Sustainable Process Design Approach for On-Purpose Propylene Production and Intensification

The advent of shale gas and the increasing spread between the supply and demand curves for propylene present an opportunity for adopting alternative pathways to produce propylene. This study aims to investigate a sustainable process design approach to on-purpose propylene production. A hierarchical approach to sustainable process design is proposed and implemented in a case study with propane dehydrogenation as the process under consideration. A base case design was developed, and process integration and intensification techniques were applied to reduce dependence on external utilities and to lower the overall capital investment. Waste heat recovery and offgas recycle were additional options used to intensify the overall energy consumption of the process. Emissions from the process were calculated from the Environmental Protection Agency's guidelines. Economic and environmental metrics were then used to study the impact of integration and intensification techniques. Up to 70% reductions in CO2 emissions were achieved as a result of this approach to sustainable design. The Sustainability Weighted Return on Investment metric was evaluated for all cases. Multiobjective decision making for the optimum design was facilitated by the sustainability metrics augmented with the traditional economic criteria.