High-selectivity dehydrogenation catalyst and preparation method thereof

Abstract

The invention discloses a high-selectivity dehydrogenation catalyst as well as a preparation method and application thereof, and belongs to the technical field of preparation of organic liquid dehydrogenation catalysts. The preparation method comprises the following steps: taking porous graphite as a carrier, and combining with a palladium element through a discharge reduction reaction. The preparation method comprises the following steps: mixing 2-methylimidazole and cobalt nitrate as main materials to obtain a composite metal material, carrying out carbonization treatment on the composite metal material to obtain a porous graphite carrier with excellent performance, dipping the porous graphite carrier in a tetraammine dichloropalladium solution, and adding a palladium element to the porous graphite carrier, so as to obtain the catalyst. And finally, loading the palladium element on the porous graphite carrier through a discharge reduction reaction to form the dehydrogenation catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of organic liquid dehydrogenation catalysts, and particularly relates to a highly selective dehydrogenation catalyst, a preparation method thereof and an application thereof. Background Art

[0002] As an excellent organic liquid hydrogen storage raw material, N-ethylcarbazole has the advantages of easy hydrogenation and dehydrogenation. After hydrogenation, it obtains dodecahydro-N-ethylcarbazole. The hydrogenation and dehydrogenation conditions using N-ethylcarbazole as the hydrogen storage raw material are relatively mild, with low reaction heat, high hydrogen storage rate, low toxicity and good stability, and are attracting more and more attention. At present, many research institutes are actively developing organic liquid hydrogen storage materials mainly based on N-ethylcarbazole. However, when dodecahydro-N-ethylcarbazole obtained after hydrogenation is dehydrogenated, it needs the catalytic action of a catalyst to achieve a good dehydrogenation effect. A good dehydrogenation catalyst can not only effectively remove hydrogen, but also reduce the dehydrogenation temperature and the dehydrogenation cost.

[0003] The carrier and the active component are important components of the catalyst. The carrier mainly plays the roles of carrying and dispersing the active component and the promoter, serving as a framework support, and can also endow the catalyst with basic physical structures and properties, such as pore structure, specific surface area, macroscopic shape and mechanical strength, etc. The active component mainly plays the role of contacting with the organic liquid and catalyzing the dehydrogenation reaction. Within a certain range, the higher the dispersion degree of the active component on the carrier and the more the number of active sites, the higher the activity of the catalyst. For the dehydrogenation catalyst, the carrier should have a large specific surface area, a concentrated pore size distribution and a suitable interaction force with the active component, etc. A high-quality catalyst carrier can greatly improve the catalytic effect of the catalyst.

[0004] Patent CN111054382B discloses a catalyst for the dehydrogenation reaction of organic liquid hydrogen storage materials and a preparation method thereof. The catalyst used is a catalyst containing a platinum group element or its oxide, wherein the dispersion degree of Pt is not less than 21%; by weight, it includes the following components: a) 0.1 to 4.8 parts of a platinum group element or its oxide, b) 0.1 to 6.5 parts of an alkali metal or its oxide, c) 0.1 to 9.6 parts of Ba and / or Sc or their oxides, d) 80 to 99 parts of a carrier S, and S is selected from Fe-Al-O or Fe-Al-Zr-O composite oxides, thereby realizing the dehydrogenation reaction catalysis.

[0005] Although the above patent realizes the dehydrogenation reaction catalysis, it has low selectivity for dodecahydro-N-ethylcarbazole, a long catalytic reaction time and a low dehydrogenation rate. Therefore, developing a catalyst with high selectivity for dodecahydro-N-ethylcarbazole, short catalytic reaction time and high dehydrogenation rate can effectively reduce the cost, which is of great significance. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention uses 2-methylimidazole and cobalt nitrate as the main raw materials. After mixing, a composite metal material is obtained. The composite metal material is carbonized to obtain a porous graphite support with excellent performance. Then, the porous graphite support is impregnated in a palladium dichloride tetraammine solution to add palladium elements to the porous graphite support. Finally, the palladium elements are loaded onto the porous graphite support through an electroreduction reaction to form a dehydrogenation catalyst, solving the technical problems proposed in the background art. Specifically, the technical solution of the present invention includes the following content:

[0007] A preparation method of a highly selective dehydrogenation catalyst, the preparation method comprising the following steps:

[0008] The highly selective dehydrogenation catalyst is obtained by subjecting Pd-porous graphite to a plasma discharge reduction reaction.

