Christopher F. Dean

Chapter 1 Development of high-severity FCC process: an overview

Abstract High-severity fluid catalytic cracking (HS-FCC) is a new process for the conversion of heavy oils into lighter hydrocarbon products and petrochemical feedstocks. Research teams from Japan and Saudi Arabia are jointly developing this technology. The process combines mechanical modifications to conventional FCC with changes in process variables and catalyst formulations. The main operating regime of the process is a special down-flow reactor system, high reaction temperature, short contact time, and high catalyst/oil ratio. Experimental runs were conducted in a downer and riser-type pilot plants (capacity 0.1 BPD) and a demonstration plant (capacity 30BPD) using various catalysts, additives, and feed oils. Pilot plant results demonstrated the advantage of downer in suppressing back-mixing, thus increasing the yield of light olefins and reducing dry gas. Using paraffinic crude base vacuum gas oil (VGO), propylene yield of 25wt% was obtained under HS-FCC reaction conditions.

Sulfur Reduction in FCC Gasoline with a Commercial Additive: A Microactivity Study

Abstract The use of advanced FCC catalysts and additives to reduce sulfur in gasoline remains the preferred option to refiners because of its economic and operation incentives. The performance of a commercial sulfur-reducing additive blended with a fresh RE-USY catalyst was assessed in a microactivity (MAT) unit using Arabian Light vacuum gas oil (VGO). The additive was evaluated at different concentrations (0–15 wt%) in terms of sulfur reduction capability and its effect on product yield structure, mainly gasoline. At 5 wt% additive, the results showed a 14 wt% reduction in total gasoline sulfur with minor effect on catalytic activity and product selectivity. Minimal reduction capability was observed towards benzothiophene (BT), which is difficult to crack and remove under cracking conditions. Upon increasing additive concentration to 10 wt%, total sulfur was reduced to 21 wt% compared to 27 wt% reduction at 15 wt% additive. At this additive concentration, aromatic sulfur compounds mainly C4-thiophenes and a portion of BT were cracked to tetrahydrothiophene, or thiophene, which were subsequently cracked to H2S and light gases.