Effect of metal addition to Ru/TiO₂ catalyst on selective CO methanation

Selective CO methanation over Ru/TiO₂, Ru-Ni/TiO₂, Ru-Co/TiO₂, Ru-Fe/TiO₂, Ru-La/TiO₂, Ru-K/TiO₂, and Ru-Ni-La/TiO₂ was investigated as a CO removal method from reformate gas for polymer electrolyte fuel cell applications, and the selectivity and activity were examined. The addition of Co and La to Ru/TiO₂ improved both CO and CO₂ methanation, while the addition of Ni raised only the activity for CO methanation. The addition of La increased the electron density in the Ru species, which likely enhanced the dissociation of the CO bond of CO on Ru probably due to back donation of electrons from Ru to CO. This led to high CO methanation activity over Ru-La/TiO₂. The trimetallic catalyst Ru-Ni-La/TiO₂ showed the highest CO methanation activity among the prepared catalysts, resulting in a wider temperature range for selective CO methanation at low temperatures compared to Ru/TiO₂.