Non-Oxidative Coupling of Methane to C₂ Hydrocarbons under Above-Atmospheric Pressure Using Pulsed Microwave Plasma

Abstract

A conventional high voltage wire-like plasma can be enhanced and spread by pulsed microwave to form an umbrella-like plasma which is continuously distributed in a reactor. Using such enhanced plasma, methane was directly converted to C 2 hydrocarbons with higher yield than using conventional plasma at atmospheric or higher pressure. There was hardly any detectable trace of ethane in the product. The effects of pressure, microwave power, pulse duration, H 2 /CH 4 mole ratio, and flow rate on methane conversion were investigated. With flow rate of 300 mL/min, H 2 /CH 4 ratio of 2, pressure of 0.13MPa, peak microwave power of 120 W, pulse duty factor of 400/400 ms, conversion of methane and yield of C 2 had reached up to 59.2% and 52.1%, respectively. The ratio of C 2 H 2 /C 2 H 4 in the product could be adjusted by changing the pressure.