The effect of water and zinc loading on LPG catalytic cracking for light olefin production using Response Surface Methodology

Abstract

Optimization of liquefied petroleum gas (LPG) catalytic cracking is one of the most fundamental issues in light olefin production. The Response Surface Methodology (RSM) 5-level-3-factor central composite design (CCD) was used to investigate the effects of zinc loading, water and temperature on ZSM-5 performance. The results show that there is an optimum point for initial propylene and ethylene yields by changing the temperature (from 566 to 634 °C) of zinc metal loading in ZSM-5 (from 0.23 to 1.57 wt%) and the water/LPG ratio (from 0.32 to 2.68), with the yields being 22.34 wt% and 28.20 wt%, respectively. The experimental data were satisfactorily fitted to quadratic models by using multiple regression analysis over the range of operating conditions. The Response Surface Methodology determined the optimal Zn loading set (0.96 wt%), water/LPG ratio (1.86) and temperature (633.6 °C) to obtain the best result for the initial yields of ethylene and propylene. For ethylene and propylene yield responses, in a quadratic model, F-values showed 15.08 and 54.93, respectively, which states that the models were well-fitted.

Keywords

• water
• light olefin yield
• modified zsm-5
• catalytic cracking
• response surface methodology (rsm).