Comparative study on char properties and pyrolysis kinetics of different lignocellulosic wastes.

P. R. BONELLI; P. A. DELLA ROCCA; E. G. CERRELLA; A. L. CUKIERMAN

Progress in Thermochemical Biomass Conversion

Blackwell Science London, UK

Lugar: London, UK; Año: 2001; p. 1116 - 1128

Chemical composition, heating values and surface properties of the char samples generated from slow pyrolysis of different abundant lignocellulosic wastes under identical operating conditions were examined to assess comparatively their suitability for potential use as biofuel and/or for further processing to produce activated carbons. Sawdust from two different wood species (Aspidosperma australe, Populus deltoide), peanut husks, and olive stones were selected. Proximate and ultimate analyses as well as physical adsorption measurements of nitrogen and carbon dioxide were perfomed. Heating values were estimated from a multivariate correlation in terms of samples` elemental composition. All the chars obtained are found potentially useful as relatively pollution-free solid biofuels, the char arising from sawdust of Aspidosperma wood having the greatest potential. Comparison of surface properties with those determined for the olive stones-char, taken as a reference, suggests that the chars from peanut husks and from sawdust of Populus wood could be potential adequate candidates for further conversion into activated carbons. Kinetic measurement of the wastes pyrolysis were additionally conducted by non-isothermal thermogravimetry over the temperature range 25°C ~900°C. Kinetic parameters were estimated by applying a published model, which assumes a steadily increasing  variation in the activation energy with the course of pyrolysis and allows effective representation of experimental data for all the selected wastes over the whole range of temperature. Appreciable differences in the estimated kinetic parameters are found.