Effect of reduction pretreatment and support materials on selective CO methanation over supported Ru catalysts

Selective CO methanation over Ru/Al2O3 and Ru/TiO2 was investigated as a CO removal method from reforming gas, and the effect of reduction treatment and the support materials on the selectivity and activity was examined. CO methanation activity was degraded over both Ru catalysts by raising reduction treatment temperature, which brought about Ru particle growth except for Ru/TiO2 reduced at 600 °C. Ru/TiO2 showed higher CO methanation activity than Ru/Al2O3 due to smaller Ru particle size. A close correlation was found between CO2 methanation rate and interfacial length of Ru particle and support, which indicates that the interface was identified as the reaction sites of CO2 methanation in CO and CO2 coexisting atmosphere. CO2 methanation over Ru/TiO2 was suppressed in spite of long length of the interface compared to Ru/Al2O3, stemming from the small amount of CO2 adsorbed onto Ru/TiO2. Ru/TiO2 catalyst exhibited wider temperature window for selective CO methanation than Ru/Al2O3 catalyst.

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► The good correlation was found between CO2 methanation reaction rate and Ru/support interfacial length.
► CO2 methanation reaction rate decreased over Ru/TiO2 that has a small amount of CO2 adsorbed, leading to increase in CO methanation selectivity.
► CO methanation activity was improved over Ru/TiO2 due to the high surface area of Ru.