Membrane assisted fluidized bed reactors:: Potentials and hurdles

Recent advances in the development of more stable membranes with increased permeance have significantly enhanced the possibilities for integrating membranes into catalytic reactors in order to achieve a major increase in reactor performance by process integration and process intensification. Several reviews and even special issues of catalysis related journals illustrate the significant progress in the field of inorganic membrane reactors within the last two decades. Chemical engineers and material scientists have joined forces and addressed this topic from various view-points. In spite of their considerable efforts in these directions, the application of the membrane reactors, especially packed bed membrane reactors, in commercial processes has been very limited because of technical as well as economical drawbacks. The most recent trend in membrane reactor technology has been in the direction of incorporating inorganic membranes into fluidized beds to combine the perm-selective and controlled dosing capabilities of membranes with excellent gas-solid contact and heat transfer capabilities of fluidized beds, thereby overcoming the limitations often prevailing in packed bed membrane reactors. The opportunities for this novel fluidized bed membrane reactor compared to conventional reactors and packed bed membrane reactors have never been systematically reviewed before. This paper seeks to review literature and new developments in the area of membrane assisted fluidized bed reactors, with special emphasis on possible applications, integration of different membranes in the fluidized beds, reactor modelling studies, experimental demonstration of various reactor concepts and future prospects and hurdles for commercialization. Finally, an assessment of the state of the art has been given and directions for future research are indicated. (c) 2006 Elsevier Ltd. All rights reserved.