A hydrophobic ordered mesoporous SBA-15 solid acid and its preparation method and application in heterogeneous catalysis

Abstract

The present invention belongs to the field of solid acid catalyst and catalytic technology, and is specifically related to a hydrophobic ordered mesoporous SBA 15 solid acid and its preparation method and application in homogeneous catalysis. The present invention mixes an organic template, an organosilicon source, an inorganic strong acid aqueous solution, phosphotungstic acid and a first organosilane, performs a hydrothermal reaction, and the obtained hydrophobic ordered mesoporous SBA 15 precursor is calcined, the obtained hydrophobic SBA 15 molecular sieve is mixed with a second organosilane and an organic solvent, and the obtained hydrophobic SBA 15 molecular sieve modified by sulfhydryl grafting is subjected to sulfhydryl oxidation reaction. The hydrophobic ordered mesoporous SBA 15 solid acid prepared by the present invention not only shows excellent catalytic performance in catalyzing biomass raw materials to prepare 5 hydroxymethylfurfural, but also by suppressing the diffusion of water molecules in the reaction solvent and water molecules generated during the reaction process into the molecular sieve pores, it is possible to effectively prevent water molecules from participating in the reaction process and thus causing side reactions.

Description

Technical Field

[0001] The invention belongs to the field of solid acid catalysts and catalytic technology, and specifically relates to a hydrophobic ordered mesoporous SBA-15 solid acid and a preparation method thereof and application thereof in heterogeneous catalysis. Background Art

[0002] As an important platform compound, the preparation of 5-hydroxymethylfurfural is of great significance for the utilization of biomass resources. In order to realize the conversion of biomass resources into 5-hydroxymethylfurfural, the design and selection of the catalytic system, including the reaction catalyst and the reaction solvent, are crucial. Usually, 5-hydroxymethylfurfural is prepared by homogeneous catalysis of inorganic acid in an aqueous solvent from biomass materials such as cellulose and glucose. However, a large number of hydrogen protons will be produced under aqueous conditions, resulting in more side reactions, and 5-hydroxymethylfurfural will continue to dehydrate to form by-products such as levulinic acid, formic acid, and humus. In addition, water is a typical by-product of acid-catalyzed reactions, which will be adsorbed on the surface of solid acid catalysts, resulting in the inactivation of some acid sites and even the hydrolysis of the solid acid catalyst skeleton. Therefore, it is necessary to develop a suitable catalytic system to improve the reaction selectivity and the yield of the target product. In order to overcome the drawbacks of the single-phase aqueous solvent system, researchers have continuously developed a biphasic solvent system and a solid acid catalyst. Among them, the biphasic solvent system takes the water / organic solvent biphasic solvent system as an example, the aqueous solvent is used as the reaction phase, and the biomass raw material is converted into 5-hydroxymethylfurfural by the action of the catalyst. The organic solvent is used as an extraction phase to continuously extract the 5-hydroxymethylfurfural generated by the reaction into the organic solvent, thereby effectively preventing the 5-hydroxymethylfurfural from continuing to react.

[0003] The ideal solid acid catalyst needs to have abundant and adjustable catalytic sites, suitable acidity and acid strength, as well as a large surface area and pore structure. These properties enable the solid acid catalyst to achieve full contact with the reaction substrate and also facilitate the diffusion of the reaction substrate and intermediate products. SBA-15 zeolite has a two-dimensional hexagonal highly ordered mesoporous structure and contains abundant Si-OH active groups on its surface. It is often used as a catalyst carrier and is widely used in catalysis, adsorption, separation and other fields.

[0004] At present, in order to increase the acid concentration of SBA-15 zeolite solid acid and thus improve its catalytic activity, it is reported in the literature that SBA-15 zeolite solid acid is modified with acidic groups such as sulfonate groups, but this will significantly reduce the hydrophobicity of SBA-15 zeolite, resulting in excessive side reactions. Summary of the invention

[0005] The purpose of the present invention is to provide a hydrophobic ordered mesoporous SBA-15 solid acid and a preparation method thereof and an application thereof in catalyzing the reaction of generating 5-hydroxymethylfurfural from biomass resources. When the hydrophobic ordered mesoporous SBA-15 solid acid provided by the present invention is used as a catalyst, the hydrophobic groups in its structure effectively inhibit the side reactions such as the rehydration of 5-hydroxymethylfurfural caused by the participation of water, and the sulfonate groups as catalytic sites significantly increase the yield of the target product.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a hydrophobic ordered mesoporous SBA-15 solid acid, comprising the following steps:

[0008] An organic template, an organic silicon source, an inorganic strong acid aqueous solution, phosphotungstic acid and a first organic silane are mixed and subjected to a hydrothermal reaction to obtain a hydrophobic ordered mesoporous SBA-15 precursor; the first organic silane has a methoxy group;

[0009] calcining the hydrophobic ordered mesoporous SBA-15 precursor to obtain a hydrophobic SBA-15 molecular sieve;

[0010] The hydrophobic SBA-15 molecular sieve, a second organic silane and an organic solvent are mixed and grafted to obtain a thiol-grafted hydrophobic SBA-15 molecular sieve; the second organic silane has a thiol group;

[0011] The hydrophobic SBA-15 molecular sieve modified by thiol grafting, an oxidant and a polar solvent are mixed to carry out thiol oxidation reaction to obtain the hydrophobic ordered mesoporous SBA-15 solid acid.

