Highly selective dehydrogenation catalyst and method for making same
By preparing a porous graphite support and loading palladium, the problem of low selectivity and efficiency of existing catalysts in the dehydrogenation of dodecahydro-N-ethylcarbazole was solved, achieving high selectivity and high efficiency in dehydrogenation while reducing costs.
Patent Information
- Application Number
- CN202510292800.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-13
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2045-03-13
AI Technical Summary
Existing catalysts exhibit low selectivity, long catalytic reaction time, and low dehydrogenation rate in the dehydrogenation process of dodecahydro-N-ethylcarbazole, resulting in high costs.
A porous graphite support was prepared by carbonization reaction using 2-methylimidazole and cobalt nitrate as the main materials, and palladium was loaded with dichlorotetraamminepalladium solution and combined with plasma discharge reduction reaction to form a highly selective dehydrogenation catalyst.
It improves catalyst selectivity and dehydrogenation rate, shortens catalytic reaction time, and reduces dehydrogenation cost.
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Figure CN120132834B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of preparation of organic liquid dehydrogenation catalysts, and particularly relates to a high-selectivity dehydrogenation catalyst and a preparation method and application thereof. BACKGROUND
[0002] N-ethylcarbazole is an excellent organic liquid hydrogen storage raw material, which has the advantages of easy hydrogenation and dehydrogenation, low toxicity, good stability, and the like. At present, many research institutes are actively developing organic liquid hydrogen storage materials using N-ethylcarbazole as the main raw material. However, the dodecahydro-N-ethylcarbazole obtained after hydrogenation needs the catalysis of a catalyst to achieve good dehydrogenation effect. A good dehydrogenation catalyst can not only effectively remove hydrogen, but also reduce the dehydrogenation temperature and cost.
[0003] The carrier and the active component are important components of the catalyst. The carrier mainly serves to support and disperse the active component and the additive, plays a role of skeleton support, and can also endow the catalyst with basic physical structure and performance, such as pore structure, specific surface area, macroscopic shape, and mechanical strength. The active component mainly serves to contact the organic liquid and catalyze the dehydrogenation reaction. Within a certain range, the higher the dispersion degree of the active component on the carrier, the more the active sites, and the higher the activity of the catalyst. The carrier of the dehydrogenation catalyst should have a large specific surface area, a concentrated pore size distribution, and a suitable interaction force with the active component. A high-quality catalyst carrier can greatly improve the catalytic effect of the catalyst.
[0004] The patent CN111054382B discloses a catalyst for dehydrogenation reaction of organic liquid hydrogen storage material and a preparation method thereof. The catalyst comprises a platinum-based element or an oxide thereof, wherein the dispersion degree of Pt is not less than 21%. The catalyst comprises the following components in parts by weight: a) 0.1-4.8 parts of a platinum-based element or an oxide thereof, b) 0.1-6.5 parts of an alkali metal or an oxide thereof, c) 0.1-9.6 parts of Ba and / or Sc or an oxide thereof, and d) 80-99 parts of a carrier S selected from Fe-Al-O or Fe-Al-Zr-O composite oxide, thereby realizing dehydrogenation reaction catalysis.
[0005] The above patent realizes dehydrogenation reaction catalysis, but the selectivity for dodecahydro-N-ethylcarbazole is not high, the catalytic reaction time is long, and the dehydrogenation rate is low. Therefore, it is of great significance to develop a catalyst with high selectivity for dodecahydro-N-ethylcarbazole, short catalytic reaction time, and high dehydrogenation rate, which can effectively reduce the cost. SUMMARY
[0006] In view of the deficiencies of the prior art, the present application uses 2-methyl imidazole and cobalt nitrate as main materials, mixes them to obtain a composite metal material, carbonizes the composite metal material to obtain a porous graphite carrier with excellent performance, then dips the porous graphite carrier in a dichlorotetraammine palladium solution to add palladium elements to the porous graphite carrier, and finally loads the palladium elements onto the porous graphite carrier through a discharge reduction reaction to form a dehydrogenation catalyst, thereby solving the technical problems proposed in the background art. Specifically, the technical scheme of the present application includes the following contents:
[0007] A preparation method of a high-selectivity dehydrogenation catalyst, the preparation method comprising the following steps:
[0008] The Pd-porous graphite is obtained by a plasma discharge reduction reaction to obtain the high-selectivity dehydrogenation catalyst.
