Preparation method and application of efficient dodecahydro-N-ethyl carbazole hydrogen release catalyst Pd-Ni / USY

Abstract

The invention discloses a preparation method and application of a dodecahydro-N-ethyl carbazole efficient hydrogen release catalyst Pd-Ni / USY, and aims to solve the problems of high noble metal content, low catalyst hydrogen release rate and the like in the preparation process of an existing supported catalyst. The preparation method comprises the following steps: 1, mixing a USY molecular sieve with a Ni (NO3) 2 aqueous solution, and carrying out ion exchange and roasting treatment; 2, NiO / USY is added into a NaBH4 aqueous solution for a reaction; 3, dispersing Ni / USY into deionized water, then adding a Pd (NO3) 2 aqueous solution, and carrying out ultrasonic-assisted electric replacement reduction reaction at room temperature; according to the present invention, with the combination of ion exchange, chemical reduction and electric replacement reduction, the ion exchange method can improve the anchoring effect of Ni, and the electric replacement reduction method can easily improve the dispersion degree of Pd and enhance the interaction between the metal active site and the USY carrier so as to improve the dehydrogenation reaction activity and the stability of the catalyst.

Description

Technical Field

[0001] The present invention belongs to the field of catalytic dehydrogenation of liquid organic hydrogen carriers, and particularly relates to a preparation method of a palladium-nickel bimetallic catalyst supported on a molecular sieve and its application in hydrogen release from liquid organic hydrogen carriers. Background Art

[0002] Due to the increasingly prominent environmental problems such as the gradual depletion of fossil resources and global warming, as well as the continuous increase in energy demand, the research on developing efficient, sustainable, and renewable energy conversion and storage materials and related technologies has received more and more extensive attention. Hydrogen energy has a high energy density and is a clean and sustainable energy carrier. When hydrogen is burned as a fuel, only water vapor and heat are produced, and no harmful gas emissions. Since hydrogen can be produced from a variety of renewable energy sources, it can reduce the dependence on fossil fuels. Therefore, hydrogen energy is an ideal energy source with application prospects and will play an important role in the future global energy structure. However, due to the low density of hydrogen, characteristics such as flammability, explosiveness, easy leakage, and a wide explosion limit, the safe, efficient, and economic storage and transportation of hydrogen have become bottlenecks restricting its large-scale application.

[0003] Common hydrogen storage methods include high-pressure gaseous hydrogen storage, cryogenic liquefied hydrogen storage, and metal hydride hydrogen storage. These hydrogen storage methods have problems such as high cost, low hydrogen storage capacity, and poor safety. Liquid organic hydrogen carrier (LOHC) hydrogen storage is one of the most promising new hydrogen storage methods, which refers to a pair of hydrogen-rich / hydrogen-poor aromatic compounds that achieve hydrogen storage and release through reversible catalytic hydrogenation and dehydrogenation reactions. LOHC hydrogen storage technology has the advantages of high hydrogen storage capacity, recyclability, clean and pollution-free, low cost, and high safety. The hydrogen carriers used have similar physical and chemical properties to petroleum-based fuel oils, and existing petroleum-based fuel storage and transportation methods and facilities can be utilized, providing a new approach for the hydrogen energy storage and transportation of hydrogen energy vehicles. However, how to achieve rapid and efficient hydrogen release of LOHC at a lower reaction temperature remains challenging.

[0004] The LOHC hydrogen storage system includes dibenzyltoluene (DBT) / octadecahydro-dibenzyltoluene (18H-DBT), toluene (TOL) / methylcyclohexane (MCH), 2-methylindole (2-MID) / octahydro-2-methylindole (8H-2-MID), N-ethylcarbazole (NEC) / dodecahydro-N-ethylcarbazole (12H-NEC), etc. Introducing heteroatoms into LOHC can reduce its hydrogenation / dehydrogenation enthalpy and reaction temperature. The mass hydrogen storage density of NEC is 5.8 wt%, and the dehydrogenation temperature of 12H-NEC is relatively low, making it an ideal LOHC. The hydrogen release (catalytic dehydrogenation) of 12H-NEC can be achieved under normal pressure and relatively mild reaction temperatures. The design and preparation of highly efficient dehydrogenation catalysts are the technical keys to improving the hydrogen storage capacity of NEC / 12H-NEC and realizing the rapid dehydrogenation of 12H-NEC.

