Vacuum pyrolysis of bark residues and primary sludges

Black spruce bark residues and primary sludges derived from the operation of the Daishowa pulp and paper plant in Quebec City, PQ, were processed by vacuum pyrolysis in a laboratory-scale batch reactor. The pyrolysis oil, water, charcoal, and gas were recovered and analyzed. The bark residues yielded 30.6% oil and 34.1% charcoal, and the primary sludges gave 40.1% oil and 30.1% charcoal on a feedstock air-dry basis. The oil phases recovered from the two pyrolysis experiments were fractionated into eight fractions; they were analyzed by gas chromatography/mass spectrometry. Both pyrolysis oil samples had a high content of phenolic compounds. These oils contained various fine chemicals that have possible commercial potential. Aliphatic and aromatic hydrocarbons, as well as long- and short-chain carboxylic acids, are also present in both pyrolysis oils.