Preparation method and application of nitrogen-doped carbon nanotube modified Beta zeolite loaded PdNi bimetallic catalyst of dodecahydro-N-ethyl carbazole

Abstract

The invention discloses a preparation method and application of a nitrogen-doped carbon nanotube modified Beta zeolite loaded PdNi bimetallic catalyst of dodecahydro-N-ethyl carbazole, and aims to solve the problems of high dehydrogenation temperature, low rate and the like in the application of 12H-NEC catalytic dehydrogenation. The preparation method comprises the following steps: 1, adding Beta zeolite into a nickel salt aqueous solution, dipping to obtain a Ni / Beta catalyst, mixing melamine and the Ni / Beta catalyst, putting the mixture into a tubular furnace, and carrying out a carbon thermal reduction reaction at the temperature of 500-900 DEG C in an N2 atmosphere; and 2, adding the Ni / Beta-NCNT into a solution of a palladium precursor, and carrying out an electric replacement reduction reaction. The introduction of the NCNT improves the electron transport capacity, defect sites formed on the surface of the CNT after N doping promote dispersion of Pd nanoparticles, and the synergistic effect of the two effectively improves the catalytic performance of the Pd nanoparticles in the dehydrogenation reaction of dodecahydro-N-ethyl carbazole.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of palladium-nickel bimetallic catalysts, and particularly relates to a preparation method and application of a dodecahydro-N-ethylcarbazole nitrogen-doped carbon nanotube-modified Beta zeolite-loaded PdNi bimetallic catalyst. Background Art

[0002] Hydrogen energy is a secondary energy source with many advantages, including high combustion heat release, abundant sources, and environmental friendliness. However, hydrogen storage is a bottleneck in its utilization. Liquid organic hydrogen carriers (LOHCs) utilize the reversible hydrogenation and dehydrogenation of liquid organic matter to achieve hydrogen storage and release. LOHC hydrogen storage can utilize existing oil and gas facilities to achieve long-distance hydrogen transportation, solving the problems of high-pressure hydrogen storage and natural gas pipeline transportation. It is one of the most promising low-cost hydrogen storage and transportation technologies. N-ethylcarbazole (NEC) belongs to the LOHC containing N heterocycles. It has a mass hydrogen storage capacity of 5.8wt.% and a complete dehydrogenation temperature below 200°C, making it a relatively ideal LOHC. In order to realize the commercial application of LOHC containing N heterocycles, the development of dehydrogenation catalysts with high catalytic activity, high selectivity, low cost and good catalytic stability is the key to the commercial application of LOHC containing N heterocycles.

[0003] Supported noble metal catalysts exhibit high catalytic activity for the dehydrogenation of N-heterocyclic LOHCs, with Pd exhibiting the best catalytic performance. Currently reported Pd catalysts still face challenges in commercial applications of 12H-NEC dehydrogenation, including high dehydrogenation temperatures and slow rates. Bimetallic catalysts prepared by selecting suitable supports and incorporating non-noble metals can not only enhance catalytic activity but also reduce catalyst costs, offering promising commercial application prospects. Summary of the Invention

[0004] In order to solve the problems of high dehydrogenation temperature and slow rate faced in the commercial application of 12H-NEC catalytic dehydrogenation, the present invention provides a preparation method and application of a nitrogen-doped carbon nanotube-modified Beta zeolite-supported PdNi bimetallic catalyst for 12H-NEC dehydrogenation.

[0005] The preparation method of the present invention of the dodecahydro-N-ethylcarbazole nitrogen-doped carbon nanotube-modified Beta zeolite supported PdNi bimetallic catalyst is achieved by the following steps:

[0006] Step 1: Preparation of Nitrogen-doped Carbon Nanotube-Modified Beta Zeolite-Supported Nickel Catalyst (Ni / Beta-NCNT):

[0007] a. Adding Beta zeolite to a nickel salt aqueous solution to obtain a Ni / Beta catalyst (Beta zeolite-supported nickel catalyst) by wet impregnation;

[0008] b. Melamine and Ni / Beta catalyst were mixed and placed in a tube furnace, and subjected to carbothermal reduction reaction at a temperature of 500-900° C. under a nitrogen atmosphere to obtain a Ni / Beta-NCNT catalyst (a catalyst containing nickel supported on Beta zeolite modified with nitrogen-doped carbon nanotubes);

[0009] Step 2: Preparation of Beta-NCNT-loaded PdNi bimetallic catalyst (PdNi / Beta-NCNT):

[0010] Ni / Beta-NCNT was added to a palladium precursor solution for electrochemical reduction reaction. After washing and drying, a nitrogen-doped carbon nanotube-modified Beta zeolite-loaded PdNi bimetallic catalyst for 12H-NEC dehydrogenation was obtained.

