Cellulose Structural Changes during Mild Torrefaction of Eucalyptus Wood

Area of Science:

• Wood Science
• Materials Science
• Biomass Chemistry

Background:

• Cellulose structure is crucial for biomass properties.
• Torrefaction alters biomass composition and structure.
• Understanding cellulose changes during torrefaction is key for biomass utilization.

Purpose of the Study:

• To investigate the structural and molecular changes in cellulose from eight Eucalyptus species after mild torrefaction.
• To assess the impact of torrefaction on cellulose crystallinity and molecular weight.
• To explore the role of lignin in cellulose modifications during heat treatment.

Main Methods:

• Solid-state carbon nuclear magnetic resonance (¹³C NMR)
• Wide angle X-ray scattering (WAXS)
• Fourier transform infrared spectroscopy (FTIR)
• Analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS)
• Viscosimetry

Main Results:

• Mild torrefaction (160-230 °C) caused a slight decrease (2-3%) in cellulose crystallinity, attributed to amorphization and bond cleavage.
• The degree of cellulose polymerization (DPv) more than halved during torrefaction.
• Lignin content may influence the observed changes in cellulose supramolecular structure and molecular weight.

Conclusions:

• Mild torrefaction significantly degrades cellulose molecular weight and polymerization.
• Cellulose crystallinity shows minor reduction, with limitations in detecting these changes using FTIR and Py-GC/MS.
• Further research is needed to fully elucidate the role of lignin in torrefaction-induced cellulose modifications.