A Periodic DFT Study of Intramolecular Isomerization Reactions of Toluene and Xylenes Catalyzed by Acidic Mordenite

Abstract

A periodic density functional theory (DFT) study of the isomerization reactions of toluene and xylene catalyzed by acidic mordenite is reported. Monomolecular isomerization reactions have been considered and analyzed. The different reaction pathways have been discussed in detail. The use of periodic structure calculations allows consideration and analysis of zeolite electrostatic contributions and steric constraints that occur within zeolite micropores. Major differences in the details of protonation reaction pathways are found when periodic structures are used rather than small cluster models of the Brønsted acidic site. Complex relationships are found between zeolite topology and reaction pathways.

Plasmonic materials based on ZnO films and their potential for developing broadband middle-infrared absorbers

“…Then the nudge-elastic band (NEB) method was used to find the transition state connecting these two configurations. 45 The energy barriers for PGA intermediate decomposition at different stresses are listed in Table III, and the corresponding rate constants at 300 K can be calculated by the simple transition state theory. 46 The rate constant equation is shown as follows: where k B is the Boltzmann constant, T is the temperature, E is the energy barrier, q ‡ vib is the transition state molecular partition function q vib,R is the reactant molecules partition function, and υ k is the vibration frequency.…”

Hydrogen adsorption on M-ZSM-12 zeolite clusters (M = K, Na and Li): a density functional theory study

“…For instance, the distances of adsorbed geometries (C-O and Fe-C) for the two types of calculations were similarly calculated to be 1.142, 1.811 and 1.159, 1.778 Å , respectively [28]. It should be remarkably noted that theoretical calculations based on DFT where the periodic or cluster zeolite models are utilized generally give very parallel trends for reactivity [28][29][30][31]. Accordingly, in this study a cluster modeling method (relatively a larger cluster) was utilized to simulate extra framework metal species of ZSM-12 zeolite.…”

Zeolite-catalyzed Isomerization of 1-Hexene to trans-2-Hexene: An ONIOM Study

“…33,35 Hybrid methods, especially, the Our-own-N-layered Integrated molecular Orbital + molecular Mechanics (ONIOM) methods, 36,37 were found to be appropriate in describing the acidic site of the zeolite surface and yielding reasonable estimates of the system energetics, yet they are capable of reasonable simplification for the computation of the complex zeolite-guest molecule system in which numerical and computation capacities are highly demanding. On account of the above consideration, in this work we constructed a 54T cluster model to represent the local structures of H-ZSM-5 zeolite, with the effects of the zeolite framework being implicitly included in subsequent calculations (see Fig.…”