[0009] Further, the preparation method of the Pd-porous graphite comprises the following steps:
[0010] After the porous graphite carrier is dipped in a dichlorotetraammine palladium solution for 12 h, centrifugal separation is performed, and finally vacuum drying is performed to obtain the Pd-porous graphite;
[0011] The preparation method of the porous graphite carrier comprises the following steps:
[0012] 2-methyl imidazole is added to a methanol solution to stir to obtain a 2-methyl imidazole solution;
[0013] Cobalt nitrate is added to a methanol solution to stir to obtain a cobalt nitrate solution;
[0014] The 2-methyl imidazole solution is added to the cobalt nitrate solution to mix and react, centrifugal separation is performed, washing is performed with a methanol solution, and finally vacuum drying is performed to obtain a composite metal material;
[0015] The composite metal material is heated at a speed of 5 ℃ / min to 600-800 ℃, and carbonized at this temperature for 3 h, and after cooling, the porous graphite carrier is obtained.
[0016] Further, the 2-methyl imidazole solution is obtained by mixing 2-methyl imidazole and a methanol solution according to a weight ratio of 3:200.
[0017] Further, the cobalt nitrate solution is obtained by mixing cobalt nitrate and a methanol solution according to a weight ratio of 1:80.
[0018] Further, the weight ratio of the 2-methyl imidazole solution and the cobalt nitrate solution is 1:1.
[0019] Further, the step of adding the 2-methyl imidazole solution into the cobalt nitrate solution for mixing reaction includes stirring at a rotating speed of 20 r / min for 1 h, and then placing in an environment at 20 DEG C for oxidation for 20-24 h.
[0020] Further, the dichlorotetrammine palladium solution is obtained by mixing dichlorotetrammine palladium and purified water according to a weight ratio of 3:2500.
[0021] Further, the weight ratio of the porous graphite carrier and the dichlorotetrammine palladium solution is 1:16-20.
[0022] Further, the condition of the plasma discharge reduction reaction includes an environment pressure of 60 Pa, a current of 1.2 A, an environment gas of nitrogen, and a reaction time of 1 h.
[0023] A high-selectivity dehydrogenation catalyst prepared by a preparation method of the high-selectivity dehydrogenation catalyst.
[0024] Application of the high-selectivity dehydrogenation catalyst in the field of catalyzing the dehydrogenation of dodecahydro-N-ethylcarbazole, the condition of the application includes adding 0.1 g of the high-selectivity dehydrogenation catalyst to every 10 ml of dodecahydro-N-ethylcarbazole, and then reacting for 6 h at a test temperature of 160 DEG C.
[0025] Compared with the prior art, the present application has the following beneficial effects:
[0026] The present application first takes 2-methyl imidazole and cobalt nitrate as main materials to obtain a basic metal framework, and then obtains special porous graphite through carbonization reaction, and uses the good hardness and heat conduction performance of the porous graphite and the excellent and stable porous structure of the porous graphite as a carrier of the dehydrogenation catalyst. Then, the present application takes a dichlorotetrammine palladium solution as a raw material, and uses the high selectivity of the dichlorotetrammine palladium solution to dodecahydro-N-ethylcarbazole as an active component of the dehydrogenation catalyst. Finally, the present application replaces the conventional chemical discharge reaction with a special discharge reduction reaction to further improve the dispersion and stability of the active component in the carrier, so as to obtain a dehydrogenation catalyst with high selectivity, high catalytic efficiency and high dehydrogenation rate. BRIEF DESCRIPTION OF DRAWINGS
[0027] Figure 1 The testing device of the high-selectivity dehydrogenation catalyst prepared by the present application. DETAILED DESCRIPTION
[0028] The technical solutions of the present application will be clearly and completely described below through embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but 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 fall within the protection scope of the present application.
[0029] Unless otherwise indicated, the starting materials and reagents used in the present application below are commercially available or can be prepared by known methods.
[0030] 2-methylimidazole, cobalt nitrate, methanol, dichlorotetramine palladium, high-purity graphene, palladium nitrate, sodium borohydride were purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.
