Enhanced performance of boron nitride catalysts with induction period for the oxidative dehydrogenation of ethane to ethylene

Hexagonal boron nitride (h-BN) has recently aroused continuous interest in the oxidative dehydrogenation (ODH) of light alkanes. Here we found that commercial h-BN exhibits an induction period during the ODH of ethane to ethylene. It can achieve better performance only on activated BN after the first cycle run of ODH or treatment of reactants together. The conversion of ethane was 36% at a selectivity of 79% on the activated BN at 570 degrees C, which nearly tripled that on the fresh BN (12% conversion with 84% selectivity). An excellent productivity of 110 mu mol g(cat)(-1) s(-1) was obtained, which was one order of magnitude higher than that on most previous catalysts. Various methods of characterization such as infrared spectroscopy, O-2 adsorption microcalorimetry, and transient analysis of products by mass spectroscopy indicated the formation of B-OH species on BN after the induction period. There was a linear relationship between the reaction rate of ethane and the quantity of OH species. It is suggested that B-OH species can facilitate the adsorption of O-2 and then be transformed to B-O species, which would react with ethane to produce ethylene with the assistance of O-2, thus resulting in a higher reaction rate and a lower activation energy. (C) 2018 Elsevier Inc. All rights reserved.