Trends in the catalytic reduction of CO2 by hydrogen over supported monometallic and bimetallic catalysts

The reduction of CO2 by hydrogen has been conducted on supported catalysts in a batch reactor. Catalysts synthesized on a reducible support (CeO2) showed higher activity than on an irreducible support (γ-Al2O3). The active metal also played an important role in controlling the selective reduction of CO2 to CO instead of CH4. Extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) confirmed the formation of uniform, bimetallic particles. Among the monometallic and bimetallic catalysts evaluated in the current study, PdNi/CeO2 was the most active bimetallic catalyst, but also formed the greatest amount of CH4, while PtCo/γ-Al2O3 showed the highest selectivity to CO with little CH4 production. The selectivity was correlated with electronic properties of the supported catalysts by using values of surface d-band center. The general trends observed should provide insights in identifying desirable catalysts for the reduction of CO2.