Radical Chemistry and Reaction Mechanisms of Propane Oxidative Dehydrogenation over Hexagonal Boron Nitride Catalysts

Xuanyu Zhang; Rui You; Zeyue Wei; Xiao Jiang; Jiuzhong Yang; Yang Pan; Peiwen Wu; Qingdong Jia; Zhenghong Bao; Lei Bai; Mingzhou Jin; Bobby Sumpter; Victor Fung; Weixin Huang; Zili Wu

doi:10.1002/anie.202002440

Radical Chemistry and Reaction Mechanisms of Propane Oxidative Dehydrogenation over Hexagonal Boron Nitride Catalysts

Angew Chem Int Ed Engl. 2020 May 18;59(21):8042-8046. doi: 10.1002/anie.202002440. Epub 2020 Apr 15.

Authors

Xuanyu Zhang^{1

2}, Rui You¹, Zeyue Wei¹, Xiao Jiang², Jiuzhong Yang³, Yang Pan³, Peiwen Wu⁴, Qingdong Jia⁴, Zhenghong Bao², Lei Bai², Mingzhou Jin⁵, Bobby Sumpter⁶, Victor Fung⁶, Weixin Huang¹, Zili Wu²

Affiliations

¹ Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, CAS key Laboratory of Materials for Energy Conversion and Department of Chemical Physics, University of Science and Technology of China, Heifei, 230026, P. R. China.
² Chemical Sciences Division and Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
³ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Heifei, 230026, P. R. China.
⁴ School of Chemistry and Chemical Engineering, Jiang Su University, Zhenjiang, 212013, P. R. China.
⁵ Institute of a Secure and Sustainable Environment, The University of Tennessee, Knoxville, Knoxville, TN, 37996, USA.
⁶ Center for Nanophase Materials Science and Computational Sciences & Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.

PMID: 32203632
DOI: 10.1002/anie.202002440

Abstract

Although hexagonal boron nitride (h-BN) has recently been identified as a highly efficient catalyst for the oxidative dehydrogenation of propane (ODHP) reaction, the reaction mechanisms, especially regarding radical chemistry of this system, remain elusive. Now, the first direct experimental evidence of gas-phase methyl radicals (CH₃ ^. ) in the ODHP reaction over boron-based catalysts is achieved by using online synchrotron vacuum ultraviolet photoionization mass spectroscopy (SVUV-PIMS), which uncovers the existence of gas-phase radical pathways. Combined with density functional theory (DFT) calculations, the results demonstrate that propene is mainly generated on the catalyst surface from the C-H activation of propane, while C₂ and C₁ products can be formed via both surface-mediated and gas-phase pathways. These observations provide new insights towards understanding the ODHP reaction mechanisms over boron-based catalysts.

Keywords: hexagonal boron nitride; mass spectrometry; methyl radicals; oxidative dehydrogenation; reaction pathways.

Abstract

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