| The recent surge in shale gas resources creates new opportunities to improve process efficiencies for the production of important chemical building blocks. Non-oxidative dehydrogenation of propane (PDH), the primary "on-purpose" propylene technology used worldwide today, has process inefficiencies that may be improved by co-feeding oxygen and propane to drive the oxidative dehydrogenation (ODH) of propane reaction. However, after decades of catalyst research for ODH of propane this reaction has yet to be commercialized due to the difficulty of controlling this partial oxidation to selectively yield propylene rather than the more-thermodynamically stable CO and CO2 (COx) products.;This thesis explores the reactivity and properties of two very different classes of catalysts for the ODH of alkanes: 1) supported vanadia and 2) boron-containing catalysts. Supported vanadia catalysts, the most-studied catalyst for this transformation in the literature, show markedly higher selectivity to propylene when existing as dispersed two-dimensional metal oxide surface species. By introducing a small amount of Na+ to the surface of SiO 2, the maximum two-dimensional surface density can be dramatically enhanced. This effect is proved using spectroscopic characterization, as well as the ODH of propane used as a probe reaction.;Boron-containing compounds, especially boron nitride (BN) materials, were previously overlooked as catalysts for the ODH of alkanes, and rather deemed to be inert. On the contrary, these B-containing catalysts are now considered to be among the most-selective catalysts for the ODH of alkanes as a method to form their corresponding olefins. The rate of alkane consumption is dependent on oxygen adsorption to the catalyst surface, and shows second-order dependence in the concentration of the alkane. At these temperatures (400--500 °C) oxygen adsorption to the B-containing catalyst only occurs when exposed to the ODH reaction (not only air or a combination of air and steam), and is verified with numerous spectroscopic techniques including X-ray Photoelectron Spectroscopy (XPS), and Attenuated Total Reflectance Infrared (ATR-IR). Recent work with X-ray Absorption Spectroscopy (XAS) and 11B MAS NMR dismisses the possibility that a potential B2O3 surface layer acts as the active site by revealing that B2O 3 is not present on spent catalysts. |
