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Title: Adsorption and diffusion of fructose in zeolite HZSM-5: selection of models and methods for computational studies.

Abstract

The adsorption and protonation of fructose in HZSM-5 have been studied for the assessment of models for accurate reaction energy calculations and the evaluation of molecular diffusivity. The adsorption and protonation were calculated using 2T, 5T, and 46T clusters as well as a periodic model. The results indicate that the reaction thermodynamics cannot be predicted correctly using small cluster models, such as 2T or 5T, because these small cluster models fail to represent the electrostatic effect of a zeolite cage, which provides additional stabilization to the ion pair formed upon the protonation of fructose. Structural parameters optimized using the 46T cluster model agree well with those of the full periodic model; however, the calculated reaction energies are in significant error due to the poor account of dispersion effects by density functional theory. The dispersion effects contribute -30.5 kcal/mol to the binding energy of fructose in the zeolite pore based on periodic model calculations that include dispersion interactions. The protonation of the fructose ternary carbon hydroxyl group was calculated to be exothermic by 5.5 kcal/mol with a reaction barrier of 2.9 kcal/mol using the periodic model with dispersion effects. Our results suggest that the internal diffusion of fructose in HZSM-5 ismore » very likely to be energetically limited and only occurs at high temperature due to the large size of the molecule.« less

Authors:
; ; ; ; ;  [1];  [2];  [2];  [2]
  1. (Center for Nanoscale Materials)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1033857
Report Number(s):
ANL/MSD/JA-70941
Journal ID: ISSN 1932-7447; TRN: US1200617
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry C
Additional Journal Information:
Journal Volume: 115; Journal Issue: 44; Journal ID: ISSN 1932-7447
Country of Publication:
United States
Language:
ENGLISH
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ADSORPTION; BINDING ENERGY; CARBON; CLUSTER MODEL; DIFFUSION; ELECTROSTATICS; EVALUATION; FRUCTOSE; FUNCTIONALS; ION PAIRS; STABILIZATION; THERMODYNAMICS; ZEOLITES

Citation Formats

Cheng, L., Curtiss, L. A., Assary, R. S., Greeley, J., Kerber, T., Sauer, J., MSD), Northwestern Univ.), and Humboldt-Universitat zu Berlin). Adsorption and diffusion of fructose in zeolite HZSM-5: selection of models and methods for computational studies.. United States: N. p., 2011. Web. doi:10.1021/jp2062018.
Cheng, L., Curtiss, L. A., Assary, R. S., Greeley, J., Kerber, T., Sauer, J., MSD), Northwestern Univ.), & Humboldt-Universitat zu Berlin). Adsorption and diffusion of fructose in zeolite HZSM-5: selection of models and methods for computational studies.. United States. doi:10.1021/jp2062018.
Cheng, L., Curtiss, L. A., Assary, R. S., Greeley, J., Kerber, T., Sauer, J., MSD), Northwestern Univ.), and Humboldt-Universitat zu Berlin). Wed . "Adsorption and diffusion of fructose in zeolite HZSM-5: selection of models and methods for computational studies.". United States. doi:10.1021/jp2062018.
@article{osti_1033857,
title = {Adsorption and diffusion of fructose in zeolite HZSM-5: selection of models and methods for computational studies.},
author = {Cheng, L. and Curtiss, L. A. and Assary, R. S. and Greeley, J. and Kerber, T. and Sauer, J. and MSD) and Northwestern Univ.) and Humboldt-Universitat zu Berlin)},
abstractNote = {The adsorption and protonation of fructose in HZSM-5 have been studied for the assessment of models for accurate reaction energy calculations and the evaluation of molecular diffusivity. The adsorption and protonation were calculated using 2T, 5T, and 46T clusters as well as a periodic model. The results indicate that the reaction thermodynamics cannot be predicted correctly using small cluster models, such as 2T or 5T, because these small cluster models fail to represent the electrostatic effect of a zeolite cage, which provides additional stabilization to the ion pair formed upon the protonation of fructose. Structural parameters optimized using the 46T cluster model agree well with those of the full periodic model; however, the calculated reaction energies are in significant error due to the poor account of dispersion effects by density functional theory. The dispersion effects contribute -30.5 kcal/mol to the binding energy of fructose in the zeolite pore based on periodic model calculations that include dispersion interactions. The protonation of the fructose ternary carbon hydroxyl group was calculated to be exothermic by 5.5 kcal/mol with a reaction barrier of 2.9 kcal/mol using the periodic model with dispersion effects. Our results suggest that the internal diffusion of fructose in HZSM-5 is very likely to be energetically limited and only occurs at high temperature due to the large size of the molecule.},
doi = {10.1021/jp2062018},
journal = {Journal of Physical Chemistry C},
issn = {1932-7447},
number = 44,
volume = 115,
place = {United States},
year = {2011},
month = {9}
}