APCATA 486-2014-115

Methanation of carbon dioxide on metal-promoted mesostructuredsilica nanoparticles

Metal-promoted mesostructured silica nanoparticles (MSN) have been studied for CO2methanationunder atmospheric pressure. In term of activities, high activity was observed on Rh/MSN, Ru/MSN,Ni/MSN, Ir/MSN, Fe/MSN and Cu/MSN at and above 623 K. However, on an areal basis, Ni/MSN was themost active catalyst, while Ir/MSN was the poorest catalyst. The catalysts have also been studied for elu-cidation of the role of each metal, MSN and metal/MSN in CO2methanation by in situ FTIR spectroscopystudies. Firstly, CO2and H2was adsorbed and dissociated on metal sites to form CO, O and H atoms,followed by migration onto the MSN surface. The dissociated CO then interacted with oxide surfaces ofMSN to form bridged carbonyl and linear carbonyl, while the presence of H atom facilitated the formationof bidentate formate. These three species could be responsible for the formation of methane. However,the bidentate formate species could be the main route to formation of methane. MSN support has beenfound to play an important role in the mechanism. MSN support served the sites for carbonyl specieswhich act as precursors to methane formation. These results provided new perspectives in the catalysis,particularly in the recycling of CO2.