Gamma-butyrolactone catalyst prepared by hydrogenation of maleic anhydride with nanogold as core, preparation method and application of gamma-butyrolactone catalyst

Abstract

The invention discloses a gamma-butyrolactone catalyst prepared by maleic anhydride hydrogenation with nanogold as an inner core, and a preparation method and application thereof, and belongs to the technical field of core-shell structure catalysts. The catalyst disclosed by the invention is composed of a nano Au core and a C-Cu-MxOy (at) mSiO2 shell layer, and the aperture of the catalyst is 2.1 nm to 3.2 nm. The preparation method of the catalyst comprises the following steps: preparing an Au sol solution, preparing a copper salt mixed solution containing an organic ligand, a metal auxiliary agent salt, a surfactant, a precipitator and a silicon source, adding the Au sol solution into the copper salt mixed solution to obtain catalyst powder, tabletting the catalyst powder, carrying out heating reduction on the tabletted catalyst, and carrying out vacuum drying to obtain the catalyst. And finally, the gamma-butyrolactone catalyst prepared by hydrogenation of C-Cu-MxOy maleic anhydride, which takes nano Au particles as an inner core and is limited by a SiO2 shell layer, is obtained. Based on a plurality of structural advantages, the catalyst disclosed by the invention shows excellent activity, selectivity and use stability in maleic anhydride hydrogenation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of core-shell structure catalysts, and particularly relates to a catalyst for preparing gamma-butyrolactone by hydrogenation of maleic anhydride, 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, etc. 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, etc. 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 pharmaceutical field, such as ciprofloxacin, cerebrolysin, vitamin B, tranquilizer gamma-hydroxybutyric acid, acetylcholinesterase inhibitor, etc. With the rapid development of China's economy, especially the development of industries such as lithium ion batteries, the demand for GBL in China is increasing year by year.

[0003] Compared with the two routes of preparing GBL by dehydrogenation of 1,4-butanediol (BDO) and by esterification and hydrogenation of maleic anhydride, the direct hydrogenation of maleic anhydride to synthesize GBL has the advantages of short process flow, large 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, US5122485, CN1058400A, CN1111167A], and Ba, Pd, Pt, etc. 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, short service life, etc. still 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 production of high polymers, causing the catalyst to be deactivated by carbon deposition. SUMMARY

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

[0006] The present application is realized by the following technical solutions: According to a first aspect of the present application, a catalyst for preparing gamma-butyrolactone by hydrogenation of maleic anhydride with nano-gold as the inner core is provided, which comprises a nano-Au inner core and a C-Cu-Mx O y The diameter of the Au core is 11 nm-33 nm, the thickness of the @mSiO2 shell is 55 nm-75 nm, and the pore size is 2.1 nm-3.2 nm. x O y The diameter of the Au core is 11 nm-33 nm, the thickness of the @mSiO2 shell is 55 nm-75 nm, and the pore size is 2.1 nm-3.2 nm.

[0007] 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 Au is 0.18-0.67 %, and the rest is SiO2. x O y 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 Au is 0.18-0.67 %, and the rest is SiO2. 0 The Cu exists in the form of Cu and Cu. + The Cu exists in the form of Cu and Cu. + The atomic ratio of Cu to Cu is 15 %-28 %. + The atomic ratio of Cu to Cu is 15 %-28 %. 0

[0008] According to a second aspect of the present application, a preparation method of the above-mentioned catalyst for hydrogenation of maleic anhydride to γ-butyrolactone with gold as a core is provided, and the method comprises the following steps: Step one: uniformly mix the heated and boiled aqueous solution of chloroauric acid with the aqueous solution of sodium citrate under strong stirring, and continue to boil for 30 min-60 min to obtain an Au sol solution.

[0009] 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 a solvent, and then add the precipitant and silicon source in sequence, and uniformly stir to obtain a copper salt mixed solution.

