Metal oxide-anchored nanometal catalysts enriched with oxygen vacancies, methods of making and using the same

Abstract

The application discloses a catalyst, in which active metal nanoparticles are anchored on metal oxides containing oxygen vacancies. The application also discloses a preparation method of the catalyst and an application of the catalyst in catalytic dehydrogenation of naphthenes. The catalyst has stable and efficient dehydrogenation activity in catalytic dehydrogenation of naphthenes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalysts, and particularly relates to a metal oxide-anchored nanometal catalyst rich in oxygen vacancies, a preparation method thereof and application thereof. BACKGROUND

[0002] The temperature of the fuselage (outer surface) and fuel tank rises sharply when the aircraft flies at a high Mach number. In the case of a Mach number of 8, the temperature of the uncooled scramjet combustor structure will exceed 2700℃, far exceeding the high-temperature bearing limit of known materials, which indicates that the system needs to be cooled with fuel. Endothermic hydrocarbon fuels meet the requirements of regenerative cooling while exhibiting good combustion and endothermic capacity. Physical and chemical endothermic processes occur on the surface of high-temperature components before the fuel flows into the combustor. At present, most research focuses on improving the chemical heat sink of hydrocarbon fuels. The chemical reactions of hydrocarbon fuels mainly used for endothermic include cracking reactions and dehydrogenation reactions. Among them, stable and efficient naphthenic dehydrogenation reactions can provide a higher heat sink.

[0003] Partial dehydrogenation (PDH) of liquid fuels has recently been proposed as a technology for hydrogen delivery, which is based on the principle of producing hydrogen from endothermic hydrocarbon fuels for fuel cell applications, while the endothermic hydrocarbon fuel after dehydrogenation still maintains good fuel properties. Modern hydrogen storage technology relies on the reversibility and high selectivity of liquid organic hydrogen carriers (LOHCs), among which methylcyclohexane and decalin have a very high hydrogen storage density. The dehydrogenation reaction of organic hydrogen carriers naphthenes occurs at a relatively low reaction temperature (200-500℃) and reaction pressure (0-3MPa) and low weight hourly space velocity (WHSV <100h -1 ).

[0004] Active metal catalysts are widely used in the dehydrogenation of naphthenes in industry. However, the common active metals often face the problem of easy sintering at high temperature. Al2O3 is widely used as a dehydrogenation catalyst support due to its thermal stability and high specific surface area. In recent years, reducible metal oxides (such as TiO2) are used as catalyst supports to regulate the anti-sintering performance and catalytic performance of active metals. High-temperature hydrogen reduction treatment can produce oxygen vacancies at the interface between the active metal and the support. Since transition metal cations have vacant d orbitals, they can receive residual electrons from oxygen anions; this causes the orbital bonding between the active metal and the transition metal cations with increased electron density, resulting in the transfer of electrons in the support to the active metal; and strong ionic bonds are generated between the negatively charged active metal and the positively charged cations on the surface of the support, which makes the active metal have better catalytic dehydrogenation stability and activity. However, the poor thermal stability and limited specific surface area limit the application of reducible metal oxides under some harsh conditions. Therefore, improving the thermal stability of the catalyst structure and enhancing the active metal-support interaction are contradictory, and the problems of easy sintering of active metals and low catalytic dehydrogenation activity under high reaction temperature and high space velocity conditions need to be solved

[0005] The present application is proposed to solve the above problems. SUMMARY

[0006] The present application is proposed to solve the above problems, and a metal oxide with more oxygen vacancies is anchored to a nanometer metal catalyst. The catalyst of the present application introduces alkaline earth metal ions into TiO2-Al2O3 metal oxides to increase the content of oxygen vacancies in the metal oxides and anchor the active metal at the oxygen vacancies, with the particle size of the active metal controlled at 1-20 nm; at the same time, the electronic density of the active metal is also increased, and its catalytic dehydrogenation activity is improved. In the dehydrogenation reactions of naphthenes such as decalin, methylcyclohexane, cyclohexane, perhydrodibenzyltoluene, dodecahydro-N-ethylcarbazole, and tetrahydrocarbazole, the active metal exhibits excellent catalytic naphthene dehydrogenation stability and activity at high temperature and high space velocity. The orbital bonding between the active metal and the transition metal cations with increased electronic density causes the electrons of the reduced metal cations in the support to transfer to the active metal, resulting in strong ionic bonds between the negatively charged active metal and the positively charged cations on the surface of the support, which improves the anti-sintering performance of the active metal at high temperature. The catalyst and the preparation method thereof have high potential application value.