[0005] Precious metal catalysts such as Pd and Pt are suitable catalysts for dehydrogenation reactions. Precious metal catalysts have high dehydrogenation activity, can significantly reduce the reaction temperature, and can still maintain a certain dehydrogenation activity after multiple cycles of use. They are the most promising catalysts for LOHC dehydrogenation. The supported catalyst prepared using a porous carrier can not only disperse the metal active components and expose more active sites, but the carrier may also interact with the metal active components, thereby improving the reaction activity of the catalyst. At present, the catalyst carriers used for LOHC hydrogen storage mainly include carbon carriers, aluminum oxide, mesoporous silica, and metal organic framework materials. Chinese invention patent CN 114768798 A records a palladium-based catalyst supported on partially graphitized biochar, which uses ultrasound-assisted impregnation to load Pd 2+ The Pd / C catalyst was prepared by carbon thermal reduction. When the catalyst was used for the dehydrogenation reaction of 12H-NEC, the conversion rate of 12H-NEC was 99.49% under the reaction conditions of 180°C and 6h, and the corresponding hydrogen release amount reached 5.54wt%. Patent CN 115318281 A discloses a preparation and application method of magnesium aluminum spinel and palladium-based catalyst supported thereon. The catalyst of magnesium aluminum spinel supported Pd was prepared by over-volume impregnation and sodium borohydride reduction. The catalyst was used for the dehydrogenation reaction of 12H-NEC. Under the reaction conditions of 180°C and 5h, the hydrogen release amount reached 5.63wt%. Patent CN 117399050 A records a Fe@Pd core-shell catalyst loaded on a mesoporous molecular sieve MCM-41. First, Fe is loaded on MCM-41 by electrostatic adsorption and chemical reduction, and then Pd is loaded by metal electroreplacement reaction to prepare a core-shell catalyst with Fe as the core and Pd as the shell. The catalyst is used for the dehydrogenation reaction of 12H-NEC. Under the reaction conditions of 180°C and 6h, the hydrogen release rate is as high as 100%. However, the carrier cost of these catalysts is high, the preparation process has high energy consumption, complex operation, and the use of a large amount of chemical reducing agents. The catalytic reaction process has problems such as slow hydrogen release rate and hydrogen release efficiency that still needs to be improved, making it difficult to achieve industrial application. Therefore, it is of great significance to develop a loaded high-efficiency dehydrogenation catalyst with cheap and easy-to-obtain carrier, low energy consumption, green environmental protection, and simple operation for the industrial application of LOHC. Summary of the invention

[0006] The object of the present invention is to solve the problems of high carrier cost of existing supported catalysts, use of a large amount of chemical reducing agents in the process of preparing catalysts, high noble metal content, high energy consumption, complex operation, low hydrogen release rate of catalysts, etc., and provide a method for rapidly and efficiently releasing hydrogen from dodecahydro-N-ethylcarbazole (12H-NEC) using a Pd-Ni / USY bimetallic catalyst prepared by combining ion exchange, chemical reduction and ultrasonic-assisted electroreplacement reduction method with cheap and easily available USY molecular sieve as the carrier.

[0007] The preparation method of the high-efficiency hydrogen-releasing catalyst Pd-Ni / USY for dodecahydro-N-ethylcarbazole of the present invention is realized according to the following steps:

[0008] Step 1: Preparation of NiO / USY by ion exchange of USY:

[0009] At 70-90 °C, the USY molecular sieve is fully stirred and mixed with an aqueous solution of Ni(NO3)2 for ion exchange, and then successively subjected to centrifugal separation, washing and drying, and finally calcined at a temperature of 450-650 °C to obtain NiO / USY;

[0010] Step 2: Chemical reduction of NiO / USY to prepare Ni / USY:

[0011] NiO / USY is added to an aqueous solution of NaBH4, and the reaction is stirred at room temperature under N2 protection. After centrifugal separation and washing in sequence, Ni / USY is obtained;

[0012] Step 3: Preparation of the nPd-Ni / USY catalyst:

[0013] Ni / USY is uniformly dispersed in deionized water, and then an aqueous solution of Pd(NO3)2 is added. Under N2 protection and magnetic stirring, an ultrasonic-assisted electroreplacement reduction reaction is carried out at room temperature. After the reaction ends, centrifugal separation, washing and vacuum drying are carried out in sequence to obtain the high-efficiency hydrogen-releasing Pd-Ni / USY catalyst for dodecahydro-N-ethylcarbazole.

