Kinetics modeling of ethylbenzene dehydrogenation to styrene over a mesoporous alumina supported iron catalyst

The kinetics of ethylbenzene (EB) dehydrogenation over a FeOx-meso-Al2O3 catalyst is studied. The models were developed based on physicochemical characterization and a CREC fluidized Riser Simulator data. N-2 adsorption shows that the synthesized FeOx-meso-Al2O3 catalyst is mesoporous with pore size between 9 and 35 nm. TPR profile indicates that iron on meso-Al2O3 forms easily reducible nanostructured crystals which is confirmed by TEM image. NH3- and CO-TPD analysis, respectively reveals the availability of both acidic and basic sites. The dehydrogenation of ethylbenzene on FeOx-meso-Al2O3 catalyst mainly gives styrene (similar to 99%) while a small amount of benzene, toluene and coke are also detected. Based on the experimental observations two Langmuir-Hinshelwood type kinetics models are formulated. The possible catalyst deactivation is expressed as function of EB conversion. Parameters are estimated by fitting of the experimental data implemented in MATLAB. Results show that one type site Langmuir-Hinshelwood model appropriately describes the experimental data, with adequate statistical fitting indicators and also satisfied the physical constraints. The activation energy for the formation of styrene (80 kJ/mol) found to be significantly lower than that of the undesired products benzene (144 kJ/mol) and toluene (164 kJ/mol). The estimated heat of adsorptions of EB and ST are found to be 55 kJ/mol and 19 kJ/mol, respectively. (c) 2012 Elsevier B.V. All rights reserved.