[0007] The metal oxide anchored nanometal catalyst rich in oxygen vacancies of the present application creates more oxygen vacancies on the surface of the metal oxide, so that the active metal particles are anchored at the oxygen vacancies of the metal oxide, which promotes the bonding of the active metal with the outermost orbital of the reducible metal cation, so that the active metal has electron-rich characteristics and high catalytic efficiency. Moreover, the active metal nanoparticles and the metal oxide have strong interaction and good high-temperature stability.

[0008] The technical solution of the present application is as follows:

[0009] The first aspect of the present application discloses a catalyst, wherein the active metal nanoparticles are anchored on the metal oxide containing oxygen vacancies.

[0010] Preferably, the active metal is one or more of Pt, Rh, Pd, Fe, Ni, Cr and Cu, and the content of the active metal is 0.01-20.0wt% of the total amount of the active metal and the metal oxide containing oxygen vacancies; the particle size of the active metal nanoparticles is 1-20nm.

[0011] Preferably, the metal oxide containing oxygen vacancies is an alkaline earth metal modified TiO2-Al2O3 metal oxide, wherein the content of the oxide of the alkaline earth metal in the total amount of the metal oxide containing oxygen vacancies is 1-30wt%.

[0012] The second aspect of the present application discloses a preparation method of the catalyst, comprising the following steps:

[0013] (1) preparing a metal oxide solution containing oxygen vacancies;

[0014] (2) adding an alkaline solution dropwise to the solution prepared in step (1);

[0015] (3) mixing the mixed solution prepared in step (2) at 25-80℃ for 1-5 hours and aging for 1-5 hours to obtain a mixed sol;

[0016] (4) washing the mixed sol obtained in step (3) with deionized water until neutral, and then drying to obtain a solid;

[0017] (5) calcining the solid prepared in step (4) in an air atmosphere at 300-700℃ for 1-10 hours to obtain a powdery solid;

[0018] (6) dissolving the powdery solid prepared in step (5) in deionized water to prepare a solution;

[0019] (7) mixing the solution prepared in step (6) with an active metal precursor solution, and mixing at 25-80℃ for 1-24 hours to obtain a dispersion;

[0020] (8) separating and drying the dispersion of step (7) to obtain a solid powder;

[0021] (9) calcining the solid powder obtained in step (8) in air at 300-600°C for 1-5 hours to obtain;

[0022] (10) reducing the calcined solid powder of step (9) in a hydrogen atmosphere at 300-600°C for 1-5 hours to obtain the catalyst.

[0023] Preferably, in step (1), the metal oxide containing oxygen vacancies is an Al 3+ ion precursor, a T i 4+ ion precursor and an alkaline earth metal ion-containing precursor; the Al 3+ ion precursor is one of Al (NO3) 3 ·9H2O, Al (NO3) 3, AlCl3 ·6H2O, AlCl3, Al2 (SO4) 3 ·xH2O, Al2 (SO4) 3 ; the T 4+ ion precursor is one of TiOSO4 ·xH2SO4 ·yH2O, TiOSO4, Ti[OCH (CH3) 2]4, TiOSO4 · (H2SO4) x , TiCl3, TiCl4, TiCl4 ·2THF; the alkaline earth metal ion-containing precursor is one of MgSO4, MgSO4 ·7H2O, MgSO4 ·1H2O, Mg (NO3) 2 ·6H2O, MgCl2, MgCl2 ·6H2O, CaSO4, CaSO4 ·0.5H2O, CaSO4 ·2H2O, Ca (NO3) 2 ·4H2O, CaCl2, CaCl2 ·xH2O, Sr (NO3) 2, SrCl2, SrCl2 ·6H2O, BaSO4, Ba (NO3) 2, BaCl2, BaCl2 ·2H2O, Ba (ClO4) 2 ; the solvent is water and / or ethanol.

