A method for preparing a high specific surface area carbonitride material catalyst using carbon dioxide and its application in acetylene hydrochlorination

Abstract

The present invention belongs to the technical field of the preparation of carbonitrogen materials, and particularly relates to a method for preparing a catalyst for high specific surface area carbonitrogen materials by using carbon dioxide and its application in acetylene hydrochlorination. A metal-supported molecular sieve catalyst is used as a template; in a gas-solid phase reactor, a carbon source and a nitrogen source are fed in a mixed manner for deposition treatment, and then the template is removed, washed with water, and dried to obtain a carbonitrogen material; or deposition treatment is carried out through a carbon source in a gas-solid phase reactor, then the template is removed, washed with water, and dried, and finally a nitrogen source is introduced for nitridation treatment to obtain a carbonitrogen material. The catalyst prepared by the present invention has the characteristics of controllable morphology, specific surface area, and nitrogen doping amount, simple composition, realization of high-value utilization of carbon dioxide, etc., and different morphologies of carbonitrogen materials can be designed directionally by selecting different template molecular sieves. Moreover, the catalyst does not contain mercury at all, and pre-activation is not required for the application, and it has high thermal stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of carbonitride materials, and particularly relates to a preparation method of a catalyst for efficiently utilizing carbon dioxide to prepare a high specific surface area carbonitride material and its application in acetylene hydrochlorination. Background Art

[0002] As one of the main greenhouse gases, carbon dioxide has a very important impact on global warming. Therefore, it is urgent to accelerate the development and utilization of carbon dioxide and reduce its impact on the greenhouse effect.

[0003] The traditional high-value utilization of carbon dioxide is mainly through hydrogenation to produce aromatics, reforming with lower alkanes to produce syngas (a mixture of carbon monoxide and hydrogen), and further producing high-value-added products such as lower olefins, aromatics, and oil products via the Fischer-Tropsch reaction or the OX-ZEO technology. However, in addition, through certain technical means, carbon dioxide can be directly carbonized to form carbon black, graphite carbon, ordered mesoporous carbon materials, etc. For different types of carbon, it can be used in traditional industrial fields such as rubber, leather, lubricants, food, and sewage treatment, and can also be further modified to play a big role as a catalyst in the catalytic field.

[0004] In recent years, carbonitride materials have been widely used in the catalytic field. The carbon materials themselves are relatively stable and usually have low activity. By performing functionalization treatments such as local hydroxylation, carboxylation, heteroatom doping, etc., more free electrons can be provided for the conduction band, thereby improving the electrical conductivity of the materials and enhancing the possibility of their further application in the catalytic field. Among them, the main research focus is on nitrogen-doped carbon elements. Research shows that the introduction of nitrogen can change the local electronic environment, thereby changing the adsorption behavior of gas molecules at the active center and reducing the activation energy, etc. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing a catalyst for carbonitride materials with a high specific surface area using carbon dioxide and its application in acetylene hydrochlorination. The prepared carbonitride materials have the characteristics of controllable morphology, specific surface area, nitrogen doping amount, simple composition, and realizing the high-value utilization of carbon dioxide, and their main components are carbon and nitrogen elements.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] On the one hand, the present invention provides a method for preparing a catalyst for carbonitride materials with a high specific surface area using carbon dioxide, and the method includes the following steps:

[0008] (1) Using a metal-loaded molecular sieve catalyst as a template,

[0009] (2) In a gas-solid phase reactor, a carbon source and a nitrogen source are mixed and fed for deposition treatment, and then the template is removed, washed with water, and dried to obtain a carbonitride material.

[0010] Or, deposition treatment is carried out with a carbon source in a gas-solid phase reactor, then the template is removed, washed with water, and dried, and finally a nitrogen source is introduced for nitridation treatment to obtain a carbonitride material.

[0011] In the above technical solution, further, the specific surface area of the metal-loaded molecular sieve is 200 - 2000 m 2 / g; the metal includes one or more of Cr, Fe, Co, Ni, Cu, Mo, W, Ru, Rh, Pd, Ag, Au, Pt, and the loading amount is 0.1 - 20 wt.%.

