Catalyst and method for the preparation of gamma-valerolactone by dehydrogenation of 1,4-pentanediol

Abstract

The application relates to a preparation method of a catalyst for catalyzing 1,4-pentanediol dehydrogenation to prepare gamma-valerolactone and application of the catalyst, and the catalyst is Cu / PrO x -ZnO. Soluble salts of copper salt, zinc salt and praseodymium salt are dissolved in a mixed solution of deionized water and an organic solvent and ultrasonically dissolved; then, a complexing agent and a structure directing agent are sequentially added, ultrasonically dissolved again, and then transferred to a 100ml high-pressure hydrothermal kettle, and aged at 90-180 DEG C for 6-72h, and then washed, dried and calcined after cooling to obtain a nanosheet-shaped Cu / PrO x -ZnO catalyst. By using the catalyst, 1,4-pentanediol is efficiently catalytically converted to prepare gamma-valerolactone under a solvent-free condition in a trickle bed reactor at 160-210 DEG C, the conversion rate of 1,4-pentanediol is greater than 99%, the selectivity of gamma-valerolactone is greater than 97%, the catalyst has good stability, and the catalytic activity is not obviously reduced after continuous operation for 200h. The catalyst has a hierarchical multi-level pore nanosheet structure, rich basic sites and defect sites, good active metal dispersion, high activity, easy recovery, high stability and high product yield.

Description

Technical Field

[0001] The present invention relates to the fields of chemical energy technology and advanced chemical raw materials, and in particular to a catalyst and a preparation method for preparing gamma-valerolactone by dehydrogenating 1,4-pentanediol. Background Art

[0002] γ-Valerolactone (GVL) is a colorless or pale yellow liquid with a vanillin and coconut aroma. It has a high boiling point, strong solubility, is miscible with water and ethanol, and is stable and safe to use. It is an excellent solvent widely used in the preparation of liquid fuels. It can also be used as an additive for gasoline, diesel, and biodiesel. When mixed with gasoline, its antiknock properties are similar to those of ethanol. Research results show that the properties of a gasoline blend (95# gasoline) obtained by adding 10% GVL to 90% gasoline are very similar to those of a gasoline blend with the same volume of ethanol, with a similar octane number. Because GVL does not form an azeotrope with water, its lower vapor pressure improves the fuel's combustion performance. Furthermore, GVL is an important raw material for fine chemicals and organic chemicals, primarily used in the synthesis of other carbon-based chemicals and polymers.

[0003] In recent years, with the continuous expansion of the use of GVL, its market demand has increased significantly. Existing GVL production is synthesized by hydrogenation of levulinic acid or levulinic ester. However, levulinic acid is an organic acid with strong acidity in the aqueous phase, which places high demands on reaction instruments and equipment. In addition, commonly used hydrogenation catalysts often contain precious metal components. These factors have led to higher GVL production costs. Recently, there have also been reports of using furfural as raw material to prepare GVL through a one-pot process through multiple reactions such as catalytic hydrogenation, hydrolysis and hydrogenolysis. However, this process has many side reactions, complex product distribution, and low yield of the target product. Therefore, there is an urgent need to develop a new approach to prepare GVL with green process, simple operation and high efficiency.

[0004] 1,4-Pentanediol is an important energy chemical and basic organic chemical raw material. Catalytic dehydrogenation of 1,4-pentanediol to GVL has potential industrial applications due to its environmentally friendly, simple process, low cost, minimal side reactions, and high product yield. However, few reports have been published.

[0005] Reaction formula for preparing GVL by dehydrogenation of 1,4-pentanediol

[0006] On December 20, 2024, a search was conducted in the Chinese Patent Publication Database using "γ-valerolactone and Cu and PrO and ZnO and dehydrogenation and catalyst" as abstract keywords, with the option of allowing synonym expansion checked, but no relevant literature was found.

[0007] On December 20, 2024, an abstract search for "γ-valerolactone and Cu and PrO and ZnO and dehydrogenation and catalyst" was conducted on China National Knowledge Infrastructure, and no relevant literature was found.

[0008] On December 20, 2024, a search for "Gamma valerolactone with Cu with PrO with ZnO with dehydrogenation with catalyst" was conducted on the website of the United States Patent and Trademark Office, but no relevant literature was found; the search URL is https: / / ppubs.uspto.gov / pubwebapp / .

[0009] On December 20, 2024, a search was conducted on the Korean Intellectual Property Office for "Gamma valerolactone and Cu and PrO and ZnO and dehydrogenation and catalyst", but no relevant literature was found; the search URL was http: / / eng.kipris.or.kr / enghome / main.jsp.

[0010] On December 20, 2024, a search was conducted on WIPO's https: / / patentscope2.wipo.int / for "Gamma valerolactone and Cu and PrO and ZnO anddehydrogenation and catalyst", and no relevant literature was found.

[0011] On December 20, 2024, a search for "Gamma valerolactone and Cu and PrO and ZnO and dehydrogenation and catalyst" was conducted on the Japan Patent Office website https: / / www.j-platpat.inpit.go.jp / , but no relevant literature was found.

[0012] It is completely different from the conception of this patent. Summary of the Invention

[0013] Purpose of the invention: To provide a more effective catalyst and preparation method for dehydrogenating 1,4-pentanediol to prepare γ-valerolactone. The specific purpose can be seen in the multiple substantial technical effects in the specific implementation part.

[0014] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0015] A catalyst for preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol, characterized in that the catalyst is Cu / PrO x -ZnO; wherein the mass ratio of Cu:Pr:Zn is m(Cu):m(Pr):m(Zn):=(0.07~0.52):(0.04~0.34):1.

[0016] A method for preparing a catalyst for dehydrogenating 1,4-pentanediol to prepare γ-valerolactone, characterized by comprising the following steps:

[0017] Dissolve copper salt, zinc salt and praseodymium salt in a mixed solution of deionized water and an organic solvent to prepare a metal salt mixed solution, and dissolve it by ultrasonication; wherein the mass ratio of Cu:Pr:Zn is m(Cu):m(Pr):m(Zn):=(0.07-0.52):(0.04-0.34):1;

[0018] After uniform dissolution, add the complexing agent and structure directing agent in sequence, and then ultrasonically dissolve for 0.5h~1h. After complete dissolution, stir in a water bath at 60℃~80℃ for 0.5h~1h to obtain a uniformly mixed suspension;

[0019] The mixed suspension was then transferred to a 100 ml high pressure hydrothermal autoclave and aged at 90°C to 180°C for 6h to 72h.

