Plasma-enabled catalytic dry reforming of CH4 into syngas, hydrocarbons and oxygenates: Insight into the active metals of γ-Al2O3 supported catalysts

Dry reforming of CH4 (DRM) using a plasma-enabled catalytic process is an appealing approach for reducing greenhouse gas emissions while producing fuels and chemicals. However, this is a complex process that is influenced by both catalysts and discharge plasmas, and low energy efficiency remains a challenge for this technology. Here, we developed a water-cooled dielectric barrier discharge (DBD) reactor for plasma DRM reactions over supported catalysts (Ni/γ-Al2O3, Ag/γ-Al2O3 and Pt/γ-Al2O3) prepared via plasma-modified impregnation. Results show that metal loading on γ-Al2O3 enhanced the basic nature of the catalysts and promoted the formation of discharge channels and reactive species. The maximum conversion of CO2 (21.4 %) and CH4 (27.6 %) was obtained when using Ag/γ-Al2O3. The basic nature of the catalytic materials dominated CO2 conversion, whereas the properties of the catalyst and discharge plasma determined CH4 conversion. The highest selectivity of hydrogen (∼34.5 %) and carbon-containing gas products (∼81.0 %) were attained when using the noble metal catalysts (Ag/γ-Al2O3 and Pt/γ-Al2O3), while the highest total selectivity of liquid products (14.1 %) was achieved in the presence of Ni/γ-Al2O3. Compared with γ-Al2O3, the supported catalysts demonstrated higher stability, especially for Ag/γ-Al2O3 and Pt/γ-Al2O3, which also provided higher energy efficiency for gas conversion and product formation.