[0011] The application of the nitrogen-doped carbon nanotube-modified Beta zeolite-supported PdNi bimetallic catalyst for dodecahydro-N-ethylcarbazole of the present invention is to put the nitrogen-doped carbon nanotube-modified Beta zeolite-supported PdNi bimetallic catalyst for 12H-NEC dehydrogenation and dodecahydro-N-ethylcarbazole into a reactor and carry out a dehydrogenation reaction at a temperature of 120-200°C.

[0012] The preparation method and application of the dodecahydro-N-ethylcarbazole nitrogen-doped carbon nanotube-modified Beta zeolite-supported PdNi bimetallic catalyst of the present invention include the following beneficial effects:

[0013] 1. The preparation method of the nitrogen-doped carbon nanotube-modified Beta zeolite-supported PdNi bimetallic catalyst for 12H-NEC dehydrogenation of the present invention comprises: first, using a wet impregnation method to support Ni on Beta zeolite to prepare Ni / Beta; then, using melamine as a carbon source, in situ growing nitrogen-doped carbon nanotubes (NCNTs) on the surface of Ni / Beta to prepare NCNT-modified Ni / Beta-NCNT. Subsequently, the catalyst is wet-impregnated with palladium salt and then subjected to galvanic reduction to obtain a nitrogen-doped carbon nanotube-modified Beta zeolite-supported PdNi bimetallic catalyst (PdNi / Beta-NCNT). The catalyst preparation process is simple to operate and has low preparation cost.

[0014] 2. The composite support prepared by introducing NCNT into Beta molecular sieve can effectively improve the electron transport capacity. The defect sites formed on the surface of N-doped CNT can promote the dispersion of Pd nanoparticles. The synergistic effect of the two can effectively increase the dehydrogenation rate of the PdNi / Beta-NCNT catalyst in the 12H-NEC dehydrogenation reaction and reduce the dehydrogenation temperature. When the dehydrogenation reaction temperature is 180°C and the reaction time is 2h, the hydrogen release rate of 12H-NEC reaches as high as 100%, providing possibilities for the commercial application of LOHC containing N heterocycles.

[0015] 3. The introduction of Ni into the Beta-NCNT composite carrier-loaded PdNi bimetallic catalyst can not only modulate the electronic structure of the precious metal Pd and improve the catalytic activity of Pd, but also reduce the cost of Pd-based catalysts, meeting the commercial application needs of Pd-based catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 TEM image of PdNi / Beta-NCNT bimetallic catalyst A for 12H-NEC dehydrogenation in Example 1;

[0017] Figure 2 The XPS spectrum of Pd 3d of PdNi / Beta-NCNT bimetallic catalyst A used for 12H-NEC dehydrogenation in Example 1;

[0018] Figure 3 The XPS spectrum of Ni 2p of PdNi / Beta-NCNT bimetallic catalyst A for 12H-NEC dehydrogenation in Example 1;

[0019] Figure 4 The C1s XPS spectrum of the PdNi / Beta-NCNT bimetallic catalyst A used for 12H-NEC dehydrogenation in Example 1;

[0020] Figure 5 The Raman spectra of PdNi / Beta-NCNT bimetallic catalysts A, B, and C used for 12H-NEC dehydrogenation in Examples 1, 2, and 3 are shown;

[0021] Figure 6 The Raman spectra of PdNi / Beta-NCNT bimetallic catalysts A, F, G, H, and I used for 12H-NEC dehydrogenation in Examples 1, 6, 7, 8, and 9 are shown;

[0022] Figure 7 12H-NEC hydrogen release curves when the PdNi / Beta-NCNT bimetallic catalyst A in Example 1 and the commercial Pd / C in Comparative Example 1 were used as catalysts;

[0023] Figure 8 The hydrogen release curves of 12H-NEC when PdNi / Beta-NCNT bimetallic catalysts A, D, and E are used as catalysts in Examples 1, 4, and 5;