[0020] After cooling, the precipitate is washed 3 to 5 times with deionized water and ethanol by centrifugation, dried in a drying oven at 80 to 150° C. for 8 to 16 hours, and then calcined in a muffle furnace at 300 to 700° C. for 3 to 5 hours to obtain a composite metal oxide catalyst.

[0021] A further technical solution of the present invention is that the copper salt, zinc salt and praseodymium salt are selected from any one or more soluble salts of copper salt, zinc salt and praseodymium salt respectively; the organic solvent is any one of N,N-dimethylformamide DMF and ethanol; the complexing agent is triethanolamine, and the structure directing agent is a gemini surfactant which is 2-undecyl(heptadeca)-1-formamidoethylimidazolinehexanediamine quaternary ammonium salt.

[0022] A further technical solution of the present invention is that, in the metal salt mixture, the mass concentration of Cu is 1.50 g / L to 7.50 g / L, the mass concentration of Zn is 14.44 g / L to 21.60 g / L, and the mass concentration of Pr is 0.96 g / L to 4.87 g / L;

[0023] In the mixed solution of deionized water and organic solvent, the volume ratio of deionized water to organic solvent is 0.2:1 to 1:1.

[0024] The added amount of the complexing agent is 10g to 30g based on the mass of triethanolamine added to 1L of the metal salt mixture; the added amount of the structure directing agent is 4g to 16g based on the mass of gemini surfactant added to 1L of the metal salt mixture.

[0025] A further technical solution of the present invention is to introduce a 2-undecyl (heptadecanyl)-1-formamidoethyl imidazoline hexanediamine quaternary ammonium salt gemini surfactant as a structure-directing agent during the catalyst preparation process to control the pore structure in the catalyst. In addition, the imidazoline gemini surfactant has a unique molecular structure similar to a "triblock" polymer. The strong chemical adsorption and bonding of nitrogen and oxygen atoms in the structure to metal ions can inhibit or promote the growth of certain crystal faces, thereby effectively controlling the catalyst morphology.

[0026] During the catalyst preparation process, a weak base complexing agent triethanolamine TEA was introduced. Based on the property that triethanolamine can be evenly hydrolyzed to release OH under hydrothermal conditions, Cu 2+ , Zn 2+ and Pr 3+ The ions are evenly complexed to form [M(OH)4] 2- Precursor and {[M(OH)4]2-TEA} ligand, M refers to Cu 2+ 、Zn 2+ 、Pr 3+；

[0027] During the hydrothermal-calcination process, the catalyst is thermally decomposed into a layered multi-level porous nanosheet composite metal oxide; the catalyst has highly dispersed active Cu sites, abundant basic sites and Pr 3+ -O v -Pr 3+ Defective structures and favorable Cu-O-Pr and Cu-O-Zn interface sites; the unique synergistic effects between surface metal sites, basic sites, defective structures, and Cu-O-Zn and Cu-O-Pr interfaces contribute to the improved efficiency of the dehydrogenation of 1,4-pentanediol to γ-valerolactone. Triblock polymers are composed of three distinct polymer segments, each with unique chemical and physical properties. This structural design allows for high tunability and optimization of triblock polymer properties. By adjusting the length, chemical composition, and sequence of each segment, precise control of material properties can be achieved to meet diverse application requirements.

[0028] A further technical solution of the present invention is that the catalyst has a specific surface area of ​​120m 2 / g~180m 2 / g, showing a multi-level pore distribution, in which pores smaller than 2nm account for 2% to 10%, pores of 2nm to 15nm account for 67% to 90%, and the rest are macropores with a diameter of 15-30nm.

[0029] A further technical solution of the present invention is that the catalyst can generate highly dispersed active Cu sites, abundant basic sites and Pr 3+ -O v -Pr 3+ Defect structure and favorable Cu-O-Zn and Cu-O-Pr interface sites; under the unique synergistic effect between surface metal sites, basic sites, defect structure and Cu-O-Zn and Cu-O-Pr interfaces, the efficiency of 1,4-pentanediol dehydrogenation to γ-valerolactone can be significantly improved.

[0030] A method for synthesizing γ-valerolactone, characterized in that, under solvent-free conditions, 1,4-pentanediol is dehydrogenated to prepare γ-valerolactone using a catalyst in a trickle bed reactor; the catalyst is Cu / PrO x -ZnO; wherein the mass ratio of Cu:Pr:Zn is m(Cu):m(Pr):m(Zn):=(0.07-0.52):(0.04-0.34):1;

[0031] The catalyst is reduced in situ in a trickle bed reactor before use, with a catalyst reduction pressure of 0 to 0.5 MPa, a H2 / N2 mixed atmosphere, a flow rate of 50 ml / min to 150 ml / min, a reduction temperature of 230°C to 350°C, and a reduction time of 3h to 6h;

[0032] The dehydrogenation reaction temperature is 160℃~210℃; the liquid mass space velocity of 1,4-pentanediol is 0.05h -1 ~0.25h -1 .

[0033] The catalyst for preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol is used in the reaction of preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol.

