Catalytic performance of plate-type Pd/Zn-based catalysts for steam reforming of methanol, prepared by electroless plating

Abstract

Abstract It has been reported that a Pd/ZnO catalyst, which consists of palladium and zinc oxide, shows high performance in steam reforming of methanol. By processing this granular catalyst into a plate-type catalyst, a hybrid wall-type methanol reformer with high heat resistance and high reforming performance would be constructed. In this study, such a plate-type Pd-ZnO catalyst was prepared on an aluminum substrate by electroless plating, which consisted of a displacement plating of zinc and a chemical reduction plating of palladium. The catalytic properties of the prepared Pd-ZnO catalyst for steam reforming of methanol were then investigated. The reforming properties of the prepared catalyst varied depending on the reducing agent used in the palladium plating. The plate-type catalyst prepared with a trimethylamine-borane (TMBA) as the reducing agent exhibited high reforming properties. The measurements of physicochemical properties for such plated layer proved that a PdZn alloy was formed on the surface layer. The PdZn alloy, which was thought to be the active-site of methanol reforming, formed in the plated layer when a continuous treatment of hydrogen reduction followed by oxidation was carried out prior to the reaction. In contrast, when either reduction or oxidation treatments individually were carried out prior to the reaction, little PdZn alloy was formed. The continuous treatment of hydrogen reduction followed by oxidation was thought to be an important operation in proceeding the reforming activity. In addition, the durability in reforming properties of the prepared Pd-ZnO catalyst was examined at 350 °C. The prepared catalyst was less prone to deterioration, and restored and progressed its initial performance when a reoxidation treatment was carried out on the deteriorated surface.