A catalyst for hydrogenation of maleic anhydride to gamma-butyrolactone with nano-gold as core, a preparation method and applications thereof

Abstract

This invention discloses a catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a nano-gold core, its preparation method, and its application, belonging to the field of core-shell catalyst technology. The catalyst of this invention consists of a nano-Au core and a C-Cu-M... x O y The catalyst is composed of a SiO2 shell with a pore size of 2.1 nm to 3.2 nm. The catalyst preparation process of this invention includes the following steps: preparing an Au sol solution; preparing a copper salt mixed solution containing organic ligands, metal auxiliary salts, surfactants, precipitants, and a silicon source; adding the Au sol solution to the copper salt mixed solution to obtain catalyst powder; pressing the catalyst powder into tablets; and reducing the pressed catalyst by heating to finally obtain a C-Cu-M catalyst with nano-Au particles as the core and a SiO2 shell confining it. x O y Catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone. Based on several structural advantages, the catalyst of this invention exhibits excellent activity, selectivity, and stability in the hydrogenation of maleic anhydride.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of core-shell structure catalysts, and specifically relates to a maleic anhydride hydrogenation catalyst with nano gold as an inner core for preparing gamma-butyrolactone, a preparation method and application. BACKGROUND

[0002] Gamma-butyrolactone (GBL) is a very important basic chemical raw material and is widely used and researched in the fields of organic synthesis, new energy materials, drug synthesis and the like. It is a solvent with excellent performance and high conductivity, and its downstream product N-methyl pyrrolidone can be used as a cleaning solvent, electrolyte and the like for lithium ion batteries and capacitors. In addition, many five-membered ring molecules derived from GBL can be used for new drug research and development and synthesis in the medical field, such as ciprofloxacin, cerebrolysin, vitamin B, tranquilizer gamma-hydroxybutyric acid, acetylcholinesterase inhibitor and the like. With the rapid development of China's economy, especially the development of the lithium ion battery industry, the demand for GBL in China shows a trend of increasing year by year.

[0003] Compared with the two routes of synthesizing GBL by dehydrogenation of 1,4-butanediol (BDO) and synthesizing GBL by esterification and hydrogenation of maleic anhydride, synthesizing GBL by direct hydrogenation of maleic anhydride has the advantages of short process flow, great raw material cost advantage and high product quality. The main process for synthesizing GBL by direct hydrogenation of maleic anhydride in industry is a normal pressure gas phase hydrogenation process, and a supported copper-based catalyst is selected.

[0004] The main catalyst currently used is a multi-component catalyst composed of CuO, ZnO and Al2O3 [such as CN1298759A, CN1358568A, US 5122485, CN1058400A and CN1111167A], and Ba, Pd and Pt are added as additives. Due to the low Tammann temperature of Cu species, a series of problems such as agglomeration of nano particles, poor mechanical strength and short service life of the catalyst cannot be avoided during use of the catalyst. In addition, the strong acid centers existing on the surface of the catalyst easily lead to the generation of high polymers, causing carbon deposition and deactivation of the catalyst. SUMMARY

[0005] The purpose of the present application is to solve the problems of easy agglomeration of active components, short service life and easy carbon deposition and deactivation of the existing copper-based catalyst in the reaction of synthesizing gamma-butyrolactone by hydrogenation of maleic anhydride, and a maleic anhydride hydrogenation catalyst with nano gold as an inner core and SiO2 shell layer limiting the inner core, a preparation method and application are provided.

[0006] The present application is realized by the following technical scheme:

[0007] According to the first aspect of the present application, a catalyst for hydrogenation of maleic anhydride to γ-butyrolactone with nano-gold as the core is provided, which is composed of a nano Au core and a C-Cu-M x O y @mSiO2 shell layer, the diameter of the nano Au core is 11 nm-33 nm, the thickness of the C-Cu-M x O y @mSiO2 shell layer is 55 nm-75 nm, and the pore size is 2.1 nm-3.2 nm.

[0008] Further, in the catalyst, the mass fraction of C is 1.3-3.3 %, the mass fraction of Cu is 24.5-43.5 %, the mass fraction of M x O y is 1.8-4.2 %, the mass fraction of Au is 0.18-0.67 %, and the rest is SiO2; wherein, Cu exists in the form of Cu 0 with electron-rich state and Cu + with electron-deficient state, and the atomic ratio of Cu + / (Cu + + Cu 0 ) is 15 %-28 %.

