Synthesis of Acetylene and Benzene in Controlled Methane-Plasma System

High-energy chemistry is a method of accelerating chemical reactions by transferring copious amounts of energy to individual molecules. The synthesis of acetylene and benzene is a valuable chemical process used in many organic products. The article proposes an original scheme of experimental setup and technology for plasma-activated methane conversion into acetylene and benzene. The system enables the creation of two distinct active zones within the reactor: the “hot zone,” where plasma and active elements are generated, and the “relaxation zone,” where the synthesis of organic products occurs. The optimal temperature of the blowing gas, i.e., the gas that propels the plasma reactor walls, has been found to be a crucial factor in heat removal from reaction zones. This temperature has been observed to vary within an interval of 290–310°K, while the reactor gas pressure has been identified as a significant variable within a range of 10–40 mbar. These two factors have been identified as the primary determinants of the yield of products, with acetylene yields reaching approximately 70–80% and maximal benzene yields reaching 40%. Furthermore, the duration of plasma exposure is a critical variable in methane conversion. The optimal acetylene yield of 80% was achieved when the reactor was operated in stationary mode for 15 s. A variation of the input gas flow in flow mode within an interval of 5–15 m³/h resulted in a decrease in the yield of acetylene to 60 percent, while an increase in the benzene yield up to 50 percent was observed. This was accompanied by an overall increase in the total volume of products produced per time unit. A general qualitative model of methane reforming is proposed, combining methane dehydration in the plasma flame with direct synthesis of acetylene from carbon and hydrogen atoms in the relaxation zone. Benzene formation occurs through the trimerization of acetylene molecules under heat dissipation near the reactor walls.