[0012] Preferably, the organic template is a triblock copolymer of polyethylene oxide-polypropylene oxide-polyethylene oxide;

[0013] The organic silicon source is methyl orthosilicate and / or ethyl orthosilicate;

[0014] The inorganic strong acid aqueous solution is a hydrochloric acid solution, and the molar concentration of the hydrochloric acid solution is 1 to 4 mol / L;

[0015] The first organic silane is methyltrimethoxysilane.

[0016] Preferably, the mass ratio of the organic template to the organosilicon source is (2-5):(8-10);

[0017] The ratio of the mass of the organic silicon source to the volume of the inorganic strong acid aqueous solution is (8-10) g: (90-120) mL;

[0018] The mass ratio of the organic template and phosphotungstic acid is (2-5):(0.8-0.9);

[0019] The ratio of the mass of the organic silicon source to the volume of the first organic silane is (8-10) g: (0.1-10) mL.

[0020] Preferably, the temperature of the hydrothermal reaction is 80-110° C., and the insulation time of the hydrothermal reaction is 24-40 hours.

[0021] Preferably, the calcination temperature is 350-550° C., the calcination holding time is 4-8 hours, and the calcination is carried out in an air atmosphere.

[0022] Preferably, the second organosilane is (3-mercaptopropyl)trimethoxysilane;

[0023] The ratio of the mass of the hydrophobic SBA-15 molecular sieve to the volume of the second organic silane is 1 g: (0.1-5) mL.

[0024] The present invention provides a hydrophobic ordered mesoporous SBA-15 solid acid prepared by the preparation method described in the above technical scheme, wherein the hydrophobic ordered mesoporous SBA-15 solid acid has a hydrophobic group and a sulfonate group; the hydrophobic group is a methoxy group.

[0025] Preferably, the hydrophobic ordered mesoporous SBA-15 solid acid The molar content of acid sites is 200-500 μmol·g -1 ; The molar content of total acid is 3 to 8 mmol·g -1 .

[0026] The present invention provides the use of the hydrophobic ordered mesoporous SBA-15 solid acid described in the above technical solution in catalyzing the production of 5-hydroxymethylfurfural from biomass raw materials.

[0027] Preferably, the biomass raw material comprises one or more of cellulose, cellulose hydrolysate, starch, fructose and inulin;

[0028] The mass ratio of the biomass raw material to the hydrophobic ordered mesoporous SBA-15 solid acid is 1:1.

[0029] The invention provides a preparation method of a hydrophobic ordered mesoporous SBA-15 solid acid, comprising the following steps: mixing an organic template, an organosilicon source, an inorganic strong acid aqueous solution, phosphotungstic acid and a first organosilane, performing a hydrothermal reaction, and obtaining a hydrophobic ordered mesoporous SBA-15 precursor; the first organosilane has a methoxy group; calcining the hydrophobic ordered mesoporous SBA-15 precursor to obtain a hydrophobic SBA-15 molecular sieve; mixing the hydrophobic SBA-15 molecular sieve, a second organosilane and an organic solvent, performing grafting modification, and obtaining a hydrophobic SBA-15 molecular sieve modified by thiol grafting; the second organosilane has a thiol group; mixing the hydrophobic SBA-15 molecular sieve modified by thiol grafting, an oxidant and a polar solvent, performing a thiol oxidation reaction, and obtaining the hydrophobic ordered mesoporous SBA-15 solid acid. The present invention first coats the organosilicon source with an organic template, and obtains an ordered mesoporous structure of silica supported by the organic template through hydrothermal treatment, wherein the addition of phosphotungstic acid effectively increases the stability of the ordered mesoporous pore wall of silica; at the same time, the present invention adds a first organosilane during the hydrothermal reaction, and in situ grafts the methoxy group of the first organosilane into the mesoporous channel to increase its hydrophobic ability. After calcination to remove the organic template, the present invention grafts the thiol group of the second organosilane onto the hydrophobic ordered mesoporous SBA-15 through an impregnation method, and uses an oxidant to oxidize the thiol group to a sulfonate group as an acidic catalytic site of the hydrophobic ordered mesoporous SBA-15, and finally obtains a hydrophobic ordered mesoporous SBA-15 solid acid catalyst. The present invention is based on functional modification of the inner structure of the SBA-15 zeolite molecular sieve pore channel, increasing the content of hydrophobic groups inside the ordered mesoporous pore channel by a first organic silane, and enhancing the acid strength of the ordered mesoporous SBA-15 solid acid by a second organic silane; the prepared hydrophobic ordered mesoporous SBA-15 solid acid not only shows excellent catalytic performance in catalytic biomass raw material conversion preparation, but also can effectively prevent water molecules from participating in the reaction process and thus causing side reactions by inhibiting the diffusion of water molecules in the reaction solvent and water molecules generated during the reaction process into the molecular sieve pore channel, thereby significantly reducing the concentration of by-products such as formic acid (FA) and levulinic acid (LA).

[0030] The preparation method of the hydrophobic ordered mesoporous SBA-15 solid acid provided by the present invention is simple and easy to implement, has high reproducibility and is green and environmentally friendly.