[0009] According to the second aspect of the present application, a preparation method of the above-mentioned catalyst for hydrogenation of maleic anhydride to γ-butyrolactone with nano-gold as the core is provided, which comprises the following steps:

[0010] Step one: uniformly mix the heated and boiled aqueous chloroauric acid solution with the aqueous sodium citrate solution under strong stirring, continue to boil for 30 min-60 min, and obtain an Au sol solution.

[0011] Step two: prepare a mixed solution with a fixed alcohol / water ratio, and dissolve the copper salt, organic ligand, metal additive salt, and surfactant in the mixed solution as the solvent, and then add the precipitant and silicon source in sequence, and stir uniformly to obtain a copper salt mixed solution.

[0012] Step three: add the Au sol solution prepared in step one to the copper salt mixed solution prepared in step two, ultrasonic treat for 20 min-50 min, heat under the irradiation of deuterium lamp at 80-110 ℃ for 3-10 h, and then transfer to a hydrothermal kettle, and heat to 120-180 ℃ for hydrothermal treatment for 5-10 h.

[0013] Step four: after the reaction is completed, centrifugally separate the mixed solution, wash the obtained precipitate with distilled water and ethanol for 3-5 times to remove impurities, dry at 80-110 ℃ for 10-16 h, and then calcine at 350 ℃-650 ℃ for 3 h-6 h to obtain a catalyst powder.

[0014] Step five: add carbon fiber, graphite powder, graphene and organic carbon source into the catalyst powder obtained in step four, mix uniformly and press into a tablet to obtain a tablet-shaped catalyst.

[0015] Step six: load the tablet-shaped catalyst prepared in step five into an atmosphere furnace, reduce by heating after passing in H2 / N2 mixed gas, and finally obtain the catalyst for hydrogenation of maleic anhydride to γ-butyrolactone with nano gold as the core, wherein the nano gold particles are the core and the SiO2 shell is limited.

[0016] Further, in step one, the mass concentration of chloroauric acid in the aqueous chloroauric acid solution is 0.1 Kg / m 3 ~ 0.2 Kg / m 3 The mass concentration of sodium citrate in the aqueous sodium citrate solution is 2 Kg / m 3 ~17 Kg / m 3 The aqueous sodium citrate solution and the aqueous chloroauric acid solution are mixed in a volume ratio of 2:100~6:100, and the size of the Au nanoparticle in the obtained Au sol solution is 11 nm~33 nm.

[0017] Further, in step two, the volume ratio of distilled water to ethanol in the prepared solvent is 1:10~5:10; the copper salt is selected from one or both of copper nitrate trihydrate and copper nitrate hexahydrate, the mass concentration of copper in the copper salt mixed solution is 2.5 Kg / m 3 ~4.5 Kg / m 3 The organic ligand is selected from one or both of 3,5-pyrazole dicarboxylic acid and 1,10-phenanthroline, the mass concentration of the organic ligand in the copper salt mixed solution is 0.0026 Kg / m 3 ~0.0164 Kg / m 3 The metal additive salt is selected from one or more of zinc nitrate hexahydrate, zirconium nitrate pentahydrate, cerium nitrate hexahydrate, and nickel nitrate hexahydrate, the mass concentration of the metal additive in the copper salt mixed solution is calculated in the form of its oxide M x O y , which is 0.20 Kg / m 3 ~0.6 Kg / m 3 The surfactant is selected from one or both of polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB), the mass concentration of the surfactant in the copper salt mixed solution is 2 Kg / m 3 ~6 Kg / m 3 The precipitating agent is urea, the mass concentration of urea in the copper salt mixed solution is 8.9 Kg / m 3 ~16.5 Kg / m 3 The silicon source is selected from one or both of tetraethyl orthosilicate (TEOS) and silica sol, the mass concentration of the silicon source in the copper salt mixed solution is calculated as SiO2, which is 4.8 Kg / m3 7.3 Kg / m 3 .

[0018] Further, in step three, the volume ratio of the copper salt mixed solution to the Au sol solution is 3:1.035~3:1.811; the wavelength of the deuterium lamp is 190 nm~400 nm, and the power is 30 W.

[0019] Further, in step four, the calcination temperature is 400℃~500℃.

[0020] Further, in step five, the mass fraction of carbon fibers, graphite powder, graphene and organic carbon source in the catalyst powder is 0.1%~0.3%, 1~3%, 0.1%~0.2% and 5%~10% respectively; the organic carbon source is one or both of citric acid and sucrose; the obtained tablet-shaped catalyst is columnar, and the specification of height x diameter is 3mm x 3mm, 4mm x 4mm or 5mm x 5mm.

