CHARACTERIZATION AND CATALYTIC GASIFICATION OF THE AQUEOUS BY-PRODUCTFROM VACUUM PYROLYSIS OF BIOMASS

Spruce wood residues were treated in a vacuum pyrolysis Process Develo pment Unit with a throughput capacity of 28 kg/h. Two aqueous phase co ndensate samples with COD concentration varying between 190 and 255 g/ L were produced and sequentially extracted with dichloromethane and et hylacetate solvents. The soluble organic matter was composed of acidic , phenolic, alcoholic and ketonic compounds. The insoluble fraction wa s sequentially distilled at 100 and 110-degrees-C under atmospheric pr essure. Mainly water was recovered in the first distillate, while the second distillate contained 30.4% formic and acetic acids, 69.4% water and 0.2% residual organic compounds. The distillation residue was ric h in oxygen and was essentially insoluble in any organic solvent. The two aqueous phase pyroligneous samples were treated in Battelle's Ther mochemical Envirornmental Energy System (TEES(R)), a registered servic e mark of OnsiteOfsite, Inc. of Duarte, California, U.S.A. The result s of the tests showed that similar results were obtained with either f eedstock. In batch tests a COD reduction of 99% was achieved. The prod uct gas composition was typically about 49 % methane, 5 % hydrogen, 1% ethane and 45% carbon dioxide. Tests in a continuous stirred-tank rea ctor produced reproducible data which can be used for process scale-up . Catalyst lifetime was identified as needing further improvement. The preliminary results demonstrated the technical feasibility of the cat alytic gasification process as a useful step in the recovery of energy from the secondary condensate stream and the cleanup of the by-produc t water from vacuum pyrolysis of wood.