[0031] The present invention provides a hydrophobic ordered mesoporous SBA-15 solid acid prepared by the preparation method described in the above technical solution, wherein the hydrophobic ordered mesoporous SBA-15 solid acid has a hydrophobic group and a sulfonate group; the hydrophobic group is a methoxy group. It has been determined that the specific surface area of ​​the hydrophobic ordered mesoporous SBA-15 solid acid provided by the present invention is 300 to 550 m 2 ·g -1, the pore size is 5.0-10.0 nm, the hydrophobic ordered mesoporous SBA-15 solid acid prepared by the present invention is used as a catalyst, the hydrophobic groups in the hydrophobic ordered mesoporous SBA-15 solid acid effectively inhibit the side reactions such as the rehydration of 5-hydroxymethylfurfural caused by the participation of water, and the sulfonate group as a catalytic site significantly increases the yield of the target product. Therefore, the hydrophobic ordered mesoporous SBA-15 solid acid provided by the present invention shows extremely high catalytic activity, stability and renewable and reusable performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the adsorption-desorption curve and pore size distribution diagram of the ordered mesoporous SBA-15 solid acid prepared in Example 1;

[0033] Figure 2 is the X-ray diffraction pattern of the ordered mesoporous SBA-15 solid acid prepared in Example 1;

[0034] Figure 3 is a scanning electron microscope image of the ordered mesoporous SBA-15 solid acid prepared in Example 1;

[0035] Figure 4 is a transmission electron microscopy image of the ordered mesoporous SBA-15 solid acid prepared in Example 1;

[0036] Figure 5 is the pyridine infrared spectrum of the ordered mesoporous SBA-15 solid acid prepared in Example 1;

[0037] Figure 6 This is a diagram of the NH3 temperature-programmed desorption of the ordered mesoporous SBA-15 solid acid prepared in Example 1;

[0038] Figure 7 is a bar graph showing the yield of 5-hydroxymethylfurfural prepared by the ordered mesoporous SBA-15 solid acid prepared in Example 1 by catalyzing the conversion of microcrystalline cellulose at different temperatures;

[0039] Figure 8 This is a schematic diagram of the reaction principle of ordered mesoporous SBA-15 solid acid catalysis prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0040] The present invention provides a method for preparing a hydrophobic ordered mesoporous SBA-15 solid acid, comprising the following steps:

[0041] An organic template, an organic silicon source, an inorganic strong acid aqueous solution, phosphotungstic acid and a first organic silane are mixed and subjected to a hydrothermal reaction to obtain a hydrophobic ordered mesoporous SBA-15 precursor; the first organic silane has a methoxy group;

[0042] calcining the hydrophobic ordered mesoporous SBA-15 precursor to obtain a hydrophobic SBA-15 molecular sieve;

[0043] The hydrophobic SBA-15 molecular sieve, a second organic silane and an organic solvent are mixed and grafted to obtain a thiol-grafted hydrophobic SBA-15 molecular sieve; the second organic silane has a thiol group;

[0044] The hydrophobic SBA-15 molecular sieve modified by thiol grafting, an oxidant and a polar solvent are mixed to carry out thiol oxidation reaction to obtain the hydrophobic ordered mesoporous SBA-15 solid acid.

[0045] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0046] The present invention mixes an organic template, an organosilicon source, an inorganic strong acid aqueous solution, phosphotungstic acid and a first organosilane (hereinafter referred to as the first mixture) and performs a hydrothermal reaction to obtain a hydrophobic ordered mesoporous SBA-15 precursor; the first organosilane has a methoxy group.

[0047] In the present invention, the organic template is preferably a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123 copolymer).

[0048] In the present invention, the organic silicon source is preferably methyl orthosilicate and / or ethyl orthosilicate, more preferably methyl orthosilicate or ethyl orthosilicate, and further preferably ethyl orthosilicate.

[0049] In the present invention, the inorganic strong acid aqueous solution is preferably a hydrochloric acid solution, and the molar concentration of the hydrochloric acid solution is preferably 1 to 4 mol / L, more preferably 2 to 3 mol / L.

[0050] In the present invention, the first organic silane is preferably methyltrimethoxysilane.

[0051] In the present invention, the mass ratio of the organic template to the organosilicon source is preferably (2-5):(8-10), and more preferably (4-5):(8.4-8.5).

[0052] In the present invention, the ratio of the mass of the organosilicon source to the volume of the inorganic strong acid aqueous solution is (8-10) g:(90-120) mL, and more preferably (8.4-8.5) g:(110-120) mL.

[0053] In the present invention, the mass ratio of the organic template to phosphotungstic acid is preferably (2-5):(0.8-0.9), and more preferably (4-5):(0.84-0.86).

[0054] In the present invention, the ratio of the mass of the organosilicon source to the volume of the first organosilane is preferably (8-10) g:(0.1-10) mL, and more preferably (8.4-8.5) g:(6-8) mL.

[0055] In the present invention, the temperature of the first mixing is preferably 30-60°C, more preferably 40-60°C; the first mixing is preferably carried out under stirring, and the stirring speed is preferably 400-600r / min, more preferably 400-500r / min; the stirring time is preferably 24-40h, more preferably 24-36h.

[0056] In the present invention, the first mixing order is preferably: dissolving the organic template in the inorganic strong acid aqueous solution to obtain a first mixed solution; mixing the first mixed solution, an organic silicon source and a first organic silane to obtain a second mixed solution; and mixing the second mixed solution with the phosphotungstic acid.

[0057] In the present invention, the hydrothermal reaction is preferably carried out in a closed high-pressure reactor.

[0058] In the present invention, the hydrothermal reaction temperature is preferably 80 to 110° C., more preferably 100 to 105° C.; the hydrothermal reaction insulation time is preferably 24 to 40 h, more preferably 24 to 36 h.

