A catalyst for vinylene carbonate synthesis, a preparation method and application thereof

Abstract

The application provides a vinylene carbonate synthesis catalyst and a preparation method and application thereof, and is composed of a nickel-zinc bimetal nanosheet and boron-doped carbon material. The nickel-zinc bimetal two-dimensional nanosheet structure designed in the application can expose more active sites compared with traditional nanoparticles, shorten the mass transfer path, and be beneficial to the diffusion of reactants and products. The nickel and zinc bimetal are uniformly dispersed in the boron-doped carbon matrix in a nanoscale, can utilize the synergistic effect between nickel and zinc and the adjustment effect of nonmetal doping on the electronic structure of carbon material, significantly improve the catalytic activity, the Ni and Zn atoms are closely contacted at an atomic level, the electrons are partially transferred from the Zn to the Ni, the d electron orbital structure of the Ni is finely adjusted, the dissociation adsorption energy of the H2 molecule and the adsorption strength of the reactant molecule are optimized, the hydrogenation / breaking bond reaction is more prone to occur, the boron atoms are doped into the carbon skeleton, the electronic properties of the carbon material are changed, and the catalytic reaction is facilitated.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of vinylene carbonate synthesis, and particularly relates to a vinylene carbonate synthesis catalyst and a preparation method and application thereof. BACKGROUND

[0002] Vinylene carbonate (VC) is an important organic chemical raw material, and has become an ideal lithium ion battery electrolyte film additive due to its unique chemical properties and excellent performance. The dehydrochlorination (HCl) reaction of chloroethylene carbonate (CEC) is a core step for synthesizing vinylene carbonate (VC). An organic base (such as triethylamine) is generally used as a catalyst or dehalogenating agent in the process, and the homogeneous system has problems such as many side reactions, low product selectivity, a large amount of waste liquid containing chlorine, and the catalyst cannot be recovered, which is not only not friendly to the environment, but also increases the post-treatment cost.

[0003] In order to overcome these drawbacks, heterogeneous catalysis technology is considered as an ideal alternative. However, the existing heterogeneous catalysts still face many challenges in research and application: first, the activity site density and utilization efficiency of the catalyst are often insufficient, the traditional nanoparticle structure is easy to agglomerate, leading to a decrease in activity, and the mass transfer resistance of the reactants and products is large; second, the specific activation mechanism of the C-Cl bond is not deep enough, and there is a lack of stable active site design that can efficiently and accurately activate the bond, thereby limiting the simultaneous improvement of the reaction rate and selectivity; finally, from the perspective of production process, most studies are still limited to batch reactors, which are difficult to match with efficient and energy-saving continuous production processes, thereby restricting the potential of large-scale industrial application.

[0004] Therefore, further improvement and development are needed. SUMMARY

[0005] The application provides a vinylene carbonate synthesis catalyst and a preparation method and application thereof, and a specific implementation manner is as follows:

[0006] The application provides a vinylene carbonate synthesis catalyst, which is composed of nickel-zinc bimetallic nanosheets and boron-doped carbon material.

[0007] The application provides a preparation method of a vinylene carbonate synthesis catalyst.

[0008] The boron source is boric acid.

[0009] The carbon source is one or more of glucose, sucrose and citric acid, and the surfactant is one or more of sodium dodecyl sulfate (SDS), sodium diisooctyl sulfosuccinate (AOT), cetyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP).

[0010] The molar ratio of the carbon source to the boron source is 2-5:1.

[0011] The nickel source is nickel nitrate hexahydrate, the zinc source is zinc nitrate hexahydrate, and the amount of the surfactant is 10%-50% of the total mass of the nickel nitrate hexahydrate and the zinc nitrate hexahydrate.

[0012] The molar ratio of the nickel nitrate hexahydrate to the zinc nitrate hexahydrate is 1-3:1.

[0013] The vinylidene carbonate synthesis catalyst is prepared according to the following steps:

[0014] S1, precursor synthesis: dissolve nickel nitrate hexahydrate and zinc nitrate hexahydrate in deionized water, denoted as solution A, dissolve the carbon source, the boron source and the surfactant in deionized water, denoted as solution B, drop solution A into solution B and stir, keep at 150-180℃ for 8-12 hours, after cooling, centrifuge and wash the precipitate and dry to obtain the precursor;

[0015] S2, calcination: raise the precursor obtained in step S1 to 450-550℃ at a temperature rising speed of 1-3℃ / min and calcine for 2-3 hours;

[0016] S3, reduction: after cooling the product calcined in step S2 to room temperature, pass in H2 / Ar, reduce for 1.5-3 hours and cool to room temperature.

[0017] The application further provides a use of the vinylidene carbonate synthesis catalyst, which is used as a catalyst for generating vinylidene carbonate through catalytic dehydrochlorination of chloroethylene carbonate.

[0018] The steps for generating vinylidene carbonate through catalytic dehydrochlorination of chloroethylene carbonate are as follows:

[0019] (1) catalyst filling: fill the vinylidene carbonate synthesis catalyst into a fixed bed reactor to form a catalyst bed in the fixed bed reactor;

[0020] (2) catalytic reaction: pass chloroethylene carbonate into the fixed bed reactor, the chloroethylene carbonate enters the catalyst bed, the catalytic reaction temperature is 200-400℃, the chloroethylene carbonate is catalytically removed of hydrogen chloride, and the crude vinylidene carbonate is collected, and the tail gas is absorbed by water and lye;

[0021] (3) Distillation of crude product: the crude product of vinylene carbonate obtained in step (2) is subjected to distillation at an oil temperature of 55-75℃ and a vacuum degree of 300-500 Pa to obtain a distillation product;

[0022] (4) Distillation: a plurality of batches of the distillation product obtained in step (3) are collected and mixed, and subjected to distillation to obtain a distillation product.