[0024] Preferably, in step (2), the alkaline solution is one of ammonium carbonate solution or ammonia water; the molar ratio of the components in the mixed solution is: Al 3+ ion precursor: T 4+ ion precursor: alkaline earth metal ion precursor: base in alkaline solution = (0.01-1) : (0.01-1) : (0.01-1) : (0.01-1).

[0025] Preferably, the active metal precursor solution in step (7) is one or more of H2PtCl6, Pt(NH3)2(NO2)2, Rh(acac)3, RhCl3.3H2O, Pd(NO2)(NH3)2, PdSO4, Pd(NO3)2, PdCl2, Fe2(SO4)3.xH2O FeSO4.xH2O, (NH4)2Fe(SO4)2.6H2O, Fe(NO3)3.9H2O, FeCl3, FeCl2, NiSO4.7H2O, NiSO4.6H2O, (NH4)2Ni(SO4)2.6H2O, Ni(NO3)2.6H2O, Ni(OH)2, NiCl2, Cr2(SO4)3.xH2O, Cr(NO3)3.9H2O, CrCl2, Cr(CO)6, CuSO4, Cu(NH3)4SO4.H2O, Cu(NO3)2.3H2O, CuCl2.2H2O, CuCl2 solution.

[0026] The third aspect of the present application discloses the use of the catalyst for catalytic dehydrogenation of naphthenes.

[0027] Preferably, the catalyst is mixed with quartz sand after being prepared into particles; the mass space velocity of the catalytic dehydrogenation reaction is 0.5-2000h-1; the reaction temperature is 300-750 DEG C; and the reaction pressure is 0.1-4 MPa. -1

[0028] The beneficial effects of the present application are as follows:

[0029] 1. The preparation method of the metal oxide anchored nanometal catalyst rich in oxygen vacancies, wherein the TiO2-Al2O3 metal oxide modified by an alkaline earth metal is synthesized by a coprecipitation method, the active metal is uniformly loaded on the surface of the metal oxide by an impregnation method and a calcination method, and more oxygen vacancies are generated at the interface between the active metal and the metal oxide by a high-temperature hydrogen reduction treatment method to anchor the active metal.

[0030] 2. The preparation method of the metal oxide anchored nanometal catalyst rich in oxygen vacancies, wherein the content of oxygen vacancies in the TiO2-Al2O3 metal oxide is increased by introducing alkaline earth metal ions, the bonding between the active metal and the outermost orbital of the reducible metal cation is promoted, the electron transfer effect between the active metal and the carrier is enhanced, the active metal has electron-rich characteristics, the interaction force between the active metal and the metal oxide is enhanced, and the high-temperature stability is good.

[0031] ​3. The metal oxide anchored nanometal catalyst rich in oxygen vacancies of the present application, on the basis of ensuring good thermal stability of the metal oxide, enhances the electron transfer effect between the active metal and the metal oxide and increases the electron density of the active metal, and is used for catalytic dehydrogenation of naphthenes such as decalin, methylcyclohexane, cyclohexane, perhydrodibenzyltoluene, dodecahydro-N-ethylcarbazole and tetrahydrocarbazole, etc., to improve the catalytic dehydrogenation activity thereof.

[0032] 4. The metal oxide anchored nanometal catalyst rich in oxygen vacancies of the present application is used for catalytic dehydrogenation of naphthenes, and has stable and efficient catalytic dehydrogenation activity of naphthenes under high temperature (300-750℃) and high space velocity (e.g. WHSV = 2058.7h -1 ) conditions.

[0033] 5. The metal oxide anchored nanometal catalyst rich in oxygen vacancies of the present application is used for catalytic dehydrogenation of naphthenes, and the amount of alkaline earth metal is not the more the better. Among all the alkaline earth metals, magnesium modified TiO2-Al2O3 metal oxide has a better effect, and the content of MgO in Al2O3-TiO2-MgO oxide is about 10wt%. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a low temperature EPR graph of the catalyst obtained in Example 1-4.