[0059] In the present invention, a hydrothermal reaction liquid is obtained after the hydrothermal reaction. In the present invention, the hydrothermal reaction liquid is preferably post-treated to obtain the hydrophobic ordered mesoporous SBA-15 precursor. In the present invention, the post-treatment preferably includes: sequentially performing solid-liquid separation, washing with water to remove the solid product, and drying to obtain the hydrophobic ordered mesoporous SBA-15 precursor. In the present invention, the solid-liquid separation is specifically preferably suction filtration.

[0060] In the present invention, during the first mixing, the organic template can orderly coat the organosilicon source together, and then obtain the ordered mesoporous structure of silica supported by the organic template during the hydrothermal reaction. The present invention preferably uses phosphotungstic acid to effectively increase the stability of the ordered mesoporous pore walls of silica. At the same time, during the hydrothermal reaction, the first organosilane is in-situ grafted into the formed mesoporous channels to increase its hydrophobic ability. Since the medium reaction of the first organosilane and the hydrothermal generation of ordered mesoporous silica by the organosilicon source are carried out simultaneously, the hydrocarbon groups in the first organosilane can be in-situ grown on the pore walls of the ordered mesopores, thereby effectively increasing the content of hydrophobic groups in the hydrophobic ordered mesoporous SBA-15 precursor pores.

[0061] The present invention preferably adjusts: the mass ratio of the organic template and the organosilicon source is preferably (2-5): (8-10), more preferably (4-5): (8.4-8.5); the mass ratio of the organosilicon source to the volume of the inorganic strong acid aqueous solution is (8-10) g: (90-120) mL, more preferably (8.4-8.5) g: (110-120) mL; the mass ratio of the organic template and phosphotungstic acid is preferably (2-5): (0.8-0.9), more preferably (4-5): (0.84-0.86); the mass ratio of the organosilicon source to the volume of the first organosilane is preferably (8-10) g: (0.1-10) mL, more preferably (8.4-8.5) g: (6-8) mL, so as to obtain a hydrophobic ordered mesoporous SBA-15 solid acid catalyst with a large specific surface area and a suitable pore size.

[0062] After obtaining the hydrophobic ordered mesoporous SBA-15 precursor, the present invention calcines the hydrophobic ordered mesoporous SBA-15 precursor to obtain a hydrophobic SBA-15 molecular sieve.

[0063] In the present invention, the calcination temperature is preferably 350-550° C., more preferably 350-450° C.; the calcination holding time is preferably 4-8 hours, more preferably 4-5 hours; and the calcination is preferably carried out in an air atmosphere.

[0064] After obtaining the hydrophobic SBA-15 molecular sieve, the present invention mixes the hydrophobic SBA-15 molecular sieve, a second organic silane and an organic solvent for grafting modification to obtain a thiol-grafted hydrophobic SBA-15 molecular sieve; the second organic silane has a thiol group.

[0065] In the present invention, the second organic silane is preferably (3-mercaptopropyl)trimethoxysilane.

[0066] In the present invention, the organic solvent is preferably toluene.

[0067] In the present invention, the ratio of the mass of the hydrophobic SBA-15 molecular sieve to the volume of the second organic silane is preferably 1 g: (0.1-5) mL, more preferably 1 g: (1-2) mL.

[0068] The present invention has no special requirement on the amount of the organic solvent, as long as the grafting modification is carried out smoothly.

[0069] In the present invention, the graft modification is preferably carried out at room temperature, and the graft modification is carried out under stirring, and the stirring time is preferably 1 hour.

[0070] In the present invention, after the grafting modification, a grafting reaction liquid is obtained. In the present invention, the grafting reaction liquid is preferably post-treated to obtain the hydrophobic SBA-15 molecular sieve modified by the thiol grafting. In the present invention, the post-treatment preferably includes: sequentially subjecting the grafting reaction liquid to static precipitation, solid-liquid separation, and solid product drying. In the present invention, the solid-liquid separation is preferably filtration.

[0071] The hydrophobic SBA-15 molecular sieve modified by thiol grafting, an oxidant and a polar solvent are mixed to carry out thiol oxidation reaction to obtain the hydrophobic ordered mesoporous SBA-15 solid acid.

[0072] In the present invention, the oxidant is hydrogen peroxide, and in the present invention, the oxidant is preferably used in the form of an aqueous hydrogen peroxide solution. In the present invention, the mass percentage of the aqueous hydrogen peroxide solution is preferably 30%.

[0073] In the present invention, the polar solvent is preferably methanol and water. The water is preferably deionized water.

[0074] In the present invention, the volume ratio of the aqueous hydrogen peroxide solution, the methanol and water is preferably (5-20):(5-20):(10-30), and more preferably (5-10):(10-15):(20-30).

[0075] In the present invention, the thiol oxidation reaction is preferably carried out at room temperature, the thiol oxidation reaction is preferably carried out under stirring, and the stirring time is preferably 12 hours.

[0076] In the present invention, after the sulfhydryl oxidation reaction, an oxidation reaction liquid is obtained. In the present invention, the oxidation reaction liquid is preferably post-treated to obtain the hydrophobic ordered mesoporous SBA-15 solid acid. In the present invention, the post-treatment preferably includes: sequentially performing solid-liquid separation on the oxidation reaction liquid and drying the solid product. In the present invention, the solid-liquid separation is preferably filtration.

[0077] The present invention provides the above-mentioned preparation method, preferably adjusting the content of hydrophobic groups inside the ordered mesoporous channels by changing the amount of trimethoxysilane, preferably adjusting the amount of (3-mercaptopropyl)trimethoxysilane so that the ordered mesoporous SBA-15 solid acid catalyst has different acid strengths.

