PRODUCTION OF METHANE FROM CARBON MONOXIDE AND CARBON DIOXIDE IN A PLASMA-CATALYTIC COMBINED REACTOR SYSTEM

Plasma-catalytic hydrogenation of CO and CO2 for producing methane was investigated with a catalyst-packed dielectric barrier discharge reactor. The characteristics of methane production from CO/H2 or CO2/H2 gas mixture were examined with bare alumina, TiO2/alumina, Ni/alumina, and Ni-TiO2/alumina under plasma and non-plasma conditions. The results obtained with bare alumina and TiO2/alumina suggest that either plasma-induced gas–phase reactions or photocatalytic reactions hardly contribute to the conversion of CO and CO2. The nonthermal plasma was found to have a promotive effect on the conversion of CO and CO2 only when nickel-loaded catalysts such as Ni/alumina and Ni-TiO2/alumina were used, implying that the nonthermal plasma serves to promote the dissociation of carbon–oxygen bonds of CO and CO2 adsorbed on the active sites of the catalysts, known as the slowest step of the reaction