Simulating the Rapid Devolatilization of Mineral-Free Lignins

Area of Science:

• Biomass Conversion
• Chemical Engineering
• Materials Science

Background:

• Lignin devolatilization is crucial for biomass conversion.
• Understanding lignin's molecular structure impacts product yields.
• Existing models require further validation across diverse lignin types.

Purpose of the Study:

• Expand validation of the Lig-FC model for lignin primary devolatilization.
• Assess the influence of lignin quality and processing parameters on product distribution.
• Correlate lignin molecular weight distribution (MWD) with oil and char yields.

Main Methods:

• Validated the Lig-FC model using data from 27 mineral-free lignin samples.
• Tested a wide range of conditions: temperatures to 1150 °C, heating rates 30–8000 °C/s, contact times up to 90 s, and pressures from vacuum to 0.13 MPa.
• Analyzed the impact of lignin MWD, heating rate, temperature, contact time, and pressure on product yields and oil molecular weight distributions.

Main Results:

• Lig-FC accurately predicts the effects of lignin quality and processing parameters on major products and oil MWDs.
• Lignin MWD is a key factor, with lighter MWDs yielding more oils during flash distillation.
• Higher oil yields and lower char yields were observed for lighter lignin MWDs and those richer in H relative to O.

Conclusions:

• The Lig-FC model provides a robust framework for predicting lignin devolatilization outcomes.
• Lignin molecular weight distribution is a critical determinant of oil and char yields.
• Optimizing lignin feedstock selection and processing conditions can enhance valuable oil production.