The oxidative dehydrogenation of cyclohexane can take place with high yield when a palladium membrane is used to divide the reactor into reaction and separation sections. In order to establish the effect of the gas flow patterns when a sweep gas is used to remove the permeated hydrogen, five ideal flow models have been analysed and compared by N. Itoh, Y. Shindo and K. Haraya of the National Chemical Laboratory, Tsukuba, Japan {J. Chem. Eng. Jpn., 1990, 23, (4), 420–426).

Concurrent, counter current, plug-mixing, mixing-plug and mixing-mixing models were considered. It was found that the highest performance was shown by the second of these, where the feed gas on one side of the palladium membrane flows in the opposite direction to the sweep gas on the other.