[0010] 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 and reflux at 80-110 ℃ under the irradiation of a deuterium lamp for 3-10 h, then transfer to a hydrothermal kettle, and heat to 120-180 ℃ for hydrothermal treatment for 5-10 h.

[0011] 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.

[0012] Step five: add carbon fibers, graphite powder, graphene and an organic carbon source to the catalyst powder obtained in step four, uniformly mix, and then press and form into tablets to obtain a tablet-shaped catalyst. ​

[0013] Step six: the tablet-shaped catalyst prepared in step five is loaded into a gas atmosphere furnace, and after H2 / N2 mixed gas is introduced, the temperature is raised for reduction, and finally the catalyst for hydrogenation of maleic anhydride to γ-butyrolactone with nano gold as the core and the nano gold particle as the core and the SiO2 shell as the confinement is obtained.

[0014] 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 at a volume ratio of 2:100~6:100, and the size of the Au nano particle in the obtained Au sol solution is 11 nm~33 nm.

[0015] 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 , and 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, and is 4.8 Kg / m 3 ~7.3 Kg / m 3 .

[0016] 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.

[0017] Further, in step four, the calcination temperature is 400℃~500℃.

[0018] Further, in step five, the mass fraction of the carbon fiber, the graphite powder, the graphene and the 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; and 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.

[0019] 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.

[0020] 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.

[0021] The catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with the nano gold as the core prepared by the present application is applied to the heterogeneous system of the gas phase normal pressure hydrogenation of maleic anhydride to γ-butyrolactone, specifically, the hydrogen and the maleic anhydride steam are mixed, and then the gas phase materials are reacted through the fixed bed reactor filled with the catalyst, wherein the reaction temperature of the reactor 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%.

[0022] The catalyst for the hydrogenation of maleic anhydride to γ-butyrolactone with the nano gold as the core and the preparation method have the following advantages compared with the existing catalysts: (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.

[0023] (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.

[0024] (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.

[0025] (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. 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. 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.

[0026] (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 mesoporous mSiO2 shell layer plays an important role. First, it limits the Cu and other metal additives in the SiO2 shell layer, which plays a role in inhibiting the aggregation of active components. Second, the mesoporous channels can act as reaction channels to strengthen the mass transfer and heat transfer of reactants and accelerate the reaction rate.

[0027] (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

[0028] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate exemplary embodiments of the application and, together with the general description given above and the detailed description given below, serve to explain the application, but are not intended to limit the application unduly.

[0029] Figure 1 A high-resolution electron microscope photograph of the catalyst for preparing gamma-butyrolactone from maleic anhydride with nanometer gold as the core according to the present application. DETAILED DESCRIPTION

[0030] The present application provides a catalyst for preparing gamma-butyrolactone from maleic anhydride with nanometer gold as the core, which comprises a nanometer Au core and a C-Cu-M x O y@mSiO2 shell composition, the diameter of the nano-Au core is 11nm~33nm, C-Cu-M x O y The thickness of the @mSiO2 shell is 55nm~75nm, and the pore size is 2.1nm~3.2nm. 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 x O y The mass fraction is 1.8~4.2%, the mass fraction of Au is 0.18~0.67%, and the rest is SiO2. 0 With electron-deficient Cu + There are two states, Cu + / (Cu + +Cu 0 ) atomic ratio is 15%~28%.

[0031] The present invention also provides a method for preparing the catalyst for hydrogenating maleic anhydride to γ-butyrolactone using nano-gold as a core, comprising the following steps: Step 1: Mix the heated and boiled chloroauric acid aqueous solution and sodium citrate aqueous solution evenly under strong stirring conditions, and continue boiling for 30 min to 60 min to obtain an Au sol solution.

[0032] 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 to 6:100, and the Au nanoparticles in the obtained Au sol solution have a size of 11 nm to 33 nm, preferably 13 nm to 26 nm.