[0014] The Pd-Ni / USY catalyst of the present invention first uses USY as the carrier, prepares NiO / USY by the ion exchange method, then prepares Ni / USY by the chemical reduction method, and then prepares Pd-Ni / USY by the ultrasonic-assisted electroreplacement reduction method.

[0015] The application of the high-efficiency hydrogen-releasing Pd-Ni / USY catalyst for dodecahydro-N-ethylcarbazole of the present invention is to use the Pd-Ni / USY catalyst for the catalytic dehydrogenation of dodecahydro-N-ethylcarbazole.

[0016] The preparation method and application of the high-efficiency hydrogen-releasing catalyst Pd-Ni / USY for dodecahydro-N-ethylcarbazole of the present invention have the following beneficial effects:

[0017] 1. The present invention provides an effective method for preparing a supported high-efficiency bimetallic catalyst with high dehydrogenation activity and low cost, which is green and environmentally friendly and has simple operation.

[0018] 2. The USY molecular sieve of the present invention is used as a carrier. Since USY not only has higher thermal stability and hydrothermal stability, but also forms intracrystalline mesopores, it can effectively "anchor" metal nanoparticles, which is beneficial to expose more active sites.

[0019] 3. Ni is introduced onto USY by an ion exchange method. 2+ The Ni / USY prepared by chemical reduction can achieve strong interaction with the carrier while reducing the Ni loading amount. On this basis, no chemical reducing agent is used during the preparation of the Pd-Ni / USY catalyst by an ultrasonic-assisted electroreplacement reduction method. It can not only achieve highly dispersed Pd on the carrier and strong interaction between Pd and Ni nanoparticles, but also realize the greening of the catalyst preparation process.

[0020] 4. The Pd-Ni / USY catalyst prepared by the present invention is used for the dehydrogenation reaction of 12H-NEC, realizing efficient and rapid hydrogen release, and the hydrogen release efficiency is significantly higher than that of the commercial Pd / AC catalyst. Description of the Drawings

[0021] Figure 1 SEM photographs of the USY molecular sieve in the examples, where Fig. (a) is magnified 5000 times and Fig. (b) is magnified 10000 times;

[0022] Figure 2 (a) N2 adsorption-desorption isotherm test chart and (b) pore size distribution curve chart of the USY molecular sieve in the examples;

[0023] Figure 3 NH3-TPD curve chart of the USY molecular sieve in the examples;

[0024] Figure 4 Infrared spectrum chart of pyridine adsorption of the USY molecular sieve in the examples;

[0025] Figure 5 HADDF-STEM photograph and its particle size distribution chart of the Pd-Ni / USY catalyst in the examples;

[0026] Figure 6 Hydrogen release curve charts of 12H-NEC catalytic dehydrogenation when using the catalysts prepared by the methods described in Examples 1, 8, and 9 respectively;

[0027] Figure 7Hydrogen release curves of dehydrogenation of 12H-NEC catalyzed by nPd-Ni / USY with different Pd loadings prepared by the methods described in Examples 1, 2, 3, and 4. Detailed implementation manners

[0028] Detailed implementation manner 1: The preparation method of the highly efficient hydrogen release catalyst Pd-Ni / USY for dodecahydro-N-ethylcarbazole is implemented according to the following steps:

[0029] Step 1: Preparation of NiO / USY by ion exchange of USY:

[0030] At 70-90 °C, the USY molecular sieve is fully stirred and mixed with an aqueous solution of Ni(NO3)2 for ion exchange, and then successively subjected to centrifugal separation, washing, and drying, and finally calcined at a temperature of 450-650 °C to obtain NiO / USY;

[0031] Step 2: Chemical reduction of NiO / USY to prepare Ni / USY:

[0032] NiO / USY is added to an aqueous solution of NaBH4, and the reaction is stirred at room temperature under N2 protection. After centrifugal separation and washing in sequence, Ni / USY is obtained;

[0033] Step 3: Preparation of the nPd-Ni / USY catalyst:

[0034] Ni / USY is uniformly dispersed in deionized water, and then an aqueous solution of Pd(NO3)2 is added. Under N2 protection and magnetic stirring, an ultrasonic-assisted electroreplacement reduction reaction is carried out at room temperature. After the reaction ends, centrifugal separation, washing, and vacuum drying are carried out in sequence to obtain the highly efficient hydrogen release Pd-Ni / USY catalyst for dodecahydro-N-ethylcarbazole.

