Selective oxidation of 1-propanol over magnesium oxide promoted transition metal oxide catalysts

Abstract

The selective oxidation of 1-propanol to propionaldehyde under inlets conditions of 5 vol% of O2 and 8 vol% of 1-propanol is studied in the reaction temperature range 200-500ํC. The transition metal oxide catalysts, promoted with MgO, used include V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo and W all supported on Al2O3. Pyridine adsorption and TPR technique are used to determine the acid-base property and redox property, respectively, to find the relationship between catalytic behavior and catalyst properties (acid-base and redox properties). From the catalytic reaction, it can be indicated that the catalytic oxidation over un-promoted catalysts, 8VOAl, 8FeOAl, 8CoOAl and 8ZnOAl catalysts yielded propionaldehyde more than other unpromoted catalysts. The addition of MgO to the catalysts slightly affects the over all conversion of 1-propanol and the selectivities to COx and C1-C2 products. But, significant decreases of the selectivity of propylene and increase in propionaldehyde yield were observed. Nevertheless, there is no direct proportion between the content of MgO addition and propionaldehyde yield. In addition, an appropriate combination between acid and basic sites should exist to improve the catalytic activity and selectivity.