Highly-selective CO2 conversion via reverse water gas shift reaction over the 0.5wt% Ru-promoted Cu/ZnO/Al2O3 catalyst

Abstract The reverse water gas shift (RWGS) reaction can be potentially used to convert captured CO 2 into renewable synthetic fuels via syngas generation. However, this conversion pathway has not been yet realized because of a number of technological challenges, including a lack of catalysts which possess satisfactory catalytic performance. In this paper, the RWGS reaction over a 0.5 wt% Ru-promoted 40 wt% Cu/ZnO/Al 2 O 3 catalyst is studied. Due to the Ru addition, CO 2 conversion was improved more than two-fold as compared to the baseline Cu/ZnO/Al 2 O 3 catalyst. The catalyst stability was significantly improved as well. Although Ru is known for its high activity in methanation reactions, the 0.5 wt% Ru-Cu/ZnO/Al 2 O 3 catalyst maintained complete selectivity to CO formation. In order to investigate this intriguing finding, the catalyst was studied by XRD, SEM-EDS, STEM-EDS, and TPR, revealing the possibility of the formation of Ru-Cu core-shell nanoparticles. Further investigation have shown that the Ru-support interaction is also a crucial factor affecting the catalyst selectivity. To extrapolate the experimentally measured data, a rate expression was derived and kinetic parameters were estimated. The resulting reaction rate expression was implemented to assess the catalyst performance under a wider range of operating conditions.