[0009] Further, the preparation method of the Pd-porous graphite comprises the following steps:

[0010] The porous graphite support is placed in a palladium dichloride tetraammine solution and impregnated for 12 h, then centrifuged and finally vacuum dried to obtain the Pd-porous graphite;

[0011] The preparation method of the porous graphite support comprises the following steps:

[0012] 2-Methylimidazole is added to a methanol solution and stirred to obtain a 2-methylimidazole solution;

[0013] Cobalt nitrate is added to a methanol solution and stirred to obtain a cobalt nitrate solution;

[0014] The 2-methylimidazole solution is added to the cobalt nitrate solution, and after mixing and reacting, it is centrifuged, then washed with a methanol solution, and finally vacuum dried to obtain a composite metal material;

[0015] The composite metal material is heated to 600-800 °C at a rate of 5 °C / min and carbonized at this temperature for 3 h, and after cooling, the porous graphite support is obtained.

[0016] Further, the 2-methylimidazole solution is obtained by mixing 2-methylimidazole and a methanol solution in a weight ratio of 3:200.

[0017] Further, the cobalt nitrate solution is obtained by mixing cobalt nitrate and a methanol solution in a weight ratio of 1:80.

[0018] Further, the weight ratio of the 2-methylimidazole solution to the cobalt nitrate solution is 1:1.

[0019] Further, the step of adding the 2-methylimidazole solution to the cobalt nitrate solution for mixing reaction includes stirring at a rotation speed of 20 r / min for 1 h and then oxidizing at 20°C for 20 h to 24 h.

[0020] Further, the dichlorotetraamminepalladium solution is obtained by mixing dichlorotetraamminepalladium and purified water in a weight ratio of 3:2500.

[0021] Further, the weight ratio of the porous graphite support to the dichlorotetraamminepalladium solution is 1:16 to 20.

[0022] Further, the conditions of the plasma discharge reduction reaction include an ambient pressure of 60 Pa, a current of 1.2 A, an ambient gas of nitrogen, and a reaction time of 1 h.

[0023] A highly selective dehydrogenation catalyst prepared by a preparation method of a highly selective dehydrogenation catalyst.

[0024] An application of a highly selective dehydrogenation catalyst in the field of catalyzing the dehydrogenation of dodecahydro-N-ethylcarbazole. The conditions of the application include adding 0.1 g of the highly selective dehydrogenation catalyst to every ten milliliters of dodecahydro-N-ethylcarbazole and then reacting at a test temperature of 160°C for 6 h.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] The present invention first uses 2-methylimidazole and cobalt nitrate as the main materials to obtain a basic metal framework, and then obtains a special porous graphite through a carbonization reaction. The good hardness, thermal conductivity, and excellent and stable porous structure of the porous graphite are used as the support of the dehydrogenation catalyst. Then, using the dichlorotetraamminepalladium solution as the raw material, its high selectivity for dodecahydro-N-ethylcarbazole is used as the active component of the dehydrogenation catalyst. Finally, a special discharge reduction reaction is used to replace the conventional chemical discharge reaction, further improving the dispersion degree and stability of the active component in the support, thereby obtaining a dehydrogenation catalyst with high selectivity, high catalytic efficiency, and high dehydrogenation rate. Description of the Drawings

[0027] Figure 1 A test device for testing the highly selective dehydrogenation catalyst prepared by the present invention. Detailed Embodiments

[0028] Next, through the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present invention.

[0029] Unless otherwise specified, the raw materials and reagents used in the present invention hereinafter are all commercially available products or can be prepared by known methods.

