Dry reforming of methane over a Ni/Al₂O₃ catalyst in a coaxial dielectric barrier discharge reactor

A coaxial double dielectric barrier discharge (DBD) reactor is developed for plasma-catalytic conversion of CH 4 and CO 2 into syngas and other valuable products. A supported metal catalyst (Ni/Al 2 O 3 ) reduced in a methane discharge is fully packed into the discharge region. The influence of the Ni/Al 2 O 3 catalyst packed into the gas gap on the electrical characteristics of the discharge is investigated. The introduction of the catalyst pellets leads to a transition in discharge behaviour from a typical filamentary microdischarge to a combination of spatially limited microdischarges and a predominant surface discharge on the catalyst surface. It is also found that the breakdown voltage of the CH 4 /CO 2 discharge significantly decreases when the reduced catalyst is fully packed in the discharge area. Conductive Ni active sites dispersed on the catalyst surface contribute to the expansion of the discharge and enhancement of charge transfer. In addition, plasma-catalytic dry reforming of CH 4 is carried out with the reduced Ni/Al 2 O 3 catalyst using a mixing ratio of CH 4 /CO 2 = 1 and a total flow rate of 50 ml min −1 . An increase in H 2 selectivity is observed compared with dry CH 4 reforming with no catalyst, while the H 2 /CO molar ratio significantly increases from 0.84 to 2.53 when the catalyst is present.