Shadi Moammer - Department of Chemical Engineering, Tehran North Branch, Islamic Azad University, Tehran, Iran
Jafar Towfighi - Department of Chemical Engineering, Tarbiat Modares University, P.O. Box ۱۴۱۱۵-۱۴۳, Tehran, Iran

Thermal cracking of hydrocarbons at ۸۵۰-۹۰۰ degree centigrade is the governing technology worldwide for light olefins production. But the most disadvantages of this route is large energy consumption and air pollution because of flue gas emission containing CO۲ and NOx. To overcome   these drawbacks catalytic cracking is an important and new field for research. So, in this work the effects of temperature and loadings of cerium and lanthanum over HZSM-۵ catalyst for thermal catalytic cracking of naphtha were investigated using response surface methodology. In these experiments, the temperature, Ce, and La loadings were varied from ۶۰۰ to ۷۰۰ °C, ۴ to ۱۲wt.%, and ۰.۸ to ۳wt%, respectively. The Box-Behnken design was utilized and a set of experiments were designed to obtain the optimum catalyst for maximizing the yield of ethylene and propylene. The analysis of variance (ANOVA) was carried out to identify the statistical significance of independent factors and their interactions. The results showed that temperature and Ce loading had the highest effects on the yields of ethylene and propylene, respectively. Based on the multi-objective optimization, the maximum yields of ethylene and propylene (۱۷ and ۳۳wt%, respectively) were obtained at cerium loading of ۱۲ wt.%, lanthanum loading of ۱.۲ wt.%, and temperature of ۷۰۰ °C

Catalytic cracking, light olefins, Optimization, analysis of variance