[0030] 2-Methylimidazole, cobalt nitrate, methanol, dichlorotetraammine palladium, high-purity graphene, palladium nitrate, and sodium borohydride were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0031] Preparation Example 1:

[0032] A preparation method of Pd-porous graphite specifically includes the following process:

[0033] Add 3 parts by weight of 2-methylimidazole to 200 parts by weight of methanol and stir evenly to obtain a 2-methylimidazole solution. Then add 1 part by weight of cobalt nitrate to 80 parts by weight of methanol and stir evenly to obtain a cobalt nitrate solution. Then add 1 part by weight of the 2-methylimidazole solution to 1 part by weight of the cobalt nitrate solution, stir with an automatic stirrer at a speed of 20 r / min for 1 h, then place it in a ventilated environment, control the temperature at 20 °C for oxidation for 24 h, and centrifuge the oxidized mixture. Finally, wash the solid material separated by centrifugation with methanol and dry it in a vacuum environment at 60 °C for 12 h to form a composite metal material. Place the composite metal material in a drying oven, heat it to 800 °C at a rate of 5 °C / min, and carbonize it at this temperature for 3 h. After cooling, a porous graphite support is formed. Add 12 mg of dichlorotetraammine palladium to 10 ml of purified water and mix to obtain a dichlorotetraammine palladium solution. Add 1 part by weight of the porous graphite support to 20 parts by weight of the dichlorotetraammine palladium solution and impregnate for 12 h, then centrifuge the impregnated mixture. Finally, dry the solid material separated by centrifugation in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0034] Preparation Example 2:

[0035] A preparation method of Pd-porous graphite specifically includes the following process:

[0036] 3 parts by weight of 2-methylimidazole was added to 200 parts by weight of methanol and stirred evenly to obtain a 2-methylimidazole solution. Then, 1 part by weight of cobalt nitrate was added to 80 parts by weight of methanol and stirred evenly to obtain a cobalt nitrate solution. Next, 1 part by weight of the 2-methylimidazole solution was added to 1 part by weight of the cobalt nitrate solution, and the mixture was stirred at a speed of 20 r / min for 1 h using an automatic stirrer. Then, it was placed in a ventilated environment, oxidized at a controlled temperature of 20 °C for 20 h, and the oxidized mixture was centrifuged. Finally, the solid matter separated by centrifugation was washed with methanol and dried in a vacuum environment at 60 °C for 12 h to form a composite metal material. The composite metal material was placed in an oven and heated to 800 °C at a rate of 5 °C / min, and carbonized at this temperature for 3 h. After cooling, a porous graphite support was formed. 12 mg of palladium diamminedichloride was added to 10 ml of purified water and mixed to obtain a palladium diamminedichloride solution. 1 part by weight of the porous graphite support was added to 20 parts by weight of the palladium diamminedichloride solution and impregnated for 12 h. Then, the impregnated mixture was centrifuged. Finally, the solid matter separated by centrifugation was dried in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0037] Preparation Example 3:

[0038] A method for preparing Pd-porous graphite, specifically including the following process:

[0039] 3 parts by weight of 2-methylimidazole was added to 200 parts by weight of methanol and stirred evenly to obtain a 2-methylimidazole solution. Then, 1 part by weight of cobalt nitrate was added to 80 parts by weight of methanol and stirred evenly to obtain a cobalt nitrate solution. Next, 1 part by weight of the 2-methylimidazole solution was added to 1 part by weight of the cobalt nitrate solution, and the mixture was stirred at a speed of 20 r / min for 1 h using an automatic stirrer. Then, it was placed in a ventilated environment, oxidized at a controlled temperature of 20 °C for 24 h, and the oxidized mixture was centrifuged. Finally, the solid matter separated by centrifugation was washed with methanol and dried in a vacuum environment at 60 °C for 12 h to form a composite metal material. The composite metal material was placed in an oven and heated to 600 °C at a rate of 5 °C / min, and carbonized at this temperature for 3 h. After cooling, a porous graphite support was formed. 12 mg of palladium diamminedichloride was added to 10 ml of purified water and mixed to obtain a palladium diamminedichloride solution. 1 part by weight of the porous graphite support was added to 20 parts by weight of the palladium diamminedichloride solution and impregnated for 12 h. Then, the impregnated mixture was centrifuged. Finally, the solid matter separated by centrifugation was dried in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0040] Preparation Example 4:

[0041] A method for preparing Pd-porous graphite, specifically including the following process:

[0042] 3 parts by weight of 2-methylimidazole was added to 200 parts by weight of methanol and stirred evenly to obtain a 2-methylimidazole solution. Then, 1 part by weight of cobalt nitrate was added to 80 parts by weight of methanol and stirred evenly to obtain a cobalt nitrate solution. Next, 1 part by weight of the 2-methylimidazole solution was added to 1 part by weight of the cobalt nitrate solution, and the mixture was stirred at a speed of 20 r / min for 1 h using an automatic stirrer. Then, it was placed in a ventilated environment, oxidized at a controlled temperature of 20 °C for 24 h, and the oxidized mixture was centrifuged. Finally, the solid material separated by centrifugation was washed with methanol and dried in a vacuum environment at 60 °C for 12 h to form a composite metal material. The composite metal material was placed in an oven and heated to 800 °C at a rate of 5 °C / min, and carbonized at this temperature for 3 h. After cooling, a porous graphite support was formed. 12 mg of palladium diammine dichloride was added to 10 ml of purified water and mixed to obtain a palladium diammine dichloride solution. 1 part by weight of the porous graphite support was added to 16 parts by weight of the palladium diammine dichloride solution and impregnated for 12 h. Then, the impregnated mixture was centrifuged. Finally, the solid material separated by centrifugation was dried in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0043] Preparation Example 5:

[0044] A method for preparing Pd-porous graphite, specifically including the following process:

[0045] 3 parts by weight of 2-methylimidazole was added to 200 parts by weight of methanol and stirred evenly to obtain a 2-methylimidazole solution. Then, 1 part by weight of cobalt nitrate was added to 80 parts by weight of methanol and stirred evenly to obtain a cobalt nitrate solution. Next, 1 part by weight of the 2-methylimidazole solution was added to 1 part by weight of the cobalt nitrate solution, and the mixture was stirred at a speed of 20 r / min for 1 h using an automatic stirrer. Then, it was placed in a ventilated environment, oxidized at a controlled temperature of 20 °C for 20 h, and the oxidized mixture was centrifuged. Finally, the solid material separated by centrifugation was washed with methanol and dried in a vacuum environment at 60 °C for 12 h to form a composite metal material. The composite metal material was placed in an oven and heated to 600 °C at a rate of 5 °C / min, and carbonized at this temperature for 3 h. After cooling, a porous graphite support was formed. 12 mg of palladium diammine dichloride was added to 10 ml of purified water and mixed to obtain a palladium diammine dichloride solution. 1 part by weight of the porous graphite support was added to 16 parts by weight of the palladium diammine dichloride solution and impregnated for 12 h. Then, the impregnated mixture was centrifuged. Finally, the solid material separated by centrifugation was dried in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0046] Preparation Example 6:

[0047] A method for preparing Pd-porous graphite, specifically including the following process:

[0048] 3 parts by weight of 2-methylimidazole was added to 200 parts by weight of methanol and stirred evenly to obtain a 2-methylimidazole solution. Then, 1 part by weight of cobalt nitrate was added to 80 parts by weight of methanol and stirred evenly to obtain a cobalt nitrate solution. Next, 1 part by weight of the 2-methylimidazole solution was added to 1 part by weight of the cobalt nitrate solution, and the mixture was stirred at a speed of 20 r / min for 1 h using an automatic stirrer. Then, it was placed in a ventilated environment, oxidized at a controlled temperature of 20 °C for 18 h, and the oxidized mixture was centrifuged. Finally, the solid matter separated by centrifugation was washed with methanol and dried in a vacuum environment at 60 °C for 12 h to form a composite metal material. The composite metal material was placed in a drying oven and heated to 600 °C at a rate of 5 °C / min, and carbonized at this temperature for 3 h. After cooling, a porous graphite support was formed. 12 mg of palladium diamminedichloride was added to 10 ml of purified water and mixed to obtain a palladium diamminedichloride solution. 1 part by weight of the porous graphite support was added to 16 parts by weight of the palladium diamminedichloride solution and impregnated for 12 h. Then, the impregnated mixture was centrifuged. Finally, the solid matter separated by centrifugation was dried in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0049] Preparation Example 7:

