Study of the potential valorisation of heavy metal contaminated biomass via phytoremediation by fast pyrolysis: Part II: Characterisation of the liquid and gaseous fraction as a function of the temperature C. Lievens, J. Yperman * , T. Cornelissen, R. Carleer Laboratory of Applied Chemistry, CMK, University Hasselt, Campus Diepenbeek, Agoralaan, Building D, 3590 Diepenbeek, Belgium Received 18 July 2007; received in revised form 19 October 2007; accepted 24 October 2007 Available online 21 November 2007 Abstract Fast pyrolysis of heavy metal contaminated birch (CMB), resulting from phytoremediation, is investigated. The effect of the pyrolysis temperature (673, 773, 873 K) on the composition and evolution of the bio-oil/tar fraction and the gas fraction has been studied. The knowledge of the composition of the gaseous and liquid pyrolysis fractions, as a function of the pyrolysis temperature, affects directly future applications and valorisation of the pyrolysis products and are indispensable for making and selecting the proper thermal condi- tions for their optimal use. In view of the future valorisation of this heavy metal contaminated biomass, the pyrolysis temperature is imperative, because some of the heavy metals can volatilize at temperatures generally used for the co-combustion or fast pyrolysis of biomass. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Fast pyrolysis; Biomass; Phytoremediation 1. Introduction Nowadays, there is a great concern with environmental problems associated with increased CO 2 , NO x and SO x emissions resulting from the rising use of fossil fuels. For this reason, more attention is being paid to renewable energy, especially biomass energy [1]. Pyrolysis is a thermal degradation process (cracking) of biomass using heat in the absence of oxygen, which results in the production of char (solid), bio-oil and tar (liquid), and fuel gas products [2]. Pyrolysis has widely been applied to a number of biomass species. The pyrolysis products of birch wood have been the subject of many investigations: e.g. reactivity of the pyrolysis char [27]. Zanzi et al. [28]. studied the effect of the process conditions on characterisa- tion of the char and gas composition. Different types of pyrolysis are used (slow, fast and flash pyrolysis), depending on the objective. Lower process temperature and longer vapour residence times favour the production of charcoal. High temperature and longer resi- dence time increase the biomass conversion to gas. Moder- ate temperature and short vapour residence time are optimum for producing liquids. For the production of liquids, fast pyrolysis is particularly interesting [3–5]. The liquid product, bio-oil, has the advantages that it can readily be stored and transported, and/or being directly used as a fuel or for the isolation or upgrading of chemicals with added value [6]. The pyrolysis liquid products contain a significant amount of water, thus it is necessary that the resultant liquid product would need further processing to remove the reaction/pyrolytic water for chemical feedstock and/ 0016-2361/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2007.10.023 * Corresponding author. Tel.: +32 11 268 320; fax: +32 11 268 301. E-mail address: jan.yperman@uhasselt.be (J. Yperman). www.fuelfirst.com Available online at www.sciencedirect.com Fuel 87 (2008) 1906–1916