A single-step method has been developed for converting methane directly into methanol, a clean-burning liquid fuel in high demand in the industrial and transportation sectors. The approach engineered by Northwestern University researchers negates the need for the extreme heat and high pressures required for current energy-intensive and carbon dioxide-emitting industrial processes.

Based on cold plasma technology, the process described in the Journal of the American Chemical Society floods the plasma with fast-moving electrons to produce a highly energized state of matter. Methane gas flows through a plasma bubble reactor — a porous glass tube coated with a copper oxide catalyst — and subjected to electrical pulses. Methane is then split into water and reactive fragments, which recombine to yield methanol, which then immediately dissolves into the surrounding water to stop the chemical reaction and prevent carbon dioxide formation.

The plasma-based bubble reactor converts methane to methanol. Source: Dayne Swearer/Northwestern University

“We’re using pulses of high-voltage electricity,” explained the researchers. “If the electrical potential is high enough, lightning bolts form inside of our reactor the way they do during a summer thunderstorm. We’re taking advantage of that chemistry to break methane’s bonds without heating the entire system to extreme temperatures.”

Under optimized conditions, the system demonstrated 96.8% methanol selectivity in the liquid mixture. The plasma-driven system could enable smaller, distributed facilities that use electricity to convert methane into liquid fuels.