Simulating Microwave-Heated Diffusion in Zeolite Nanopores
Abstract:We have performed equilibrium molecular dynamics and microwave (MW) heated molecular dynamics simulations to explore how MW heating influences self-diffusion in zeolite nanopores. We have applied these simulations to methanol and/or benzene in de-aluminated Y zeolite. We have found that even under the non-equilibrium conditions of MW heating, center-of-mass motions can be associated with effective temperatures. However, we find that the temperatures controlling kinetic and potential energy distributions are not generally the same in MW-heated systems, with potential temperatures generally exceeding kinetic ones. This finding has a consequence for understanding MW-heated diffusion in zeolites. In particular, when temperatures are sufficiently high that diffusion is not strongly activated, MW-heated diffusivities are equal to equilibrium diffusivities at the same kinetic temperature. On the other hand, when diffusion becomes more strongly activated at lower temperatures, MW-heated diffusivities consistently exceed equilibrium diffusivities at the same kinetic temperature, because the MW-heated potential distributions enable more facile barrier crossing. This result shows that, in general, MW-heated diffusion is more complicated than simply "different components diffusing at different temperatures." Instead, we advocate the picture involving different components diffusing at different kinetic and potential temperatures.
Document Type: Research Article
Publication date: 2004-09-01
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- Journal of Computational and Theoretical Nanoscience is an international peer-reviewed journal with a wide-ranging coverage, consolidates research activities in all aspects of computational and theoretical nanoscience into a single reference source. This journal offers scientists and engineers peer-reviewed research papers in all aspects of computational and theoretical nanoscience and nanotechnology in chemistry, physics, materials science, engineering and biology to publish original full papers and timely state-of-the-art reviews and short communications encompassing the fundamental and applied research.
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