Ion Exchange Resins: Catalyst Recovery and Recycle

Chemical synthesis is greatly facilitated by catalysis and further on by catalyst recovery and recycle. Catalyst reuse increases the overall productivity and cost effectiveness of chemical transformations while minimizing their environmental impact, ultimately contributing considerably to the sustainability of chemical processes. Indeed, catalyst recycle fits most "principles of green chemistry"1-4 and was included as a priority in several strategic research agendas both in the United States and in Europe.5,6 To date, catalytic technologies leading to fine-chemicals production, and particularly in selective, large-scale processes, are still largelydominatedbyhomogeneouscatalysts, whose separation from the reaction products and reuse is a major concern. Due to the easier workup and integration in reactor equipments, the chemical industry has a strong preference for solid catalysts, which, however, usually do not provide selectivities (chemo, regio, or stereo) comparable to those observed in the homogeneous phase. There is therefore a clear need to develop new concepts bridging heterogeneous and homogeneous catalysis and to apply these to the engineering of catalytic devices for the industrial production of fine chemicals.