Rational H2 Partial Pressure over Nickel/Ceria Crystal Enables Efficient and Durable Wide-Temperature-Zone Air-Level CO2 Methanation

Graphical This study investigated the impact of H 2 /CO 2 partial pressure ratios on CO 2 methanation using Ni/CeO 2 . Results show elevated H 2 /CO 2 ratios enhance CO 2 conversion and CH 4 selectivity, achieving complete methanation at 250 °C and 100 % selectivity at 400 °C. In-situ DRIFTS analysis indicates formate pathway dominance at higher ratios, key for CH 4 production and CO 2 mitigation strategies. On the way to carbon neutrality, directly catalyzing atmospheric CO 2 into high-value chemicals might be an effective approach to mitigate the negative impacts of rising airborne CO 2 concentrations. Here, we pioneer the investigation of the influence of the H 2 /CO 2 partial pressure ratio (PPR) on air-level CO 2 methanation. Using Ni/CeO 2 as a case catalyst, increasing H 2 /CO 2 PPR significantly improves low-temperature CO 2 conversion and high-temperature CH 4 selectivity, i. e., from 10 of H 2 /CO 2 PPR on, CO 2 is completely methanized at 250 °C, and nearly 100 % CH 4 selectivity is achieved at 400 °C. 100-hour stability tests demonstrate the practical application potential of Ni/CeO 2 at 250 °C and 400 °C. In-situ DRIFTS reveal that reinforced formate pathway by increasing H 2 /CO 2 PPR is responsible for the high CH 4 yield. In contrast, even though the CO pathway dominated CO 2 conversion on Ni is enhanced by rising H 2 /CO 2 PPR, but at a high reaction temperature, the promoted CO desorption still leads to lower CH 4 selectivity. This work offers deep insights into the direct air-level CO 2 resourceization, contributing to the achievement of airborne CO 2 reductions.