Morphology-dependent support effect of Ru/MnOx catalysts on CO2 methanation

Abstract

Catalytic reduction of CO2 to methane constitutes an important reaction for mitigating the climate change and reducing the dependence on fossil energy resources. In this study, morphology effect of MnOx support on Ru catalysts was investigated for CO2 methanation. Significantly higher methanation rates and methane selectivities were obtained over Ru loaded on Mn3O4 hexagonal nanoplates compared to Ru supported on Mn3O4 octahedron catalysts. HR-TEM measurements revealed that the reduced RuHNS and RuONS catalyst consisted of MnO crystal phase with exposing (200) & (111) and (111) crystal facet, respectively. The CH4 yield of RuHNS was almost twice as high as RuONS, and the TOFs (Turnover frequency) calculated for these were 4.00 and 2.08 10−2S−1, respectively Moreover, as revealed by various physicochemical characterization techniques such as Raman, temperature-programmed reduction with hydrogen (H2-TPR), X-ray photoelectron spectroscopy (XPS) and temperature-programmed surface reaction with carbon dioxide (CO2-TPSR), which are responsible for the observed catalytic behavior, allowing reactants to adsorb more easily and lowering the energy barrier for both H2 and CO2. The present work highlights the importance of support morphology of Ru loaded on reducible support on CO2 methanation.