[0035] The highly efficient hydrogen release catalyst prepared in this implementation manner is denoted as the nPd-Ni / USY catalyst, where n is the Pd loading in the catalyst, wt%.

[0036] The active components of the highly efficient hydrogen release Pd-Ni / USY catalyst in this implementation manner are Pd-Ni bimetals, and the carrier is the USY zeolite molecular sieve with intracrystalline mesopores. The preparation method is a method combining ion exchange-chemical reduction and ultrasonic-assisted electroreplacement reduction. Among them, the ion exchange method can improve the anchoring effect of USY on Ni, and the electroreplacement reduction method is beneficial to improving the dispersion of Pd, enhancing the interaction between the metal active sites and the USY carrier, thereby improving the dehydrogenation reaction activity and stability of the catalyst.

[0037] In the catalyst described in this embodiment, since USY molecular sieve is used as the carrier, metal nanoparticles can be effectively "anchored" in the intracrystalline mesopores thereof, realizing their highly dispersion and facilitating the exposure of more active sites. In the Ni / USY catalyst prepared by introducing NiO onto USY by the ion exchange method and then chemically reducing, Ni can achieve strong interaction with the molecular sieve carrier. On this basis, during the preparation of the Pd-Ni / USY catalyst by the ultrasonic-assisted electroreplacement reduction method, no chemical reducing agent is used anymore. This can not only achieve the highly dispersion of Pd on the carrier and the strong interaction between Pd and Ni nanoparticles, but also realize the greening of the catalyst preparation process, solving the problems existing in the existing catalyst preparation methods, such as high carrier cost, high energy consumption, complex operation, use of a large amount of chemical reducing agents, slow hydrogen release rate and low hydrogen release efficiency during the catalytic reaction process.

[0038] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that in Step 1, the concentration of the Ni(NO3)2 aqueous solution is 0.1 - 2.0 mol / L.

[0039] Specific Embodiment 3: The difference between this embodiment and either Specific Embodiment 1 or 2 is that in Step 1, the calcination treatment is carried out at a temperature of 500 - 600 °C for 2 - 5 h.

[0040] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that in Step 1, the ion exchange time is 0.5 - 24 h.

[0041] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that in Step 2, 1 g of NiO / USY is added to 40 mL of an aqueous NaBH4 solution with a concentration of 0.005 - 0.03 mol / L.

[0042] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that in Step 2, the reaction is stirred at room temperature for 0.2 - 2 h under N2 protection.

[0043] Specific Embodiment 7: The difference between this embodiment and any one of Specific Embodiments 1 to 6 is that in Step 3, Ni / USY is uniformly dispersed in 60 mL of deionized water, and then 1 - 10 mL of a Pd(NO3)2 aqueous solution with a concentration of 0.01 mol / L is added.

[0044] Specific Embodiment 8: The difference between this embodiment and any one of Specific Embodiments 1 to 7 is that in Step 3, the ultrasonic-assisted electroreplacement reduction reaction time is 2 - 4 h with an ultrasonic power of 200 - 400 W.

[0045] Embodiment Nine: The application of the highly efficient hydrogen-releasing Pd-Ni / USY catalyst for dodecahydro-N-ethylcarbazole is to use the Pd-Ni / USY catalyst for the catalytic dehydrogenation of dodecahydro-N-ethylcarbazole.

[0046] Embodiment Ten: The difference between this embodiment and Embodiment Ten is that dodecahydro-N-ethylcarbazole (12H-NEC) is added to an atmospheric pressure reactor, and a Pd-Ni / USY catalyst (converted to the molar percentage of Pd) accounting for 0.1 - 0.8 wt% of dodecahydro-N-ethylcarbazole (12H-NEC) is added. Stirring is carried out under the condition of a rotation speed of 300 - 800 r / min, and the reaction is carried out at 140 - 200 °C for 0.5 - 8 h under atmospheric pressure to achieve the catalytic dehydrogenation of dodecahydro-N-ethylcarbazole.