[0033] Step 2: Prepare a mixed solution with a fixed alcohol / water ratio, and use it as a solvent to dissolve copper salt, organic ligand, metal additive salt, and surfactant in it, and then add a precipitant and a silicon source in sequence, stir evenly, and obtain a copper salt mixed solution.

[0034] In this step, the volume ratio of distilled water to ethanol in the prepared solvent is 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 / m 3 ~4.5 Kg / m 3 The organic ligand is selected from one or both of 3,5-pyrazoledicarboxylic acid and 1,10-phenanthroline, and the mass concentration of the organic ligand in the copper salt mixture is 0.0026 Kg / m3 ~0.0164 Kg / m 3 Metal additive salt is selected from zinc nitrate hexahydrate, zirconium nitrate pentahydrate, cerium nitrate hexahydrate, nickel nitrate hexahydrate, one or more, the mass concentration of the metal additive in the copper salt mixture is the oxide M x O y Calculated in the form of 0.20 Kg / m 3 ~0.6 Kg / m 3 The surfactant is selected from one or both of polyvinyl pyrrolidone and hexadecyl ammonium bromide, and the mass concentration of the surfactant in the copper salt mixture is 2 Kg / m 3 ~6 Kg / m 3 The precipitant is urea, and the mass concentration of urea in the copper salt mixture is 8.9 Kg / m 3 ~16.5 Kg / m 3 The silicon source is selected from one or both of ethyl orthosilicate and silica sol. The mass concentration of the silicon source in the copper salt mixture is calculated as SiO2, which is 4.8 Kg / m 3 ~7.3 Kg / m 3 .

[0035] Step 3: Add the Au sol solution prepared in step 1 to the copper salt mixed solution prepared in step 2, ultrasonically treat for 20 min~50 min, heat and reflux at 80~110 °C under deuterium lamp for 3~10 h, then transfer to a hydrothermal reactor, heat to 120~180 °C and hydrothermally treat for 5~10 h.

[0036] In this step, 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.

[0037] Step 4: After the reaction is completed, the mixed solution is centrifuged and the resulting precipitate is washed with distilled water and ethanol 3 to 5 times to remove impurities, 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.

[0038] In this step, the calcination temperature is 400°C to 500°C.

[0039] Step 5: Add carbon fiber, graphite powder, graphene, and an organic carbon source to the catalyst powder obtained in step 4, mix well, and then press into tablets to obtain a tablet-shaped catalyst.

[0040] In this step, the mass fractions of carbon fiber, graphite powder, graphene and organic carbon source in the catalyst powder are 0.1%~0.3%, 1~3%, 0.1%~0.2% and 5%~10%, respectively; the organic carbon source is one or two of citric acid and sucrose; the obtained pressed tablet catalyst is columnar, with a height × diameter specification of 3mm×3mm, 4mm×4mm or 5mm×5mm.

[0041] Step 6: The pressed catalyst prepared in step 5 is placed in an atmosphere furnace, and after the H2 / N2 mixed gas is introduced, the temperature is increased for reduction, and finally the nano-gold-based maleic anhydride hydrogenation to γ-butyrolactone catalyst with nano-Au particles as the core and SiO2 shell as the confinement is obtained.

[0042] In this step, the volume fraction of H2 in the H2 / N2 mixed gas is 0.5% to 5%, the reduction temperature is 150°C to 350°C, and the time is 1 h to 12 h, preferably 3 h to 8 h.

[0043] The present invention also provides the use of the maleic anhydride hydrogenation catalyst with nano-gold as the core to produce γ-butyrolactone or the maleic anhydride hydrogenation catalyst with nano-gold as the core prepared by the above preparation method in the reaction of maleic anhydride and hydrogen to synthesize γ-butyrolactone.