[0012] In the above technical solution, further, the carbon source includes a mixed gas of lower hydrocarbons and CO2; the lower hydrocarbons include one or more of alkanes, alkenes, and alkynes in C1 - C4, and the volume content of CO2 is 1% - 90%.

[0013] In the above technical solution, further, the nitrogen source includes one or more of urea, dicyandiamide, melamine, aniline, amino acids, amine compounds with the structural formula R1-NH2, and amine compounds with the structural formula R1-NH-R2, where R1 and R2 are at least one of H, and alkane, alkene, and alkyne groups in C1 - C12.

[0014] In the above technical solution, further, the temperature of the deposition treatment is 500 - 900 °C, the pressure is 0.05 - 0.5 MPa, the space velocity is 1000 - 10000 ml / g cat / h, and the deposition treatment time is 2 - 200 h.

[0015] In the above technical solution, further, the method for removing the template is: soaking and treating with an HF solution with a mass concentration of 1% - 20% to remove SiO2 and metal oxides, or first treating with a NaOH / KOH solution with a concentration of 0.1 - 10 M to remove SiO2, and then adding an acid for soaking treatment to remove metal elements.

[0016] In the above technical solution, further, the temperature of the nitridation treatment is 500 - 900 °C, and the time is 2 - 24 h.

[0017] On the other hand, the present invention provides an application of the above carbonitride material catalyst in acetylene hydrochlorination.

[0018] In the above technical solution, further, the hydrogen chloride and acetylene raw material gases after drying and water removal are introduced into a gas-solid phase catalytic reactor loaded with a carbon-nitrogen material catalyst for reaction. The volume ratio of hydrogen chloride to acetylene is 0.6 - 1.4:1, the reaction temperature is 140 - 260 °C, and the reaction space velocity is 10 - 500 h -1 , and the reaction pressure is 0.01 - 0.5 MPa.

[0019] The beneficial effects of the present invention are as follows:

[0020] (1) The carbon-nitrogen material catalyst prepared by the present invention is completely mercury-free, and its application does not require pre-activation. It has high thermal stability and will not be deactivated due to unexpected situations in industrial applications, thus solving the problems of mercury emission pollution of existing industrial low-mercury activated carbon catalysts and catalyst deactivation caused by accidental stoppage of hydrogen chloride gas, etc., and showing good application prospects;

[0021] (2) Through the coupling of carbon dioxide and low-carbon hydrocarbons, the high-value utilization of carbon dioxide can be realized, and high-quality carbon species can be produced;

[0022] (3) Through the templating effect of the molecular sieve material, carbon materials with specific structures are generated directionally, such as ordered mesoporous carbon materials CMK-3, CMK-8, FDU-12, FDU-15, etc., which have good application examples in many fields such as environment, catalysis, and chemical engineering;

[0023] (4) The carbon-nitrogen material prepared by introducing a nitrogen source realizes the regulation of the electronic properties and structural properties of the carbon material, and is a good catalyst or carrier material.

[0024] (5) The carbon-nitrogen material involved in the present invention has extremely wide uses. In this application, only the acetylene hydrochlorination process is used as a probe reaction. In fact, it can be well applied in many reaction processes such as ammonia synthesis, syngas conversion, and methane conversion. Description of the Drawings

[0025] Figure 1 It is the BET result of Example 2. Detailed Embodiments

[0026] The following embodiments are only for explaining the present invention. The protection scope of the present invention should include all the contents of the claims, not limited to this embodiment only.

[0027] The raw materials used in the following examples are all conventional products that can be obtained through commercial purchase. The evaluation of the catalyst was carried out in a continuous online gas-solid phase reactor. A typical evaluation process is to load 1000 mg of the catalyst, react at 100 - 300 °C, and the products are detected by an Agilent gas chromatograph 7890B equipped with an FID detector. The chromatographic column used is Plot Q, which has good separation and detection performance for the gas components involved.

