Optimal design of solvents for extractive reaction processes

Abstract

It is well known that solvents can have significant effects on rates and equilibrium compositions of chemical reactions. The computer‐aided molecular design (CAMD) of solvents for heterogeneous liquid phase reactions is challenging due to multiple solvent effects on reaction and phase equilibria. In this work, we propose a CAMD methodology based on a genetic algorithm (GA) for identifying optimal solvents for liquid phase reactions where the objective is to maximize the reaction equilibrium conversion. In particular, a novel molecular encoding method is introduced to facilitate the construction and evaluation of solvent molecules in a defined structure space. The reliability of the method for fast identification of optimal reaction solvents is demonstrated for a selected biphasic esterification reaction. The proposed approach opens up new perspectives for intensifying extractive reaction processes via the purposeful design of solvent molecules. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3238–3249, 2016

A hybrid stochastic–deterministic optimization approach for integrated solvent and process design

“…In order to apply the GA to molecular design, molecular structures must be expressed in a readable and operable form. In our previous work (Zhou et al, 2015c), an efficient molecular encoding method was proposed where molecules are represented as tree structures and encoded in the form of a dynamic list with UNIFAC groups as tree nodes. In the dynamic tree structure, each group node is a structural array with four fields (see Figure 1).…”

“…The first two fields provide group identity information including group ID number and group valence. The last two contain group connectivity information with "Size" denoting the number of group nodes in the sub-tree and "*Child It is worth noting that the proposed dynamic tree structure facilitates the handling of genetic operations and always guarantees structurally feasible molecules (Zhou et al, 2015c). Based on the molecular encoding method, a GA has been developed and used to design solvents for chemical reactions (for more information, please refer to Zhou et al, 2015c).…”

“…Select parent molecules from the current generation based on the roulette wheel selectionrule(Lipowski and Lipowska, 2012).6. Create offspring molecules for the next generation via genetic operations(Zhou et al, 2015c) performed on the selected parents. Repeat Step 3 and Step 4.7.The computation is terminated if predefined stopping criteria are satisfied (usually a maximum number of generations is specified).…”

Structure optimization of tailored ionic liquids and process simulation for shale gas separation

“…With the binary interaction parameters regressed from experimental data, the UNIFAC model has been found to give good quantitative prediction accuracy for specific gas‐IL systems. Moreover, as a group contribution‐based model, it is very useful for a quick and reliable solvent screening . Having the UNIFAC model available, the optimal IL for gas separation can be designed through a computer‐aided molecular design approach .…”

Integrated solvent and process design for continuous crystallization and solvent recycling using PC‐SAFT

“…Furthermore, the simultaneous optimization of solvent type and process conditions leads to a mixed‐integer nonlinear programming (MINLP) problem due to the discrete nature of solvent selection, which is notoriously difficult to solve. Therefore, solution strategies such as model simplification, decomposition‐based algorithms and stochastic algorithms are commonly used for integrated solvent and process design. A continuous mapping method has been applied successfully to solve the combined process and solvent optimization problem for CO 2 absorption .…”