[0044] Furthermore, in order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further clearly and completely described below in conjunction with the accompanying drawings and in conjunction with specific embodiments. It should be noted that, unless there is a conflict, the features in the embodiments and examples in this application can be combined with each other. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. Example 1

[0045] Preparation of Au sol solutions with different Au nanoparticle sizes. As shown in Table 1, 0.2-0.4 kg of chloroauric acid was weighed and dissolved in deionized water to a volume of 2 m 3 , the mass concentration of chloroauric acid is 0.1~0.2 Kg / m 3 chloroauric acid solution and heat to boiling; weigh 0.4~3.4 Kg of sodium citrate and dissolve it in deionized water and adjust the volume to 200 L to obtain a sodium citrate mass concentration of 2~17 Kg / m 3 Take 40~120 L of sodium citrate solution, heat it to boiling, and add it to 2 m 3 The Au sol solution with Au nanoparticles of 11 to 33 nm in size was obtained by boiling the chloroauric acid aqueous solution for 30 to 60 minutes. Table 1 Preparation conditions of Au sol solutions with different particle sizes Example 2

[0046] Prepare a copper salt mixed solution according to the amounts of components listed in Table 2. Weigh the required mass of copper nitrate trihydrate and / or copper nitrate hexahydrate, the required mass of organic ligand 3,5-pyrazoledicarboxylic acid and / or 1,10-phenanthroline, add 2 ml of alcohol-water mixed solution with a volume ratio of distilled water to ethanol of 1:10 to 5:10, and stir. 3 , stirring to dissolve; then weigh the required mass of one or more of zinc nitrate hexahydrate, zirconium nitrate pentahydrate, cerium nitrate hexahydrate, 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), the required mass of urea, and add them in turn to the alcohol aqueous solution dissolved in the copper salt and the organic ligand, dissolve under stirring, and continue to add the alcohol aqueous solution with a volume ratio of distilled water to ethanol of 1:10 to 5:10 to make the volume 3 m 3 , to obtain a copper salt mixed solution. The mass concentration of copper in the copper salt mixed solution is controlled at 2.5 Kg / m 3 ~4.5 Kg / m 3 The mass concentration of organic ligand is controlled at 0.0026 Kg / m 3 ~0.0164 Kg / m 3 , the mass concentration of the metal additive, its oxide M x O y Form calculation, at 0.20 Kg / m 3 ~0.60 Kg / m 3 The mass concentration of the silicon source reagent is calculated as SiO2, which is 4.8 Kg / m 3 -7.3 Kg / m 3 The concentration of surfactant is controlled at 2Kg / m 3 ~6 Kg / m 3 The mass concentration of urea in the copper salt mixture is 8.9 Kg / m 3 ~16.5 Kg / m 3 ; Table 2 Wet chemical process

[0047] The Au sol solution prepared in Example 1 was added to the copper salt mixed solution. The volume ratio of the copper salt mixed solution to the gold sol solution was 3:1.035~3:1.811. Ultrasonic treatment was performed for 20 min~50 min. Under the irradiation of a deuterium lamp with a wavelength of 190 nm~400 nm and a power of 30 W, the mixture was heated to reflux at 80~110 °C for 3~10 h. The mixture was then transferred to a hydrothermal reactor and heated to 120~180 °C for hydrothermal treatment for 5~10 h. After the reaction was completed, the mixed solution was centrifuged and the resulting precipitate was washed with distilled water and ethanol for 3~5 times to remove impurities. The mixture was dried at 80~110 °C for 10~16 h and then calcined at 350°C~650 °C for 3 h~6 h to obtain a catalyst powder. The preferred calcination conditions are 400°C~500°C, as shown in Table 3. Table 3 Precipitation process Example 3

[0048] Weigh 100 kg of the catalyst powder prepared in Example 2, add carbon fiber, graphite powder, graphene, and an organic carbon source according to the specific conditions listed in Table 4, mix well, and press into tablets. The mass fractions of carbon fiber, graphite powder, graphene, and the organic carbon source in the catalyst powder are 0.1% to 0.3%, 1 to 3%, 0.1% to 0.2%, and 5% to 10%, respectively. The organic carbon source is citric acid and / or sucrose. After tableting, the obtained tablet-shaped catalyst is in the form of a column with a height × diameter specification of 3 mm × 3 mm, 4 mm × 4 mm, or 5 mm × 5 mm; Table 4 Molding conditions Example 4

