Title

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

Publication Date

2-5-2020

Department

Ames Laboratory; Chemistry

Campus Units

Ames Laboratory, Chemistry

OSTI ID+

1602080

Report Number

IS-J 10172

DOI

10.1002/anie.201914696

Journal Title

Angewandte Chemie International Edition

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)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.

DOE Contract Number(s)

SC0017918; AC02-07CH11358

Language

en

Publisher

Iowa State University Digital Repository, Ames IA (United States)

Share

COinS