[0047] Example 1: The method for dehydrogenating 12H-NEC using a 0.4Pd-Ni / USY (the actual loading amount of Pd is 0.35 wt%) catalyst in this example is implemented according to the following steps:

[0048] The 0.4Pd-Ni / USY catalyst and 12H-NEC are mixed according to the molar percentage of Pd in the catalyst accounting for 0.3% of 12H-NEC, stirred at a rotation speed of 850 r / min, and reacted at 180 °C for 6 h to achieve the catalytic dehydrogenation of 12H-NEC.

[0049] The preparation method of the 0.4Pd-Ni / USY catalyst described in this example is as follows:

[0050] Step 1: Preparation of NiO / USY by ion exchange of USY:

[0051] At 80 °C, 5 g of USY molecular sieve is fully stirred and mixed with 150 mL of an aqueous solution of Ni(NO3)2 with a concentration of 0.5 mol / L for ion exchange for 4 h, and then successively subjected to centrifugal separation, washing, and drying (110 °C), and finally calcined at a temperature of 550 °C to obtain NiO / USY;

[0052] Step 2: Chemical reduction of NiO / USY to prepare Ni / USY:

[0053] 1 g of NiO / USY is added to 40 mL of an aqueous solution of NaBH4 with a concentration of 0.01 mol / L, and stirred and reacted at room temperature for 1 h under N2 protection, and then successively subjected to centrifugal separation and washing to obtain Ni / USY;

[0054] Step 3: Preparation of the nPd-Ni / USY catalyst:

[0055] The Ni / USY prepared in Step 2 was evenly dispersed in 60 mL of deionized water, transferred to an ultrasonic reactor, and then 3.76 mL of an aqueous Pd(NO3)2 solution with a concentration of 0.01 mol / L was added. Under N2 protection and magnetic stirring, an electroreplacement reduction reaction was carried out at a room temperature with an ultrasonic power of 300 W for 3 h. After the reaction ended, it was successively subjected to centrifugal separation, washing, and vacuum drying to obtain a 0.4Pd-Ni / USY catalyst.

[0056] The dehydrogenation of 12H-NEC was carried out using the 0.4Pd-Ni / USY catalyst prepared in Example 1, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 4.43% and 5.70% respectively, and the selectivity of NEC at 6 h of the reaction was 97.8%.

[0057] Example 2: The method for dehydrogenating 12H-NEC using a 0.3Pd-Ni / USY (the actual loading amount of Pd is 0.27 wt%) catalyst was implemented according to the following steps:

[0058] The 0.3Pd-Ni / USY catalyst was mixed with 12H-NEC such that the molar percentage of Pd in the catalyst accounted for 0.3% of 12H-NEC, stirred at a rotation speed of 850 r / min, and reacted at 180 °C for 6 h to achieve the catalytic dehydrogenation of 12H-NEC.

[0059] The preparation method of the 0.3Pd-Ni / USY catalyst described in this example is as follows:

[0060] Step 1. Preparation of NiO / USY by ion exchange of USY:

[0061] At 80 °C, 5 g of USY molecular sieve was fully stirred and mixed with 150 mL of an aqueous Ni(NO3)2 solution with a concentration of 0.5 mol / L for ion exchange for 4 h, and then successively subjected to centrifugal separation, washing, and drying (110 °C). Finally, it was calcined at a temperature of 550 °C to obtain NiO / USY;

[0062] Step 2. Chemical reduction of NiO / USY to prepare Ni / USY:

[0063] 1 g of NiO / USY was added to 40 mL of an aqueous NaBH4 solution with a concentration of 0.01 mol / L, and stirred at room temperature for 1 h under N2 protection conditions. After centrifugal separation and washing in sequence, Ni / USY was obtained;

[0064] Step 3. Preparation of the nPd-Ni / USY catalyst:

[0065] The Ni / USY prepared in Step 2 was evenly dispersed in 60 mL of deionized water, transferred to an ultrasonic reactor, and then 2.82 mL of an aqueous solution of Pd(NO3)2 with a concentration of 0.01 mol / L was added. Under N2 protection and magnetic stirring, an electroreplacement reduction reaction was carried out at a room temperature with an ultrasonic power of 300 W for 3 h. After the reaction, centrifugal separation, washing, and vacuum drying were carried out in sequence to obtain a 0.3Pd-Ni / USY catalyst.