[0028] Example 1

[0029] A 20 wt.% Ni / SBA-15 catalyst was prepared by the traditional impregnation method. The specific process was as follows: 5 g of SBA-15, 4.933 g of nickel nitrate hexahydrate, and 50 ml of deionized water were uniformly mixed, stirred until dry, dried at 120 °C, calcined at 800 °C for 4 h, and reduced with hydrogen at 750 °C for 1 h to obtain the Ni / SBA-15 catalyst.

[0030] Take 5 g of the prepared Ni / SBA-15 catalyst, at 850 °C, introduce a mixture of CO2 and CH4 (50 ml / min : 50 ml / min), at atmospheric pressure, continuously introduce for 100 h, then switch to Ar and cool down to collect the catalyst after the reaction;

[0031] The obtained catalyst was soaked and stirred in a 5 M NaOH solution to remove the template. The treatment conditions were room temperature and the treatment time was 3 h. Finally, the obtained system was centrifuged at a speed of more than 12000 revolutions per minute to ensure that the supernatant was not significantly turbid. Then, 100 mL of 1 M HNO3 was added and soaked for 3 hours, and the supernatant was removed by centrifugation again, washed with water, and the above centrifugation - water washing process was repeated 3 times, and dried at 120 °C to obtain the carbon material.

[0032] The specific surface area of the obtained carbon material was measured to be 717 m 2 / g. The morphology was verified by scanning electron microscopy and was consistent with that of the CMK-3 ordered mesoporous carbon material, with high quality.

[0033] The obtained carbon material was nitrided by introducing ammonia at 800 °C for 6 h. The nitrided sample was pelletized, and 1 g of the pelletized sample was taken for the acetylene hydrochlorination reaction. The reaction conditions were: the volume ratio of hydrogen chloride to acetylene was 1.2:1, atmospheric pressure, temperature 180 °C, volume space velocity 30 h -1 , the initial acetylene conversion rate was 75.1%, the vinyl chloride selectivity was 98.5%, and there was no obvious deactivation after reacting for 100 h.

[0034] Example 2

[0035] The 20 wt.% Ni / SBA-15 catalyst was prepared by the traditional impregnation method. The specific process was as follows: 5 g of SBA-15, 4.933 g of nickel nitrate hexahydrate, and 50 ml of deionized water were homogeneously mixed, stirred until dry, dried at 120 °C, calcined at 800 °C for 4 h, and reduced in hydrogen at 750 °C for 1 h to obtain the required catalyst.

[0036] Take 5 g of the prepared Ni / SBA-15 catalyst. At 850 °C, a mixed gas of CO2, CH4, and NH3 (50 ml / min: 50 ml / min: 50 ml / min) was introduced at atmospheric pressure and continuously introduced for 100 h. Then, it was switched to Ar and cooled to collect the catalyst after the reaction.

[0037] The obtained catalyst was treated in a 5 M NaOH solution under the conditions of room temperature for 3 h. Finally, the obtained system was centrifuged at a speed of more than 12,000 revolutions per minute to ensure that the supernatant was not significantly turbid. Then, 100 mL of 1 M HNO3 was added and soaked for 3 hours, and the supernatant was removed by centrifugation again, followed by washing with water. The above centrifugation-washing process was repeated 3 times, and then dried at 120 °C to obtain the carbon-nitrogen material.

[0038] The specific surface area of the carbon-nitrogen material catalyst was measured to be 521 m 2 / g. The morphology of the catalyst was verified by scanning electron microscopy, which was consistent with that of the CMK-3 ordered mesoporous carbon material and had high quality.

[0039] Figure 1 The BET result of the carbon-nitrogen material prepared in Example 2 was a typical type IV adsorption isotherm, indicating that its microstructure was mainly mesoporous.