[0021] Further, in step six, the volume fraction of H2 in the H2 / N2 mixed gas is 0.5%~5%, the reduction temperature is 150℃~350℃, and the time is 1 h~12 h.

[0022] According to a third aspect of the present application, the application provides the use of the above-mentioned catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone or the catalyst prepared by the above-mentioned method in the reaction of synthesizing γ-butyrolactone from maleic anhydride and hydrogen.

[0023] The catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with nano-gold as the core obtained by the present application is applied to the heterogeneous system of the gas phase atmospheric pressure hydrogenation of maleic anhydride to γ-butyrolactone, specifically: after mixing hydrogen and maleic anhydride vapor, the gas phase material is reacted through a fixed bed reactor filled with the catalyst, wherein the reactor reaction temperature is 250-330℃, the reaction pressure is lower than 0.5 MPa, the molar ratio of hydrogen to maleic anhydride is 50-200, the liquid weight space velocity of maleic anhydride is 0.03-0.26 hr -1 , the single-pass conversion rate of maleic anhydride is 100%, and the selectivity of γ-butyrolactone can reach 95-98%.

[0024] The catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with nano-gold as the core and the preparation method thereof have the following advantages compared with the existing catalysts:

[0025] (1) In the preparation process of the catalyst of the present application, nano gold particles are introduced as condensation nuclei. Under the irradiation of a deuterium lamp with a wavelength of 190 nm to 400 nm and a power of 30 W, the outer layer of the nano gold particles exhibits electronegativity, which can synergize with the surfactant to effectively guide the ordered growth of Cu and metal additive M species with positive charges around it, and induce the formation of a core-shell structure. The formation of this structure not only reduces the crystallinity of the particles in the shell layer, enables uniform compounding between components, maximizes the synergistic effect between the copper center and the metal additive, and maximizes the exposure of active sites; at the same time, the gold nanoparticles have a long-range electronic regulation effect, which can effectively regulate the electronic valence of the copper species. After reduction, Cu 0 and Cu + species exist in two states, and the Cu + / (Cu + +Cu 0 ) atomic ratio is 15% to 28%, which presents the optimal selectivity of maleic anhydride hydrogenation to γ-butyrolactone, and inhibits the deactivation of the catalyst caused by the change in the valence state of the copper species during the catalytic reaction, thereby improving the stability of the catalyst.

[0026] (2) M x O y additives are introduced into the catalyst of the present application, and M is one or more of zinc, zirconium, cerium, and nickel. These oxygenophilic M exist in the form of oxidation state, which plays two roles, one is to form a strong interaction with Cu, which improves the dispersion of Cu species and inhibits the migration and aggregation of Cu species during preparation and use, which can inhibit the activity decline and irreversible deactivation of the catalyst caused by the aggregation of active components; the other role is that M provides the function of adsorbing oxygen atoms in maleic anhydride, which can enable maleic anhydride molecules to be adsorbed on the surface of the catalyst in multiple sites, realize one-step hydrogenation of maleic anhydride to the target product, and improve the selectivity of the catalyst.

[0027] (3) In the preparation process of the catalyst of the present application, urea is used as a precipitant, and OH - and CO3 2- are generated by slow hydrolysis of urea during heating, which enables uniform precipitation of components and inhibits the local pH from being too high caused by direct addition of traditional precipitants, thereby enabling step-by-step precipitation of Cu and M components and solving the problem of uneven components.

[0028] (4) C species are introduced into the catalyst of the present application in multiple layers, which exist in different forms in the catalyst at different stages and play multiple synergistic effects. First, organic ligands 3,5-pyrazole dicarboxylic acid and 1,10-phenanthroline are added during the preparation of the catalyst, which can form coordination compounds with Cu 2+The complex is formed, and the complex exists in the form of C point around the Cu particles in the subsequent calcination process, which plays a role in dispersing the Cu particles and inhibiting the aggregation of Cu species; secondly, the C element components of carbon fibers, graphite powder and graphene are introduced in the catalyst forming process, the carbon fibers mainly play a role in improving the strength and toughness of the catalyst after forming, the graphite powder acts as a release agent to make the forming more smooth, and the graphene as a two-dimensional sheet structure can act on the surface of the Cu particles and cooperatively inhibit the aggregation of Cu species with the C point formed by the complex, and prevent the occurrence of carbon deposition. In this process, organic carbon sources such as citric acid and sucrose are also introduced, and in the subsequent reduction process, H2, CO and highly active carbon points generated by the decomposition of the organic carbon sources can play the role of a reducing agent, cooperating with H2 in the reducing atmosphere to achieve the slow reduction of CuO species, avoid the catalyst temperature rising caused by the reduction heat release, and maintain the high dispersion of the catalyst. In addition, the presence of carbon point modification can adjust the hydrophobicity and lipophilicity of the catalyst surface, make the catalyst surface appropriately hydrophobic and lipophilic, greatly improve the hydrogenation activity of the catalyst, and at the same time, prevent the hydration damage of the catalyst caused by by-products water, further prolong the service life of the catalyst.

