Application of boron nitride nonmetal catalyst in acetylene hydrochlorination reaction

Abstract

The invention discloses an application of a boron nitride non-metal catalyst in acetylene hydrochlorination reaction, and a preparation method of the boron nitride non-metal catalyst comprises the following steps: 1) adding a boron-containing compound, a nitrogen-containing compound and a halide into deionized water, and fully dissolving to obtain a mixed solution; secondly, adding a template agent KIT-6 into the mixed solution, and uniformly stirring; transferring into a hydrothermal reaction kettle with a polytetrafluoroethylene lining, purging air in the reaction kettle with nitrogen, sealing, and reacting at 250-400 DEG C for 20-40 hours; and 2) after the reaction is finished, carrying out suction filtration and washing on a product with deionized water, transferring the product into an HF solution to be soaked so as to remove the residual template agent, then washing the product with deionized water until the product is neutral, and drying the product to obtain the boron nitride non-metal catalyst. The preparation method of the catalyst is simple, and the catalyst has high activity and high stability at a low reaction temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to application of a boron nitride non-metal catalyst in catalyzing acetylene hydrochlorination reaction. Background Art

[0002] Polyvinyl chloride (PVC) is one of the most commonly used plastics in the world and is used in all aspects of daily life. PVC is obtained by the polymerization reaction of vinyl chloride monomer (VCM). At present, the main method for producing VCM in my country is the acetylene method, and the catalyst system used is a mercury catalyst supported by activated carbon. However, the volatilization and toxicity of mercury in the production process pose a serious threat to humans and the environment. This forces us to find a new mercury-free catalyst to replace the existing catalyst.

[0003] Mercury-free catalysts are divided into metal catalysts and non-metal catalysts, among which Huctings et al. predicted that Au-based catalysts are most likely to replace Hg-based catalysts, but the cost of Au limits the promotion of this catalyst. In recent years, a large number of studies have shown that non-metal catalysts have the potential to be used as catalysts for acetylene hydrochlorination. For example, the nitrogen-doped carbon materials derived from ZIF reported by Zhang Jinli et al. and the hydrothermal synthesized NPC materials reported by Dai Bin et al. All of them show good activity. However, the preparation of the above catalysts is cumbersome, and the activity and stability do not meet industrial requirements.

[0004] CN108187712 A discloses a non-metallic catalyst and its preparation method and application in the preparation of vinyl chloride by acetylene hydrochlorination, as well as a catalyst regeneration method. The catalyst is a porous boron nitride with a stable structure, mainly composed of boron and nitrogen elements with an atomic ratio of about 1:1-1:1.5, doped with a small amount of carbon, oxygen, and hydrogen elements, and does not contain metal. The porous boron nitride is a defect-rich boron nitride, which means that nitrogen and / or boron are missing on the layered surface and boundary. The patent introduces defect sites and heteroatom doping to make the boron nitride itself have the ability to catalyze the acetylene hydrochlorination reaction, and utilizes the high thermal conductivity of boron nitride itself to make the reaction stable at a higher temperature (200-300°C), and has high reactivity and good vinyl chloride selectivity. However, the optimal reaction temperature of the acetylene hydrochlorination reaction under the action of the catalyst is 280°C. When the reaction temperature is reduced to 220°C, the reaction is carried out under the conditions of acetylene space velocity 2.4ml / min〃gcat and hydrogen chloride: acetylene = 1:1, and the reaction conversion rate is only 75%. According to the paper subsequently published by the inventor of the patent [Pan Li, Haobo Li, Xiulian Pan, Kai Tie, Tingting Cui, Minzheng Ding, Xinhe Bao.

[0005] Catalytically Active Boron Nitride in Acetylene Hydrochlorination.ACSCatal.2017,7,8572-8577], compared with the composition and structure of h-BN, detailed characterization of porous boron nitride shows that both catalysts have the same BN structure in bulk. h-BN does not show any detectable activity, so the catalytic activity of porous boron nitride may originate from the abundant defects and edge sites. The paper shows that its best catalyst is at 200℃, GHSV = 1.2mLmin -1 g -1 (equivalent to 40h -1 ), HCl / acetylene = 1 / 1, the selectivity of vinyl chloride exceeds 96%, but the conversion rate of ethylene is only 72%.