[0049] The prepared catalysts were characterized by high-resolution electron microscopy. Figure 1 As shown, it can be seen that a Au core is formed and a C-Cu-M coating is formed on the outside. x O y The prepared catalyst was reduced with H2 and its composition and physicochemical properties were determined, 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 rest is SiO2. x O y The thickness of the @mSiO2 shell is 55 nm~75 nm, and the average pore size is 2.1 nm~3.2 nm. 0 With electron-deficient Cu+ Two states exist, Cu + / (Cu + +Cu 0 ) atomic ratio is 15%~28%, the electronic state of Cu species and atomic ratio are determined by X-ray excited Auger electron spectroscopy; Table 5 Composition and physical properties

[0050] Note: Cu and metal oxide content is determined by ICP-AES technology; C mass fraction is determined by elemental analysis; shell thickness and Au particle size is obtained by high-resolution electron microscopy combined with particle statistics. Example 5

[0051] The performance of the catalyst 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), the temperature was raised to 150-350°C at a rate of 0.5-5°C / min in a H2 / N2 mixed gas with a H2 volume fraction of 0.5-5% by electric heating control, and reduced for 1-12 h. The reaction temperature was adjusted to 250°C, 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°C without further increasing the temperature to complete a reaction cycle. After regeneration, the catalyst was re-fed into the next reaction cycle; Table 6 Reduction and evaluation results of various catalysts

[0052] 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 interval of the highest temperature in the bed with the change of reaction time.

[0053] The above-described embodiments only express the most optimal implementation of the present application, which is described in more detail and specifically, but it should not be understood as a limitation on the scope of the present patent. It should be noted that for ordinary skilled persons 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 the present application.

Claims

1. A nano-gold core catalyst for hydrogenating maleic anhydride to produce γ-butyrolactone, characterized in that: Composed of nano-Au core and C-Cu-M x O y @mSiO2 shell composition, the diameter of the nano-Au core is 11nm~33nm, C-Cu-M x O y @mSiO2 shell thickness is 55nm~75nm, and pore diameter is 2.1nm~3.2nm.

2. The catalyst for hydrogenating maleic anhydride to produce gamma-butyrolactone with nano-gold as the core according to claim 1, wherein: 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 is 1.8~4.2%, the mass fraction of Au is 0.18~0.67%, and the rest is SiO2; among them, Cu is in the form of electron-rich Cu 0 With electron-deficient Cu + There are two states, Cu + / (Cu + +Cu 0 ) atomic ratio is 15%~28%.

3. The method for preparing a catalyst for hydrogenating maleic anhydride to gamma-butyrolactone with nano-gold as the core according to claim 1, wherein: The steps include: Step 1: Mix the heated and boiled chloroauric acid aqueous solution and sodium citrate aqueous solution evenly under strong stirring conditions, and continue boiling for 30 min to 60 min to obtain an Au sol solution; Step 2: Prepare a mixed solution with a fixed alcohol / water ratio, and use it as a solvent to dissolve copper salt, organic ligand, metal additive salt, and surfactant in it, and then add a precipitant and a silicon source in sequence, stir evenly, and obtain a 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, ultrasonicate for 20 min~50 min, reflux at 80~110 °C under deuterium lamp for 3~10 h, then transfer to a hydrothermal reactor, heat to 120~180 °C and hydrothermally treat for 5~10 h; Step 4: After the reaction is completed, the mixed solution is centrifuged and the resulting precipitate is washed with distilled water and ethanol 3 to 5 times to remove impurities, 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 a catalyst powder; Step 5: adding carbon fiber, graphite powder, graphene, and an organic carbon source to the catalyst powder obtained in step 4, mixing them evenly, and then pressing them into tablets to obtain a tablet-shaped catalyst; Step 6: The pressed catalyst prepared in step 5 is placed in an atmosphere furnace, and after the H2 / N2 mixed gas is introduced, the temperature is increased for reduction, and finally the nano-gold-based maleic anhydride hydrogenation to γ-butyrolactone catalyst with nano-Au particles as the core and SiO2 shell as the confinement is obtained.