[0066] The 0.3Pd-Ni / USY catalyst prepared in Example 2 was used for the dehydrogenation of 12H-NEC, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 4.09% and 5.65% respectively, and the selectivity of NEC at 6 h of the reaction was 97.6%.

[0067] Example 3: The method for dehydrogenating 12H-NEC using a 0.5Pd-Ni / USY (the actual loading amount of Pd is 0.50 wt%) catalyst in this example was carried out according to the following steps:

[0068] The 0.5Pd-Ni / USY catalyst and 12H-NEC were mixed according to the molar percentage of Pd in the catalyst accounting for 0.3% of 12H-NEC, stirred at a rotation speed of 850 r / min, and reacted at 180 °C for 6 h to achieve the catalytic dehydrogenation of 12H-NEC.

[0069] The difference between the preparation method of the 0.5Pd-Ni / USY catalyst described in this example and that in Example 1 is as follows:

[0070] Step 3. Preparation of the nPd-Ni / USY catalyst:

[0071] The Ni / USY prepared in Step 2 was evenly dispersed in 60 mL of deionized water, transferred to an ultrasonic reactor, and then 4.70 mL of an aqueous solution of Pd(NO3)2 with a concentration of 0.01 mol / L was added. Under N2 protection and magnetic stirring, an electroreplacement reduction reaction was carried out at a room temperature with an ultrasonic power of 300 W for 3 h. After the reaction, centrifugal separation, washing, and vacuum drying were carried out in sequence to obtain a 0.5Pd-Ni / USY catalyst.

[0072] The 0.5Pd-Ni / USY catalyst prepared in Example 3 was used for the dehydrogenation of 12H-NEC, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 3.71% and 5.50% respectively, and the selectivity of NEC at 6 h of the reaction was 94.5%.

[0073] Example 4: The method for dehydrogenating 12H-NEC using a 0.6Pd-Ni / USY (the actual loading amount of Pd is 0.51 wt%) catalyst in this example was carried out according to the following steps:

[0074] The 0.6Pd-Ni / USY catalyst was mixed with 12H-NEC such that the molar percentage of Pd in the catalyst relative to 12H-NEC was 0.3%. The mixture was stirred at 850 r / min and reacted at 180 °C for 6 h to achieve the catalytic dehydrogenation of 12H-NEC.

[0075] The preparation method of the 0.6Pd-Ni / USY catalyst described in this example is different from that in Example 1 in that:

[0076] Step 3: Preparation of the nPd-Ni / USY catalyst:

[0077] The Ni / USY prepared in Step 2 was uniformly dispersed in 60 mL of deionized water, transferred to an ultrasonic reactor, and then 5.64 mL of an aqueous solution of Pd(NO3)2 with a concentration of 0.01 mol / L was added. Under N2 protection and magnetic stirring, an electroreplacement reduction reaction was carried out at a room temperature with an ultrasonic power of 300 W for 3 h. After the reaction, centrifugal separation, washing, and vacuum drying were carried out in sequence to obtain the 0.6Pd-Ni / USY catalyst.

[0078] The 0.6Pd-Ni / USY catalyst prepared in Example 4 was used for the dehydrogenation of 12H-NEC, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 3.37% and 5.44% respectively, and the NEC selectivity at 6 h of the reaction was 92.4%.

[0079] Example 5:

[0080] The difference between this example and Example 1 is that stirring was carried out at 850 r / min and the catalytic dehydrogenation reaction was carried out at 160 °C for 6 h, and other conditions were the same as those in Example 1.

[0081] The 0.4Pd-Ni / USY catalyst prepared in Example 1 was used for the dehydrogenation of 12H-NEC, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 2.32% and 4.96% respectively, and the NEC selectivity at 6 h of the reaction was 81.7%.

[0082] Example 6:

[0083] The difference between this example and Example 1 is that stirring was carried out at 850 r / min and the catalytic dehydrogenation reaction was carried out at 170 °C for 6 h, and other conditions were the same as those in Example 1.

[0084] The 0.4Pd-Ni / USY catalyst prepared in Example 1 was used for the dehydrogenation of 12H-NEC, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 3.12% and 5.50% respectively, and the NEC selectivity at 6 h of the reaction was 93.0%.