[0006] Lian Gang [Lian Gang. Exploration of controllable synthesis method of cubic boron nitride under mild conditions. Doctoral dissertation of Shandong University, 2010] disclosed a method for synthesizing cubic boron nitride (cBN) by conventional hydrothermal synthesis method, which is: directly dissolve 0.1mol H3BO3, 0.3mol NaN3, 10ml N2H4·H2O and 0.15mol NaCl / 0.05mol NaF in 500ml deionized water, transfer them into a reactor after they are fully dissolved, seal the reactor after purging with high-purity nitrogen, heat to 300℃ at a rate of 0.5℃ / min and keep the temperature constant for 20h, then cool to room temperature at the same rate, wash, filter and dry to obtain pure cBN microcrystalline samples. However, there is no report on the application of cBN in the preparation of vinyl chloride by acetylene hydrochlorination. Summary of the invention

[0007] The invention aims to provide a boron nitride non-metal catalyst for use in acetylene hydrochlorination reaction. The catalyst has a simple preparation method and has high activity and high stability at a relatively low reaction temperature.

[0008] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:

[0009] A boron nitride non-metal catalyst is used in the acetylene hydrochlorination reaction. The preparation method of the boron nitride non-metal catalyst is as follows:

[0010] 1) Adding a boron-containing compound, a nitrogen-containing compound and a halide to deionized water and fully dissolving them to obtain a mixed solution; secondly, adding a template agent KIT-6 to the mixed solution and stirring it evenly; then transferring it to a hydrothermal reactor lined with polytetrafluoroethylene, purging the air in the reactor with nitrogen, sealing it and reacting it at 250-400° C. for 20-40 hours; the boron-containing compound is selected from at least one of boric acid, boron trioxide, boron halide and fluoroboric acid; the nitrogen-containing compound is selected from at least one of sodium azide, melamine, guanidine hydrochloride, urea, aniline and hydrazine hydrate; the halide is selected from at least one of sodium fluoride, potassium fluoride, sodium chloride and potassium chloride;

[0011] 2) After the reaction is completed, the product is filtered and washed with deionized water, transferred to an HF solution for immersion to remove residual templates, then washed with deionized water until neutral, and dried to obtain a boron nitride non-metallic catalyst.

[0012] Preferably, in step 1), the nitrogen-containing compound is selected from a combination of hydrazine hydrate and sodium azide in a molar ratio of 1-2:2.

[0013] Preferably, in step 1), the molar ratio of the boron-containing compound, the nitrogen-containing compound and the halide is 2:6-12:0.8-4, more preferably 2:8-11:1-3.5.

[0014] Preferably, in step 1), in the mixed solution, the mass volume ratio of the boron-containing compound to deionized water is 0.8-2.5 g / 100 mL.

[0015] Preferably, in step 1), the mass ratio of the template KIT-6 to the boron-containing compound is 1:0.5-2.5.

[0016] Preferably, in step 1), the hydrothermal reaction conditions are: heating rate of 3-8°C / min, more preferably 5°C / min; reaction temperature of 280-320°C, more preferably 300°C; reaction time of 20-30h, more preferably 24h.

[0017] Preferably, in step 2), the concentration of the HF solution is 10-20 wt%, more preferably 10%; and the immersion time is 0.5-1.5 h, more preferably 1 h.

[0018] Preferably, in step 2), the drying conditions are: drying at 80-100° C. for 8-12 h.

[0019] Preferably, the application is specifically as follows: in a fixed bed reactor, the boron nitride catalyst is loaded, and reaction gases HCl and C2H2 are introduced for reaction, wherein the molar ratio of the reaction gases is n(HCl):n(C2H2)=1:1-1.2:1, the reaction temperature is 140-230°C, and the acetylene volume space velocity is 30-200h -1 , the reaction produces vinyl chloride.

[0020] As further preferred, the reaction temperature is 200°C.

[0021] As a further preference, the molar ratio of the reaction gas substances is n(HCl):n(C2H2)=1.1:1.

[0022] As a further preference, the acetylene volume space velocity is 30h -1 .