[0024] Figure 9 12H-NEC hydrogen release curves when PdNi / Beta-NCNT bimetallic catalysts A, J, and K are used as catalysts in Examples 1, 10, and 11;

[0025] Figure 101 is a hydrogen release curve when the molar percentages of PdNi / Beta-NCNT bimetallic A and 12H-NEC are 0.2, 0.3, and 0.4%, respectively;

[0026] Figure 11 12H-NEC hydrogen release curves when the PdNi / Beta-NCNT bimetallic catalyst A is used in Example 13 and the reaction temperatures are 150, 160, 170, and 180°C, respectively;

[0027] Figure 12 This is a bar chart of the experimental results of the 12H-NEC dehydrogenation reaction cycle when the PdNi / Beta-NCNT bimetallic catalyst A is used in Example 1. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below with reference to the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the scope of the technical solution of the present invention shall be included in the scope of protection of the present invention. The process equipment or devices not specifically noted in the following examples are all conventional equipment or devices in the art. Unless otherwise specified, the raw materials used in the examples of the present invention can be obtained commercially; unless otherwise specified, the technical means used in the examples of the present invention are all conventional means well known to those skilled in the art.

[0029] Specific embodiment 1: The preparation method of the PdNi bimetallic catalyst supported on Beta zeolite modified by nitrogen-doped carbon nanotubes of dodecahydro-N-ethylcarbazole in this embodiment is carried out according to the following steps:

[0030] Step 1: Preparation of Nitrogen-doped Carbon Nanotube-Modified Beta Zeolite-Supported Nickel Catalyst (Ni / Beta-NCNT):

[0031] a. Adding Beta zeolite to a nickel salt aqueous solution to obtain a Ni / Beta catalyst (Beta zeolite-supported nickel catalyst) by wet impregnation;

[0032] b. Melamine and Ni / Beta catalyst were mixed and placed in a tube furnace, and subjected to carbothermal reduction reaction at a temperature of 500-900° C. under a nitrogen atmosphere to obtain a Ni / Beta-NCNT catalyst (a catalyst containing nickel supported on Beta zeolite modified with nitrogen-doped carbon nanotubes);

[0033] Step 2: Preparation of Beta-NCNT-loaded PdNi bimetallic catalyst (PdNi / Beta-NCNT):

[0034] Ni / Beta-NCNT was added to the palladium precursor solution to undergo an electrochemical reduction reaction (Ni to Pd 2+The PdNi bimetallic catalyst supported on Beta zeolite modified with nitrogen-doped carbon nanotubes for 12H-NEC dehydrogenation was obtained after washing and drying.

[0035] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the nickel salt described in step a is nickel chloride (NiCl2), nickel sulfate (NiSO4), nickel nitrate (Ni(NO3)2) or nickel nitrite (Ni(NO2)2), and the concentration of the nickel salt aqueous solution is 0.01~1mol / L.

[0036] Specific embodiment three: This embodiment differs from specific embodiment one or two in that the liquid-to-solid ratio (mass ratio) of the nickel salt aqueous solution to Beta in step a is 1 to 20:1.

[0037] Specific embodiment 4: This embodiment differs from any one of specific embodiments 1 to 3 in that the mass ratio of melamine to Ni / Beta catalyst in step b is 15 to 50:1.

[0038] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the carbon thermal reduction reaction time in step b is 1 to 4 hours.

[0039] Specific embodiment six: The difference between this embodiment and any one of specific embodiments one to five is that the palladium precursor described in step two is sodium chloropalladate (Na2PdCl4), chloropalladic acid (H2PdCl4), dichlorotetraamminepalladium (Pd(NH3)4Cl2) or palladium nitrate (Pd(NO3)2), and the solution concentration of the palladium precursor is 0.01~0.1mol / L.

[0040] Specific embodiment seven: This embodiment differs from any one of specific embodiments one to six in that the liquid-to-solid ratio (mass ratio) of the palladium precursor solution and the Beta-NCNT-supported PdNi bimetallic catalyst in step two is 1 to 50:1.

[0041] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that the time for the electro-replacement reduction reaction in step two is 1 to 10 hours.

[0042] Specific embodiment nine: In this embodiment, the application of the nitrogen-doped carbon nanotube-modified Beta zeolite-loaded PdNi bimetallic catalyst of dodecahydro-N-ethylcarbazole is to put the nitrogen-doped carbon nanotube-modified Beta zeolite-loaded PdNi bimetallic catalyst for 12H-NEC dehydrogenation and dodecahydro-N-ethylcarbazole into a reactor and carry out the dehydrogenation reaction at a temperature of 120 to 200°C.