[0040] The obtained carbon-nitrogen material was pelletized. Then, 1 g of the pelletized sample was taken for the acetylene hydrochlorination reaction. The reaction conditions were as follows: the volume ratio of hydrogen chloride to acetylene was 1.1:1, atmospheric pressure, temperature 180 °C, and volume space velocity 30 h -1 , the initial acetylene conversion rate was 75.1%, the vinyl chloride selectivity was 98.5%, and there was no obvious deactivation after the reaction for 100 h.

[0041] Example 3

[0042] The 10 wt.% Fe / ZSM-5 catalyst was prepared by the traditional impregnation method. The specific process was as follows: 5 g of SBA-15, 3.875 g of ferric nitrate nonahydrate, and 100 ml of deionized water were homogeneously mixed, stirred until dry, dried at 120 °C, calcined at 800 °C for 4 h, and reduced in hydrogen at 750 °C for 1 h to obtain the required catalyst.

[0043] Take 5 g of the prepared Fe / ZSM-5 catalyst, and introduce a mixed gas of CO2 and C2H6 (50 ml / min: 50 ml / min) at 500 °C for 50 h under a pressure of 0.5 Mpa. Then switch to Ar and cool down to collect the catalyst after the reaction. Treat the obtained catalyst in a 5 M NaOH solution at room temperature for 3 h. Finally, centrifuge the resulting system at a speed of more than 12,000 revolutions per minute to ensure that the supernatant is not significantly turbid. Then add 100 mL of 1 M HNO3 and soak for 3 h. Centrifuge again to remove the supernatant, wash with water, repeat the above centrifugation-washing process 3 times, and dry at 120 °C to obtain the required carbon material.

[0044] The specific surface area of the measured carbon material is 727 m 2 / g.

[0045] Nitridize the obtained carbon material at 800 °C for 4 h with acetonitrile as the nitrogen source. Press and granulate the nitrided sample, and take 1 g of the granulated sample for the acetylene hydrochlorination reaction. The reaction conditions are as follows: the volume ratio of hydrogen chloride to acetylene is 1:1, atmospheric pressure, temperature 180 °C, and volume space velocity 30 h -1 , the initial acetylene conversion rate is 78.1%, the vinyl chloride selectivity is 99.5%, and there is no obvious deactivation after 100 h of reaction.

[0046] Example 4

[0047] Prepare a 10 wt.% NiFe / ZSM-5 catalyst by the traditional impregnation method. The specific process is to uniformly mix 5 g of ZSM-5, 2.465 g of nickel nitrate hexahydrate, 3.875 g of iron nitrate hexahydrate, and 100 ml of deionized water, stir until dry, dry at 120 °C, calcine at 800 °C for 4 h, and reduce with hydrogen at 750 °C for 1 h to obtain the required catalyst.

[0048] Take 5 g of the prepared NiFe / ZSM-5 catalyst, and introduce a mixed gas of CO2 and CH4 (50 ml / min: 50 ml / min) at 900 °C for 30 h under a pressure of 1.0 Mpa. Then switch to Ar and cool down to collect the catalyst after the reaction.

[0049] Treat the obtained catalyst in a 5 M NaOH solution at room temperature for 3 h. Finally, centrifuge the resulting system at a speed of more than 12,000 revolutions per minute to ensure that the supernatant is not significantly turbid. Then add 100 mL of 1 M HNO3 and soak for 3 h. Centrifuge again to remove the supernatant, wash with water, repeat the above centrifugation-washing process 3 times, and dry at 120 °C to obtain the required carbon material.

[0050] The obtained carbon material was nitrided by introducing ammonia at 800 °C for 4 h. After nitridation, the sample was pelletized, and 1 g of the pelletized sample was taken for the acetylene hydrochlorination reaction. The reaction conditions were as follows: the volume ratio of hydrogen chloride to acetylene was 1:1, atmospheric pressure, temperature 180 °C, and volume space velocity 30 h -1 , with an initial acetylene conversion rate of 78.1% and a vinyl chloride selectivity of 99.5%, and there was no obvious deactivation after reacting for 100 h.

