Search

CN-121972224-A - Palladium-polyoxometallate cluster-cluster catalyst and preparation method and application thereof

CN121972224ACN 121972224 ACN121972224 ACN 121972224ACN-121972224-A

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a palladium-polyoxometallate cluster-cluster catalyst and a preparation method and application thereof. The palladium-polyoxometalate cluster-cluster catalyst is formed by self-assembly of a sub-nano-scale Pd cluster derived from a palladium precursor and a polyoxometalate, wherein the polyoxometalate is phosphotungstic acid (PW 12 ), phosphomolybdic acid (PMo 12 ), undecidebenone-vanadium phosphoric acid (PMo 11 V 1 ), decamolybdenum-vanadium phosphoric acid (PMo 10 V 2 ) or nonamolybdenum-vanadium phosphoric acid (PMo 9 V 3 ). The invention provides a stable palladium-polyoxometalate self-assembled cluster-cluster catalyst for preparing ketone by one-pot preparation, sub-nano Pd cluster and low-temperature low-pressure high-selectivity hydrogenation.

Inventors

  • TAN HUAQIAO
  • LI TIANLU
  • SUN YUANJIE
  • LIU JIE
  • LANG ZHONGLING
  • LIU YANCHUN

Assignees

  • 东北师范大学
  • 华能国际工程技术有限公司

Dates

Publication Date
20260505
Application Date
20260106

Claims (10)

  1. 1. The palladium-polyoxometalate cluster-cluster catalyst is characterized in that the catalyst is formed by self-assembling a sub-nano Pd cluster derived from a palladium precursor and polyoxometalate, wherein the polyoxometalate is phosphotungstic acid, phosphomolybdic acid, undecidebenone-vanadium phosphoric acid, decamolybdenum-vanadium phosphoric acid or nonamolybdenum-vanadium phosphoric acid.
  2. 2. A palladium-polyoxometalate cluster-cluster catalyst according to claim 1, wherein the polyoxometalate is undecideneavanadyl phosphate, decamolybdideneavanadyl phosphate or nonamolybdideneavanadyl phosphate.
  3. 3. A method for preparing a palladium-polyoxometallate cluster-cluster catalyst based on any one of claims 1-2, which is characterized by comprising the steps of dissolving a palladium precursor and polyoxometallate in an organic solvent, adding fatty acid and fatty amine, uniformly mixing, performing a sealing heating reaction at 80-140 ℃ for 2-6 h, washing, centrifuging, and vacuum drying to obtain the catalyst.
  4. 4. The method for preparing a palladium-polyoxometalate cluster-cluster catalyst according to claim 3, wherein the organic solvent is toluene, the palladium precursor is palladium acetylacetonate or palladium acetate, the fatty acid is oleic acid, and the fatty amine is oleylamine.
  5. 5. The method for preparing a palladium-polyoxometalate cluster-cluster catalyst according to claim 3, wherein the ratio of palladium precursor to polyoxometalate to fatty acid to fatty amine in the mixed system is 0.01-0.05 mmol to 0.05 mmol to 5-7.5 mL to 0.5-3 mL.
  6. 6. The method for preparing a palladium-polyoxometallate cluster-cluster catalyst according to claim 3, wherein the centrifugation speed is 7000-10000 rpm, the time is 3-10 min, and the vacuum drying temperature is 40-80 ℃.
  7. 7. Use of a palladium-polyoxometalate cluster-cluster catalyst according to any one of claims 1-2 as a catalyst for the selective hydrogenation of phenolic compounds, characterized in that the palladium-polyoxometalate cluster-cluster catalyst catalyzes the selective hydrogenation of phenolic compounds to the preparation of ketones at 40-80 ℃ and 0.1-2.0 MPa.
  8. 8. The method of claim 7, wherein the phenol compound is unsubstituted phenol, alkyl-substituted phenol, alkoxy-substituted phenol, or halogenated phenol.
  9. 9. The application of the palladium-polyoxometallate cluster-cluster catalyst according to claim 7, wherein the organic solvent used in the catalytic reaction is n-hexane, the ratio of the catalyst to the phenolic compound is 5-20 mg:0.1-2 mmol, and the stirring speed is 500-1200 rpm.
  10. 10. The method of claim 7, wherein the reaction gas is a mixture of 5% -100% H 2 and N 2 , and the reaction vessel is flushed 3-5 times with the mixture before the reaction.

