A review on catalytic & non-catalytic bio-oil upgrading in supercritical fluids

Sainab Omar, Yang Yang, Jiawei Wang

Research output: Contribution to journalReview articlepeer-review


This review article summarizes the key published research on the topic of bio-oil upgrading using catalytic and non-catalytic supercritical fluid (SCF) conditions. The precious metal catalysts Pd, Ru and Pt on various supports are frequently chosen for catalytic bio-oil upgrading in SCFs. This is reportedly due to their favourable catalytic activity during the process including hydrotreating, hydrocracking, and esterification, which leads to improvements in liquid yield, heating value, and pH of the upgraded bio-oil. Due to the costs associated with precious metal catalysts, some researchers have opted for non-precious metal catalysts such as acidic HZSM-5 which can promote esterification in supercritical ethanol. On the other hand, SCFs have been effectively used to upgrade crude bio-oil without a catalyst. Supercritical methanol, ethanol, and water are most commonly used and demonstrate catalyst like activities such as facilitating esterification reactions and reducing solid yield by alcoholysis and hydrolysis, respectively.
Original languageEnglish
Pages (from-to)4–17
Number of pages14
JournalFrontiers of Chemical Science and Engineering
Issue number1
Early online date10 Jun 2020
Publication statusPublished - Feb 2021

Bibliographical note

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  • bio-oil
  • review
  • supercritical
  • upgrading


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