Engineering O-O Species in Boron Nitrous Nanotubes Increases Olefins for Propane Oxidative Dehydrogenation.

ABSTRACT

Boron nitride (BN) has been widely studied as an efficient catalyst for oxidative propane dehydrogenation (OPDH). Oxygen-containing boron species (e.g., BO·, B(OH)xO3-x) are generally considered as the active centers in BN for OPDH. Here, we show an effective progressive substitution strategy toward the development of boron-oxygen-nitrogen nanotubes (BONNTs) enriched with O-O species as a highly active, selective, and stable catalyst for OPDH. At 525 °C, an olefin yield of 48.6% is achieved over BONNTs with a propane conversion of 64.4%, 2.8 times that of boron nitrogen nanotubes (BNNTs). Even after reaction for 150 h (475 °C), BONNTs exhibit good olefin yield. Both the B(OH)xO3-x and O-O species that coexist in the BONNT catalyst are demonstrated as active centers, which differs from the B(OH)xO3-x one in BNNTs. Based on catalytic results, propane and oxygen alternate treatment experiments, and theoretical calculations, the O-O center is more favorable for producing both propylene (C3=) and ethylene (C2=), which experiences a dehydration pathway and two possible reaction paths with a lower energy barrier to yield olefins, while B(OH)xO3-x is mainly responsible for producing few C3=.