Biomass Conversion over Zeolite Catalysts
This chapter reviews the main routes for the conversion of biomass into biofuels and bio-based chemicals in which zeolitic catalysts play a major role. Thereby, the different transformations have been organized according firstly to the nature of the raw biomass, with especial emphasis on non-edible oleaginous and lignocellulosic feedstock, and secondly to the type of transformation being applied. Biomass valorization faces several challenges due the complexity of the raw materials, the presence of heteroatoms, and the need in many cases to perform transformations in aqueous liquid media. Zeolites are typically known by exhibiting a set of singular properties that explain their application in a very large number of catalytic processes. Crystallinity, uniform microporosity, well-defined acid sites, shape selectivity, and high thermal stability are essential features in most zeolite-catalysed transformations. However, to fulfil the challenges associated with biomass conversion, new properties of zeolites have been developed in recent years. As discussed in this chapter, this includes the generation of hierarchical porosity having both micro- and mesopores, the modification of the acid properties regarding especially Lewis acidity, the creation of basic sites, control of the hydrophobicity, and the development of multifunctional zeolite catalysts.