[0023] Thanks to the above technical solutions, the present application has the following beneficial technical effects:

[0024] 1. The two-dimensional nanosheet structure designed in the present application can expose more active sites, shorten the mass transfer path, and facilitate the diffusion of reactants and products, compared with traditional nanoparticles. The nickel (Ni) and zinc (Zn) bimetal is uniformly dispersed in the boron (B) doped carbon matrix at the nanoscale, which can utilize the synergistic effect between the metals and the adjustment effect of non-metal doping on the electronic structure of carbon materials, significantly improve the catalytic activity, and make the Ni and Zn atoms closely contact at the atomic level. The partial transfer of electrons from Zn to Ni fine-tunes the d electron orbital structure of Ni, optimizes the dissociation adsorption energy of H2 molecules and the adsorption strength of reactant molecules, and makes it easier to occur hydrogenation / breaking reaction. The boron atom doped into the carbon skeleton can change the electronic properties of carbon materials, which is beneficial to the catalytic reaction.

[0025] 2. The boron element is introduced into the catalyst for the synthesis of vinylene carbonate in the present application. The boron species can act as a Lewis acid site and interact with the lone pair of electrons of the chlorine atom in the reactant to activate the C-Cl bond and promote the dehydrochlorination reaction. The carbon matrix can effectively prevent the agglomeration of metal nanoparticles and improve the stability and service life of the catalyst.

[0026] 3. The present application uses a fixed bed reactor to realize continuous production, which can greatly reduce the downtime and equipment cleaning operations in the production process compared with the traditional batch production method, improve the utilization rate and production efficiency of the equipment, realize efficient and stable production of vinylene carbonate, and meet the needs of large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a schematic diagram of the micro-morphology of the catalyst for the synthesis of vinylene carbonate of the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0029] A catalyst for vinylene carbonate synthesis is composed of nickel-zinc bimetal nanosheets and boron-doped carbon material. Figure 1 The micro-morphology of the catalyst for vinylene carbonate synthesis is shown in the figure.

[0030] The two-dimensional nanosheet structure designed in the application can expose more active sites compared with traditional nanoparticles, shorten the mass transfer path, and facilitate the diffusion of reactants and products. The nickel (Ni) and zinc (Zn) bimetal is uniformly dispersed in the boron (B) doped carbon matrix at the nanoscale, which can utilize the synergistic effect between metals and the adjustment effect of non-metal doping on the electronic structure of carbon material, significantly improve the catalytic activity, and the boron atom doped into the carbon skeleton can change the electronic properties of carbon material, which is beneficial to the catalytic reaction.

[0031] The application provides a preparation method of a catalyst for vinylene carbonate synthesis.

[0032] The boron source is boric acid; the carbon source is one or more of glucose, sucrose and citric acid; the surfactant is one or more of sodium dodecyl sulfate, sodium diisooctyl sulfosuccinate, cetyltrimethylammonium bromide and polyvinylpyrrolidone; the nickel source is nickel nitrate hexahydrate; the zinc source is zinc nitrate hexahydrate; and the amount of the surfactant is 10% to 50% of the total mass of the nickel nitrate hexahydrate and the zinc nitrate hexahydrate.

[0033] The boron element is introduced into the catalyst for vinylene carbonate synthesis, the boron species can act as a Lewis acid site and interact with the lone pair of electrons of the chlorine atom in the reactant to activate the C-Cl bond and promote the dehydrochlorination reaction. The carbon matrix can effectively prevent the agglomeration of metal nanoparticles and improve the stability and recycling life of the catalyst.

[0034] The application also provides an application of the catalyst for vinylene carbonate synthesis, which uses the catalyst for vinylene carbonate synthesis as a catalyst for the catalytic dehydrochlorination reaction of chloroethylene carbonate to generate vinylene carbonate.

[0035] The steps of the catalytic dehydrochlorination reaction of chloroethylene carbonate to generate vinylene carbonate are as follows:

[0036] (1) Catalyst filling: the catalyst for vinylene carbonate synthesis is loaded into a fixed bed reactor to form a catalyst bed in the fixed bed reactor;

[0037] (2) Catalytic reaction: chloroethylene carbonate is introduced into the fixed bed reactor, and the chloroethylene carbonate enters the catalyst bed layer, the catalytic reaction temperature is 200-400 DEG C, the hydrogen chloride in the chloroethylene carbonate is removed by catalytic reaction, and the crude product of vinylene carbonate is collected, and the tail gas is absorbed by water and lye;

[0038] (3) Crude product distillation: the crude product of vinylene carbonate obtained in step (2) is distilled at an oil temperature of 55-75 DEG C, and a vacuum degree of 300-500 Pa, to obtain a distillation product;

[0039] (4) Rectification: collect and mix the distillation products obtained in step (3) to obtain a rectification product.

[0040] The application realizes continuous production by using a fixed bed reactor, compared with the traditional batch production mode, the downtime and equipment cleaning operation in the production process can be greatly reduced, the utilization rate and production efficiency of the equipment are improved, the efficient and stable production of vinylene carbonate is realized, and the demand of large-scale industrial production is met.

[0041] Example 1

[0042] The embodiment provides a catalyst for synthesizing vinylene carbonate, and the specific steps are as follows:

[0043] S1, precursor synthesis: 0.01 mol of nickel nitrate hexahydrate and 0.01 mol of zinc nitrate hexahydrate are dissolved in deionized water, denoted as solution A, 0.1 mol of glucose, 0.05 mol of boric acid and 0.59 g of PVP are dissolved in deionized water, denoted as solution B, solution A is slowly added to solution B and magnetically stirred for 30 min, and then transferred to a polytetrafluoroethylene autoclave, and kept at 180 DEG C for 12 hours. After cooling, the precipitate is washed with deionized water and anhydrous ethanol by centrifugation and dried in a vacuum oven at 60 DEG C for 10 hours.