[0034] A method for preparing a catalyst for dehydrogenating 1,4-pentanediol to prepare γ-valerolactone, characterized in that the preparation method is any one of Schemes 1 to 7;

[0035] Option 1

[0036] 11.33 g Cu(NO3)2·3H2O, 96.6 g Zn(NO3)2·6H2O and 7.12 g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and DMF with a volume ratio of 0.3:1 to prepare a 1 L solution with a metal Cu mass concentration of 3.00 g / L, a metal Zn mass concentration of 19.50 g / L and a metal Pr mass concentration of 2.31 g / L. The Cu salt mixed solution was ultrasonically dissolved; after uniform dissolution, 20g triethanolamine complexing agent and 8g SUAEIHDI structure directing agent were added in sequence, and ultrasonically dissolved for 0.5h. After complete dissolution, the suspension was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension; the uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 110℃ for 24h. After cooling, the precipitate was washed 3-5 times with deionized water and DMF by centrifugation, dried in a drying oven at 100℃ for 10h, and then calcined in a muffle furnace at 500℃ for 3h to obtain a composite metal oxide catalyst. x -ZnO is catalyst No. 1;

[0037] Option 2

[0038] 16.99g Cu(NO3)2·3H2O, 85.07g Zn(NO3)2·6H2O and 13.46g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.3:1 to prepare a 1L metal salt mixed solution with a metal Cu mass concentration of 4.50g / L, a metal Zn mass concentration of 17.16g / L and a metal Pr mass concentration of 4.35g / L. Ultrasonic dissolution was performed; after uniform dissolution, 15g triethanolamine complexing agent and 8g The SHAEIHDI structure directing agent was ultrasonically dissolved for 0.5 h. After complete dissolution, it was stirred in a water bath at 80 ° C for 1 h to obtain a uniform suspension. The uniform suspension was then transferred to a 100 ml high-pressure hydrothermal autoclave and aged at 100 ° C for 36 h. After cooling, the precipitate was washed 3 to 5 times with deionized water and ethanol by centrifugation, dried in a drying oven at 120 ° C for 10 h, and then calcined in a muffle furnace at 500 ° C for 5 h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 2;

[0039] Option 3

[0040] 14.29g CuCl2·H2O, 32.32g ZnCl2 and 10.96g PrCl3·7H2O were weighed and dissolved in a mixed solution of deionized water and DMF with a volume ratio of 0.3:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 15.41g / L and a metal Pr mass concentration of 4.14g / L. Ultrasonic dissolution was performed; after uniform dissolution, 15g triethanolamine complexing agent and 10g SUAEIHDI structure directing agent, and then ultrasonically dissolved for 0.5h. After complete dissolution, it was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension. The uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 120℃ for 30h. After cooling, the precipitate was washed 3 to 5 times with deionized water and DMF by centrifugation, dried in a drying oven at 90℃ for 12h, and then calcined in a muffle furnace at 500℃ for 4h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 3;

[0041] Option 4

[0042] 22.65g Cu(NO3)2·3H2O, 90.64g Zn(NO3)2·6H2O and 3.16g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.5:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 18.30g / L and a metal Pr mass concentration of 1.02g / L. Ultrasonic dissolution was performed; after uniform dissolution, 20g triethanolamine complexing agent and 10g SUAEIHDI structure directing agent, and then ultrasonically dissolved for 0.5h. After complete dissolution, it was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension. The uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 110℃ for 36h. After cooling, the precipitate was washed 3 to 5 times with deionized water and DMF by centrifugation, dried in a drying oven at 100℃ for 12h, and then calcined in a muffle furnace at 400℃ for 5h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 4;

[0043] Plan 5

[0044] 22.65g Cu(NO3)2·3H2O, 76.31g Zn(NO3)2·6H2O and 12.66g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.3:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 15.41g / L and a metal Pr mass concentration of 4.14g / L. Ultrasonic dissolution was performed; after uniform dissolution, 20g triethanolamine complexing agent and 12g The SHAEIHDI structure directing agent was ultrasonically dissolved for 0.5 h. After complete dissolution, it was stirred in a water bath at 80 ° C for 1 h to obtain a uniform suspension. The uniform suspension was then transferred to a 100 ml high-pressure hydrothermal autoclave and aged at 120 ° C for 30 h. After cooling, the precipitate was washed 3 to 5 times with deionized water and DMF by centrifugation, dried in a drying oven at 100 ° C for 10 h, and then calcined in a muffle furnace at 500 ° C for 4 h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 5;

[0045] Plan 6

[0046] 11.33 g Cu(NO3)2·3H2O, 85.87 g Zn(NO3)2·6H2O and 14.24 g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.5:1 to prepare a 1 L solution with a metal Cu mass concentration of 3.00 g / L, a metal Zn mass concentration of 17.33 g / L and a metal Pr mass concentration of 4.60 g / L. The Cu salt mixed solution was ultrasonically dissolved; after uniform dissolution, 20g triethanolamine complexing agent and 8g SUAEIHDI structure directing agent were added in sequence, and ultrasonically dissolved for 0.5h. After complete dissolution, the suspension was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension; the uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 110℃ for 24h. After cooling, the precipitate was washed 3-5 times with deionized water and DMF by centrifugation, dried in a drying oven at 80℃ for 10h, and then calcined in a muffle furnace at 500℃ for 3h to obtain a composite metal oxide catalyst. x -ZnO is catalyst No. 6;

[0047] Plan 7

[0048] 22.65g Cu(NO3)2·3H2O, 81.10g Zn(NO3)2·6H2O and 9.49g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and DMF with a volume ratio of 0.5:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 16.28g / L and a metal Pr mass concentration of 3.06g / L. Ultrasonic dissolution was performed; after uniform dissolution, 18g triethanolamine complexing agent and 10g SUAEIHDI structure directing agent, and then ultrasonically dissolved for 0.5h. After complete dissolution, it was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension. The uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 100℃ for 36h. After cooling, the precipitate was washed 3 to 5 times with deionized water and ethanol by centrifugation, dried in a drying oven at 110℃ for 10h, and then calcined in a muffle furnace at 500℃ for 5h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 7.

[0049] The present invention adopting the above technical solution has the following beneficial effects compared with the prior art: the catalyst prepared by the present invention has a low active metal Cu content, a large specific surface area, good active metal dispersion and high activity.

[0050] The catalyst prepared by the present invention generates highly dispersed active Cu sites, abundant basic sites and Pr 3+ -O v -Pr 3+ Defective structures and favorable Cu-O-Zn and Cu-O-Pr interface sites. The unique synergistic effects among surface metal sites, basic sites, defective structures, and Cu-O-Zn and Cu-O-Pr interfaces significantly enhance the efficiency of 1,4-pentanediol dehydrogenation to γ-valerolactone.

[0051] The catalytic reaction conditions are mild (temperature <200°C). In a trickle bed, the conversion rate of 1,4-pentanediol is greater than 99%, and the selectivity of γ-valerolactone is greater than 97%. Compared with other high-temperature conditions, the operation is easy to control and safer, realizing the green nature of the reaction.

