Isomerization in Petroleum Processing

Upgrading light hydrocarbon (C₄–C₇) streams in refineries, petrochemical plants, and gas processing plants has continued to increase in commercial application, as the world demand for gasoline and petrochemicals has experienced steady growth over the past decade. Increasingly stringent regulations have been enacted in most regions of the world, driving the increased demand for clean fuels. As a result, gasoline composition has been adjusted to a greater extent using C₅–C₇ isomerization processes. Light-naphtha isomerization technology plays a key role in meeting octane demand in the gasoline pool for clean fuels and premium gasoline grades. Low octane naphtha feedstocks are processed into isomerate with an octane number ranging from 80 to 93 RON. Isomerization involves the skeletal isomerization of a paraffin to a more highly branched paraffin with the same carbon number. Several light paraffin isomerization technologies are reviewed in this chapter, including both process and catalyst technologies. Flow schemes and economics are reviewed. Catalyst technologies include Pt containing zeolitic, mixed-metal oxide, and chlorided alumina.