[0051] Example 5

[0052] A 10 wt.% Mo / ZSM-5 catalyst was prepared by the traditional impregnation method. The specific process was to uniformly mix 5 g of ZSM-5, 0.879 g of ammonium molybdate tetrahydrate, and 100 ml of deionized water, stir until dry, transfer to 120 °C for drying, calcine at 550 °C for 4 h, and carry out methane carbonization treatment at 550 °C for 30 minutes to obtain the required catalyst.

[0053] Take 5 g of the prepared catalyst and introduce a mixture of CO2 and i-C4H 10 (50 ml / min: 50 ml / min) at 500 °C for 10 h continuously, with a pressure of 2 Mpa, and then switch to Ar and cool down to collect the catalyst after the reaction.

[0054] The obtained catalyst was treated in a 20% HF solution under the conditions of room temperature for 3 h. Finally, the obtained system was centrifuged at a speed of more than 12,000 revolutions per minute to ensure that the supernatant was not significantly turbid, then the supernatant was removed, washed with water, and the above centrifugation - water washing process was repeated 3 times, and dried at 120 °C to obtain the required carbon material.

[0055] The specific surface area of the carbon material was measured to be 487 m 2 / g.

[0056] The obtained carbon material was nitrided by introducing ammonia at 800 °C for 4 h. After nitridation, the sample was pelletized, and 1 g of the pelletized sample was taken for the acetylene hydrochlorination reaction. The reaction conditions were as follows: the volume ratio of hydrogen chloride to acetylene was 1.2:1, 2 atmospheres, temperature 180 °C, and volume space velocity 30 h -1 , with an initial acetylene conversion rate of 70.1% and a vinyl chloride selectivity of 99.5%, and there was no obvious deactivation after reacting for 50 h.

[0057] Example 6

[0058] A 0.5 wt.% Pt / ZSM-5 catalyst was prepared by the traditional impregnation method. The specific process was to uniformly mix 5 g of ZSM-5, 0.052 g of anhydrous chloroplatinic acid, and 100 ml of deionized water, stir until dry, transfer to 120 °C for drying, calcine at 550 °C for 4 h, and carry out methane carbonization treatment at 550 °C for 30 minutes to obtain the required catalyst.

[0059] Take 5 g of the prepared Pt / ZSM-5 catalyst, introduce a mixture of CO2 and CH4 (50 ml / min: 50 ml / min) at 900 °C, continuously introduce it for 100 h, then switch to Ar and cool down to collect the catalyst after the reaction.

[0060] Treat the obtained catalyst in 20% HF solution under the conditions of room temperature and 3 h. Finally, centrifuge the obtained system at a speed of more than 12,000 revolutions per minute to ensure that the supernatant is not significantly turbid, then remove the supernatant, wash it with water, repeat the above centrifugation - water washing process 3 times, and dry it at 120 °C to obtain the required carbon material.

[0061] The specific surface area of the measured carbon material is 825 m 2 / g, having a relatively high specific surface area.

[0062] Introduce nitrogen into the obtained carbon material at 800 °C for nitridation treatment for 4 h. After nitridation, the sample is pelletized. Take 1 g of the pelletized sample for acetylene hydrochlorination reaction. The reaction conditions are as follows: the volume ratio of hydrogen chloride to acetylene is 1.05:1, atmospheric pressure, temperature 180 °C, volume space velocity 30 h -1 , the initial acetylene conversion rate is 87.1%, the selectivity of vinyl chloride is 99.5%, and there is no obvious deactivation after 50 h of reaction.

[0063] Example 7

[0064] Prepare 5 wt.% NiMo / MCM-22 catalyst by the traditional impregnation method. The specific process is to uniformly mix 5 g of ZSM-5, 1.233 g of nickel nitrate hexahydrate, 0.513 g of ammonium heptamolybdate hydrate, and 100 ml of deionized water, stir until dry, transfer to 120 °C for drying, calcine at 550 °C for 4 h, and carry out methane carbonization treatment at 550 °C for 30 minutes to obtain the required catalyst.