[0031] Preparation Example 1:
[0032] The preparation method of Pd-porous graphite specifically includes the following processes:
[0033] 3 parts by weight of 2-methylimidazole were added to 200 parts by weight of methanol to obtain a 2-methylimidazole solution. 1 part by weight of cobalt nitrate was added to 80 parts by weight of methanol to obtain a cobalt nitrate solution. Then, 1 part by weight of the 2-methylimidazole solution was added to 1 part by weight of the cobalt nitrate solution, and stirred at a speed of 20 r / min for 1 h using an automatic stirrer. The mixture was then placed in a ventilated environment and oxidized at a temperature of 20℃ for 24 h. The oxidized mixture was then centrifuged, and the solid material obtained by centrifugation was washed with methanol and dried at 60℃ in a vacuum environment for 12 h to form a composite metal material. The composite metal material was placed in a drying oven and heated to 800℃ at a rate of 5℃ / min, and carbonized at this temperature for 3 h. After cooling, a porous graphite carrier was formed. 12 mg of dichlorotetramine palladium was added to 10 ml of purified water to obtain a dichlorotetramine palladium solution. 1 part by weight of the porous graphite carrier was added to 20 parts by weight of the dichlorotetramine palladium solution and soaked for 12 h. The soaked mixture was then centrifuged, and the solid material obtained by centrifugation was dried at 60℃ in a vacuum environment for 12 h to form Pd-porous graphite.
[0034] Preparation Example 2:
[0035] The preparation method of Pd-porous graphite specifically includes the following processes:
[0036] The 3 parts by weight of 2-methylimidazole is added to 200 parts by weight of methanol to stir evenly to obtain a 2-methylimidazole solution. Then 1 part by weight of cobalt nitrate is added to 80 parts by weight of methanol to stir evenly to obtain a cobalt nitrate solution. Then 1 part by weight of 2-methylimidazole solution is added to 1 part by weight of cobalt nitrate solution, and stirred at a speed of 20 r / min for 1 h by using an automatic stirrer, and then placed in a ventilated environment, controlled at 20℃ for oxidation for 20 h, and the oxidized mixture is centrifuged, and finally the solid material separated by centrifugation is washed with methanol and dried at 60℃ in a vacuum environment for 12 h to form a composite metal material. The composite metal material is placed in a dry oven, heated to 800℃ at a rate of 5℃ / min, and carbonized at this temperature for 3 h, and after cooling, a porous graphite carrier is formed. 12 mg of dichlorotetraammine palladium is added to 10 ml of purified water to obtain a dichlorotetraammine palladium solution. 1 part by weight of porous graphite carrier is added to 20 parts by weight of dichlorotetraammine palladium solution for 12 h of impregnation, and then the impregnated mixture is centrifuged, and finally the solid material separated by centrifugation is dried at 60℃ in a vacuum environment for 12 h to form Pd-porous graphite.
[0037] Preparation Example 3:
[0038] The preparation method of Pd-porous graphite specifically includes the following processes:
[0039] The 3 parts by weight of 2-methylimidazole is added to 200 parts by weight of methanol to stir evenly to obtain a 2-methylimidazole solution. Then 1 part by weight of cobalt nitrate is added to 80 parts by weight of methanol to stir evenly to obtain a cobalt nitrate solution. Then 1 part by weight of 2-methylimidazole solution is added to 1 part by weight of cobalt nitrate solution, and stirred at a speed of 20 r / min for 1 h by using an automatic stirrer, and then placed in a ventilated environment, controlled at 20℃ for oxidation for 24 h, and the oxidized mixture is centrifuged, and finally the solid material separated by centrifugation is washed with methanol and dried at 60℃ in a vacuum environment for 12 h to form a composite metal material. The composite metal material is placed in a dry oven, heated to 600℃ at a rate of 5℃ / min, and carbonized at this temperature for 3 h, and after cooling, a porous graphite carrier is formed. 12 mg of dichlorotetraammine palladium is added to 10 ml of purified water to obtain a dichlorotetraammine palladium solution. 1 part by weight of porous graphite carrier is added to 20 parts by weight of dichlorotetraammine palladium solution for 12 h of impregnation, and then the impregnated mixture is centrifuged, and finally the solid material separated by centrifugation is dried at 60℃ in a vacuum environment for 12 h to form Pd-porous graphite.
