An atmospheric-pressure microwave plasma torch (APMPT) is employed to drive Boudouard reaction [C(s)+CO2(g) 2CO(g)] to convert CO2 into CO with storable chemical energy, which is available from the renewable electric energy, such as wind and solar power. In this experiment, the solid carbon is placed in the downstream of the afterglow of CO2 plasma produced by APMPT, which is enclosed in reaction chamber, thereby the reaction occurs in the environment with a plenty of the active species and the large enthalpy. The conversion rate and energy efficiency are experimentally determined by measuring the change of the gas composition, which is analyzed with a Fourier transformation infrared spectrometer (FTIR) and Gas Chromatograph (GC). The variations of conversion rate and energy efficiency are investigated with respect to the plasma state, which is tuned by changing microwave power, gas flow rate, and argon-to-CO2 mixture ratio, and the different forms of carbon material. Furthermore, the high conversion efficiency is obtained with use of the herbaceous type of biomass as carbon material and by increasing microwave power, however, the large percentage of CO2 in carrier gas and increasing gas flow rate impose a negative influence on CO2 conversion.

The atmospheric-pressure microwave plasma torch (MPT) is employed to produce hydrogen by decomposition of ethanol. The ethanol aerosol is injected directly into the early afterglow of a nitrogen plasma and the products are analyzed with Fourier Transformation Infrared Spectrometer (FT-IR) and Gas Chromatography (GC). Meanwhile, Optical Emission Spectroscopy (OES) is used to diagnose the plasma. The influencing factors on the hydrogen production are investigated with respect to the location of ethanol injection, ethanol feed rate, ethanol microdroplet size, absorbed microwave powers, total flow rate of carrier gas, and argon-to-N2 mixture ratio, respectively. And it is found that the excited species and high temperature plays the important roles in ethanol decomposition. In addition, the effect of gas flow pattern in reaction chamber on hydrogen production is analyzed with the aid of computational fluid dynamics (CFD) and the mechanism of ethanol decomposition by MPT is discussed. The achievements of hydrogen production in our experiment were reached with production rate up to 1309 L/h, energy yield up to 468 L/kWh, and hydrogen yield up to 95%, respectively.

The atmospheric-pressure oxygen microwave plasma is employed to enhance the methane combustion in the jet-diffusion combustor. The plasma-assisted combustion (PAC) is compared with natural combustion without plasma application in terms of the flame morphology, flame temperature, and combustion efficiency. It is found experimentally that the oxygen plasma assistance in combustion is prominent in lean oxygen condition, and the active species generated in the microwave plasma torch contribute to the combustion process more dominantly than the flame temperature change caused by heating of oxygen microwave plasma. The combustion degree of CH4 in PAC is much more enhanced in lean oxygen combustion, and the exhaust gas in combustion is effectively controlled with the use of the oxygen microwave plasma torch.

In this work, H2S is decomposed with use of an N2 microwave plasma torch at atmospheric pressure with the hydrogen as the main product as well as sulfur. The variation of conversion rate of H2S into hydrogen is investigated with respect to various dilution ratios of H2S in N2 carrier gas, microwave power, total flow rate, and arrangement of cooling rod in reaction chamber. And it is experimentally found that the direct cooling of the afterglow by introducing a cooled cylinder opposite to it downstream in reaction chamber takes effect in enhancement of the conversion rate of H2S to H2 and there exists an optimum for each conversion curve, which is dependent of the microwave power, gas flow rate, the relative distance of cooling rod in afterglow.

The atmospheric-pressure air microwave plasma torch is employed to assist the methane diffusion combustion with combination of the combustor and burner. Experimentally, the effect of air microwave plasma on combustion is demonstrated to be prominent in rich fuel condition by comparison of the plasma-assisted combustion (PAC) and the natural combustion (NC) without plasma application. The combustion degree of CH4 in the PAC is found to be much enhanced in rich fuel combustion than in the NC, which is measured by Fourier Transformation Infrared Spectrometer (FTIR). In the PAC with use of air microwave plasma torch, both the radicals produced in abundance and the high gas temperature induced in plasma discharge play the important role in assisting the combustion.