Interestingly, no other by-products were detected, neither in the liquid nor in the gas phase. A scheme of possible reaction mechanisms leading to by-product formation through consecutive oxidation of MEK is reported in Scheme 1. MEK, as a ketone, may undergo acetalization-like reactions with oxygen-containing compounds such as water, an equilibrium reaction that favours the ketonic form. If acetalization occurs with lattice oxygen, additional decomposition events may follow. C-C cleavage could result in the formation of a carboxylate and an alkyl fragment, inducing further MEK oxidation. Carboxylates could undergo hydrolysis, releasing the corresponding acid (either propionic or acetic acid in this case), but no such compounds were observed in our mixtures. This absence might be explained by the fact that carboxylate salt hydrolysis typically occurs in acidic conditions, and our medium is non-acidic. Consequently, the carboxylate may either bind to the surface (although no related species were observed by FT-IR which is, however, not surface specific) or undergo decarboxylation. The remaining alkyl fragments, likely bound to lattice oxygens, may undergo various desorption pathways. They could hydrolyze into corresponding alcohols or, less likely, alkanes; they could be selectively oxidized to corresponding aldehydes; or they could simply combust to form carbon dioxide and water. Given the absence of any of the mentioned compounds except CO2, the latter scenario is proposed. The experiment using MEK as the only reaction species in the feed provides more insights into this process. Despite the fact that most MEK passed through the catalyst bed unreacted, the CO2 production was significantly higher than with a 2-butanol solution feed.