High Throughput Experimentation and Modeling as Tools for the Development of Green Alkylation Catalysts
Advancing the chemical engineering fundamentals
Catalysis - I (T2-13a)
Keywords: modeling, alkylation, zeolite, high throughput
The general trend in industrial Friedel-Crafts reactions is to move towards greener chemistry and cleaner production. One of the alternatives to the traditional polluting Friedel-Crafts catalysts are zeolites. When a chemical reaction is performed on zeolites instead of in the homogeneous liquid phase, the entire process becomes more complex, as besides the chemical reaction itself, other processes also play a role. In the case of zeolites, it is well known that deactivation by products often occurs, mainly influenced by how the several components interact and adsorb in the zeolite pores. Strong adsorption of some of the reactants or products often negatively influences the efficiency of the chemical reaction. In this study, a method is presented to extract critical information to understand what happens inside the zeolite packed reactor. As an example, the alkylation of bromobenzene with allyl acetate is performed on a high throughput continuous flow parallel reactor setup with a frontal analysis technique. During the transient operation of reaction and deactibvation, samples are collected and analyzed automatically. A detailed kinetic model was derived incorporating the main alkylation products (allylbromobenzene, cis- and trans-propenyl bromobenzene, each present in 3 isomeric forms and di-alkylated products), the side products (acetic acid and 1,2-propanediol diacetate) and the polymers causing deactivation. The model obviously includes equations describing the deactivation and the adsorption equilibria inside the zeolite pores. Independent adsorption experiments are performed to complete the information fed to the model. The Athena software package was used to solve the set of equations. Model discrimination was performed between several possible reaction mechanisms, including several deactivation mechanisms. In this way, the model is able to simultaneously predict the catalytic activity, the adsorption effects and clarify the process of deactivation. Such model can then be used for the selection of the best zeolite catalyst, and to derive the optimal operation conditions.
Presented Thursday 20, 09:45 to 10:05, in session Catalysis - I (T2-13a).
