Study Of Low Carbon Alkanes Conversion Using Non-equilibrium Plasma

With oil resources reducing, more attention has been paid on non-equilibrium plasma technology to converse low carbon alkanes. In this thesis, alkenes synthesis from low-carbon alkanes and amination of methane were studied by dielectric barrier discharge (DBD) plasma techonology. Based on experimental results, the additive gases (N2、He、Ar、H2、NH3、O2x CO、CO2) play an important role in conversion of low-carbon alkanes and selectivity of total alkanes. CO is the best additive gases. In order to understand the process of low-carbon alkane conversion before and after CO introduction, the discharge current waveform and OES spectrum of species existing in plasma area were studied. In the research of amination of methane, we mainly focused on the effect of different reactors (single barrier DBD, double barrier DDBD, non-barrier branch, Y and T style reactor) on the product distribution. The main conclusions are listed as following:1. In pure low carbon alkane system, the more carbon number in alkane, the easi er activation of low carbon alkane by DBD plasma. And under the same condition, i t would have a high coversion and selectivity of total alkenes.2. There is the optimum amount for different additive gases in the conversion of low carbon alkanes.80%CO exhibits the best activity, the corresponding conversion of low carbon alkanes (methane、ethane、propane) were increased by14.42%、17.61%and42.79%, the selectivity of total alkenes were increased by19.91%、25.00%and11.87%respectively.3. After introduction of CO in the system of low carbon alkanes via DBD plasma, The existence of excited O*species(777.5nm and844.7nm) has been observed in the system. Excited O*species is favorable to break C-H bond, which is beneficial for alkene’s formation. Meanwhile, electron density of plasma has been detected increase obviously through Oscillograph. Both of them maybe are the main reasons to cause CH4conversion in CH4-CO system.4. In amination of methane, the material of grounding electrode in single barrier DBD reactor has important effect on methane conversion and product selectivity. When grounding electrode is aluminum foil, it is very good for methane conversion and the selectivity of methylamine from CH4. Among the different reactors, tube-tube reactor and tube-plate reactor exhibit the highest conversion of methane, but there is no methylamine in products, which was caused by the side reaction.