Glycerin modified mesoporous SBA-15 loaded phosphorus and aluminum AlPx / SBA-15-GL solid acid catalyst synthesized by impregnation method

Abstract

The invention belongs to the technical field of catalyst preparation, and particularly relates to a glycerol modified mesoporous SBA-15 loaded phosphorus and aluminum AlPx / SBA-15-GL solid acid catalyst synthesized by an impregnation method. The preparation method comprises the following steps: firstly, dissolving a template agent in hydrochloric acid to obtain a template agent-hydrochloric acid solution; uniformly mixing a silicon source and glycerol to obtain a precursor; the preparation method comprises the following steps: mixing a precursor with a template agent-hydrochloric acid solution, carrying out co-assembly treatment, aging treatment, drying and stepped roasting to obtain glycerol modified mesoporous SBA-15, taking the glycerol modified mesoporous SBA-15 as a carrier, preparing an AlPx / SBA-15-GL series catalyst through an impregnation method, synthesizing glycerol acetal in the reaction of formaldehyde and glycerol acetal by using the catalyst, and carrying out solid-liquid separation to obtain the AlPx / SBA-15-GL series catalyst. The catalyst has excellent conversion rate and excellent stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and more specifically relates to a glycerol-modified mesoporous SBA-15 loaded with phosphorus aluminum AlP synthesized by an impregnation method. x / SBA-15-GL solid acid catalyst. Background Art

[0002] Supported catalysts are a type of heterogeneous catalyst in which the active components are uniformly dispersed and fixed on a carrier. Their core advantage lies in optimizing the dispersion, stability, and mechanical strength of the active components through the carrier's support. They are widely used in industrial catalysis, energy, environmental protection, and other fields.

[0003] The aluminum phosphate catalyst used in the past is an inorganic functional material constructed based on aluminum and phosphorus. Due to its unique acidic characteristics, it exhibits high activity and high selectivity in chemical reactions. However, this catalyst has two significant shortcomings:

[0004] First, the microporous structure limits the diffusion efficiency of reactants;

[0005] Secondly, under high temperature environment, the active components will easily agglomerate, resulting in a decrease in specific surface area.

[0006] Therefore, in some studies, SBA-15 mesoporous molecular sieves have been further introduced as carriers. SBA-15 is a typical two-dimensional hexagonal mesoporous molecular sieve material. The formation of its unique structural characteristics is due to the hydrothermal crystallization synthesis process using the triblock copolymer P123 as a template. This material has a highly ordered hexagonal pore structure, and the pore size can be precisely controlled in the range of 5-30nm. This feature completely breaks through the diffusion limitations of traditional microporous materials and has been widely used in the field of catalysis. The large pore size of SBA-15 allows large molecular reactants to diffuse freely, and its high specific surface area provides dispersed anchoring points for active components, while the thick pore wall structure enhances the hydrothermal stability of the material, ensuring that the pore skeleton can still maintain its integrity under high temperature or high pressure reaction conditions, avoiding performance degradation due to structural collapse. However, using a single SBA-15 mesoporous molecular sieve as a carrier has problems such as strong hydrophilicity, a single active site, easy pore clogging, and insufficient stability.

[0007] Glycerol formal, a colorless, transparent, viscous liquid, is primarily composed of 5-hydroxy-1,3-dioxane and 4-methyl-1,3-dioxolane. Its CAS number is 4740-78-7, its molecular formula is C₄H₄O₃, its molecular weight is 104.1, its boiling point is 192-193°C (lit.), and its density is 1.203 g / mL at 25°C (lit.), miscible in water and ethanol (96%). Glycerol formal is used as a solvent for pesticide and pharmaceutical injections, a cosolvent for chemical and dye emulsifiers, and in the formulation of related liquids such as ivermectin / avermectin injections and long-acting oxytetracycline injections. It is also used in cosmetics, pesticides, coatings, high-grade inks, and foundry industries. Traditionally, glycerol formal is produced using an acid-catalyzed synthesis process. Specifically, formaldehyde and glycerol are synthesized through an acetalization reaction using strong acids such as sulfuric acid and hydrochloric acid as catalysts. In this reaction, the strong acid catalyst activates the carbonyl group of formaldehyde by providing a proton, lowering the activation energy of the reaction and promoting the condensation of the hydroxyl group on the glycerol molecule with the carbonyl group of formaldehyde, ultimately producing glycerol formal. This method is mature, but it is associated with a number of issues, including high catalyst corrosion, difficulty in product separation, numerous side reactions (such as dehydration and carbonization), and environmental pollution.

[0008] Although the traditional acid catalysis method is a classic preparation process for glycerol formal, which is mature, low-cost and simple to operate, it is limited by corrosion, side reactions and environmental issues. It is necessary to find a new catalytic method to solve the problems existing in the traditional acid catalysis method. In the preparation process of glycerol formal, catalysts with SBA-15, mesoporous alumina (Al2O3), pure silicon mesoporous materials (MCM-41, etc.), titanium oxide (TiO2), and activated carbon as carriers have many problems in structure, performance, application, etc. In terms of structure, mesoporous materials are easily affected by hydrothermal effects, causing pore collapse, and the micropores of activated carbon affect mass transfer; in terms of performance, the surface acidity and alkalinity are difficult to control, the active components are not firmly loaded, and are prone to agglomeration and loss, and the carrier has a poor hydrophilic-hydrophobic balance, which affects the adsorption of reactants and the reaction; in terms of application, catalyst regeneration is easy to destroy the structure, and the adaptability to complex environments is poor, making it difficult to meet the demand for industrial-grade raw materials. What is important is that due to problems such as changes in acid-base centers, loss of active components, and coking and deactivation, its stability is poor, which in turn leads to its poor catalytic performance. Therefore, how to provide a stable acid-aluminum catalyst with excellent catalytic performance has become a difficult problem that technicians in this field urgently need to overcome. Summary of the Invention

[0009] The purpose of the present invention is to provide a glycerol modified mesoporous SBA-15 loaded with phosphorus aluminum AlP synthesized by impregnation method x / SBA-15-GL solid acid catalyst to solve the problems existing in the above-mentioned prior art.

[0010] To achieve the above object, the present invention provides the following solutions:

[0011] One of the technical solutions of the present invention is to provide a method for preparing glycerol-modified mesoporous SBA-15, comprising the following steps:

[0012] dissolving the template in hydrochloric acid to obtain a template-hydrochloric acid solution;

[0013] Mixing the silicon source and glycerol uniformly to obtain a precursor;

[0014] The precursor is mixed with the template-hydrochloric acid solution, and subjected to co-assembly treatment, aging treatment, drying and step-baking to obtain the glycerol-modified mesoporous SBA-15 (SBA-15-GL).

