DEVELOPMENT OF MEMBRANE-SUPPORTED REACTIO N PROCESSES

The use of membrane technology is developping from the solely work-up of product and waste streams all the way to integration into processes , The membrane reactor offers, by analogy with biological cells, great possibilities for product-integrated environmental protection. Two pr incipal areas of application of membranes in reactors are becoming app arent, Use for removal of products or by-products from bioreactors aci d the coupling with chemical reactions considered in this article. The first such membrane reactors served for the removal of water from est erification reaction mixtures, Significant advances for membrane react or technology came with the recent development of membranes of enhance d selectivity and flow density as well as improved thermal and chemica l stability. In addition to the availability of high-performance membr anes, fundamental knowledge and methods are required to assure efficie nt reaction-engineering utilization of membrane reactors. This paper d iscusses fundamental concepts relating to the use of various membrane reactors in parallel, consecutive, and equilibrium reactions. In gener al, in the case of membrane-supported parallel reactions, controlled a ddition of reactant can raise the reaction selectivity. Selective remo val of primary and side products from consecutive or equilibrium react ions can increase yields. Comparison of membrane-supported reactor typ es (batch, loop, and plug-flow membrane reactors) indicate that the me mbrane-supported loop reactor will prove most effective in the majorit y of cases thanks to its pronounced flexibility.