Octane improvement update -Refinery processing, antiknocks, and oxygenates

Octane improvement of gasoline encompasses a broad range of processing flexibility, additives, and blending materials in today's refining scheme. Conventional hydrocarbon streams, derived primarily from the fluid cat cracker and the naphtha reformer, are currently more adjustable with respect to octane quality because of low utilization of refinery capacity. Both units can be used to upgrade the gasoline pool. Traditional antiknocks can be used singly and in various combinations in leaded gasoline to legal limits. Alcohols and ethers can be used as individual blending agents and in various combinations in leaded gasoline and in unleaded gasoline as limited by the U.S. Environmental Protection Agency regulations. Maximum utilization of antiknocks -- the lowest-cost flexible source of octane quality -- is still the fundamental cushion for economic regulation of octane quality in the total gasoline pool. However, the key to maximum profit from all finished gasoline grades on a sustained basis is constant surveillance of options for octane improvement. This includes a regular assessment of the current and future availability of alternatives to antiknocks. The purpose of this paper is to update this background for the petroleum refiner.