Abstract
A wall reactor system, in which a metallic wall is directly catalyzed, is a reaction system that enables an efficient transfer of thermal energy, a rapid response to fluctuating loads. Application of the system in a reactor involving reformers and water gas shift converters for power generator system by fuel cells is expected. In order to develop a high-performance plate-type catalyst for wall-type methanol reformer and CO shift converter, a structured copper-based catalysts were prepared by electroless plating, consisting of a displacement plating of zinc, an intermediate chemical plating of various metals, and a chemical plating of copper. The reforming and shift performances and the physicochemical properties of the plated catalysts were investigated. Results showed that the prepared catalysts had different performance depending on the metal species used in the intermediate plating. Among them, a plate-type Cu-Fe/Zn catalyst on an intermediate iron plating exhibited high reforming and shift performances. The performances of the Cu-Fe/Zn catalyst made much progress by pre-oxidizing in air stream before reaction, which were nearly the same and/or higher with that of a commercial granular catalyst. Characterization including an X-ray diffraction (XRD) suggested that the oxidation treatment produced a copper-zinc alloy on the plated surface where zinc atoms existed in proximity of copper atoms. The existence of copper and zinc atoms in proximity might have formed an active site that accelerated the formation and decomposition of an intermediate species in both reactions, which led to the increased catalytic activity. It was also demonstrated that the declined activity of the Cu-Fe/Zn catalyst was repeatedly recovered by oxidizing, which is practically convenient in using the Cu-Fe/Zn catalyst as a plate-type catalyst for a wall-type methanol reformer and shift converter.
