A Perspective on Catalysis in Solid Acids

Abstract

Solid acids are among the most important heterogeneous catalysts, finding many applications ranging from hydrocarbon cracking and alkane isomerization [1] in petroleum refining to valorization of biomass [2]. Even though the subject is quite old, new materials and applications are still being developed. Some of the new applications involve solid Lewis acids, such as metal-substituted, siliceous zeolites (e.g. Sn-BEA [3-5]); but new Brønsted acids [6] and applications for Brønsted acids [7-9] are appearing as well. Although there have been many excellent reviews of solid acidity and methods for characterizing solid acids [10-12], there is still much that we do not know about the nature of acid sites in solids and the factors which are most important for influencing catalytic activity. In this perspective, we will discuss some concepts that we feel are important for understanding these materials and the reactions they catalyze. Because our understanding of Lewis acids is much less advanced, we will restrict our comments to solids with Brønsted acidity and refer the reader to other recent publications on Lewis acids [13-15].