LCA for Green Chemical Synthesis—Terephthalic Acid

Abstract

Researchers at the University of Kansas Center for Environmentally Beneficial Catalysis recently reported a one-step spray process concept as a greener alternative to the conventional Mid-Century process to produce high-purity terephthalic acid (TPA) (<25ppm 4-carboxybenzaldehyde). In the spray process, the enhanced gas–liquid mass transfer rates help to avoid oxygen starvation in the liquid phase, thereby facilitating the formation of polymer-grade TPA without the need for the subsequent hydrogenation step used in conventional processing. This provides not only significant economic benefit but also potential environmental benefits as revealed by comparative life-cycle assessments (LCAs). The environmental benefits are derived mainly from the avoidance of hydrogen production and the energy required for hydrogenation step for crude TPA purification in the conventional process, resulting in an approximately 57% reduction in greenhouse gas emissions. The results of the LCA analysis provide valuable guidance for the rational design and optimization of the spray process.