UPGRADING OF WOOD-DERIVED BIO-OIL OVER HZSM-5

The upgrading of a bio-oil obtained by the high-pressure liquefaction of aspen wood was studied over HZSM-5. A fixed-bed microreactor, operated at atmospheric pressure and in the temperature range 370-410-degrees-C was used. The oil was co-fed with diluents such as tetralin, steam and methanol. The upgraded product contained a large percentage of benzene, toluene, xylene and other hydrocarbons as liquid. The amount of pitch in the product decreased by 70-80% wt from that in the oil. In all the experiments, the phenolic content of the bio-oil decreased whereas the amount of aromatic hydrocarbons increased significantly to a maximum value. The amount of gas product was usually less than 5% wt. At high temperatures, over 30% wt of the oil remained as coke on the catalyst. A reaction scheme is postulated based on the results.