[0040] Preparation Example 4:
[0041] The preparation method of Pd-porous graphite specifically includes the following processes:
[0042] Three parts by weight of 2-methylimidazole were added to 200 parts by weight of methanol and stirred until homogeneous to obtain a 2-methylimidazole solution. One part by weight of cobalt nitrate was then added to 80 parts by weight of methanol and stirred until homogeneous to obtain a cobalt nitrate solution. One part by weight of the 2-methylimidazole solution was then added to the cobalt nitrate solution, and the mixture was stirred at 20 rpm for 1 hour using an automatic stirrer. The mixture was then placed in a ventilated environment and oxidized at 20°C for 24 hours. The oxidized mixture was centrifuged, and the solid material was washed with methanol and dried under vacuum at 60°C for 12 hours to form a composite metal material. The composite metal material was placed in a dry oven and heated to 800°C at a rate of 5°C / min, and carbonized at this temperature for 3 hours. After cooling, a porous graphite carrier was formed. 12 mg of dichlorotetraamminepalladium was added to 10 ml of purified water and mixed to obtain a dichlorotetraamminepalladium solution. One part by weight of porous graphite carrier was added to 16 parts by weight of dichlorotetraamminepalladium solution and impregnated for 12 hours. The impregnated mixture was then centrifuged and separated. Finally, the solid material separated by centrifugation was dried in a vacuum environment at 60°C for 12 hours to form Pd-porous graphite.
[0043] Preparation Example 5:
[0044] The preparation method of Pd-porous graphite specifically includes the following steps:
[0045] Three parts by weight of 2-methylimidazole were added to 200 parts by weight of methanol and stirred until homogeneous to obtain a 2-methylimidazole solution. One part by weight of cobalt nitrate was then added to 80 parts by weight of methanol and stirred until homogeneous to obtain a cobalt nitrate solution. The 1 part by weight of the 2-methylimidazole solution was then added to the 1 part by weight of the cobalt nitrate solution, and the mixture was stirred at 20 rpm for 1 hour using an automatic stirrer. The mixture was then placed in a ventilated environment and oxidized at 20°C for 20 hours. The oxidized mixture was centrifuged, and the solid material was washed with methanol and dried under vacuum at 60°C for 12 hours to form a composite metal material. The composite metal material was placed in a dry oven and heated to 600°C at a rate of 5°C / min, and carbonized at this temperature for 3 hours. After cooling, a porous graphite carrier was formed. 12 mg of dichlorotetraamminepalladium was added to 10 ml of purified water and mixed to obtain a dichlorotetraamminepalladium solution. One part by weight of porous graphite carrier was added to 16 parts by weight of dichlorotetraamminepalladium solution and impregnated for 12 hours. The impregnated mixture was then centrifuged and separated. Finally, the solid material separated by centrifugation was dried in a vacuum environment at 60°C for 12 hours to form Pd-porous graphite.
[0046] Preparation Example 6:
[0047] The preparation method of Pd-porous graphite specifically includes the following steps:
[0048] The 3 parts by weight of 2-methylimidazole is added to 200 parts by weight of methanol to stir evenly to obtain a 2-methylimidazole solution. Then 1 part by weight of cobalt nitrate is added to 80 parts by weight of methanol to stir evenly to obtain a cobalt nitrate solution. Then 1 part by weight of 2-methylimidazole solution is added to 1 part by weight of cobalt nitrate solution, and stirred at a speed of 20 r / min for 1 h by using an automatic stirrer, and then placed in a ventilated environment, controlled at 20℃ for oxidation for 18 h, and the oxidized mixture is centrifuged, and finally the solid material separated by centrifugation is washed with methanol and dried at 60℃ in a vacuum environment for 12 h to form a composite metal material. The composite metal material is placed in a dry oven, heated to 600℃ at a rate of 5℃ / min, and carbonized at this temperature for 3 h, and after cooling, a porous graphite carrier is formed. 12 mg of dichlorotetraammine palladium is added to 10 ml of purified water to obtain a dichlorotetraammine palladium solution. 1 part by weight of porous graphite carrier is added to 16 parts by weight of dichlorotetraammine palladium solution for impregnation for 12 h, and then the impregnated mixture is centrifuged, and finally the solid material separated by centrifugation is dried at 60℃ in a vacuum environment for 12 h to form Pd-porous graphite.
[0049] Preparation Example 7:
[0050] The preparation method of Pd-porous graphite specifically includes the following processes:
[0051] The 3 parts by weight of 2-methylimidazole is added to 200 parts by weight of methanol to stir evenly to obtain a 2-methylimidazole solution. Then 1 part by weight of cobalt nitrate is added to 80 parts by weight of methanol to stir evenly to obtain a cobalt nitrate solution. Then 1 part by weight of 2-methylimidazole solution is added to 1 part by weight of cobalt nitrate solution, and stirred at a speed of 20 r / min for 1 h by using an automatic stirrer, and then placed in a ventilated environment, controlled at 20℃ for oxidation for 26 h, and the oxidized mixture is centrifuged, and finally the solid material separated by centrifugation is washed with methanol and dried at 60℃ in a vacuum environment for 12 h to form a composite metal material. The composite metal material is placed in a dry oven, heated to 600℃ at a rate of 5℃ / min, and carbonized at this temperature for 3 h, and after cooling, a porous graphite carrier is formed. 12 mg of dichlorotetraammine palladium is added to 10 ml of purified water to obtain a dichlorotetraammine palladium solution. 1 part by weight of porous graphite carrier is added to 16 parts by weight of dichlorotetraammine palladium solution for impregnation for 12 h, and then the impregnated mixture is centrifuged, and finally the solid material separated by centrifugation is dried at 60℃ in a vacuum environment for 12 h to form Pd-porous graphite.
