Table 4.

[0068] Example 13

[0069] Dissolve 0.4mol 1-benzapine-21-crown ether-7 in 1L toluene, add 0.44mol 2-bromobutane, react at 60℃ for 14h, separate the layers, wash the lower layer with toluene three times, and then dissolve in chloroform to obtain a 20wt% solution. Add 1.2mol potassium nonafluorobutanesulfonate and 1.5L water, stir and react at 15℃ for 3h. Wash the lower layer with water three times, and distill at 40℃ for 25min to obtain a monocationic ionic liquid. Dissolve in methanol to obtain a 15wt% solution, add 0.3mol cesium sulfate, reflux at 63℃ for 2.5h, distill the product at 40℃ for 30min, and filter the filtrate to obtain the target catalyst.

[0070] Catalyst application: Take 55g of catalyst at the bottom of the distillation tower, add 360g of diethyl oxalate and premix at 90℃ for 1h to form a uniform and transparent solution. Introduce nitrogen to replace the bottom of the tower, and control the pressure to 0.15MPa, the reaction temperature to 195℃, stir the reaction, and continuously feed diethyl oxalate to the bottom of the tower. The weight space velocity of diethyl oxalate is 2.5h -1 The air velocity was fine-tuned according to the liquid level to keep the liquid level unchanged. The tower temperature was 120°C. Diethyl carbonate was produced from the top of the tower. After the device was stabilized, the products were analyzed and shown in Table 4.

[0071] Embodiment 14

[0072] Dissolve 0.2mol 1-methylaza-18-crown-6 and 0.2mol 1-methoxyaza-15-crown-5 in 1L toluene, add 0.44mol bromobutyl, react at 60℃ for 15h, separate the layers, wash the lower layer with toluene three times and dissolve in chloroform to obtain a 20wt% solution. Add 1.2mol lithium nonafluorobutylsulfonate and 1.5L water, stir and react at 15℃ for 3h. Wash the lower layer with water three times, distill at 40℃ for 25min to obtain a monocationic ionic liquid. Dissolve in methanol to obtain a 15wt% solution, add 0.3mol sodium bromide and 0.3mol potassium bromide, reflux at 63℃ for 2.5h, distill the product at 40℃ for 30min, and filter the filtrate to obtain the target catalyst.

[0073] Catalyst application: 55g of catalyst was taken to the bottom of the distillation tower, and 360g of diethyl oxalate was added and premixed at 90℃ for 1h to form a uniform and transparent solution. Nitrogen was introduced to replace the bottom of the tower, and the pressure was controlled to 0.15MPa, the reaction temperature was 195℃, and the reaction was stirred. The diethyl oxalate in the bottom of the tower was continuously fed, and the weight space velocity of diethyl oxalate was 2.5h-1. The space velocity was fine-tuned according to the liquid level to keep the liquid level unchanged. The tower body temperature was 120℃, and diethyl carbonate was extracted from the top of the tower. After the device was stabilized, the products were analyzed and shown in Table 4.

[0074] Table 4 Evaluation results of each case

[0075]

[0076] Comparative Example 1

[0077] Compared with Example 1, no ion exchange salt was used in the catalyst preparation process of Comparative Example 1.

[0078] Catalyst preparation: 0.3 mol of 1-methylaza-18-crown-6 was dissolved in 1 L of ethyl acetate, 0.4 mol of chlorobutane was added, and the reaction was carried out at 50°C for 20 h. The product was separated into layers, and the lower layer was washed three times with ethyl acetate and dissolved in dichloromethane to obtain a 15 wt% solution. The solution was dissolved in ethanol to obtain a 20 wt% solution, 0.25 mol of potassium carbonate was added, and the solution was refluxed at 80°C for 3 h. The product was distilled at 50°C under reduced pressure for 35 min, and the filtrate was filtered to obtain the target catalyst.

[0079] The catalyst evaluation method is the same as in Example 1. The results are shown in Table 5.

[0080] Comparative Example 2

[0081] Compared with Example 1, in the catalyst preparation process of Comparative Example 2, the nitrogen heterocyclic crown ether compound is directly coordinated with the metal salt.

[0082] Catalyst preparation: add 0.25 mol potassium carbonate to 0.3 mol 1-methylaza-18-crown-6, reflux at 80°C for 3 h, distill the product at 50°C under reduced pressure for 35 min, and filter the filtrate to obtain the target catalyst.

