Fluid Catalytic Cracking Study of Coker Gas Oil: Effects of Processing Parameters on Sulfur and Nitrogen Distributions

Abstract

To investigate the effects of operating conditions and the catalyst activity on the transfer regularity of sulfur and nitrogen during the cracking process of coker gas oil (CGO), the CGO was catalytically cracked in a pilot-scale riser fluid catalytic cracking (FCC) apparatus at different test environments. Then the cracked liquid products were analyzed for sulfur and nitrogen distributions with boiling point, from which the sulfur and nitrogen concentrations of gasoline, light cycle oil (LCO), and heavy cycle oil (HCO) fractions were determined. The sulfur and nitrogen compounds in each product cut, and their possible reaction pathways were reviewed and discussed. The results show that sulfur-containing species are easier to crack but more difficult to be removed from the liquid product, while nitrogen compounds are easier to form coke, then be removed from the liquid product. The sulfur distribution of CGO is different from that of conventional feedstocks. Different processing parameters can significantly affect the sulfur and nitrogen distribution yields and concentrations in liquid products. Increasing the reaction temperature and the catalyst-to-oil ratio as well as shortening the residence time cannot only increase the light oil yield but also improve the product quality and reduce the SO_<i>x</i> and NO_<i>x</i> emissions in the regenerator