Isopropanol adsorption–oxidation over V 2O 5—A mass spectrometry study

Abstract

The isopropanol adsorption–oxidation over V 2O 5 (transient study) was monitored by mass spectrometry (MS) of desorbed molecules produced over the catalyst by reactive interaction at 40, 100 and 150 °C. Then temperature programmed surface reaction (TPSR) tests were conducted to analyse the products again by MS. The acetone adsorption–oxidation was also studied at 40 °C by the same techniques. It was concluded that isopropanol molecules replace some of the water molecules adsorbed onto the V 2O 5 but do not interact with molecules of higher adsorption energies as methanol. The following products were identified by TPSR at low temperatures (<∼150 °C) variable amounts of water, isopropanol, propylene and acetone and, at ∼200–300 °C. water, CO, CO 2, isopropyl ether . Isopropanol oxidation to acetone only use oxygen from V 2O 5. In turn, CO and CO 2 desorptions are related with incomplete isopropanol oxidation to acetone, which is limited by the proportion of oxygen available in the solid. Formation of CO and CO 2 occurs at the expense of atmospheric oxygen (He impurity). For such temperatures, V 2O 5 shows acid and minima redox properties.