Physicochemical properties of a plate-type copper-based catalyst, prepared on an aluminum plate by electroless plating, for steam reforming of methanol and CO shift reaction

Abstract

Abstract A plate-type copper-based catalyst was prepared by electroless plating on an aluminum substrate. Its physicochemical properties were measured to examine the relation to methanol reforming and CO shift performances. The catalytic activity of the plated copper-based catalyst was improved more by oxidation treatment in air than by reduction treatment prior to the reaction. In this case, the oxidation treatment caused the zinc located in the bulk layer to migrate to the surface and form a CuZn alloy-like compound. While, the reduction treatment made only a small amount of zinc migration, so the CuZn alloy was barely formed. The surface area of metallic copper component on the catalyst was increased by the reduction treatment, and with the number of reductions; however, there was no relationship between such metallic surface area and CO shift activity. The valence of the copper species at the surface layer was metallic after reduction treatment and cationic after oxidation treatment or reforming reaction. It was found that the presence of metallic copper species on the plated catalyst hardly contributes to the formation of active site. The formate species, which are considered as the intermediate of reforming and CO shift reaction, were adsorbed on the catalyst in the form of a monodentate-type or a bridge-type (and/or bidentate-type). On the surface that experienced oxidation treatment, the proportion of the monodentate-type formate group was higher. It was inferred that the formation of a CuZn alloy-like compound accelerates the increase of monodentate-type formate group and contributes to the improvement of catalytic activity.