ABSTRACT
Nowadays, membrane technology is consolidated within different industrial fields. Thus, membrane processes involve a wide range of applications wherein the membrane plays the role of a selective barrier, a catalyst support, or a non-dispersive phase contactor. Processes using membranes can be designed to be cleaner and safer than conventional separation techniques, providing relatively low investment costs. Simultaneously, ionic liquids (ILs) represent an interesting alternative to conventional solvents and catalysts. However, the separation and purification of products from the IL phase can be a drawback to overcome. Conventional separation processes show some drawbacks mainly represented by the large requirements of energy and chemicals. Thus, membrane processes could be considered a competitive alternative to obtain the reaction products from an IL phase or a reaction system using ILs with high selectivity.
In this framework, this chapter describes the recent progress in catalytic systems using ionic liquids coupled to membrane processes or the use of catalytic membranes based on ILs. A summary of the applications and preparation methods of ionic liquid membranes (ILMs) is followed by a description of processes where ionic liquids are used as homogeneous, heterogeneous, and biological catalysts or catalyst support. In this way, the presence of ILs as solvent or support can improve the selectivity, stability, and activity of the catalyst.
Biocatalytic processes, developed in ionic liquids and their coupling to membrane techniques, are described in a separate section taking into account their specific reaction mechanisms and their focus in green chemistry with large potential for novel applications. Finally, the last section describes some studies on the combination of membrane processes with ILs and supercritical fluids in order to show the advantages when biphasic IL/supercritical carbon dioxide systems are considered to improve selectivity and separation efficiency, obtaining solvent-free products.
