Cold Plasma-Prepared Ru-based Catalysts for Boosting Plasma-Catalytic CO2 Methanation

In this work, & gamma;-Al2O3 supported Ru-based catalysts were prepared by cold plasma for boosting plasma-catalytic CO2 methanation without additional heating. CO2 conversion over plasma-prepared Ru/& gamma;-Al2O3 (76.3%) was far superior to Ru/& gamma;-Al2O3-C prepared by thermal reduction (52.0%) due to the high dispersion and surface enrichment of Ru induced by plasma. CoRu/& gamma;-Al2O3 and AuRu/& gamma;-Al2O3 prepared by plasma possessed enhanced and similar plasma-catalytic CO2 methantion activity. The sizes of the metal nanoparticles are small, and the CoRu nanoparticles showed smaller size and higher dispersion than those of AuRu. The AuRu and CoRu alloys were formed in AuRu/& gamma;-Al2O3 and CoRu/& gamma;-Al2O3, and the CoRu showed higher alloying degree and surface enrichment degree. Well alloyed RuCo may reduce the free energy of hydrogen adsorption at the catalysts. Small particle size can improve their atom utilization efficiency, and surface enrichment of the active species can shorten the heterogeneous reaction from 7 to 5 steps.