Study On The Hydrogen Production By Microwave Discharge Plasma In Liquid

In recent years, with the rapid depletion of fossil fuels and environmental pollution becoming more and more serious. Hydrogen possesses the advantages of high calorific value, renewable and no pollution, has attracted the attentions of people all over the world. Because of the traditional hydrogen production technologies have some problems like high reaction temperature, high energy consumption and depending on fossil fuels seriously. A new hydrogen production technology-plasma method, which can be carried out at the conditions of ambient temperature and pressure, without a catalyst, is becoming the research hotspot of domestic and foreign experts.The hydrogen production by liquid microwave plasma technology in this experience is based on the first time we have realized microwave discharge in liquid in China, and then going on the further study. Our topic is unique and novel, working in the front of the world. In this study, we used the ethanol as raw material and investigated the effect of microwave power, ethanol volume fraction, reaction pressure, solution conductivity, inner electrode material on the flow rate and energy consumption of hydrogen production. At the same time, we used the mass spectrometry, gas chromatography measure the gas component, also, we monitored the species and intensity of main radicals by the emission spectrum in the experience, and got the following conclusions:The main gas products of ethanol decomposition by liquid microwave plasma are H2 and CO, besides, there are some C2H2、CH4 and CO2. In the hydrogen production process, enhancing the microwave power and ethanol volume fraction is obviously benefit for improving the hydrogen flow rate and decreasing the energy consumption. However, with the increase of ethanol volume fraction, the percentage of hydrogen is decline. The solution conductivity and reactor pressure have a significant effect on plasma excitation and maintain, which determine the microwave power input and loss, and thus indirectly affect the hydrogen production. In our result, the maximum hydrogen flow rate is 357mL/min, hydrogen percentage is 64.68%, and the lowest energy consumption is 8.00kWh/m3.The result of emission spectrum shows that there are some active species like OH·、 H·、C2、CH and O· generate by the microwave discharge in alcohol, in this process, ethanol molecules is decomposed by the high energy electrons, and then recombine to H2, CO, CO2 and other hydrocarbons through the radical reactions, H-is the key radical in hydrogen production. The electron excitation temperature in this process is about 6112-4950K, pressure in the reactor is range 13.8kPa from 19.3kPa. Depending on the result of gas product and their molar ratio, we speculate the main reaction equation may be 2C2H5OH�'5H2+2CO+C2H2.