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.

Graphical abstractCO2 activation was studied over bimetallic and monometallic catalysts supported on both CeO2 and γ-Al2O3 to identify metallic trends and support effects. The active metal was found to control the selectivity, while the support effect dominated the activity of CO2 conversion. Metals with d-band center further from the Fermi level were more selective to CO production and catalysts supported on CeO2 were more active.Figure optionsDownload full-size imageDownload high-quality image (97 K)Download as PowerPoint slideHighlights► CeO2-supported catalysts were more active than γ-Al2O3 catalysts for CO2 conversion. ► Selectivity was correlated with surface d-band center of the metal catalysts. ► Extended X-ray absorption fine structure confirmed formation of bimetallic bonds. ► Transmission electron microscopy confirmed uniform metallic nanoparticles. ► PtCo/CeO2 appears to be the most selective catalyst for CO2 conversion.