The effect of key factors on thermal catalytic cracking of naphtha over Ce–La/SAPO-34 catalyst by statistical design of experiments

Cerium and lanthanum catalysts supported on SAPO-34 were synthesized and used in thermal catalytic cracking of naphtha to produce light olefins. Synthesized catalysts were characterized by SEM and XRD techniques. The effect of Ce loading (4–12 wt%), La loading(0.8–3 wt%) and temperature (650–750 °C) on ethylene and propylene yield were studied by Box–Behnken experimental design.The significance of independent factors and their quadratic interactions were examined by means of the Analysis of Variance (ANOVA). The results showed that the most significant factor in yield of ethylene and propylene production was temperature. The optimum values of the variables were obtained by the quadratic model and the response surface contour plots. Results indicated that the catalyst whit low level of lanthanum loading, high level of cerium loading and temperature of 750 °C produced maximum yield of ethylene (26.7 wt%) while maximum yield of propylene (22.54 wt%) was obtained for 1.5 wt% of lanthanum loading and 8 wt% of cerium loading and temperature of 740 °C that reached to 22.54 wt%.

► SAPO-34 decorated with Ce oxide and La oxide was used in the thermal catalytic cracking process. ► A new model generated to estimate the yield of ethylene and propylene. ► Optimizing of Ce loading, La loading and temperature. ► Investigation the parameters interactions.