[0050] A method for preparing Pd-porous graphite, specifically including the following process:

[0051] 3 parts by weight of 2-methylimidazole was added to 200 parts by weight of methanol and stirred evenly to obtain a 2-methylimidazole solution. Then, 1 part by weight of cobalt nitrate was added to 80 parts by weight of methanol and stirred evenly to obtain a cobalt nitrate solution. Next, 1 part by weight of the 2-methylimidazole solution was added to 1 part by weight of the cobalt nitrate solution, and the mixture was stirred at a speed of 20 r / min for 1 h using an automatic stirrer. Then, it was placed in a ventilated environment, oxidized at a controlled temperature of 20 °C for 26 h, and the oxidized mixture was centrifuged. Finally, the solid matter separated by centrifugation was washed with methanol and dried in a vacuum environment at 60 °C for 12 h to form a composite metal material. The composite metal material was placed in a drying oven and heated to 600 °C at a rate of 5 °C / min, and carbonized at this temperature for 3 h. After cooling, a porous graphite support was formed. 12 mg of palladium diamminedichloride was added to 10 ml of purified water and mixed to obtain a palladium diamminedichloride solution. 1 part by weight of the porous graphite support was added to 16 parts by weight of the palladium diamminedichloride solution and impregnated for 12 h. Then, the impregnated mixture was centrifuged. Finally, the solid matter separated by centrifugation was dried in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0052] Preparation Example 8:

[0053] A method for preparing Pd-porous graphite, specifically including the following process:

[0054] 3 parts by weight of 2-methylimidazole was added to 200 parts by weight of methanol and stirred evenly to obtain a 2-methylimidazole solution. Then, 1 part by weight of cobalt nitrate was added to 80 parts by weight of methanol and stirred evenly to obtain a cobalt nitrate solution. Next, 1 part by weight of the 2-methylimidazole solution was added to 1 part by weight of the cobalt nitrate solution, and the mixture was stirred at a speed of 20 r / min for 1 h using an automatic stirrer. Then, it was placed in a ventilated environment, oxidized at 20 °C for 20 h, and the oxidized mixture was centrifuged. Finally, the solid material separated by centrifugation was washed with methanol and dried in a vacuum environment at 60 °C for 12 h to form a composite metal material. The composite metal material was placed in a drying oven, heated to 500 °C at a rate of 5 °C / min, and carbonized at this temperature for 3 h. After cooling, a porous graphite support was formed. 12 mg of palladium diamminedichloride was added to 10 ml of purified water and mixed to obtain a palladium diamminedichloride solution. 1 part by weight of the porous graphite support was added to 16 parts by weight of the palladium diamminedichloride solution and impregnated for 12 h. Then, the impregnated mixture was centrifuged. Finally, the solid material separated by centrifugation was dried in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0055] Preparation Example 9:

[0056] A method for preparing Pd-porous graphite, specifically including the following process:

[0057] 3 parts by weight of 2-methylimidazole was added to 200 parts by weight of methanol and stirred evenly to obtain a 2-methylimidazole solution. Then, 1 part by weight of cobalt nitrate was added to 80 parts by weight of methanol and stirred evenly to obtain a cobalt nitrate solution. Next, 1 part by weight of the 2-methylimidazole solution was added to 1 part by weight of the cobalt nitrate solution, and the mixture was stirred at a speed of 20 r / min for 1 h using an automatic stirrer. Then, it was placed in a ventilated environment, oxidized at 900 °C for 20 h, and the oxidized mixture was centrifuged. Finally, the solid material separated by centrifugation was washed with methanol and dried in a vacuum environment at 60 °C for 12 h to form a composite metal material. The composite metal material was placed in a drying oven, heated to 900 °C at a rate of 5 °C / min, and carbonized at this temperature for 3 h. After cooling, a porous graphite support was formed. 12 mg of palladium diamminedichloride was added to 10 ml of purified water and mixed to obtain a palladium diamminedichloride solution. 1 part by weight of the porous graphite support was added to 16 parts by weight of the palladium diamminedichloride solution and impregnated for 12 h. Then, the impregnated mixture was centrifuged. Finally, the solid material separated by centrifugation was dried in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0058] Preparation Example 10:

