Catalytic and non-catalytic oxidative dehydrogenation of n-butane

The thermal pyrolysis and the catalytic and non-catalytic oxydehydrogenation of n-butane were investigated. It was found that, under optimum conditions, the non-catalyzed reaction can be very efficient and selective. The effect of temperature, butane/oxygen ratio and residence time was studied and it was concluded that high selectivity in butenes can be achieved at relatively low temperatures and low butane/oxygen ratios. Conversion of n-butane up to 90%, at 580 degrees C, and 1.8 s residence time with an overall alkenes C-2-C-4 selectivity exceeding 55% were observed. Based on experimental results, it is suggested that oxygen participates in the reaction mechanism of butane decomposition not only in the initiation steps but in the propagation steps as well. Oxidative dehydrogenation was also examined in the presence of mixed oxide catalyst comprising 30 wt% V2O5 and 70 wt% MgO. It was observed that the catalyst is very active and quite selective in desirable products at reaction temperatures (540-580 degrees C), similar to those applied in non-catalytic experiments. Very promising results were obtained when n-butane and oxygen were fed over a catalytic bed (VMgO catalyst) combined in series with a void volume (post-catalytic). High conversion of n-butane was achieved with high C-2-C-4 selectivity and relatively low COx selectivity. (C) 1998 Elsevier Science B.V. All rights reserved.