[0085] Example 7:

[0086] The difference between this example and Example 1 is that stirring is carried out at a rotation speed of 850 r / min, and the catalytic dehydrogenation reaction is carried out at 190 °C for 6 h, and other conditions are the same as those in Example 1.

[0087] The 0.4Pd-Ni / USY catalyst prepared in Example 1 was used for dehydrogenation of 12H-NEC, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 5.33% and 5.77% respectively, and the NEC selectivity at 6 h of the reaction was 99.7%.

[0088] Example 8:

[0089] The method for dehydrogenation of 12H-NEC using a 0.4Pd / USY (the actual loading amount of Pd is 0.40 wt%) catalyst in this example is carried out according to the following steps: The 0.4Pd / USY catalyst and 12H-NEC are mixed according to the molar percentage of Pd in the catalyst accounting for 0.3% of 12H-NEC, stirred at a rotation speed of 850 r / min, and reacted at 180 °C for 6 h to achieve catalytic dehydrogenation of 12H-NEC.

[0090] The preparation method of the 0.4Pd / USY catalyst described in this example is as follows:

[0091] 1 g of USY was uniformly dispersed in 60 mL of deionized water, then transferred to an ultrasonic reactor, 3.76 mL of 0.01 mol / L Pd(NO3)2 aqueous solution was added, and under N2 protection and magnetic stirring, it was treated at a ultrasonic power of 300 W at room temperature for 3 h. After the reaction, it was centrifuged, washed with deionized water and dried in vacuum. The prepared catalyst was denoted as 0.4Pd / USY catalyst.

[0092] In this example, the Pd ions were reduced to elemental Pd by the hydroxyl radicals formed by the hydroxyl groups of the carrier under ultrasonic assistance. 2+ ions are reduced to elemental Pd.

[0093] The 0.4Pd / USY catalyst prepared in Example 8 was used for dehydrogenation of 12H-NEC, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 3.33% and 5.17% respectively, and the NEC selectivity at 6 h of the reaction was 90.5%.

[0094] Example 9:

[0095] The method for dehydrogenation of 12H-NEC using a Ni / USY catalyst in this example is carried out according to the following steps: The Ni / USY catalyst is mixed with 12H-NEC according to the catalyst dosage described in Example 1, stirred at a rotation speed of 850 r / min, and reacted at 180 °C for 6 h to achieve catalytic dehydrogenation of 12H-NEC.

[0096] The preparation method of the Ni / USY catalyst described in this example is as follows:

[0097] (1) Preparation of NiO / USY by ion exchange of USY: At 80 °C, 5 g of USY molecular sieve was fully mixed with 150 mL of 0.5 mol / L Ni(NO3)2 aqueous solution for 4 h, and then NiO / USY was obtained after centrifugal separation, washing with deionized water, drying at 110 °C, and calcining at 550 °C;

[0098] (2) Chemical reduction of NiO / USY: 40 mL of 0.01 mol / L NaBH4 aqueous solution was added to 1 g of NiO / USY, and the reaction was carried out at room temperature for 1 h under N2 protection and mechanical stirring, and then Ni / USY was obtained after centrifugal separation, washing with deionized water, and vacuum drying;

[0099] The Ni / USY catalyst prepared in Example 9 was used for dehydrogenation of 12H-NEC, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 0.04% and 0.08% respectively, and the NEC selectivity at 6 h of the reaction was 32.4%.

[0100] Example 10:

[0101] The method for dehydrogenation of 12H-NEC using a commercial Pd / AC (AC represents activated carbon) catalyst (5 wt% Pd) in this example was carried out according to the following steps: The Pd / AC catalyst and 12H-NEC were mixed according to the molar percentage of Pd in the catalyst accounting for 0.3% of 12H-NEC, stirred at a rotation speed of 850 r / min, and reacted at 180 °C for 6 h to achieve catalytic dehydrogenation of 12H-NEC.

[0102] The Pd / AC catalyst described in Example 10 was used for dehydrogenation of 12H-NEC, and the reaction results are shown in Table 1. The hydrogen release amounts at 1 h and 6 h of the reaction were 3.43% and 5.18% respectively, and the NEC selectivity at 6 h of the reaction was 90.9%.

