B‐MWW Zeolite: The Case Against Single‐Site Catalysis
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Boron‐containing materials have recently been identified as highly selective catalysts for the oxidative dehydrogenation (ODH) of alkanes to olefins. It has previously been demonstrated by several spectroscopic characterization techniques that the surface of these boron‐containing ODH catalysts oxidize and hydrolyze under reaction conditions, forming an amorphous B2(OH)2xO(3 – x) (x = 0 ‐ 3) layer. Yet, the precise nature of the active site(s) remains elusive. In this communication, we provide a detailed characterization of zeolite MCM‐22 isomorphously substituted with boron (B‐MWW). Using 11B solid‐state NMR spectroscopy, we show that the majority of boron species in B‐MWW exist as isolated BO3 units, fully incorporated into the zeolite framework. However, this material shows no catalytic activity for ODH of propane to propene. The catalytic inactivity of B‐MWW for ODH of propane falsifies the hypothesis that site‐isolated BO3 units are the active site in boron‐based catalysts. This observation is at odds with other traditionally studied catalysts like vanadium‐based catalysts and provides an important piece of the mechanistic puzzle.
This is the peer-reviewed version of the following article: Altvater, Natalie, Rick Dorn, melissa Cendejas, William McDermott, Brijith Thomas, Aaron Rossini, and Ive Hermans. "B‐MWW Zeolite: The Case Against Single‐Site Catalysis." Angewandte Chemie (2020), which has been published in final form at DOI: 10.1002/anie.201914696. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Posted with permission.