ALKALI METALS PROMOTED Ru/Al2O3 CATALYSTS FOR CO2 METHANATION

Alkali metals (Na, K and Li) promoted 1%Ru/Al2O3 catalysts were developed for the reaction of CO2 methanation with H2. Catalysts were prepared by introducing the alkali metal before or after ruthenium dispersion on alumina while also changing the Ru/alkali metal ratio. The Li-promoted catalyst is the best performing material showing a CO2 conversion significantly higher than that of the parent 1%Ru/Al2O3 catalyst with a high selectivity to methane. Quite good performance is also achieved using the catalyst with a relatively low NaCO3 load. On the contrary, high amounts (10%wt.) of NaCO3 or K2CO3 depress CO2 conversion mostly activating the reverse water gas shift reaction. The activity and selectivity to CH4 have been correlated with results of materials characterization highlighting the role of CO2 adsorption and carbonate decomposition.