[0044] S2, calcination: 5 g of the precursor is placed in a tube furnace, and the temperature is raised to 500 DEG C at a rate of 2 DEG C / min and kept for 2 hours.

[0045] S3, reduction: after cooling to room temperature, 10% H2 / Ar is introduced into the tube furnace, and the temperature is raised to 400 DEG C and kept for 1.5 hours, and then naturally cooled to room temperature.

[0046] The above catalyst is used as a catalyst for the preparation of vinylene carbonate, and the specific steps are as follows:

[0047] (1) Catalyst filling: 2 g of the catalyst for synthesizing vinylene carbonate is loaded into a fixed bed reactor to form a catalyst bed layer in the fixed bed reactor;

[0048] (2) Catalytic reaction: adjust the temperature in the tubular reactor to 400°C (catalytic reaction temperature), start the raw material feeding pump, and pass the chloroethylene carbonate into the fixed bed reactor. The feeding flow rate of the chloroethylene carbonate is 0.5 mL / min, and the chloroethylene carbonate catalytically removes hydrogen chloride. Every 0.5 h, collect the crude vinylene carbonate product and weigh it, continuously detect the conversion rate of the chloroethylene carbonate and the content of each impurity, and observe the activity of the catalyst. The tail gas is absorbed by water and lye.

[0049] (3) Crude product distillation: distill the crude vinylene carbonate product obtained in step S2 at an oil temperature of 65°C using a high vacuum pump to quickly distill the product at a vacuum degree of 400 Pa to obtain a distillation product.

[0050] (4) Rectification: collect and mix the distillation products obtained in step S3 in batches, and rectify them using a thorn-shaped rectification column. The rectification conditions are as follows: oil temperature 65°C, kettle temperature 60°C, top temperature 35°C, and vacuum degree 400 Pa. The rectification product is obtained, and the vinylene carbonate product with a content of >99.99% is collected.

[0051] In this embodiment, the conversion rate of the chloroethylene carbonate (CEC) is 98.6%, the selectivity of the vinylene carbonate (VC) is 80.7%, and the yield is 71.6%.

[0052] Example 2

[0053] This embodiment provides a catalyst for synthesizing vinylene carbonate, and the specific steps are as follows:

[0054] S1, precursor synthesis: dissolve 0.01 mol of nickel nitrate hexahydrate and 0.01 mol of zinc nitrate hexahydrate in deionized water, denoted as solution A; dissolve 0.1 mol of sucrose, 0.05 mol of boric acid, and 0.59 g of SDS in deionized water, denoted as solution B; slowly add solution A to solution B and magnetically stir for 30 min, then transfer to a polytetrafluoroethylene autoclave, and keep at 180°C for 12 hours. After cooling, the precipitate is washed with deionized water and anhydrous ethanol by centrifugation and dried in a vacuum oven at 60°C for 10 hours.

[0055] S2, calcination: place 5 g of the precursor into a tubular furnace, and raise the temperature to 500°C at a rate of 2°C / min and keep for 2 hours.

[0056] S3, reduction: after cooling to room temperature, pass 10% H2 / Ar into the tubular furnace, and reduce at 400°C for 1.5 hours, and naturally cool to room temperature.

[0057] This embodiment uses the above-mentioned catalyst as the catalyst for the preparation of vinylene carbonate, and the specific steps are as follows:

[0058] (1) Catalyst filling: 2 g of catalyst for vinyl carbonate synthesis was loaded into a fixed bed reactor to form a catalyst bed in the fixed bed reactor;

[0059] (2) Catalytic reaction: the temperature in the tube reactor was adjusted to 400°C (catalytic reaction temperature), the raw material feeding pump was turned on, and chloroethylene carbonate was introduced into the fixed bed reactor. The feeding flow rate of chloroethylene carbonate was 0.5 mL / min, and the hydrogen chloride was removed by catalytic reaction. Every 0.5 h, the crude vinyl carbonate was collected and weighed, the conversion rate of chloroethylene carbonate and the content of each impurity were continuously detected, the catalyst activity was observed, and the tail gas was absorbed by water and lye.

[0060] (3) Crude product distillation: the crude vinyl carbonate obtained in step S2 was quickly distilled at an oil temperature of 65°C using a high vacuum pump, and the vacuum degree was 400 Pa to obtain the distillation product.

[0061] (4) Distillation: multiple batches of distillation products obtained in step S3 were collected and mixed, and then subjected to distillation using a thorn-shaped distillation column. The distillation conditions were as follows: oil temperature 65°C, kettle temperature 60°C, top temperature 35°C, and vacuum degree 400 Pa. The distillation product was obtained, and the vinyl carbonate product with a content of >99.99% was collected.

[0062] In this embodiment, the conversion rate of chloroethylene carbonate (CEC) was 99.2%, the selectivity of vinyl carbonate (VC) was 82.4%, and the yield was 75.2%.

[0063] Example 3

[0064] This embodiment provides a catalyst for vinyl carbonate synthesis, and the specific steps are as follows:

[0065] S1, precursor synthesis: 0.01 mol of nickel nitrate hexahydrate and 0.01 mol of zinc nitrate hexahydrate were dissolved in deionized water, denoted as solution A. 0.1 mol of glucose, 0.05 mol of boric acid, and 0.59 g of AOT were dissolved in deionized water, denoted as solution B. Solution A was slowly added to solution B and magnetically stirred for 30 min, and then transferred to a polytetrafluoroethylene autoclave. It was kept at 180°C for 12 hours. After cooling, the precipitate was washed with deionized water and anhydrous ethanol by centrifugation and dried in a vacuum oven at 60°C for 10 hours.

