Review: cascade reactions for conversion of carbohydrates using heteropolyacids as the solid catalysts

Conversion of biomass into renewable chemicals and fuels has received significant attention as an approach to enhance global sustainability. Biomass conversion, especially carbohydrate conversion, commonly involves cascade reactions. During these cascade reactions, various activity sites on carbohydrates may have different reactivities that enable us to control the final products through adjusting these activity sites. Heteropolyacids (HPAs), one of the major solid acid catalysts, are extensively used in biomass conversion owing to their numerous excellent physicochemical properties, such as strong Bronsted acidity, oxidizability, structural versatility, and easy design. Accordingly, this review aims to outline recent breakthroughs in obtaining platform chemicals from carbohydrates by cascade reactions involving heteropolyacid catalysts. Moreover, the relationship between the final products and the structure of heteropolyacid catalysts is discussed and insights will help us to design more efficient solid acid catalysts for conversion of biomass to more sustainable chemical products.