Chemical kinetic modeling of i‐butane and n‐butane catalytic cracking reactions over HZSM‐5 zeolite

Abstract

A chemical kinetic model for i‐butane and n‐butane catalytic cracking over synthesized HZSM‐5 zeolite, with SiO2/Al2O3 = 484, and in a plug flow reactor under various operating conditions, has been developed. To estimate the kinetic parameters of catalytic cracking reactions of i‐butane and n‐butane, a lump kinetic model consisting of six reaction steps and five lumped components is proposed. This kinetic model is based on mechanistic aspects of catalytic cracking of paraffins into olefins. Furthermore, our model takes into account the effects of both protolytic and bimolecular mechanisms. The Levenberg–Marquardt algorithm was used to estimate kinetic parameters. Results from statistical F‐tests indicate that the kinetic models and the proposed model predictions are in satisfactory agreement with the experimental data obtained for both paraffin reactants. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2456–2465, 2012

Kinetic study of propane aromatization over Zn/HZSM-5 zeolite under conditions of catalyst deactivation using genetic algorithm

“…The obtained trends in Fig. 6 are similar to the results of Roohollahi et al 26 and Choudhary et al 37 Fig . S-1 of the Supplementary material shows that the higher contact time leads to the higher propane conversion at different temperatures and times on stream.…”

“…Recently, a lumped kinetic model has been developed to avoid such aforementioned problems. [25][26][27] The recent developments in genetic algorithms (GAs) have led to a renewed interest within the field of chemical engineering. It plays an important role considering the issues of optimization problems, such as the reactor design, 28 the optimization of reaction conditions 29 and the estimation of kinetic parameters.…”

“…To decrease the number of the reaction species, lumping all isomers of the same carbon number into a single component was carried out. [25][26][27] The main aim of this study is to develop a lumped kinetic model, by considering the reaction conditions and products distribution of propane aromatization.…”

“…The simple power law model is usually used due to the complexity of the catalytic reactions. In the previous studies, 26,27 the lumped kinetic model was used for the catalytic cracking assuming the first and second-order reactions. In order to improve the precision of the kinetic parameters, the power law model was applied to calculate the rate of each reaction step.…”

“…Since diameters ratio of the reactor and catalyst particles, d r /d p was in the range of 10-20 (particle fraction between 0.3 and 0.6 mm) and the ratio of the reactor length and catalyst particles diameter, L/d p was in the range of about 35-65 and also the temperature gradient along the fixed-bed was less than 1 °C, the isothermal plug flow reactor conditions can be considered. 16,26 Based on the aforementioned matters, the following expressions are determined:…”