Preparation of palladium catalysts by pretreatment steps in electroless plating toward partial oxidation of methanol with steam reforming

A previously proposed method for depositing Ag nanoparticles on silica particles was extended to the preparation of ZnO-supported Pd (Pd/ZnO) catalysts. The method presented in this work consists of two steps: (1) Sn ²⁺ ions are adsorbed on the surfaces of ZnO particles, and (2) Pd²⁺ ions added are reduced by oxidization of Sn²⁺ to Sn⁴⁺ and simultaneously adsorbed on the surface. TEM observations revealed that Pd nanoparticles with an average size of 2-3 nm were formed on the 20 nm ZnO particles. The Pd nanoparticles were transformed into a Pd-Zn alloy by partial oxidation and steam reforming of methanol, and consequently the Pd/ZnO attained CH₃OH conversion efficiencies of 35-50% at reaction temperatures of 310-370°C.