Cat naphtha sulfur management: undercut or not?
Several processing options can create a high-sulfur heavy cat naphtha that concentrates FCC sulfur into one stream
New U.S. regulations will place intense investment and economic
pressures on refinery processing to meet tighter
sulfur specifications for gasoline.1 Fluid catalytic
cracking (FCC) unit naphtha (cat naphtha) is the major
contributor to gasoline sulfur. Approximately 90%, or even
more, of current gasoline sulfur originates from cat naphtha.
Efforts to reduce cat-naphtha-sulfur content include:
- Pretreat the FCC feed to remove sulfur
- Increase sulfur conversion to hydrogen sulfide inside the
- Post treat FCC product to remove
Where is the sulfur? Since the 1940s,
refiners have known that the bulk of the sulfur concentrates in
the heavy end of the cat naphtha.11 - 14
Undercutting FCC naphtha is an obvious way to reduce sulfur
content. Undercutting includes both dropping naphtha down to
light cycle oil (LCO) and taking a separate heavy-naphtha
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