PEP Review 99-4
Catalytic Cracking of Light Cracked Naphtha to Produce Propylene
Published: May 2002
This review examines Fina Research's patent WO 99/29805 which discloses a catalytic cracking process for converting C5-C8 olefins in a light cracked naphtha to lighter olefins, primarily propylene. Effective catalysts for this endothermic conversion are highly dealuminated silicalite type zeolites (e.g. ZSM-5). Laboratory scale experiments are provided demonstrating that the conversion occurs efficiently under adiabatic conditions at a reactor inlet temperature of ~1000oF, ambient pressure and at relatively high space velocity (LHSV 10-1 h). 78 wt% of the C5-C8 olefins in a typical LCN feed were converted to lighter olefins, mostly propylene, with only a minor change in the paraffins and aromatics fractions. It was also demonstrated that catalyst activity can be maintained for more than 100 hours provided the LCN feed is hydrotreated to reduce diene levels to less than 300 ppm.).