Methane Coupling Reaction In The Absence Of Oxygen Under The Interaction Of Ionic Liquids And Plasma

The crisis of petroleum has urged people to study on the effective exploitation and utilization of natural gas. Methane is the main component of natural gas. The traditional catalytic method of methane conversion exist high temperature and high pressure and other unfavorable factors. In the thesis, gas-liquid (Ionic liquids, ILs) plasma technology is firstly used, and the methane coupling reaction in the absence of oxygen under the interaction of ILs and plasma is reaserched. The main conclusions are shown as follows:The main products of methane conversion under a direct currnt (DC) discharge plasma are acetylene, ethylene and ethane (C2hydrocarbons). The optical emission spectroscopy (OES) of the methane and hydrogen mixtures obtain in the DC discharge plasma at atmospheric pressure contain H, CH, C2, C, and other active species. When the H2content increase, the intensity of H, CH, and C2active species increase and the intensity of C species basically unchange. When the flowrate increase, the intensity of all the active species greatly increase, and then the increased amplitude slightly decrease with the flowrate continuely increasing. The intensity of CH active specie significantly increase with discharge voltage increasing. The best conditions of the methane conversion under a DC discharge plasma are the H2content60%, flowrate45ml/min, and discharge voltage16kV. Nine imidazolium-based ILs are developed as catalysts for methane conversion under a DC discharge plasma. All nine ILs show catalytic activities for methane conversion. When the cations are the same, the ILs anions exhibit a significant effect, thus, the conversion of methane follows the order HSO4->CF3COO->BF4-. However, this effect is slowly decreased with shortening alkyl chains. In particular, HMIMHSO4shows relatively higher conversion of methane, and HMIMBF4successfully achieves90.0%selectivity for C2hydrocarbons. The acidity, viscosity, and conductivity of the ILs are important factors for methane conversion under a DC discharge plasma. The results of the OES spectra of the CH4/H2mixtures obtained in the plasma using HMIMHSO4, HMIMCF3COO, and HMIMBF4as catalysts indicate that different ILs have different effects on the intensity of the active species, the intensity of all the active species greatly increase when discharge voltage increase. ILs are favorable for methane conversion and enhance C2hydrocarbon yield. OES, FTIR, and1H NMR are obtained to confirm the stability of the HMIMBF4IL used in the plasma, and the results indicate that HMIMBF4is very stable when used in the plasma.