Gasification of guaiacol in supercritical water: Detailed reaction pathway and mechanisms

Supercritical water gasification of guaiacol as a model compound for lignin was conducted in quartz reactors. The formation and degradation pathways of intermediates were discussed. The results show that the gasification efficiency of guaiacol in supercritical water increased as the reaction time increased. The intermediates in the residual liquid consisted mainly of phenols, arenes, cyclopentanones, alcohols and organic acids. Phenols and arenes were difficult to be gasified in supercritical water and easily turned into char and tar while cyclopentanones, alcohols and organic acids could be easily gasified and turn into hydrogen-rich gas. The Ru/Al₂O₃ catalyst promoted the degradation of phenols and arenes and thus inhibited the formation of char and tar.