DEFINING CONDITIONS WHERE THE USE OF POROUS MEMBRANE REACTORS CAN BE JUSTIFIED SOLELY ON THE BASIS OF IMPROVED YIELD

Dehydrogenation using a porous membrane reactor is evaluated by compar ing optimized membrane reactor yields to yields from a plug-flow react or network for cases where a pressure differential is applied across t he membrane. The plug-flow reactor network is equal in size to the mem brane reactor. It uses the same amount of reactant paraffin at the sam e pressure as the membrane reactor. It uses no more inert diluent than the membrane reactor, and at the same pressure. Finally, the plug-flo w reactor network produces two product streams at the same pressures a s the membrane reactor and with the same fraction of the total hydroca rbon in each stream. Simple forms of the kinetic and reactor design re lationships, which have been demonstrated to provide an accurate descr iption of experimental dehydrogenation results, are used to model the two processes. A porous membrane reactor process offers a better yield than the plug-how reactor network only at lower conversions. In this regime a substantial fraction of the total hydrocarbons is recovered f rom the low pressure, sweep side of the process. In all comparisons th e membrane reactor is optimized only for maximum yield. (C) 1997 Elsev ier Science Ltd.