Active species of copper chromite catalyst in C–O hydrogenolysis of 5-methylfurfuryl alcohol

The active sites of copper chromite catalyst, CuCr2O4·CuO, were investigated for the condensed-phase hydrogenolysis of 5-methylfurfuryl alcohol to 2,5-dimethylfuran at 220 °C. The bulk and surface features of the catalyst were characterized by XRD, H2-TPR, N2 adsorption, CO chemisorption, N2O titration, NH3-TPD, XPS, and AES. Maxima of both of the potential active species, Cu0 and Cu+, occurred after reduction in H2 at 300 °C compared to 240 and 360 °C. These Cu0 and Cu+ maxima also coincided with the highest specific rate of reaction based on the surface area of the reduced catalyst. The trends of Cu0 and Cu+ observed by N2O titration and CO chemisorption were also observed qualitatively by AES. Correlations between activity and the possible active species suggested that Cu0 was primarily responsible for the activity of the catalysts.