Long-Chain Hydrocarbons from Nonthermal Plasma-Driven Biogas Upcycling

The burgeoning necessity to discover new methodologies for the synthesis of long-chain hydrocarbons and oxygenates, independent of traditional reliance on high-temperature, high-pressure, and fossil fuel-based carbon, is increasingly urgent. In this context, we introduce a nonthermal plasma-based strategy for the initiation and propagation of long-chain carbon growth from biogas constituents (CO₂ and CH₄). Utilizing a plasma reactor operating at atmospheric room temperature, our approach facilitates hydrocarbon chain growth up to C40 in the solid state (including oxygenated products), predominantly when CH₄ exceeds CO₂ in the feedstock. This synthesis is driven by the hydrogenation of CO₂ and/or amalgamation of CH_x radicals. Global plasma chemistry modeling underscores the pivotal role of electron temperature and CH_x radical genesis, contingent upon varying CO₂/CH₄ ratios in the plasma system. Concomitant with long-chain hydrocarbon production, the system also yields gaseous products, primarily syngas (H₂ and CO), as well as liquid-phase alcohols and acids. Our finding demonstrates the feasibility of atmospheric room-temperature synthesis of long-chain hydrocarbons, with the potential for tuning the chain length based on the feed gas composition.