Highly CO-selective Ni–MgO–CexZr1–xO2 catalyst for efficient low-temperature reverse water–gas shift reaction

Abstract

High inertness of CO2 hinders its usage as a cost-effective C1 resource to produce value-added chemicals, and hence, reactive H2 are often employed for CO2 utilization. CO is a more reactive C1 building block that can be produced via the reverse water–gas shift (RWGS) reaction using CO2, but this requires a high temperature with robust catalysts that should endure the harsh endothermic conditions. Herein, Ni–MgO–CexZr1–xO2 (NMCxZ1–xO) catalysts with various Ce/Zr ratios, giving different strong metal–support interaction (SMSI) among metallic components, are investigated for low-temperature RWGS reaction to achieve high CO selectivity. The control of Ce/Zr ratios affords systematic changes in the oxygen storage capacity (OSC), acidity, and basicity, affording remarkable changes in the catalytic behaviors for CO2 conversion and CO selectivity. Among various NMCxZ1-xO catalysts, NMC0.6Z0.4O exhibited the highest resistance to change in reaction temperature, maintaining 100 % CO selectivity below 320 °C, whereas the CO2 conversion and CH4 selectivity of the other catalysts increased dramatically with increasing reaction temperature. The 100 % CO selectivity can be attributed to the high OSC and optimized balance of acidity and basicity of the NMC0.6Z0.4O catalyst, and its retention of catalytic activity owing to the SMSI among metallic components.