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PP-II-45OPTIMIZATION METHODS FOR A SEQUENCEOF EXHAUST GAS CONVERTERSŠtěpánek J. 1 , Kočí P. 1 , Kubíček M. 2 , Plát F. 1 , Marek M. 11 Dept. of Chemical Engineering, 2 Dept. of Mathematics, Institute of ChemicalTechnology, Prague. E-mail: jan.stepanek@vscht.czThe exhaust gas emission limits of internal combustion engines (used widely intransportation and power generation) are continuously being tightened. Particularlyfor lean-burn engines the exhaust gases need to be treated by a catalytic system(consisting of various monolithic reactor types, e.g. oxidation catalyst, NOx storageand reduction converter, and converter for selective catalytic reduction) [1, 2].The mathematical model of a catalytic converter is formed by a system of partialdifferential equations describing mass and enthalpy balances including mass andheat transport and reaction rate expressions. The partial differential equations aresolved by a finite difference method with (semi-)implicit difference approximation [3].This paper describes the use methods of mathematical optimization to find optimalparameters of each reactor in a cascade with respect to individual componentsconversions (CO, HC, NOx) while considering given restrictions (e.g., total systemvolume, maximum emissions allowed). The solution of this multi-criterional problemleads to Pareto sets. Pareto sets are such sets of solutions, where (in order tomaintain optimality) one criterion must be sacrificed when another one improves.Pontryagin's maximum principle may be used for finding the optimal operationconditions, e.g. minimization of additive consumption for selective catalytic reductionof NOx while maintaining high NOx conversion.References[1]. Güthenke A., Chatterjee D., Weibel M., Krutzsch B., Kočí P., Marek M., Nova I., Tronconi E.Current status of modeling lean exhaust gas aftertreatment catalysts. Adv. Chem. Eng. 2007, 33,103-211.[2]. Schejbal M., Marek M., Kubíček M., Kočí P. Modelling of diesel filters for particulatesremoval.Chem. Eng. J. 2009, 154, 219-230.[3]. Štěpánek J., Kočí P., Plát F., Kubíček M., Marek M. Investigation of combined DOC and NSRCdiesel car exhaust catalysts. Comp. Chem. Eng. 2010, In press,doi:10.1016/j.compchemeng.2010.01.003.AcknowledgementsThis work has been supported by the Czech ministry of education (ProjectMSM6046137306), the Czech grant agency (project 104/08/H055 and 104/08/1162) and theInstitute of Chemical Technology, Prague.416