[0083] The catalyst evaluation method is the same as in Example 1. The results are shown in Table 5.

[0084] Comparative Example 3

[0085] Compared with Example 1, the A core anion is replaced by sulfate.

[0086] Catalyst preparation: 0.3 mol 1-methylaza-18-crown-6 was dissolved in 1 L ethyl acetate, 0.4 mol chlorobutane was added, and the reaction was carried out at 50 ° C for 20 h. The product was separated into layers, and the lower layer was washed three times with ethyl acetate and dissolved in dichloromethane to obtain a 15 wt% solution. 0.6 mol sodium sulfate and 1 L water were added, and the reaction was stirred at 25 ° C for 2 h. The lower layer was washed three times with water, and the ionic liquid of a single anion and cation was obtained by vacuum distillation at 50 ° C for 10 min. It was dissolved in ethanol to obtain a 20 wt% solution, 0.25 mol potassium carbonate was added, and the solution was refluxed at 80 ° C for 3 h. The product was vacuum distilled at 50 ° C for 35 min, and the filtrate was filtered to obtain the target catalyst.

[0087] The catalyst evaluation method is the same as in Example 1. The results are shown in Table 5.

[0088] Table 5 Evaluation results of catalysts of comparative examples 1-3

[0089] Example No. Discharge rate (g / h) Dimethyl carbonate selectivity (%) Lifespan (h) Example 1 123.6 96.4 2613 Comparative Example 1 134.3 95.1 242 Comparative Example 2 122.0 96.0 289 Comparative Example 3 114.8 87.2 58

[0090] Comparative Example 4

[0091] Compared with Example 1, the difference in Comparative Example 4 is that the catalyst and dimethyl oxalate are reacted in a closed high-pressure stirred autoclave to prepare dimethyl carbonate. 5g of catalyst and 36g of dimethyl oxalate are added to the autoclave, stirred and mixed, nitrogen is introduced for replacement, the heating jacket is heated to 180°C, stirred for reaction, and the product is analyzed after cooling after reacting for 1h, as shown in Table 6.

[0092] Table 6 Evaluation results of the catalyst of Comparative Example 4

[0093] Example No. Reactor Dimethyl carbonate selectivity (%) Example 1 Distillation tower 96.4 Comparative Example 4 Autoclave 77.2

[0094] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A catalyst for preparing dialkyl carbonate, characterized in that: The catalyst is an ionic liquid catalyst of binuclear anions and cations; wherein the A core anion is selected from at least one of tetrafluoroborate, hexafluorophosphate, perchlorate, bistrifluoromethanesulfonyl imide, nonafluorobutylsulfonate, pentafluoroethylsulfonate, trifluoromethanesulfonate, and tris(trifluoromethanesulfonyl)methyl, preferably at least one of bistrifluoromethanesulfonyl imide, nonafluorobutylsulfonate, pentafluoroethylsulfonate, and perchlorate; the B core anion is selected from at least one of carbonate, phosphate, sulfate, hydrogen phthalate, phthalate, oxalate, acetate, formate, bromide, fluoride, chloride, and iodide, preferably at least one of carbonate, oxalate, acetate, bromide, chloride, and iodide; the A core cation is a nitrogen heterocyclic quaternary ammonium cation; and the B core cation is an alkali metal cation.

2. The catalyst according to claim 1, characterized in that The nitrogen heterocyclic quaternary ammonium cation is a product of the reaction between a nitrogen heterocyclic crown ether and a halogenated alkane.

3. The catalyst according to claim 2, characterized in that The azacyclic crown ether is selected from at least one of benzylaza-15-crown-5, 1-benzaza-15-crown-5-ether, 1-methoxyaza-15-crown-5, 1-methylaza-18-crown-6, 1-benzaza-18-crown-6, 1-methylaza-21-crown-7, and 1-benzaza-21-crown-7, preferably at least one of 1-methoxyaza-15-crown-5, 1-methylaza-18-crown-6, and 1-benzaza-21-crown-7; And / or, the halogenated alkane is at least one selected from chlorobutane, bromopropane, bromobutane, 2-bromobutane, fluorobutane, iodobutane, and benzyl bromide.

4. The catalyst according to claim 1, characterized in that The alkali metal positive ion is selected from at least one of sodium ion, potassium ion and cesium ion.

