Assessment of the thermal behavior of lignins from softwood and hardwood species

Matheus Poletto

doi:10.4067/s0718-221x2017005000006

Abstract

The thermal behavior of lignins from softwood and hardwood species has been investigated using thermogravimetry and differential scanning calorimetry. Klason Lignin from Pinus taeda and Klason lignin from Eucalyptus grandis were studied. The differential scanning calorimetry results showed that both Klason lignins studied presented similar glass transition temperature. Thermogravimetric results showed that the lignin degradation occurs in three stages. The Klason lignin of Pinus taeda is more thermally stable than Eucalyptus grandis, probably because of the higher thermal stability of the guaiacyl units in softwood lignin. The degradation of both lignins initiate by a diffusion process. However when the conversion values are higher than 0,1 the lignin degradation mechanism is a complex procedure and involves the degradation of a highly condensed aromatic structure formed at the previous degradation stages.

Highlights

The increased interest in the conversion of wood and its components for producing alternative fuels and chemicals necessitates a fundamental understanding of the main characteristics, composition, thermal behavior and processes involving pyrolysis of biomass (Ferdous et al 2002, Brosse et al 2010, Wang et al 2015)
In order to better understand the thermal degradation and pyrolysis kinetics of lignin and its correlation with their properties, this study investigates the differences in thermal behavior and degradation kinetics of two Klason lignins obtained from different tree species
The Differential scanning calorimetry (DSC) results showed that both Klason lignins studied independent of the wood specie presented similar glass transition temperature

Summary

Introduction

The increased interest in the conversion of wood and its components for producing alternative fuels and chemicals necessitates a fundamental understanding of the main characteristics, composition, thermal behavior and processes involving pyrolysis of biomass (Ferdous et al 2002, Brosse et al 2010, Wang et al 2015). Several methods have been developed to separate lignin from the other constituents of the lignocellulosic materials (Brosse et al 2010, Jiang et al 2010, Wang et al 2015). Since each separation method modifies to some degree the chemical structure of the naturally occurring lignin, so lignin is conventionally named

Methods

Results

Conclusion