[0029] (5) Mesoporous mSiO2 shell layer, from the preparation point of view, urea is used as a precipitant to slowly increase the pH value of the system, based on the slow hydrolysis rate of the silicon source, the preferential precipitation of Cu and M can be realized, and then the SiO2 coating layer is formed; the presence of surfactants such as CTAB makes the SiO2 coating layer produce mesoporous structures. The presence of the mesoporous mSiO2 shell layer plays an important role, one is to confine Cu and other metal additives in the SiO2 shell layer, which plays a role in inhibiting the aggregation of active components; two is that the mesoporous channels can act as reaction channels to strengthen the mass transfer and heat transfer of reactants and accelerate the reaction rate.

[0030] (6) The catalyst of the present application has multiple advantages in structure, and shows excellent activity, selectivity and service life in the hydrogenation of maleic anhydride. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application, but do not limit the application.

[0032] Figure 1 A high-resolution electron microscope photograph of the catalyst for preparing gamma-butyrolactone from maleic anhydride with nano-gold as the core according to the present application. DETAILED DESCRIPTION

[0033] The present application provides a catalyst for preparing gamma-butyrolactone from maleic anhydride with nano-gold as the core, which comprises a nano-Au core and a C-Cu-M x O yThe diameter of the Au core is 11 nm-33 nm, and the mass fraction of C-Cu-M x O y The thickness of the @mSiO2 shell is 55 nm-75 nm, and the pore size is 2.1 nm-3.2 nm. In the catalyst, the mass fraction of C is 1.3-3.3 %, the mass fraction of Cu is 24.5-43.5 %, and the mass fraction of M x O y The mass fraction of C is 1.8-4.2 %, the mass fraction of Au is 0.18-0.67 %, and the rest is SiO2. Among them, Cu 0 exists in the form of Cu + with electron-rich state and Cu + with electron-deficient state, and the atomic ratio of Cu + / (Cu + +Cu 0 ) is 15 %-28 %.

[0034] The application further provides a preparation method of the above-mentioned catalyst for preparing γ-butyrolactone by hydrogenation of maleic anhydride with a gold nano-particle as a core, comprising the following steps:

[0035] Step one: uniformly mix the heated and boiled chloroauric acid aqueous solution and the sodium citrate aqueous solution under strong stirring, and continue to boil for 30 min-60 min to obtain an Au sol solution.

[0036] In this step, the mass concentration of chloroauric acid in the chloroauric acid aqueous solution is 0.1 Kg / m 3 ~ 0.2 Kg / m 3 , the mass concentration of sodium citrate in the sodium citrate aqueous solution is 2 Kg / m 3 ~17 Kg / m 3 , the sodium citrate aqueous solution and the chloroauric acid aqueous solution are mixed in a volume ratio of 2:100-6:100, and the size of Au nano-particles in the obtained Au sol solution is 11 nm-33 nm, preferably 13 nm-26 nm.

[0037] Step two: prepare a mixed solution with a fixed alcohol / water ratio, and use the mixed solution as a solvent to dissolve copper salt, organic ligand, metal additive salt and surfactant, and then sequentially add a precipitating agent and a silicon source, and uniformly stir to obtain a copper salt mixed solution.