[0052] Preparation Example 8:
[0053] The preparation method of Pd-porous graphite specifically includes the following processes:
[0054] The 3 parts by weight of 2-methylimidazole is added to 200 parts by weight of methanol to stir evenly to obtain a 2-methylimidazole solution. Then 1 part by weight of cobalt nitrate is added to 80 parts by weight of methanol to stir evenly to obtain a cobalt nitrate solution. Then 1 part by weight of 2-methylimidazole solution is added to 1 part by weight of cobalt nitrate solution, and stirred at a speed of 20 r / min for 1 h by using an automatic stirrer, and then placed in a ventilated environment, controlled at 20℃ for oxidation for 20 h, and the oxidized mixture is centrifuged, and finally the solid material separated by centrifugation is washed with methanol and dried at 60℃ in a vacuum environment for 12 h to form a composite metal material. The composite metal material is placed in a dry oven, heated to 500℃ at a rate of 5℃ / min, and carbonized at this temperature for 3 h, and after cooling, a porous graphite carrier is formed. 12 mg of dichlorotetraammine palladium is added to 10 ml of purified water to obtain a dichlorotetraammine palladium solution. 1 part by weight of porous graphite carrier is added to 16 parts by weight of dichlorotetraammine palladium solution for impregnation for 12 h, and then the impregnated mixture is centrifuged, and finally the solid material separated by centrifugation is dried at 60℃ in a vacuum environment for 12 h to form Pd-porous graphite.
[0055] Preparation Example 9:
[0056] The preparation method of Pd-porous graphite specifically includes the following processes:
[0057] The 3 parts by weight of 2-methylimidazole is added to 200 parts by weight of methanol to stir evenly to obtain a 2-methylimidazole solution. Then 1 part by weight of cobalt nitrate is added to 80 parts by weight of methanol to stir evenly to obtain a cobalt nitrate solution. Then 1 part by weight of 2-methylimidazole solution is added to 1 part by weight of cobalt nitrate solution, and stirred at a speed of 20 r / min for 1 h by using an automatic stirrer, and then placed in a ventilated environment, controlled at 20℃ for oxidation for 20 h, and the oxidized mixture is centrifuged, and finally the solid material separated by centrifugation is washed with methanol and dried at 60℃ in a vacuum environment for 12 h to form a composite metal material. The composite metal material is placed in a dry oven, heated to 900℃ at a rate of 5℃ / min, and carbonized at this temperature for 3 h, and after cooling, a porous graphite carrier is formed. 12 mg of dichlorotetraammine palladium is added to 10 ml of purified water to obtain a dichlorotetraammine palladium solution. 1 part by weight of porous graphite carrier is added to 16 parts by weight of dichlorotetraammine palladium solution for impregnation for 12 h, and then the impregnated mixture is centrifuged, and finally the solid material separated by centrifugation is dried at 60℃ in a vacuum environment for 12 h to form Pd-porous graphite.
[0058] Preparation Example 10:
[0059] The preparation method of Pd-porous graphite specifically includes the following processes:
[0060] The 3 parts by weight of 2-methylimidazole is added to 200 parts by weight of methanol to stir evenly to obtain a 2-methylimidazole solution. Then 1 part by weight of cobalt nitrate is added to 80 parts by weight of methanol to stir evenly to obtain a cobalt nitrate solution. Then 1 part by weight of 2-methylimidazole solution is added to 1 part by weight of cobalt nitrate solution, and stirred with an automatic stirrer at a speed of 20 r / min for 1 h, and then placed in a ventilated environment, controlled at 20℃ for oxidation for 20 h, and the oxidized mixture is centrifuged, and finally the solid material separated by centrifugation is washed with methanol and dried at 60℃ in a vacuum environment for 12 h to form a composite metal material. The composite metal material is placed in a dry oven, heated to 600℃ at a rate of 5℃ / min, and carbonized at this temperature for 3 h, and after cooling, a porous graphite carrier is formed. 12 mg of dichlorotetraammine palladium is added to 10 ml of purified water to obtain a dichlorotetraammine palladium solution. 1 part by weight of the porous graphite carrier is added to 15 parts by weight of the dichlorotetraammine palladium solution and soaked for 12 h, then the soaked mixture is centrifuged, and finally the solid material separated by centrifugation is dried at 60℃ in a vacuum environment for 12 h to form Pd-porous graphite.