[0035] Figure 2 is a low temperature CO-FTIR graph of the catalyst obtained in Example 1-4.

[0036] Figure 3 is a dehydrogenation effect graph of decalin at a space velocity (WHSV = 514.7h -1 ) in Example 1-4 catalysis.

[0037] Figure 4 is a dehydrogenation effect graph of decalin at a space velocity (WHSV = 1029.3h -1 ) in Example 3 catalysis.

[0038] Figure 5 is a dehydrogenation effect graph of decalin at a space velocity (WHSV = 2058.7h -1 ) in Example 3 catalysis.

[0039] Figure 6 is a dehydrogenation effect graph of decalin at a space velocity (WHSV = 514.7h -1 ) in Example 8 catalysis. DETAILED DESCRIPTION

[0040] The application will be further described in detail by specific examples, which can make the skilled in the art more fully understand the application, but not in any way limit the application.

[0041] In the preparation of the catalyst of the application, the Al-containing 3+ ion precursor is one of Al (NO3) 3·9H2O, Al (NO3) 3, AlCl3·6H2O, AlCl3, Al2 (SO4) 3·xH2O, Al2 (SO4) 3; the Ti-containing 4+ ion precursor is one of TiOSO4·xH2SO4·yH2O, TiOSO4, Ti[OCH (CH3) 2]4, TiOSO4· (H2SO4) x , TiCl3, TiCl4, TiCl4·2THF; the alkaline earth metal ion precursor is one of MgSO4, MgSO4·7H2O, MgSO4·1H2O, Mg (NO3) 2·6H2O, MgCl2, MgCl2·6H2O, CaSO4, CaSO4·0.5H2O, CaSO4·2H2O, Ca (NO3) 2·4H2O, CaCl2, CaCl2·xH2O, Sr (NO3) 2, SrCl2, SrCl2·6H2O, BaSO4, Ba (NO3) 2, BaCl2, BaCl2·2H2O, Ba (ClO4) 2. The alkaline solution is one of ammonium carbonate solution or ammonia water, the active metal precursor solution is one or several of H2PtCl6, Pt (NH3) 2 (NO2) 2, Rh (acac) 3, RhCl3·3H2O, Pd (NO2) (NH3) 2, PdSO4, Pd (NO3) 2, PdCl2, Fe2 (SO4) 3·xH2O FeSO4·xH2O, (NH4) 2Fe (SO4) 2·6H2O, Fe (NO3) 3·9H2O, FeCl3, FeCl2, NiSO4·7H2O, NiSO4·6H2O, (NH4) 2Ni (SO4) 2·6H2O, Ni (NO3) 2·6H2O, Ni (OH) 2, NiCl2, Cr2 (SO4) 3·xH2O, Cr (NO3) 3·9H2O, CrCl2, Cr (CO) 6, CuSO4, Cu (NH3) 4SO4·H2O, Cu (NO3) 2·3H2O, CuCl2·2H2O, CuCl2 solution. The water used is deionized water, the ethanol used is pure ethanol. The reagents used are all analytical reagents.

[0042] The low temperature ESR / EPR test of the obtained finished product was determined by A300 paramagnetic resonance spectrometer of Bruker Company, the CO in-situ infrared test of the obtained finished product was determined by iS50 FT-IR Fourier infrared spectrometer of NICOLET Company, and the metal content of the obtained finished product was determined by element analyzer Agilent 725ES&Agilent 5110(OES) of the United States.

[0043] Examples 1-4

[0044] 15.3 g of aluminum nitrate nonahydrate, 1.8 g of titanyl sulfate-sulfuric acid hydrate and a proper amount of anhydrous magnesium sulfate were dissolved in 200 mL of deionized water and continuously stirred at 50°C for 30 minutes to prepare a carrier precursor mixed solution. 10 g of ammonium carbonate was dissolved in 100 mL of deionized water to prepare an ammonium carbonate solution, which was then added dropwise to the carrier precursor mixed solution and continuously stirred at 50°C for 3 hours, and then aged at room temperature for 2 hours to obtain a mixed sol; then the obtained mixed sol was separated by suction filtration and washed with deionized water until neutral, and dried at 80°C for 12 hours. The obtained block solid was ground into powder, which was calcined in an air atmosphere at 600°C for 5 hours to obtain a solid powder.

