Medium-Temperature Shift Catalysts for Hydrogen Purification in a Single-Stage Reactor

Interest regarding the WGS process has grown significantly, because of the recent progression in fuel cells as a clean technology for power generation. Due to the large volume and cost of WGS conventional two-stage reactors, and also problems related to pyrophoricity and lengthy reduction of customary catalysts, the current challenge is to develop more active and stable catalysts that convert CO in a single-stage medium temperature shift (MTS, 280-360 degrees C) reactor, which is applicable in small-scale fuel cells. Advanced and newly developed catalytic systems for hydrogen purification via MTS reactions are reviewed and discussed in this study. Pt-based catalysts on reducible oxide supports, e. g., CeO2 and TiO2, have mainly been used for this reaction. It is known that ceria is the most applicable active and stable support and highly promising for MTS reactions, considering its high oxygen storage capacity and mobility of surface oxygen/hydroxyl groups. New studies investigate modified ceria, e. g., CeZr, to improve its catalytic properties.