Present and Future Prospects of Hydrogen Production Process Constructed by the Combination of Photocatalytic H2O Splitting and Membrane Separation Process

Abstract

The recent research circumstances of photocatalytic overall splitting of H2O and the membrane separation of H2 and O2 for constructing the hydrogen production system by applying photocatalytic H2O splitting are introduced. Here, the principle of photocatalytic H2O splitting and photocatalysts for the reaction are explained on the historical aspect. Furthermore, the photocatalysts with high photocatalytic ability to the reaction, not only the photocatalysts and photocatalytic systems work under solar irradiation but also those show high efficiency are introduced. Incorporating gas separation membranes into the photocatalytic reactor leads to a safe and energy–efficient hydro- gen production process. Since any research of application of gas separation membrane to this purpose has not been found in the literature, our research is introduced. The goal performance that the membrane should achieve to pro- duce safe H2 and O2 streams have been determined by a simple model of a membrane module. Permeability and selectivity of H2 over O2 for silica membranes, carbon membranes, and polyimide membranes have been examined in a temperature range from 35 to 100℃. Some silica membranes have passed the goal at 100℃ for a wet mixture of H2/O2(2/1).