Zeolites in catalysis: sustainable synthesis and its impact on properties and applications

Zeolites are versatile catalysts not only for large scale petrochemical processes but also in applications related to fine chemicals synthesis, biomass conversion and CO2 utilization. Introduction of mesopores and heteroatoms opens up additional applications. Heteroatoms in the crystalline framework create active sites where the diversity in the coordination offers tunability in acidity and redox properties. Their framework locations within the unit cell and their open/closed nature greatly influence the catalytic ability. Depending on the synthesis conditions, the properties of the pore walls can vary from hydrophobic to hydrophilic which affects the confinement of reactant and solvent molecules within the well-ordered pores. This mini-review traces the synthesis of heteroatom zeolites from traditional solvent-based methods to the more sustainable routes of post-synthesis and mechanochemistry. The properties of the zeolites formed by the different methods are compared and the impact on selected catalytic reactions is discussed.