On-board removal of CO and other impurities in hydrogen for PEM fuel cell applications

Carbon monoxide (CO) in the hydrogen (H2) stream can cause severe performance degradation for an H2 polymer electrolyte membrane (PEM) fuel cell. The on-board removal of CO from an H2 stream requires a process temperature less than 80 °C, and a fast reaction rate in order to minimize the reactor volume. At the present time, few technologies have been developed that meet these two requirements. This paper describes a concept of electrochemical water gas shift (EWGS) process to remove low concentration CO under ambient conditions for on-board applications. No on-board oxygen or air supply is needed for CO oxidation. Experimental work has been carried out to prove the concept of EWGS and the results indicate that the process can completely remove low level CO and improve the performance of a PEM fuel cell to the level of a pure H2 stream. Because the EWGS electrolyzer can be modified from a humidifier for a PEM fuel cell system, no additional device is needed for the CO removal. More experimental data are needed to determine the rate of CO electrochemical removal and to explore the mechanism of the proposed process.