Effect of a Second Promoter on the Performance of a Potassium Doped Silica-Supported Cobalt Catalyst During CO₂ Hydrogenation to Hydrocarbons

In this study, the promoting effects of ruthenium, palladium, and copper on the performance of a 15%Co-1%K/SiO₂ catalyst were evaluated during CO₂ hydrogenation in a fixed-bed reactor. Reactions were carried out at atmospheric pressure and 270 °C with H₂/CO₂ ratio of 3. All catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and temperature-programmed reduction (TPR). Ruthenium, palladium and copper facilitated the reduction of cobalt oxides and increased cobalt dispersion. In terms of catalyst’s performance, ruthenium addition led to increased CO₂ conversion and methane selectivity with a detrimental effect on C₅₊ hydrocarbons. Palladium also presented a similar pattern at lower loading but a drop in CO₂ conversion and increased reverse water–gas shift activity were observed at 3 wt % Pd loading. Promoting with copper resulted in decreased activity, methane selectivity and C₅₊ hydrocarbons productivity with a much higher CO selectivity.