Simultaneous Production of Hydrogen and CNTs by In-Liquid Plasma, and Its Discharge Characteristics

The plasma in liquid is generated by applying High-Frequency (HF) irradiation of 27.12 MHz or Microwave (MW) irradiation of 2.45 GHz from an electrode, namely, a monopole-antenna electrode inserted into a reactor vessel. n-dodecane, methanol, and water are used as test liquids. The glow discharge plasma can be kept in spite of atmospheric pressure due to the cooling effect of liquid itself. The light emission from the plasma changes substantially according to the behavior of the bubble. The present Chemical Vapor Deposition (CVD) process also enabled simultaneous production of hydrogen gas and the synthesis of the Carbon Nano-Tubes (CNTs) in hydrocarbon liquids. The actual production of hydrogen per unit energy by this process corresponds to approximately 1% of that by conventional steam reforming method and about 32% of that by the alkaline water electrolysis. Moreover, this process can make the solid carbon of about 14 g/h at the same time.