[0059] A method for preparing Pd-porous graphite, specifically including the following process:

[0060] Add 3 parts by weight of 2-methylimidazole to 200 parts by weight of methanol and stir evenly to obtain a 2-methylimidazole solution. Then add 1 part by weight of cobalt nitrate to 80 parts by weight of methanol and stir evenly to obtain a cobalt nitrate solution. Next, add 1 part by weight of the 2-methylimidazole solution to 1 part by weight of the cobalt nitrate solution, stir with a magnetic stirrer at a speed of 20 r / min for 1 h, then place it in a ventilated environment, oxidize at a controlled temperature of 20 °C for 20 h, and centrifuge the oxidized mixture. Finally, wash the solid material separated by centrifugation with methanol and dry it in a vacuum environment at 60 °C for 12 h to form a composite metal material. Place the composite metal material in a drying oven, heat it to 600 °C at a rate of 5 °C / min, and carbonize it at this temperature for 3 h. After cooling, a porous graphite support is formed. Add 12 mg of palladium dichloride tetraammine to 10 ml of purified water and mix to obtain a palladium dichloride tetraammine solution. Add 1 part by weight of the porous graphite support to 15 parts by weight of the palladium dichloride tetraammine solution and impregnate for 12 h. Then centrifuge the impregnated mixture. Finally, dry the solid material separated by centrifugation in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0061] Preparation Example 11:

[0062] A method for preparing Pd-porous graphite, specifically including the following process:

[0063] Add 3 parts by weight of 2-methylimidazole to 200 parts by weight of methanol and stir evenly to obtain a 2-methylimidazole solution. Then add 1 part by weight of cobalt nitrate to 80 parts by weight of methanol and stir evenly to obtain a cobalt nitrate solution. Next, add 1 part by weight of the 2-methylimidazole solution to 1 part by weight of the cobalt nitrate solution, stir with a magnetic stirrer at a speed of 20 r / min for 1 h, then place it in a ventilated environment, oxidize at a controlled temperature of 20 °C for 20 h, and centrifuge the oxidized mixture. Finally, wash the solid material separated by centrifugation with methanol and dry it in a vacuum environment at 60 °C for 12 h to form a composite metal material. Place the composite metal material in a drying oven, heat it to 600 °C at a rate of 5 °C / min, and carbonize it at this temperature for 3 h. After cooling, a porous graphite support is formed. Add 12 mg of palladium dichloride tetraammine to 10 ml of purified water and mix to obtain a palladium dichloride tetraammine solution. Add 1 part by weight of the porous graphite support to 22 parts by weight of the palladium dichloride tetraammine solution and impregnate for 12 h. Then centrifuge the impregnated mixture. Finally, dry the solid material separated by centrifugation in a vacuum environment at 60 °C for 12 h to form Pd-porous graphite.

[0064] Preparation Example 12:

[0065] A method for preparing Pd-porous graphite, specifically including the following process:

[0066] Replace the porous graphite support in Preparation Example 1 with high-purity graphene, and keep the other conditions the same as those in Preparation Example 1.

[0067] Preparation Example 13:

[0068] A method for preparing Pd-porous graphite, specifically including the following process:

[0069] Replace the palladium dichloride tetraammine in Preparation Example 1 with palladium nitrate, and keep the other conditions the same as those in Preparation Example 1.

