(185b) Re-Thinking Benzene Control Strategies to Maximize Octane

Limiting production by precursor removal from naphtha reformer feed or post reformer segregation and destruction by saturation are strategies that have been widely deployed to meet gasoline benzene limits required by EPA's MSAT 2 rule. These strategies not only reduce pool octane by limiting benzene but also tend to restrict naphtha reformer severity which in turn reduces availability of higher carbon number aromatics.

Vehicle manufacturers are zeroing in on higher octane for higher compression engines as a primary compliance strategy to meet fuel efficiency standards. Studies have shown that meeting the higher anticipated octane levels requires more octane boost than can be achieved by light naphtha isomerization and/or C4 alkylation. Higher severity naphtha reforming is the pathway for refiners to deliver higher octane but before that can happen the reformer severity constraint imposed by MSAT2 benzene limits must be removed.

This paper will discuss alternative processing strategies including benzene recovery by solvent extraction and propylene alkylation of benzene that can be deployed for benzene compliance as well as to meet higher octane for improved fuel economy.