[0078] The present invention provides a hydrophobic ordered mesoporous SBA-15 solid acid prepared by the preparation method described in the above technical scheme, wherein the hydrophobic ordered mesoporous SBA-15 solid acid has a hydrophobic group and a sulfonate group; the hydrophobic group is a methoxy group.

[0079] In the present invention, the hydrophobic ordered mesoporous SBA-15 solid acid The molar content of acid sites is 200-500 μmol·g -1 ; The molar content of total acid is 3-8 mmol·g -1 .

[0080] The hydrophobic ordered mesoporous SBA-15 solid acid provided by the present invention has a highly regular and ordered two-dimensional hexagonal mesoporous channel structure and a uniform mesopore diameter.

[0081] In the present invention, the specific surface area of ​​the hydrophobic ordered mesoporous SBA-15 solid acid is preferably 300 to 550 m 2 ·g -1 The pore size is preferably 5.0 to 10.0 nm.

[0082] In the present invention, the hydrophobic group content of the hydrophobic ordered mesoporous SBA-15 solid acid significantly affects the morphology of the hydrophobic ordered mesoporous SBA-15 solid acid. As the hydrophobic group content increases, the hydrophobic ordered mesoporous SBA-15 solid acid changes from a short rod shape to a curved long rod shape.

[0083] The present invention provides the use of the hydrophobic ordered mesoporous SBA-15 solid acid described in the above technical solution in the catalytic reaction of generating 5-hydroxymethylfurfural from biomass raw materials.

[0084] The hydrophobic ordered mesoporous SBA-15 solid acid prepared by the present invention is used as a catalyst and shows extremely high catalytic activity, stability and reproducible and reusable performance.

[0085] In the present invention, the biomass raw material preferably includes one or more of cellulose, cellulose hydrolysate, starch, fructose and inulin. The cellulose hydrolysate preferably includes one or more of cellobiose, microcrystalline cellulose and glucose.

[0086] The hydrophobic groups in the hydrophobic ordered mesoporous SBA-15 solid acid provided by the present invention effectively inhibit side reactions such as 5-hydroxymethylfurfural rehydration caused by the participation of water, and the sulfonate groups as catalytic sites significantly increase the yield of the target product.

[0087] In the present invention, the application preferably comprises the following steps:

[0088] The biomass raw material, hydrophobic ordered mesoporous SBA-15 solid acid, 1-butyl-3-methylimidazole chloride, water and 2-sec-butylphenol are mixed and catalytically reacted to obtain the 5-hydroxymethylfurfural.

[0089] In the present invention, the water is preferably deionized water. The present invention has no special requirements on the amount of the water, as long as the catalytic reaction is ensured to proceed smoothly.

[0090] In the present invention, the mass ratio of the biomass raw material to the hydrophobic ordered mesoporous SBA-15 solid acid is 1:1.

[0091] In the present invention, the mass ratio of the biomass raw material to 1-butyl-3-methylimidazolium chloride is preferably 0.1:1.

[0092] In the present invention, the ratio of the mass of the biomass raw material to the volume of 2-sec-butylphenol is preferably 0.1 g:10 mL.

[0093] In the present invention, the catalytic reaction is preferably carried out in a stainless steel reactor with a polytetrafluoroethylene liner.

[0094] In the present invention, the temperature of the catalytic reaction is preferably 180° C., and the insulation time of the catalytic reaction is preferably 2 h.

[0095] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of the present invention so that those skilled in the art can well understand and utilize the present invention, rather than limiting the scope of protection of the present invention.

[0096] The names and abbreviations of the experimental methods, production processes, instruments and equipment involved in the embodiments and comparative examples of the present invention are conventional names in the field and are very clear and unambiguous in the relevant application fields. Those skilled in the art can understand the conventional process steps and apply the corresponding equipment based on the names and implement them according to conventional conditions or conditions recommended by the manufacturer.

[0097] The various raw materials or reagents used in the examples and comparative examples of the present invention are not particularly limited in terms of their sources, and are all conventional products that can be purchased commercially, or can be prepared according to conventional methods well known to those skilled in the art.

[0098] Example 1

[0099] 4.0 g of P123 copolymer was dissolved in 120 mL of 2M hydrochloric acid solution, stirred at 40°C for 8 h, 0.85 g of ethyl orthosilicate and 2 mL of trimethoxysilane were added to the mixed solution and the stirring was continued for 1 h, followed by the addition of 0.85 g of phosphotungstic acid and the stirring was continued for 24 h; the mixed solution was transferred to a sealed autoclave, heated to 100°C for hydrothermal reaction for 24 h, the reaction product was taken out, filtered, washed and dried to obtain an ordered mesoporous SBA-15 precursor; the ordered mesoporous SBA-15 precursor was heated to 450°C in air for calcination for 5 h to obtain a hydrophobic SBA-15 molecular sieve;

[0100] 1.0 g of the hydrophobic SBA-15 molecular sieve and 1.2 mL of (3-mercaptopropyl) trimethoxysilane were dispersed in 30 mL of toluene and stirred at room temperature for 1 h; the resulting white solid powder was collected by precipitation, filtration and drying; the white solid powder was dispersed in a mixed solvent consisting of 5 mL of hydrogen peroxide, 25 mL of deionized water and 10 mL of methanol, and stirred at room temperature for 12 hours to obtain a hydrophobic ordered mesoporous SBA-15 solid acid catalyst.

