A nano-silica-loaded nano-metal solid material, its preparation method, and its application in hydrogenation and dealdehyde treatment

Abstract

The nano-silica-loaded nano-metal solid material disclosed in the present invention is based on SiO2 microspheres, with weakly polar alkyl groups connected to the surface of the substrate, and nano-metal particles are loaded on the substrate as a carrier. The solid material is represented by the general formula m(Me)-SiO2-(R)n, wherein Me is one of Ag, Ru, and Ni, and R is the abbreviation of the alkyl group. The present invention uses the reverse microemulsion method as the preparation method, which is easy to operate and can synthesize a solid material with uniform size and stability. When the solid material of the present invention is used for hydrogenation dealdehydeation, on the one hand, it promotes the adsorption of aldehydes on the surface of the solid material, and on the other hand, it promotes the hydrogenation conversion of aldehydes, achieves the purpose of deep removal of aldehydes, and can reduce the concentration of aldehydes in ethanol to less than 0.1ppm. The new method for ethanol dealdehydeation innovatively proposed by the present invention is in line with the green chemistry concept advocated today, with low energy consumption, high degree of removal and good effect.

Description

Technical Field

[0001] The invention belongs to the technical field of raw material purification, and particularly relates to a nano-silicon dioxide-loaded nano-metal solid catalyst, a preparation method thereof, and a hydrogenation and dealdehyde application thereof. Background Art

[0002] Bioethanol is a fuel alcohol produced by microbial fermentation of various biomasses. Bioethanol can be used alone or blended with gasoline to create ethanol gasoline for automotive fuel. The use of bioethanol improves engine efficiency, helps reduce harmful emissions and pollutants, and combats climate change. Bioethanol will also drive more efficient internal combustion and hybrid engines. The alcohol we consume daily also comes from bioethanol. Formaldehydes, such as formaldehyde and acetaldehyde, are unavoidable byproducts of the bioethanol production process. During use, these aldehydes are transferred from the ethanol to the environment, causing varying degrees of negative impacts on humans and the natural environment. Due to their high carcinogenicity, aldehydes can also directly and significantly affect the human body after consuming alcoholic beverages. Currently, the removal of aldehydes from ethanol is primarily achieved through distillation, a process that consumes significant energy and is extremely challenging to reduce to below 10 ppm.

[0003] The solid catalytic method is another known method for removing aldehydes, but it has the following shortcomings: first, the removal effect is unstable and easily affected by reaction conditions such as temperature, pressure, and reactant concentration; second, the selectivity of aldehydes is not high, and they are easily partially oxidized by the action of the catalyst to produce harmful substances; third, the catalyst is deactivated, and the catalyst may be deactivated by factors such as the toxic effects of the reactants, high temperature, and high pressure. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a nano-silicon dioxide-loaded nano-metal solid material and its preparation method and hydrogenation dealdehyde application in view of the deficiencies in the prior art.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a solid material of nano-silica loaded with nano-metal, the solid material uses SiO2 microspheres as a substrate, weakly polar alkyl groups are connected to the surface of the substrate, and nano-metal particles are loaded on the substrate as a carrier. The solid material is represented by the general formula m(Me)-SiO2-(R)n, wherein Me is the abbreviation of the metal element, Me is one of Ag, Ru, and Ni, R is the abbreviation of the alkyl group, the alkyl group R is derived from organic silane, the SiO2 microspheres are derived from orthosilicate low-carbon alcohol ester, the organic silane and the orthosilicate low-carbon alcohol ester constitute the total silane, m is 100 times the molar ratio of the required metal element to the total silane, and n is 100 times the molar ratio of the required organic silane to the total silane.

[0006] Preferably, m=0.1-18, n=5-50.

[0007] Preferably, the particle size of the SiO2 microspheres is 30-120 nanometers, and the particle size of the nano-metal particles is less than 10 nanometers.

