Production of n-propyl acetate by reactive distillation : experimental and theoretical study

First steps of the development of a catalytic reactive distillation process for the production of n-propyl acetate based on experiments and simulations are proposed. The kinetics for homogeneously (sulphuric acid) and heterogeneously (Amberlyst 15) catalysed reaction were investigated and the constants for a pseudo-homogeneous model are presented. Pilot plant experiments were performed using a homogeneous strong acid catalyst in a packed column. A top-column decanter is used to withdraw the aqueous phase and to reflux the organic phase. Simulation results are in good agreement with experimental data. Thermodynamics nonidealities are taken into account using VLE and LLE NRTL interaction parameters. Alcohol conversion and n-propyl acetate purity may be dramatically increased just by adding to the pilot plant a stripping section in an additional column: six different configurations are identified to achieve such a production. The startup is studied in order to determine the best strategy to achieve steady-state conditions. The strong influence of the composition of the initial charging in the decanter can be seen and an initial charging of the two-phase top product leads to the fastest startup

Rigorous Multicomponent Reactive Separations Modelling : Complete Consideration of Reaction-Diffusion Phenomena

This paper gives the first step of the development of a rigorous multicomponent reactive separation model. Such a model is highly essential to further the optimization of acid gases removal plants (CO2 capture, gas treating, etc.) in terms of size and energy consumption, since chemical solvents are conventionally used.Firstly, two main modelling approaches are presented: the equilibrium-based and the rate-based approaches. Secondly, an extended rate-based model with rigorous modelling methodology for diffusion-reaction phenomena is proposed. The film theory and the generalized Maxwell-Stefan equations are used in order to characterize multicomponent interactions. The complete chain of chemical reactions is taken into account. The reactions can be kinetically controlled or at chemical equilibrium, and they are considered for both liquid film and liquid bulk. Thirdly, the method of numerical resolution is described. Coupling the generalized Maxwell-Stefan equations with chemical equilibrium equations leads to a highly non-linear Differential-Algebraic Equations system known as DAE index 3. The set of equations is discretized with finite-differences as its integration by Gear method is complex. The resulting algebraic system is resolved by the Newton- Raphson method. Finally, the present model and the associated methods of numerical resolution are validated for the example of esterification of methanol. This archetype non-electrolytic system permits an interesting analysis of reaction impact on mass transfer, especially near the phase interface. The numerical resolution of the model by Newton-Raphson method gives good results in terms of calculation time and convergence. The simulations show that the impact of reactions at chemical equilibrium and that of kinetically controlled reactions with high kinetics on mass transfer is relatively similar. Moreover, the Fick’s law is less adapted for multicomponent mixtures where some abnormalities such as counter-diffusion take place

Weblab in Chemical Engineering between France and Brazil : validation of the methodology

A Weblab is an experiment operated remotely via internet. Besides the strictly technical aspects of such an experiment, which may contribute for the learning of Chemical Engineering fundamentals, there is another important feedback when teams of students of two different countries are working together: the Weblab turns into an intercultural experience, enhancing the communication skills of the students. A Weblab between Universidade Federal de São Carlos (DEQ/UFSCar) and the Ecole Nationale Supérieurs d’Ingénieurs en Arts Chimiques et Technologiques (ENSIACET) is presented in this work. A mass transfer experiment in a bench scale reactor (agitated and aerated) had to be studied by heterogeneous teams, thus emulating challenges that will be common in future work environments. In order to perform the experiment, students in Brazil and in France were gathered into groups. The students had to make decisions about the procedure to drive the experiments. All the students were able to control the equipment, no matter where they physically were. Students communicated using video conference software. The students and teachers opinions on this experience were very positive. This methodology is an important contribution to the formation of engineers in a world integrated by modern communication technologies

Étude de faisabilité de l’estérification d’un diacide par distillation réactive

Cette étude propose une approche systématique de la conception d’une colonne à distiller réactive. Elle a été appliquée avec succès au cas peu étudié des réactions consécutives. L’estérification de l’acide 2 methyl glutarique par le méthanol a été traitée. Les 3 premières étapes de la méthode montrent la faisabilité de la production dans une colonne hybride avec un taux de reflux faible et la nécessité de travailler avec un excès de méthanol. Ces résultats théoriques ont ensuite été consolidés par un pilotage sur une colonne de diamètre 75 mm. Dans tous les régimes pilotés, les résultats obtenus sont significativement supérieurs à un réacteur en lit fixe même avec des excès de réactif plus important