[0101] Test Example 1

[0102] Depend on Figure 1 The N2 adsorption-desorption curve and pore size distribution of the hydrophobic ordered mesoporous SBA-15 solid acid catalyst show that the hydrophobic ordered mesoporous SBA-15 solid acid catalyst shows a type IV adsorption isotherm accompanied by an H4 type hysteresis loop, indicating that the synthesized solid acid catalyst has a uniform ordered mesoporous distribution. The adsorption and desorption isotherms increase significantly in the range of P / P0 of 0.6-0.7, the average pore size is about 6.00nm, and the mesoporous specific surface area is 471.12m 2 g -1 .

[0103] Depend on Figure 2 The X-ray diffraction pattern of the hydrophobic ordered mesoporous SBA-15 solid acid catalyst shows that the peak at 2θ=23.3° comes from the amorphous carbon introduced by trimethoxysilane. A strong diffraction peak appears at 2θ=0.89° corresponding to the (100) crystal plane, which is a characteristic peak of the hexagonal p6mm mesoporous silica molecular sieve. At the same time, obvious diffraction peaks of the (110) and (200) crystal planes appear at 2θ=1.55° and 1.79°, indicating that the crystal structure of the SBA-15 silica carrier still exists.

[0104] Figure 3 The scanning electron microscopy image of the hydrophobic ordered mesoporous SBA-15 solid acid catalyst shows that the solid acid catalyst has a short rod-like morphology, and the introduction of hydrophobic groups and sulfonate groups does not destroy the morphological structure of the solid acid catalyst.

[0105] Figure 4 The transmission electron microscopy image of the hydrophobic ordered mesoporous SBA-15 solid acid catalyst shows that after grafting hydrophobic groups and sulfonate groups, the solid acid catalysis still maintains the typical p6mm structure with an ordered two-dimensional array.

[0106] Depend on Figure 5 The pyridine infrared spectrum of the hydrophobic ordered mesoporous SBA-15 solid acid catalyst shows that the introduced hydrophobic groups replace the hydrophilic hydroxyl groups on the original skeleton, and the introduction of sulfonate groups makes the solid acid catalyst have a hydrophobicity of 237.31 μmol g -1 of Acidic, and at 1638.61, 1546.56cm -1 Obvious observations Acidic site characteristic peak. At 1620.31cm -1 The characteristic peak of Lewis acidic site comes from the phosphotungstic acid heteroatom introduced into the SBA-15 molecular sieve framework.

[0107] Depend on Figure 6 The NH3 temperature-programmed desorption of hydrophobic ordered mesoporous SBA-15 solid acid catalyst is shown in the figure. The solid acid catalyst shows weak acidity at 102 °C desorption temperature, and shows two obvious medium-strong acid site peaks at 369 and 497 °C desorption temperatures. The contents of weak acid sites and medium-strong acid sites are 0.32 and 2.92 mmol g, respectively, calculated by peak area. -1 .

[0108] The solid acid catalyst prepared as above was used to catalyze the conversion of microcrystalline cellulose to prepare 5-hydroxymethylfurfural, so as to investigate the catalytic performance of the solid acid catalyst.

[0109] Application Example 1

[0110] 0.1g microcrystalline cellulose, 100mg hydrophobic ordered mesoporous SBA-15 solid acid catalyst, 1g 1-butyl-3-methylimidazolium chloride, 5mL deionized water and 10mL 2-sec-butylphenol were placed in a 100mL stainless steel reactor with a polytetrafluoroethylene liner and reacted for 2h at different reaction temperatures; after the reaction, the aqueous phase and the organic phase were separated by a 100mL separatory funnel and diluted with ethanol. The yield of 5-hydroxymethylfurfural was calculated by high performance liquid chromatography.

[0111] Catalytic evaluation results ( Figure 7 ) shows that with the increase of reaction temperature, the yield of 5-hydroxymethylfurfural shows a trend of first increasing and then decreasing. Too low or too high reaction temperature is not conducive to the formation of 5-hydroxymethylfurfural. When the reaction temperature is 160°C, the yield of 5-hydroxymethylfurfural is only 6.92%. At this time, the reaction degree of 5-hydroxymethylfurfural generation is low, and a long reaction time is required, and 5-hydroxymethylfurfural has poor stability, so it will be converted into other by-products. When the reaction temperature is 200°C, the yield of 5-hydroxymethylfurfural is 21.70%. This is because the excessively high reaction temperature promotes the formation of 5-hydroxymethylfurfural while also accelerating other side reactions. When the reaction temperature is 180°C, the yield of 5-hydroxymethylfurfural reaches a maximum of 61.24%.

[0112] It can be seen that the hydrophobic ordered mesoporous SBA-15 solid acid exhibits excellent catalytic activity in the process of catalyzing the conversion of microcrystalline cellulose to prepare 5-hydroxymethylfurfural.

[0113] Example 2

[0114] 4.0 g of P123 copolymer was dissolved in 120 mL of 2M hydrochloric acid solution, stirred at 40° C. for 8 h, 0.85 g of ethyl orthosilicate and 4 mL of trimethoxysilane were added to the mixed solution and the stirring was continued for 1 h, and then 0.85 g of phosphotungstic acid was added and the stirring was continued for 24 h; the mixed solution was transferred to a sealed high-pressure reactor, heated to 100° C. for hydrothermal reaction for 24 h, the reaction product was taken out, filtered, washed and dried to obtain an ordered mesoporous SBA-15 precursor; the ordered mesoporous SBA-15 precursor was heated to 450° C. in air and calcined for 5 h to obtain a hydrophobic SBA-15 molecular sieve;

[0115] 1.0 g of the above-mentioned hydrophobic SBA-15 molecular sieve and 1.2 mL of (3-mercaptopropyl)trimethoxysilane were dispersed in 30 mL of toluene and stirred at room temperature for 1 hour; the obtained white solid powder was collected by precipitation, filtration and drying; the white solid powder was dispersed in a mixed solvent consisting of 5 mL of hydrogen peroxide, 25 mL of deionized water and 10 mL of methanol, and stirred at room temperature for 12 hours to obtain a hydrophobic ordered mesoporous SBA-15 solid acid catalyst.

