Design of Full-Temperature-Range RWGS Catalysts: Impact of Alkali Promoters on Ni/CeO2

Reverse water gas shift (RWGS) competes with methanation as a direct pathway in the CO2 recycling route, with methanation being a dominant process in the low-temperature window and RWGS at higher temperatures. This work showcases the design of multi-component catalysts for a full-temperature-range RWGS behavior by suppressing the methanation reaction at low temperatures. The addition of alkali promoters (Na, K, and Cs) to the reference Ni/CeO2 catalyst allows identifying a clear trend in RWGS activation promotion in both low- and high-temperature ranges. Our characterization data evidence changes in the electronic, structural, and textural properties of the reference catalyst when promoted with selected dopants. Such modifications are crucial to displaying an advanced RWGS performance. Among the studied promoters, Cs leads to a more substantial impact on the catalytic activity. Beyond the improved CO selectivity, our best performing catalyst maintains high conversion levels for long-term runs in cyclable temperature ranges, showcasing the versatility of this catalyst for different operating conditions. All in all, this work provides an illustrative example of the impact of promoters on fine-tuning the selectivity of a CO2 conversion process, opening new opportunities for CO2 utilization strategies enabled by multi-component catalysts.The authors would like to acknowledge financial support from grants PID2019-108502RJ-I00 and IJC2019-040560-I, both funded by MCIN/AEI/10.13039/501100011033, as well as from RYC2018-024387-I funded by MCIN/AEI/10.13039/501100011033 and by ESF Investing in your future. This research was also partially funded by the University of Seville via the VI PPIT grant scheme for talented researchers and the BIOALL project MSCA-RISE 2020 (grant agreement ID: 101008058)