[0008] Preferably, the metal element Me is derived from a metal salt, wherein Ag is derived from silver acetate or silver nitrate, Ru is derived from ruthenium trichloride or ruthenium acetate, and Ni is derived from nickel acetate or nickel nitrate; the lower carbon alcohol orthosilicate is methyl orthosilicate or ethyl orthosilicate, and the organosilane is an alkyltriethoxysilane or alkyltrimethoxysilane containing one of the groups selected from methyl, ethyl, propyl, pentyl, phenyl, trifluoropropyl and N,N-diethyl.

[0009] The method for preparing the nano-silicon dioxide-loaded nano-metal solid material comprises the following steps:

[0010] 1) Mixing a surfactant, an organic phase, and a cosurfactant to prepare a reverse microemulsion A; mixing a metal salt with 25-28% ammonia water and deionized water to prepare a solution B;

[0011] 2) using orthosilicate lower alcohol ester and organosilane as silicon sources, mixing them to prepare solution C;

[0012] 3) mixing reverse microemulsion A and solution B to obtain reverse microemulsion D, adding solution C to solution D under stirring, and aging for 7-12 hours to obtain solution E, wherein solution E contains, in parts by mass, 4-8 parts of a surfactant, 1-4 parts of deionized water, 1-2 parts of aqueous ammonia, 3-9 parts of an organic phase, 2-6 parts of a cosurfactant, 1 part of a lower alcohol orthosilicate, 0.75-1.485 parts of an organosilane, and 0.015-0.75 parts of a metal salt;

[0013] 4) Adding acetone (5-10 times the mass of the lower alcohol orthosilicate used in step 2) to solution E to break the emulsion, and collecting the solid by centrifugation; then washing the solid with ethanol 2-6 times to remove residual surfactant, and then drying at room temperature to obtain a granular nanomaterial, i.e., a nano-silica-loaded nano-metal solid material.

[0014] Preferably, the surfactant is a long-chain nonionic surfactant, the organic phase is a low-carbon alkane with 5-8 carbon atoms, and the co-surfactant is a low-carbon amine compound.

[0015] Preferably, the surfactant is an organic primary amine, an Np series surfactant or a Tween series surfactant, the organic phase is cyclohexane, n-hexane or n-heptane, and the co-surfactant is n-butylamine or n-propylamine.

[0016] The hydrogenation and dealdehydeation of the nano-silica-loaded nano-metal solid material is applied to the catalytic hydrogenation deep removal process of aldehydes in ethanol.

[0017] Preferably, when m=3-6 and n=20-30, the best catalytic performance is obtained when it is applied to the deep removal of aldehydes in ethanol by catalytic hydrogenation.

[0018] Preferably, the substrate for the hydrogenation reaction is a small molecule aldehyde (such as formaldehyde, acetaldehyde, etc.), the hydrogen source is high-pressure hydrogen, the hydrogenation reaction temperature is 25-120°C, with an optimum temperature of 70-90°C, and the reaction time is 30-480 minutes, with an optimum time of 60-240 minutes. After the hydrogenation reaction, the residual aldehyde content in the ethanol is less than 0.1 ppm. These relatively mild hydrogenation reaction conditions result in a substrate conversion rate of 90-99%, resulting in excellent aldehyde impurity removal.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The solid material of the present invention uses nanometals as catalytically active centers and alkyl groups as modifying groups. By regulating the ratio of alkyl groups to silanol groups on the silica surface, the resulting super-hydrophobic surface can promote the preferential adsorption of low-concentration aldehydes in ethanol, promoting the conversion of aldehydes, thereby obtaining high-purity raw materials and reducing the harmful effects of aldehydes. Because the solid material of the present invention exhibits strong adsorption and conversion capabilities for aldehydes in ethanol, the concentration of aldehydes in ethanol can be reduced to below 0.1 ppm.

[0021] 2. The present invention uses the reverse microemulsion method as the preparation method, which is simple to operate and can synthesize nano-silica-loaded nano-metal solid materials that are uniform in size, stable, and have alkyl groups modified on the surface.

