Modelling and constraint optimisation of an aromatic nitration in liquid–liquid medium

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 91; no. 1; pp. 75 - 84
• Main Authors: D’Angelo, Flavio Augusto, Brunet, Léna, Cognet, Patrick, Cabassud, Michel
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.2003; Elsevier
• Subjects: Applied sciences; Chemical engineering; Exact sciences and technology; Modelling; Optimisation; Reactors; Safety constraint; Semi-batch reactor; Toluene mononitration; Semi-batch reactor; Modelling; Safety constraint; Optimisation; Toluene mononitration; Nitration; Hydrocarbon; Exothermic reaction; Conversion rate; Liquid liquid reaction; Toluene; Theoretical study; Experimental study; Modeling; Nitric acid; Constrained optimization; Sulfuric acid; Kinetic model; Aromatic compound; Kinetics; Aqueous solution; Safety; Mathematical model; Reactor; Monocyclic compound; Semicontinuous; Heterogeneous reaction
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/S1385-8947(02)00139-0

A methodology, which determines the operating conditions simultaneously optimising the chemical yield and considering the safety aspect, has been developed for a chemical reaction which is carried out batch-wise. To illustrate the methodology, the aromatic nitration of toluene by mixed acid has been chosen as a typical exothermic and non-selective reaction. This reaction takes place in a two-phase medium and, therefore, involves simultaneously chemical reaction and mass transfer phenomena. A kinetic model recently proposed for the slow and fast liquid–liquid reaction regimes was integrated to the mass balance. Nitration experiments were carried out in order to compare experimental composition profiles with simulated ones. Afterwards, an optimisation procedure has been used to maximise conversion, by manipulating the operating conditions subject to safety constraints. The p-nitrotoluene yield was chosen as the criterion to be maximised. Experimental validation for the optimisation procedure has been carried out. A monofluid heating–cooling system controlled by a predictive controller was used for the temperature control of the reactor. Simulation and experimental results are presented, discussed and compared.