[0015] Glycerol modification can improve the surface hydrophilic-hydrophobic balance. The multiple hydroxyl groups and short carbon chains of glycerol give the material amphiphilicity, enhancing its dispersibility in multiphase systems. It can increase multiple active sites, and its hydroxyl groups can directly participate in acid-base catalysis or be derived into more functional groups. It can also stably load metal particles. It can also optimize pore performance, regulate pore polarity, selectively adsorb target substrates and prevent clogging. It can also improve stability and biocompatibility, strengthen the skeleton through hydrogen bonds, and reduce nonspecific adsorption.

[0016] Furthermore, the template includes at least one of P123, F127 and Brij-58, preferably P123.

[0017] Furthermore, the concentration of the hydrochloric acid is 1.5-3.0 mol / L, preferably 2 mol / L.

[0018] Optionally, the usage ratio of the template agent and hydrochloric acid is 10-25 g:600-800 mL, preferably 20 g:600 mL.

[0019] Hydrochloric acid creates an acidic environment for the solution, which is beneficial for the self-assembly of P123 molecules. Under acidic conditions, the hydrophilic end of P123 is protonated, enhancing its interaction with the inorganic silicon source, prompting the silicon source to form a specific ordered structure around P123, ultimately forming the mesoporous structure of SBA-15. Furthermore, an appropriate amount of hydrochloric acid can bring the hydrolysis and polycondensation reaction rates of the silicon source (such as ethyl orthosilicate) into an appropriate range. If the acidity is too high or too low, it will affect the degree of hydrolysis and polycondensation of the silicon source, thereby affecting the structure and properties of the mesoporous material. For example, sulfuric acid, which is highly acidic, may cause the hydrolysis and polycondensation rate of the silicon source to be too rapid, resulting in a decrease in the order of the mesoporous structure. Nitric acid is oxidizing and may undergo redox reactions with certain substances in the system, thus affecting the synthesis process.

[0020] Furthermore, the silicon source includes at least one of ethyl orthosilicate, sodium silicate and methyl silicate, preferably ethyl orthosilicate.

[0021] Furthermore, the mass ratio of the template, silicon source and glycerol is 1:2-3:0.8-1, preferably 20:42.5:18.7.

[0022] Furthermore, the co-assembly process is carried out by stirring at 30-45° C. for 12-24 hours, preferably, at 40° C. for 24 hours.

[0023] Furthermore, the aging treatment is aging at 90-100°C for 12-24 hours, preferably, aging at 90°C for 24 hours.

[0024] Furthermore, the drying is carried out at 90-100° C. for 6-12 hours, preferably at 100° C. for 12 hours.

[0025] Furthermore, the step calcination is heating to 300°C at a heating rate of 1-2°C / min, calcining for 4-8h, and then heating to 600°C at a heating rate of 1-2°C / min, and calcining for 4-8h.

[0026] Optionally, the step calcination is heating to 300° C. at a heating rate of 1° C. / min, calcining for 8 hours, and then heating to 600° C. at a heating rate of 2° C. / min, and calcining for 8 hours.

[0027] The present invention adopts a step-by-step calcination method. In the synthesis of SBA-15-GL, firstly, the pore structure is protected to prevent the template from instantaneously decomposing at high temperature to generate a large amount of gas that would collapse the mesoporous skeleton; secondly, the mesoporous properties are optimized, the primary silicon skeleton is stabilized at low temperature, and the pore wall strength is enhanced at high temperature, so that the pore diameter is uniform and the specific surface area is increased; thirdly, structural defects are eliminated, thermal stress is uniformly released by gradually increasing the temperature, and microcracks and pore distortion are reduced.

[0028] Organic (glycerol) modified SBA-15-GL can increase surface lipophilicity, change the physical and chemical properties of the material surface, and improve the catalytic performance of the material. Specifically:

[0029] (1) Enhanced lipophilicity:

[0030] The carbon chain structure of glycerol reduces surface polarity, increases contact angle, enhances adsorption capacity and dispersibility of oil-phase substrates, and significantly improves its compatibility and contact efficiency in organic catalytic reactions.

[0031] (2) Modification of physical and chemical properties:

[0032] Acidity and alkalinity regulation, electronic structure optimization: Glycerol hydroxyl groups make it easier for silicon hydroxyl groups to release protons (H+ ), improving the Brønsted acidity; at the same time, enhancing the electron deficiency of adjacent silicon atoms and strengthening the Lewis acidity.

[0033] (3) Synergistic improvement of catalytic performance:

[0034] The amphiphilic interface promotes efficient contact between oil and water substrates to optimize mass transfer through the lipophilic properties of the carbon chain and the hydrophilic properties of the hydroxyl group; in the synergistic effect of acid-base sites, the hydroxyl group enhances the acidic activation of the substrate, and the oxygen atoms act as base sites to promote the reaction process; the metal-carrier effect prevents agglomeration by anchoring metal particles and regulates the electronic state to enhance the adsorption and activation of the substrate; the covalent anchoring structure fixes the glycerol layer through covalent bonds, thereby improving the thermal stability and cycle life of the material and reducing the loss of active sites.

[0035] The second technical solution of the present invention is to provide a glycerol-modified mesoporous SBA-15, which is prepared by the above-mentioned preparation method.

[0036] The third technical solution of the present invention is to provide an application of the above-mentioned glycerol-modified mesoporous SBA-15 as a carrier in the field of catalyst preparation.

[0037] The fourth technical solution of the present invention is to provide a method for preparing a glycerol-modified mesoporous SBA-15-loaded phosphate-aluminum solid acid catalyst, comprising the following steps:

[0038] Dissolving an aluminum source, potassium sodium tartrate, and a phosphorus source in water to prepare an aluminum source solution, potassium sodium tartrate solution, and a phosphorus source solution, respectively;

[0039] The potassium sodium tartrate solution and the aluminum source solution are uniformly mixed, and the pH is adjusted to 2.5-3 to obtain an aluminum-tartaric acid complex solution;

[0040] After preparing ethylenediaminetetraacetic acid into an ethylenediaminetetraacetic acid solution with a pH of 8 to 9, adding the solution to the phosphorus source solution, mixing evenly, and adjusting the pH to 6 to obtain a phosphorus source chelate solution;

[0041] The glycerol-modified mesoporous SBA-15 is added to the aluminum-tartaric acid complex solution, and the phosphorus source chelating solution is added stepwise after impregnation. After uniform mixing, the pH value is adjusted to 6.5-7, the solvent is evaporated and stirred to dryness, and then dried and calcined to obtain a glycerol-modified mesoporous SBA-15-loaded phosphorus aluminum solid acid catalyst.

[0042] Furthermore, the aluminum source includes at least one of aluminum nitrate, aluminum sulfate and aluminum chloride hexahydrate.

