(23a) Hierarchical Zeolites: Synthetic Strategies, Mesopore Configuration, and Applications in Aromatics Conversion

There has been growing interest in the research and development of hierarchical zeolites possessing at least two levels of porosity in order to reduce diffusion limitations in reactions catalyzed by microporous zeolites. Hierarchical zeolites can be synthesized by different strategies, resulting in the creation of mesoporosity with different configurations (i.e. inter-crystalline or intra-crystalline) in addition to some unique pore properties that are oftentimes characteristic to specific synthetic routes, such as top-down or bottom-up syntheses. The top-down strategy uses microporous zeolites for post-synthetic modifications to create hierarchical structures, while the bottom-up strategy usually creates hierarchical structures through the engineering of microporous and mesoporous domains by various template materials. In this talk, the distinctive features of hierarchical zeolites synthesized by different approaches will be discussed together with the scale-up feasibility associated with these strategies. In-depth analysis will be dedicated to elaborating the effect of mesopore configuration on catalytic activity and to identifying the merits of mesoporosity in improving catalytic performances of hierarchical zeolites. Meanwhile, we will demonstrate the unique advantages of using hierarchical (beta) zeolites in the catalytic selective ring-opening of aromatics to value-added mono-aromatic chemicals.