[0103] Table 1 shows the dehydrogenation reaction results of 12H-NEC using different catalysts.

[0104] Table 1 Dehydrogenation reaction results of 12H-NEC using different catalysts

[0105]

Claims

1. A method for preparing a highly efficient hydrogen release catalyst Pd-Ni / USY of dodecahydro-N-ethylcarbazole, characterized in that The preparation method of the hydrogen release catalyst Pd-Ni / USY is achieved by the following steps: Step 1: Preparation of NiO / USY by ion exchange of USY: At 70-90°C, USY molecular sieve and Ni(NO3)2 aqueous solution are fully stirred and mixed for ion exchange, then centrifuged, washed and dried in sequence, and finally calcined at 450-650°C to obtain NiO / USY; Step 2: Chemical reduction of NiO / USY to prepare Ni / USY: NiO / USY is added into NaBH4 aqueous solution, stirred at room temperature under N2 protection, and then centrifuged and washed to obtain Ni / USY; Step 3: Preparation of nPd-Ni / USY catalyst: Ni / USY was uniformly dispersed in deionized water, and then Pd(NO3)2 aqueous solution was added. Ultrasonic-assisted electro-replacement reduction reaction was carried out at room temperature under N2 protection and magnetic stirring. After the reaction, centrifugal separation, washing and vacuum drying were performed in sequence to obtain Pd-Ni / USY catalyst for efficient hydrogen release of dodecahydro-N-ethylcarbazole.

2. The method for preparing the dodecahydro-N-ethylcarbazole efficient hydrogen release catalyst Pd-Ni / USY according to claim 1, characterized in that The concentration of the Ni(NO3)2 aqueous solution in step 1 is 0.1-2.0 mol / L.

3. The method for preparing the dodecahydro-N-ethylcarbazole efficient hydrogen release catalyst Pd-Ni / USY according to claim 1, characterized in that In step 1, the calcination treatment time is 2 to 5 hours at a temperature of 500 to 600°C.

4. The method for preparing the dodecahydro-N-ethylcarbazole efficient hydrogen release catalyst Pd-Ni / USY according to claim 1, characterized in that The ion exchange time in step 1 is 0.5 to 24 hours.

5. The method for preparing the dodecahydro-N-ethylcarbazole efficient hydrogen release catalyst Pd-Ni / USY according to claim 1, characterized in that In step 2, 1 g of NiO / USY is added to 40 mL of a 0.005-0.03 mol / L NaBH4 aqueous solution.

6. The method for preparing the dodecahydro-N-ethylcarbazole efficient hydrogen release catalyst Pd-Ni / USY according to claim 1, characterized in that In step 2, the reaction is stirred at room temperature under N2 protection for 0.2 to 2 h.

7. The method for preparing the dodecahydro-N-ethylcarbazole efficient hydrogen release catalyst Pd-Ni / USY according to claim 1, characterized in that In step 3, Ni / USY is uniformly dispersed in 60 mL of deionized water, and then 1 to 10 mL of a 0.01 mol / L Pd(NO3)2 aqueous solution is added.

8. The method for preparing the dodecahydro-N-ethylcarbazole efficient hydrogen release catalyst Pd-Ni / USY according to claim 1, characterized in that In step 3, the ultrasonic-assisted electro-reduction reaction time is 2 to 4 hours with an ultrasonic power of 200 to 400 W.

9. Use of the dodecahydro-N-ethylcarbazole efficient hydrogen release catalyst Pd-Ni / USY prepared as claimed in claim 1, characterized in that The high-efficiency hydrogen-releasing catalyst Pd-Ni / USY is used for the catalytic dehydrogenation of dodecahydro-N-ethylcarbazole.

10. Use of the dodecahydro-N-ethylcarbazole efficient hydrogen release catalyst Pd-Ni / USY according to claim 9, characterized in that Add dodecahydro-N-ethylcarbazole into a normal pressure reactor, add a Pd-Ni / USY catalyst accounting for 0.1 to 0.8 wt% of dodecahydro-N-ethylcarbazole, stir at a rotation speed of 300 to 800 r / min, and react at 140 to 200°C under normal pressure for 0.5 to 8 hours to achieve catalytic dehydrogenation of dodecahydro-N-ethylcarbazole.

Images