[0022] 3. When the solid material of the present invention is used for hydrogenation and dealdehydeation, on the one hand, it promotes the adsorption of aldehydes on the surface of the solid material, and on the other hand, it promotes the hydrogenation conversion of aldehydes, thereby achieving the purpose of deep removal of aldehydes.

[0023] 4. This invention innovatively proposes a new method for ethanol dealdehyde removal—catalytic hydrogenation for deep dealdehyde removal. This method essentially involves solid-state catalytic hydrogenation of acetaldehyde to ethanol. This method reduces the content of aldehyde impurities in ethanol through a catalytic reaction, achieving deep purification of the ethanol. This method aligns with current green chemistry principles, offering low energy consumption, high levels of dealdehyde removal, and excellent results. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the SEM image of material A in Example 1;

[0025] Figure 2This is the TEM image of material A in Example 1. DETAILED DESCRIPTION

[0026] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0027] Example 1: Preparation of Material A (6Ag-SiO2-Ph2O)

[0028] Take 15g of nonylphenol polyoxyethylene ether, 35.1g of cyclohexane and 8g of n-butylamine and mix them to obtain reverse microemulsion A; 0.25g of silver acetate, 5.3g of deionized water and 2g of ammonia water are added to obtain solution B; 5.2g of ethyl orthosilicate and 1.2g of phenyltriethoxysilane are mixed to obtain solution C; solution B is poured into reverse microemulsion A to obtain solution D, and solution C is added to solution D under vigorous stirring and aged for 9h; then, 10mL of acetone is added, stirred for 30min, and centrifuged to obtain a white solid; 30mL of ethanol is added to the solid, heated and stirred for 17min, and centrifuged; this step is repeated many times until the surfactant is completely removed; dried at room temperature to obtain the final nano-silica-loaded nano-metal solid material 6Ag-SiO2-Ph20.

[0029] The SEM image of material A is shown in Figure 1 , TEM image see Figure 2 .from Figure 1 and Figure 2 It can be seen that the particle size of SiO2 microspheres is about 30nm, and nano-metal particles are evenly distributed on the surface of the microspheres.

[0030] Example 2: Preparation of Material BL

[0031] Material BL was prepared using the same method as Material A, differing in the types and ratios of the metal elements and alkyl groups. Furthermore, after hydrolysis of silver acetate and ruthenium trichloride, 0.2g of sodium borohydride or potassium borohydride was added for reduction. The specific types of metal salts and organosilanes used are listed in Table 1. The resulting solid materials are also listed in Table 1.

[0032] Table 1 Metal salts and organosilanes used in the preparation of material BL

[0033]

[0034] Example 3: Catalytic aldehyde hydrogenation reaction of material A

[0035] 0.03g of 6Ag-SiO2-Ph2O solid material was added to a reactor, followed by 10mL of an ethanol solution containing 100ppm of acetaldehyde. The stirring device was activated and the reaction was carried out at 90°C and 3MPa of hydrogen. After 480 minutes, the reaction was stopped. After cooling, a portion of the reactants was removed and acetaldehyde was quantitatively analyzed using a gas chromatograph with an internal standard method. The acetaldehyde conversion rate was calculated based on the changes in the reactants before and after the reaction. The specific aldehyde impurity concentrations in the reactants, reaction conditions, and reaction results are shown in Table 2.

[0036] Example 4: Reaction results of catalytic condensation reactions of different solid materials

[0037] The solid material used was material BL. The activity evaluation method of the solid material was the same as that in Example 3, and both were analyzed by internal standard gas chromatography. The specific aldehyde impurity concentrations contained in the reactants, reaction conditions, and reaction results are shown in Table 2.

[0038] As can be seen from Table 2, after the solid material of the present invention is used for hydrodesaldaldehyde treatment, the conversion rate of aldehyde impurities is 90-99%, achieving an excellent removal rate of aldehyde impurities.