[0061] Preparation Example 11:
[0062] The preparation method of Pd-porous graphite specifically includes the following processes:
[0063] The 3 parts by weight of 2-methylimidazole is added to 200 parts by weight of methanol to stir evenly to obtain a 2-methylimidazole solution. Then 1 part by weight of cobalt nitrate is added to 80 parts by weight of methanol to stir evenly to obtain a cobalt nitrate solution. Then 1 part by weight of 2-methylimidazole solution is added to 1 part by weight of cobalt nitrate solution, and stirred with an automatic stirrer at a speed of 20 r / min for 1 h, and then placed in a ventilated environment, controlled at 20℃ for oxidation for 20 h, and the oxidized mixture is centrifuged, and finally the solid material separated by centrifugation is washed with methanol and dried at 60℃ in a vacuum environment for 12 h to form a composite metal material. The composite metal material is placed in a dry oven, heated to 600℃ at a rate of 5℃ / min, and carbonized at this temperature for 3 h, and after cooling, a porous graphite carrier is formed. 12 mg of dichlorotetraammine palladium is added to 10 ml of purified water to obtain a dichlorotetraammine palladium solution. 1 part by weight of the porous graphite carrier is added to 15 parts by weight of the dichlorotetraammine palladium solution and soaked for 12 h, then the soaked mixture is centrifuged, and finally the solid material separated by centrifugation is dried at 60℃ in a vacuum environment for 12 h to form Pd-porous graphite.
[0064] Preparation Example 12:
[0065] The preparation method of Pd-porous graphite specifically includes the following processes:
[0066] The porous graphite carrier in Preparation Example 1 is replaced with high-purity graphene, and the rest of the conditions remain the same as in Preparation Example 1.
[0067] Preparation Example 13:
[0068] The method for preparing Pd- porous graphite specifically includes the following process:
[0069] The dichlorotetrammine palladium in Preparation Example 1 is replaced by palladium nitrate, and the rest of the conditions remain the same as in Preparation Example 1.
[0070] Example 1:
[0071] The method for preparing a high-selectivity dehydrogenation catalyst specifically includes the following process:
[0072] The Pd- porous graphite obtained in Preparation Example 1 is placed into a plasma reactor, and the parameters are adjusted to an environmental pressure of 60 Pa, a current of 1.2 A, and an environmental gas of nitrogen, and after 1 h of reaction, the following is obtained.
[0073] Example 2:
[0074] The method for preparing a high-selectivity dehydrogenation catalyst specifically includes the following process:
[0075] The Pd- porous graphite obtained in Preparation Example 2 is placed into a plasma reactor, and the parameters are adjusted to an environmental pressure of 60 Pa, a current of 1.2 A, and an environmental gas of nitrogen, and after 1 h of reaction, the following is obtained.
[0076] Example 3:
[0077] The method for preparing a high-selectivity dehydrogenation catalyst specifically includes the following process:
[0078] The Pd- porous graphite obtained in Preparation Example 3 is placed into a plasma reactor, and the parameters are adjusted to an environmental pressure of 60 Pa, a current of 1.2 A, and an environmental gas of nitrogen, and after 1 h of reaction, the following is obtained.
[0079] Example 4:
[0080] The method for preparing a high-selectivity dehydrogenation catalyst specifically includes the following process:
[0081] The Pd- porous graphite obtained in Preparation Example 4 is placed into a plasma reactor, and the parameters are adjusted to an environmental pressure of 60 Pa, a current of 1.2 A, and an environmental gas of nitrogen, and after 1 h of reaction, the following is obtained.
[0082] Example 5:
[0083] The method for preparing a high-selectivity dehydrogenation catalyst specifically includes the following process:
[0084] The Pd- porous graphite obtained from Preparation Example 5 was put into a plasma reactor, and the parameters were adjusted to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, to obtain after 1 h of reaction.
[0085] Comparative Example 1:
[0086] A preparation method of a high-selectivity dehydrogenation catalyst, specifically comprising the following processes:
[0087] The Pd- porous graphite obtained from Preparation Example 6 was put into a plasma reactor, and the parameters were adjusted to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, to obtain after 1 h of reaction.
