Incorporating Sustainability into the Conceptual Design of Chemical Process-Reaction Routes Selection

Limited availability of natural resources and rising raw material cost, accompanied by growing societal and environmental concerns, urge the engineers to incorporate sustainability issues into the design of new chemical process and the retrofit of traditional process. Yet due to the multidimensional nature of sustainability, as economic, societal, and environmental issues need to be considered together, a structured sustainability assessment tool is needed to serve as the basis for any process design, analysis, improvement, and decision making. This paper presents a methodology to assist reaction pathway selection in light of sustainability. At this conceptual design stage, the sustainability performance of different potential reaction pathways is evaluated, which can not only help the designers improve the screening efficiency by eliminating inferior reaction alternatives systematically, but also identify the key areas for further improvement in future design, thus reducing the complexity and labor in the following basic engineering design stage. The sustainability of each reaction pathway is assessed in terms of profit potential, driving force of the pathway (Gibbs free energy), inherent safety index, potential environmental index, and atom economy. The efficacy of this approach is demonstrated by several case studies of reaction routes selection, including the propylene oxide (PO) production process, carbon dioxide reduction technology, and cellulosic ethanol production technology.