Selective Oxidative Dehydrogenation of Alkanes over Boron-Containing Catalysts

W.P. McDermott, J.M. Venegas, J.T. Grant, I. Hermans
University of Wisconsin-Madison,
United States

Keywords: natural gas, oxidation, catalysis, hydrocarbons, cracking

Summary:

Ethylene and propylene are typically produced through the steam cracking of naphtha. In recent years, ethane derived from shale gas has become a popular feedstock for steam crackers but the product distribution contains sparing amounts of propylene. On-purpose techniques like propane dehydrogenation (PDH) have been established to meet market demand, but is energy intensive and suffers from significant drawbacks such as catalyst deactivation. An alternative to PDH is oxidative dehydrogenation (ODH) of propane which is more energy efficient and catalysts do not deactivate as readily. However, high selectivity to CO and CO2 prevent industrial implementation. Our group has discovered that hexagonal boron nitride (hBN) and other boron-containing catalysts are active and selective for the ODH of alkanes to their respective olefins. A common active site is likely to be present on on hBN and inorganic borides as they exhibit the same selectivity trends. The surface of used boron-containing catalysts contains oxidized boron as evidenced by x-ray photoelectron spectroscopy (XPS) and other techniques. hBN has also emerged to be a selective catalyst for the oxidation of alkanes to light olefins. Selectivity is controlled through the modulation of O2 concentration which likely stems from a reaction mechanism involving radical species.