[0088] Comparative Example 2:
[0089] A preparation method of a high-selectivity dehydrogenation catalyst, specifically comprising the following processes:
[0090] The Pd- porous graphite obtained from Preparation Example 7 was put into a plasma reactor, and the parameters were adjusted to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, to obtain after 1 h of reaction.
[0091] Comparative Example 3:
[0092] A preparation method of a high-selectivity dehydrogenation catalyst, specifically comprising the following processes:
[0093] The Pd- porous graphite obtained from Preparation Example 8 was put into a plasma reactor, and the parameters were adjusted to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, to obtain after 1 h of reaction.
[0094] Comparative Example 4:
[0095] A preparation method of a high-selectivity dehydrogenation catalyst, specifically comprising the following processes:
[0096] The Pd- porous graphite obtained from Preparation Example 9 was put into a plasma reactor, and the parameters were adjusted to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, to obtain after 1 h of reaction.
[0097] Comparative Example 5:
[0098] A preparation method of a high-selectivity dehydrogenation catalyst, specifically comprising the following processes:
[0099] The Pd- porous graphite obtained from Preparation Example 10 was put into a plasma reactor, and the parameters were adjusted to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, to obtain after 1 h of reaction.
[0100] Comparative Example 6:
[0101] A preparation method of a high-selectivity dehydrogenation catalyst, specifically comprising the following processes:
[0102] The Pd-porous graphite obtained from Preparation Example 11 is put into a plasma reactor, and parameters are adjusted to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, to obtain after 1 h of reaction.
[0103] Comparative Example 7:
[0104] A preparation method of a high-selectivity dehydrogenation catalyst, specifically comprising the following processes:
[0105] The Pd-porous graphite obtained from Preparation Example 12 is put into a plasma reactor, and parameters are adjusted to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, to obtain after 1 h of reaction.
[0106] Comparative Example 8:
[0107] A preparation method of a high-selectivity dehydrogenation catalyst, specifically comprising the following processes:
[0108] The Pd-porous graphite obtained from Preparation Example 13 is put into a plasma reactor, and parameters are adjusted to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, to obtain after 1 h of reaction.
[0109] Comparative Example 9:
[0110] A preparation method of a high-selectivity dehydrogenation catalyst, specifically comprising the following processes:
[0111] Sodium borohydride solution is obtained by mixing 4 mg of sodium borohydride into 10 ml of purified water. 1 part by weight of the Pd-porous graphite obtained from Preparation Example 1 is added into 20 parts by weight of the sodium borohydride solution, and a reaction mixture is obtained after 30 min of chemical reduction reaction. The reaction mixture is subjected to centrifugal separation, and finally the separated solid substance is dried at 60°C in a vacuum environment for 12 h.
[0112] The dispersion degree of Pd in the high-selectivity dehydrogenation catalysts prepared in Examples 1-5 and Comparative Examples 1-9 is measured by using a chemical adsorption method of carbon monoxide on a chemical adsorption-desorption instrument. 0.1 g of the high-selectivity dehydrogenation catalysts prepared in Examples 1-5 and Comparative Examples 1-9 is respectively mixed with 10 ml of dodecahydro-N-ethylcarbazole, and the dehydrogenation efficiency of the high-selectivity dehydrogenation catalysts prepared in Examples 1-5 and Comparative Examples 1-9 is tested by using a test device as shown in Figure 1 The dehydrogenation efficiency of the high-selectivity dehydrogenation catalysts prepared in Examples 1-5 and Comparative Examples 1-9 is tested at a test temperature of 160°C for 60 min by using a test device as shown in
[0113]
[0114] From the data in the above table, it can be seen that:
[0115] (1) The high-selectivity dehydrogenation catalysts of Examples 1-5 have better Pd dispersion, and can achieve higher dehydrogenation efficiency at a test temperature of 160°C and a test time of 6h.
[0116] (2) From Comparative Examples 1-2, it can be seen that a shorter oxidation time will affect the framework structure of the composite metal material, thereby affecting the Pd dispersion and dehydrogenation efficiency, and when the oxidation time is higher than 24h, the effect on the performance of the dehydrogenation catalyst tends to be stable, and considering the cost factor, the reasonable range of the oxidation reaction is set to 20h-24h.
[0117] (3) From Comparative Examples 3-4, it can be seen that a lower or higher carbonization temperature will affect the formation of the porous structure of graphite, thereby reducing the Pd dispersion and dehydrogenation efficiency of the dehydrogenation catalyst.
