Oxidative coupling of CH4 using alkali-metal ion conductors as a solid electrolyte
Abstract
The oxidative coupling of CH4 to C2H4 and C2H6(C2-hydrocarbons) has been carried out using an Li+ ion conductor as a solid electrolyte. A single-compartment cell is constructed from (Li2O)0.17(BaO)0.07(TiO2)0.76(LBT) ceramic with two gold electrodes. Alternative current voltages are applied between the two electrodes with a mixture of 8.3% CH4 and 1.6% O2 in argon. The experiments are carried out under various conditions. The formation of C2-hydrocarbons is the most effectively enhanced at a temperature of 850 °C or a frequency of 10 Hz. For example, the conversion of CH4 and the selectivity of C2-hydrocarbons at 3 V are 2 and 1.5 times more than those at the open circuit, respectively. The applications of a dc voltage to a two-compartment cell suggested that the active sites are generated via the cathodic reaction. The mechanism for the formation of C2-hydrocarbons is discussed in detail.