Unusual roles of ceria as the support of a single-atom catalyst in hydroisomerization of n-heptane: Phase boundary acts as transport channels between different active centers

Abstract

Hydroisomerization of n-alkanes plays an important role in fuel and lubricants processing. Bifunctional catalysts with ultralow platinum loading have recently been reported successively for hydroisomerisation. Herein, the catalysts were prepared successfully with different methods to improve the catalytic performance. The conversion of 0.01%Pt1@CeOx/SAPO-11 prepared by co-calcination method (0.01%Pt1@CS-c) is 71.4%, 25% higher than the other prepared by precipitation method. The turnover frequency per active surface platinum site (TOFPt) of 0.01%Pt1@CS-c is as high as 13115 h–1. Revealed by the X-ray photoelectron spectroscopy (XPS) results, the quality of phase boundary/intersurface between ceria and zeolite is found significantly different. The conjunction quality of phase boundary directly affects the spillover rate of intermediate species, which further leads to an apparent activity difference. In addition, the possible role of ceria in the reaction is discussed, rather than just as a carrier for the active metal atoms.