[0045] 2 g of the obtained solid powder after calcination and 0.12 g of chloroplatinic acid were dissolved in 200 mL of aqueous solution, wherein the mass fraction of Pt in the solid powder was 2.8 wt%, and continuously stirred at 50°C for 12 hours to obtain a dispersion. Then the solid powder was separated by vacuum rotary evaporation drying, and dried at 80°C for 12 hours to obtain a solid powder; the obtained solid powder was calcined in an air atmosphere at 400°C for 3 hours; then the obtained solid powder was reduced in a hydrogen atmosphere at 500°C for 5 hours to obtain a metal oxide anchored nanometal catalyst rich in oxygen vacancy.

[0046] The mass of the anhydrous magnesium sulfate used in Example 1 was 0 g (marked as Pt / TA); the mass of the anhydrous magnesium sulfate used in Example 2 was 0.45 g (the content of MgO in the Al2O3-TiO2-MgO oxide was 5 wt%, marked as Pt / MTA-5); the mass of the anhydrous magnesium sulfate used in Example 3 was 1.0 g (the content of MgO in the Al2O3-TiO2-MgO oxide was 10 wt%, marked as Pt / MTA-10); the mass of the anhydrous magnesium sulfate used in Example 4 was 2.2 g (the content of MgO in the Al2O3-TiO2-MgO oxide was 20 wt%, marked as Pt / MTA-20).

[0047] The low temperature EPR chart of the catalyst prepared in Examples 1-4 is as follows:Figure 1 As shown. By Figure 1 It can be seen that with the increase of MgO doping amount, the content of oxygen vacancies on the catalyst surface increases significantly.

[0048] The CO-FTIR spectra of the catalysts prepared in Examples 1-4 are as follows: Figure 2 As shown. By Figure 2 It can be seen that doping MgO into the Pt / TiO2-Al2O3 catalyst support leads to a significant red shift in the CO adsorption peak, indicating that MgO doping can increase the electron density of Pt.

[0049] Example 5

[0050] The catalysts from Examples 1-4 were used for the direct dehydrogenation reaction of decahydronaphthalene at high space velocity. The specific steps included: pressing the catalyst into tablets and crushing it into granules of 20-40 mesh size; uniformly mixing the granular catalyst with quartz sand to a total volume of 1.5 g, then loading it into the isothermal section of a fixed-bed reactor; introducing nitrogen gas and adjusting the reaction system pressure through a back pressure valve, shutting off the nitrogen gas when the pressure reached 4 MPa; then heating the reactor to 600°C; subsequently introducing decahydronaphthalene at a mass hourly space velocity (HHSV) of 514.7 h⁻¹. -1 .

[0051] The effects of Examples 1-4 are as follows Figure 3 As shown. By Figure 3 It can be seen that the catalyst (Pt / MTA-10) obtained in Example 3 has high dehydrogenation activity and stability. Within 300 minutes, the conversion rate remains above 56%, and the selectivity for naphthalene in the liquid phase product remains above 60%.

[0052] The Pt / TiO2-Al2O3 catalyst without MgO doping in Example 1 exhibited a high initial conversion rate, which gradually decreased over time (see...). Figure 3 (a)); The Pt / TiO2-Al2O3 catalyst without MgO doping also exhibits high selectivity, which gradually decreases with increasing time (see...). Figure 3 (b) ; It cannot maintain long-term stability.