[0066] S2, calcination: 5 g of the precursor was placed in a tube furnace, and the temperature was raised to 500°C at a rate of 2°C / min and kept for 2 hours.

[0067] S3, reduction: after cooling to room temperature, 10% H2 / Ar was introduced into the tube furnace, and reduction was carried out at 400°C for 1.5 hours, and then naturally cooled to room temperature.

[0068] The catalyst is used as a catalyst for preparing vinylene carbonate, and the specific steps are as follows:

[0069] (1) Catalyst filling: 2 g of the catalyst for synthesizing vinylene carbonate is loaded into a fixed bed reactor to form a catalyst bed in the fixed bed reactor;

[0070] (2) Catalytic reaction: The temperature in the tubular reactor is adjusted to 400°C (catalytic reaction temperature), the raw material feeding pump is started, and chloroethylene carbonate is fed into the fixed bed reactor, with a feeding flow rate of 0.5 mL / min. The chloroethylene carbonate is catalytically removed to produce hydrogen chloride, and the crude vinylene carbonate is collected and weighed every 0.5 h. The conversion rate of chloroethylene carbonate and the content of each impurity are continuously detected, the catalyst activity is observed, and the tail gas is absorbed by water and lye;

[0071] (3) Crude product distillation: The crude vinylene carbonate obtained in step S2 is rapidly distilled at an oil temperature of 65°C using a high vacuum pump, with a vacuum degree of 400 Pa, to obtain a distillation product;

[0072] (4) Rectification: A plurality of distillation products obtained in step S3 are collected and mixed, and are subjected to rectification using a thorn-shaped rectification column. The rectification conditions are as follows: oil temperature 65°C, kettle temperature 60°C, top temperature 35°C, and vacuum degree 400 Pa. A rectification product is obtained, and a vinylene carbonate product with a content of >99.99% is collected.

[0073] In this embodiment, the conversion rate of chloroethylene carbonate (CEC) is 97.3%, the selectivity of vinylene carbonate (VC) is 78.5%, and the yield is 70.3%.

[0074] Example 4

[0075] The embodiment provides a catalyst for synthesizing vinylene carbonate, and the specific steps are as follows:

[0076] S1, precursor synthesis: 0.01 mol of nickel nitrate hexahydrate and 0.01 mol of zinc nitrate hexahydrate are dissolved in deionized water, denoted as solution A. 0.1 mol of citric acid, 0.05 mol of boric acid, and 0.59 g of CTAB are dissolved in deionized water, denoted as solution B. Solution A is slowly added to solution B and magnetically stirred for 30 min, and then transferred to a polytetrafluoroethylene autoclave. It is kept at 180°C for 12 hours. After cooling, the precipitate is washed with deionized water and anhydrous ethanol by centrifugation and dried in a vacuum oven at 60°C for 10 hours.

[0077] S2, calcination: 5 g of the precursor is placed in a tubular furnace, which is raised to 500°C at a rate of 2°C / min and kept for 2 hours.

[0078] S3, Reduction: After cooling to room temperature, 10% H2 / Ar was introduced into the tube furnace, and reduction was carried out at 400°C for 1.5 hours, and then the temperature was naturally cooled to room temperature.

[0079] The above catalyst was used as a catalyst for the preparation of vinylene carbonate, and the specific steps were as follows:

[0080] (1) Catalyst filling: 2 g of the catalyst for vinylene carbonate synthesis was loaded into a fixed bed reactor to form a catalyst bed in the fixed bed reactor;

[0081] (2) Catalytic reaction: The temperature in the tube reactor was adjusted to 400°C (catalytic reaction temperature), the raw material feeding pump was opened, and chloroethylene carbonate was introduced into the fixed bed reactor. The feeding flow rate of chloroethylene carbonate was 0.5 mL / min, and the hydrogen chloride in chloroethylene carbonate was catalytically removed. Every 0.5 h, the crude vinylene carbonate was collected and weighed, the conversion rate of chloroethylene carbonate and the content of each impurity were continuously detected, the catalyst activity was observed, and the tail gas was absorbed by water and lye;

[0082] (3) Crude product distillation: The crude vinylene carbonate obtained in step S2 was quickly distilled at an oil temperature of 65°C using a high vacuum pump, and the vacuum degree was 400 Pa to obtain a distilled product;

[0083] (4) Rectification: A plurality of batches of distilled products obtained in step S3 were collected and mixed, and rectification was carried out using a thorn-shaped rectification column. The rectification conditions were as follows: oil temperature 65°C, kettle temperature 60°C, top temperature 35°C, and vacuum degree 400 Pa. A rectified product was obtained, and a vinylene carbonate product with a content of >99.99% was collected.

[0084] In this embodiment, the conversion rate of chloroethylene carbonate (CEC) was 99.1%, the selectivity of vinylene carbonate (VC) was 81.5%, and the yield was 72.7%.

[0085] Example 5

[0086] This embodiment provides a catalyst for vinylene carbonate synthesis, and the specific steps are as follows:

[0087] S1, Precursor synthesis: 0.02 mol of nickel nitrate hexahydrate and 0.01 mol of zinc nitrate hexahydrate were dissolved in deionized water, denoted as solution A. 0.15 mol of sucrose, 0.05 mol of boric acid, and 1.76 g of PVP were dissolved in deionized water, denoted as solution B. Solution A was slowly added to solution B and magnetically stirred for 30 min, and then transferred to a polytetrafluoroethylene autoclave. It was kept at 180°C for 12 hours. After cooling, the precipitate was washed with deionized water and anhydrous ethanol by centrifugation and dried in a vacuum oven at 60°C for 10 hours.

