CrMn-based catalysts for oxidative dehydrogenation of propane to propylene with CO2

Abstract

The paper investigates the catalytic oxidative dehydrogenation of propane with carbon dioxide (ODH-CO₂) as a promising route for propylene production, an avenue yet to be commercially developed. Utilizing the incipient wetness catalyst preparation method, CrMn catalysts were synthesized on three supports (γ-Al₂O₃, ZSM-5, and SBA-15). Comprehensive characterization through Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM)/scanning transmission electron microscopy (STEM)-energy-dispersive X-ray spectroscopy (EDS), and hydrogen temperature programmed reduction (H₂-TPR) was conducted to comprehend catalyst behaviour. Among the six catalysts tested, Cr/SBA-15 was exhibited as the best performer, achieving propane and CO₂ conversions of 36.2% and 14.1%, respectively, with a propylene selectivity of 33.4%. Over a 50-h time on stream (TOS), it demonstrated gradual declines in conversions while retaining 75% of initial values. The incorporation of manganese as a promoter effectively mitigated coke formation, albeit with slight reductions in propane conversion and propylene selectivity.