[0053] Example 6

[0054] The catalyst from Example 3 was used to catalyze the direct dehydrogenation reaction of decahydronaphthalene at high space velocity. The specific steps included: pressing the catalyst into tablets and crushing it into granules of 20-40 mesh size. The granular catalyst was then uniformly mixed with quartz sand to a total volume of 1.5 g, and then loaded into the isothermal section of a fixed-bed reactor. Nitrogen gas was then introduced, and the pressure of the reaction system was adjusted using a back pressure valve. When the pressure reached 4 MPa, the nitrogen gas was shut off. The reactor was then heated to 600°C. Decahydronaphthalene was then introduced at a mass hourly space velocity (HHSV) of 1029.3 h⁻¹.-1 .

[0055] The effect of Example 3 is as follows Figure 4 As shown. By Figure 4 It can be seen that the catalyst (Pt / MTA-10) obtained in Example 3 has a mass hourly space velocity (H₂S) of 1029.3 h⁻¹. -1 It also exhibits high dehydrogenation activity and stability, maintaining a conversion rate of over 50% within 240 minutes, and a selectivity for naphthalene in the liquid phase product of over 49%.

[0056] Example 7

[0057] The catalyst from Example 3 was used to catalyze the direct dehydrogenation reaction of decahydronaphthalene at high space velocity. The specific steps included: pressing the catalyst into tablets and crushing it into granules of 20-40 mesh size. The granular catalyst was then uniformly mixed with quartz sand to a total volume of 1.5 g, and then loaded into the isothermal section of a fixed-bed reactor. Nitrogen gas was then introduced, and the pressure of the reaction system was adjusted using a back pressure valve. When the pressure reached 4 MPa, the nitrogen gas was shut off. The reactor was then heated to 600°C. Decahydronaphthalene was then introduced at a mass hourly space velocity (HHSV) of 2058.7 h⁻¹. -1 .

[0058] The effect of Example 3 is as follows Figure 5 As shown. By Figure 5 It can be seen that the catalyst (Pt / MTA-10) obtained in Example 3 has a mass hourly space velocity (H₂S) of 2058.7 h⁻¹. -1 It also exhibits high dehydrogenation activity and stability, maintaining a conversion rate of over 48% within 120 minutes, and a selectivity for naphthalene in the liquid phase product of over 39%.

[0059] Example 8

[0060] Weigh 15.3 g of aluminum nitrate nonahydrate, 2.8 g of titanium tetraisopropoxide, and 0.8 g of calcium sulfate tetrahydrate and add them to 100 mL of ethanol solution. Then add 100 mL of deionized water to the precursor solution and stir continuously at 50 °C for 30 minutes to prepare a carrier precursor mixed solution. Add ammonia solution dropwise to the carrier precursor mixed solution until the pH of the solution is 9, and stir continuously at 50 °C for 3 hours. Then let it stand at room temperature for 2 hours to obtain a mixed sol. Then filter the obtained mixed sol, wash it with deionized water until neutral, and dry it at 80 °C for 12 hours. Grind the obtained block solid into powder and calcine it in air at 600 °C for 5 hours to obtain a solid powder.

[0061] 2g of the calcined solid powder and 0.12g of chloroplatinic acid were dissolved in 200ml of aqueous solution, wherein the mass fraction of Pt in the solid powder was 2.8wt%, and the mixture was continuously stirred at 50℃ for 12 hours to obtain a dispersion. The solid powder was then separated by vacuum rotary evaporation and dried at 80℃ for 12 hours to obtain a solid powder. The obtained solid powder was calcined in air at 400℃ for 3 hours. Then, the obtained solid powder was reduced in hydrogen atmosphere at 500℃ for 5 hours to obtain an oxygen-vacancy-rich metal oxide-anchored nano-metal catalyst (CaO content in Al2O3-TiO2-CaO oxide was 5wt%, labeled as Pt / CTA-5).

[0062] The catalyst from Example 8 was used to catalyze the direct dehydrogenation reaction of decahydronaphthalene at high space velocity. The specific steps included: pressing the catalyst into tablets and crushing it into granules of 20-40 mesh size; uniformly mixing the granular catalyst with quartz sand to a total volume of 1.5 g, then loading it into the isothermal section of a fixed-bed reactor; introducing nitrogen gas and adjusting the reaction system pressure through a back pressure valve, shutting off the nitrogen gas when the pressure reached 4 MPa; then heating the reactor to 600°C; subsequently introducing decahydronaphthalene at a mass hourly space velocity (HHSV) of 514.7 h⁻¹. -1 .

