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EP 0 616 633 A1

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(43) Date of publication: 28.09.1994 Bulletin 1994/39 (21) Application number: 93900921.0 (22) Date of filing: 08.12.1992

(51) International Patent Classification (IPC):  C10G 59/ 02( . ) (86) International application number: PCT/US1992/010538 (87) International publication number: WO 1993/012203 (24.06.1993 Gazette 1993/15)

(84) Designated Contracting States: BE DE FR GB IT NL (30) Priority: 09.12.1991 US 19910805334 09.12.1991 US 19910805360 (71) Applicant: EXXON RESEARCH AND ENGINEERING COMPANY Florham Park, New Jersey 07932-0390 (US)

(72) Inventors: GOLDSTEIN, Stuart S. Ewell, Surrey KT17 3JS (GB) KAMIENSKI, Paul, W. Basking Ridge, NJ 07920 (US) STAUBS, David, W. Morris Plains, NJ 07950 (US) SWART, Gerritt, S. Westfield, NJ 07090 (US) SWAN, George, A., III Baton Rouge, LA 70817 (US) CLEM, Kenneth, R. Humble, TX 77436 (US) (74) Representative: Somers, Harold Arnold, et al  ESSO Engineering (Europe) Ltd. Patents & Licences Mailpoint 72 Esso House Ermyn Way Leatherhead, Surrey KT22 8XE Leatherhead, Surrey KT22 8XE (GB)