Mechanistic studies of CO2/CH4 reforming over Ni-La2O3/5A

The mechanism of CO2/CH4 reforming over Ni-La2O3/5A has been studied. The r esults of the CO2-pulsing experiments indicated that the amount of CO2 conv erted was roughly proportional to the amount of H present on the catalyst, implying that CO2 activation could be H-assisted. Pulsing CH4 onto a H-2-re duced sample and a similar sample pretreated with CO2, we found that CH4 co nversion was higher in the latter case. Hence, the idea of oxygen-assisted CH4 dissociation is plausible. The fact that the amount of CO produced in 1 0 pulses of CO2/CH4 was larger than that produced in 5 pulses of CO2 follow ed by 5 pulses of CH4, indicated that CO2 and CH4 could activate each other synergistically. In the chemical trapping experiments, following the intro duction of CD3I onto a Ni-La2O3/5A sample pretreated with CH4/CO2, we obser ved CD3COOH, CD3CHO, and CD3OCD3. In the in situ DRIFT experiments, IR band s attributable to formate and formyl were observed under working conditions . These results indicate that formate and formyl are intermediates for syng as generation in CO2/CH4 reforming, and active O is generated in the breaki ng of a C-O bond. Based on these results, we suggest that during CO2/CH4 re forming, CO2 activation is H-promoted and surface O species generated in CO 2 dissociation reacts with CHx to give CO. A reaction scheme has been propo sed.