COMPUTER-AIDED MOLECULAR DESIGN - A NOVEL METHOD FOR OPTIMAL SOLVENT SELECTION

The task of selecting a solvent or solvent mixture with desirable comb ination of physical properties, to meet the needs of specific applicat ions, has largely been tackled using a combination of heuristics and c ostly experimental studies. This material selection problem is here fo rmulated as the combinatorial molecular design problem of choosing a s et of structural groups making up a target molecule with the desired p roperties as predicted by available group contribution techniques. A n ovel mixed-integer nonlinear programming (MINLP) technique is used to solve the problem yielding compounds with optimum value of an appropri ate performance index, subject to material balances, process and desig n limitations and feasibility of molecular structures. The strategy is applied with excellent results to solvent design examples for liquid- liquid extraction and multicomponent gas absorption using varying comb inations of objective functions and constraints to reflect directly a multiplicity of operational objectives.