Different solid acid catalysts influence on properties and chemical composition change of upgrading bio-oil

Several solid acid catalysts are prepared and compared in upgrading bio-oil using ethanol and acetic acid as raw materials through the catalytic esterification reaction model. The SO42−/SiO2–TiO2 catalyst in the optimum experimental conditions achieved higher catalytic activity. The bio-oil was stabilized by ester reaction over SO42−/SiO2–TiO2 catalyst in the conditioned experiment with lowered dynamic viscosity and enhanced fluidity, which was sustained after aging for 6 months in a refrigerator under about 5 °C. The gas chromatography–mass spectrometry analysis of the composition before and after the catalytic esterification proved that the proportion of esters in the upgraded bio-oils increased remarkably, suggesting that the catalytic esterification can vary the composition and properties obviously thus enhances the stability of bio-oil.