Periodic operation applied to the kinetic study of CO2 methanation

Periodic operation was applied to CO2 hydrogenation to CH4 at 383 K on 2% Ru/TiO2. A continuous feed recycle reactor combined with a diffuse reflectance IR cell and a mass spectrometer was used to follow simultaneously the gas phase CO2 and CH4 as well as the adsorbed species. Expts. consisting of periodic variations of CO2 in the H feed showed response curves with max./min. shifted in time in the sequence CO2, (formate)x->COx->CH4. Similar delays measured for the COx formation and hydrogenation indicate that both of these processes limit the overall reaction rate. A kinetic model was proposed and verified under periodic conditions. The main exptl. trends, which are pronounced time lags between CO2, COx and CH4, could be described satisfactorily. [on SciFinder (R)]