Morphological effects of ordered Cr2O3 nanorods and Cr2O3 nanoparticles on fluorination of 2-chloro-1,1,1-trifluoroethane

摘要

Ordered Cr2O3 nanorods (Cr2O3-R) and Cr2O3 nanoparticles (Cr2O3-P) were prepared by a hard template method with SBA-15 and a deposition-precipitation method, respectively. These catalysts were tested for the fluorination of 2-chloro-1,1,1-trifluoroethane (HCFC-133a) to synthesize 1,1,1,2-tetrafluoroethane (HFC-134a). It was found that both catalysts were very selective, with a HFC-134a selectivity of 98 %. However, the Cr2O3-R catalyst had an area specific reaction rate of 0.012 mu mol m(-2) s(-1) at 320 A degrees C, which was much higher than that on the Cr2O3-P (0.005 mu mol m(-2) s(-1)). The enhanced activity of the Cr2O3-R was attributed to its higher content of Cr(VI) species compared to that in the Cr2O3-P, which was evidenced by the hydrogen temperature-programmed reduction and X-ray photoelectron spectroscopy results. Besides, the Cr2O3-R catalyst had a higher surface acid density (0.076 mmol m(-2)) than the Cr2O3-P (0.068 mmol m(-2)), which could be another reason for its better performance.