To observe the course of the reaction and the conversion of 2-propanol to acetone specifically, the bands at or around 1130 and 1160 cm -1 , 1421/1435 cm -1 and 1735 cm -1 corresponding to adsorbed 2-propoxide, adsorbed acetone and gaseous acetone, respectively, are used. When the 2-propoxide signals' intensity decreases, the intensity of the signal of adsorbed acetone increases first, before it starts to decrease again, while the signal of gaseous acetone increases simultaneously. This can be observed in the smaller crystallite size sample much better, because the overall signal intensity in the large crystallite size sample is lower due to the lower specific surface area most likely. The IR spectra MS concentration profiles suggest, that more adsorbed acetone is formed when more oxygen is available as the respective signal is more intense at the higher oxygen concentration and present from at least 100 °C, but more adsorbed acetone is partially or totally oxidised to H2 (used here to represent partial oxidation due to overlap of CO's MS signals with other species' fragments) and CO2 as well at higher temperatures as the intensity of the gaseous acetone's IR and MS signals are lower and the MS signals of H2 and CO2 are higher (only slightly for H2). Occasionally, it is stated, that adsorbed acetone is an intermediate taking part in the total combustion process , which is supported here by the coincidence of adsorbed acetone's IR signal decrease and the MS signal increase of CO2. At lower temperatures, the intensity of the MS signal of acetone correlates with the signal at 1421/1435 cm -1 representing adsorbed acetone more than with the signal representing gaseous acetone at around 1735 cm -1 as MS seems to be superior in sensitivity to IR spectroscopy here. At higher temperatures, especially at the maximum temperature of 400 °C, correlation between the intensity found for acetone by MS and in the IR spectra at around 1735 cm -1 correlates well: in the experiment carried out at a 2-propanol:O2 ratio of 2:1, signal intensities in both MS and IR spectroscopy are higher than in the experiment carried out at a 2propanol:O2 ratio of 1:1. Generally, the MS concentration profiles of these operando experiments differ a lot from the ones in figure recorded with the continuous flow reactor in terms of temperature onsets of acetone and hydrogen evolution, but not as much in terms of onset temperature of CO2 evolution. This might be related to the concentration double as high as in the continuous flow reactor experiments. As the presence of acetates could not be completely excluded, deactivation of the material might be the case as well, as it has already been reported for cobalt ferrite ,