4. The method for preparing a catalyst for hydrogenating maleic anhydride to gamma-butyrolactone with nano-gold as the core according to claim 3, wherein: In step 1, 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 Sodium citrate aqueous solution and chloroauric acid aqueous solution are mixed in a volume ratio of 2:100~6:100, and the Au nanoparticle size in the obtained Au sol solution is 11 nm~33 nm.

5. The method for preparing a catalyst for hydrogenating maleic anhydride to gamma-butyrolactone with nano-gold as the core according to claim 3, wherein: In step 2, the prepared solvent is ethanol and water is distilled water, with a volume ratio of distilled water to ethanol of 1:10 to 5:10; the copper salt is 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 / m 3 ~4.5 Kg / m 3 ; The organic ligand is selected from one or both of 3,5-pyrazoledicarboxylic acid and 1,10-phenanthroline, and the mass concentration of the organic ligand in the copper salt mixture is 0.0026 Kg / m 3 ~0.0164 Kg / m 3 Metal additive salt is selected from zinc nitrate hexahydrate, zirconium nitrate pentahydrate, cerium nitrate hexahydrate, nickel nitrate hexahydrate, one or more, the mass concentration of the metal additive in the copper salt mixture is the oxide M x O y Calculated in the form of 0.20 Kg / m 3 ~0.6 Kg / m 3 The surfactant is selected from one or both of polyvinyl pyrrolidone and hexadecyl ammonium bromide, and the mass concentration of the surfactant in the copper salt mixture is 2 Kg / m 3 ~6 Kg / m 3 The precipitant is urea, and the mass concentration of urea in the copper salt mixture is 8.9 Kg / m 3 ~16.5 Kg / m 3 The silicon source is selected from one or both of ethyl orthosilicate and silica sol. The mass concentration of the silicon source in the copper salt mixture is calculated as SiO2, which is 4.8 Kg / m 3 ~7.3 Kg / m 3 .

6. The method for preparing a catalyst for hydrogenating maleic anhydride to gamma-butyrolactone with nano-gold as the core according to claim 3, wherein: In step 3, 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.

7. The method for preparing a catalyst for hydrogenating maleic anhydride to gamma-butyrolactone with nano-gold as the core according to claim 3, characterized in that: In step 4, the calcination temperature is 400°C to 500°C.

8. The method for preparing a catalyst for hydrogenating maleic anhydride to gamma-butyrolactone with nano-gold as the core according to claim 3, characterized in that: In step five, the mass fractions of carbon fiber, graphite powder, graphene and organic carbon source in the catalyst powder are 0.1%~0.3%, 1~3%, 0.1%~0.2% and 5%~10%, respectively; the organic carbon source is one or two of citric acid and sucrose; the obtained pressed tablet catalyst is columnar, with a height × diameter specification of 3mm×3mm, 4mm×4mm or 5mm×5mm.

9. The method for preparing a catalyst for hydrogenating maleic anhydride to gamma-butyrolactone with nano-gold as the core according to claim 3, wherein: In step six, the H2 volume fraction in the H2 / N2 mixture is 0.5% to 5%, the reduction temperature is 150°C to 350°C, and the time is 1 h to 12 h.

10. Use of the catalyst for hydrogenating maleic anhydride to produce γ-butyrolactone with nano-gold as the core according to claim 1 or 2, or the catalyst for hydrogenating maleic anhydride to produce γ-butyrolactone with nano-gold as the core prepared by the preparation method according to any one of claims 3 to 9, in the reaction of maleic anhydride and hydrogen to synthesize γ-butyrolactone.

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