[0043] Furthermore, the phosphorus source includes at least one of phosphoric acid, ammonium phosphate and ammonium dihydrogen phosphate.

[0044] Furthermore, the molar ratio of P in the phosphorus source to Al in the aluminum salt is 0-1.0, and is not 0.

[0045] Furthermore, the molar ratio of the aluminum source to sodium potassium tartrate is 1-1.2, preferably, an equimolar ratio.

[0046] Furthermore, the molar ratio of the ethylenediaminetetraacetic acid to the phosphorus in the phosphorus source is 0.1-0.15, preferably 0.1.

[0047] Optionally, the concentration of the EDTA solution is 0.007-0.1 mol / L.

[0048] Furthermore, the stepwise addition of the phosphorus source chelating solution is adding the phosphorus source chelating solution in at least two steps.

[0049] Furthermore, the temperature for evaporating the solvent and stirring it to dryness is 50-65°C, preferably 65°C.

[0050] Furthermore, the drying temperature is 90-100°C, preferably 100°C.

[0051] Furthermore, the calcination is performed by heating the temperature to 400-550° C. at a heating rate of 1-2° C. / min and calcining for 4-6 hours. Preferably, the calcination is performed by heating the temperature to 450° C. at a heating rate of 2° C. / min and calcining for 6 hours.

[0052] Furthermore, the total loading amount of phosphorus and aluminum in the glycerol-modified mesoporous SBA-15 loaded phosphorus and aluminum solid acid catalyst is 5-25 wt%.

[0053] The fifth technical solution of the present invention: provides a glycerol-modified mesoporous SBA-15-loaded phosphate-aluminum solid acid catalyst, and the glycerol-modified mesoporous SBA-15-loaded phosphate-aluminum solid acid catalyst is prepared by the above-mentioned preparation method.

[0054] Technical solution six of the present invention: provides an application of the above-mentioned glycerol-modified mesoporous SBA-15 loaded phosphate aluminum solid acid catalyst in catalyzing the reaction of formaldehyde and glycerol acetal.

[0055] The present invention discloses the following technical effects:

[0056] The invention uses glycerol-modified mesoporous SBA-15 as a carrier and synthesizes a phosphorus-aluminum-loaded solid acid catalyst by an impregnation method. The catalyst synthesizes glycerol formal in the reaction of formaldehyde and glycerol acetal with excellent conversion rate and good stability.

[0057] The glycerol-modified mesoporous SBA-15 loaded with phosphorus aluminum solid acid catalyst prepared by the present invention has high reaction activity and product selectivity in the reaction of catalyzing formaldehyde and glycerol acetal to synthesize glycerol formal, and has fewer by-products. Among them, the glycerol conversion rate can reach 76.7%, and the glycerol formal selectivity can reach 96.4%. After 120 hours of continuous reaction, the catalyst has a glycerol conversion rate of 52.3% and a glycerol formal selectivity of 95.3%, and its catalytic effect is still maintained at a relatively good level. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0059] Figure 1 The small-angle XRD spectra of the catalysts obtained in Examples 1-6 and Comparative Example 2 are shown.

[0060] Figure 2 The wide-angle XRD spectra of the catalysts obtained in Examples 1-6 and Comparative Example 2 are shown.

[0061] Figure 3 NH3-TPD spectra of the catalysts obtained in Examples 1-6 and Comparative Example 2.

[0062] Figure 4 The normalized specific surface area of ​​NH3 desorption at temperatures below 320°C for the catalysts obtained in Examples 1-6 and Comparative Example 2.

[0063] Figure 5 This is the SEM image of SBA-15-GL.

[0064] Figure 6 This is the SEM image of AlP0 / SBA-15-GL.

[0065] Figure 7 AlP 0.1 SEM image of / SBA-15-GL.

[0066] Figure 8 AlP 0.3 SEM image of / SBA-15-GL.

[0067] Figure 9 AlP 0.5 SEM image of / SBA-15-GL.

[0068] Figure 10 AlP 0.7 SEM image of / SBA-15-GL.

[0069] Figure 11 AlP1.0 SEM image of / SBA-15-GL.

[0070] Figure 12 AlP 0.7 / SBA-15-GL stability results chart. DETAILED DESCRIPTION

[0071] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0072] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0073] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0074] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0075] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0076] In some specific embodiments, the present invention provides a method for preparing glycerol-modified mesoporous SBA-15, comprising the steps of:

[0077] The template is dissolved in hydrochloric acid to obtain a template-hydrochloric acid solution; a silicon source and glycerol are mixed uniformly to obtain a precursor; the precursor is mixed with the template-hydrochloric acid solution, and the mixture is subjected to co-assembly treatment, aging treatment, drying and step calcination to obtain the glycerol-modified mesoporous SBA-15 (SBA-15-GL).

[0078] Glycerol modification can significantly improve hydrophobicity and optimize product selectivity. Specifically:

[0079] Glycerol formal (acetal) is hydrophobic, while the surface of unmodified SBA-15 is rich in hydrophilic silanol (Si-OH) groups, which strongly adsorb hydrophilic glycerol reactants and intermediates. This results in: Difficulty in product desorption: Hydrophobic products have difficulty desorbing from the hydrophilic surface, and retention leads to excessive condensation (such as the formation of polyglycerol or higher molecular weight byproducts). Pore blockage: Product accumulation blocks the pores, reducing mass transfer efficiency and accelerating catalyst deactivation.

[0080] Effects of glycerol modification: Surface hydrophobization: reduces the adsorption energy barrier of the carrier for glycerol formal. Selective desorption: promotes the rapid separation of hydrophobic products from active sites, significantly reduces deep side reactions, and improves the selectivity of glycerol formal.

[0081] Glycerol modification can significantly enhance the dispersion and anchoring stability of active ingredients. Specifically:

[0082] Aluminum source (strong Lewis acid) and phosphorus source (generated Acid sites) are easily aggregated on the hydrophilic SBA-15 due to high surface energy, resulting in uneven distribution of active sites, thereby reducing the number of effective active sites, leaching of active components, and Al 3+ It is easy to hydrolyze and lose in the reaction liquid, and the catalyst is quickly deactivated.

[0083] The hydrophobic layer after glycerol modification acts as a dispersion medium, reducing the surface energy of the carrier and inhibiting the migration and aggregation of active components; the hydroxyl anchoring effect, the residual hydroxyl group (-OH) of glycerol and Al 3+ PO4 3- Form coordination bonds or hydrogen bonds to enhance binding force.

[0084] Glycerol modification can precisely control surface acidity and inhibit side reactions. Specifically:

[0085] The weak acid Si-OH of unmodified SBA-15 will interfere with the reaction and interact with the strong Lewis acid sites (Al 3+ ) form competition, reduce the effective acid strength, and trigger side reactions such as glycerol dehydration (generating acrolein) or polymerization.