[0088] S2, Calcination: 5 g of the precursor was put into a tube furnace, and raised to 500°C at a rate of 2°C / min and maintained for 2 hours.

[0089] S3, Reduction: After cooling to room temperature, 10% H2 / Ar was introduced into the tube furnace, and reduced at 400°C for 1.5 hours, and naturally cooled to room temperature.

[0090] The above catalyst was used as a catalyst for the preparation of vinylene carbonate, and the specific steps were as follows:

[0091] (1) Catalyst filling: 5 g of the catalyst for the synthesis of vinylene carbonate was loaded into a fixed bed reactor, and a catalyst bed was formed in the fixed bed reactor;

[0092] (2) Catalytic reaction: The temperature in the tube reactor was adjusted to 400°C (catalytic reaction temperature), the raw material feeding pump was turned on, and chloroethylene carbonate was introduced into the fixed bed reactor. The feeding flow rate of chloroethylene carbonate was 1 mL / min, and the hydrogen chloride was catalytically removed. Every 0.5 h, the crude vinylene carbonate was collected and weighed, the conversion rate of chloroethylene carbonate and the content of each impurity were continuously detected, the activity of the catalyst was observed, and the tail gas was absorbed by water and alkali;

[0093] (3) Crude product distillation: The crude vinylene carbonate obtained in step S2 was quickly distilled at an oil temperature of 65°C using a high vacuum pump, and the vacuum degree was 400 Pa, to obtain a distilled product;

[0094] (4) Rectification: A plurality of batches of distilled products obtained in step S3 were collected and mixed, and rectified using a thorn-shaped rectification column. The rectification conditions were: oil temperature 65°C, kettle temperature 60°C, top temperature 35°C, and vacuum degree 400 Pa. The rectification product was obtained, and the content of the vinylene carbonate product was >99.99%.

[0095] In this example, the conversion rate of chloroethylene carbonate (CEC) was 98.6%, the selectivity of vinylene carbonate (VC) was 80.8%, and the yield was 73.3%.

[0096] Example 6

[0097] This example provides a catalyst for the synthesis of vinylene carbonate, and the specific steps are as follows:

[0098] S1, precursor synthesis: 0.02 mol of nickel nitrate hexahydrate, 0.01 mol of zinc nitrate hexahydrate were dissolved in deionized water, denoted as solution A, 0.15 mol of glucose, 0.05 mol of boric acid and 1.76 g of SDS were dissolved in deionized water, denoted as solution B, solution A was slowly added to solution B and magnetically stirred for 30 min, then transferred to a polytetrafluoroethylene autoclave, kept at 180°C for 12 hours. After cooling, the precipitate was washed with deionized water and anhydrous ethanol by centrifugation and dried in a vacuum oven at 60°C for 10 hours.

[0099] S2, calcination: 5 g of the precursor was placed in a tube furnace, raised to 500°C at 2°C / min and kept for 2 hours.

[0100] S3, reduction: after cooling to room temperature, 10% H2 / Ar was introduced into the tube furnace, reduced at 400°C for 1.5 hours, and naturally cooled to room temperature.

[0101] The above catalyst was used as the catalyst for the preparation of vinylene carbonate, and the specific steps were as follows:

[0102] (1) Catalyst filling: 5 g of the catalyst for vinylene carbonate synthesis was loaded into a fixed bed reactor, and a catalyst bed was formed in the fixed bed reactor;

[0103] (2) Catalytic reaction: adjust the temperature in the tube reactor to 400°C (catalytic reaction temperature), start the raw material feeding pump, introduce chloroethylene carbonate into the fixed bed reactor, the feeding flow rate of chloroethylene carbonate is 1 mL / min, the hydrogen chloride in chloroethylene carbonate is catalytically removed, collect the crude vinylene carbonate every 0.5 h and weigh it, continuously detect the conversion rate of chloroethylene carbonate and the content of each impurity, observe the activity of the catalyst, and the tail gas is absorbed by water and lye;

[0104] (3) Crude product distillation: the crude vinylene carbonate obtained in step S2 was quickly distilled at an oil temperature of 65°C using a high vacuum pump, the vacuum degree was 400 Pa, and the distilled product was obtained;

[0105] (4) Rectification: collect and mix the distilled products obtained in step S3 in batches, and rectify them using a thorn-shaped rectification column, the rectification conditions are: oil temperature 65°C, kettle temperature 60°C, top temperature 35°C, vacuum degree 400 Pa, to obtain the rectified product, and collect the vinylene carbonate product with a content of >99.99%.

[0106] In this example, the conversion rate of chloroethylene carbonate (CEC) was 98.5%, the selectivity of vinylene carbonate (VC) was 81.2%, and the yield was 74.3%.

[0107] Example 7

[0108] The embodiment provides a catalyst for vinylene carbonate synthesis, and the specific steps are as follows:

[0109] S1, precursor synthesis: 0.02 mol of nickel nitrate hexahydrate and 0.01 mol of zinc nitrate hexahydrate are dissolved in deionized water, denoted as solution A; 0.15 mol of citric acid, 0.05 mol of boric acid and 1.76 g of AOT are dissolved in deionized water, denoted as solution B; solution A is slowly added to solution B and magnetically stirred for 30 min, and then transferred to a polytetrafluoroethylene autoclave; and the mixture is kept at 180 DEG C for 12 hours. After cooling, the precipitate is washed with deionized water and anhydrous ethanol by centrifugation and dried in a vacuum oven at 60 DEG C for 10 hours.

[0110] S2, calcination: 5 g of the precursor is placed in a tube furnace, and the temperature is raised to 500 DEG C at a rate of 2 DEG C / min and kept for 2 hours.

[0111] S3, reduction: after cooling to room temperature, 10% H2 / Ar is introduced into the tube furnace, and the temperature is kept at 400 DEG C for 1.5 hours, and then the temperature is naturally cooled to room temperature.

