The reverse water–gas shift reaction (RWGS) offers a direct route for the conversion of CO2 into value-added CO. However, achieving high activity without promoting the competing methanation reaction remains challenging for Ni-based catalysts. Here, we report Cs-promoted Ni catalysts supported on ceria and ceria-zirconia designed to steer CO2 hydrogenation toward CO formation under conditions that thermodynamically favor methane production. Among the tested materials, 5Cs–Ni/Ce showed the most favorable balance between activity, selectivity, and stability, maintaining approximately 95% CO selectivity over 72 h at 500 ◦C. The catalyst also retained nearly complete CO selectivity under hydrogen-lean feeds down to H2/CO2 = 1, with fully reversible performance upon restoring the initial feed composition. Physicochemical characterization indicates that Cs alters the surface chemical environment of the Ni-based catalysts. Operando DRIFTS reveals that the suppression of methane formation corresponds to the strong stabilization of carbonaceous species on-top of the active metal in the presence of the alkali metal. These results identify Cs promotion as an effective strategy to decouple activity from methanation in Ni-based RWGS catalysts and provide design principles for selective CO2-to-CO conversion under practical feed conditions.
Tuning the selectivity of Ni/CeO2 and Ni/CeO2–ZrO2 catalysts for CO2 hydrogenation by caesium doping
Valentino, L.;La Parola, V.;Fortunato, M. E.;Cimino, S.;Lisi, L.;Liotta, L. F.
2026
Abstract
The reverse water–gas shift reaction (RWGS) offers a direct route for the conversion of CO2 into value-added CO. However, achieving high activity without promoting the competing methanation reaction remains challenging for Ni-based catalysts. Here, we report Cs-promoted Ni catalysts supported on ceria and ceria-zirconia designed to steer CO2 hydrogenation toward CO formation under conditions that thermodynamically favor methane production. Among the tested materials, 5Cs–Ni/Ce showed the most favorable balance between activity, selectivity, and stability, maintaining approximately 95% CO selectivity over 72 h at 500 ◦C. The catalyst also retained nearly complete CO selectivity under hydrogen-lean feeds down to H2/CO2 = 1, with fully reversible performance upon restoring the initial feed composition. Physicochemical characterization indicates that Cs alters the surface chemical environment of the Ni-based catalysts. Operando DRIFTS reveals that the suppression of methane formation corresponds to the strong stabilization of carbonaceous species on-top of the active metal in the presence of the alkali metal. These results identify Cs promotion as an effective strategy to decouple activity from methanation in Ni-based RWGS catalysts and provide design principles for selective CO2-to-CO conversion under practical feed conditions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
