LCA case study: comparison between independent and coproduction pathways for the production of ethyl and n-butyl acetates

Abstract

Purpose The production of ethyl acetate and n-butyl acetate was investigated through two different pathways: either by independent reactions or by coproduction. In the coproduction pathway, the n-butyl acetate was produced by reusing the by-products of the synthesis of ethyl acetate. This study provides a comparison of the environmental impacts of these two pathways using a life cycle assessment (LCA). A discussion about the use of LCA on chemicals and its challenges was also developed. Methods Ethyl acetate and n-butyl acetate were synthesized with maximum respect to the principles of green chemistry (use of heterogeneous catalyst, energy savings, minimum steps). An innovative pathway was developed to avoid waste production, by reusing all the by-products of syntheses. After characterizing the feasibility of using these solvents in paint formulations, their potential impacts on the environment were evaluated through a cradle to gate analysis, up to the synthesis at laboratory scale. Most of the foreground data were directly collected with experimental trials. The background data that were not available in the Ecoinvent 3.1 database were estimated thanks to literature or proxys. Evaluations were then performed on the SimaPro 8.1.1 LCA software, using a derivative of ILCD 2011 1.05 as life cycle impact assessment methodology. Results and discussion The coproduction of both acetates led to the synthesis of purified ethyl acetate (purity of 92.1% w/w) and n-butyl acetate (purity of 97.1% w/w), after distillation. These results were quite similar to those obtained when independent syntheses were carried out. On an environmental point of view, it was found that the reagents preparation was always the step of the process responsible of the majority of the environmental impacts. The comparison between independent syntheses and coproduction showed that recycling the acetic acid produced during the first esterification (ethyl acetate from ethanol and acetic anhydride) led to a decrease of the impacts from 5 to 23% for all the impact categories. Conclusions This innovative coproduction of ethyl and n-butyl acetates led to interesting results from both a technical and environmental perspective, with a clear reduction of the environmental impacts. In a context of sustainable chemistry, this appears to be a very interesting way of production. Concerning the LCA of chemicals, a lot of work is still needed in order to improve the accuracy and the reliability of the assessment.

A Novel Process Using Ion Exchange Resins for the Coproduction of Ethyl and Butyl Acetates

“…As these green metrics do not show the environmental contribution of the whole process and in particular they do not take into account any energy consumption, the life cycle assessments of both pathways of production of ethyl and butyl acetates (Sc.1: individual syntheses and Sc.2: the co-production) have been compared [59]. The LCA analyses have shown that the co-production process generates lesser impacts on the environment than the individual syntheses of ethyl and butyl acetates ( Figure 11).…”

Production of n-Butyl Acetate through Continuous Reactive Distillation Using PTSA–POM as the Catalyst: Lab-Scale Experiments, Modeling and Validation, Commercial-Scale Design, and Economic Evaluation

“…It is also used as an extracting agent in pharmaceuticals. Commonly used methods for the production of n -butyl acetate are the esterification of acetic acid with n -butanol − and trans-esterification of methyl- or ethyl-acetate with n -butanol. − Researchers have also studied the coproduction of ethyl acetate and butyl acetate. − Among these, the most practiced method is liquid-phase esterification of acetic acid with n -butanol in the presence of an acid catalyst. This reaction is reversible and exothermic.…”