| Methane is a principal component of natural gas. With the lack of crude oil resources in the world, the development of methane utilization as the feedstock, instead of crude oil, for the production of chemical has been extensively studied. The oxidative coupling of methane (OCM) to C2 hydrocarbons is an attractive process for its potential industrial foreground. Although the OCM reaction over metal oxide catalysts by oxygen is effective, as shown that the oxidation products, CO: is unavoidable. In this regard, the oxidative coupling methane using CO: as a mild oxidant is becoming active. The conversion of methane is lower than that using 0: The difficulty in effective conversion is due to the high dissociation energy of methane and carbon dioxide.The pulse corona plasma represents a novel technology for generating a highly non-equilibrium cold plasma in which conditions the electron temperature is very high but the ionic or molecular temperature is low. So the great advantages of pulse corona plasma is that less energy goes into heating the gas at atmospheric pressure. In this paper, pulse corona plasma has been used as a new method for direct conversion methane into C: hydrocarbons using CO2 as an oxidant under low temperature and atmospheric pressure. First, the synergism of plasma and various catalysts in the reaction of CEU and CO2 was studied. Then, the reaction mechanism involved in CH4 and CO: reaction under pulse corona plasma was discussed. The main results are summarized as following:1. The reaction of CH4 and CO2 can be driven by means of pulse corona plasma without any catalyst. The main gaseous products consisted of C: hydrocarbons (C2H2, C2H6 and C2H4), CO and H2. Some little liquid products, such as water and liquid hydrocarbons were found in this reaction. The effects of reactor configuration, the ways of feed inflow and the composition of feed on the reaction were investigated. The conversion of CH4, CO2 and the yield of C2hydrocarbons, CO increased with increasing energy density, The yield of C2 hydrocarbons of 8.6%~20.6% with a methane conversion of 26.0%~43.6% and a carbon dioxide conversion of 17.8%~58.4% at energy density 800kJ/mol~2200 kJ/mol had been received.2. The synergism of plasma and various catalysts on the reaction of CH4 and C02 was investigated. Some metal oxide catalysts had high €2 yield. The order of four catalysts activities is: La2O3/Y-Al2O3> CeO2/Y-Al2O3> Na2WO4/y-Al2O3>BaO/Y-Al203. The largest C2 yield was obtained (18.1%) when using La2O3/Y-Al2O3 as catalyst at energy density 1300kJ/mol. The yield of C2 increased 5.4% than that in plasma without any catalyst. The Pd/Y-Al2O3 catalyst shows high C2H4 selectivity, C2H4 accounted for 77% of the carbon distribution of C2~C3 hydrocarbons under plasma and Pd/Y-Al2O3 catalyst loaded 0.01% Pd.3. The Pd- La2O3/Y-Al2O3 is an excellent catalyst for direct conversion CH4 and CO2 into C2H4 under pulse corona plasma. The optimum loading of Pd and La2O3 is 0.01% and 5% respectively. The effect of various factors including the composition of feed, space velocity and input power on the reaction of CH4/CO2 were investigated in detail with Pd- La2O3/Y-Al203 catalyst under plasma. The results indicate that formation C2 hydrocarbons are favored when the feed flows from plasma area to plasma-catalyst area. The activation method of plasma-catalyst shows the highest C2 hydrocarbons yield and energy efficiency than that catalytic method or plasma method. The reasons of coke formation were analyzed by TG as well as X- ray diffraction technique.4. Some active species, such as CH, C, C2, CO2 and CO, were determined by optical emission spectroscopy at the range of 250nm~670nm wavelengths. According to the active species and products of reaction, the possible pathwaysof reaction were established for CH4 and CO2 conversion under pulse corona plasma. New pathways for C2H2 and CO formation were suggested.5. Pulse corona plasma was used as an active method fo...
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