One-dimensional Ga2O3-Al2O3 nanofibers with unsaturated coordination Ga: Catalytic dehydrogenation of propane under CO2 atmosphere with excellent stability

Abstract

The pressing demand for propylene has spurred intensive research on the catalytic dehydrogenation of propane to produce propylene. Gallium-based catalysts are regarded as highly promising due to their exceptional dehydrogenation activity in the presence of CO2. However, the inherent coking issue associated with high temperature reactions poses a constraint on the stability development of this process. In this study, we employed the electrospinning method to prepare a range of Ga2O3-Al2O3 mixed oxide one-dimensional nanofiber catalysts with varying molar ratios for CO2 oxidative dehydrogenation of propane (CO2-OPDH). The propane conversion was up to 48.4 % and the propylene selectivity was high as 96.8 % at 500 °C, the ratio of propane to carbon dioxide is 1:2. After 100 h of reaction, the catalyst still maintains approximately 10 % conversion and exhibits a propylene selectivity of around 98 %. The electrospinning method produces one-dimensional nanostructures with a larger specific surface area, unique multi-stage pore structure and low-coordinated Ga3+, which enhances mass transfer and accelerates reaction intermediates. This results in less coking and improved catalyst stability. The high activity of the catalyst is attributed to an abundance of low-coordinated Ga3+ ions associated with weak/medium-strong Lewis acid centers. In situ infrared analysis reveals that the reaction mechanism involves a two-step dehydrogenation via propane isocleavage, with the second dehydrogenation of Ga-OR at the metal–oxygen bond being the decisive speed step.