Fibrous Silica-Supported Ni–Bi Oxide Catalysts for Oxidative Dehydrogenation of n-Butane

Abstract

Ni–Bi oxides supported on novel fibrous silica nanospheres were evaluated as catalysts for the oxidative dehydrogenation (ODH) of n-butane to 1,3-butadiene (BD) in a continuous-flow fixed-bed reactor under varying reaction conditions, including the temperature and oxygen-to-n-butane ratios. The fibrous silica nanospheres were synthesized using a straightforward hydrothermal template-assisted method, followed by the impregnation of Ni (10–20 wt %) and Bi (10–30 wt %) onto the silica support. Characterization confirmed the presence of NiO and Bi₂SiO₅ phases in the Ni–Bi–O_x/FS catalyst system. An optimized combination of acidic and basic sites was found to enhance the catalytic activity and selectivity. Notably, the 20Ni–10Bi/FS catalyst demonstrated 40.1% n-butane conversion and 20% butadiene yield, with a dehydrogenation selectivity of 71.6% (50.0% BD and 21.6% butenes) at 500 °C and an oxygen-to-butane ratio of 1. The catalyst maintained stable catalytic performance and selectivity over 32 h of continuous operation. Thermogravimetric analysis (TGA) of the spent catalyst confirmed its high stability. This study provides further insights into the development of high-performance ODH catalysts.