PERIODIC OPERATION APPLIED TO THE KINETIC-STUDY OF CO2 METHANATION

Periodic operation was applied to the CO2 methanation reaction at 383 K on 2% Ru/TiO2. A continuous feed recycle reactor combined with a dif fuse reflectance infrared cell and a mass spectrometer allowed to foll ow simultaneously the gas phase CO2 and CH4 as well as the adsorbed sp ecies (CO)a and (formate)a. Experiments consisting of periodic variati ons of CO2 in the hydrogen feed showed response curves with maxima/min ima shifted in time in the sequence CO2, (formate)a --> (CO)a --> CH4. Similar delays measured for the (CO)a formation and hydrogenation ind icate that both of these processes are limiting the overall reaction r ate. A kinetic model was proposed and verified under periodic conditio ns. The main experimental trends, which are pronounced time lags betwe en CO2, (CO)a and CH4, could be described satisfactorily.