[0112] The catalyst is used as a catalyst for the preparation of vinylene carbonate, and the specific steps are as follows:

[0113] (1) catalyst filling: 5 g of the catalyst for vinylene carbonate synthesis is loaded into a fixed bed reactor, and a catalyst bed is formed in the fixed bed reactor;

[0114] (2) catalytic reaction: the temperature in the tube reactor is adjusted to 400 DEG C (catalytic reaction temperature), the raw material feeding pump is started, chloroethylene carbonate is introduced into the fixed bed reactor, the feeding flow rate of chloroethylene carbonate is 1 mL / min, and the hydrogen chloride in chloroethylene carbonate is catalytically removed; crude vinylene carbonate is collected and weighed every 0.5 h, the conversion rate of chloroethylene carbonate and the content of various impurities are continuously detected, the activity of the catalyst is observed, and the tail gas is absorbed by water and lye;

[0115] (3) crude product distillation: the crude vinylene carbonate obtained in step S2 is rapidly distilled at an oil temperature of 65 DEG C by using a high vacuum pump, the vacuum degree is 400 Pa, and the distillation product is obtained;

[0116] (4) rectification: a plurality of batches of the distillation product obtained in step S3 are collected and mixed, and are subjected to rectification by using a thorn-shaped rectification column; the rectification conditions are as follows: the oil temperature is 65 DEG C, the kettle temperature is 60 DEG C, the top temperature is 35 DEG C, and the vacuum degree is 400 Pa; the rectification product is obtained, and the vinylene carbonate product with a content of >99.99% is collected.

[0117] In the embodiment, the conversion rate of chloroethylene carbonate (CEC) is 97.7%, the selectivity of vinylene carbonate (VC) is 82.4%, and the yield is 72.9%.

[0118] Example 8

[0119] The present embodiment provides a catalyst for vinylene carbonate synthesis, the specific steps are as follows:

[0120] S1, precursor synthesis: dissolve 0.02 mol of nickel nitrate hexahydrate and 0.01 mol of zinc nitrate hexahydrate in deionized water, denoted as solution A, dissolve 0.15 mol of glucose, 0.05 mol of boric acid and 1.76 g of CTAB in deionized water, denoted as solution B, slowly add solution A to solution B and magnetically stir for 30 min, then transfer to a polytetrafluoroethylene autoclave, keep at 180℃ for 12 hours. After cooling, the precipitate is washed with deionized water and anhydrous ethanol by centrifugation and dried in a vacuum oven at 60℃ for 10 hours.

[0121] S2, calcination: put 5 g of the precursor into a tube furnace, increase to 500℃ at 2℃ / min and keep for 2 hours.

[0122] S3, reduction: after cooling to room temperature, introduce 10% H2 / Ar into the tube furnace, reduce at 400℃ for 1.5 hours, and naturally cool to room temperature.

[0123] The above catalyst is used as the catalyst for the preparation of vinylene carbonate, the specific steps are as follows:

[0124] (1) Catalyst filling: 5 g of the catalyst for vinylene carbonate synthesis is loaded into a fixed bed reactor to form a catalyst bed in the fixed bed reactor;

[0125] (2) Catalytic reaction: adjust the temperature in the tube reactor to 400℃ (catalytic reaction temperature), start the raw material feeding pump, introduce chloroethylene carbonate into the fixed bed reactor, the feeding flow rate of chloroethylene carbonate is 1 mL / min, the hydrogen chloride in chloroethylene carbonate is catalytically removed, collect the crude vinylene carbonate every 0.5 h and weigh it, continuously detect the conversion rate of chloroethylene carbonate and the content of each impurity, observe the catalyst activity, and the tail gas is absorbed by water and lye;

[0126] (3) Crude product distillation: the crude vinylene carbonate obtained in step S2 is quickly distilled at an oil temperature of 65℃ using a high vacuum pump, the vacuum degree is 400 Pa, and the distillation product is obtained;

[0127] (4) Rectification: collect and mix the distillation products obtained in step S3 in batches, and rectify using a thorn-shaped rectification column, the rectification conditions are: oil temperature 65℃, kettle temperature 60℃, top temperature 35℃, vacuum degree 400 Pa, to obtain the rectification product, and collect the vinylene carbonate product with a content of >99.99%.

[0128] In this embodiment, the conversion rate of chloroethylene carbonate (CEC) is 96.8%, the selectivity of vinylene carbonate (VC) is 83.1%, and the yield is 73.5%.

[0129] Example 9

[0130] This embodiment provides a catalyst for synthesizing vinylene carbonate, and the specific steps are as follows:

[0131] S1, precursor synthesis: dissolve 0.03 mol of nickel nitrate hexahydrate and 0.01 mol of zinc nitrate hexahydrate in deionized water, denoted as solution A; dissolve 0.25 mol of glucose, 0.05 mol of boric acid, and 2.34 g of PVP in deionized water, denoted as solution B; slowly add solution A to solution B and magnetically stir for 30 min, then transfer to a polytetrafluoroethylene autoclave, and keep at 180°C for 12 hours. After cooling, the precipitate is washed with deionized water and anhydrous ethanol by centrifugation and dried in a vacuum oven at 60°C for 10 hours.

[0132] S2, calcination: place 5 g of the precursor into a tube furnace, increase the temperature to 500°C at a rate of 2°C / min, and keep for 2 hours.

[0133] S3, reduction: after cooling to room temperature, introduce 10% H2 / Ar into the tube furnace, and reduce at 400°C for 1.5 hours, and naturally cool to room temperature.

