Sequential Synthesis Methodology in the Design and Optimization of Sustainable Distillation Sequences for Levulinic Acid Purification

Abstract

Levulinic acid is acknowledged as a significant high-value product derived from lignocellulosic biomass. Its acquisition involves acid hydrolysis, resulting in a challenging separation and purification process due to the formation of a dilute azeotropic mixture. This complexity renders separation costly and presents a hurdle for large-scale production. Various purification methods, including hybrid and intensified systems, have been proposed to address this issue. However, a systematic synthesis methodology incorporating multi-objective optimization considering economic and environmental factors has yet to be applied to this mixture. Hence, this study employs such a methodology to derive sustainable and thermodynamically feasible intensified designs. The optimization algorithm employed is differential evolution with a tabu list. Two objectives are considered: total annual cost as the economic criterion and the eco-indicator 99 as the environmental index. The intensified design, incorporating thermal coupling, presents the best results of the designs studied, with a total annual cost value of $13.9 million and 4.21 × 10⁹ environmental points per year. This represents an economic saving of $4.6 million per year and reduces environmental impact by 1.15 × 10⁹ points compared to the reference design, providing a sustainable alternative for purifying levulinic acid at a cost of $0.261 per kilogram.