[0023] Compared with the prior art, the innovation and advantages of the present invention are:

[0024] 1. The preparation method of the boron nitride non-metal catalyst of the present invention introduces a template agent KIT-6 on the basis of a method for synthesizing cubic boron nitride (c-BN) by a conventional hydrothermal synthesis method, thereby obtaining cubic boron nitride with a pore structure. The obtained boron nitride non-metal catalyst is applied to acetylene hydrochlorination reaction and has high catalytic activity and good stability at a relatively low reaction temperature;

[0025] 2. The present invention prepares boron nitride by a traditional hydrothermal method, which has a simple method, mild conditions, safe operation and low production cost. DETAILED DESCRIPTION

[0026] The present invention is described below with specific embodiments, but they should not be construed as limiting the scope of protection of the present invention, and are only used to further illustrate the present invention. Those skilled in the art can make adjustments based on the above invention content.

[0027] Example 1

[0028] 1) Weigh 2.472g of boric acid, 7.801g of sodium azide, 3.508g of sodium chloride and 3ml of hydrazine hydrate respectively, add 200ml of deionized water to fully dissolve, and then add 2g of KIT-6 template to the mixed solution, stir evenly, and then transfer to a hydrothermal reactor and react at 250℃ for 20h.

[0029] 2) The solid product obtained in step 1) is filtered and washed with deionized water, and transferred to 10wt% HF to be immersed for 0.5h to remove the residual template, and then washed with deionized water until neutral, and dried at 90°C for 10h to obtain a cubic boron nitride non-metallic catalyst.

[0030] 3) 5 ml of the BN non-metallic catalyst prepared in step 2) was taken and placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, then hydrogen chloride was introduced for activation for 1 hour, and then a mixture of hydrogen chloride and acetylene was introduced at a temperature of 200°C and an acetylene space velocity of 30 h -1 The reaction was carried out under the conditions of n(HCl):n(C2H2)=1.1:1. At the initial stage of the reaction, the acetylene conversion rate was 94.63% and the vinyl chloride selectivity was 97.58%; after 1000 hours of reaction, the acetylene conversion rate was 89.94% and the vinyl chloride selectivity was 98.15%.

[0031] Example 2

[0032] 1) Weigh 2.472g of boric acid, 7.801g of sodium azide, 3.508g of sodium chloride and 4ml of hydrazine hydrate respectively, add 200ml of deionized water to fully dissolve, and then add 2g of KIT-6 template to the mixed solution, stir evenly, and then transfer to a hydrothermal reactor and react at 300℃ for 24h.

[0033] 2) The solid product obtained in step 1) is filtered and washed with deionized water, and transferred to 10wt% HF to be immersed for 1 hour to remove the residual template, and then washed with deionized water until neutral, and dried at 90°C for 10 hours to obtain a cubic boron nitride non-metallic catalyst.

[0034] 3) 5 ml of the BN non-metallic catalyst prepared in step 2) was taken and placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, then hydrogen chloride was introduced for activation for 1 hour, and then a mixture of hydrogen chloride and acetylene was introduced at a temperature of 200°C and an acetylene space velocity of 30 h -1 The reaction was carried out under the conditions of n(HCl):n(C2H2)=1.1:1. At the initial stage of the reaction, the acetylene conversion rate was 99.42% and the vinyl chloride selectivity was 99.07%; after 1000 hours of reaction, the acetylene conversion rate was 96.33% and the vinyl chloride selectivity was 98.81%.

[0035] Example 3

[0036] 1) Weigh 2.966g of boric acid, 9.361g of sodium azide, 4.210g of sodium chloride and 4ml of hydrazine hydrate respectively, add 300ml of deionized water to fully dissolve, and then add 2g of KIT-6 template to the mixed solution, stir evenly, and then transfer to a hydrothermal reactor and react at 350℃ for 20h.

[0037] 2) The solid product obtained in step 1) is filtered and washed with deionized water, and transferred to 10wt% HF to be immersed for 0.5h to remove the residual template, and then washed with deionized water until neutral, and dried at 90°C for 10h to obtain a cubic boron nitride non-metallic catalyst.

