Monomeric Copper(II) Sites Supported on Alumina Selectively Convert Methane to Methanol

Monomeric Cu-II sites supported on alumina, prepared using surface organometallic chemistry, convert CH4 to CH3OH selectively. This reaction takes place by formation of CH3O surface species with the concomitant reduction of two monomeric Cu-II sites to Cu-I, according to mass balance analysis, infrared, solid-state nuclear magnetic resonance, X-ray absorption, and electron paramagnetic resonance spectroscopy studies. This material contains a significant fraction of Cu active sites (22%) and displays a selectivity for CH3OH exceeding 83%, based on the number of electrons involved in the transformation. These alumina-supported Cu-II sites reveal that C-H bond activation, along with the formation of CH3O-surface species, can occur on pairs of proximal monomeric Cu-II sites in a short reaction time.