[0086] Glycerol modification can shield weak acid sites, cover most of the Si-OH, eliminate their negative effects, optimize the acid site microenvironment, wrap the active sites with a hydrophobic layer, limit the excessive adsorption of glycerol at strong acid sites, and inhibit side reaction pathways.

[0087] Glycerol modification can improve the pore mass transfer efficiency, specifically:

[0088] The hydrophilic pores of unmodified SBA-15 are easily occupied by glycerol / water molecules, hindering the diffusion of formaldehyde (gas phase) to the active sites; after glycerol modification, the hydrophobic pores preferentially adsorb formaldehyde (relatively hydrophobic) while repelling excess glycerol / water, optimizing the local concentration ratio of reactants at the active sites.

[0089] It can be seen that in the reaction of formaldehyde-glycerol condensation to produce glycerol formal, glycerol-modified SBA-15 promotes product desorption / inhibits side reactions through surface hydrophobicization, enhances active site anchoring, improves stability, and precisely adjusts the acidity to optimize the reaction path.

[0090] The achievement of a performance breakthrough in the trinity of high activity, high selectivity and long life is a key strategy to solve the mass transfer limitations and side reaction bottlenecks in this reaction.

[0091] In some specific embodiments, the present invention provides a method for preparing a glycerol-modified mesoporous SBA-15-loaded phosphate-aluminum solid acid catalyst, comprising the following steps:

[0092] Dissolving an aluminum source, potassium sodium tartrate, and a phosphorus source in water to prepare an aluminum source solution, potassium sodium tartrate solution, and a phosphorus source solution, respectively;

[0093] The potassium sodium tartrate solution and the aluminum source solution are uniformly mixed, subjected to aging treatment, and the pH is adjusted to 2.5-3 to obtain an aluminum-tartaric acid complex solution;

[0094] After preparing ethylenediaminetetraacetic acid (EDTA) into an EDTA solution with a pH of 8 to 9, add the solution to the phosphorus source solution, mix well, and adjust the pH to 6 to obtain a phosphorus source chelate solution;

[0095] The glycerol-modified mesoporous SBA-15 was added to the aluminum-tartaric acid complex solution, and after impregnation, the phosphorus source chelating solution was added stepwise. After mixing evenly, the pH value was adjusted to 6.5-7, the solvent was evaporated and stirred to dryness, and after drying and calcination, a glycerol-modified mesoporous SBA-15-loaded aluminum phosphorus solid acid catalyst was obtained. The catalyst was recorded as AlP x / SBA-15-GL, where x is the molar ratio of phosphorus to aluminum.

[0096] Potassium sodium tartrate forms a stable [Al(C4H4O6)2] -The complex inhibits the hydrolysis of aluminum ions to form aluminum hydroxide precipitates, ensuring a clear solution and uniform dispersion of the aluminum source. After complexation, adjusting the pH to a weakly acidic state further stabilizes the aluminum complex, preventing loss of catalyst active sites due to hydrolysis. This complexation allows the aluminum source to be uniformly adsorbed at the molecular level within the mesoporous channels of SBA-15-GL, preventing agglomeration and improving the uniformity of active site distribution. It also prevents the hydrolysis of aluminum salts from forming amorphous precipitates that clog the channels, ensuring the integrity of the carrier's mesoporous structure and facilitating subsequent phosphorus source loading and reactant diffusion.

[0097] The following uses ammonium dihydrogen phosphate as a phosphorus source to explain the role of EDTA:

[0098] Ethylenediaminetetraacetic acid (EDTA) forms an EDTA-phosphate chelate with the phosphate in ammonium dihydrogen phosphate. By adjusting the pH, the release rate of the phosphate is controlled to achieve a "gradient loading" of the phosphorus source.

[0099] H2Y 2- The EDTA in the form of phosphate combines with phosphate through hydrogen bonds or electrostatic interactions, delaying the deposition of the phosphorus source and promoting its layer-by-layer diffusion on the surface and in the pores of the aluminum-modified SBA-15-GL (SBA-15-GL immersed in an aluminum-tartaric acid complex solution), thereby achieving the effect of enhancing the interfacial interaction.

[0100] The phosphorus source chelating solution is added in a stepwise manner to load the phosphorus source in stages, thereby avoiding pore blockage or active site aggregation caused by a one-time high concentration of phosphorus salt, and forming an orderly distribution of "aluminum-phosphorus" active centers.

[0101] The sustained-release effect is used to reduce the damage to the mesoporous structure caused by the rapid deposition of phosphate salts, and an amorphous aluminum phosphate active phase is formed after calcination. At the same time, the high specific surface area and pore connectivity of SBA-15-GL are retained, thereby improving the efficiency of the catalytic reaction.

[0102] Potassium sodium tartrate solves the hydrolysis problem by complexing aluminum ions, ensuring uniform loading of the aluminum source and a stable mesoporous structure; EDTA achieves a gradient distribution of active components by slowly releasing the phosphorus source, avoiding pore blockage and optimizing the structure of the active center. The two work together to improve the activity, selectivity and stability of the catalyst.

[0103] The AlP synthesized by the impregnation method of the present invention x / SBA-15-GL series catalysts achieve adjustable acidity of the catalyst by changing the phosphorus-aluminum molar ratio, improving the surface acidity of the catalyst without destroying the mesoporous structure of SBA-15-GL. The inherent characteristics of SBA-15-GL slow down the carbon deposition rate of the catalyst, further improving the stability of the catalyst. x / SBA-15-GL catalyst is suitable for the acetalization reaction of formaldehyde and glycerol to prepare glycerol formal. It can promote the industrial production of glycerol formal and comply with the principles of green chemistry.

[0104] The raw materials and reagents used in the specific embodiments of the present invention are all commercially available products, and the purchase channels do not affect the realization of the technical effects.

[0105] Unless otherwise specified, the normal temperature and room temperature involved in the specific embodiments of the present invention refer to 20-30°C.

[0106] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0107] Example 1

[0108] Preparation of glycerol-modified SBA-15:

[0109] S1. Dissolve 20 g of P123 in 600 mL of 2 mol / L hydrochloric acid solution and stir continuously at 40° C. for 3 to 4 hours until the solution becomes clear and transparent to obtain a template-hydrochloric acid solution;

[0110] S2, 42.5 g of ethyl orthosilicate and 18.7 g of glycerol were mixed to obtain a precursor;

[0111] S3. Slowly add the precursor in step S2 dropwise to the template-hydrochloric acid solution in step S1, maintain the temperature at 40°C and continue stirring for 24 hours. After the stirring is completed, transfer the mixed solution into a PP bottle and bake it in a 90°C oven for 24 hours. After the baking is completed, take it out and cool it to room temperature, then filter it, dry the filter cake at 100°C for 12 hours, then heat it to 300°C at a heating rate of 1°C per minute and maintain it for 8 hours, finally heat it to 600°C at a heating rate of 2°C per minute and calcine it at this temperature for 8 hours to prepare glycerol-modified SBA-15, which is recorded as SBA-15-GL.