Description

Palladium-polyoxometallate cluster-cluster catalyst and preparation method and application thereof Technical Field The invention belongs to the technical field of catalysts, and particularly relates to a palladium-polyoxometallate cluster-cluster catalyst and a preparation method and application thereof. Background Lignocellulosic biomass provides renewable raw materials for sustainable production of fuels and chemicals (ACS catalyst, 2024,14, 13800-13813). Phenol is a multifunctional platform molecule with great application potential by virtue of structural diversity and reserve richness as a core component in lignin depolymerization products. However, the high oxygen content and inherent chemical stability of phenol itself have limited its application as a fuel. The phenol is converted into cyclohexanone or cyclohexanol through selective hydrogenation reaction, so that a chemical intermediate with high industrial value can be prepared, and a feasible technical path is provided for efficient utilization of phenol. The cyclohexanone is used as a key precursor of nylon-6 (caprolactam) and nylon-6, 6 (adipic acid), and is a solvent widely applied in the fields of paint, adhesives and resins (Angew, chem, int, ed., 2024,64, e 202419178), so that a high-efficiency catalytic system for preparing cyclohexanone with high selectivity in phenol hydrogenation reaction is developed, and the catalyst has important basic research significance and practical application value. In phenol hydrogenation catalytic research, metal catalysts such as Pd, pt, ru, rh, ni, co are receiving a great deal of attention because of their excellent hydrogen adsorption and activation ability (angel. Chem. Int. Ed., 2023,62, e 202214881). Among them, palladium (Pd) is considered as one of the most potent catalytically active components of the reaction by virtue of its excellent H 2 dissociation capability and tunable electronic structure. However, the process of preparing cyclohexanone by phenol selective hydrogenation relates to four-electron/proton transfer reaction, and active hydrogen species (H) with proper concentration are required to be provided on the surface of the catalyst, and the existing Pd-based catalyst has obvious technical bottlenecks that on one hand, the surface of the catalyst is easy to form too high hydrogen coverage rate, so that the generated cyclohexanone is further excessively hydrogenated into cyclohexanol, the selectivity of a target product is seriously reduced, on the other hand, noble metal clusters such as Pd and the like are easy to agglomerate in the reaction process, the loss of catalytic active sites is caused, the electronic structure of the noble metal clusters is difficult to accurately regulate and control, the dynamic balance supply of the active hydrogen species cannot be realized, and in addition, the high-efficiency interface hydrogen transmission channel is lacked, the inherent contradiction between surface hydrogen accumulation and active hydrogen continuous migration is difficult to be relieved, and the promotion of the catalytic selectivity and the stability is further restricted. Polyoxometallates (POMs) are a class of discrete metal oxygen clusters with definite structure, reversible redox properties and adjustable acidity, providing potential for solving the above-mentioned technical problems (chord. Chem. Rev., 2024,521, 216172). The oxygen-enriched surface and the high negative charge characteristic of the catalyst not only can stabilize noble metal clusters with ultra-small size and adjust the electronic structure of the noble metal clusters, but also can construct an ideal channel for the transmission of active hydrogen species. It has been demonstrated that the reaction mechanism of noble metal-POMs composite catalytic systems involves three key steps, (i) dissociation of H 2 at the noble metal cluster surface, (ii) hydrogen flooding between the noble metal clusters and POMs, (iii) selective adsorption and activation of substrates at the catalytic interface (Nano res., 2025,18, 94907437). The hydrogen overflow process is the core for regulating and controlling the distribution of hydrogen species, namely active hydrogen species generated by dissociation of noble metal clusters (especially Pd) can be transferred to the redox center of the POMs through overflow and released to a catalytic interface when the reaction is needed, so that the hydrogen coverage rate of the noble metal surface is dynamically regulated, the sufficient supply of active hydrogen is ensured, and the occurrence of excessive hydrogenation side reaction is avoided. In addition, molybdenum-based POMs have a stronger hydrogen storage capacity than tungsten-based analogues, which is more conducive to active hydrogen transfer during multiple electron/proton hydrogenation. Based on the method, the phosphorus vanadium molybdenum based POMs have high negative charge, strong reducibility and inherent catalytic activity, are