[0118] (4) From Comparative Examples 5-6, it can be seen that the loading of active components by the porous graphite has a suitable range, and less palladium dichloride tetraamine solution cannot reach the upper limit of the loading capacity, thereby reducing the dehydrogenation efficiency of the dehydrogenation catalyst under the same mass, and more palladium dichloride tetraamine solution will cause the active components to aggregate, thereby reducing the contact area with the dodecahydro-N-ethylcarbazole, and affecting the dehydrogenation efficiency.
[0119] (5) From Comparative Example 7, it can be seen that the related performance of the porous graphite carrier described in the present patent is obviously better than that of ordinary porous graphene.
[0120] (6) From Comparative Example 8, it can be seen that the catalytic selectivity of the palladium dichloride tetraamine solution for dodecahydro-N-ethylcarbazole is obviously better than that of palladium nitrate.
[0121] (7) From Comparative Example 9, it can be seen that the combination effect of the discharge reduction method described in the present patent for the active components and the carrier is obviously better than that of the chemical reduction method of sodium borohydride.
[0122] The above-described examples have described the technical solutions and beneficial effects of the present application in detail, and it should be understood that the above-described only the specific embodiments of the present application, and is not used to limit the present application. Without departing from the spirit and scope of the present application, the present application will have various changes and improvements, and these changes and improvements all fall within the scope of the claimed present application.
Claims
1. A method for producing a high-selectivity dehydrogenation catalyst, characterized by, The preparation method comprises the following steps: The Pd-porous graphite is obtained by a plasma discharge reduction reaction, and the high-selectivity dehydrogenation catalyst is obtained; The preparation method of the Pd-porous graphite comprises the following steps: The porous graphite carrier is immersed in a dichlorotetraammine palladium solution for 12 hours, then centrifuged, and finally vacuum dried to obtain the Pd-porous graphite; The preparation method of the porous graphite carrier comprises the following steps: 2-methyl imidazole is added to a methanol solution to obtain a 2-methyl imidazole solution; Cobalt nitrate is added to a methanol solution to obtain a cobalt nitrate solution; The 2-methyl imidazole solution is added to the cobalt nitrate solution to mix and react, then centrifuged, washed with a methanol solution, and finally vacuum dried to obtain a composite metal material; The composite metal material is heated to 600-800℃ at a speed of 5℃ / min, carbonized at this temperature for 3 hours, and cooled to obtain the porous graphite carrier.
2. The method for preparing a highly selective dehydrogenation catalyst according to claim 1, characterized in that, The 2-methyl imidazole solution is obtained by mixing 2-methyl imidazole and a methanol solution according to a weight ratio of 3:
200.
3. The method for preparing a highly selective dehydrogenation catalyst according to claim 1, characterized in that, The cobalt nitrate solution is obtained by mixing cobalt nitrate and a methanol solution according to a weight ratio of 1:
80.
4. The method for preparing a highly selective dehydrogenation catalyst according to claim 1, characterized in that, The weight ratio of the 2-methyl imidazole solution and the cobalt nitrate solution is 1:
1.
5. The method for preparing a highly selective dehydrogenation catalyst according to claim 1, characterized in that, The step of adding the 2-methyl imidazole solution to the cobalt nitrate solution to mix and react comprises stirring at a speed of 20r / min for 1 hour, and then oxidizing at 20℃ for 20-24 hours.
6. The method for preparing a highly selective dehydrogenation catalyst according to claim 1, characterized in that, The weight ratio of the porous graphite carrier and the dichlorotetraammine palladium solution is 1:16-20.
7. The method for preparing a highly selective dehydrogenation catalyst according to claim 1, characterized in that, The conditions of the plasma discharge reduction reaction comprise an environmental pressure of 60Pa, a current of 1.2A, an environmental gas of nitrogen, and a reaction time of 1 hour.
8. A high-selectivity dehydrogenation catalyst prepared by the preparation method of any one of claims 1-7.
9. Use of a highly selective dehydrogenation catalyst according to claim 8 in the field of catalyzing the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, The application conditions comprise adding 0.1g of the high-selectivity dehydrogenation catalyst to every ten milliliters of twelve hydrogen-N-ethyl carbazole, and then reacting at a test temperature of 160℃ for 6 hours.
Citation Information
Patent Citations
In-situ preparation method of mesoporous carbon-loaded palladium nanocatalyst
CN107213896A