Conversion of methane to methanol by an impulse discharge on the surface of water

Summary form only given. Conversion of methane to methanol is established by using an impulse discharge on the water surface. Methane and water vapor are decomposed in the discharge to form methyl, hydroxyl, and oxygen radicals, which would react for methanol synthesis. The purpose of this study is to clarify the reaction process for an efficient generation of methanol from methane by controlling the discharge parameters. The discharge is generated between a stainless pipe electrode and a grounded needle electrode by feeding pure methane. The needle is placed in the water and its tip is adjusted to be just 1 mm below the surface of water, in order to suppress a spread of the discharge on the water surface. The position of the needle was automatically maintained by a float attached to the needle. Impulse voltage with one single sinusoidal waveform of 10 μs is applied to the pipe electrode with repetition frequency of 20 kHz. Gas components before and after the discharge were analyzed by FTIR. A production of methanol from methane is observed, together with production of ethane, ethylene, acetylene, and carbon monoxide, depending on the discharge parameters. Decomposition ratio of methane, selectivity of methanol, and energy efficiency for methane production were 51.5 %, 22 %, and 0.136 L/kWh, respectively, at methane flow rate of 1 sccm. The maximum value of energy efficiency was 0.193 L/kWh at methane flow rate of 10 sccm. Water surface discharge system developed here is quite simple and effective for the methanol production from methane and water vapor.