Understanding the effect of Sm2O3 and CeO2 promoters on the structure and activity of Rh/Al2O3 catalysts in methane steam reforming

The role of Sm2O3 and CeO2 promoters on the structural properties and catalytic behavior of Rh/xSm2O3–yCeO2–Al2O3 catalysts during methane steam reforming (MSR) was investigated. Promoted catalysts showed higher reaction rates per surface Rh atom and improved stability compared to Rh/Al2O3. In situ X-ray absorption revealed that the structure of Rh particles in Rh/Al2O3 changes drastically during MSR, while it was stable in the presence of Sm2O3–CeO2. Sintering of the active metal phase was the main cause of deactivation. STEM images showed stronger Rh agglomeration of the unpromoted catalyst with time on stream.

Methane steam reforming on Rh/Al2O3 catalysts promoted by Sm2O3 and/or CeO2 was studied to clarify the role of the promoters on catalytic and structural properties. Promoted catalysts showed higher reaction rates and stability than Rh/Al2O3 due to the stronger interactions of Rh and the Sm2O3–CeO2 containing support, avoiding sintering of active phase.Figure optionsDownload high-quality image (90 K)Download as PowerPoint slideHighlights
► Promoters led to higher reaction rates of Rh/Al2O3 catalysts in methane steam reforming.
► EXAFS showed instability of the Rh particles when supported on unpromoted Al2O3.
► Sm2O3 and CeO2 containing supports have stronger interaction with the active phase.
► The presence of promoters avoided sintering and oxidation of the metal particles.