High severity FCC: A novel process for the production of light olefins and high-octane gasoline

The features of a novel high-severity FCC (HS-FCC) process in enhancing light olefins and gasoline production at high conversion were presented. The configuration of HS-FCC included a downer-reactor system operating at high reaction temperatures, higher catalyst/oil ratios, and short contact time. The production of C₂-C₄ light olefins in the downer was relatively high at 23 wt % but lower than the riser due to gasoline over-cracking in the riser. Higher selectivity of gasoline in the downer system was attributed to a lower back-mixing in the downer. The yields of dry gas and 1,3-butadiene that were typical products from thermal cracking, indicating that thermal cracking of hydrocarbon was effectively suppressed in a downer reactor. Yields of dry gas, coke, and 1,3-butadiene in the downer reactor were much lower compared to the riser reactor. The results confirmed reduced effects of thermal cracking and back-mixing in the downer system configuration.