[0065] Take 5 g of the prepared NiMo / MCM-22 catalyst, introduce a mixture of CO2 and CH4 (50 ml / min: 50 ml / min) at 900 °C, continuously introduce it for 100 h, then switch to Ar and cool down to collect the catalyst after the reaction.

[0066] Treat the obtained catalyst in 20% HF solution under the conditions of room temperature and 3 h. Finally, centrifuge the obtained system at a speed of more than 12,000 revolutions per minute to ensure that the supernatant is not significantly turbid, then remove the supernatant, wash it with water, repeat the above centrifugation - water washing process 3 times, and dry it at 120 °C to obtain the required carbon material.

[0067] The specific surface area of the measured carbon material is 779 m 2 / g, having a relatively high specific surface area.

[0068] The obtained carbon material was nitrided by introducing ammonia at 800 °C for 4 h. After nitridation, the sample was pelletized by tabletting, and 1 g of the pelletized sample was taken for the acetylene hydrochlorination reaction. The reaction conditions were as follows: the volume ratio of hydrogen chloride to acetylene was 1.2:1, the pressure was 0.5 atm, the temperature was 200 °C, and the volume space velocity was 60 h -1 . The initial acetylene conversion was 79.1%, the vinyl chloride selectivity was 99.8%, and there was no obvious deactivation after 20 h of reaction.

Claims

1. A method for preparing a catalyst for high specific surface area carbon nitride materials using carbon dioxide, characterized in that, The method comprises the following steps: (1) Using a metal-loaded molecular sieve catalyst as a template; (2) In a gas-solid phase reactor, mixing and feeding a carbon source and a nitrogen source for deposition treatment, then removing the template, washing with water, and drying to obtain a carbonitride material, or performing deposition treatment with a carbon source in a gas-solid phase reactor, then removing the template, washing with water, and drying, and finally introducing a nitrogen source for nitridation treatment to obtain a carbonitride material; The metal is selected from one or more of Cr, Fe, Co, Ni, Cu, Mo, W, Ru, Rh, Pd, Ag, Au, Pt, and the loading amount is 0.1-20 wt.%; The carbon source is a mixed gas of lower carbon hydrocarbons and CO2, and the lower carbon hydrocarbons are one or more of alkanes, alkenes, and alkynes in C1-C4; The nitrogen source includes one or more of urea, dicyandiamide, melamine, aniline, amino acids, and amine compounds with the structural general formula of R1-NH-R2, where R1 and R2 are at least one of H, alkane, alkene, and alkyne groups in C1-C12; The deposition treatment temperature is 500 - 900 °C, the pressure is 0.05 - 0.5 MPa, the space velocity is 1000 - 10000 ml / g cat / h, and the deposition treatment time is 2 - 200 h.

2. The preparation method according to claim 1, characterized in that, The specific surface area of the metal-loaded molecular sieve is 200 - 2000 m 2 / g.

3. The preparation method according to claim 1, characterized in that, The volume content of CO2 is 1%-90%.

4. The preparation method according to claim 1, characterized in that, The method for removing the template is: soaking and treating with an HF solution with a mass concentration of 1%-20% or first treating with a NaOH / KOH solution with a concentration of 0.1-10M, and then adding an acid for soaking treatment.

5. The preparation method according to claim 1, characterized in that, The temperature of the nitridation treatment is 500-900 °C, and the time is 2-24 h.

6. Application of a carbonitride material catalyst prepared by the preparation method according to any one of claims 1-5 in acetylene hydrochlorination.

7. The application according to claim 6, wherein The dried and dehydrated hydrogen chloride and acetylene raw material gases are introduced into a gas-solid phase catalytic reactor loaded with a carbonitride material catalyst for reaction. The volume ratio of hydrogen chloride to acetylene is 0.6 - 1.4:1, the reaction temperature is 140 - 260 °C, and the reaction space velocity is 10 - 500 h -1 , and the reaction pressure is 0.01 - 0.5 MPa.

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