[0038] In this step, the volume ratio of distilled water to ethanol in the prepared solvent is 1:10-5:10; the copper salt is selected from one or both of copper nitrate trihydrate and copper nitrate hexahydrate, and the mass concentration of copper in the copper salt mixed solution is 2.5 Kg / m 3 ~4.5 Kg / m 3; the organic ligand is one or both of 3,5-pyrazole dicarboxylic acid and 1,10-phenanthroline, and the mass concentration of the organic ligand in the copper salt mixed solution is 0.0026 Kg / m 3 0.0164 Kg / m 3 ; the metal additive salt is one or more of zinc nitrate hexahydrate, zirconium nitrate pentahydrate, cerium nitrate hexahydrate, and nickel nitrate hexahydrate, and the mass concentration of the metal additive in the copper salt mixed solution is 0.20 Kg / m x O y form, 0.20 Kg / m 3 0.6 Kg / m 3 ; the surfactant is one or both of polyvinylpyrrolidone and cetyl ammonium bromide, and the mass concentration of the surfactant in the copper salt mixed solution is 2 Kg / m 3 6 Kg / m 3 ; the precipitant is urea, and the mass concentration of the urea in the copper salt mixed solution is 8.9 Kg / m 3 16.5 Kg / m 3 ; the silicon source is one or both of tetraethyl orthosilicate and silica sol, and the mass concentration of the silicon source in the copper salt mixed solution is 4.8 Kg / m 3 7.3 Kg / m 3 .

[0039] Step three: the Au sol solution prepared in step one is added to the copper salt mixed solution prepared in step two, ultrasonic treatment is performed for 20 min to 50 min, under the irradiation of a deuterium lamp, heating reflux is performed at 80 ℃ to 110 ℃ for 3 h to 10 h, and then the mixture is transferred into a hydrothermal kettle and hydrothermal treatment is performed at 120 ℃ to 180 ℃ for 5 h to 10 h.

[0040] In this step, the volume ratio of the copper salt mixed solution to the Au sol solution is 3:1.035 to 3:1.811; the wavelength of the deuterium lamp is 190 nm to 400 nm, and the power is 30 W.

[0041] Step four: after the reaction is completed, the mixture is centrifuged and separated, the obtained precipitate is washed with distilled water and ethanol for 3 to 5 times to remove impurities, and then the precipitate is dried at 80 ℃ to 110 ℃ for 10 h to 16 h, and then calcination is performed at 350 ℃ to 650 ℃ for 3 h to 6 h, to obtain a catalyst powder.

[0042] In this step, the calcination temperature is 400 ℃ to 500 ℃.

[0043] Step five: carbon fibers, graphite powder, graphene, and an organic carbon source are added to the catalyst powder obtained in step four, and then the mixture is uniformly mixed and tablet-pressed to form a tablet-pressed catalyst.

[0044] In the step, the mass fraction of carbon fiber, graphite powder, graphene and organic carbon source in the catalyst powder is 0.1%~0.3%, 1~3%, 0.1%~0.2% and 5%~10% respectively; the organic carbon source is one or both of citric acid and sucrose; the obtained tablet-shaped catalyst is columnar, and the specification of height* diameter is 3mm*3mm, 4mm*4mm or 5mm*5mm.

[0045] In the step, the mass fraction of carbon fiber, graphite powder, graphene and organic carbon source in the catalyst powder is 0.1%~0.3%, 1~3%, 0.1%~0.2% and 5%~10% respectively; the organic carbon source is one or both of citric acid and sucrose; the obtained tablet-shaped catalyst is columnar, and the specification of height* diameter is 3mm*3mm, 4mm*4mm or 5mm*5mm.

[0046] In the step, the volume fraction of H2 in the H2 / N2 mixed gas is 0.5%~5%, the reduction temperature is 150℃~350℃, and the time is 1 h~12 h, preferably 3 h~8 h.

[0047] The application further provides the application of the above-mentioned catalyst for preparing gamma-butyrolactone by hydrogenation of maleic anhydride with nanometer gold as the core or the catalyst for preparing gamma-butyrolactone by hydrogenation of maleic anhydride with nanometer gold as the core prepared by the above-mentioned preparation method in the reaction of synthesizing gamma-butyrolactone from maleic anhydride and hydrogen.

[0048] Further, in order to make the person skilled in the art better understand the application, the technical solutions of the application are further clearly and completely explained in combination with specific examples and reference to the accompanying drawings. It should be noted that the features in the embodiments and examples in the application can be combined with each other without conflict. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application. Example 1

[0049] Preparation of Au sol solution with different Au nanoparticle sizes. As shown in Table 1, 0.2~0.4 Kg of chloroauric acid was dissolved in deionized water, and the volume was made to 2 m 3 , to obtain a chloroauric acid solution with a mass concentration of 0.1~0.2 Kg / m 3 of chloroauric acid, and heated to boiling; 0.4~3.4 Kg of sodium citrate was dissolved in deionized water, and the volume was made to 200 L to obtain a sodium citrate solution with a mass concentration of 2~17 Kg / m 3 . 40~120 L of the sodium citrate solution was taken and heated to boiling, and added to the 2 m 3 boiling chloroauric acid aqueous solution under strong stirring conditions, and continued to boil for 30 min~60 min to obtain an Au sol solution with an Au nanoparticle size of 11~33 nm;