[0112] Example 2

[0113] The preparation steps of the glycerol-modified mesoporous SBA-15-loaded aluminum phosphate solid acid catalyst include:

[0114] S1. Dissolve 4.41 g of aluminum source (aluminum chloride hexahydrate) in 25 mL of deionized water in an ice-water bath to prepare an aluminum source solution;

[0115] Sodium potassium tartrate solution was prepared by dissolving 5.15 g of sodium potassium tartrate in 25 mL of deionized water;

[0116] Dissolve 0.21 g of phosphorus source (ammonium dihydrogen phosphate) in 25 mL of 65°C deionized water and cool to room temperature to prepare a phosphorus source solution;

[0117] S2. Under stirring, slowly add the potassium sodium tartrate solution in step S1 to the aluminum source solution in step S1, mix evenly for 1 hour, and then adjust the pH to between 2.5 and 3 to obtain an aluminum-tartaric acid complex solution;

[0118] S3, 10% phosphorus (phosphorus in ammonium dihydrogen phosphate) molar amount of ethylenediaminetetraacetic acid is configured into an ethylenediaminetetraacetic acid solution with a pH between 8 and 9 (concentration is 0.007 mol / L), then the above ethylenediaminetetraacetic acid solution is slowly added to the phosphorus source solution, after mixing, the pH value is adjusted to 6 with ammonia water to obtain a phosphorus source chelate solution;

[0119] S4, the aluminum-tartaric acid complex solution in step S2 is added with 6g of SBA-15-GL in Example 1, ultrasonically dispersed evenly, fully impregnated, and evenly mixed with the phosphorus source chelate solution in step S3, and the phosphorus source chelate solution is added twice, 1 / 3 volume of solution is added for the first time, and the remaining solution is added for the second time, and the pH of the solution is adjusted to about 6.5-7, and then placed in a 65°C water bath and stirred to dry. The dried solid is dried in an oven at 100°C and then heated to 450°C at a heating rate of 2°C / min, and calcined at this temperature for 6 hours to obtain a glycerol-modified mesoporous SBA-15-loaded aluminum phosphorus solid acid catalyst, recorded as AlP 0.1 / SBA-15-GL, wherein the loading amount of phosphorus aluminum is 15 wt%.

[0120] Example 3

[0121] The preparation steps of the glycerol-modified mesoporous SBA-15-loaded aluminum phosphate solid acid catalyst include:

[0122] S1. Dissolve 3.54 g of aluminum source (aluminum chloride hexahydrate) in 25 mL of deionized water in an ice-water bath to prepare an aluminum source solution;

[0123] Sodium potassium tartrate solution was prepared by dissolving 4.14 g of sodium potassium tartrate in 25 mL of deionized water;

[0124] Dissolve 0.51 g of phosphorus source (ammonium dihydrogen phosphate) in 25 mL of 65°C deionized water and cool to room temperature to prepare a phosphorus source solution;

[0125] S2. Under stirring, slowly add the potassium sodium tartrate solution in step S1 to the aluminum source solution in step S1, mix evenly for 1 hour, and then adjust the pH to between 2.5 and 3 to obtain an aluminum-tartaric acid complex solution;

[0126] S3, preparing an ethylenediaminetetraacetic acid solution (concentration of 0.018 mol / L) with a pH between 8 and 9 by a molar amount of 10% phosphorus (phosphorus in ammonium dihydrogen phosphate), then slowly adding the ethylenediaminetetraacetic acid solution to the phosphorus source solution, mixing well, and adjusting the pH to 6 with aqueous ammonia to obtain a phosphorus source chelate solution;

[0127] S4, the aluminum-tartaric acid complex solution in step S2 is added with 6g of SBA-15-GL in Example 1, ultrasonically dispersed evenly, fully impregnated, and evenly mixed with the phosphorus source chelate solution in step S3, and the phosphorus source chelate solution is added twice, 1 / 3 volume of solution is added for the first time, and the remaining solution is added for the second time, and the pH of the solution is adjusted to about 6.5-7, and then placed in a 65°C water bath and stirred to dry. The dried solid is dried in an oven at 100°C and then heated to 450°C at a heating rate of 2°C / min, and calcined at this temperature for 6 hours to obtain a glycerol-modified mesoporous SBA-15-loaded aluminum phosphorus solid acid catalyst, recorded as AlP 0.3 / SBA-15-GL, wherein the loading amount of phosphorus aluminum is 15 wt%.

[0128] Example 4

[0129] The preparation steps of the glycerol-modified mesoporous SBA-15-loaded aluminum phosphate solid acid catalyst include:

[0130] S1. Dissolve 2.96 g of aluminum source (aluminum chloride hexahydrate) in 25 mL of deionized water in an ice-water bath to prepare an aluminum source solution;

[0131] Sodium potassium tartrate solution was prepared by dissolving 3.46 g of sodium potassium tartrate in 25 mL of deionized water;

[0132] Dissolve 0.71 g of phosphorus source (ammonium dihydrogen phosphate) in 25 mL of 65°C deionized water and cool to room temperature to prepare a phosphorus source solution;

[0133] S2. Under stirring, slowly add the potassium sodium tartrate solution in step S1 to the aluminum source solution in step S1, mix evenly for 1 hour, and then adjust the pH to between 2.5 and 3 to obtain an aluminum-tartaric acid complex solution;

[0134] S3, 10% phosphorus (phosphorus in ammonium dihydrogen phosphate) molar amount of ethylenediaminetetraacetic acid is configured into an ethylenediaminetetraacetic acid solution (concentration is 0.025 mol / L) with a pH between 8 and 9, and then the above ethylenediaminetetraacetic acid solution is slowly added to the phosphorus source solution, after mixing, the pH value is adjusted to 6 with ammonia water to obtain a phosphorus source chelate solution;

[0135] S4, the aluminum-tartaric acid complex solution in step S2 is added with 6g of SBA-15-GL in Example 1, ultrasonically dispersed evenly, fully impregnated, and evenly mixed with the phosphorus source chelate solution in step S3, and the phosphorus source chelate solution is added twice, 1 / 3 volume of solution is added for the first time, and the remaining solution is added for the second time, and the pH of the solution is adjusted to about 6.5-7, and then placed in a 65°C water bath and stirred to dry. The dried solid is dried in an oven at 100°C and then heated to 450°C at a heating rate of 2°C / min, and calcined at this temperature for 6 hours to obtain a glycerol-modified mesoporous SBA-15-loaded aluminum phosphorus solid acid catalyst, recorded as AlP 0.5 / SBA-15-GL, wherein the loading amount of phosphorus aluminum is 15 wt%.

