T. Wolff

Compatibility of Transport and Reaction in Membrane Reactors Used for the Oxidative Dehydrogenation of Short-Chain Hydrocarbons

The possibility of process intensification by enhancing selectivity and yield in networks of parallel and series reactions was investigated applying asymmetric multilayer ceramic and sintered metal membranes in a dead-end configuration for a controlled distributed reactant feeding. The oxidative dehydrogenation of ethane to ethylene was selected as a model reaction applying three different doped and/or active VOx/?-Al2O3 catalysts. Experimental investigations were performed in a pilot scale in order to evaluate the potential of a distributed dosing via membranes with respect to operation conditions and compatibility of reaction and membrane properties. It was demonstrated that the rates of reaction and trans-membrane mass transfer have to be compatible for an optimal membrane reactor operation avoiding back diffusion of reactants out of the catalytic zone as well as achieving safety aspects. Therefore, a detailed modeling of the trans-membrane mass transfer under reaction conditions was carried out. As a main result, it was found metal membranes possess a favorable mechanical stability, relatively low costs for production and the possibility to control mass transfer if the rate of reaction and mass transfer in the membrane is compatible which can adjusted by the trans-membrane pressure and the catalyst activity, respectively.