During the traditional downstream refinement process, zeolitic materials are often used as catalysts due to their excellent hydrothermal stability and high acidity in order to crack the hydrocarbons from crude oil into lower boiling point small molecules. Conventionally used zeolites are limited by their small micropore sizes (&lt;20 Å) and are unable to accommodate the larger substrates of crude oil, resulting in a vacuum residue that is often times flared off or burned for electricity. The past decade has seen the development of hierarchical zeolites with at least one additional porosity, which is usually in the mesopore range, as a way to overcome the diffusion limitations presented by conventional zeolites.<br/><br/>In this work, we discuss the generation of mesopores in Beta zeolites of differing starting aluminum contents (Si/Al= 14-250) through a top-down base leaching treatment with different pore-directing agents (PDAs). The use of PDAs has previously been shown to prevent amorphization of zeolite crystals from excessive desilication during NaOH treatment, leading to hierarchical zeolite materials with well-preserved microporosity. Over eleven molecules of different type and structures (amines, tetraalkylammonium cations, etc.) were tested as PDAs with the results suggesting that the molecule size and charge/affinity can positively influence the textural properties of the zeolites. Our work shows that selecting the appropriate pore-directing agent can allow for tailoring of the mesopore size and volume for desired catalytic applications. Choosing a larger tetraalkyammonium cation, for example, can lead to smaller mesopores compared to smaller cations. The hierarchical zeolites generated are studied and characterized by traditional techniques, such as Ar Physisorption, TEM, SEM, XRD, NH<sub>3</sub>-TPD, etc. The performance of these materials in industrially-relevant acid-catalyzed reactions will be discussed.

Tailored hierarchical pore structures of beta zeolites through PDA-assisted base leaching

255th National Meeting (2018)

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