[0063] The effect of Example 8 is as follows Figure 6 As shown. By Figure 6 It can be seen that the catalyst (Pt / CTA-5) obtained in Example 8 has a mass hourly space velocity (HHSV) of 514.7 h⁻¹. -1 It also exhibits high dehydrogenation activity and stability, maintaining a conversion rate of over 50% within 120 minutes, and a selectivity for naphthalene in the liquid phase product of over 44%.

[0064] Example 9

[0065] The catalyst from Example 3 was used to catalyze the direct dehydrogenation of cyclohexane at high space velocity (HSV). The specific steps included: pressing the catalyst into tablets and crushing it into granules of 20-40 mesh size. The granular catalyst was then uniformly mixed with quartz sand to a total volume of 1.5 g, and then loaded into the isothermal section of a fixed-bed reactor. Nitrogen gas was then introduced, and the reaction system pressure was adjusted using a back pressure valve. When the pressure reached 4 MPa, the nitrogen gas was shut off. The reactor was then heated to 600 °C. Decahydronaphthalene was then introduced at a mass hourly space velocity (HHSV) of 514.7 h⁻¹. -1 .

[0066] Example 3 yielded a catalyst (Pt / MTA-10) with a mass hourly space velocity (H₂Sv) of 514.7 h⁻¹. -1 It also exhibits high dehydrogenation activity and stability, maintaining a conversion rate of over 60% within 300 minutes, and a selectivity for benzene in the liquid phase product of over 70%.

[0067] Example 10

[0068] The catalyst of Example 3 was used to catalyze the direct dehydrogenation of perhydrodibenzyltoluene at high space velocity. Specifically, the following steps were included: the catalyst was pressed into tablets and crushed to a granular size of 20-40 mesh. The granular catalyst was uniformly mixed with quartz sand to a total amount of 1.5 g, and then packed into the constant temperature section of a fixed bed reactor. Nitrogen was then introduced, and the pressure of the reaction system was adjusted by a back pressure valve. When the pressure reached 4 MPa, the nitrogen was turned off. The reactor was then heated to 600°C. Perhydrodibenzyltoluene was then introduced, with a mass space velocity of 514.7 h -1 .

[0069] The catalyst (Pt / MTA-10) obtained in Example 3 also had high dehydrogenation activity and stability at a mass space velocity of 514.7 h -1 , with the conversion rate remaining above 60% and the selectivity of p-dibenzyltoluene in the liquid phase product remaining above 70% within 300 min.

[0070] Example 11

[0071] The catalyst of Example 3 was used to catalyze the direct dehydrogenation of dodecahydro-N-ethylcarbazole at high space velocity. Specifically, the following steps were included: the catalyst was pressed into tablets and crushed to a granular size of 20-40 mesh. The granular catalyst was uniformly mixed with quartz sand to a total amount of 1.5 g, and then packed into the constant temperature section of a fixed bed reactor. Nitrogen was then introduced, and the pressure of the reaction system was adjusted by a back pressure valve. When the pressure reached 4 MPa, the nitrogen was turned off. The reactor was then heated to 600°C. Dodecahydro-N-ethylcarbazole was then introduced, with a mass space velocity of 514.7 h -1 .

[0072] The catalyst (Pt / MTA-10) obtained in Example 3 also had high dehydrogenation activity and stability at a mass space velocity of 514.7 h -1 , with the conversion rate remaining above 60% and the selectivity of p-dibenzyltoluene in the liquid phase product remaining above 70% within 300 min.

[0073] Example 12

[0074] The catalyst of Example 3 was used to catalyze the direct dehydrogenation of dodecahydro-N-ethylcarbazole at high space velocity. Specifically, the following steps were included: the catalyst was pressed into tablets and crushed to a granular size of 20-40 mesh. The granular catalyst was uniformly mixed with quartz sand to a total amount of 1.5 g, and then packed into the constant temperature section of a fixed bed reactor. Nitrogen was then introduced, and the pressure of the reaction system was adjusted by a back pressure valve. When the pressure reached 4 MPa, the nitrogen was turned off. The reactor was then heated to 600°C. Dodecahydro-N-ethylcarbazole was then introduced, with a mass space velocity of 514.7 h -1 .

