Study on the Catalytic Pyrolysis of Naphtha over a KVO<INF>3</INF>/α-Al<INF>2</INF>O<INF>3</INF> Catalyst for Production of Light Olefins

The catalytic pyrolysis of naphtha has been carried out with 5 mm KVO<INF>3</INF>-impregnated α-Al<INF>2</INF>O<INF>3</INF>. The yields of ethylene and propylene exhibit about 10% and 5% higher values compared to the thermal pyrolysis in a vacant tube at the same operation condition. This increase in the olefin yield comes from the thermal effect through the better heat transfer. The amount of coke accumulated on the catalyst during the pyrolysis increases with an increase in the reaction temperature and the axial length of the reactor. The role of KVO<INF>3</INF> is to suppress the coke deposition on the catalyst surface. The addition of B<INF>2</INF>O<INF>3</INF> to the KVO<INF>3</INF>/α-Al<INF>2</INF>O<INF>3</INF> system causes a strong interaction between KVO<INF>3</INF> and α-Al<INF>2</INF>O<INF>3</INF>. The results of temperature-programmed reduction and X-ray photoelectron spectroscopy suggest that KVO<INF>3</INF> may be reduced to KVO<INF>1.5</INF> during the pyrolysis reaction. The weight loss of K and V in the catalyst occurs during the pyrolysis.