Effect of citric acid addition on MoO₃/CeO₂-Al₂O₃ catalyst for sulfur-resistant methanation

Citric acid hold great promise to improve the Mo-based catalyst performance for hydrogenation reaction applications. MoO₃/CeO₂-Al₂O₃ catalysts were prepared by impregnation method with adding citric acid into CeO₂-Al₂O₃ composite supports and tested for sulfur resistant methanation. The syngas methanation activity increased with the increase of citric acid additive amount, and CO conversion could reach up 60% when the molar ratio of citric acid to Ce was 3. The prepared catalysts were characterized by BET, H₂-TPR, XRD and XPS. The increased catalytic performance was mainly attributed to the increased amount of Ce species on the surface of catalysts which could decreased the interaction force between MoO₃ and CeO₂-Al₂O₃ supports. Additionally, the increased specific surface of CeO₂-Al₂O₃ composite support was also in favor of catalytic performance.