Synergy between homogeneous and heterogeneous catalysis

Abstract

Catalysis plays a decisive role in the advancement of sustainable processes in chemical, pharmaceutical, and agrochemical industries as well as petrochemical, material, and energy technologies. Notably, more than 80% of all chemical products involve catalysis processes in at least one stage in their manufacture. Thus, for the modernization of chemical synthesis, the applicability of catalysts is crucial. Since the beginning of catalysis, a large number of both homogeneous and heterogeneous catalysts have been developed and applied for all kinds of synthetic reactions. Among these, homogeneous complexes are active and selective but not stable and they are difficult to recycle or reuse. On the other hand, heterogeneous materials are quite stable and conveniently recyclable, but they exhibit lower activity and selectivity. In catalysis, the development of ‘ideal’ catalysts, which should be more active and selective as well as stable and easily recyclable, is of prime importance to produce all kinds of chemicals including life science molecules. In order to develop such catalyst systems, combining both homogeneous and heterogeneous catalysis concepts is considered to be a promising strategy. Applying this approach, special kinds of catalysts such as nanoparticles and single atoms as well as supported homogeneous complexes can be designed. These types of catalysts can overcome the limitations of both molecularly defined complexes and traditional heterogeneous materials. In this respect, in recent years more focus has been paid to the design of these classes of catalysts for organic synthesis. Consequently, in this review, we discuss the application of synergies between homogeneous and heterogeneous catalysis concepts in developing suitable catalysts that exhibit both activity and selectivity as well as stability and reusability. More specifically, selected examples and key achievements made on the preparation and applications of nanoparticles, single atoms, and supported homogeneous complexes for organic transformations are summarized and discussed.