Search

CN-118403664-B - Polyacid zeolite imidazole ester skeleton loaded single-atom catalyst and preparation method and application thereof

CN118403664BCN 118403664 BCN118403664 BCN 118403664BCN-118403664-B

Abstract

The invention discloses a polyacid zeolite imidazole ester skeleton-supported single-atom catalyst, a preparation method and application thereof, belonging to the technical field of catalysts, wherein the preparation method of the catalyst comprises (1) preparing zeolite imidazole ester skeleton material; (2) mixing the dried zeolite imidazole ester framework material with metal salt in a solvent, stirring, adding heteropolyacid, controlling the pH value in the system to be 5-7, carrying out solvothermal reaction at 80-120 ℃, cooling and centrifugally separating after the reaction is finished to obtain a precipitate, and (3) calcining the precipitate to obtain the monoatomic catalyst loaded by the zeolite imidazole ester framework of the polyacid. The single-atom catalyst loaded on the polyacid zeolite imidazole ester skeleton prepared by the method has high catalytic activity, high selectivity and good cycling stability, and has good application prospect in levulinic acid esterification reaction.

Inventors

  • ZHANG HAICHUAN
  • HUANG BAOCHENG
  • Fan Niansi
  • JIN RENCUN

Assignees

  • 杭州师范大学

Dates

Publication Date
20260508
Application Date
20240320

Claims (7)

  1. 1. The application of the polyacid zeolite imidazole ester skeleton-loaded single-atom catalyst in catalyzing levulinic acid esterification reaction is characterized in that the preparation method of the polyacid zeolite imidazole ester skeleton-loaded single-atom catalyst comprises the following steps: (1) Preparing a zeolite imidazole ester framework material, wherein the zeolite imidazole ester framework material comprises ZIF-8 or ZIF-67; (2) Mixing the dried zeolite imidazole ester skeleton material with metal salt in a solvent, stirring, adding heteropolyacid, controlling the pH value in the system to be 5-7, carrying out solvothermal reaction at 80-120 ℃, cooling after the reaction is finished, and centrifugally separating to obtain a precipitate; (3) Calcining the precipitate to obtain the single-atom catalyst loaded by the polyacid zeolite imidazole ester skeleton; the metal salt is at least one of platinum salt, palladium salt, gold salt or silver salt; The heteropoly acid is Keggin type polyacid and contains [ XM 12 O 40 ] n- ions, wherein X is selected from P, si or Ge, M is selected from Mo, W, V or Nb, and n is an integer of 1-5; In the step (3), the calcination treatment is carried out under the atmosphere of hydrogen at the temperature of 200-600 ℃ for 2-4h.
  2. 2. The use according to claim 1, wherein the metal salt is selected from chloroplatinic acid hexahydrate, palladium chloride, or palladium acetate.
  3. 3. The use according to claim 1, wherein in step (2), the mass ratio of the zeolitic imidazolate framework material, the metal salt and the heteropolyacid is from 1:0.001 to 0.05:0.1 to 0.5, and the mass/volume ratio of the zeolitic imidazolate framework material to the solvent is from 1g:10 to 100 mL.
  4. 4. The use according to claim 1, wherein in step (2) the solvothermal reaction time is 2-6 h.
  5. 5. A method for preparing levulinate is characterized by taking levulinic acid and low-carbon alcohol as raw materials, and taking a single-atom catalyst loaded on an imidazole ester skeleton of polyacid zeolite in the application as a catalyst to prepare the levulinate through reaction.
  6. 6. The method according to claim 5, wherein the lower alcohol comprises methanol, ethanol, isopropanol or n-propanol, and the reaction condition is at a temperature of 60-110 ℃ for a time of 0.5-6 h.
  7. 7. The method according to claim 5, wherein after the reaction is completed, the system after the reaction is cooled to room temperature, the catalyst is separated by filtration, and the rest is purified by spin evaporation and gel chromatography to prepare levulinate.

