Study On Methane Conversion Via Non-thermal Plasma At Atmospheric Pressure

As the national energy strategy transition and the increase of natural gas proved reverses and output, methane conversion became the highlight of natural gas utilization. While the conventional methods of methane conversion have drawbacks such as high activating temperature and catalyst deactivation, the non-thermal plasma, which has a unique non-equilibrium character, was applied in methane conversion and attracted increasing interests.In this thesis, the methane conversion via non-thermal plasma at atmospheric pressure was studied in different reactors. It was found that different reactor had different product distribution which was attributed to the different electron energy. In the multi-tip rotary electrode reactor and glass-dielectric barrier discharge (DBD) reactor, methane was decomposed to CH and C, which resulted in the form of main product of acetylene and carbon deposition. While in the quartz-DBD reactor, methane was decomposed to CH3 which resulted in less carbon deposition and the main product of ethane. The multi-tip rotary electrode reactor showed the highest energy efficiency.The effect of different parameters in the multi-tip rotary electrode reactor and quartz-DBD tubular reactor on methane conversion was investigated, and the results showed that in the multi-tip rotary electrode reactor, the reaction duration could be prolonged by using 4-edge inner electrode and low CH4/H2 ratio. The plating materials of electrode surface showed little effect on the reaction. After carbon deposition, the electrode was cleaned by two methods and the results showed that different cleaning method showed different effect on the reaction. The scale-up of the reaction presented non-linear property and the increasing of input power resulted in the variation of discharge form, which led to the change of products distribution. While in the DBD reactor, the outer electrode material and its thickness had little effect on the reaction, but other parameters such as residence time, input power, outer electrode form, etc had great effect on the reaction. When methane flow rate was high, dielectric thickness showed great effect on the reaction. Under the same input power, the methane conversion improved with the increase of discharge voltage and the products distribution was also affected.