[0075] Example 3 obtained catalyst (Pt / MTA-10) at mass space velocity of 514.7h -1 The catalyst also has higher dehydrogenation activity and stability, and the conversion rate is maintained above 70% within 300 min, and the selectivity of the liquid phase product to carbazole is maintained above 80%.

[0076] The above examples only express the embodiments of the present application, which are described in more detail and in more detail, but cannot be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. Use of a catalyst for catalytic dehydrogenation of naphthenes, characterized in that, The mass space velocity of the catalytic dehydrogenation reaction is 514.7-2000 h -1 , the reaction temperature is 600 DEG C, the reaction pressure is 4 MPa; the cycloalkane is one of decalin, methylcyclohexane, cyclohexane, perhydrodibenzyltoluene, dodecahydro-N-ethylcarbazole or tetrahydrocarbazole; the catalyst is active metal nanoparticles anchored on an oxygen vacancy-containing metal oxide; the active metal is Pt; the oxygen vacancy-containing metal oxide is an alkaline earth metal modified TiO2-Al2O3 metal oxide, the alkaline earth metal is Mg, and the content of MgO in the Al2O3-TiO2-MgO oxide is 10 wt%. The preparation method of the catalyst comprises the following steps: (1) preparing an oxygen-vacancy-containing metal oxide precursor solution; the oxygen-vacancy-containing metal oxide precursor is an Al-containing 3+ ion precursor, a T i 4+ ion precursor, and an alkali earth metal ion-containing precursor; (2) dropping the alkaline solution into the solution prepared in step (1); (3) mixing the mixed solution prepared in step (2) at 25-80℃ for 1-5 hours and aging for 1-5 hours to obtain a mixed sol; (4) washing the mixed sol obtained in step (3) with deionized water until neutral and drying to obtain a solid; (5) calcining the solid prepared in step (4) in air at 300-700℃ for 1-10 hours to obtain a powder solid; (6) dissolving the powder solid prepared in step (5) in deionized water to obtain a solution; (7) mixing the solution prepared in step (6) with an active metal precursor solution and mixing at 25-80℃ for 1-24 hours to obtain a dispersion; (8) separating and drying the dispersion prepared in step (7) to obtain a solid powder; (9) calcining the solid powder prepared in step (8) in air at 300-600℃ for 1-5 hours to obtain a solid powder; (10) reducing the calcined solid powder prepared in step (9) in a hydrogen atmosphere at 300-600℃ for 1-5 hours to obtain the catalyst.

2. Use according to claim 1, characterized in that, The content of the active metal is 0.01-20.0 wt% of the active metal in the total amount of the active metal and the metal oxide containing oxygen vacancies; and the particle size of the active metal nanoparticles is 1-20 nm.

3. Use according to claim 1, characterized in that, In step (1), the Al-containing 3+ The ionic precursor is one of Al(NO3)3.9H2O, Al(NO3)3, AlCl3.6H2O, AlCl3, Al2(SO4)3.xH2O, Al2(SO4)3; the Ti-containing 4+ The ionic precursor is one of TiOSO4.xH2SO4.yH2O, Ti[OCH(CH3)2]4, TiCl3, TiCl4, TiCl4.2THF; the alkaline earth metal ion-containing precursor is one of MgSO4, MgSO4.7H2O, MgSO4.H2O, Mg(NO3)2.6H2O, MgCl2, MgCl2.6H2O; and the solvent is water and / or ethanol.

4. Use according to claim 1, characterized in that, In step (2), the alkaline solution is one of ammonium carbonate solution or ammonia water.

5. The use according to claim 1, characterized in that, The active metal precursor solution in step (7) is one or both of H2PtCl6 or Pt(NH3)2(NO2)2 solution.

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