[0050] Table 1. Preparation conditions of Au sol solutions with different particle sizes

[0051] Example 2

[0052] Prepare a copper salt mixed solution according to the amounts of the components listed in Table 2. Weigh the required mass of copper nitrate trihydrate and / or copper nitrate hexahydrate, and the required mass of the organic ligand 3,5-pyrazole dicarboxylic acid and / or 1,10-phenanthroline, and add them to 2 mL of an alcohol-water mixture with a volume ratio of distilled water to ethanol of 1:10 to 5:10. 3 Dissolve by stirring; then weigh out the required mass of one or more of zinc nitrate hexahydrate, zirconium nitrate pentahydrate, cerium nitrate hexahydrate, and nickel nitrate hexahydrate, the required mass of tetraethyl orthosilicate (TEOS) and / or silica sol, the required mass of polyvinylpyrrolidone (PVP) and / or hexadecyl ammonium bromide (CTAB), and the required mass of urea, and add them sequentially to the above-mentioned alcohol-water solution dissolved in copper salt and organic ligand. Dissolve under stirring, and continue to add an alcohol-water solution with a volume ratio of distilled water to ethanol of 1:10 to 5:10 to bring the volume to 3 mL. 3 A copper salt mixed solution was obtained. The mass concentration of copper in the copper salt mixed solution was controlled at 2.5 kg / m³. 3 ~4.5 Kg / m 3 The mass concentration of the organic ligand was controlled at 0.0026 kg / m³. 3 ~0.0164 Kg / m 3 The mass concentration of the metal additive, in terms of its oxide M x O y Formal calculations show that at 0.20 kg / m 3 ~0.60 Kg / m 3 The mass concentration of the silicon source reagent, calculated based on SiO2, is 4.8 kg / m³. 3 -7.3 Kg / m 3 The mass concentration of the surfactant is controlled at 2 kg / m³. 3 ~6 Kg / m 3 The mass concentration of urea in the copper salt mixture was 8.9 kg / m³. 3 ~16.5 Kg / m 3 ;

[0053] Table 2 Wet Chemical Processes

[0054]

[0055] The Au sol solution prepared in Example 1 was added to the above copper salt mixed solution, with a volume ratio of copper salt mixed solution to gold sol solution of 3:1.035 to 3:1.811. The mixture was ultrasonically treated for 20 to 50 minutes, then refluxed at 80 to 110 °C for 3 to 10 hours under a deuterium lamp with a wavelength of 190 nm to 400 nm and a power of 30 W. Afterward, the mixture was transferred to a hydrothermal reactor and hydrothermally treated at 120 to 180 °C for 5 to 10 hours. After the reaction, the mixture was centrifuged, and the resulting precipitate was washed 3 to 5 times with distilled water and ethanol to remove impurities. The precipitate was dried at 80 to 110 °C for 10 to 16 hours and then calcined at 350 to 650 °C for 3 to 6 hours to obtain catalyst powder. The preferred calcination conditions are 400 to 500 °C, as shown in Table 3.

[0056] Table 3 Precipitation process

[0057] Example 3

[0058] 100 kg of the catalyst powder prepared in Example 2 was weighed and added to carbon fiber, graphite powder, graphene, and an organic carbon source according to the specific conditions listed in Table 4. After mixing evenly, the mixture was compressed into tablets. The mass fractions of carbon fiber, graphite powder, graphene, and organic carbon source in the catalyst powder were 0.1%~0.3%, 1~3%, 0.1%~0.2%, and 5%~10%, respectively. The organic carbon source was citric acid and / or sucrose. After compression, the resulting tableted catalyst was columnar with height × diameter specifications of 3 mm × 3 mm, 4 mm × 4 mm, or 5 mm × 5 mm.

