Insights into reverse oxygen spillover effect induced via CeO2 modulation to enhance the stability of CuCoOx catalysts in hydrodeoxygenation of biomass derivatives

Abstract

In hydrodeoxygenation (HDO) reactions, the evolution of the chemical states of active species in the catalyst caused by the spillover effects greatly influences their catalyst performance. Herein, the HDO of guaiacol (GUA) over CuCoOx and CuCoCeOx catalysts synthesized by co-precipitation method was systematically investigated. During the HDO reaction of GUA, acid sites (Co(II)) facilitated the C-O bond (demethylation via -OCH3) cleavage, which was the rate-determining step. A series of characterizations and experimental results revealed that introducing CeO2 into the CuCoOx catalyst could enable the catalyst to undergo reverse oxygen spillover in the hydrogenation environment, promoting the regeneration of CoO in the catalyst. Therefore, the deactivation of the CuCoOx catalyst due to hydrogen spillover leading to CoO reduction could be avoided, and the catalyst stability improved. The present study methodically investigated the spillover effects induced by Cu and CeO2 and provided the theoretical basis for the structural design of heterogeneous catalysts.