Plasma Conversion of Methane and CO₂ Using a Tubular Circle-to-Plate Reactor

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For reducing amount of CO₂ emitted by acetylene production, a research on energy efficient plasma technologies for converting methane to acetylene was conducted, resulting in development of a tubular circle-to-plate (CTP) type of reactor. The CTP reactor driven by a pulsed plasma converted mixture of methane and CO₂ to acetylene, ethylene, ethane, carbon monoxide, higher hydrocarbons such as C₃ and C₄, and hydrogen. CO₂ was used mainly for stabilizing the plasma discharge, though it also reacted with methane yielding CO and hydrogen. A maximum energy efficiency of 4 mmol/kJ, which was obtained at a pulse frequency of 625 Hz, indicated a potential to reduce CO₂ emission from the acetylene production. The energy efficiency decreased at a pulse frequency above 625 Hz with the CTP reactor, which differed from results with co-axial cylindrical (CAC) and point-to-point (PTP) type reactors. Acetylene selectivity was 62% at maximum at 8 kHz.
The plasma technology would also be useful for relocating conventional fossil fuel dependent acetylene production to the sun-belt where solar thermal power, which is relatively inexpensive among renewable energies, can be utilized to generate plasma. Such relocation accompanied by replacement of fossil energy with renewable energy would result in reduction of global CO₂ emission.