Determination of the Conversion and Efficiency for CO2 in an Atmospheric Pressure Microwave Plasma Torch

Abstract

In a 2.45 GHz plasma torch, carbon dioxide (CO₂) has been converted into carbon monoxide (CO) and oxygen (O₂) at atmospheric pressure. The conversion and the efficiency of the plasma have been determined using two independent measuring methods: mass spectrometry and Fourier transform infrared absorption spectroscopy. The conversion depends on the measurement position in the exhaust gas duct. The conversion values at the beginning of the exhaust gas duct are significantly higher (maximum conversion is 22 %) than in the thermalized state at the end of the duct. In the cold, thermalized state of the gas, the maximum conversion rate is 8 % at 1.5 eV molecule⁻¹. The maximum efficiency of 25 % is achieved at approximatively 0.6 eV molecule⁻¹ operating at a microwave power of 0.48 kW and a mass flow of 12 slm CO₂.