Lewis Acidity in Cracking and Polymerization Catalysis


Ph.D. defense of Marjolein Velthoen

Cracking and polymerization processes are important industrial processes. In cracking, crude oil fractions are cracked into useful products, such as gasoline, LPG, and small molecules such as propylene and ethylene. In the polymerization process, these small molecules (monomers) are connected to form one large molecule (polymer).  In both chemical processes, a catalyst is used to let these reactions proceed in a faster, more effective way. Interestingly, the active sites of the catalysts that are used in these two different processes rely on the same chemical nature: Lewis acidity. 

A Lewis acid site has an electron deficiency. Molecules with an abundance of electrons are drawn towards this Lewis acid site. This Ph.D. thesis describes the nature of Lewis acid sites in the catalysts that are active in the cracking and polymerization reaction. To that end, multiple characterization techniques have been used, combined, and further developed. A new characterization technique that provides additional information on the nature of Lewis acid sites has been developed as well. By gathering information on what comprises a Lewis acid site, more understanding is gained on how catalysts operate in these two chemical processes and, in particular, the role of Lewis acid sites.

Source: website Utrecht University