Technical key and practice of producing high octane number gasoline or light aromatics (LTAG) from FCC light cycle oil

Based on the knowledge of hydrocarbon composition molecular level characterization of FCC light cycle oil (LCO), the hydrogenation reaction regularity of polycyclic aromatic hydrocarbons(PAHs) in LCO, and the catalytic cracking and hydrogen transfer reactions characteristics of monocyclic aromatic hydrocarbons(MAHs) like tetralin compounds in hydrotreated LCO, LCO to aromatics or gasoline with high octane number (LTAG) technology was successfully developed. The LTAG technology is the integration technology of LCO selective hydrogenation and fluidized catalytic cracking. The key of LTAG technology is to generate MAHs like tetralin compounds from PAHs in LCO by selective hydrogenation saturated reaction. Then by strengthening hydro-LCO catalytic cracking reaction and inhibiting the hydrogen transfer reaction, hydro-LCO can be converted efficiently to high octane number gasoline or light aromatics. LCO can be hydrogenated individually, or mixed with vacuum gas oil (VGO) or residue oil in hydrogenation unit. Two models could be used in catalytic cracking unit: (1) The high-octane number gasoline fraction or light aromatics is produced by hydro-LCO individual catalytic cracking. (2) The high octane number gasoline fraction can be produced by hydro-LCO and heavy oil feedstock stratified sequential feeding. LTAG technology supports greatly for refineries to reduce the diesel to gasoline ratio, adjust products mix, and enhance products quality. It not only provides a way out for inferior LCO, but also makes up the shortage of high octane number gasoline fraction and light aromatics. Therefore, LTAG has apparent economic benefits and has been widely applied in refineries.