Avaliação do ciclo de vida do processo de obtenção de acetonitrila a partir do propeno, amônia e bioetanol

Abstract

Acetonitrile (ACN) is a valuable co-product in producing acrylonitrile (AN), serving as a feedstock in the petrochemical, pharmaceutical, and fine chemical industries. Enhancing the economy and sustainability of this process requires identifying improvement opportunities. This study conducted a Life Cycle Assessment (LCA) to evaluate the environmental impacts of ACN production and purification of 1 kg of ACN. The cradle-to-gate assessment compared the conventional fossil-based industrial process with a novel bioethanol and green ammonia approach. Four production scenarios were examined, encompassing different combinations of propene, ammonia, bioethanol, and green ammonia. For comparison, four production scenarios were evaluated: (i) production of ACN at 85 %wt and (ii) at 99.9 %wt from propylene and fossil ammonia; (iii) production of ACN 99.9 %wt from propylene, bioethanol and fossil ammonia, and (iv) from propylene, bioethanol and green ammonia. The ReCiPe 2016 Midpoint method was applied, utilizing the Ecoinvent database available in the SIMAPRO® software to assess the environmental impacts categories such as global warming, land use, scarcity of fossil resources, human toxicity, ecotoxicity and water consumption. The scenario using bioethanol, propylene and green ammonia, produced with hydrogen from the electrolysis of water, showed an impact reduction of 5%. In addition, there was a 36% reduction in the categories of scarcity of fossil resources and global warming. The route using bioethanol and green ammonia was the most sustainable compared to the fossil-based process. However, the study revealed the need to use a national inventory for bioethanol. This study's LCA sheds light on the environmental implications of ACN production and purification. It demonstrates that alternative approaches, such as incorporating bioethanol and green ammonia, can reduce environmental impacts compared to the conventional fossil-based process. These findings underline the potential for improving the sustainability of ACN production in the petrochemical industry.