Electrospun Mo─SiO2 nanofibers as heterogeneous catalysts for propylene metathesis

Abstract

Olefin metathesis catalysts based on molybdenum exhibit superior performance at low temperatures when they contain highly dispersed MoOx species within the catalyst support. However, the preparation methods that achieve this high dispersion are often difficult to scale up. In this study, we report the scalable synthesis of molybdenum silicate (Mo─SiO2) nanofibers (NFs) via electrospinning, aimed at producing catalysts active in olefin metathesis reactions. The resulting NFs had diameters ranging from 70 to 209 nm and exhibited high surface areas, reaching up to 920 m2 g−1. A comprehensive characterization of the MoOx active sites—using powder x-ray diffraction analysis, Raman spectroscopy, x-ray photoelectron spectroscopy, HRTEM, H2-TPR, and in situ DRUV–Vis—confirmed the absence of crystalline phases, indicating a high degree of dispersion and uniformity. Among the prepared samples, Mo─SiO2 containing 5 wt% Mo, with an average fiber diameter of 104 nm and a surface area of 456 m2 g−1, demonstrated exceptional catalytic performance in propylene self-metathesis. It achieved a propylene metathesis rate of 17.1 µmol g−1 s−1 at 200°C, significantly outperforming a catalyst prepared via incipient wetness impregnation, used here as a model for industrial benchmarks.