GREEN CHEMISTRY AND ENGINEERING: Drivers, Metrics, and Reduction to Practice

Green chemistry and engineering is the design of chemical manufacturing systems to minimize their adverse affects on the environment. Thus, a primary goal of green chemistry and engineering is to reduce the environmental impact of chemical processes and chemical manufacturing while simultaneously enhancing the overall process performance. Although it is beneficial to simply reduce the use of organic solvents in chemical processes, green chemistry and engineering goes further, in that it evaluates the entire manufacturing operation to identify techniques that can be applied to minimize the overall process hazard, while maintaining economic practicality. Evaluation of the environmental impacts of the manufacturing process requires a systems approach and appropriate metrics that permit quantitative assessment of environmental hazards. Thus, this chapter begins with a discussion of the drivers for green engineering and the metrics through which processes can be evaluated. Then, the hydroformylation process is used as a case study to illustrate the way in which green chemistry principles can be applied to real processes. Two elements are specifically highlighted: (a) the use of catalysts to facilitate active and selective chemistry and the immobilization of said catalysts within the reactor system, and (b) the development of processes based on benign reaction solvents, and the benefits that can accrue from simplified separations operations.