Octane Enhancement

Enterprise owns and operates an octane enhancement production facility located in Mont Belvieu, Texas that is designed to produce isooctane, a motor gasoline octane enhancement additive used in reformulated motor gasoline blends to increase octane, isobutylene and methyl tertiary butyl ether ("MTBE"). The high-purity isobutane feedstocks consumed in the production of these products are supplied by our isomerization units. To the extent that MTBE is produced at our Mont Belvieu facility, it is strictly sold into the export market.

In November 2010, we purchased a facility located on the Houston Ship Channel that produces high purity isobutylene ("HPIB"). The feedstock for this plant is produced by our octane enhancement facility in Mont Belvieu, Texas. High purity isobutylene is used in the production of alkylated phenols used as antioxidants, lube oil additives, butyl rubber and resins.

Facility	Ownership Interest	Capacity (MBPD/day)	Operator
Mont Belvieu	100%	12	Enterprise
Houston Ship Channel(1)	100%	4	Enterprise