[0052] The catalyst prepared by the present invention has good stability, and its catalytic activity does not decrease significantly after continuous operation for 200 hours, and has good industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to further illustrate the present invention, the following is further described with reference to the accompanying drawings:

[0054] Figure 1A typical SEM of the catalyst;

[0055] Figure 2 This is a diagram proving that the catalyst has high stability;

[0056] Figure 3 The composition and structure of the catalyst are shown in Table 1;

[0057] Figure 4 The catalyst evaluation conditions and evaluation results are shown in Table 2;

[0058] Figure 5 This is the reaction formula for the dehydrogenation of 1,4-pentanediol to prepare GVL. DETAILED DESCRIPTION

[0059] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0060] In response to the defects of existing processes, the present invention provides a preparation method and application of a catalyst for catalyzing the dehydrogenation of 1,4-pentanediol to prepare γ-valerolactone. The catalyst has a simple preparation process, is non-toxic and pollution-free, has the advantages of low active metal Cu content, high catalytic activity and good stability, and has good industrial application prospects.

[0061] The catalyst used in the present invention is Cu / PrO x -ZnO.

[0062] Among them, the mass ratio of Cu:Pr:Zn is m(Cu):m(Pr):m(Zn)=(0.07~0.52):(0.04~0.34):1

[0063] The catalyst of the present invention contains Cu, ZnO and PrO x The invention discloses a plurality of components. At the same time, a structure-directing agent 2-undecyl (heptadecanyl)-1-formamidoethyl imidazoline hexanediamine quaternary ammonium salt (SUAEIHDI, SHAEIHDI) gemini surfactant is introduced in the catalyst preparation process to control the pore structure in the catalyst. In addition, the imidazoline gemini surfactant has a special molecular structure similar to a "triblock" polymer. The strong chemical adsorption and bonding effect of the N atoms and O atoms in its structure on metal ions can inhibit or promote the growth of certain crystal faces, thereby effectively controlling the catalyst morphology. At the same time, a weak base complexing agent triethanolamine is introduced. Based on the characteristic that triethanolamine can be uniformly hydrolyzed to release OH under hydrothermal conditions, Cu can be achieved. 2+ , Zn 2+ and Pr 3+ The ions are evenly complexed to form [M(OH)4] 2- (M refers to Cu 2+ 、Zn 2+ 、Pr3+ ) precursor and {[M(OH)4]2-TEA} ligand, which are thermally decomposed and converted into layered multi-level porous nanosheet composite metal oxides during the hydrothermal-calcination process. During the reduction process, the catalyst produces highly dispersed active Cu sites, abundant basic sites and Pr 3+ -O v -Pr 3+ Defect structure and favorable Cu-O-Pr and Cu-O-Zn interface sites. The unique synergistic effects among surface metal sites, basic sites, defect structure, and Cu-O-Pr and Cu-O-Zn interfaces contribute to the enhanced efficiency of the dehydrogenation of 1,4-pentanediol to γ-valerolactone.

[0064] Furthermore, the specific surface area of ​​the catalyst is 120m 2 / g~180m 2 / g, with a multi-level pore distribution, of which pores smaller than 2nm account for 2% to 10%, pores between 2nm and 15nm account for 67% to 90%, and the remainder are macropores. Mesopores facilitate the diffusion and mass transfer of reactant molecules, thereby kinetically promoting the catalytic reaction.

[0065] According to another aspect of the present invention, there is provided a method for preparing the catalyst for catalyzing the dehydrogenation of 1,4-pentanediol to prepare γ-valerolactone, comprising:

[0066] Copper salt, zinc salt, and praseodymium salt are dissolved in a mixed solution of deionized water and an organic solvent to prepare a mixed metal salt solution, which is then ultrasonically dissolved. After uniform dissolution, a complexing agent and a structure-directing agent are sequentially added, followed by ultrasonic dissolution for 0.5 to 1 hour. After complete dissolution, the suspension is stirred in a water bath at 60°C to 80°C for 0.5 to 1 hour to obtain a uniform suspension. The uniform suspension is then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 90°C to 180°C for 6 to 72 hours. After cooling, the precipitate is washed 3 to 5 times with deionized water and ethanol by centrifugation, dried in a drying oven at 80°C to 150°C for 8 to 16 hours, and then calcined in a muffle furnace at 300°C to 700°C for 3 to 5 hours to obtain a composite metal oxide catalyst.

[0067] The copper salt, zinc salt and praseodymium salt described in the above method are soluble salts of copper salt, zinc salt and praseodymium salt, such as Cu(NO3)2·3H2O, Zn(NO3)2·6H2O, Pr(NO3)3·6H2O, CuCl2·H2O, ZnCl2, PrCl3·7H2O, etc.

[0068] The organic solvent in the above method is any one of N,N-dimethylformamide (DMF) and ethanol.

[0069] The complexing agent in the above method is triethanolamine, the structure directing agent is 2-undecyl (heptadecanyl)-1-formamidoethyl imidazoline hexanediamine quaternary ammonium salt (SUAEIHDI, SHAEIHDI) gemini surfactant,

[0070] Furthermore, in the metal salt mixture, the mass concentration of Cu is 1.50 g / L to 7.50 g / L, the mass concentration of Zn is 14.44 g / L to 21.60 g / L, and the mass concentration of Pr is 0.96 g / L to 4.87 g / L.

[0071] Furthermore, in the mixed solution of deionized water and organic solvent, the volume ratio of deionized water to organic solvent is 0.2:1 to 1:1.

[0072] Furthermore, the amount of the complexing agent added is 10g to 30g of triethanolamine per 1L of the metal salt mixture. The amount of the structure directing agent added is 4g to 16g of gemini surfactant per 1L of the metal salt mixture.

[0073] According to another aspect of the present invention, there is provided use of the catalyst for synthesizing γ-valerolactone described above in the dehydrogenation of 1,4-pentanediol to prepare γ-valerolactone.

[0074] The present invention also provides a method for synthesizing γ-valerolactone, wherein the Cu / PrO x -ZnO was used as a catalyst to catalyze the dehydrogenation of 1,4-pentanediol to produce γ-valerolactone in a trickle bed reactor.

