Maximizing Propylene Yield by Two-Stage Riser Catalytic Cracking of Heavy Oil

Abstract

The two-stage riser catalytic cracking for maximizing propylene yield has the following characteristics: relative lower temperature with larger catalyst/oil ratio, stratified injections of various feedstocks, and proper contacting time between catalyst and oil vapor. These characteristics can enhance catalytic cracking and minimize thermal cracking, which is very favorable for maximizing propylene yield and lowering dry gas. The experimental results showed that using the special catalyst LTC-2 the yield of propylene is up to 24.11% and the liquid yield approaches 82% when the first stage riser is fed Daqing AR with butenes and the second is fed the light gasoline and heavy oil from the first stage. The final gasoline containing only 26% olefins and nearly 50% aromatics is the desired high octane-number component. The diesel must be hydrogenated due to its higher density.