Oxidative dehydrogenation of ethane to ethylene over LiCl/SO42--ZrO2 catalyst

摘要

Sulfated zirconia (SO42--ZrO2) samples were prepared by a modified two-step method (refluxing ZrO(OH)(2) precursor in basic solution followed by drying and (NH4)(2)SO4 impregnation) and then impregnated with a LiCl solution to give the SO42--ZrO2-supported LICI catalysts with Li mass content of 0.5% similar to 15%. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, N-2 adsorption, temperature-programmed desorption-mass spectrometry, and X-ray photoelectron spectroscopy. The results show that with increasing LiCl loading, the specific surface area and acidity of the catalysts as well as the volume fraction of tetragonal zirconia in the catalysts decrease, while the catalytic performance of the catalysts for oxidative dehydrogenation of ethane (ODHE) to ethylene increases. Over the LiCl/SO42--ZrO2 catalyst with a Li content of 15% ethylene yield of 77.8% with an ethane conversion of 90.6% is achieved at 650 degrees C, and the yield higher than 71% is maintained over a period of 24 h. The textural structure of ZrO? has little effect on the catalytic behavior of the LiCl/SO42--ZrO2 catalysts. The specific surface area of SO42--ZrO2 samples prepared by the fled two-step method is much bigger than that of the SO42--ZrO2 samples made by the method reported in literature, and therefore more LiCl call be loaded on unit mass of support. This is favorable to improve the catalyst stability and slow down catalyst deactivation during the ODHE reaction due to the loss of LiCl.