[0075] Furthermore, the catalyst is in situ reduced in a trickle bed reactor before use, with a catalyst reduction pressure of 0 to 0.5 MPa, an H2 / N2 mixed atmosphere, a flow rate of 50 ml / min to 150 ml / min, a reduction temperature of 230°C to 350°C, and a reduction time of 3h to 6h.

[0076] Furthermore, the dehydrogenation reaction temperature is 160°C to 210°C; the liquid mass space velocity of 1,4-pentanediol is 0.05h -1 ~0.25h -1 .

[0077] According to the above synthesis method, under solvent-free conditions, in a trickle bed reactor, the conversion rate of 1,4-pentanediol is greater than 99%, and the yield of the target product γ-valerolactone is greater than 97%.

[0078] The present invention is further illustrated by the following examples, but is not limited to the following examples.

[0079] Experimental Example 1

[0080] 11.33g Cu(NO3)2·3H2O, 96.6g Zn(NO3)2·6H2O and 7.12g Pr(NO3)3·6H2O were weighed respectively and dissolved in a mixed solution of deionized water and DMF with a volume ratio of 0.3:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 3.00g / L, a metal Zn mass concentration of 19.50g / L, and a metal Pr mass concentration of 2.31g / L. The solution was ultrasonically dissolved. After uniform dissolution, 20g triethanolamine complexing agent and 8g SUAEIHDI structure directing agent were added in sequence, and ultrasonic dissolution was continued for 0.5h. After complete dissolution, the solution was stirred in a water bath at 80℃ for 1h to obtain a uniformly mixed suspension. The mixed suspension was then transferred to a 100 ml high pressure hydrothermal autoclave and aged at 110 ° C for 24 h. After cooling, the precipitate was washed 3 to 5 times with deionized water and DMF by centrifugation, dried in a drying oven at 100 ° C for 10 h, and then calcined in a muffle furnace at 500 ° C for 3 h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 1.

[0081] Example 2

[0082] 16.99g Cu(NO3)2·3H2O, 85.07g Zn(NO3)2·6H2O and 13.46g Pr(NO3)3·6H2O were weighed respectively and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.3:1 to prepare a 1L metal salt mixed solution with a metal Cu mass concentration of 4.50g / L, a metal Zn mass concentration of 17.16g / L, and a metal Pr mass concentration of 4.35g / L, and ultrasonically dissolved them; after uniform dissolution, 15g triethanolamine complexing agent and 8g SHAEIHDI structure directing agent were added in sequence, and ultrasonically dissolved for another 0.5h. After complete dissolution, stir in a water bath at 80℃ for 1h to obtain a uniformly mixed suspension. The mixed suspension was then transferred to a 100 ml high pressure hydrothermal autoclave and aged at 100 ° C for 36 h. After cooling, the precipitate was washed 3 to 5 times with deionized water and ethanol by centrifugation, dried in a drying oven at 120 ° C for 10 h, and then calcined in a muffle furnace at 500 ° C for 5 h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 2.

[0083] Example 3

[0084] 14.29 g of CuCl2·H2O, 32.32 g of ZnCl2, and 10.96 g of PrCl3·7H2O were respectively weighed and dissolved in a mixed solution of deionized water and DMF with a volume ratio of 0.3:1 to prepare a 1 L Cu salt mixed solution with a metal Cu mass concentration of 6.00 g / L, a metal Zn mass concentration of 15.41 g / L, and a metal Pr mass concentration of 4.14 g / L. Ultrasonic dissolution was performed; after uniform dissolution, 15 g of triethanolamine complexing agent and 10 g of SUAEIHDI structure directing agent were added in sequence, and ultrasonic dissolution was continued for 0.5 h. After complete dissolution, the mixture was stirred in a water bath at 80°C for 1 h to obtain a uniformly mixed suspension. The mixed suspension was then transferred to a 100 ml high pressure hydrothermal autoclave and aged at 120 ° C for 30 h. After cooling, the precipitate was washed 3 to 5 times with deionized water and DMF by centrifugation, dried in a drying oven at 90 ° C for 12 h, and then calcined in a muffle furnace at 500 ° C for 4 h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 3.

[0085] Example 4

[0086] 22.65g Cu(NO3)2·3H2O, 90.64g Zn(NO3)2·6H2O and 3.16g Pr(NO3)3·6H2O were weighed respectively and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.5:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 18.30g / L, and a metal Pr mass concentration of 1.02g / L. Ultrasonic dissolution was performed; after uniform dissolution, 20g triethanolamine complexing agent and 10g SUAEIHDI structure directing agent were added in sequence, and ultrasonic dissolution was continued for 0.5h. After complete dissolution, the mixture was stirred in a water bath at 80℃ for 1h to obtain a uniformly mixed suspension. The mixed suspension was then transferred to a 100 ml high pressure hydrothermal autoclave and aged at 110 ° C for 36 h. After cooling, the precipitate was washed 3 to 5 times with deionized water and DMF by centrifugation, dried in a drying oven at 100 ° C for 12 h, and then calcined in a muffle furnace at 400 ° C for 5 h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 4.

[0087] Example 5

[0088] Take 22.65g Cu(NO3)2·3H2O, 76.31g Zn(NO3)2·6H2O and 12.66g Pr(NO3)3·6H2O respectively, and dissolve them in a mixed solution of deionized water and ethanol with a volume ratio of 0.3:1, to prepare a 1L Cu salt mixed solution with a Cu metal mass concentration of 6.00g / L, a Zn metal mass concentration of 15.41g / L and a Pr metal mass concentration of 4.14g / L, and then perform ultrasonic dissolution; after uniform dissolution, add 20g of triethanolamine complexing agent and 12g of SHAEIHDI structure directing agent in sequence, and then perform ultrasonic dissolution for 0.5h; after complete dissolution, stir in a water bath at 80℃ for 1h to obtain a uniformly mixed suspension. Then transfer the uniformly mixed suspension into a 100ml high-pressure hydrothermal kettle, and age at 120℃ for 30h; after cooling, wash the precipitate with deionized water and DMF by centrifugation for 3-5 times, dry in a 100℃ drying box for 10h, and then calcine in a muffle furnace at 500℃ for 4h to obtain a composite metal oxide catalyst; the obtained Cu / PrO x -ZnO is No. 5 catalyst.

