Oil refinery residue upgrading using ZSM-5 catalyst: statistical analysis and optimization with response surface methodology

Abstract

In this research, optimization and statistical analysis of upgrading Iranian oil refinery residue in the presence of an H-ZSM-5 catalyst using RSM were performed. The residue (specific gravity: 0.9625, API: 15.5, viscosity (at 50 0C): 275 cSt) was from Abadan oil refinery, Iran. Twenty-nine experiments were designed at five levels of temperature (360 to 440 0C) and five levels of catalyst/feed ratio (30 to 70 wt%). The processing time in all experiments was 2 hr. The responses contained conversion, API, specific gravity, and viscosity. The catalyst was analyzed using XRD, SEM, EDX, and FTIR. RSM was used to model the responses. Quadratic polynomial equations were presented for the models. Based on the results, temperature and catalyst/feed ratio had significant effects on the responses of conversion, API, specific gravity, and viscosity. The interaction of independent variables was just significant for viscosity response. The carbon number variations for the feed and the product were 13 to 50 (230 to 582 °C) and 5 to 16 (47 to 273 °C), respectively. In the optimum conditions, including temperature: 439 °C and cat/feed ratio: 69 wt%, conversion, specific gravity, viscosity, and API of the upgraded residue were 64.09 wt%, 0.8202, 4.50 cSt, and 41.00, respectively.