Understanding the function of support and metal loading on catalytic CO2 reduction using Ru nanoparticles supported on carbon nanofibers

Abstract

Catalytic CO2 reduction has been performed using carbon nanofibers or nitrogen doped carbon nanofibers as novel support for several Ru contents. The catalyst consisting of 5 wt% Ru on nitrogen doped carbon nanofiber exhibited the highest conversion at relatively low temperature, complete selectivity to CH4 and stable catalytic performance. The catalytic performance was substantially superior to catalysts supported on carbon nanotubes and akin to the best metal oxide supported catalyst in the literature. The characterisation of the prepared catalyst by transient experiments (CO2-TPD, TPSR and transient response to CO2 removal) revealed that the catalyst support participates actively in the reaction. The Ru content governed the selectivity, either favouring CO formation for lower Ru contents (0.5-2 wt%) or CH4 formation for 5 wt% Ru loading. The mean Ru particle size determined by TEM was similar for the several metal loadings. Therefore, the substantially different selectivity patterns cannot be attributed to structure sensitivity. The higher selectivity to CH4 can be explained by the enhanced supply of 4 Had to the activated COad intermediate, which was demonstrated to be the rate determining step. ; The financial support of European Commission (FREECATS project, FP7 Grant agreement nº 280658) from Spanish Ministry MINECO and the European Regional Development Fund (project ENE2013-48816-C5-5-R), and Regional Government of Aragon (DGA-ESF-T66 Grupo Consolidado) are gratefully acknowledged. ; Peer reviewed