BASF’s Melissa Clough noted in her presentation during the RefComm® refining conference FCC session on Wednesday that 90% of sulfur in gasoline is derived from FCC gasoline. This condition has been dealt with by refiners for at least the past five years. Clough added to this narrative that in 2011, only about two countries were meeting 10 ppm sulfur limits in their gasoline pool. Now most countries are close to achieving the 10 ppm sulfur limit, but that milestone comes at a heavy price.
Not only has sulfur been significantly reduced, but octane value has been compromised as well. In addition, those refiners attacking the sulfur limit challenge by way of operational adjustments, notably with adjusting cut points (undercutting) to push sulfur into LCO, is a reason why FCC gasoline volumes have recently dropped by 16%. Clough mentioned that in 2009, 22% of refiners were employing an undercutting “strategy,” whereas 68% of refiners are expected to incorporate undercutting as part of their sulfur reduction strategy by 2018.
With the EPA Tier 3 sulfur in gasoline limits approaching by January 1, octane preservation of hydrotreated FCC gasoline is an important consideration for weighing the benefits of low sulfur additives, such as BASF’s LSA additive. There are various compelling reasons for considering an FCC additive treatment program, such as when the refinery’s hydrotreating operations are hydrogen limited. During a turnaround and temporary shutdown of an FCC pretreater or FCC gasoline post-treater, having an LSA treatment strategy can mitigate the loss in hydrotreating capacity, thereby achieving the less than 10 ppm sulfur reduction target while preserving octane.