[0116] The characterization results of XRD and N2 adsorption-desorption confirmed that the hydrophobic ordered mesoporous SBA-15 solid acid catalyst prepared in Example 2 has a highly regular ordered two-dimensional hexagonal mesoporous channel structure and uniform mesopore diameter. By calculation, the specific surface area and average pore diameter of the solid acid catalyst are 514.48 m 2 g -1 and 5.66nm. Scanning electron microscope images show that the diameter of the hydrophobic ordered mesoporous SBA-15 solid acid catalyst becomes smaller, but the length increases. The acidic site content was 268.45 μmol g -1 .

[0117] Application Example 2

[0118] 0.1 g of microcrystalline cellulose, 100 mg of hydrophobic ordered mesoporous SBA-15 solid acid catalyst, 1 g of 1-butyl-3-methylimidazole chloride, 5 mL of deionized water and 10 mL of 2-sec-butylphenol were placed in a stainless steel reactor with a 100 mL polytetrafluoroethylene liner and reacted at 180° C. for 2 h. After the reaction, the aqueous phase and the organic phase were separated by a 100 mL separatory funnel and diluted with ethanol. The yield of 5-hydroxymethylfurfural was calculated to be 44.93% by high performance liquid chromatography.

[0119] Example 3

[0120] 4.0 g of P123 copolymer was dissolved in 120 mL of 2M hydrochloric acid solution, stirred at 40° C. for 8 h, 0.85 g of ethyl orthosilicate and 8 mL of trimethoxysilane were added to the mixed solution and the stirring was continued for 1 h, and then 0.85 g of phosphotungstic acid was added and the stirring was continued for 24 h; the mixed solution was transferred to a closed high-pressure reactor, heated to 100° C. for hydrothermal reaction for 24 h, the reaction product was taken out, filtered, washed and dried to obtain an ordered mesoporous SBA-15 precursor; the ordered mesoporous SBA-15 precursor was heated to 450° C. in air and calcined for 5 h to obtain a hydrophobic SBA-15 molecular sieve;

[0121] 1.0 g of the above-mentioned hydrophobic SBA-15 molecular sieve and 1.2 mL of (3-mercaptopropyl)trimethoxysilane were dispersed in 30 mL of toluene and stirred at room temperature for 1 hour; the obtained white solid powder was collected by precipitation, filtration and drying; the white solid powder was dispersed in a mixed solvent consisting of 5 mL of hydrogen peroxide, 25 mL of deionized water and 10 mL of methanol, and stirred at room temperature for 12 hours to obtain a hydrophobic ordered mesoporous SBA-15 solid acid catalyst.

[0122] The characterization results of XRD and N2 adsorption-desorption confirmed that the hydrophobic ordered mesoporous SBA-15 solid acid catalyst prepared in this example has a highly regular ordered two-dimensional hexagonal mesoporous channel structure and uniform mesopore diameter. By calculation, the specific surface area and average pore diameter of the solid acid catalyst are 530.73 m 2 g -1 and 5.62nm. Scanning electron microscope images show that the hydrophobic ordered mesoporous SBA-15 solid acid catalyst changes from short rods to curved long rods, and the diameter is significantly reduced. The acidic site content was 307.06 μmol g -1 .

[0123] Application Example 3

[0124] 0.1 g of microcrystalline cellulose, 100 mg of hydrophobic ordered mesoporous SBA-15 solid acid catalyst, 1 g of 1-butyl-3-methylimidazole chloride, 5 mL of deionized water and 10 mL of 2-sec-butylphenol were placed in a stainless steel reactor with a 100 mL polytetrafluoroethylene liner and reacted at 180°C for 2 h. After the reaction, the aqueous phase and the organic phase were separated by a 100 mL separatory funnel and diluted with ethanol. The yield of 5-hydroxymethylfurfural was calculated to be 3.94% by high performance liquid chromatography. This may be due to the excessive hydrophobic groups, which inhibit the transmission of substrates and intermediates inside the pores of the solid acid catalyst, reduce the contact area between the reaction substrate and the catalytic site, and thus are not conducive to the formation of 5-hydroxymethylfurfural.

[0125] Application Example 4

[0126] The hydrophobic ordered mesoporous SBA-15 solid acid catalyst prepared in Example 1 was used to catalyze starch conversion to prepare 5-hydroxymethylfurfural, and the catalytic performance of the solid acid catalyst was investigated.

[0127] 0.1g starch, 100mg hydrophobic ordered mesoporous SBA-15 solid acid catalyst, 1g 1-butyl-3-methylimidazolium chloride, 5mL deionized water and 10mL 2-sec-butylphenol were placed in a 100mL stainless steel reactor with a polytetrafluoroethylene liner and reacted at 180°C for 2h. After the reaction, the aqueous phase and the organic phase were separated by a 100mL separatory funnel and diluted with ethanol. The yield of 5-hydroxymethylfurfural was calculated to be 31.92% by high performance liquid chromatography.

[0128] Application Example 5

[0129] The hydrophobic ordered mesoporous SBA-15 solid acid catalyst prepared in Example 1 was used to catalyze the conversion of inulin to prepare 5-hydroxymethylfurfural, and the catalytic performance of the solid acid catalyst was investigated.

