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Publication Date: 2012-May-08

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KBR Paper No 1737


Ronald Birkhoff

Kellogg Brown& Root, Inc. (KBR)

Matti Nurminen

Fortum Oil and Gas Oy.


Environmental issues are threatening the future use of MTBE (methyl-tert-butyl ether) in gasoline in the United States. Since the late 1990'sconcerns have arisen over ground and drinking water contaminationwith MTBE due to leakingofgasolinefrom underground storage tanks and the exhaust from two-cycle engines. In California a number of cases of drinking water pollutionwith MTBE haveoccurred. As a result, the elimination of MTBEin gasoline in Californiawas mandated, and legislation is now set to go in effect by the end of 2003. The U.S. Senate has similar lawunderpreparation,whichwould eliminateMTBE inthe 2006-2010 timeframe.

With an MTBEphase-out imminent,U.S. refinersare faced with the challenge of replacingthe lost volume and octane value of MTBE in the gasoline pool. In addition, utilization of idled MTBE facilities and the isobutylene feedstock result in pressing problems of unrecovered and/or under-utilized capital for the MTBEproducers. Iso-octane hasbeenidentified as a cost effective alternativeto MTBE. Itutilizesthe same isobutylenefeeds usedinMTBE production, and offers excellent blendingvalue. Furthermore, iso-octaneproduction can be achieved ina low-cost revamp of an existing MTBE plant. However, since iso-octaneisnotan oxygenateit does not replace MTBE to meet the oxygen requirementcurrently in effect for Reformulated Gasoline.

The NExOCTANETechnology was developedfor the productionof iso-octane. Inthe process, isobutylene is dimerized to produceiso-octene,which cansubsequently behydrogenatedto produce iso-octane. Bothproductsare excellent gasolineblendstockswith significantlyhigher product value than alkylate or polymerizationgasoline.

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During the 199O's, MTBE was the oxygenate of choice for refiners to meet increasingly stringent gasoline specifications. In the United States and in a limited number of Asian countries the useofoxygenatesingasoline was mandatedto promotecleaner-burning fuels In addition, lead phase-downprograms inotherpartsofthe world haveresultedinan increased demand for high octane blendstock.All this resultedina strong demandfor high-octanefuel ethers, and significant MTBE production capacity has been installed since 1990.

Today, the United States is the largest consumer of MTBE. The consumption increased dramatically with the amendment of the Clean Air Act in 1990 which incorporatedthe 2% oxygen mandate. The MTBE productioncapacity more than doubled in the five year period from 1991-1995. By 1998,the MTBEdemand growth had leveledoff, and has since tracked the demand growth for Reformulated Gasoline (RFG). The United States consumes about 300,000 bpdof MTBE,of which over 100,000bpd isconsumed inCalifornia.The U.S. MTBE consumption is about 60% of the total world demand.

MTBEisproducedfrom isobutyleneand meth...