The effect of ethanol on the performance of CrOx/SiO2 catalysts during propane dehydrogenation

The effects of ethanol vapor pretreatment on the performance of CrOx/SiO2 catalysts during the dehydrogenation of propane to propylene were studied with and without the presence of CO2. The catalyst pretreated with ethanol vapor exhibited better catalytic activity than the pristine CrOx/SiO2, generating 41.4% propane conversion and 84.8% propylene selectivity. The various catalyst samples prepared were characterized by X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, X-ray photoelectron spectroscopy and reflectance UV-Vis spectroscopy. The data show that coordinative Cr3+ species represent the active sites during the dehydrogenation of propane and that these species serve as precursors for the generation of Cr3+. Cr3+ is reduced during the reaction, leading to a decrease in catalytic activity. Following ethanol vapor pretreatment, the reduced CrOx in the catalyst is readily re-oxidized to Cr6+ by CO2. The pretreated catalyst thus exhibits high activity during the propane dehydrogenation reaction by maintaining the active Cr3+ states.

Graphical AbstractThe coordinated Cr6+ was reduced to lower oxidation state of Cr by the ethanol vapor pretreatment, Cr3+ and Cr2+ of CrH-Et was easily regenerated to Cr6+ by CO2 comparing with CrH, indicating that higher concentration of Cr6+ existed on CrH during the dehydrogenation reaction.Figure optionsDownload as PowerPoint slide