[0038] 3) 5 ml of the BN non-metallic catalyst prepared in step 2) was taken and placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, then hydrogen chloride was introduced for activation for 1 hour, and then a mixture of hydrogen chloride and acetylene was introduced at a temperature of 200°C and an acetylene space velocity of 30 h -1 The reaction was carried out under the conditions of n(HCl):n(C2H2)=1.1:1. At the initial stage of the reaction, the acetylene conversion rate was 97.37% and the vinyl chloride selectivity was 98.84%; after 1000 hours of reaction, the acetylene conversion rate was 94.29% and the vinyl chloride selectivity was 98.77%.

[0039] Example 4

[0040] 1) Weigh 2.318g of boric acid, 6.261g of sodium azide, 1.052g of sodium fluoride and 4ml of hydrazine hydrate respectively, add 200ml of deionized water to fully dissolve, and then add 2g of KIT-6 template to the mixed solution, stir evenly, and then transfer to a hydrothermal reactor and react at 300℃ for 24h.

[0041] 2) The solid product obtained in step 1) is filtered and washed with deionized water, and transferred to 10wt% HF to be immersed for 0.5h to remove the residual template, and then washed with deionized water until neutral, and dried at 90°C for 10h to obtain a cubic boron nitride non-metallic catalyst.

[0042] 3) 5 ml of the BN non-metallic catalyst prepared in step 2) was taken and placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, then hydrogen chloride was introduced for activation for 1 hour, and then a mixture of hydrogen chloride and acetylene was introduced at a temperature of 200°C and an acetylene space velocity of 30 h -1 The reaction was carried out under the conditions of n(HCl):n(C2H2)=1.1:1. At the initial stage of the reaction, the acetylene conversion rate was 97.13% and the vinyl chloride selectivity was 99.53%; after 1000 hours of reaction, the acetylene conversion rate was 94.16% and the vinyl chloride selectivity was 99.28%.

[0043] Example 5

[0044] 1) Weigh 3.814g of boric acid, 6.741g of sodium azide, 1.217g of sodium fluoride and 4ml of hydrazine hydrate respectively, add 200ml of deionized water to fully dissolve, and then add 2g of KIT-6 template to the mixed solution, stir evenly, and then transfer to a hydrothermal reactor and react at 350℃ for 24h.

[0045] 2) The solid product obtained in step 1) is filtered and washed with deionized water, and transferred to 10wt% HF to be immersed for 1 hour to remove the residual template, and then washed with deionized water until neutral, and dried at 90°C for 10 hours to obtain a cubic boron nitride non-metallic catalyst.

[0046] 3) 5 ml of the BN non-metallic catalyst prepared in step 2) was taken and placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, then hydrogen chloride was introduced for activation for 1 hour, and then a mixture of hydrogen chloride and acetylene was introduced at a temperature of 200°C and an acetylene space velocity of 30 h -1 The reaction was carried out under the conditions of n(HCl):n(C2H2)=1.1:1. At the initial stage of the reaction, the acetylene conversion rate was 96.79% and the vinyl chloride selectivity was 98.73%; after 1000 hours of reaction, the acetylene conversion rate was 93.04% and the vinyl chloride selectivity was 99.18%.

[0047] Comparative Example 1

[0048] 1) Weigh 2.472g of boric acid, 7.801g of sodium azide and 4ml of hydrazine hydrate respectively, add 200ml of deionized water to fully dissolve, and stir to obtain a mixed solution. Then transfer to a hydrothermal reactor and react at 300℃ for 24h.

[0049] 2) The solid product obtained in step 1) is filtered and washed with deionized water until it becomes neutral, and dried at 90° C. for 10 h to obtain a hexagonal boron nitride non-metallic catalyst.

[0050] 3) 5 ml of the BN non-metallic catalyst prepared in step 2) was taken and placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, then hydrogen chloride was introduced for activation for 1 hour, and then a mixture of hydrogen chloride and acetylene was introduced at a temperature of 200°C and an acetylene space velocity of 30 h -1 The reaction was carried out under the conditions of n(HCl):n(C2H2)=1.1:1. At the initial stage of the reaction, the acetylene conversion rate was 12.08% and the vinyl chloride selectivity was 63.29%; after 1000 hours of reaction, the acetylene conversion rate was 3.04% and the vinyl chloride selectivity was 53.06%.

[0051] It can be seen from Comparative Example 1 that hexagonal boron nitride has almost no catalytic effect on the acetylene hydrochlorination reaction.

