Reaction Analysis of Diaryl Ether Decomposition under Hydrothermal Conditions

David Alam, Matthew Y. Lui, Alexander Yuen, Thomas Maschmeyer, Brian S. Haynes, Alejandro Montoya*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

7 Citations (Scopus)

Abstract

The reactivity and decomposition pathway of models for α-O-4 and β-O-4 linkages, found within lignin, have been examined using methoxy-substituted (-OCH3) and -unsubstituted (-H) aryl groups under hydrothermal conditions. α-O-4 model compounds readily underwent conversion at comparatively mild temperatures (140-300 °C) and short reaction times (5-80 min), in contrast with the β-O-4 containing model compounds which required temperatures up to 340 °C and longer reaction times up to 240 min. Pseudo-first-order rate constants and apparent activation energies were calculated for hydrothermal conversion of the model compounds based on experimental data. The cleavage of these linkages proceeded via hydrolysis and direct elimination pathways, with the resulting products prone to undergoing further reactions including condensation, and dehydration. The presence of methoxy functionalities on the aromatic rings was found to destabilize both the α-O-4 and β-O-4 ether linkages, decreasing the temperature and reaction times required to decompose them under hydrothermal conditions. In addition, the methoxy substituents were partially hydrolyzed under hydrothermal conditions at temperatures exceeding 280 °C, resulting in a number of substituted guaiacol products.

Original languageEnglish
Pages (from-to)2014-2022
Number of pages9
JournalIndustrial and Engineering Chemistry Research
Volume57
Issue number6
DOIs
Publication statusPublished - 14 Feb 2018

Scopus Subject Areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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