CATALYTIC UPGRADING OF PYROLYSIS OIL

The upgrading of a fast pyrolysis bio-oil and its two fractions was studied at atmospheric pressure using HZSM-5 as catalyst. The two fractions were pyrolytic lignin (which remained after removing water-soluble components from the whole bio-oil) and resid oil (which remained after separating phenolic fraction from the whole bio-oil). The upgrading was done in the temperature range of 340-410-degrees-C in a fixed bed microreactor. The objective was to maximize the desired organic distillate product with a high concentration of aromatic hydrocarbons. The maximum organic distillate from the upgrading of whole bio-oil was 19 wt % of bio-oil and the highest concentration of aromatic hydrocarbons in the distillate was 83 wt %. With pyrolytic lignin and resid oil as the feeds, the maximum amounts of organic distillate were 30 wt % of pyrolytic lignin and 17 wt % of resid oil, respectively, and the highest concentrations of aromatics in the distillate were 76 and 87 wt %. Comparison of the results on uniform wood basis revealed that the aromatic yield was at maximum 11 wt % of wood from the whole bio-oil, 6.5 wt % from the pyrolytic lignin, and below 5 wt % from the resid oil. However, in the case of pyrolytic lignin and resid oil, nearly 60 wt % of the bio-oil was also obtained as useful chemical byproduct. A reaction scheme for the upgrading is postulated based on these results.