Effect of coordinated ligands on catalytic properties of activated-carbon fibers-supported copper (II) complexes for the dehydrocoupling of methanol to methyl formate

Series of activated-carbon fibers-supported copper (II) complex catalysts (Cu/ACF) were prepared to catalyze the reaction of methanol to methyl formate (MF). The ligands used for the preparation of copper complexes include ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, 1,4-diaminobutane and 1,6-diaminohexane. The activities of all Cu/ACF catalysts increase with the ratio of ligand/Cu, passes through a maximum, and then decrease. The catalysts having the optimum results of methanol conversion and MF yield show different values of ligand/Cu, but show a similar UV–Vis absorption band around 700 nm. The catalytic activity of Cu(X)n2+/ACF catalyst can be adjusted by the selection and the varying of the coordination number of the ligands. The slightly reduced Cu (II) species having an absorption band around 700 nm were found to be the effective sites.