[0070] Example 1:

[0071] A method for preparing a highly selective dehydrogenation catalyst, specifically including the following process:

[0072] Put the Pd-porous graphite obtained in Preparation Example 1 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0073] Example 2:

[0074] A method for preparing a highly selective dehydrogenation catalyst, specifically including the following process:

[0075] Put the Pd-porous graphite obtained in Preparation Example 2 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0076] Example 3:

[0077] A method for preparing a highly selective dehydrogenation catalyst, specifically including the following process:

[0078] Put the Pd-porous graphite obtained in Preparation Example 3 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0079] Example 4:

[0080] A method for preparing a highly selective dehydrogenation catalyst, specifically including the following process:

[0081] Put the Pd-porous graphite obtained in Preparation Example 4 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0082] Example 5:

[0083] A method for preparing a highly selective dehydrogenation catalyst, specifically including the following process:

[0084] Put the Pd-porous graphite obtained in Preparation Example 5 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0085] Comparative Example 1:

[0086] A preparation method of a highly selective dehydrogenation catalyst specifically includes the following process:

[0087] Put the Pd-porous graphite obtained in Preparation Example 6 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0088] Comparative Example 2:

[0089] A preparation method of a highly selective dehydrogenation catalyst specifically includes the following process:

[0090] Put the Pd-porous graphite obtained in Preparation Example 7 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0091] Comparative Example 3:

[0092] A preparation method of a highly selective dehydrogenation catalyst specifically includes the following process:

[0093] Put the Pd-porous graphite obtained in Preparation Example 8 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0094] Comparative Example 4:

[0095] A preparation method of a highly selective dehydrogenation catalyst specifically includes the following process:

[0096] Put the Pd-porous graphite obtained in Preparation Example 9 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0097] Comparative Example 5:

[0098] A preparation method of a highly selective dehydrogenation catalyst specifically includes the following process:

[0099] Put the Pd-porous graphite obtained in Preparation Example 10 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0100] Comparative Example 6:

[0101] A preparation method of a highly selective dehydrogenation catalyst, specifically including the following process:

[0102] Put the Pd-porous graphite obtained in Preparation Example 11 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0103] Comparative Example 7:

[0104] A preparation method of a highly selective dehydrogenation catalyst, specifically including the following process:

[0105] Put the Pd-porous graphite obtained in Preparation Example 12 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0106] Comparative Example 8:

[0107] A preparation method of a highly selective dehydrogenation catalyst, specifically including the following process:

[0108] Put the Pd-porous graphite obtained in Preparation Example 13 into a plasma reactor, adjust the parameters to ambient pressure: 60 Pa; current: 1.2 A; ambient gas: nitrogen, and obtain it after reacting for 1 h.

[0109] Comparative Example 9:

[0110] A preparation method of a highly selective dehydrogenation catalyst, specifically including the following process:

[0111] Add 4 mg of sodium borohydride to 10 ml of purified water to obtain a sodium borohydride solution. Add 1 part by weight of the Pd-porous graphite obtained in Preparation Example 1 to 20 parts by weight of the sodium borohydride solution, carry out a chemical reduction reaction for 30 min to obtain a reaction mixture, centrifuge the reaction mixture, and finally dry the separated solid substance in a vacuum environment at 60 °C for 12 h to obtain.

[0112] Respectively take 0.1 g of the highly selective dehydrogenation catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 9, and measure the dispersion of Pd in the catalyst by carbon monoxide chemisorption method on a chemisorption instrument. Then take 0.1 g of the highly selective dehydrogenation catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 9 and mix them with 10 ml of dodecahydro-N-ethylcarbazole respectively, and pass through Figure 1 The shown test device, and test the dehydrogenation efficiency of the highly selective dehydrogenation catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 9 respectively at a test temperature of 160 °C for 60 min. The test results are as follows in the table:

[0113]

[0114] As can be seen from the data in the above table:

[0115] (1) The highly selective dehydrogenation catalysts of Examples 1-5 have relatively good Pd dispersion, and at a test temperature of 160 °C and a test time of 6 h, a relatively high dehydrogenation efficiency can be achieved.

[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 Pd dispersion and dehydrogenation efficiency. When the oxidation time is higher than 24 h, the influence on the performance of the dehydrogenation catalyst tends to be stable. Considering cost factors, the reasonable range of the oxidation reaction is set at 20 h - 24 h.