[0089] Example 6

[0090] Take 22.65g Cu(NO3)2·3H2O, 76.31g Zn(NO3)2·6H2O and 12.66g Pr(NO3)3·6H2O respectively, and dissolve them in a mixed solution of deionized water and ethanol with a volume ratio of 0.3:1, to prepare a 1L Cu salt mixed solution with a Cu metal mass concentration of 6.00g / L, a Zn metal mass concentration of 15.41g / L and a Pr metal mass concentration of 4.14g / L, and then perform ultrasonic dissolution; after uniform dissolution, add 20g of triethanolamine complexing agent and 12g of SHAEIHDI structure directing agent in sequence, and then perform ultrasonic dissolution for 0.5h; after complete dissolution, stir in a water bath at 80℃ for 1h to obtain a uniformly mixed suspension. Then transfer the uniformly mixed suspension into a 100ml high-pressure hydrothermal kettle, and age at 120℃ for 30h; after cooling, wash the precipitate with deionized water and DMF by centrifugation for 3-5 times, dry in a 100℃ drying box for 10h, and then calcine in a muffle furnace at 500℃ for 4h to obtain a composite metal oxide catalyst; the obtained Cu / PrO x -ZnO is No. 6 catalyst.

[0091] Example 7

[0092] 22.65g Cu(NO3)2·3H2O, 81.10g Zn(NO3)2·6H2O and 9.49g Pr(NO3)3·6H2O were weighed respectively and dissolved in a mixed solution of deionized water and DMF with a volume ratio of 0.5:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 16.28g / L, and a metal Pr mass concentration of 3.06g / L. Ultrasonic dissolution was performed; after uniform dissolution, 18g triethanolamine complexing agent and 10g SUAEIHDI structure directing agent were added in sequence, and ultrasonic dissolution was continued for 0.5h. After complete dissolution, the mixture was stirred in a water bath at 80℃ for 1h to obtain a uniformly mixed suspension. The mixed suspension was then transferred to a 100 ml high pressure hydrothermal autoclave and aged at 100 ° C for 36 h. After cooling, the precipitate was washed 3 to 5 times with deionized water and ethanol by centrifugation, dried in a drying oven at 110 ° C for 10 h, and then calcined in a muffle furnace at 500 ° C for 5 h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 7.

[0093] The composition, structural characteristics and morphology of catalysts 1-6 were characterized by ICP-OES, N2-physical adsorption-desorption and SEM characterization techniques. The results are listed in Table 1. The mass ratio of Cu:Pr:Zn in the catalyst is m(Cu):m(Pr):m(Zn)=(0.07~0.52):(0.04~0.34):1. The specific surface area of ​​the catalyst is 120m 2 / g~180m 2 / g, showing a multi-level pore distribution, of which pores with a diameter of less than 2nm account for 2% to 10%, 2nm to 15nm account for 67% to 90%, and the rest are macropores. The catalyst has a hierarchical multi-level pore nanosheet structure (typical SEM of the catalyst is shown in Figure 2). Figure 1 ).

[0094] Table 1 Composition and structure of catalyst

[0095]

[0096]

[0097] Example 8

[0098] The above catalysts 1 to 7 were used for the dehydrogenation of 1,4-pentanediol in a trickle bed reactor. x-ZnO is used as a catalyst, and under solvent-free conditions, 1,4-pentanediol is efficiently dehydrogenated to prepare γ-valerolactone. The catalyst reduction pressure is 0-0.5 MPa, H2 / N2 mixed atmosphere, flow rate is 50 ml / min-150 ml / min, reduction temperature is 230℃-350℃, and reduction time is 3h-6h. The dehydrogenation reaction temperature is 160℃-210℃; the liquid mass space velocity of 1,4-pentanediol is 0.05h -1 ~0.25h -1 Under the reaction conditions, the conversion of 1,4-pentanediol was greater than 99%, and the selectivity of γ-valerolactone was greater than 97%. The results are listed in Table 2 below under Catalyst Evaluation Conditions and Results.

[0099] Table 2 Catalyst evaluation conditions and evaluation results

[0100]

[0101]

[0102] Example 9

[0103] The catalyst No. 5 prepared above was used to catalyze the dehydrogenation reaction of 1,4-pentanediol under the conditions of No. 8. The catalyst ran stably for 200 hours (such as Figure 2 ), the catalytic activity did not decrease significantly, indicating that the catalyst has high stability.

[0104] The above experiments show that the catalyst prepared by the present invention has high activity and stability and has potential industrial application value.

[0105] In general, the present invention relates to a preparation method and application of a catalyst for catalyzing the dehydrogenation of 1,4-pentanediol to prepare γ-valerolactone, wherein the catalyst is Cu / PrO x -ZnO. Soluble salts of copper salt, zinc salt, and praseodymium salt are dissolved in a mixed solution of deionized water and an organic solvent and ultrasonically dissolved. Then, a complexing agent and a structure-directing agent are added in sequence. After ultrasonic dissolution again, the mixture is transferred to a 100ml high-pressure hydrothermal autoclave and aged at 90°C to 180°C for 6h to 72h. After cooling, the mixture is washed, dried, and calcined to obtain nanosheet Cu / PrO with a hierarchical multi-level porous structure. x-ZnO catalyst. This catalyst achieves efficient catalytic conversion of 1,4-pentanediol to γ-valerolactone in a trickle bed reactor at 160°C to 210°C, without solvent. The 1,4-pentanediol conversion rate exceeds 99%, and the selectivity for γ-valerolactone exceeds 97%. The catalyst exhibits excellent stability, with no significant decrease in catalytic activity after 200 hours of continuous operation. The catalyst possesses a hierarchical, multi-level porous nanosheet structure, abundant basic and defect sites, good active metal dispersion, high activity, ease of recovery, high stability, and high product yield.

[0106] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications are intended to fall within the scope of the claims.

Claims

1. A catalyst for preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol, characterized in that: The catalyst is Cu / PrO x -ZnO; Among them, Cu: The mass ratio of Pr:Zn is m(Cu):m(Pr):m(Zn):=(0.07~0.52):(0.04~0.34):

1.

