Residue Catalytic Cracking Process for Maximum Ethylene and Propylene Production

Effects of operating conditions on residue fluid catalytic cracking (RFCC) were studied in a pilot-scale FCC unit. Experimental results indicated that both high reaction severity and long residence time promoted the production of ethylene and propylene. A novel RFCC process for maximum ethylene and propylene (MEP) production was further proposed, which was characterized by high operating severity, application of olefin-selective catalyst, and stratified reprocessing of light gasoline and butenes. Simulation experiments of the MEP process demonstrated that both light cycle gasoline and recycled butenes were effectively converted; meanwhile, the semispent catalyst still retained sufficient activity to further crack residue feedstock. When treating Daqing AR, the MEP process yielded up to 8.85 wt % ethylene and 25.97 wt % propylene. In contrast, due to elevated catalyst activity in a second-stage riser, the two-stage riser MEP process produced more propylene and LPG at the expense of light oil. Also, ethylene yield was still up to a comparative level.