K10 montmorillonite clays as environmentally benign catalysts for organic reactions

Montmorillonite is one of the most intensively explored catalytic materials in heterogeneous catalysis due to its low cost and eco-friendliness. Also, it possesses some unique properties like cation exchange capacity and swelling ability, thereby accommodating various guest species in its interlayers. In this Perspective, we describe the catalytic utility of K10-montmorillonite as solid acids and supports for complexes or metal nanoparticles in unimolecular as well as bimolecular reactions as reported mainly by our group. A very brief introduction is presented to highlight the structural properties of K10 clay and its merits in heterogeneous catalysis. The main part of this review is organized according to the role of clay in various organic reactions. An emphasis is given to highlighting the greenness of the processes, and a fair comparison is also provided between clay catalysts with respect to other homogeneous or heterogeneous catalysts. Finally, we summarize the current status and provide our views on future trends and developments.