Improved Catalytic Performance of Direct Dehydrogenation of Ethylbenzene by Creating Boron Defects on Phosphorus-doped Boron Nitride

Abstract

Phosphorus-doped boron nitride (PBN) has been confirmed as an effective metal-free catalyst for the direct dehydrogenation (DDH) of ethylbenzene to styrene. In this paper, we further used barbituric acid as co-reactant sources to create B defects in both PBN and mesoporous PBN (m-PBN) materials. The XPS, N2 adsorption-desorption, UV-vis DRS, EPR, 11B SS NMR characterizations indicated both the electronic and pore structures of the catalyst with B defects were adjusted. Except for the improvement of mass transfer caused by B defects, DFT calculations showed the increase of electron density in B defects areas could enhance the breaking of C−H in ethylbenzene and the bond-forming of H−H, which was acted to improve the catalytic activity. The m-PBN with B defects delivered the styrene production rate of 22.54 mmolST g−1 h−1 and stably run 300 h when in-situ grown on Al2O3, proving that defect tuning strategy is useful to construct efficient catalysts for styrene production.