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CN-121974314-A - Method for preparing crystalline phase aluminum phosphate at low temperature through evaporation-induced self-assembly and catalytic application thereof

CN121974314ACN 121974314 ACN121974314 ACN 121974314ACN-121974314-A

Abstract

The invention discloses a method for preparing crystalline phase aluminum phosphate at low temperature through evaporation-induced self-assembly and catalytic application thereof, and relates to the technical field of catalyst preparation. The method comprises the steps of adding aqueous nitric acid solution and aluminum alkoxide into absolute ethyl alcohol, stirring and dissolving, adding aqueous phosphoric acid solution, then pre-reacting to obtain a mixture, heating the mixture to evaporate a solvent to obtain a solid product, calcining the solid product to obtain crystalline phase aluminum phosphate, wherein the molar ratio of phosphorus element contained in the aqueous phosphoric acid solution to aluminum element contained in the aluminum alkoxide is 1.5:1, and the calcining temperature is 550 ℃. The crystalline phase aluminum phosphate catalyst prepared by the method has higher reaction activity and product selectivity for catalyzing the reaction of formaldehyde and glycol acetal to synthesize 1, 3-dioxolane, and fewer byproducts.

Inventors

  • ZOU XIUJING
  • ZHANG YIXIAO
  • WEN YU
  • ZHAO JINGWEN
  • WANG XUEGUANG
  • SHANG XINGFU

Assignees

  • 上海大学

Dates

Publication Date
20260505
Application Date
20260320

Claims (10)

  1. 1. A method for preparing crystalline phase aluminum phosphate at low temperature by evaporation-induced self-assembly, comprising the steps of: Adding aqueous solution of nitric acid and aluminum alkoxide into absolute ethyl alcohol, stirring and dissolving, adding aqueous solution of phosphoric acid, and then carrying out pre-reaction to obtain a mixture; Heating the mixture to evaporate the solvent to obtain a solid product; Calcining the solid product to obtain the crystalline phase aluminum phosphate; the molar ratio of the phosphorus element contained in the phosphoric acid aqueous solution to the aluminum element contained in the aluminum alkoxide is 1.5:1; the calcination temperature was 550 ℃.
  2. 2. The method for preparing crystalline phase aluminum phosphate by evaporation-induced self-assembly at low temperature according to claim 1, wherein the aluminum alkoxide comprises aluminum isopropoxide, aluminum sec-butoxide or aluminum ethoxide.
  3. 3. The method for producing crystalline phase aluminum phosphate by evaporation-induced self-assembly at low temperature as claimed in claim 1, wherein the concentration of the aqueous nitric acid solution is 67wt%; and/or the concentration of the phosphoric acid aqueous solution is 85wt%.
  4. 4. The method for preparing crystalline phase aluminum phosphate by evaporation-induced self-assembly at low temperature according to claim 1, wherein the ratio of the amount of absolute ethanol, the aqueous nitric acid solution and the amount of aluminum alkoxide is 200ml:16ml:0.1mol.
  5. 5. The method for preparing crystalline aluminum phosphate by evaporation induced self-assembly at low temperature as claimed in claim 1, wherein the heating temperature is 40 to 80 ℃.
  6. 6. The method for preparing crystalline phase aluminum phosphate at low temperature by evaporation induced self-assembly according to claim 1, wherein the calcination time is 2 to 10 hours.
  7. 7. The method for preparing crystalline aluminum phosphate by evaporation-induced self-assembly at low temperature as claimed in claim 1, wherein the pre-reaction comprises stirring reaction at a temperature of 20 to 30 ℃ for 4 to 6 hours.
  8. 8. A crystalline phase aluminum phosphate prepared by the method of any one of claims 1-7 for low temperature preparation of crystalline phase aluminum phosphate by evaporation-induced self-assembly.
  9. 9. Use of crystalline phase aluminum phosphate according to claim 8 for catalyzing the reaction of formaldehyde and ethylene glycol acetals to synthesize 1, 3-dioxolane.
  10. 10. The method according to claim 9, wherein the acetalization reaction conditions comprise a molar ratio of formaldehyde to ethylene glycol of 1.1:1, a reaction temperature of 150℃and a reaction space velocity of 1 mL. G -1 ·h -1 .

