Screening alternative chemical routes based on inherent chemical process properties data: Methyl methacrylate case study

Abstract

In 1988 a campaign called Responsible Care was initiated as a response to the adverse publicity of the Bhopal disaster. The initiative commits chemical industries to improve safety, health, and environmental (SHE) performance. Inherent safety concept can be incorporated at any stage of process lifecycle. However, the best results will only be achieved if it is implemented during the initial research and development (R&D) phase, when chemists and engineers are considering different choices of process alternatives, besides making fundamental and yet critical decisions such as type of raw materials and operating conditions to be used throughout the process. Process hazards assessment during conceptual stage is important since degree of freedom for making changes is still high and the associated cost is low. Besides inherent safety features can be adopted most effectively. Alternative process routes screening during the R&D stage involves the assessment of huge number of chemical routes - sometimes there can be up to hundreds of them. However, time and information available at this point are very limited; thus simple and swift approaches are highly in demand. This paper presents the methods for evaluating SHE performance of chemical processes based on inherent chemical and process properties. To ensure their practicality and applicability, the methods require data which is readily acquired from Material Safety Data Sheet (MSDS) and process reaction chemistry. The methods are applied on six methyl methacrylate (MMA) manufacturing routes. The results show that the isobutylene based route (i-C4) is the best process from inherent safety aspect and the ethylene via methyl propionate based route (C2/MP) is the best one from inherent health and environmental criteria. Finally, multi-criteria decision-making tool is applied to select a route with the optimised SHE benigness level. Based on the study, the C2/MP is regarded as the best route with the optimum performances in the SHE aspects. The case study analysis shows that the methods are capable of comparing different design concepts by their individual S, H, E criteria as well as the optimised SHE aspect altogether effectively.