[0052] Comparative Example 2

[0053] 1) Weigh 3.15g of copper chloride and 0.63g of methyl diphenylphosphine oxide (MDPO) respectively, add 20ml of ethanol to fully dissolve, add 6.2g of activated carbon (AC), stir evenly, soak for 8-10h, and dry at 100℃ for 12h to obtain a copper-supported metal catalyst.

[0054] 2) 5 ml of the Cu catalyst prepared in step 1) was loaded into a fixed bed reactor, nitrogen was introduced and the temperature was raised to 180°C, then hydrogen chloride was introduced for activation for 1 h, and then a mixture of hydrogen chloride and acetylene was introduced at a temperature of 1800°C and an acetylene space velocity of 30 h -1The reaction was carried out under the conditions of n(HCl):n(C2H2)=1.1:1. At the initial stage of the reaction, the acetylene conversion rate was 99.13% and the vinyl chloride selectivity was 99.21%; after 1000 hours of reaction, the acetylene conversion rate was 95.54% and the vinyl chloride selectivity was 98.82%.

[0055] It can be seen from Comparative Example 2 that cubic boron nitride has an effect comparable to that of a supported metal catalyst on acetylene hydrochlorination.

Claims

1. Application of a boron nitride non-metallic catalyst in acetylene hydrochlorination reaction, characterized in that: The preparation method of the boron nitride non-metallic catalyst is as follows: 1) Adding a boron-containing compound, a nitrogen-containing compound and a halide to deionized water and fully dissolving them to obtain a mixed solution; secondly, adding a template agent KIT-6 to the mixed solution and stirring it evenly; then transferring it to a hydrothermal reactor lined with polytetrafluoroethylene, purging the air in the reactor with nitrogen, sealing it and reacting it at 250-400° C. for 20-40 hours; the boron-containing compound is selected from at least one of boric acid, boron trioxide, boron halide and fluoroboric acid; the nitrogen-containing compound is selected from at least one of sodium azide, melamine, guanidine hydrochloride, urea, aniline and hydrazine hydrate; the halide is selected from at least one of sodium fluoride, potassium fluoride, sodium chloride and potassium chloride; 2) After the reaction is completed, the product is filtered and washed with deionized water, transferred to an HF solution for immersion to remove residual templates, then washed with deionized water until neutral, and dried to obtain a boron nitride non-metallic catalyst.

2. The use according to claim 1, characterized in that: In step 1), the nitrogen-containing compound is selected from a combination of hydrazine hydrate and sodium azide in a molar ratio of 1-2:

2.

3. The use according to claim 1, characterized in that: In step 1), the molar ratio of the boron-containing compound, the nitrogen-containing compound and the halide is 2:6-12:0.8-4.

4. The use according to claim 3, characterized in that: In step 1), the molar ratio of the boron-containing compound, the nitrogen-containing compound and the halide is 2:8-11:1-3.

5.

5. The use according to claim 1, characterized in that: In step 1), in the mixed solution, the mass volume ratio of the boron-containing compound to deionized water is 0.8-2.5 g / 100 mL.

6. The use according to claim 1, characterized in that: In step 1), the mass ratio of the template KIT-6 to the boron-containing compound is 1:0.5-2.

5.

7. The use according to claim 1, characterized in that: In step 1), the hydrothermal reaction conditions are: heating rate of 3-8°C / min, reaction temperature of 280-320°C, and reaction time of 20-30h.

8. The use according to claim 1, characterized in that: In step 2), the concentration of the HF solution is 10-20 wt %, and the soaking time is 0.5-1 h.

9. The use according to any one of claims 1 to 8, characterized in that: The application is specifically as follows: in a fixed bed reactor, the boron nitride catalyst is loaded, and reaction gases HCl and C2H2 are introduced for reaction, wherein the molar ratio of the reaction gases is n(HCl):n(C2H2)=1:1-1.2:1, the reaction temperature is 140-230°C, and the acetylene volume space velocity is 30-200h -1 , the reaction produces vinyl chloride.

10. The use according to claim 9, characterized in that: The reaction temperature is 200°C, the molar ratio of the reaction gas is n(HCl):n(C2H2)=1.1:1, and the acetylene volume space velocity is 30h -1 .