Mechanistic aspects of ethylbenzene dehydrogenation with CO2 over K2O/B2O3 -TiO2 - ZrO2 bi-funotional catalysts

摘要

TiO2-ZrO2 bi-functional catalysts were prepared by co-precipitation method using aqueous NHj solution as a hydrolyzing agent. Either K2O promoter or B2 O3 promoter has been deposited 60% TiOi -ZrO2 by wet-impregnation techniques. The catalytic activity of both K2O promoted and BT OJ promoted TiO2 -ZrO2 acid base bi-functional catalysts has been studied for the oxidative dehydrogenation of ethylbenzene in the presence of CO2. The higher conversion of ethylbenzene and higher selectivity of styrene has been obtained on the K2O promoted TiOi-ZrO2 catalysts. On the other hand, B2O3 promoted TiCK -ZrO2 catalysts exhibited lower catalytic activity than those of K2O promoted T1O2 -ZrO2 catalysts, In the mechanistic point of view both K2O promoted TiOj -ZrO2 catalysts and B2O3 promoted TiOi-ZrO2 catalysts following the different pathways. This synergistic promotional effects of K2O and CO2 enhanced the selectivity of styrene (98 - 99%) by sustaining the higher conversions of ethylbenzene (60 -65%).