[0117] (3) From Comparative Examples 3-4, it can be seen that both too low or too high carbonization temperature will affect the formation of the graphite porous structure, thereby reducing the Pd dispersion and dehydrogenation efficiency of the dehydrogenation catalyst.

[0118] (4) From Comparative Examples 5-6, it can be seen that there is a suitable range for the loading of active components on porous graphite. Too little palladium diammine dichloride solution cannot reach the upper limit of the loading capacity, thereby reducing the dehydrogenation efficiency of the dehydrogenation catalyst under the same mass. Too much palladium diammine dichloride solution will cause the active components to polymerize, thereby reducing the contact area with dodecahydro-N-ethylcarbazole and affecting the dehydrogenation efficiency.

[0119] (5) From Comparative Example 7, it can be seen that the relevant properties of the porous graphite carrier described in this patent are significantly better than those of ordinary porous graphene.

[0120] (6) From Comparative Example 8, it can be seen that the catalytic selectivity of palladium diammine dichloride solution for dodecahydro-N-ethylcarbazole is significantly better than that of palladium nitrate.

[0121] (7) From Comparative Example 9, it can be seen that the discharge reduction method described in this patent has a significantly better binding effect of active components to the carrier than the chemical reduction method with sodium borohydride.

[0122] The above-described embodiments have detailed the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for preparing a highly selective dehydrogenation catalyst, characterized in that: The preparation method comprises the following steps: The high-selectivity dehydrogenation catalyst is obtained by plasma discharge reduction reaction of Pd-porous graphite.

2. The method for preparing a highly selective dehydrogenation catalyst according to claim 1, characterized in that: The preparation method of the Pd-porous graphite comprises the following steps: The porous graphite carrier is immersed in a dichlorotetraamminepalladium 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-methylimidazole is added to the methanol solution and stirred to obtain a 2-methylimidazole solution; Cobalt nitrate is added into the methanol solution and stirred to obtain a cobalt nitrate solution; The 2-methylimidazole solution is added to the cobalt nitrate solution for mixed reaction, and then centrifuged and separated, and then washed with a methanol solution, and finally vacuum dried to obtain a composite metal material; The composite metal material is heated to 600-800° C. at a rate of 5° C. / min, and carbonized at this temperature for 3 hours, and then cooled to obtain the porous graphite carrier.

3. The method for preparing a highly selective dehydrogenation catalyst according to claim 2, characterized in that: The 2-methylimidazole solution is obtained by mixing 2-methylimidazole and methanol solution in a weight ratio of 3:

200.

4. The method for preparing a highly selective dehydrogenation catalyst according to claim 2, characterized in that: The cobalt nitrate solution is obtained by mixing cobalt nitrate and methanol solution in a weight ratio of 1:

80.

5. The method for preparing a highly selective dehydrogenation catalyst according to claim 2, characterized in that: The weight ratio of the 2-methylimidazole solution to the cobalt nitrate solution is 1:

1.

6. The method for preparing a highly selective dehydrogenation catalyst according to claim 2, characterized in that: The step of adding the 2-methylimidazole solution to the cobalt nitrate solution for mixed reaction comprises stirring at a speed of 20 r / min for 1 hour, and then placing in an environment of 20° C. for oxidation for 20 to 24 hours.

7. The method for preparing a highly selective dehydrogenation catalyst according to claim 2, characterized in that: The weight ratio of the porous graphite carrier to the dichlorotetraamminepalladium solution is 1:16-20.

8. The method for preparing a highly selective dehydrogenation catalyst according to claim 1, characterized in that: The conditions of the plasma discharge reduction reaction include an ambient pressure of 60 Pa, a current of 1.2 A, an ambient gas of nitrogen, and a reaction time of 1 h.

9. A highly selective dehydrogenation catalyst prepared by the method for preparing a highly selective dehydrogenation catalyst according to any one of claims 1 to 8.

10. Use of the highly selective dehydrogenation catalyst as claimed in claim 9 in the field of catalytic dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that: The application conditions include adding 0.1 g of the highly selective dehydrogenation catalyst per 10 ml of dodecahydro-N-ethylcarbazole, and reacting at a test temperature of 160° C. for 6 hours.

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