Electrospinning synthesis of porous boron-doped silica nanofibers for oxidative dehydrogenation of light alkanes

Abstract

The discovery of the high activity and selectivity of boron-based catalysts for oxidative dehydrogenation (ODH) of alkanes to olefins has attracted significant attention in the exploration of a new method for the synthesis of highly active and selective catalysts. Herein, we describe the synthesis of porous boron-doped silica nanofibers (PBSNs) 100–150 nm in diameter by electrospinning and the study of their catalytic performance. The electrospinning synthesis of the catalyst ensures the uniform dispersion and stability of the boron species on the open silica fiber framework. The one-dimensional nanofibers with open pore structures not only prevented diffusion limitation but also guaranteed high catalytic activity at high weight hourly space velocity (WHSV) in the ODH of alkanes. Compared to other supported boron oxide catalysts, PBSN catalysts showed higher olefin selectivity and stability. The presence of Si−OH groups in silica-supported boron catalysts may cause low propylene selectivity during the ODH of propane. When the ODH conversion of ethane reached 44.3%, the selectivity and productivity of ethylene were 84% and 44.2% gcat−1 s−1, respectively. In the case of propane ODH, the conversion, selectivity of olefins, and productivity of propylene are 19.2%, 90%, and 76.6 μmol gcat−1 s−1, respectively. No significant variations in the conversion and product selectivity occurred during 20 h of operation at a high WHSV of 84.6 h−1. Transient analysis and kinetic experiments indicated that the activation of O2 was influenced by alkanes during the ODH reaction.