Optimizing Catalytic Depolymerization of Lignin in Ethanol with a Day-Clustered Box-Behnken Design

Area of Science:

• Biomass Conversion and Valorization
• Catalysis and Chemical Engineering
• Sustainable Chemistry

Background:

• Lignin, a complex biopolymer, is a promising source for biobased aromatic compounds.
• Applications include fuel additives, resins, and bioplastics, driving demand for efficient conversion technologies.
• Catalytic depolymerization using supercritical ethanol offers a pathway to extract valuable phenolic monomers from lignin.

Purpose of the Study:

• To evaluate the viability of a lignin conversion technology through a stage-gate scale-up methodology.
• To optimize the catalytic depolymerization of lignin using supercritical ethanol and a CuMgAlOx catalyst.
• To analyze the impact of key process parameters on monomer yield and byproduct formation.

Main Methods:

• A day-clustered Box-Behnken design was employed for experimental optimization.
• Five input factors (temperature, lignin-to-ethanol ratio, catalyst particle size, catalyst concentration, reaction time) were investigated.
• Linear mixed models and response surface methodology were used to quantify relationships between input factors and output streams (monomer yield, THF-soluble, THF-insoluble/char).

Main Results:

• Key input factors and their interactions were found to be highly significant in determining the three output product streams.
• Qualitative relationships were established through mass balances and product analyses.
• Quantitative relationships were studied using linear mixed models with random intercept and maximum likelihood estimation.

Conclusions:

• The response surface methodology effectively predicted the yields of the output streams, validating the analysis.
• The study demonstrates the potential of catalytic depolymerization for producing biobased aromatics from lignin.
• The findings support the scale-up viability of this lignin conversion technology for industrial applications.