Use of simple test reactions to characterise the catalytic activity of a commercial CoO-MoO3-Al2O3 catalyst

Abstract

Exchange of thiophene with D₂ and reactions of deuterium-labelled propene and isobutene, followed using a combination of mass spectrometry and microwave spectroscopy, have been used to characterise the catalytic nature of a commercial CoO-MoO₃-Al₂O₃(CMA) catalyst. The results indicate that the activity of partially sulphided CMA, produced by exposure to H₂S or by hydrodesulphurization (h.d.s.) of ethanethiol, closely resembles that of unsupported MoS₂. Thus, sulphided-CMA shows high selectivity/activity for exchange of the α hydrogens in thiophene and catalyses double bond migration in propene through half-hydrogenated intermediates, activity characteristic of MoS₂, whereas oxide-CMA is much less active for α exchange and shows Lewis acid type activity for the latter reaction. It appears that a CMA catalyst during h.d.s. may usefully be described as “dual-functional”, with MoS₂ supported on, and stabilised by, an acidic support.