Description

Polyacid zeolite imidazole ester skeleton loaded single-atom catalyst and preparation method and application thereof Technical Field The invention relates to the technical field of catalysts, in particular to a polyacid zeolite imidazole ester skeleton-supported single-atom catalyst, and a preparation method and application thereof. Background In recent years, with the rapid development of the chemical industry, there has been an increasing demand for efficient and environmentally friendly catalysts. Levulinate is an important organic synthesis intermediate and is widely applied to the fields of pharmacy, pesticides, synthetic resins and the like. The traditional levulinic acid esterification reaction mostly adopts metal catalysts, such as noble metal catalysts, and the like, and has high catalytic efficiency and good selectivity. However, these conventional catalysts generally face problems such as high cost, metal waste, and environmental pollution. The single-atom catalyst refers to a supported metal catalyst in which metal components on a carrier are dispersed in a single atom form, and is a research hot spot in the catalysis field due to unique active sites and high catalytic performance. The single-atom catalyst has the characteristic of high atom utilization rate, can obviously improve the catalytic efficiency and reduce the cost. However, to achieve stable loading of the monoatomic catalyst and maintain its activity, one of the technical problems to be solved in the prior art is still needed. In particular, the loading of a monoatomic catalyst on a carrier having a suitable pore structure to achieve effective control of the catalytic reaction and reuse of the catalyst is a hot spot problem of current research. In a single-atom catalyst taking a zeolite imidazole ester Skeleton (ZIFs) material as a carrier, the unique pore structure and good chemical stability of the ZIFs make the ZIFs become an excellent catalyst carrier material. Such materials typically have a relatively high specific surface area, can provide a large number of active sites, and can modulate catalytic performance by selecting different metal precursors. The invention discloses a glucose modified bimetallic zeolite imidazole ester skeleton derivative catalyst and a preparation method thereof, wherein the glucose modified bimetallic zeolite imidazole ester skeleton derivative catalyst is prepared by synthesizing ZIFs skeleton material under the condition of a water solvent by taking cobalt nitrate hexahydrate, zinc nitrate hexahydrate and 2-methylimidazole as reactants at room temperature, adding a trace amount of glucose for modification, wherein the molar ratio of the glucose to the 2-methylimidazole is 1 (50-60), and the molar ratio of Co (NO 3)2·6H2O、Zn(NO3)2·6H2 O to 2-methylimidazole is 2:1:8), and finally calcining the obtained precursor at high temperature. The invention discloses a bimetallic copper cobalt aza-carbon material catalyst and a preparation method and application thereof, wherein the bimetallic copper cobalt aza-carbon material catalyst adopts inorganic salt of copper, inorganic salt of cobalt, sodium formate and benzimidazole as raw materials, and N, N-dimethylformamide as a solvent, and the raw materials are dissolved in the solvent, stirred and mixed uniformly, and crystallized to obtain Cu-Co-ZIF-9, wherein the molar ratio of cobalt/copper is 10.0-50.0, and the molar ratio of benzimidazole/copper/cobalt is 2.0-8.0. Calcining Cu-Co-ZIF-9 in a hydrogen-argon mixed atmosphere to obtain the bimetallic copper-cobalt-aza-carbon material catalyst. The Chinese patent document with publication number of CN113522317A discloses a preparation method and application of a cobalt-based bimetallic sulfur/carbon catalyst derived from MOFs, and specifically, the invention adopts zeolite imidazole ester skeleton-67 (ZIF-67) as a precursor to derive layered double metal hydroxide with three-dimensional configuration so as to realize doping of a second metal ion, and then prepares a novel Fenton-like catalyst with a carbon substrate by a one-step vulcanization and carbonization method. The Chinese patent document with publication number of CN112473736A discloses a novel supported polyacid catalyst and application thereof in preparation of levulinate, and the supported polyacid catalyst is prepared from a molecular sieve Sapo-18 and a polyacid compound H 3PW12O40, and can be used for preparing levulinate by catalyzing biomass hydrolysis. The Chinese patent document with publication number of CN115888827A discloses a method for constructing a heteropolyacid@layered double metal hydroxide acid-base double-function catalyst and application thereof, wherein ZIF-based metal-organic framework materials (POM@ZIF) of pre-packaged POMs are adopted as precursors, complete conversion is realized through a one-step in-situ packaging-recombination strategy, the POM@LDH hollow acid-base double-function catalyst is constructed, the POM@LDH holl