Structure variations of carbonizing lignin

¹ Centro Técnico Aeroespacial-IPD-PMR, São José dos Campos, S. Paulo, Brazil.
² Instituto de Fisica e Quimica de Sao Carlos, São Carlos, S. Paulo, and Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, R, Janeiro, Brazil.

Abstract

The studied lignin is a by-product of the process of ethanol production from eucaliptus. It was heat-treated under inert atmosphere conditions at increasing temperatures from 300 °C up to 2400 °C. The structural variations were studied by wide-angle X-ray diffraction, small-angle X-ray scattering and infra-red absorption spectroscopy. The bulk and “real” density of the compacted materials have also been determined as a function of the final temperature. These experimental results enabled us to establish a mechanism of structure variation based on the formation of a graphite-like and porous structure within the initially amorphous lignin matrix.

Résumé

La lignine étudiée est un sous-produit de la production d'éthanol à partir d'eucalyptus. L'évolution structurale produite par traitement thermique jusqu'à 2400 °C est étudiée à l'aide de la diffraction X, de la diffusion aux petits angles de la spectroscopie IR, et de mesures de densité. Un mécanisme de changement de structure est proposé, basé sur la formation d'une structure graphitique poreuse au sein de la matrice amorphe de lignine.