Effect of mesoporous silica topology on the formation of active sites in copper supported catalysts for methanol decomposition

Abstract

Modified incipient wetness impregnation procedure was applied for deposition of finely dispersed CuO or metallic copper particles into ordered mesoporous silica host matrix (KIT-6 and SBA-15). This modified procedure consists of number of consecutive impregnation steps with copper nitrate solution with changeable concentration and soft drying under vacuum procedures. Nitrogen physisorption, XRD, UV–vis, TEM–EDXS, FTIR of probe molecules (CO, NO and N2) and TPR were applied for characterization of copper state in the matrix. The obtained materials were tested as catalysts in methanol decomposition. Selected catalytic experiments were carried out under very low coverage of the surface with 11C-radiolabelling methanol. In situ FTIR study of methanol decomposition was also performed. It was found that the catalytic behaviour of copper, supported on mesoporous materials, depends in a complex way on the dispersion and accessibility of copper species within the host matrix. They can be tuned by copper loading and pore topology of the support. The optimal catalytic activity in methanol decomposition is achieved at about 8 and 15wt.% copper content for the SBA-15 and KIT-6 mesoporous supports, respectively.