[0043] Specific embodiment ten: This embodiment differs from specific embodiment nine in that the amount of nitrogen-doped carbon nanotube-modified Beta zeolite-supported PdNi bimetallic catalyst used for 12H-NEC dehydrogenation (converted to Pd) accounts for 0.1 to 1.0% by mole of dodecahydro-N-ethylcarbazole.

[0044] Specific embodiment eleven: This embodiment differs from specific embodiment nine in that the dehydrogenation reaction time is 1 to 8 hours.

[0045] Example 1: The preparation method of the PdNi bimetallic catalyst supported on Beta zeolite modified with nitrogen-doped carbon nanotubes of dodecahydro-N-ethylcarbazole in this example is carried out according to the following steps:

[0046] Step 1: Preparation of Nitrogen-doped Carbon Nanotube-Modified Beta Zeolite-Supported Nickel Catalyst (Ni / Beta-NCNT):

[0047] a. Add 1 g of Beta zeolite to 3.4 g of a 1 mol / L NiCl2 aqueous solution at a solid-liquid ratio of 1:3.4 (mass ratio), wet-impregnate for 12 h, and then dry to obtain a Ni / Beta catalyst (Beta zeolite-supported nickel catalyst);

[0048] b. 2 g of melamine and 0.1 g of Ni / Beta catalyst were mixed and placed in a tube furnace. The mixture was heated to 800° C. at a heating rate of 5° C. / min under a nitrogen atmosphere for a carbothermal reduction reaction for 2.5 h to obtain a Ni / Beta-NCNT catalyst (a nitrogen-doped carbon nanotube-modified Beta zeolite-supported nickel catalyst).

[0049] Step 2: Preparation of Beta-NCNT-loaded PdNi bimetallic catalyst (PdNi / Beta-NCNT):

[0050] 1 g of Ni / Beta-NCNT was added to 9.4 g of 0.01 mol / L Na2PdCl4 solution for electrochemical reduction reaction for 3 h. After centrifugation, washing and drying, a nitrogen-doped carbon nanotube-modified Beta zeolite-loaded PdNi bimetallic catalyst for 12H-NEC dehydrogenation was obtained, which was recorded as catalyst A.

[0051] Step 3: PdNi / Beta-NCNT catalyst is used for dehydrogenation of dodecahydro-N-ethylcarbazole:

[0052] Catalyst A and 12H-NEC were mixed such that the molar percentage of Pd in ​​the catalyst was 0.3% of the 12H-NEC. The mixture was stirred at 20 rpm and reacted at 180°C. The reaction results are shown in Table 1. The hydrogen released after 1 h and 2 h of reaction was 5.38 wt.% and 5.80 wt.%, respectively.

[0053] Example 2:

[0054] Different from Example 1, in step 1 of this example, the temperature was raised to 900° C. under N 2 atmosphere and maintained for 2.5 h. Other conditions were the same as in Example 1. The prepared PdNi / Beta-NCNT was recorded as catalyst B.

[0055] Catalyst B and 12H-NEC catalyst were reacted under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 4 h of reaction was 5.15 wt.% and 5.80 wt.%, respectively.

[0056] Example 3:

[0057] Different from Example 1, in step 1 of this example, the temperature was raised to 700° C. under N 2 atmosphere and maintained for 2.5 h. Other conditions were the same as those in Example 1. The prepared PdNi / Beta-NCNT was designated as catalyst C.

[0058] Catalyst C and 12H-NEC catalyst were reacted under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 6 h of reaction were 4.44 wt.% and 5.78 wt.%, respectively.

[0059] Example 4:

[0060] Different from Example 1, in step 1 of this example, the temperature was raised to 800° C. under N 2 atmosphere and maintained for 3 h. Other conditions were the same as in Example 1. The prepared PdNi / Beta-NCNT was recorded as catalyst D.

[0061] Catalyst D and 12H-NEC catalyst were reacted under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 4 h of reaction were 4.97 wt.% and 5.80 wt.%, respectively.

[0062] Example 5:

[0063] Different from Example 1, in step 1 of this example, the temperature was raised to 800° C. under N 2 atmosphere and maintained for 2 h. Other conditions were the same as in Example 1. The prepared PdNi / Beta-NCNT was recorded as catalyst E.

