Electrochemical separation of hydrogen from reformate using PEM fuel cell technology

This article is an examination of the feasibility of electrochemically separating hydrogen obtained by steam reforming a hydrocarbon or alcohol source. A potential advantage of this process is that the carbon dioxide rich exhaust stream should be able to be captured and stored thereby reducing greenhouse gas emissions. Results are presented for the performance of the anode of proton exchange membrane (PEM) electrochemical cell for the separation of hydrogen from a H2–CO2 gas mixture and from a H2–CO2–CO gas mixture. Experiments were carried out using a single cell state-of-the-art PEM fuel cell. The anode was fed with either a H2–CO2 gas mixture or a H2–CO2–CO gas mixture and hydrogen was evolved at the cathode. All experiments were performed at room temperature and atmospheric pressure. With the H2–CO2 gas mixture the hydrogen extraction efficiency is quite high. When the gas mixture included CO, however, the hydrogen extraction efficiency is relatively poor. To improve the efficiency for the separation of the gas mixture containing CO, the effect of periodic pulsing on the anode potential was examined. Results show that pulsing can substantially reduce the anode potential thereby improving the overall efficiency of the separation process although the anode potential of the CO poisoned and pulsed cell still lies above that of an unpoisoned cell.