Process Economics Program Report 169B
Petrochemicals From Refinery Streams
Published: February 2000
Lyondell� s (formerly Arco� s) SuperflexSM process and Mobil� s Olefin Interconversion (MOI) process are two new secondary olefin conversion technologies that crack C4-C8 olefins to predominately ethylene and propylene. Both technologies are based on a reactor/regenerator design similar to conventional fluid catalytic cracking (FCC). Alternatively, Asahi� s Alpha process converts C4-C8 olefins to aromatics, mainly benzene, toluene, and xylenes (BTX). In the Alpha process, hydrogen circulation maintains stable catalyst activity for 3 days; therefore, this process can operate in a two-fixed bed swing reactor system.
Shape-selective medium-pore zeolite catalysts are at the heart of the three processes. Reaction thermodynamics determine the product slate and selectivity independent of feedstock sources. Suitable feedstocks include light cracked naphtha (LCN), coker naphtha, steam cracker C4/C5, and light pyrolysis gasoline.
Olefin cracking technology offers the opportunity to decouple propylene supply from ethylene production. The quantity of polymer-grade propylene produced by either the Superflex or MOI process based on LCN from a 65,000 b/d FCC unit exceeds that recovered from a 1 billion lb/yr (world-scale) naphtha-based ethylene plant. A similar amount of LCN could produce BTX equivalent to that of a 44,5000 b/d catalytic reformer.