[0136] Example 5

[0137] The preparation steps of the glycerol-modified mesoporous SBA-15-loaded aluminum phosphate solid acid catalyst include:

[0138] S1. Dissolve 2.54 g of aluminum source (aluminum chloride hexahydrate) in 25 mL of deionized water in an ice-water bath to prepare an aluminum source solution;

[0139] Sodium potassium tartrate solution was prepared by dissolving 2.97 g of sodium potassium tartrate in 25 mL of deionized water;

[0140] Dissolve 0.85 g of phosphorus source (ammonium dihydrogen phosphate) in 25 mL of 65°C deionized water and cool to room temperature to prepare a phosphorus source solution;

[0141] S2. Under stirring, slowly add the potassium sodium tartrate solution in step S1 to the aluminum source solution in step S1, mix evenly for 1 hour, and then adjust the pH to between 2.5 and 3 to obtain an aluminum-tartaric acid complex solution;

[0142] S3, 10% phosphorus (phosphorus in ammonium dihydrogen phosphate) molar amount of ethylenediaminetetraacetic acid is configured into an ethylenediaminetetraacetic acid solution with a pH between 8 and 9 (concentration is 0.030 mol / L), then the above ethylenediaminetetraacetic acid solution is slowly added to the phosphorus source solution, after mixing, the pH value is adjusted to 6 with ammonia water to obtain a phosphorus source chelate solution;

[0143] S4, the aluminum-tartaric acid complex solution in step S2 is added with 6g of SBA-15-GL in Example 1, ultrasonically dispersed evenly, fully impregnated, and evenly mixed with the phosphorus source chelate solution in step S3, and the phosphorus source chelate solution is added twice, 1 / 3 volume of solution is added for the first time, and the remaining solution is added for the second time, and the pH of the solution is adjusted to about 6.5-7, and then placed in a 65°C water bath and stirred to dry. The dried solid is dried in an oven at 100°C and then heated to 450°C at a heating rate of 2°C / min, and calcined at this temperature for 6 hours to obtain a glycerol-modified mesoporous SBA-15-loaded aluminum phosphorus solid acid catalyst, recorded as AlP 0.7 / SBA-15-GL, wherein the loading amount of phosphorus aluminum is 15 wt%.

[0144] Example 6

[0145] The preparation steps of the glycerol-modified mesoporous SBA-15-loaded aluminum phosphate solid acid catalyst include:

[0146] S1. Dissolve 2.10 g of aluminum source (aluminum chloride hexahydrate) in 25 mL of deionized water in an ice-water bath to prepare an aluminum source solution;

[0147] Sodium potassium tartrate solution was prepared by dissolving 2.45 g of sodium potassium tartrate in 25 mL of deionized water;

[0148] Dissolve 1.00 g of a phosphorus source (ammonium dihydrogen phosphate) in 25 mL of 65°C deionized water and cool to room temperature to prepare a phosphorus source solution;

[0149] S2. Under stirring, slowly add the potassium sodium tartrate solution in step S1 to the aluminum source solution in step S1, mix evenly for 1 hour, and then adjust the pH to between 2.5 and 3 to obtain an aluminum-tartaric acid complex solution;

[0150] S3, 10% phosphorus (phosphorus in ammonium dihydrogen phosphate) molar amount of ethylenediaminetetraacetic acid is configured into an ethylenediaminetetraacetic acid solution with a pH between 8 and 9 (concentration is 0.035 mol / L), then the above ethylenediaminetetraacetic acid solution is slowly added to the phosphorus source solution, after mixing, the pH value is adjusted to 6 with ammonia water to obtain a phosphorus source chelate solution;

[0151] S4, the aluminum-tartaric acid complex solution in step S2 is added with 6g of SBA-15-GL in Example 1, ultrasonically dispersed evenly, fully impregnated, and evenly mixed with the phosphorus source chelate solution in step S3, and the phosphorus source chelate solution is added twice, 1 / 3 volume of solution is added for the first time, and the remaining solution is added for the second time, and the pH of the solution is adjusted to about 6.5-7, and then placed in a 65°C water bath and stirred to dry. The dried solid is dried in an oven at 100°C and then heated to 450°C at a heating rate of 2°C / min, and calcined at this temperature for 6 hours to obtain a glycerol-modified mesoporous SBA-15-loaded aluminum phosphorus solid acid catalyst, recorded as AlP 1.0 / SBA-15-GL, wherein the loading amount of phosphorus aluminum is 15 wt%.

[0152] Comparative Example 1

[0153] The preparation steps of the solid acid catalyst include:

[0154] S1. Dissolve 4.41 g of aluminum source (aluminum chloride hexahydrate) in 25 mL of deionized water in an ice-water bath to prepare an aluminum source solution;

[0155] Sodium potassium tartrate solution was prepared by dissolving 5.15 g of sodium potassium tartrate in 25 mL of deionized water;

[0156] Dissolve 0.21 g of phosphorus source (ammonium dihydrogen phosphate) in 25 mL of 65°C deionized water and cool to room temperature to prepare a phosphorus source solution;

[0157] S2. Under stirring, slowly add the potassium sodium tartrate solution in step S1 to the aluminum source solution in step S1, mix evenly for 1 hour, and then adjust the pH to between 2.5 and 3 to obtain an aluminum-tartaric acid complex solution;

[0158] S3, 10% phosphorus (phosphorus in ammonium dihydrogen phosphate) molar amount of ethylenediaminetetraacetic acid is configured into an ethylenediaminetetraacetic acid solution with a pH between 8 and 9 (concentration is 0.007 mol / L), then the above ethylenediaminetetraacetic acid solution is slowly added to the phosphorus source solution, after mixing, the pH value is adjusted to 6 with ammonia water to obtain a phosphorus source chelate solution;

[0159] S4, the aluminum-tartaric acid complex solution in step S2 and the phosphorus source chelate solution in step S3 are mixed evenly, then placed in a 65°C water bath and stirred to dry, the dried solid is dried in an oven at 100°C and then heated to 450°C at a heating rate of 2°C / min, and calcined at this temperature for 6 hours to obtain a solid acid catalyst, which is recorded as AlP 0.1 .

