(569f) Oxidative Dehydrogenation of Propane over Boron-Zeolites with Tailored Active Site Speciation

Oxygen-assisted oxidative dehydrogenation of propane (ODHP) as a promising technology to produce propylene from shale gas to help bridge the gap between global demands in a continuously growing market. One of the main challenges of using traditional metal oxide catalysts for this reaction is the overoxidation of propane to COx. Prior studies have demonstrated that boron nitride (h-BN) can achieve approximately 90% light olefins selectivity at 14% propane conversion, thus highlighting the potential of boron-based catalysts in ODHP reactions. To further improve olefins selectivity at higher conversion, other boron containing catalysts have been proposed. The shape-selectivity of zeolites creates opportunities for developing new classes of ODHP catalysts where replacement of aluminum with heteroatoms (e.g., boron) can be a strategy for tuning acid sites for enhanced catalyst performance.

In this presentation, we will highlight our recent studies on several boron-containing zeolites as potential ODHP catalysts. Our findings reveal that B-zeolites can achieve around 80% light olefins selectivity at 40% propane conversion; however, the nature of the active sites, including the impact of boron speciation, has been an elusive subject. We have examined heteroatom incorporation in several different zeolite crystal structures and identified synthesis methods to alter the population of boron framework species, which have been confirmed using techniques such as ¹¹B solid-state NMR spectroscopy. Here we will discuss how catalyst activity and selectivity vary as a function of boron speciation and the impact of distinct pore networks on ODHP reaction performance. These findings offer new insights into the design of heteroatom-substituted zeolite catalysts as alternatives to conventional aluminosilicate analogues.