Combustion synthesis of copper ceria solid solution for CO2 conversion to CO via reverse water gas shift reaction

Abstract

The reverse water–gas shift chemical (RWGS) reaction is a promising technique of converting CO2 to CO at low operating temperatures, with high CO selectivity and negligible side products. In this study, we investigate the synthesis of Cu/CeO2 catalyst using Solution Combustion Synthesis (SCS) technique and its performance for the RWGS reaction using a tubular packed bed reactor. Results indicate that the catalytic activity and stability of CeO2 at low and moderate temperatures can be effectively improved by the addition of a small quantity of copper (1 wt%). The conversion of CO2 improves with an increase in temperature, with a maximum value of 70% at 600 °C, showing a steady time on stream (TOS) performance for 1200 min with negligible carbon deposition of <0.05 wt%. The high catalyst activity is due to the synergistic interaction between the active Cu0 species and Ce3+-oxygen vacancy. The Cu/CeO2 catalyst was also found to have 100% selectivity for CO, and no CH4 was detected in the outlet stream. Moreover, the morphological characteristics of the support and catalysts (fresh and post-reaction samples), as well as the impact of reaction on the catalysts surface were investigated using various methods such as x-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy with energy dispersive x-ray spectra (SEM/EDX). The results demonstrate that Cu/CeO2 offers a good potential for being a robust RWGS catalyst with exclusive selectivity for CO without the undesired methanation side-reaction.