[0160] Comparative Example 2

[0161] The preparation steps of the glycerol-modified mesoporous SBA-15 aluminum-loaded solid acid catalyst include:

[0162] S1. Dissolve 5.02 g of aluminum source (aluminum chloride hexahydrate) in 25 mL of deionized water in an ice-water bath to prepare an aluminum source solution;

[0163] Sodium potassium tartrate solution was prepared by dissolving 5.86 g of sodium potassium tartrate in 25 mL of deionized water;

[0164] S2. Under stirring, slowly add the potassium sodium tartrate solution in step S1 to the aluminum source solution in step S1, mix evenly for 1 hour, and then adjust the pH to between 2.5 and 3 to obtain an aluminum-tartaric acid complex solution;

[0165] S3. Add 6 g of SBA-15-GL in Example 1 to the aluminum-tartaric acid complex solution in step S2, disperse it evenly by ultrasonication, adjust the pH of the solution to about 6.5-7, and then place it in a water bath at 65° C. and stir to dry. The dried solid is dried in an oven at 100° C. and then heated to 450° C. at a heating rate of 2° C. / min, and calcined at this temperature for 6 hours to obtain a glycerol-modified mesoporous SBA-15-loaded aluminum solid acid catalyst, recorded as AlP0 / SBA-15-GL, wherein the aluminum loading is 15 wt%.

[0166] Comparative Example 3

[0167] Compared with Example 2, the only difference is that the ordinary unmodified SBA-15 used in step S4 is denoted as AlP 0.1 / SBA-15.

[0168] Test example

[0169] The products prepared in Examples 1-6 and Comparative Examples 1-3 were used as catalysts in the acetalization reaction of formaldehyde and glycerol to prepare glycerol formal. The reaction was carried out in a fixed bed reactor under normal pressure. The reaction conditions were:

[0170] The catalyst was 0.5 g, the molar ratio of formaldehyde to glycerol was 1, the reaction temperature was 150 °C, and the reaction space velocity was 6 mL g -1 h -1 .

[0171] The glycerol conversion rate, glycerol formal selectivity and yield are shown in Table 1.

[0172] Table 1

[0173]

[0174] From the data in Table 1, it can be seen that SBA-15-GL with lower acid sites showed a glycerol conversion rate of 20.2%. This is because SBA-15-GL itself has a high specific surface area and large pore size, which is conducive to the adsorption and activation of reactants on its surface, and acetalization reaction occurs at a certain temperature, showing a certain catalytic effect. 0.1 Comparing the catalysts, the conversion rate of the catalyst prepared after SBA-15-GL loading was relatively high. This is because the large pore size of SBA-15-GL allows for free diffusion of reactants, and the high specific surface area provides dispersed anchoring sites for the active components, thus more conducive to the reaction. With increasing phosphorus-to-aluminum molar ratio, the glycerol conversion rate initially increases and then decreases. When the P / Al molar ratio increases from 0 to 0.7, the glycerol conversion rate rises from 47.6% to 76.7%, and the glycerol formal selectivity rises from 95.0% to 96.4%. When the P / Al molar ratio is further increased from 0.7 to 1.0, the glycerol conversion rate decreases from 76.7% to 60.3%, and the glycerol formal selectivity changes from 96.4% to 95.2%. This indicates that the phosphorus-to-aluminum ratio (P / Al molar ratio) is a key parameter for regulating catalyst performance, significantly affecting the catalyst's acidity and alkalinity, thermal stability, and the activity and selectivity of the target reaction. An appropriate P / Al ratio results in excellent catalytic performance.

[0175] Figures 1-4 In the example 2, x=0 is AlP0 / SBA-15-GL, and x=0.1 is AlP0 / SBA-15-GL. 0.1 / SBA-15-GL, x=0.3 is AlP in Example 3 0.3 / SBA-15-GL, x=0.5 is AlP in Example 4 0.5 / SBA-15-GL, x=0.7 is AlP in Example 5 0.7 / SBA-15-GL, x=1.0 is AlP in Example 6 1.0 / SBA-15-GL.

[0176] Figure 1 The low-angle XRD spectra of the catalysts obtained in Examples 1-6 and Comparative Example 2 are shown in the figure. As can be seen from the figure, the three diffraction peaks appearing in the low-angle XRD spectra correspond to the (100), (110), and (200) crystal planes of SBA-15-GL, respectively. As the phosphorus-to-aluminum ratio increases, the first main peak decreases and shifts to lower angles. When the phosphorus-to-aluminum ratio is 1.0, the second and third peaks disappear, indicating that when the phosphorus-to-aluminum ratio is large, blockage will occur, interfering with the orderly arrangement of the catalyst and affecting its long-range order.

[0177] Figure 2The wide-angle XRD spectra of the catalysts obtained in Examples 1-6 and Comparative Example 2 are shown. As can be seen from the figure, all samples exhibit a broad diffraction peak corresponding to amorphous silica near 2θ = 22.5°, with no other sharp characteristic peaks. This indicates that the phosphorus and aluminum species are uniformly dispersed in a highly amorphous state after loading. As the phosphorus-aluminum ratio increases, the peak shape changes from essentially unchanged to gradually broadening, indicating that excessive phosphorus-aluminum ratios gradually dilute the silica diffraction peaks.

[0178] Figure 3 NH3-TPD spectra of the catalysts obtained in Examples 1-6 and Comparative Example 2. As can be seen from the figure, SBA-15-GL has very few acidic sites. x A broad desorption peak of amorphous material appears in the / SBA-15-GL catalyst between 50 and 320 °C, which is divided into two peaks, located at weak acid and medium-strong acid sites respectively. Among them, AlP0 / SBA-15-GL mainly shows the presence of weak acid sites. When a certain phosphorus content is introduced, the number of medium-strong acid sites increases slightly.

[0179] Figure 4 The normalized specific surface area represents the NH3 desorption capacity at temperatures below 320°C for the catalysts obtained in Examples 1-6 and Comparative Example 2. As can be seen from the figure, as the phosphorus-to-aluminum ratio increases, the catalyst acidity increases first and then decreases. The catalyst acidity reaches its maximum when the P / Al molar ratio is 0.7, indicating that the phosphorus-to-aluminum ratio has a certain impact on the number and strength of acidic sites.

[0180] Figure 5 This is the SEM image of SBA-15-GL.

[0181] Figure 6 This is the SEM image of AlP0 / SBA-15-GL.

[0182] Figure 7 AlP 0.1 SEM image of / SBA-15-GL.

[0183] Figure 8 AlP 0.3 SEM image of / SBA-15-GL.

[0184] Figure 9 AlP 0.5 SEM image of / SBA-15-GL.

[0185] Figure 10 AlP 0.7 SEM image of / SBA-15-GL.

[0186] Figure 11 AlP 1.0SEM image of / SBA-15-GL.

