Pt Single Atom-Anchored CeOx/SAPO-11 for Highly Efficient Hydroisomerization of n-Heptane

Abstract

Single atomic catalysts (SAC) isolated in zeolite have been reported for hydroisomerization of n-alkanes. However, it is widely found that metal species located outside zeolite crystals have beneficial effects on catalytic performance, rather than inside zeolite. Herein, we introduce cerium oxide as a binder to anchor Pt single atoms on the catalyst surface. Pt species were atomically dispersed on catalyst surface certified by AC HAADF-STEM and XAS. Pt1@CeOx/SAPO-11 not only shows significant activity but also effectively inhibits the selectivity of cracking or hydrogenolysis. The turnover frequency value of 0.05%Pt1@CeOx/SAPO-11 reaches 9511 h−1, 13 times higher than reported catalyst prepared with the space-confined strategy. Reaction mechanisms have been proposed to explain the different effects of platinum status and location on the reaction. Platinum single atoms located outside the catalyst crystal are speculated more favourable to this reaction. Conceptually, catalytic efficiency of this reaction can be improved by dispersing the active sites to reduce the local concentration of the product of a reversible step in an intermediate reaction. An appropriate loading of 0.05 wt% is needed to achieve the high efficiency of the metal and acid sites simultaneously.