Application of a boron nitride non-metallic catalyst in acetylene hydrochlorination

Abstract

The invention discloses a kind of application of boron nitride nonmetallic catalyst in acetylene hydrochlorination, the preparation method of the boron nitride nonmetallic catalyst is as follows: 1) boron-containing compound, nitrogen-containing compound and halide are added to deionized water, fully dissolved to obtain a mixed solution;Secondly, template agent KIT 6 is added to the mixed solution and stirred;Then it is transferred to a hydrothermal reactor with a polytetrafluoroethylene liner, sealed after the air in the reactor is purged with nitrogen and reacted at 250 400 DEG C for 20 40h;2) after the reaction is completed, the product is washed with deionized water suction filtration, transferred to HF solution and soaked to remove residual template agent, then washed with deionized water to neutrality, and dried to obtain a boron nitride nonmetallic catalyst. In the present invention, the catalyst preparation method is simple and has high activity and high stability at relatively low reaction temperatures.

Description

Technical Field

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

[0002] Polyvinyl chloride (PVC), one of the most commonly used plastics worldwide, is used in all aspects of daily life. PVC is produced by the polymerization of vinyl chloride monomer (VCM). Currently, the primary method for producing VCM in my country is the acetylene process, using an activated carbon-supported mercury catalyst. However, the volatilization and toxicity of mercury during the production process pose a serious threat to humans and the environment. This has compelled the search for a new mercury-free catalyst to replace the existing one.

[0003] Mercury-free catalysts are categorized into metal catalysts and non-metal catalysts. Huctings et al. predict that Au-based catalysts are the most promising alternatives to Hg-based catalysts, but the cost of Au limits their widespread adoption. In recent years, numerous studies have demonstrated the potential of non-metal catalysts as catalysts for acetylene hydrochlorination. For example, the nitrogen-doped carbon materials derived from ZIFs reported by Zhang Jinli et al. and the hydrothermally synthesized NPC materials reported by Dai Bin et al. have all demonstrated promising activity. However, the preparation of these catalysts is cumbersome, and their activity and stability do not yet meet industrial requirements.

[0004] CN108187712 A discloses a non-metallic catalyst, its preparation method, and its application in the preparation of vinyl chloride by acetylene hydrochlorination, as well as a catalyst regeneration method. The catalyst is a structurally stable porous boron nitride, mainly composed of boron and nitrogen elements in 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 boundaries. The patent introduces defect sites and heteroatom doping to enable boron nitride itself to have the ability to catalyze acetylene hydrochlorination. By utilizing the high thermal conductivity of boron nitride itself, the reaction can be carried out stably at higher temperatures (200-300°C), with high reactivity and good vinyl chloride selectivity. However, the optimal reaction temperature for the acetylene hydrochlorination reaction under the action of this catalyst is 280°C. When the reaction temperature is reduced to 220°C, the reaction is carried out under the conditions of an acetylene space velocity of 2.4ml / min"gcat and hydrogen chloride:acetylene = 1:1, the reaction conversion rate is only 75%. According to the paper subsequently published by the inventors 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 the bulk. h-BN does not show any detectable activity, so the catalytic activity of porous boron nitride may be due to the abundant defects and edge sites. The paper shows that its optimal catalyst is at 200℃ and 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 a Controllable Synthesis Method for Cubic Boron Nitride under Mild Conditions. PhD Dissertation, Shandong University, 2010] disclosed a conventional hydrothermal synthesis method for cubic boron nitride (cBN). The method involves dissolving 0.1 mol H₃BO₃, 0.3 mol NaN₃, 10 ml N₂H₄·H₂O, and 0.15 mol NaCl / 0.05 mol NaF in 500 ml of deionized water. After complete dissolution, the mixture is transferred to a reactor. After purging with high-purity nitrogen, the reactor is sealed and heated to 300°C at a rate of 0.5°C / min and held at this temperature for 20 hours. The mixture is then cooled to room temperature at the same rate. Pure cBN microcrystals are obtained after washing, filtration, and drying. However, there are currently no reports on the application of cBN in the preparation of vinyl chloride by the acetylene hydrochlorination process. Summary of the Invention

[0007] The present invention aims to provide a boron nitride non-metallic catalyst for use in acetylene hydrochlorination. 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-metallic catalyst is used in the hydrochlorination reaction of acetylene. The preparation method of the boron nitride non-metallic 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; then, 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; and 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 template, and 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 soaking 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 the 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 a further preference, 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 innovations and advantages of the present invention are:

[0024] 1. The preparation method of the boron nitride non-metallic catalyst of the present invention introduces a template agent KIT-6 on the basis of the conventional hydrothermal synthesis method of cubic boron nitride (c-BN), thereby obtaining cubic boron nitride with a pore structure. The obtained boron nitride non-metallic catalyst is applied to the acetylene hydrochlorination reaction and can have 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 using specific embodiments, which 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 may make adjustments based on the above invention.