[0064] Catalyst E and 12H-NEC catalyst were reacted under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 6 h of reaction was 4.64 wt.% and 5.80 wt.%, respectively.

[0065] Example 6:

[0066] The difference from Example 1 is that the liquid-to-solid ratio (mass ratio) of the NiCl2 aqueous solution to the Beta zeolite in step 1 of this embodiment is 1.7:1. Other conditions are the same as those in Example 1. The prepared PdNi / Beta-NCNT is recorded as catalyst F.

[0067] Catalyst F and 12H-NEC catalyst were reacted under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 4 h of reaction were 4.96 wt.% and 5.80 wt.%, respectively.

[0068] Example 7:

[0069] The difference from Example 1 is that the liquid-to-solid ratio (mass ratio) of the NiCl2 aqueous solution to the Beta zeolite in step 1 of this embodiment is 5.1:1. Other conditions are the same as those in Example 1. The prepared PdNi / Beta-NCNT is recorded as catalyst G.

[0070] Catalyst G and 12H-NEC catalyst were reacted under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 3 h of reaction were 5.03 wt.% and 5.80 wt.%, respectively.

[0071] Example 8:

[0072] The difference from Example 1 is that the liquid-to-solid ratio (mass ratio) of the NiCl2 aqueous solution to the Beta zeolite in step 1 of this embodiment is 6.8:1. Other conditions are the same as those in Example 1. The prepared PdNi / Beta-NCNT is recorded as catalyst H.

[0073] Catalyst H and 12H-NEC catalyst were reacted under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 4 h of reaction were 4.81 wt.% and 5.80 wt.%, respectively.

[0074] Example 9:

[0075] The difference from Example 1 is that the liquid-to-solid ratio (mass ratio) of the NiCl2 aqueous solution to the Beta zeolite in step 1 of this embodiment is 8.5:1. Other conditions are the same as those in Example 1. The prepared PdNi / Beta-NCNT is recorded as catalyst I.

[0076] Catalyst I was reacted with 12H-NEC catalyst under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 6 h of reaction was 4.94 wt.% and 5.80 wt.%, respectively.

[0077] Example 10:

[0078] Different from Example 1, in this embodiment, the liquid-solid ratio (mass ratio) of the NiCl2 aqueous solution to the Beta zeolite in step 1 is 3.4:1, and the liquid-solid ratio (mass ratio) of the Na2PdCl4 solution to the Ni / Beta-NCNT in step 2 is 28.2:1. The other conditions are the same as in Example 1. The prepared PdNi / Beta-NCNT is recorded as catalyst J.

[0079] Catalyst J was reacted with 12H-NEC catalyst under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 6 h of reaction was 4.03 wt.% and 5.67 wt.%, respectively.

[0080] Example 11:

[0081] Different from Example 1, in this embodiment, the liquid-solid ratio (mass ratio) of the NiCl2 aqueous solution to the Beta zeolite in step 1 is 3.4:1, and the liquid-solid ratio (mass ratio) of the Na2PdCl4 solution to the Ni / Beta-NCNT in step 2 is 4.7:1. The other conditions are the same as in Example 1, and the prepared PdNi / Beta-NCNT is recorded as catalyst K.

[0082] Catalyst K and 12H-NEC catalyst were reacted under the conditions of step 3 in Example 1. The reaction results are shown in Table 1. The hydrogen released after 1 h and 4 h of reaction were 4.76 wt.% and 5.80 wt.%, respectively.

[0083] Example 12:

[0084] Different from Example 1, in step 3 of this embodiment, catalyst A and 12H-NEC were mixed so that the molar percentage of Pd in ​​the catalyst to 12H-NEC was 0.2% and 0.4%, respectively. The reaction results are shown in Table 1.

[0085] Example 13:

[0086] Different from Example 1, in step 3 of this embodiment, catalyst A reacted with 12H-NEC catalyst at 150, 160, and 170° C., respectively. The reaction results are shown in Table 1.

[0087] Comparative Example 1:

[0088] A commercial Pd / C catalyst with a Pd loading of 5 wt.% was used as the dehydrogenation catalyst to catalyze the dehydrogenation of 12H-NEC at 180°C. The reaction results are shown in Table 1. The hydrogen released after 1 h and 6 h was 3.23 wt.% and 5.59 wt.%, respectively.