[0134] The above catalyst is used as a catalyst for the preparation of vinylene carbonate, and the specific steps are as follows:

[0135] (1) Catalyst filling: 2 g of the catalyst for synthesizing vinylene carbonate is loaded into a fixed bed reactor to form a catalyst bed in the fixed bed reactor;

[0136] (2) Catalytic reaction: adjust the temperature in the tube reactor to 400°C (catalytic reaction temperature), start the raw material feeding pump, introduce chloroethylene carbonate into the fixed bed reactor, the feeding flow rate of chloroethylene carbonate is 0.5 mL / min, catalytically remove hydrogen chloride from chloroethylene carbonate, collect and weigh the crude vinylene carbonate every 0.5 h, continuously detect the conversion rate of chloroethylene carbonate and the content of each impurity, observe the activity of the catalyst, and the tail gas is absorbed by water and alkali;

[0137] (3) Crude product distillation: the crude vinylene carbonate obtained in step S2 is quickly distilled at an oil temperature of 75°C using a high vacuum pump, the vacuum degree is 500 Pa, and the distilled product is obtained;

[0138] (4) Rectification: Collect and mix the distillation products obtained in step S3 in batches, and rectify using a thorn-shaped rectification column, with the rectification conditions being: oil temperature 75°C, kettle temperature 65°C, top temperature 37°C, vacuum degree 500 Pa, to obtain a rectification product, and collect a vinylene carbonate product with a content >99.99%.

[0139] In this embodiment, the conversion rate of chloroethylene carbonate (CEC) is 98.5%, the selectivity of vinylene carbonate (VC) is 81.2%, and the yield is 73.6%.

[0140] The reaction results of Examples 1-9 are shown in Table 1 below.

[0141] Table 1: Statistical results of vinylene carbonate reaction of Examples 1-9

[0142]

[0143] The 9 examples are divided into three groups for clear comparative analysis:

[0144] The first group (Examples 1-4): fixed Ni:Zn = 1:1, carbon source: boron source = 2:1, catalyst loading 2g, feed flow rate 0.5 mL / min. The only variable is the type of surfactant and carbon source.

[0145] The second group (Examples 5-8): fixed Ni:Zn = 2:1, carbon source: boron source = 3:1, catalyst loading 5g, feed flow rate 1 mL / min. The only variable is the type of surfactant and carbon source.

[0146] The third group (Example 9): fixed Ni:Zn = 3:1, carbon source: boron source = 5:1, catalyst loading 2g, feed flow rate 1 mL / min. Different from the examples are also the temperature and vacuum degree of distillation and rectification when preparing vinylene carbonate.

[0147] The surfactant is the key template for the formation of two-dimensional nanosheet structure, and its type directly determines the morphology, thickness and specific surface area of the nanosheet, thus significantly affecting the catalytic performance. SDS (sodium dodecyl sulfate) Example 2 (SDS): achieved the highest conversion (99.2%) and the highest yield (75.2%) in this group and even in all examples. Example 6 (SDS): also achieved the highest selectivity (81.2%) and excellent yield (74.3%) in the second group. SDS as an anionic surfactant is more conducive to the formation of regular, ultra-thin and well-dispersed nanosheet structure, exposing the most active sites and providing the most optimal mass transfer path. Sub-optimal performance: PVP (polyvinylpyrrolidone) and CTAB (cetyltrimethylammonium bromide). PVP (Examples 1, 5): stable performance, conversion and yield are at the upper-middle level. PVP as a non-ionic polymer surfactant has good dispersion and stabilization effect, and can form reliable nanostructure. The catalyst using CTAB shows high selectivity, relatively low conversion. The selectivity of Examples 4 and 8 is 81.5% and 83.1% respectively (the highest in all). This indicates that CTAB may form a catalyst with more regular channel structure or better optimized acid sites, inhibiting side reactions, but may slightly sacrifice part of the reaction rate. Example 9 confirms that the designs within the other protection scope of the present application all have good effects.

[0148] Comparing the first group and the second group, in addition to the metal ratio, the catalyst loading and the feed flow rate are also changed at the same time, that is, the amount of raw material treated per hour per unit catalyst is changed, although the space velocity of the second group is lower and the Ni content is higher, but its average conversion rate does not significantly surpass the first group, even slightly fluctuates. This may be because at higher temperatures, too long contact time or too much Ni site may cause slight over-reaction or carbon deposition, which in turn limits the further improvement of the conversion rate. However, the selectivity of the second group is generally higher than that of the first group (comparative example 1 vs. example 5, example 2 vs. example 6, etc.), which proves that the specific Ni / Zn ratio helps to improve the product selectivity. The present application relates to a catalyst for synthesizing vinylene carbonate, which is prepared by using nickel nitrate hexahydrate, zinc nitrate hexahydrate, a carbon source, a surfactant, and a boron source as raw materials, and adjusting the surfactant to prepare nickel-zinc bimetallic nanosheets and boron-doped carbon materials. The nickel (Ni) and zinc (Zn) bimetal is uniformly dispersed in the boron (B) doped carbon matrix in nanometer scale, which can utilize the synergistic effect between the metals and the adjustment effect of non-metal doping on the electronic structure of the carbon material, and significantly improve the catalytic activity. The boron atom doped into the carbon skeleton can change the electronic properties of the carbon material (such as improving the electrical conductivity and inducing charge redistribution), which is beneficial to the catalytic reaction. The boron species can act as Lewis acid sites and interact with the lone pair electrons of the chlorine atoms in the reactant to activate the C-Cl bond and promote the dehydrochlorination reaction. The carbon matrix can effectively prevent the agglomeration of metal nanoparticles and improve the stability and recycling life of the catalyst.

[0149] From the results of the selection of carbon sources (glucose, sucrose, citric acid), the three show mutual highs and lows, but the difference is not significant, and the three carbon sources can effectively form boron-doped carbon matrix.

