Oxidative dehydrogenation of ethane over alkali metal chloride modified silica catalysts

The catalytic oxidative dehydrogenation of ethane into ethylene was investi gated over a series of alkali metal chloride supported on silica catalysts. It is found that alkali metal chloride modified silica catalysts show much higher activity in the selective oxidation of ethane than silica support i tself, and their catalytic activity depends on the nature of alkali metal a nd its loading. LiCl/ SiO2 exhibits the highest ethane conversion and ethyl ene yield, giving 99% ethane conversion and 80% ethylene selectivity at 600 degrees C. However, it shows rapid deactivation. NaCl/SiO2 shows high conv ersion and a longer stability. On the contrary, KCl/SiO2 displays the lowes t ethane conversion but a high deactivation rate. Characterization of the c atalysts reveals that the activity variation can be related to the redox an d acid-base properties of the catalysts. The deactivation of catalytic acti vity can be attributed to the loss of chlorine and chemical phase transform ation.