[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 and dissolve thoroughly in 200ml of deionized water to obtain a mixed solution. Add 2g of KIT-6 template to the mixed solution and stir thoroughly. Then transfer the mixture to a hydrothermal reactor and react at 250°C for 20h.

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

[0030] 3) 5 ml of the BN non-metallic catalyst prepared in step 2) was placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, and 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. Initially, the acetylene conversion was 94.63% and the vinyl chloride selectivity was 97.58%. After 1000 hours of reaction, the acetylene conversion 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 and dissolve thoroughly in 200ml of deionized water to obtain a mixed solution. Add 2g of KIT-6 template to the mixed solution and stir thoroughly. Then transfer the mixture to a hydrothermal reactor and react at 300°C for 24h.

[0033] 2) The solid product obtained in step 1) was filtered and washed with deionized water, and then transferred to 10 wt% HF and soaked for 1 hour to remove the residual template. It was 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 placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, and 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. Initially, the acetylene conversion was 99.42% and the vinyl chloride selectivity was 99.07%. After 1000 hours of reaction, the acetylene conversion 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 and dissolve thoroughly in 300ml of deionized water to obtain a mixed solution. Add 2g of KIT-6 template to the mixed solution and stir thoroughly. Then transfer the mixture to a hydrothermal reactor and react at 350°C for 20h.

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

[0038] 3) 5 ml of the BN non-metallic catalyst prepared in step 2) was placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, and 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. Initially, the acetylene conversion was 97.37% and the vinyl chloride selectivity was 98.84%. After 1000 hours of reaction, the acetylene conversion 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 and dissolve thoroughly in 200ml of deionized water to obtain a mixed solution. Add 2g of KIT-6 template to the mixed solution and stir thoroughly. Then transfer the mixture to a hydrothermal reactor and react at 300°C for 24h.

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

[0042] 3) 5 ml of the BN non-metallic catalyst prepared in step 2) was placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, and 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. Initially, the acetylene conversion was 97.13% and the vinyl chloride selectivity was 99.53%. After 1000 hours of reaction, the acetylene conversion 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 and dissolve thoroughly in 200ml of deionized water to obtain a mixed solution. Add 2g of KIT-6 template to the mixed solution and stir thoroughly. Then transfer the mixture to a hydrothermal reactor and react at 350°C for 24h.

[0045] 2) The solid product obtained in step 1) was filtered and washed with deionized water, and then transferred to 10 wt% HF and soaked for 1 hour to remove the residual template. It was 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 placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, and 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. Initially, the acetylene conversion was 96.79% and the vinyl chloride selectivity was 98.73%. After 1000 hours of reaction, the acetylene conversion 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, add them to 200ml of deionized water, and dissolve thoroughly to obtain a mixed solution. Stir thoroughly. Then transfer the solution to a hydrothermal reactor and react at 300°C for 24h.

[0049] 2) The solid product obtained in step 1) was filtered and washed with deionized water until 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 placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 200°C, and 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. Initially, the acetylene conversion was 12.08% and the vinyl chloride selectivity was 63.29%. After 1000 hours of reaction, the acetylene conversion 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 methyldiphenylphosphine oxide (MDPO) separately, dissolve thoroughly in 20ml of ethanol, add 6.2g of activated carbon (AC), and stir evenly. Immerse for 8-10 hours, and dry at 100°C for 12 hours to obtain a copper-supported metal catalyst.

[0054] 2) 5 ml of the Cu catalyst prepared in step 1) was placed in a fixed bed reactor, nitrogen was introduced and the temperature was raised to 180°C, and 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 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. Initially, the acetylene conversion was 99.13% and the vinyl chloride selectivity was 99.21%. After 1000 hours of reaction, the acetylene conversion was 95.54% and the vinyl chloride selectivity was 98.82%.

[0055] As can be seen from Comparative Example 2, cubic boron nitride has an effect comparable to that of a supported metal catalyst in the acetylene hydrochlorination reaction.

Claims

1. Application of a boron nitride non-metallic catalyst in acetylene hydrochlorination, 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; then, 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 300° 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; and the molar ratio of the boron-containing compound, the nitrogen-containing compound, and the halide is 2:6-12:0.8-4; 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 template, and 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 2:8-11:1-3.

5.

4. The use according to claim 1, wherein: 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.

5. 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.

6. 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 300°C, and reaction time of 20-30h.

7. 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.

8. The use according to any one of claims 1 to 7, characterized in that: The application is specifically as follows: the boron nitride catalyst is loaded into a fixed bed reactor, and the 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.

9. The use according to claim 8, 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 .