[0150] Comparative Example 1

[0151] Compared with Example 1, the only difference is that the catalyst does not add zinc nitrate hexahydrate, and other conditions are the same.

[0152] Comparative Example 2

[0153] Compared with Example 1, the only difference is that the catalyst does not add nickel nitrate hexahydrate, and other conditions are the same.

[0154] Comparative Example 3

[0155] Compared with Example 1, the only difference is that the catalyst adds 0.01 mol of nickel nitrate hexahydrate and 0.02 mol of zinc nitrate hexahydrate, and other conditions are the same.

[0156] Comparative Example 4

[0157] Compared with Example 1, the only difference is that the catalyst does not add a surfactant, and other conditions are the same.

[0158] The reaction results of Comparative Examples 1-4 are shown in Table 2 below.

[0159] Table 2 Statistical results of the reaction of ethylene carbonate in Example 1 and Comparative Examples 1-4

[0160]

[0161] The catalyst is prepared by a hydrothermal method, and the nickel (Ni) and zinc (Zn) are not randomly selected and are indispensable. The present application is based on the high complementarity of the two in electronic structure, catalytic function and synergistic mechanism, which cannot be simply replaced by other metal combinations. The multi-level pores (large pores-mesopores-micropores) created by zinc evaporation form a "highway network", with large pores as the main channel, mesopores and micropores transporting reactants to the deepest active sites. In addition, the Ni and Zn atoms are in close contact at the atomic level, and the electrons partially transfer from Zn to Ni, fine-tuning the d-electron orbital structure of Ni, optimizing its dissociation adsorption energy for H2 molecules and the adsorption strength of reactant molecules (such as C-Cl bond), making it more prone to hydrogenation / breaking bond reactions. Other metals (such as Co, Fe, Cu) cannot simultaneously achieve the dual functions of "pore creation" and "electronic assistant". They are competitive or interfering, while Zn is synergistic and complementary. Comparative Example 1 and Comparative Example 2 lack Zn and Ni, so they cannot obtain such a developed porous structure and optimized electronic environment, and their corresponding CEC conversion rate, VC selectivity and yield are greatly affected. Comparative Example 3 changes the ratio of nickel source to zinc source, which is slightly better than Comparative Examples 1-2, but still has a large gap with the example, indicating that the ratio of nickel source to zinc source is not randomly selected. Comparative Example 4 does not use a surfactant, so that the catalyst cannot form a corresponding two-dimensional nanosheet structure, resulting in the failure of the catalyst.

[0162] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each example can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A catalyst for vinylene carbonate synthesis, characterized by, The nickel-zinc bimetal nanosheet is compounded with boron-doped carbon material; the catalyst is prepared by using a nickel source, a zinc source, a carbon source, a surfactant and a boron source as raw materials through hydrothermal reaction, calcination and reduction steps; The carbon source is one or more of glucose, sucrose and citric acid, and the surfactant is one or more of sodium dodecyl sulfate, sodium diisooctyl sulfosuccinate, cetyltrimethylammonium bromide and polyvinylpyrrolidone; The molar ratio of the carbon source to the boron source is 2-5:1; The nickel source is nickel nitrate hexahydrate, the zinc source is zinc nitrate hexahydrate, and the amount of the surfactant is 10%-50% of the total mass of the nickel nitrate hexahydrate and the zinc nitrate hexahydrate; The molar ratio of the nickel nitrate hexahydrate to the zinc nitrate hexahydrate is 1-3:

1.

2. The catalyst for vinylene carbonate synthesis according to claim 1, characterized by, The boron source is boric acid.

3. The method for producing a catalyst for vinylene carbonate synthesis according to any one of claims 1 to 2, characterized by, The catalyst for vinylidene carbonate synthesis is prepared according to the following steps: S1, precursor synthesis: dissolve nickel nitrate hexahydrate and zinc nitrate hexahydrate in deionized water, denoted as solution A, dissolve the carbon source, the boron source and the surfactant in deionized water, denoted as solution B, drop solution A into solution B and stir, keep at 150-180℃ for 8-12 hours, after cooling, centrifuge and wash the precipitate and dry to obtain a precursor; S2, calcination: the precursor obtained in step S1 is calcined at a temperature increasing rate of 1-3℃ / min to 450-550℃ for 2-3 hours; S3, reduction: after the product of step S2 is cooled to room temperature, H2 / Ar is introduced for reduction for 1.5-3 hours, and then cooled to room temperature.

4. Use of the catalyst for vinylene carbonate synthesis according to any one of claims 1 to 2, characterized in that, The catalyst for vinylidene carbonate synthesis is used as a catalyst for the catalytic dehydrochlorination reaction of chloroethylene carbonate to generate vinylidene carbonate.

5. Use of a catalyst for vinylene carbonate synthesis according to claim 4, characterized in that, The steps of the catalytic dehydrochlorination reaction of chloroethylene carbonate to generate vinylidene carbonate are as follows: (1) catalyst filling: the catalyst for vinylidene carbonate synthesis is loaded into a fixed bed reactor to form a catalyst bed in the fixed bed reactor; (2) catalytic reaction: chloroethylene carbonate is introduced into the fixed bed reactor, and the chloroethylene carbonate enters the catalyst bed, the catalytic reaction temperature is 200-400℃, the hydrogen chloride in the chloroethylene carbonate is removed, and the crude vinylidene carbonate is collected, and the tail gas is absorbed by water and lye; (3) crude product distillation: the crude vinylidene carbonate obtained in step (2) is distilled at an oil temperature of 55-75℃ and a vacuum degree of 300-500 Pa to obtain a distillation product; (4) rectification: collect and mix multiple batches of the distillation product obtained in step (3) to obtain a rectification product.

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