Upgrading of Bitumen by Hydrothermal Visbreaking in Supercritical Water with Alkali

Atsushi Kishita, Satoru Takahashi, Hirotaka Kamimura, Masami Miki, Takehiko Moriya, Heiji Enomoto

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)


A study was conducted to clarify the characteristics of the upgrading reaction of bitumene in supercritical water with alkali compared to pyrolysis, and to obtain more information on desulfurization in supercritical water with alkali. The main components of the oil produced were paraffins and aromatics for pyrolysis and supercritical water cracking with and without alkali. The visbreaking mechanisms may be the same or very similar. The time dependencies of the visbreaking and desulfurization reactions were similar, but the effects of water were opposite: visbreaking was more extensive with lower water content in a short reaction time, whereas desulfurization proceeded with high water content over a long reaction time. Many thiophenes were formed in the oil produced, but benzothiophene and dibenzothiophene were hardly detected in the case of supercritical water cracking with and without alkali. These thiophenes were relatively easily decomposed or desulfurized in the supercritical water with alkyl. Vanadium in the oil product decreased to sim; 10%. About 60% was found in the aqueous phase.

Original languageEnglish
Pages (from-to)215-221
Number of pages7
JournalJournal of The Japan Petroleum Institute
Issue number4
Publication statusPublished - 2003 Jul
Externally publishedYes


  • Bitumen
  • Desulfurization
  • Oil sand
  • Supercritical water
  • Upgrading
  • Vanadium

ASJC Scopus subject areas

  • Fuel Technology
  • Energy Engineering and Power Technology


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