[0089] Table 1 12H-NEC dehydrogenation reaction results using different catalysts

[0090]

[0091]

Claims

1. A method for preparing a PdNi bimetallic catalyst supported on Beta zeolite modified with nitrogen-doped carbon nanotubes of dodecahydro-N-ethylcarbazole, characterized in that The preparation method is achieved by following the steps: Step 1: Preparation of Nitrogen-doped Carbon Nanotube-Modified Beta Zeolite-Loaded Nickel Catalyst: a. Adding Beta zeolite to a nickel salt aqueous solution to obtain a Ni / Beta catalyst by wet impregnation; b. Mixing melamine and Ni / Beta catalyst and placing them in a tube furnace, and performing a carbothermal reduction reaction at a temperature of 500-900° C. under a nitrogen atmosphere to obtain a Ni / Beta-NCNT catalyst; Step 2: Preparation of Beta-NCNT-loaded PdNi bimetallic catalyst: Ni / Beta-NCNT was added to a palladium precursor solution for electrochemical reduction reaction. After washing and drying, a nitrogen-doped carbon nanotube-modified Beta zeolite-loaded PdNi bimetallic catalyst for 12H-NEC dehydrogenation was obtained.

2. The method for preparing the PdNi bimetallic catalyst supported on Beta zeolite modified by nitrogen-doped carbon nanotubes of dodecahydro-N-ethylcarbazole according to claim 1, characterized in that The nickel salt described in step a is nickel chloride, nickel sulfate, nickel nitrate or nickel nitrite, and the concentration of the nickel salt aqueous solution is 0.01-1 mol / L.

3. The method for preparing the PdNi bimetallic catalyst supported on Beta zeolite modified by nitrogen-doped carbon nanotubes of dodecahydro-N-ethylcarbazole according to claim 1, characterized in that In step b, the mass ratio of melamine to Ni / Beta catalyst is 15 to 50:

1.

4. The method for preparing the PdNi bimetallic catalyst supported on Beta zeolite modified by nitrogen-doped carbon nanotubes of dodecahydro-N-ethylcarbazole according to claim 1, characterized in that The carbon thermal reduction reaction time in step b is 1 to 4 hours.

5. The method for preparing the PdNi bimetallic catalyst supported on Beta zeolite modified by nitrogen-doped carbon nanotubes of dodecahydro-N-ethylcarbazole according to claim 1, characterized in that The palladium precursor in step 2 is sodium chloropalladate, chloropalladic acid, dichlorotetraamminepalladium or palladium nitrate, and the concentration of the palladium precursor solution is 0.01-0.1 mol / L.

6. The method for preparing the PdNi bimetallic catalyst supported on Beta zeolite modified by nitrogen-doped carbon nanotubes of dodecahydro-N-ethylcarbazole according to claim 1, characterized in that In step 2, the liquid-solid mass ratio of the palladium precursor solution and the Beta-NCNT-loaded PdNi bimetallic catalyst is 1 to 50:

1.

7. The method for preparing the PdNi bimetallic catalyst supported on Beta zeolite modified by nitrogen-doped carbon nanotubes of dodecahydro-N-ethylcarbazole according to claim 1, characterized in that The time of the electrochemical reduction reaction in step 2 is 1 to 10 hours.

8. Use of the nitrogen-doped carbon nanotube-modified Beta zeolite supported on PdNi bimetallic catalyst prepared as claimed in claim 1, characterized in that Beta zeolite loaded with PdNi bimetallic catalyst and dodecahydro-N-ethylcarbazole modified with nitrogen-doped carbon nanotubes for 12H-NEC dehydrogenation are put into a reactor, and dehydrogenation reaction is carried out at a temperature of 120-200°C.

9. Use of the dodecahydro-N-ethylcarbazole nitrogen-doped carbon nanotube-modified Beta zeolite supported on a PdNi bimetallic catalyst according to claim 8, characterized in that The amount of the nitrogen-doped carbon nanotube-modified Beta zeolite-supported PdNi bimetallic catalyst used for 12H-NEC dehydrogenation is 0.1-1.0% of the mole percentage of dodecahydro-N-ethylcarbazole.

10. Use of the dodecahydro-N-ethylcarbazole nitrogen-doped carbon nanotube-modified Beta zeolite supported PdNi bimetallic catalyst according to claim 8, characterized in that The dehydrogenation reaction time is 1 to 8 hours.

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