Influence of MgO/CeO2 ratio on CO2-oxidative transformation of C2H6 to C2H4 over highly active and stable Cr/MgO(x)-CeO2(100-x) nanocatalysts

摘要

Cr/MgO(x)-CeO2(100-x) nanocatalysts were synthesized by a coprecipitation method and characterized by X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM), energy-dispersive x-ray (EDX) spectroscopy, diffuse reflectance spectroscopy (DRS), and Brunauer-Emmett-Teller (BET) analysis. The effect of ceria addition on their physicochemical characteristics was investigated, and the results were correlated with their catalytic performance in oxidative dehydrogenation of ethane. A decrease in the size of the metal particles was found when adding a suitable content of ceria to the support. Crystalline Cr2O3 was not found in the calcined samples, indicating good dispersion of Cr species on the support. All samples showed nanosized particles with uniform morphology, with the best surface morphology for the Cr/MgO(50)-CeO2(50) sample, on which the particle distribution mainly lay in the range of 40-60 nm. Variation of the amount of Ce in the support led to an enhancement of the Cr6+/Cr3+ ratio, with the highest value for the Cr/MgO(50)-CeO2(50) sample. This catalyst effectively dehydrogenated ethane to ethylene with CO2 at 700 degrees C even after 5 h on-stream, giving 42.76% ethylene yield.