Insight towards the role of ceria-based supports for reverse water gas shift reaction over RuFe nanoparticles

Abstract

Utilization of CO2 through the reverse water gas shift (RWGS) reaction is a promising solution in managing greenhouse gas emissions. Here, we used the RWGS reaction to evaluate the catalytic conversion of CO2 over Ru-Fe nanoparticles supported on samarium-doped ceria (SDC) support. Catalysts of different RuxFe100-x compositions (x = 100, 80, 45, 20, 0 at.%) have been studied under steady-state conditions in a packed bed reactor in the temperature range 300–800 °C to determine their catalytic activity and selectivity towards CO. The metal-support interaction (MSI) effect for SDC was evaluated to determine its promotional behavior for the RWGS reaction. The catalyst was characterized using TEM, TGA, and ICP-ES techniques. Among all investigated catalysts, Ru45Fe55/SDC (2 wt.%) displayed the overall best activity and CO selectivity. A stability test of 100 h at 650 °C confirmed an excellent stability of the Ru45Fe55/SDC catalyst. Overall, the use of Ru45Fe55/SDC (2 wt.%) is a promising catalyst in the utilization of CO2, reaching a maximum CO yield of ∼47.5% at 800 °C and 100% CO selectivity above 500 °C. Furthermore, Ru45Fe55 (2 wt.%) nanoparticles were deposited on un-doped CeO2 and doped ceria: Gd-CeO2, Y2O3-CeO2, as well as yttria-stabilized zirconia (YSZ) and carbon supports. Contrary to carbon support, all catalysts containing oxygen conducting-ceramic supports displayed 100% selectivity to CO at temperatures above 600 °C, which can be attributed to the synergistic relationship between Ru-Fe nanoparticles being promoted through the MSI and thermally induced migration of promoting ionic species (Oδ−) from oxygen conducting ceramics to the nanoparticles.