[0059] Table 4 Molding conditions

[0060] Example 4

[0061] The prepared catalyst was characterized by high-resolution electron microscopy, such as... Figure 1 As shown, an Au core is formed, surrounded by a C-Cu-M coating. x O y The catalyst has a core-shell structure with an @mSiO2 shell. The composition and physicochemical properties of the prepared catalyst were determined after H2 reduction, as shown in Table 5. The mass fraction of C in the catalyst was 1.3–3.3%, the mass fraction of Cu was 24.5–43.5%, and the mass fraction of M... x O y The mass fraction is 1.8~4.2%, the mass fraction of Au is 0.18~0.67%, and the remainder is SiO2. C-Cu-M x O yThe thickness of the @mSiO2 shell layer is 55 nm-75 nm, and the average pore size is 2.1 nm-3.2 nm. Cu is in an electron-rich state 0 Cu is in an electron-deficient state + Both states exist, Cu + / (Cu + +Cu 0 The atomic ratio of Cu is 15%-28%, and the electron state and atomic ratio of the Cu species are determined by X-ray excited Auger electron spectroscopy.

[0062] Table 5 Composition and physicochemical properties

[0063]

[0064] Note: The Cu and metal oxide content is determined by ICP-AES technology; the C mass fraction is determined by elemental analysis; the shell thickness and Au particle size are obtained by high-resolution electron microscopy combined with particle statistics. Example 5

[0065] The performance of the catalysts was evaluated in a fixed bed reactor, and the results are shown in Table 6. After the catalyst was loaded into a stainless steel fixed bed reactor with an inner diameter of 30 mm (catalyst bed height 1000 mm), it was reduced in a H2 / N2 mixed gas with a H2 volume fraction of 0.5%-5% by electric heating control at a temperature rise of 0.5 ℃ / min-5 ℃ / min to 150 ℃-350 ℃ for 1 h-12 h. The reaction temperature was then adjusted to 250 ℃, the reaction pressure was less than 0.5 MPa, the molar ratio of hydrogen to maleic anhydride was 50-200, and the liquid weight hourly space velocity of maleic anhydride was 0.1-0.26 hr -1 The single-pass conversion of maleic anhydride was 100%, and the selectivity of γ-butyrolactone could reach 95-98%. During the reaction process, when the activity of the catalyst decreased, the reaction temperature was appropriately increased to continue the reaction, and finally the temperature was increased to 330 ℃, and the temperature was no longer increased to complete a reaction cycle. After the catalyst was regenerated, it was re-fed into the next reaction cycle;

[0066] Table 6 Reduction and evaluation results of various catalysts

[0067]

[0068] Note: a The temperature interval at different positions in the bed during the constant temperature reduction process; b Due to the need to appropriately increase the reaction temperature to achieve the best reaction effect as the activity decreases during the reaction process, the recorded reaction temperature is the temperature interval of the highest temperature in the bed with the change of reaction time.

[0069] The above described embodiments only express the best mode of the present application, and the description is more specific and detailed, but it should not be understood as a limitation to the scope of the patent. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a gold nanoparticle core, characterized in that: Composed of nano-Au core and C-Cu-M x O y Composed of a @mSiO2 shell, with a nano-Au core diameter of 11nm~33nm, C-Cu-M x O y The thickness of the @mSiO2 shell is 55nm~75nm, the pore size is 2.1nm~3.2nm, and M is one or more of zinc, zirconium, cerium and nickel.

2. The catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a gold nanoparticle core according to claim 1, characterized in that: In this catalyst, the mass fraction of C is 1.3~3.3%, the mass fraction of Cu is 24.5~43.5%, and the mass fraction of M is... x O y The mass fraction is 1.8~4.2%, the mass fraction of Au is 0.18~0.67%, and the remainder is SiO2; among which, Cu exists in an electron-rich state. 0 With electron-deficient Cu + Two states exist, Cu + / (Cu + +Cu 0 The atomic ratio is 15%~28%.

3. The method for preparing a catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a gold nanoparticle core as described in claim 1, characterized in that, Includes the following steps: Step 1: Under strong stirring, mix the heated and boiled chloroauric acid aqueous solution with sodium citrate aqueous solution evenly, and continue boiling for 30 min to 60 min to obtain Au sol solution; Step 2: Prepare a mixture with a fixed alcohol / water ratio, and use it as a solvent to dissolve copper salt, organic ligand, metal auxiliary salt, and surfactant in it. Then, add precipitant and silicon source in sequence, stir evenly, and obtain copper salt mixed solution. Step 3: Add the Au sol solution prepared in Step 1 to the copper salt mixed solution prepared in Step 2, sonicate for 20 min to 50 min, heat under deuterium lamp irradiation at 80 to 110 °C for 3 to 10 h, then transfer to a hydrothermal reactor and heat to 120 to 180 °C for hydrothermal treatment for 5 to 10 h. Step 4: After the reaction is complete, the mixture is centrifuged and the resulting precipitate is washed with distilled water and ethanol 3 to 5 times to remove impurities. It is then dried at 80 to 110 °C for 10 to 16 h and calcined at 350 °C to 650 °C for 3 to 6 h to obtain catalyst powder. Step 5: Add carbon fiber, graphite powder, graphene, and organic carbon source to the catalyst powder obtained in Step 4, mix evenly, and then compress into tablets to obtain a tableted catalyst. Step Six: The tableted catalyst prepared in Step Five is loaded into an atmosphere furnace, and after passing through a H2 / N2 mixed gas, it is heated and reduced to finally obtain the catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with nano-Au particles as the core and SiO2 shell confinement.

