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Title: First-principles theoretical assessment of catalysis by confinement: NO–O 2 reactions within voids of molecular dimensions in siliceous crystalline frameworks

Abstract

Density functional theory methods that include dispersive forces are used to show how voids of molecular dimensions enhance reaction rates by the mere confinement of transition states analogous to those involved in homogeneous routes and without requiring specific binding sites or structural defects within confining voids. These van der Waals interactions account for the observed large rate enhancements for NO oxidation in the presence of purely siliceous crystalline frameworks. The minimum free energy paths for NO oxidation within chabazite (CHA) and silicalite (SIL) frameworks involve intermediates similar in stoichiometry, geometry, and kinetic relevance to those involved in the homogeneous route. The termolecular transition state for the kinetically-relevant cis-NOO 2NO isomerization to trans-NOO 2NO is strongly stabilized by confinement within CHA (by 36.3 kJ mol -1 in enthalpy) and SIL (by 39.2 kJ mol -1); such enthalpic stabilization is compensated, in part, by concomitant entropy losses brought forth by confinement (CHA: 44.9; SIL: 45.3, J mol -1 K -1 at 298 K). These enthalpy and entropy changes upon confinement agree well with those measured and combine to significantly decrease activation free energies and are consistent with the rate enhancements that become larger as temperature decreases because of the more negative apparentmore » activation energies in confined systems compared with homogeneous routes. Calculated free energies of confinement are in quantitative agreement with measured rate enhancements and with their temperature sensitivity. Such quantitative agreements reflect preeminent effects of geometry in determining the van der Waals contributions from contacts between the transition states (TS) and the confining walls and the weak effects of the level of theory on TS geometries. NO oxidation reactions are chosen here to illustrate these remarkable effects of confinement because detailed kinetic analysis of rate data are available, but also because of their critical role in the treatment of combustion effluents and in the synthesis of nitric acid and nitrates. Similar effects are evident from rate enhancements by confinement observed for Diels–Alder and alkyne oligomerization reactions. These reactions also occur in gaseous media at near ambient temperatures, for which enthalpic stabilization upon confinement of their homogeneous transition states becomes the preeminent component of activation free energies.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. Polytechnic Univ. of Milan (Italy). Dept. of Energy. Lab. of Catalysis and Catalytic Processes
  2. Univ. of California, Berkeley, CA (United States). Dept. of Chemical and Biomolecular Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Polytechnic Univ. of Milan (Italy)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); European Research Council (ERC)
OSTI Identifier:
1439777
Alternate Identifier(s):
OSTI ID: 1494078
Grant/Contract Number:  
AC02-05CH11231; 677423
Resource Type:
Published Article
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 20; Journal Issue: 23; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Maestri, Matteo, and Iglesia, Enrique. First-principles theoretical assessment of catalysis by confinement: NO–O2 reactions within voids of molecular dimensions in siliceous crystalline frameworks. United States: N. p., 2018. Web. doi:10.1039/c8cp01615a.
Maestri, Matteo, & Iglesia, Enrique. First-principles theoretical assessment of catalysis by confinement: NO–O2 reactions within voids of molecular dimensions in siliceous crystalline frameworks. United States. doi:10.1039/c8cp01615a.
Maestri, Matteo, and Iglesia, Enrique. Fri . "First-principles theoretical assessment of catalysis by confinement: NO–O2 reactions within voids of molecular dimensions in siliceous crystalline frameworks". United States. doi:10.1039/c8cp01615a.
@article{osti_1439777,
title = {First-principles theoretical assessment of catalysis by confinement: NO–O2 reactions within voids of molecular dimensions in siliceous crystalline frameworks},
author = {Maestri, Matteo and Iglesia, Enrique},
abstractNote = {Density functional theory methods that include dispersive forces are used to show how voids of molecular dimensions enhance reaction rates by the mere confinement of transition states analogous to those involved in homogeneous routes and without requiring specific binding sites or structural defects within confining voids. These van der Waals interactions account for the observed large rate enhancements for NO oxidation in the presence of purely siliceous crystalline frameworks. The minimum free energy paths for NO oxidation within chabazite (CHA) and silicalite (SIL) frameworks involve intermediates similar in stoichiometry, geometry, and kinetic relevance to those involved in the homogeneous route. The termolecular transition state for the kinetically-relevant cis-NOO2NO isomerization to trans-NOO2NO is strongly stabilized by confinement within CHA (by 36.3 kJ mol-1 in enthalpy) and SIL (by 39.2 kJ mol-1); such enthalpic stabilization is compensated, in part, by concomitant entropy losses brought forth by confinement (CHA: 44.9; SIL: 45.3, J mol-1 K-1 at 298 K). These enthalpy and entropy changes upon confinement agree well with those measured and combine to significantly decrease activation free energies and are consistent with the rate enhancements that become larger as temperature decreases because of the more negative apparent activation energies in confined systems compared with homogeneous routes. Calculated free energies of confinement are in quantitative agreement with measured rate enhancements and with their temperature sensitivity. Such quantitative agreements reflect preeminent effects of geometry in determining the van der Waals contributions from contacts between the transition states (TS) and the confining walls and the weak effects of the level of theory on TS geometries. NO oxidation reactions are chosen here to illustrate these remarkable effects of confinement because detailed kinetic analysis of rate data are available, but also because of their critical role in the treatment of combustion effluents and in the synthesis of nitric acid and nitrates. Similar effects are evident from rate enhancements by confinement observed for Diels–Alder and alkyne oligomerization reactions. These reactions also occur in gaseous media at near ambient temperatures, for which enthalpic stabilization upon confinement of their homogeneous transition states becomes the preeminent component of activation free energies.},
doi = {10.1039/c8cp01615a},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
number = 23,
volume = 20,
place = {United States},
year = {2018},
month = {6}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1039/c8cp01615a

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Cited by: 3 works
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Works referenced in this record:

Generalized Gradient Approximation Made Simple
journal, October 1996

  • Perdew, John P.; Burke, Kieron; Ernzerhof, Matthias
  • Physical Review Letters, Vol. 77, Issue 18, p. 3865-3868
  • DOI: 10.1103/PhysRevLett.77.3865

A climbing image nudged elastic band method for finding saddle points and minimum energy paths
journal, December 2000

  • Henkelman, Graeme; Uberuaga, Blas P.; Jónsson, Hannes
  • The Journal of Chemical Physics, Vol. 113, Issue 22, p. 9901-9904
  • DOI: 10.1063/1.1329672

Semiempirical GGA-type density functional constructed with a long-range dispersion correction
journal, January 2006

  • Grimme, Stefan
  • Journal of Computational Chemistry, Vol. 27, Issue 15, p. 1787-1799
  • DOI: 10.1002/jcc.20495