2. A method for preparing a catalyst for dehydrogenating 1,4-pentanediol to produce γ-valerolactone, characterized in that: The following steps are included: Dissolve copper salt, zinc salt and praseodymium salt in a mixed solution of deionized water and an organic solvent to prepare a metal salt mixed solution, and dissolve it by ultrasonication; wherein the mass ratio of Cu:Pr:Zn is m(Cu):m(Pr):m(Zn):=(0.07-0.52):(0.04-0.34):1; After uniform dissolution, add the complexing agent and structure directing agent in sequence, and then ultrasonically dissolve for 0.5h~1h. After complete dissolution, stir in a water bath at 60℃~80℃ for 0.5h~1h to obtain a uniformly mixed suspension; The mixed suspension was then transferred to a 100 ml high pressure hydrothermal autoclave and aged at 90°C to 180°C for 6h to 72h. After cooling, the precipitate is washed 3 to 5 times with deionized water and ethanol by centrifugation, dried in a drying oven at 80 to 150° C. for 8 to 16 hours, and then calcined in a muffle furnace at 300 to 700° C. for 3 to 5 hours to obtain a composite metal oxide catalyst.

3. The method for preparing a catalyst for preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol according to claim 2, characterized in that: The copper salt, zinc salt and praseodymium salt are selected from any one or more soluble salts of copper salt, zinc salt and praseodymium salt respectively; the organic solvent is any one of N,N-dimethylformamide DMF and ethanol; the complexing agent is triethanolamine, and the structure directing agent is a gemini surfactant which is 2-undecyl (heptadecanyl)-1-formamidoethylimidazoline hexanediamine quaternary ammonium salt.

4. The method for preparing a catalyst for preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol as claimed in claim 2, characterized in that: In the metal salt mixture, the mass concentration of Cu is 1.50 g / L to 7.50 g / L, the mass concentration of Zn is 14.44 g / L to 21.60 g / L, and the mass concentration of Pr is 0.96 g / L to 4.87 g / L; In the mixed solution of deionized water and organic solvent, the volume ratio of deionized water to organic solvent is 0.2:1 to 1:1; The added amount of the complexing agent is 10g to 30g based on the mass of triethanolamine added to 1L of the metal salt mixture; the added amount of the structure directing agent is 4g to 16g based on the mass of gemini surfactant added to 1L of the metal salt mixture.

5. The method for preparing a catalyst for preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol according to claim 2, characterized in that: During the catalyst preparation process, a quaternary ammonium salt of 2-undecyl-1-carboxamidoethyl imidazoline hexanediamine surfactant was introduced as a structure-directing agent to control the pore structure of the catalyst. Furthermore, the imidazoline surfactant has a unique molecular structure similar to a "triblock" polymer. The strong chemical adsorption and bonding of nitrogen and oxygen atoms with metal ions in its structure inhibits or promotes the growth of certain crystal faces, thereby effectively controlling the catalyst morphology. During the catalyst preparation process, a weak base complexing agent triethanolamine TEA was introduced. Based on the property that triethanolamine can be evenly hydrolyzed to release OH under hydrothermal conditions, Cu 2+ , Zn 2+ and Pr 3+ The ions are evenly complexed to form [M(OH)4] 2- Precursor and {[M(OH)4]2-TEA} ligand, M refers to Cu 2+ 、Zn 2+ 、Pr 3+； During the hydrothermal-calcination process, the catalyst is thermally decomposed into a layered multi-level porous nanosheet composite metal oxide; the catalyst has highly dispersed active Cu sites, abundant basic sites and Pr 3+ -O v -Pr 3+ Defective structure and favorable Cu-O-Pr and Cu-O-Zn interface sites; the unique synergistic effect between surface metal sites, basic sites, defective structure and Cu-O-Zn and Cu-O-Pr interfaces helps to improve the efficiency of 1,4-pentanediol dehydrogenation to γ-valerolactone.

6. The method for preparing a catalyst for preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol according to claim 2, characterized in that: The specific surface area of ​​the catalyst is 120 m 2 / g~180m 2 / g, showing a multi-level pore distribution, in which pores smaller than 2nm account for 2% to 10%, pores of 2nm to 15nm account for 67% to 90%, and the rest are macropores with a diameter of 15-30nm.

7. The method for preparing a catalyst for preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol according to claim 2, characterized in that: During the reduction process, the catalyst can generate highly dispersed active Cu sites, abundant basic sites and Pr 3+ -O v -Pr 3+ Defect structure and favorable Cu-O-Zn and Cu-O-Pr interface sites; under the unique synergistic effect between surface metal sites, basic sites, defect structure and Cu-O-Zn and Cu-O-Pr interfaces, the efficiency of 1,4-pentanediol dehydrogenation to γ-valerolactone can be significantly improved.

8. A method for synthesizing γ-valerolactone, characterized in that: Under solvent-free conditions, 1,4-pentanediol is dehydrogenated to prepare γ-valerolactone in a trickle bed reactor using a catalyst; the catalyst is Cu / PrO x -ZnO; Among them, Cu: The mass ratio of Pr:Zn is m(Cu):m(Pr):m(Zn):=(0.07-0.52):(0.04-0.34):1; The catalyst is reduced in situ in a trickle bed reactor before use, with a catalyst reduction pressure of 0 to 0.5 MPa, a H2 / N2 mixed atmosphere, a flow rate of 50 ml / min to 150 ml / min, a reduction temperature of 230°C to 350°C, and a reduction time of 3h to 6h; The dehydrogenation reaction temperature is 160℃~210℃; the liquid mass space velocity of 1,4-pentanediol is 0.05h -1 ~0.25h -1 .

9. Use of the catalyst for preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol as claimed in claim 1 in the reaction of preparing γ-valerolactone by dehydrogenation of 1,4-pentanediol.