[0187] Depend on Figure 5-Figure 11 As can be seen, SBA-15-GL exhibits the typical stripe-like morphology characteristic of SBA-15. After loading, phosphorus-like substances appear on the surface, indicating that the phosphorus and aluminum components exist on the catalyst surface as amorphous aluminum phosphate. Agglomeration becomes more pronounced as the phosphorus content increases. The formation of phosphorus-like substances is due to the interaction between phosphorus and aluminum on the SBA-15-GL matrix, which causes surface morphological changes. This change further disrupts the uniform distribution of active sites on the catalyst, affecting the overall catalytic performance. This is consistent with the aforementioned decrease in conversion and shift in XRD diffraction peaks with increasing phosphorus-aluminum ratio.

[0188] AlP 0.7 / SBA-15-GL was used as a catalyst in the acetalization reaction of formaldehyde and glycerol to prepare glycerol formal. The catalyst stability test was carried out. The results are as follows: Figure 12 As shown, the reaction is carried out in a fixed bed reactor under normal pressure, and the reaction conditions are:

[0189] The catalyst was 0.5 g, the molar ratio of formaldehyde to glycerol was 1, the reaction temperature was 150 °C, and the reaction space velocity was 6 mL g -1 h -1 , the reaction time is 120h.

[0190] Figure 12 AlP 0.7 / SBA-15-GL stability results. As shown in the figure, during the 120h test, the selectivity of glycerol formal did not change much, basically maintaining at around 95%, and the glycerol conversion rate remained at more than half of the activity. At 120h, the glycerol conversion rate was still 52.3%. This is because the high specific surface area and large pore size of SBA-15-GL itself can make the formed active sites evenly dispersed on the surface of SBA-15-GL, thereby reducing the probability of carbon deposition. This result also further shows that AlP 0.7 / The reasonable stability of SBA-15-GL catalyst meets the conditions for use in flow systems.

[0191] In summary, the AlP prepared by the impregnation method of the present invention xThe SBA-15-GL catalyst exhibited high conversion, selectivity, and excellent stability in the acetalization reaction of formaldehyde and glycerol to glycerol formal. The experiments demonstrated that the phosphorus-aluminum molar ratio can modulate the catalyst's acidity. The number of acidic sites on the catalyst first increased and then decreased with increasing phosphorus content, with weak acids predominating among weak and medium-strong acids. The bonding between the SBA-15-GL support and amorphous aluminum phosphate significantly enhanced interfacial stability, enabling the catalyst to maintain its pore structure even under high-temperature and hydrothermal conditions. Therefore, the catalyst has broad application prospects in the acetalization reaction of formaldehyde and glycerol to produce glycerol formal.

[0192] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0193] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing glycerol-modified mesoporous SBA-15, characterized in that the steps include: dissolving the template in hydrochloric acid to obtain a template-hydrochloric acid solution; Mixing the silicon source and glycerol uniformly to obtain a precursor; The precursor is mixed with the template-hydrochloric acid solution, and subjected to co-assembly treatment, aging treatment, drying and step calcination to obtain the glycerol-modified mesoporous SBA-15.

2. The preparation method according to claim 1, wherein The template includes at least one of P123, F127 and Brij-58; and / or the concentration of the hydrochloric acid is 1.5-3.0 mol / L; and / or the silicon source includes at least one of tetraethyl orthosilicate, sodium silicate and methyl silicate; and / or the mass ratio of the template, silicon source and glycerol is 1:2-3:0.8-1; and / or the co-assembly treatment is stirring at 30-45°C for 12-24h; and / or the aging treatment is aging at 90-100°C for 12-24h; and / or the drying is drying at 90-100°C for 6-12h; and / or the step calcination is heating to 300°C at a heating rate of 1-2°C / min, calcining for 4-8h, and then heating to 600°C at a heating rate of 1-2°C / min, and calcining for 4-8h.

3. The preparation method according to claim 2, wherein The usage ratio of the template agent and hydrochloric acid is 10-25 g:600-800 mL.

4. A glycerol-modified mesoporous SBA-15, characterized in that: The glycerol-modified mesoporous SBA-15 is prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the glycerol-modified mesoporous SBA-15 according to claim 4 as a carrier in the field of catalyst preparation.

6. A method for preparing a glycerol-modified mesoporous SBA-15-loaded aluminum-phosphorus solid acid catalyst, characterized in that the steps include: Dissolving an aluminum source, potassium sodium tartrate, and a phosphorus source in water to prepare an aluminum source solution, potassium sodium tartrate solution, and a phosphorus source solution, respectively; The potassium sodium tartrate solution and the aluminum source solution are uniformly mixed, and the pH is adjusted to 2.5-3 to obtain an aluminum-tartaric acid complex solution; After preparing ethylenediaminetetraacetic acid into an ethylenediaminetetraacetic acid solution with a pH of 8 to 9, the solution is added to the phosphorus source solution, mixed evenly, and the pH is adjusted to 6 to obtain a phosphorus source chelate solution; The glycerol-modified mesoporous SBA-15 according to claim 4 is added to the aluminum-tartaric acid complex solution, and the phosphorus source chelating solution is added stepwise after impregnation. After uniform mixing, the pH value is adjusted to 6.5-7, the solvent is evaporated and stirred to dryness, and then dried and calcined to obtain a glycerol-modified mesoporous SBA-15-loaded phosphorus aluminum solid acid catalyst.

7. The preparation method according to claim 6, wherein The aluminum source includes at least one of aluminum nitrate, aluminum sulfate and aluminum chloride hexahydrate; and / or the phosphorus source includes at least one of phosphoric acid, ammonium phosphate and ammonium dihydrogen phosphate; and / or the molar ratio of P in the phosphorus source to Al in the aluminum salt is 0-1.0 and not 0; and / or the molar ratio of the aluminum source to sodium potassium tartrate is 1-1.2; and / or the molar ratio of ethylenediaminetetraacetic acid to phosphorus in the phosphorus source is 0.1-0.

15.

8. The preparation method according to claim 6, wherein The stepwise addition of the phosphorus source chelating solution is to add the phosphorus source chelating solution in at least two steps; and / or, the temperature for evaporating the solvent and stirring it to dryness is 50-65° C.; and / or, the drying temperature is 90-100° C.; and / or, the calcination is to increase the temperature to 400-550° C. at a heating rate of 1-2° C. / min and calcinate for 4-6 hours; and / or, the total loading amount of phosphorus and aluminum in the glycerol-modified mesoporous SBA-15 loaded phosphorus and aluminum solid acid catalyst is 5-25wt%.

9. A glycerol-modified mesoporous SBA-15-loaded aluminum-phosphorus solid acid catalyst, characterized in that: The glycerol-modified mesoporous SBA-15-loaded aluminum-phosphorus solid acid catalyst is prepared by the preparation method according to any one of claims 6 to 8.

10. Use of the glycerol-modified mesoporous SBA-15 loaded with phosphorus aluminum solid acid catalyst according to claim 9 in catalyzing the reaction of formaldehyde and glycerol acetal.

Images