[0039] Table 2 Reaction results of catalytic condensation reaction of different solid catalysts

[0040]

[0041]

Claims

1. A nano-silicon dioxide-loaded nano-metal solid material, characterized in that: The solid material uses SiO2 microspheres as a substrate, has weakly polar alkyl groups connected to the surface of the substrate, and is loaded with nano-metal particles using the substrate as a carrier. The solid material is represented by the general formula m(Me)-SiO2-(R)n, wherein Me is the abbreviation of the metal element, Me is Ag, and R is the abbreviation of the alkyl group. The alkyl group R is derived from organic silane, the SiO2 microspheres are derived from orthosilicate lower carbon alcohol ester, the organic silane and the orthosilicate lower carbon alcohol ester constitute the total silane, m is 100 times the molar ratio of the required metal element to the total silane, and n is 100 times the molar ratio of the required organic silane to the total silane. The preparation method of the solid material comprises the following steps: 1) The surfactant, organic phase, and cosurfactant are mixed to prepare reverse microemulsion A; the metal salt is mixed with 25-28% ammonia water and deionized water to prepare solution B; 2) Using lower alcohol orthosilicate and organosilane as silicon sources, mix them to prepare solution C; 3) Mixing reverse microemulsion A and solution B to obtain reverse microemulsion D, adding solution C to solution D under stirring, and aging for 7-12 hours to obtain solution E, wherein solution E contains, in parts by mass, the following: 4-8 parts of surfactant, 1-4 parts of deionized water, 1-2 parts of aqueous ammonia, 3-9 parts of organic phase, 2-6 parts of co-surfactant, 1 part of lower alcohol orthosilicate, 0.75-1.485 parts of organosilane, and 0.015-0.75 parts of metal salt; 4) Adding acetone (5-10 times the mass of the lower alcohol orthosilicate used in step 2) to solution E to break the emulsion, and collecting the solid by centrifugation; then washing the solid with ethanol 2-6 times, and then drying at room temperature to obtain a granular nanomaterial, i.e., a nano-silica-loaded nano-metal solid material; The surfactant is a long-chain nonionic surfactant, the organic phase is a low-carbon alkane with 5 to 8 carbon atoms, and the co-surfactant is a low-carbon amine compound.

2. The nano-silicon dioxide-loaded nano-metal solid material according to claim 1, characterized in that: m=0.1-18, n=5-50.

3. The nano-silicon dioxide-loaded nano-metal solid material according to claim 1, characterized in that: The particle size of the SiO2 microspheres is 30-120 nanometers, and the particle size of the nano metal particles is less than 10 nanometers.

4. The nano-silicon dioxide-loaded nano-metal solid material according to claim 1, characterized in that: The metal element Me is derived from a metal salt, wherein Ag is derived from silver acetate or silver nitrate; the lower carbon alcohol orthosilicate is methyl orthosilicate or ethyl orthosilicate, and the organosilane is an alkyltriethoxysilane or alkyltrimethoxysilane containing one of methyl, ethyl, propyl, pentyl, phenyl, trifluoropropyl and N, N-diethyl groups.

5. The nano-silicon dioxide-loaded nano-metal solid material according to claim 1, characterized in that: The surfactant is an organic primary amine, an Np series surfactant or a Tween series surfactant, the organic phase is cyclohexane, n-hexane or n-heptane, and the co-surfactant is n-butylamine or n-propylamine.

6. Application of the nano-silica-loaded nano-metal solid material according to any one of claims 1 to 4 in the hydrodesaldaldehyde removal process of aldehydes in ethanol by catalytic hydrogenation.

7. The application of hydrodesaldaldehyde according to claim 6, characterized in that: When m=3-6 and n=20-30, the best catalytic performance is obtained when it is applied to the deep removal of aldehydes in ethanol by catalytic hydrogenation.

8. The application of hydrodesaldaldehyde according to claim 6, characterized in that: The substrate of hydrogenation reaction is small molecular aldehydes, the hydrogen source is high pressure hydrogen, and the temperature of hydrogenation reaction is 25-120 o C, the reaction time is 30-480 minutes, and after the hydrogenation reaction, the residual amount of aldehydes in ethanol is less than 0.1 ppm.

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