[0130] 0.1g inulin, 100mg hydrophobic ordered mesoporous SBA-15 solid acid catalyst, 1g 1-butyl-3-methylimidazolium chloride, 5mL deionized water and 10mL 2-sec-butylphenol were placed in a 100mL polytetrafluoroethylene liner stainless steel reactor and reacted at 180°C for 2h. After the reaction, the aqueous phase and the organic phase were separated by a 100mL separatory funnel and diluted with ethanol. The yield of 5-hydroxymethylfurfural was calculated by high performance liquid chromatography to be 49.51%.

[0131] Application Example 6

[0132] The hydrophobic ordered mesoporous SBA-15 solid acid catalysts prepared in Example 1 and Example 3 were used to catalyze the conversion of fructose to prepare 5-hydroxymethylfurfural, respectively, and the effects of the hydrophobicity and acidity of the solid acid catalyst on the preparation of 5-hydroxymethylfurfural were investigated.

[0133] 0.1g fructose, 100mg hydrophobic ordered mesoporous SBA-15 solid acid catalyst, 1g 1-butyl-3-methylimidazole chloride, 5mL deionized water and 10mL 2-sec-butylphenol were placed in a 100mL stainless steel reactor with a polytetrafluoroethylene liner and reacted at 140°C for 1-5h. After the reaction, the aqueous phase and the organic phase were separated by a 100mL separatory funnel and diluted with ethanol. The reaction rates of fructose conversion to prepare 5-hydroxymethylfurfural catalyzed by the hydrophobic ordered mesoporous SBA-15 solid acid catalyst prepared in Example 1 and Example 3 were 0.4853 and 0.3978s, respectively. -1 This proves that the hydrophobicity and acidity of the hydrophobic ordered mesoporous SBA-15 solid acid catalyst significantly affect the production rate of 5-hydroxymethylfurfural.

[0134] The above embodiments of the present invention do not describe all the details in detail, nor limit the present invention to the above embodiments. Various changes, modifications, substitutions and variations made by ordinary technicians in this field without departing from the principles and purpose of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a hydrophobic ordered mesoporous SBA-15 solid acid, characterized in that: The following steps are involved: An organic template, an organic silicon source, an inorganic strong acid aqueous solution, phosphotungstic acid and a first organic silane are mixed and subjected to a hydrothermal reaction to obtain a hydrophobic ordered mesoporous SBA-15 precursor; the first organic silane has a methoxy group; the mass ratio of the organic template and the phosphotungstic acid is (2-5):(0.8-0.9); calcining the hydrophobic ordered mesoporous SBA-15 precursor to obtain a hydrophobic SBA-15 molecular sieve; The hydrophobic SBA-15 molecular sieve, a second organic silane and an organic solvent are mixed and grafted to obtain a thiol-grafted hydrophobic SBA-15 molecular sieve; the second organic silane has a thiol group; The hydrophobic SBA-15 molecular sieve modified by thiol grafting, an oxidant and a polar solvent are mixed to carry out thiol oxidation reaction to obtain the hydrophobic ordered mesoporous SBA-15 solid acid.

2. The preparation method according to claim 1, characterized in that: The organic template is a triblock copolymer of polyethylene oxide-polypropylene oxide-polyethylene oxide; The organic silicon source is methyl orthosilicate and / or ethyl orthosilicate; The inorganic strong acid aqueous solution is a hydrochloric acid solution, and the molar concentration of the hydrochloric acid solution is 1 to 4 mol / L; The first organic silane is methyltrimethoxysilane.

3. The preparation method according to claim 2, characterized in that: The mass ratio of the organic template to the organosilicon source is (2-5):(8-10); The ratio of the mass of the organic silicon source to the volume of the inorganic strong acid aqueous solution is (8-10) g: (90-120) mL; The ratio of the mass of the organic silicon source to the volume of the first organic silane is (8-10) g: (0.1-10) mL.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The temperature of the hydrothermal reaction is 80-110° C., and the insulation time of the hydrothermal reaction is 24-40 hours.

5. The preparation method according to claim 1, characterized in that: The calcination temperature is 350-550° C., the calcination holding time is 4-8 hours, and the calcination is carried out in an air atmosphere.

6. The preparation method according to claim 1, characterized in that: The second organosilane is (3-mercaptopropyl)trimethoxysilane; The ratio of the mass of the hydrophobic SBA-15 molecular sieve to the volume of the second organic silane is 1 g: (0.1-5) mL.

7. The hydrophobic ordered mesoporous SBA-15 solid acid prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The hydrophobic ordered mesoporous SBA-15 solid acid has a hydrophobic group and a sulfonate group; the hydrophobic group is a methoxy group.

8. The hydrophobic ordered mesoporous SBA-15 solid acid according to claim 7, characterized in that: The hydrophobic ordered mesoporous SBA-15 solid acid The molar content of acid sites is 200-500 μmol·g -1 ; The molar content of total acid is 3 to 8 mmol·g -1 .

9. Use of the hydrophobic ordered mesoporous SBA-15 solid acid according to claim 7 or 8 in catalyzing the production of 5-hydroxymethylfurfural from biomass raw materials.

10. The use according to claim 9, characterized in that: The biomass raw material includes one or more of cellulose, cellulose hydrolysate, starch, fructose and inulin; The mass ratio of the biomass raw material to the hydrophobic ordered mesoporous SBA-15 solid acid is 1:1.

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