Oxygen vacancies enriched Ni-Co/SiO2@CeO2 redox catalyst for cycling methane partial oxidation and CO2 splitting

Redox catalysts play a vital role in the interconversion of two significant greenhouse gases, CO2 and CH4, via chemical looping methane dry reforming technology. Herein, a series of transition metals-alloyed and core-shell structured Ni-M/SiO2@CeO2 (M = Fe, Co, Cu, Mn, Zr) redox catalyst were fabricated and evaluated in a gas-solid fixed-bed reactor for cycling CH4 partial oxidation (POx) and CO2 splitting. The catalysts are composed of spherical SiO2 core and CeO2 shell, and the highly dispersed Ni alloy nanoparticles are the interlayer between core and shell. The oxygen vacancy concentration of Ni-M/SiO2@CeO2 followed the order of Co > Cu > Fe > Mn > Zr, and Ni alloying with transition metals significantly enhanced oxygen storage capacity (OSC). Ni-Co/SiO2@CeO2 catalyst with abundant oxygen vacancies and a high OSC showed the lowest temperatures of CH4 activation (610 degrees C) and CO2 decomposition (590 degrees C), thus demonstrating excellent redox reactivity. The catalyst exhibited superior activity and structural stability in the continuous CH4/CO2 redox cycles at 615 degrees C, achieving 87% CH4 conversion and 83% CO selectivity. The proposed catalyst shows great potential for the utilization of CH4 and CO2 in a redox mode, providing a new sight for design redox catalyst in chemical looping or related fields.(c) 2023 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.