B-MWW Zeolite: The Case Against Single-Site Catalysis

Natalie R. Altvater, Rick W. Dorn, Melissa C. Cendejas, William P. McDermott, Brijith Thomas, Aaron J. Rossini, Ive Hermans

Research output: Contribution to journalArticlepeer-review

Abstract

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)xO(3x/2) (x = 0–6) 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 (BMWW). 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 vanadiumbased catalysts and provides an important piece of the mechanistic puzzle.

Original languageEnglish (US)
Pages (from-to)6608-6612
Number of pages5
JournalAdvanced Materials
Volume132
Issue number16
DOIs
StatePublished - 2020

Keywords

  • boron
  • heterogeneous catalysis
  • oxidative dehydrogenation
  • solid-state NMR
  • zeolites

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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