Description

Method for preparing crystalline phase aluminum phosphate at low temperature through evaporation-induced self-assembly and catalytic application thereof Technical Field The invention relates to the technical field of catalyst preparation, in particular to a method for preparing crystalline phase aluminum phosphate at a low temperature by evaporation-induced self-assembly and catalytic application thereof. Background The mesoporous alumina material has excellent structural characteristics, and can be repeatedly prepared and conveniently utilized. The advantages can expand the synthesis method into the synthesized aluminum-based composite oxide, and the obtained oxide has the characteristics of regular mesoporous structure, uniform pore diameter structure and the like, thereby improving the stability of the catalyst for reaction. In recent years, phosphorus has been used as a modifier for modifying materials such as molecular sieves, carbon materials, and alumina. Currently, modification of catalyst support alumina by phosphorus is mainly reflected in two aspects, namely, improving the thermal stability of the alumina and changing the chemical properties of the alumina surface to adjust the acid-base performance of the alumina. Aluminum phosphate (AlPO 4) and its derivatives are an important class of materials whose crystalline phase forms (e.g., phosphoquartz type, cristobalite type) generally have excellent thermal stability and specific acidity. However, obtaining high crystallinity aluminum phosphate generally requires a relatively high temperature (generally above 700 ℃) to heat treat the amorphous precursor for a long period of time. Such high temperature processes inevitably lead to sinter densification of the material, a sharp drop in specific surface area and complete collapse of the pore structure, which is limiting in many applications requiring high specific surface areas and accessible active sites (e.g. heterogeneous catalysis). The phosphorus is introduced mainly by an impregnation method and a sol-gel method. The impregnation method is to load the active components on the existing carrier, the pore structure cannot be controlled, and the active components are easy to disperse unevenly. The product structure obtained by the traditional sol-gel method is mainly determined by chemical (pH, concentration) and thermodynamic factors, and precise mesostructure design is difficult to carry out. The evaporation-induced self-assembly is used as a higher-level sol-gel method, the product structure is dominated by the self-assembly behavior of the template agent, the predictability is strong, the pore canal arrangement is regular, the pore diameter distribution is very narrow, and the catalyst with high activity can be synthesized. The evaporation induced self-assembly (EISA) method is an effective means for preparing ordered mesoporous materials with high specific surface area, but the skeleton of traditional EISA products (such as mesoporous silica) is mostly amorphous. If the amorphous aluminum phosphate precursor obtained by EISA is crystallized at high temperature, the mesostructure of the amorphous aluminum phosphate precursor is destroyed, and the amorphous aluminum phosphate precursor falls into the two difficulties of 'having holes and no crystals and no holes'. Therefore, developing a method that can achieve the transition of the EISA-derived precursor to the crystalline phase at as low a heat treatment temperature as possible and minimize the collapse of the structure is a key to obtaining a high performance crystalline phase porous aluminum phosphate material, and also has significant technical challenges. 1,3-Dioxolane (1, 3-Dioxolane, DOL), an alias dioxolane or dioxolane, is a colorless clear liquid at normal temperature, has a chemical formula of C3H6O2, CAS:646-06-0, has a relative molecular weight of 74.08, a boiling point of 75.4 (760 mmHg), a density of 1.060g/cm3 (20 ℃) and is completely miscible with water and soluble in ethanol, diethyl ether and acetone. 1,3-dioxolane has a wide variety of uses. Including but not limited to solvents, extractants, crosslinking agents, plasticizers, electrolytes, comonomers, stabilizers for halogenated organic solvents, pharmaceutical intermediates. The 1,3-dioxolane is prepared by acid catalyzed condensation of formaldehyde and glycol. In the traditional synthesis process, the catalyst used in the 1,3-dioxolane synthesis reactor is sulfuric acid, and the sulfuric acid is selected as the catalyst because of the high acid value of the sulfuric acid, the good catalytic effect and the convenient operation of adding the sulfuric acid. However, sulfuric acid belongs to inorganic strong acid, has strong corrosiveness, causes harm to the service life of equipment, and has high requirements on the material of the equipment. Therefore, the equipment of the 1,3-dioxolane synthesis part must all use zirconium as a corrosion-resistant material, which results in