Pt/CeO2 with residual chloride as reusable soft Lewis acid catalysts: Application to highly efficient isomerization of allylic esters

Abstract

Heterogeneous acid and base catalysts play a crucial role in many important chemical processes. Hard Lewis and Brønsted acid catalysts like silica-alumina and zeolites have been widely applied in numerous reactions; however, developing reusable and active soft Lewis acid catalysts remain a challenge. Herein, we demonstrate for the rst time that a highly dispersed supported platinum catalyst can act as a heterogeneous soft Lewis acid. High turnover numbers and reusability were observed in the isomerization of allylic esters under solvent-free conditions. Moreover, the as-prepared catalysts are characterized by Xray photoelectron spectroscopy (XPS) and X-ray absorption ne structure (XAFS) analyses, revealing that the highly dispersed Pt clusters with Pt-Cl bonds play a key role in the high activity. The residual chloride anion enhances the Lewis acidity of the Pt metal center and thus improves the catalytic activity. Simultaneously, the high catalytic activity of Pt/CeO 2 with residual chloride and the soft Lewis acid mechanism are also proved by density functional theory (DFT) calculations based on the model reaction.

Deoxydehydration of Biomass‐Derived Polyols Over Silver‐Modified Ceria‐Supported Rhenium Catalyst with Molecular Hydrogen

“…A recent study has showed that 3,4-diacetoxy-1-butene (diester of 3-butene-1,2-diol) can be isomerized to the equilibrium mixture of diacetoxybutenes over noble metal catalysts such as Pt/CeO 2 . [64] However, our results of the reaction of cis-2-butene-1,4-diol with very low selectivity to 3-butene-1,2-diol rather suggested the direct conversion to 1,3-butadiene without initial isomerization to 3-butene-1,2-diol. Then, we carried out density functional theory (DFT) calculation of the reactions of butenediols, erythritol, and 1,2-butanediol over the surface of reduced ReO x /CeO 2 , which is the main active site for DODH reaction (Table S8 and Figure S2; calculation details and the results are described in the Supporting Information).…”

Oxygen vacancy enhanced catalytic activity in a Pt nanoparticle decorated GO–CexOycatalyst for the efficient synthesis of pyran based derivatives

“…In addition, the increase in surface area after modification with GO could be due to the reduction of oxygen containing functional groups on GO surface. 50 Meanwhile, after decoration with Pt nanoparticles on GO–Ce x O y , the surface area decreased, which could be due to blocking of the pores. 51,52 In addition, the increase in the surface area of GO after decoration with Ce x O y is due to disorder in the structure of the GO surface.…”

Aggregation of CeO2 particles with aligned grains drives sintering of Pt single atoms in Pt/CeO2 catalysts

“…Platinum-group-metals (PGMs) on oxide supports serve as active sites in heterogeneous catalysts with applications ranging from three-way catalysts to oil rening. [1][2][3][4][5][6][7][8] The cost and scarcity of PGMs require that the metals should be nely dispersed on oxide supports to maximize metal utilization efficiency. CeO 2 is a widely used support material, 9 because PGM dispersions of 100% can be obtained on CeO 2 .…”