State of the art of applied fast pyrolysis of lignocellulosic materials - a review

Pyrolysis is the degradation of macromolecular materials with heat alone in the absence of oxygen. It has both analytical and applied aspects. The dev elopment of advanced fast pyrolysis processes for liquids production has ga ined much attention in the last decade, because they offer a convenient way to convert low value woody residues into liquid fuels and value-added prod ucts. This review describes the new pyrolysis reactors under development. T he systems based on (bubbling) fluidized bed and circulating fluidized bed reactors are presented. Moreover, the principles of ablative pyrolysis tech niques such as the rotating blade and rotating cone reactors including the vortex system are outlined and a vacuum pyrolysis system, a recent technica l development, is also presented. The international activities within the I nternational Energy Agency and European Union are shortly outlined with spe cial emphasis on the chemical and physical properties of pyrolysis oils and the methods for their upgrading and utilization as fuel and chemical feeds tock. The pyrolysis liquids obtained in a yield of ca. 70% (based on dry wo od) are complex mixtures of oxygenated aliphatic and aromatic compounds. Th eir energetic utilization is being tested in burners, Diesel engines and tu rbines. Commercial applications exist in the field of production of food ar omas. Emerging areas of utilization are: additives for flue gas cleaning of coal combustion; acetic acid for chip production; adhesives; fuel enhancer s; specialty chemicals; and fertilizers. (C) 1998 Published by Elsevier Sci ence Ltd. All rights reserved.