5. A method for preparing a catalyst for preparing dialkyl carbonate, comprising: (1) dissolving an azacyclic crown ether in an organic solvent I, adding a halogenated alkane, and reacting; (2) dissolving the product obtained in step (1) in an organic solvent II, adding an ion exchange salt, and reacting to obtain a mononuclear anionic and cationic ionic liquid; (3) dissolving the mononuclear anion and cation ionic liquid obtained in step (2) in alcohol, adding alkali metal salt, and refluxing to obtain the catalyst.

6. The preparation method according to claim 5, characterized in that: In step (1), the azacyclic crown ether is selected from at least one of benzylaza-15-crown ether-5, 1-benzaza-15-crown-5-ether, 1-methoxyaza-15-crown ether-5, 1-methylaza-18-crown ether-6, 1-benzaza-18-crown ether-6, 1-methylaza-21-crown ether-7, and 1-benzaza-21-crown ether-7, preferably at least one of 1-methoxyaza-15-crown ether-5, 1-methylaza-18-crown ether-6, and 1-benzaza-21-crown ether-7; And / or, in step (1), the halogenated alkane is selected from at least one of chlorobutane, bromopropane, bromobutane, 2-bromobutane, fluorobutane, iodobutane, and benzyl bromide; And / or, in step (2), the cation of the ion exchange salt is selected from at least one of lithium, sodium and potassium, and the anion is selected from at least one of tetrafluoroborate, hexafluorophosphate, perchlorate, bistrifluoromethanesulfonyl imide, nonafluorobutylsulfonate, pentafluoroethylsulfonate, trifluoromethanesulfonate and tris(trifluoromethanesulfonyl)methyl, preferably at least one of bistrifluoromethanesulfonyl imide, nonafluorobutylsulfonate, pentafluoroethylsulfonate and perchlorate; And / or, in step (3), the cation of the alkali metal salt is selected from at least one of sodium, potassium, and cesium, and the anion is selected from at least one of carbonate, phosphate, sulfate, hydrogen phthalate, phthalate, oxalate, acetate, formate, bromide, fluoride, chloride, and iodide, preferably at least one of carbonate, oxalate, acetate, bromide, chloride, and iodide.

7. The preparation method according to claim 5, characterized in that: In step (1), the molar ratio of the halogenated alkane to the nitrogen heterocyclic crown ether is 1 to 1.7:1; And / or, in step (2), the molar ratio of the ion exchange salt to the nitrogen heterocyclic crown ether is 2 to 5:1; And / or, in step (3), the molar ratio of the alkali metal salt to the nitrogen heterocyclic crown ether is 1.2 to 3:1 as calculated by cation.

8. The preparation method according to claim 5, characterized in that: In step (1), the organic solvent I is selected from at least one of ethyl acetate, propyl acetate, toluene, xylene, and ethylbenzene, preferably ethyl acetate or toluene; And / or, in step (2), the organic solvent II is selected from at least one of dichloromethane and chloroform; And / or, in step (3), the alcohol is selected from at least one of methanol, ethanol, propanol, isopropanol, 1,3-propylene glycol, and butanol.

9. The preparation method according to claim 5, characterized in that: In step (1), the concentration of the solution obtained by dissolving the azacyclic crown ether in the organic solvent I is 0.2 to 0.7 mol / L; and / or, the concentration of the solution obtained by dissolving the product obtained in step (1) in organic solvent II is 10 wt% to 30 wt%; and / or, in step (2), the concentration of the ion exchange salt solution is 0.4 to 0.9 mol / L; And / or, in step (3), the concentration of the ionic liquid of the mononuclear anion is 10 wt % to 30 wt %.

10. The preparation method according to claim 5, characterized in that: In step (1), the reaction temperature is 45 to 70° C. and the reaction time is 10 to 40 hours; And / or, in step (2), the reaction temperature is 10 to 30° C., and the reaction time is 2 to 5 hours; And / or, in step (3), the reflux temperature is 60-80° C., and the reflux time is 1-4 h.

11. Use of the catalyst according to any one of claims 1 to 4 or the catalyst prepared by the preparation method according to any one of claims 5 to 10, characterized in that: The application is: using dialkyl oxalate as a reaction raw material, carrying out a decarbonylation reaction under the action of the catalyst to prepare dialkyl carbonate.

12. The use according to claim 11, characterized in that The decarbonylation reaction is carried out in a distillation tower. The reaction raw materials and catalyst are fed from the bottom of the distillation tower, mixed, and reacted. The light components generated by the reaction are extracted from the top of the tower by distillation and separated to obtain dialkyl carbonate.

Images