Membrane in a reactor: A functional perspective

Membrane reactors have found utility in a broad range of applications inclu ding biochemical, chemical, environmental, and petrochemical systems. The v ariety of membrane separation processes, the novel characteristics of membr ane structures, and the geometrical advantages offered by the membrane modu les have been employed to enhance and assist reaction schemes to attain hig her performance levels compared to conventional approaches. In these, membr anes perform a wide variety of functions, oft;en more than one function in a given context. An understanding of these various membrane functions will be quite useful in future development and commercialization of membrane rea ctors. This overview develops a functional perspective for membranes in a v ariety of reaction processes. Various functions of the membranes in a react or can be categorized according to the essential role of the membranes. The y can be employed to introduce/separate/purify reactant(s) and products, to provide the surface for reactions, to provide a structure for the reaction medium, or to retain specific catalysts. Within these broad contexts, the membranes can be catalytic/noncatalytic, polymeric/inorganic, and ionic/non ionic and have different physical/chemical structures and geometries. The f unctions of the membrane in a reaction can be enhanced or increased also by the use of multiple membrane-based schemes. This overview develops a persp ective of each membrane function in a reactor to facilitate a better apprec iation of their role in the improvement of overall process performance.