(349b) Simultaneous Model-Based Process and Product Design Using Reverse Design Approach

In order to meet the demands of specifically architectured fine chemicals it is mandatory to design the process and product simultaneously. In this work, we are mainly dealing with obtaining very specific products, which need hybrid processes for their production. These hybrid processes, involve integrated operations of two or more unit operations and offer opportunities for process improvements, which otherwise, would make the original processing route infeasible. For example, reaction schemes (processing routes) may be discarded early because of low product yield but addition of an on-site membrane-based separation to remove the products (or by-products) can significantly change the operability and economics of the process. In this case, the polymer-based membrane needs to be designed together with the hybrid process. The main objective of this paper is to present a systematic model based approach that is able to propose a candidate polymer that could be used for a membrane based separation where the desired separation targets are already defined. A trial-and-error procedure is usually employed where different candidate polymers are tested and this procedure is repeated until a polymer that matches the separation criteria is found. Apart from being computationally heavy due to the iterative scheme, it is mathematically a difficult problem to solve as the property models for the polymer to be tested needs to be embedded in the process models. An alternative an approach where one finds the polymer with that particular microscopic structure that optimally matches the target permeability (separation specifications) may be considered. The highlight of this work is simultaneous design of the membrane based separation process and of the polymeric membrane using the reverse design approach. This can be achieved by first defining the design targets in terms of the properties of the polymer for the specified separation task (step 1), and then finding (designing) polymers that match the property targets (step 2). In this way, the membrane process model does not need a polymer property model, since the properties are the unknown variables. Once the property targets are obtained from the first step, polymers corresponding to these properties can be found in mainly three ways: I. Making an extensive literature search to find out polymers that matches the targets; II. Finding out monomer units using group contribution methods; III. Finding out microscopic structural parameters (branch lengths, chain lengths, branch frequency etc.) using molecular simulations for various polymers. The application of the developed model-based methodology will be highlighted through case studies from the food industry (aroma purification) using different types of membrane-distillation; for gas separation where the design of polymeric membrane will be highlighted together with the design of hybrid separation scheme; and finally, the use of pervaporation/nanofiltration coupled to a batch reaction scheme for a pharmaceutical product to significantly increase the product yield will be highlighted.