Upgrading Bio-oil over Different Solid Catalysts

Solid acid 40SiO2/TiO2−SO42- and solid base 30K2CO3/Al2O3−NaOH were prepared and compared with catalytic esterification activity according to the model reaction. Upgrading bio-oil by solid acid and solid base catalysts in the conditioned experiment was investigated, in which dynamic viscosities of bio-oil was lowered markedly, although 8 months of aging did not show much viscosity to improve its fluidity and enhance its stability positively. Even the dehydration by 3A molecular sieve still kept the fluidity well. The density of upgraded bio-oil was reduced from 1.24 to 0.96 kg/m3, and the gross calorific value increased by 50.7 and 51.8%, respectively. The acidity of upgraded bio-oil was alleviated by the solid base catalyst but intensified by the solid acid catalyst for its strong acidification. The results of gas chromatography−mass spectrometry analysis showed that the ester reaction in the bio-oil was promoted by both solid acid and solid base catalysts and that the solid acid catalyst converted volat...