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°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., CeO 2 and TiO 2 , 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. Figure 8. The effect of Cu-loading on the WGS reaction over Cu-CeO 2 catalyst at 150-360°C [91].

Medium‐temperature shift reaction (MTS, 280–340 °C) has received much attention for use in fuel processors. In this study, bifunctional Pt‐Ni/CeO2 catalysts were prepared by different Pt (0.1–0.5 %) and Ni (5–20 %) loadings, and investigated for MTS reaction. X‐ray diffraction, N2 adsorption and temperature‐programmed reduction tests were used to characterize the prepared samples. The results showed that Pt‐Ni bimetallic catalysts have higher CO conversion in comparison to Pt/CeO2 monometallic catalyst. Furthermore, the sequential synthesis method of Pt and Ni impregnation was preferred to the simultaneous one, which is due to the better Pt dispersion on catalytic surface. Steam to carbon ratio variations study showed the maximum CO conversion to be in the range of 4.5.