Investigation of deactivation mechanisms of a solid acid catalyst during esterification of the bio-oils from mallee biomass

The oligomers, N-containing organics and metal ions in bio-oil poison the solid acid catalyst via different ways. Processing with a concentrated sulfuric acid significantly improved the catalytic activity via removal of the poisons. [Display omitted] •Deactivation of a solid acid catalyst in bio-oil esterification was investigated.•The bio-oils from wood, bark, and leaves contain quite different catalyst poisons.•Metal ions, N-containing organics and polymer in bio-oil poison catalyst.•Ion exchange can substantially but not completely regenerate the catalyst.•Metal ions and N-containing organics are reversible poisons while polymer is not. This study reports the deactivation mechanisms of the solid acid catalyst Amberlyst 70 during the esterification of bio-oils from mallee biomass and the methods for catalyst regeneration. The metal ions in bio-oil deactivated Amberlyst 70 via ion exchange with the hydrogen ions on/in catalyst, which changed structure of catalysts and reduced availability of acidic sites. N-containing organics reacted with the hydrogen ions on/in catalyst, forming neutral salts and resulting in complete catalyst deactivation. Polymers formed during the esterification of bio-oils deposited on/in catalyst, reducing the accessibility of catalytic sites. Washing with solvents could remove some adsorbed organics and restore some catalytic activity but not much. In comparison, ion exchange in a concentrated sulfuric acid removes most of metal ions and the N-containing organics and significantly improves the catalytic activity.