Microkinetic Model of Propylene Oligomerization on Brønsted Acidic Zeolites at Low Conversion

The construction of a computational framework that describes the kinetic details of the propylene oligomerization reaction network on Brønsted acidic zeolites is particularly challenging due to the considerable number of species and reaction steps involved in the mechanism. This work presents a detailed microkinetic model at the level of elementary steps that includes 4243 reactions and 909 ionic and molecular species within the C2–C9 carbon number range. An automated generation procedure using a set of eight reaction families was applied to construct the reaction network. The kinetic parameters for each elementary step were estimated using transition state theory, Evans–Polanyi relationships, and thermodynamic data. The reaction mechanism and its governing kinetic parameters were embedded into the design equation of a plug-flow reactor, which was the reactor configuration used to experimentally measure reactant and product concentrations as a function of propylene conversion and temperature on a representative H-ZSM-5 (MFI) zeolite. The resulting mechanistic model is able to accurately describe the experimental data over a wide range of operating conditions in the low propylene conversion (<4%) regime. The agreement between experimentally measured propylene conversion and product selectivities and the model results demonstrates the robustness of the model and the approach used to develop it to simulate the kinetic behavior of this complex reaction network.