10. A method for preparing a catalyst for dehydrogenating 1,4-pentanediol to produce γ-valerolactone, characterized in that: The preparation method is any one of Schemes 1 to 7; Option 1 11.33 g Cu(NO3)2·3H2O, 96.6 g Zn(NO3)2·6H2O and 7.12 g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and DMF with a volume ratio of 0.3:1 to prepare a 1 L solution with a metal Cu mass concentration of 3.00 g / L, a metal Zn mass concentration of 19.50 g / L and a metal Pr mass concentration of 2.31 g / L. The Cu salt mixed solution was ultrasonically dissolved; after uniform dissolution, 20g triethanolamine complexing agent and 8g SUAEIHDI structure directing agent were added in sequence, and ultrasonically dissolved for 0.5h. After complete dissolution, the suspension was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension; the uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 110℃ for 24h. After cooling, the precipitate was washed 3-5 times with deionized water and DMF by centrifugation, dried in a drying oven at 100℃ for 10h, and then calcined in a muffle furnace at 500℃ for 3h to obtain a composite metal oxide catalyst. x -ZnO is catalyst No. 1; Option 2 16.99g Cu(NO3)2·3H2O, 85.07g Zn(NO3)2·6H2O and 13.46g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.3:1 to prepare a 1L metal salt mixed solution with a metal Cu mass concentration of 4.50g / L, a metal Zn mass concentration of 17.16g / L and a metal Pr mass concentration of 4.35g / L. Ultrasonic dissolution was performed; after uniform dissolution, 15g triethanolamine complexing agent and 8g The SHAEIHDI structure directing agent was ultrasonically dissolved for 0.5 h. After complete dissolution, it was stirred in a water bath at 80 ° C for 1 h to obtain a uniform suspension. The uniform suspension was then transferred to a 100 ml high-pressure hydrothermal autoclave and aged at 100 ° C for 36 h. After cooling, the precipitate was washed 3 to 5 times with deionized water and ethanol by centrifugation, dried in a drying oven at 120 ° C for 10 h, and then calcined in a muffle furnace at 500 ° C for 5 h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 2; Option 3 14.29g CuCl2·H2O, 32.32g ZnCl2 and 10.96g PrCl3·7H2O were weighed and dissolved in a mixed solution of deionized water and DMF with a volume ratio of 0.3:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 15.41g / L and a metal Pr mass concentration of 4.14g / L. Ultrasonic dissolution was performed; after uniform dissolution, 15g triethanolamine complexing agent and 10g SUAEIHDI structure directing agent, and then ultrasonically dissolved for 0.5h. After complete dissolution, it was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension. The uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 120℃ for 30h. After cooling, the precipitate was washed 3 to 5 times with deionized water and DMF by centrifugation, dried in a drying oven at 90℃ for 12h, and then calcined in a muffle furnace at 500℃ for 4h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 3; Option 4 22.65g Cu(NO3)2·3H2O, 90.64g Zn(NO3)2·6H2O and 3.16g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.5:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 18.30g / L and a metal Pr mass concentration of 1.02g / L. Ultrasonic dissolution was performed; after uniform dissolution, 20g triethanolamine complexing agent and 10g SUAEIHDI structure directing agent, and then ultrasonically dissolved for 0.5h. After complete dissolution, it was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension. The uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 110℃ for 36h. After cooling, the precipitate was washed 3 to 5 times with deionized water and DMF by centrifugation, dried in a drying oven at 100℃ for 12h, and then calcined in a muffle furnace at 400℃ for 5h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 4; Plan 5 22.65g Cu(NO3)2·3H2O, 76.31g Zn(NO3)2·6H2O and 12.66g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.3:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 15.41g / L and a metal Pr mass concentration of 4.14g / L. Ultrasonic dissolution was performed; after uniform dissolution, 20g triethanolamine complexing agent and 12g The SHAEIHDI structure directing agent was ultrasonically dissolved for 0.5 h. After complete dissolution, it was stirred in a water bath at 80 ° C for 1 h to obtain a uniform suspension. The uniform suspension was then transferred to a 100 ml high-pressure hydrothermal autoclave and aged at 120 ° C for 30 h. After cooling, the precipitate was washed 3 to 5 times with deionized water and DMF by centrifugation, dried in a drying oven at 100 ° C for 10 h, and then calcined in a muffle furnace at 500 ° C for 4 h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 5; Plan 6 11.33 g Cu(NO3)2·3H2O, 85.87 g Zn(NO3)2·6H2O and 14.24 g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and ethanol with a volume ratio of 0.5:1 to prepare a 1 L solution with a metal Cu mass concentration of 3.00 g / L, a metal Zn mass concentration of 17.33 g / L and a metal Pr mass concentration of 4.60 g / L. The Cu salt mixed solution was ultrasonically dissolved; after uniform dissolution, 20g triethanolamine complexing agent and 8g SUAEIHDI structure directing agent were added in sequence, and ultrasonically dissolved for 0.5h. After complete dissolution, the suspension was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension; the uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 110℃ for 24h. After cooling, the precipitate was washed 3-5 times with deionized water and DMF by centrifugation, dried in a drying oven at 80℃ for 10h, and then calcined in a muffle furnace at 500℃ for 3h to obtain a composite metal oxide catalyst. x -ZnO is catalyst No. 6; Plan 7 22.65g Cu(NO3)2·3H2O, 81.10g Zn(NO3)2·6H2O and 9.49g Pr(NO3)3·6H2O were weighed and dissolved in a mixed solution of deionized water and DMF with a volume ratio of 0.5:1 to prepare a 1L Cu salt mixed solution with a metal Cu mass concentration of 6.00g / L, a metal Zn mass concentration of 16.28g / L and a metal Pr mass concentration of 3.06g / L. Ultrasonic dissolution was performed; after uniform dissolution, 18g triethanolamine complexing agent and 10g SUAEIHDI structure directing agent, and then ultrasonically dissolved for 0.5h. After complete dissolution, it was stirred in a water bath at 80℃ for 1h to obtain a uniform suspension. The uniform suspension was then transferred to a 100ml high-pressure hydrothermal autoclave and aged at 100℃ for 36h. After cooling, the precipitate was washed 3 to 5 times with deionized water and ethanol by centrifugation, dried in a drying oven at 110℃ for 10h, and then calcined in a muffle furnace at 500℃ for 5h to obtain a composite metal oxide catalyst. The obtained Cu / PrO x -ZnO is catalyst No. 7.

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