Single-Event Kinetic Modeling of Olefin Cracking on ZSM-5: Proof of Feed Independence

One of the crucial advantages of single-event kinetic models is the possibility of extrapolating them to other reaction conditions, which is highly interesting for catalyst design. However, no publication exists that proves the theoretically derived feature of single-event parameters being applicable to different olefins as feed though derived from kinetic experiments with only one certain feed olefin. Therefore, this work provides evidence that a single-event kinetic model for 1-pentene cracking on ZSM-5 is able to reproduce experimental results from the literature with different olefins as feed as long as a consistent set of thermodynamic data is used. The model predicts product distributions from two different kinetic studies of olefin cracking on ZSM-5 with high accuracy at all temperatures (400-490 °C), at all feed partial pressures (47.6-131 mbar), for all olefins as reactant (C₃-C₇), and for both water-containing and water-free feeds. The calculations for arbitrary olefin mixtures as feed also show excellent agreement. Consequently, the model describes intrinsic kinetics of olefin interconversion. The underlying kinetic parameters are independent of reaction conditions, feed, and composition of ZSM-5 (powder or extrudate) and can be transferred to other systems without adjustment. Limitations in extrapolation emerge when the binder influences the product distribution to a significant extent, for example, by altering diffusion characteristics. Finally, reproduction of literature results is also performed as a function of contact time, which requires an implementation of water adsorption for one of the two studies. The analysis of evolutions over contact time reveal both a catalyst and a carbon number dependence of the protonation enthalpy with the latter being independent of investigated ZSM-5 type and thus also transferable.