Identification of active sites in boron nitride for propane oxidative dehydrogenation catalysis

Abstract

The oxidative dehydrogenation of propane (ODHP) represents a highly promising route for the industrial-scale production of propene. Non-metallic boron nitride (BN)-based materials, known for their high propene selectivity, have emerged as next-generation ODH catalysts. However, the real active sites on surfaces remain unclear due to the absence of visual experimental evidence. In this work, we introduce a chemical titration approach to clarify the active centers of NaOH modified BN (BN-NaOH) catalysts for ODHP. The BN-NaOH catalyst demonstrates outstanding performance, achieving over 90 % olefin selectivity and a stable propane conversion of 23.2 %. Notably, the turnover frequency (TOF) for B-OH sites reaching 1.2 h⁻¹, which significantly surpassed that of unmodified BN catalysts (0.6 h⁻¹). In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis revealed that the formation of OH-nests on the BN-NaOH surface was primarily accountable for the enhanced reactivity. Moreover, the crucial role of these OH-nests during ODHP was further validated through selective chemical titration of B-OH groups using benzoic anhydride.