Plasma Catalytic Conversion of CH₄ to Alkanes, Olefins and H₂ in a Packed Bed DBD Reactor

Methane is activated at ambient conditions in a dielectric barrier discharge (DBD) plasma reactor packed with Pd on γ-alumina catalyst containing different loadings of Pd (0.5, 1, 5 wt%). Results indicate that the presence of Pd on-alumina substantially abates the formation of deposits, leads to a notable increase in the production of alkanes and olefins and additionally improves the energy efficiency compared to those obtained for the non-packed reactor and the bare γ-alumina packed reactor. A low amount of Pd (0.5 and 1 wt%) favors achieving a higher production of olefins (mainly C ₂H ₄ and C ₃H ₆) and a higher yield of H ₂. Increasing Pd loading to 5 wt% promotes the interaction of H2 and olefins, which consequently intensifies the successive hydrogenation of unsaturated compounds, thus incurring a higher production of alkanes (mainly C ₂H ₆ and C ₃H ₈). The substantial abatement of the deposits is ascribed to the role of Palladium in moderating the strength of the electric and shifting the reaction pathways, in the way that hydrogenation reactions of deposits' precursors become faster than their deposition on the catalyst.