Rotation dynamics of 2-methyl butane and n-pentane in MCM-22 zeolite: a molecular dynamics simulation study

Abstract

Molecular dynamics (MD) simulations have been performed to investigate the rotational diffusive motion for 2-methyl butane (2-MeC4) and n-pentane (n-C5) in the cages of MCM-22 zeolite from 200-340 K. The rotation intermediate scattering function I(R) (Q,t) for 2-MeC4 and n-C5 confined in the supercages of MCM-22 was calculated. The dynamic scattering functions S(inc)(Q,omega) obtained via Fourier transformation of this intermediate scattering function are in good agreement with those of quasi-elastic neutron scattering experiments. The rotational intermediate scattering functions of 2-MeC4 decay more rapidly than those of n-C5 before 1.0 ps. In the longer time region, the rotational intermediate scattering functions of both molecules intersect. It is shown that n-C5 molecules move more easily from supercage to supercage compared to 2-MeC4, rotating for a longer time in the confinement of the MCM-22 supercage.

Diffusion of Biomass Pyrolysis Products in H-ZSM-5 by Molecular Dynamics Simulations

“…The TraPPE force field, which has been shown to work well when simulating the adsorption and diffusivity of alcohol molecules in zeolites, − was used for the methanol, ethanol, and glycolaldehyde molecules. The OPLS force field, which has been applied to study the diffusion of alkanes − and cyclic hydrocarbons, − was used for the aromatic hydrocarbons.…”

Experiences with the publicly available multipurpose simulation code, Music

“…[26,30,52 -66] Other materials, such as calixarenes, polymers and mesoporous molecular sieves, and more exotic adsorbates, such as volatile organic compounds and explosives, have also been investigated. [67][68][69][70][71][72] As Music was written using object-oriented programming principles and following a set of rules outlined in the original paper, [13] changes and addition to the source code are (relatively) straightforward and users can adapt Music to suit their own needs. In our eyes, this is one of the most attractive features of the code, and the following paragraphs give a few examples from our own work that took advantage of this feature.…”