Control of Chain Reactions by Use of Laser Irradiation - One-step Methanol Synthesis from Methane -

点击翻译按钮获取中文摘要

The laser light is very monochromatic, powerful and sometimes in a very short pulse, which is expected to be used in order to control effectively chain reactions in chemical syntheses and some other related processes.In the present investigation, one-step synthesis of methanol from methane, and laser ignition of methanol/air premixed gases have been studied from the above view point.1. In the experimental investigation of one-step synthesis of methanol from methane, methane, O_2 and N_2O (as an effective laser light absorber) were introduced into a temperature-controllable reaction cell and were irradiated by ArF eximer laser light at 193 nm. The reaction temperature was room temperature - 300゜C, and the pressure, 300 - 600 Torr. The products were oxygen-containing species including methanol, C_2-C_3 hydrocarbons as well as CO and CO_2 Tthe methane conversion and the selectivity of methanol increased in the presence of O_2, which indicated the existence of oxidative chain reactions in favor of methanol synthesis.2. The ignition of premixed methanol/air mixtures was performed on a rectangular nozzle burner, and the necessary laser fluence for the successful ignition was determined as a function of equivalence ratio of the premixed gases. The results were analysed by use of a computer simulation. It was concluded that the laser ignition was characterized by simultaneous production of heat and radical species.The above two examples in the present research clearly showed the possibility of laser control of chain reactions in various processes.