4. The method for preparing a catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a gold nanoparticle core according to claim 3, characterized in that: In step one, the mass concentration of chloroauric acid in the chloroauric acid aqueous solution is 0.1 kg / m³. 3 ~ 0.2 Kg / m 3 The sodium citrate concentration in the aqueous solution is 2 kg / m³. 3 ~17 Kg / m 3 Sodium citrate aqueous solution and chloroauric acid aqueous solution were mixed at a volume ratio of 2:100 to 6:100 to obtain Au sol solution with Au nanoparticle size of 11 nm to 33 nm.

5. The method for preparing a catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a gold nanoparticle core according to claim 3, characterized in that: In step two, the solvent used is ethanol, and the water is distilled water, with a volume ratio of distilled water to ethanol of 1:10 to 5:

10. The copper salt is selected from one or both of copper nitrate trihydrate and copper nitrate hexahydrate, and the mass concentration of copper in the copper salt mixture is 2.5 kg / m³. 3 ~4.5 Kg / m 3 ; The organic ligand is selected from one or two of 3,5-pyrazole dicarboxylic acid and 1,10-phenanthroline, and the mass concentration of the organic ligand in the copper salt mixture is 0.0026 kg / m³. 3 ~0.0164 Kg / m 3 The metal additive salt is selected from one or more of zinc nitrate hexahydrate, zirconium nitrate pentahydrate, cerium nitrate hexahydrate, and nickel nitrate hexahydrate. The mass concentration of the metal additive in the copper salt mixture is determined by its oxide M. x O y The formal calculation yields 0.20 kg / m³. 3 ~0.6 Kg / m 3 The surfactant is selected from one or two of polyvinylpyrrolidone and hexadecyl ammonium bromide, and the mass concentration of the surfactant in the copper salt mixture is 2 kg / m³. 3 ~6 Kg / m 3 The precipitant was urea, and the mass concentration of urea in the copper salt mixture was 8.9 kg / m³. 3 ~16.5 Kg / m 3 The silicon source is selected from one or both of tetraethyl orthosilicate and silica sol. The mass concentration of the silicon source in the copper salt mixture is calculated as SiO2 and is 4.8 kg / m³. 3 ~7.3 Kg / m 3 .

6. The method for preparing a catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a gold nanoparticle core according to claim 3, characterized in that: In step three, the volume ratio of the copper salt mixed solution to the Au sol solution is 3:1.035 to 3:1.811; the wavelength of the deuterium lamp is 190 nm to 400 nm, and the power is 30 W.

7. The method for preparing a catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a gold nanoparticle core according to claim 3, characterized in that: In step four, the roasting temperature is 400℃~500℃.

8. The method for preparing a catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a gold nanoparticle core according to claim 3, characterized in that: In step five, carbon fiber, graphite powder, graphene, and organic carbon source account for 0.1%~0.3%, 1~3%, 0.1%~0.2%, and 5%~10% of the mass fraction of the catalyst powder, respectively; the organic carbon source is one or two of citric acid and sucrose; the resulting tableted catalyst is columnar with a height × diameter of 3mm×3mm, 4mm×4mm, or 5mm×5mm.

9. The method for preparing a catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with a gold nanoparticle core according to claim 3, characterized in that: In step six, the volume fraction of H2 in the H2 / N2 mixture is 0.5%~5%, the reduction temperature is 150℃~350℃, and the time is 1 h~12 h.

10. The application of the maleic anhydride hydrogenation catalyst with a gold nanoparticle core as described in claim 1 or 2, or the maleic anhydride hydrogenation catalyst with a gold nanoparticle core prepared by any one of claims 3-9, in the reaction of maleic anhydride and hydrogen to synthesize γ-butyrolactone.

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