Natural polymers, silica, and carbon-based aerogels: catalytic applications in fine chemical synthesis. An overview

Aerogels are extremely versatile materials with a great variety of potential applications, mainly including energy storage and conversion, thermal energy and sound insulation, biomedicine, and environmental applications. They can be prepared from almost any material presenting a notably low density, large specific surface areas, different pore sizes in the range of meso and macroporosity, and tuneable surface chemistry; all these characteristics making them interesting materials for catalytic applications. This chapter summarizes the most useful synthetic strategies for the preparation of some types of aerogels such as aerogels from natural polymers, or silica and carbon aerogels and its catalytic applications, particularly in the synthesis of highly valuable compounds, an issue explored in a lesser extent. In this context, special attention has deserved the aerogel-supported nanoparticles. Remarkably, aerogels from natural polymers can be considered very promising materials because it combines the use of sustainable materials, the existence of multiple functional groups at the surface and the possibility to obtain an adjustable morphology. However, these materials show considerable inferior thermal and mechanical stability when compared to silica- and carbon-derived aerogels. Therefore, much more efforts are still needed to improve the catalytic applicability of natural polymers-based aerogels to overcome some inconveniences.