Modulating selectivity in CO2 Methanation through Rhodium catalysts supported on Zirconia-Chemically grafted SBA-15

This study presents the impact of ZrO2 2 incorporation on Rh-supported SBA-15 catalysts for CO2 2 hydrogenation. ZrO2 2 was chemically grafted onto the SBA-15 surface, varying concentrations of ZrO2 2 from 5 to 20 wt.%. The ZrO2-free 2-free catalyst favored CO production, leaning towards the reverse water gas shift reaction. The addition of ZrO2 2 notably enhanced catalytic activity and led to a significant shift in selectivity towards methane production. The selectivity modulation is linked with the modified surface of SBA-15, covered with a ZrO2 2 phase. The FTIR characterization under reaction conditions evidenced Rh-carbonyls formation in all samples. However, in catalysts materials with ZrO2, 2 , formate species are also formed, probably promoted by the Zr-OH groups. A linear relation between formate species and the CH4 4 selectivity suggests that the methane formation could be associated with the hydrogenation of formate species, while the desorption of carbonyls on Rh can explain the CO generation.