Process optimization for enzymatic production of a valuable biomass-based ester from levulinic acid

Area of Science:

• Biocatalysis and Green Chemistry
• Biomass Conversion and Valorization
• Enzyme Immobilization and Engineering

Background:

• Levulinic acid (LA) is a key biomass-derived platform chemical with diverse applications.
• Esterification is a crucial reaction for producing valuable esters, such as isoamyl levulinate.
• Developing sustainable and efficient catalytic systems for ester production remains a significant challenge.

Purpose of the Study:

• To develop an enzymatic process for synthesizing isoamyl levulinate from LA and isoamyl alcohol (IA).
• To immobilize a low-cost commercial lipase onto a mesoporous support for use as a heterogeneous biocatalyst.
• To optimize reaction conditions and evaluate the green credentials of the proposed esterification process.

Main Methods:

• Immobilization of Eversa® Transform 2.0 lipase onto poly(styrene-divinylbenzene) beads via physical adsorption.
• Optimization of esterification reaction parameters (biocatalyst loading, temperature, substrate ratio) using Central Composite Rotatable Design (CCRD).
• Evaluation of biocatalyst reusability and process greenness using EcoScale.

Main Results:

• High protein loading (31.2 ± 2.8 mg/g) and immobilization yield (83%) were achieved.
• Optimal conditions yielded 65% acid conversion in 12 hours at 40°C with 20% biocatalyst loading and a 1:1.5 LA:IA ratio in MIBK.
• The immobilized biocatalyst retained 30% activity after five cycles, and the process achieved an EcoScale score of 66.5.

Conclusions:

• A cost-effective and sustainable heterogeneous biocatalyst was successfully prepared for isoamyl levulinate synthesis.
• The optimized enzymatic process offers an efficient route for producing a valuable industrial ester from biomass-based resources.
• The developed method represents a promising green alternative for ester production, aligning with principles of sustainable chemistry.