Surface Interactions and Confinement of Methane: A High Pressure Magic Angle Spinning NMR and Computational Chemistry Study

Salim Ok, David W. Hoyt, Amity Andersen, Julie Sheets, Susan A. Welch, David R. Cole, Karl Todd Mueller, Nancy M. Washton

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Characterization and modeling of the molecular-level behavior of simple hydrocarbon gases, such as methane, in the presence of both nonporous and nanoporous mineral matrices allows for predictive understanding of mportant processes in engineered and natural systems. In this study, changes in local electromagnetic environments of the carbon atoms in methane under conditions of high pressure (up to 130 bar) and moderate temperature up to 346 K) were observed with 13C magic-angle spinning (MAS) NMR spectroscopy while the methane gas was mixed with two model solid substrates: a fumed nonporous, 12 nm particle size silica and a mesoporous silica with 200 nm particle size and 4 nm average pore diameter. Examination of the interactions between methane and the silica systems over temperatures and pressures that include the supercritical regime was allowed by a novel high pressure MAS sample containment system, which provided high resolution spectra collected under in situ conditions. For pure met ane, no significant thermal effects were found for the observed 13C chemical shifts at all pressures studied here (28.2, 32.6, 56.4, 65.1, 112.7, and 130.3 bar). However, the 13C chemical shifts of resonances arising from confined methane changed slightly with changes in temperature in mixtures with mesoporous silica. The chemical shift values of 13C nuclides in methane change measurably as a function of pressure both in the pure state and in mixtures with both silica atrices, with a more pronounced shift when meso-porous silica is present. Molecular-level simulations utilizing GCMC, MD, and DFT confirm qualitatively that the experimentally measured changes are attributed to interactions of methane with the hydroxylated silica surfaces as well as densification of methane within nanopores and on pore surfaces.

Original languageEnglish (US)
Pages (from-to)1359-1367
Number of pages9
JournalLangmuir
Volume33
Issue number6
DOIs
StatePublished - Feb 14 2017

Fingerprint

Computational chemistry
computational chemistry
Magic angle spinning
Methane
metal spinning
surface reactions
Silicon Dioxide
methane
Nuclear magnetic resonance
chemistry
Silica
nuclear magnetic resonance
silicon dioxide
Chemical shift
chemical equilibrium
Gases
Particle size
porosity
Nanopores
containment

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

Ok, S., Hoyt, D. W., Andersen, A., Sheets, J., Welch, S. A., Cole, D. R., ... Washton, N. M. (2017). Surface Interactions and Confinement of Methane: A High Pressure Magic Angle Spinning NMR and Computational Chemistry Study. Langmuir, 33(6), 1359-1367. https://doi.org/10.1021/acs.langmuir.6b03590
Ok, Salim ; Hoyt, David W. ; Andersen, Amity ; Sheets, Julie ; Welch, Susan A. ; Cole, David R. ; Mueller, Karl Todd ; Washton, Nancy M. / Surface Interactions and Confinement of Methane : A High Pressure Magic Angle Spinning NMR and Computational Chemistry Study. In: Langmuir. 2017 ; Vol. 33, No. 6. pp. 1359-1367.
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Ok, S, Hoyt, DW, Andersen, A, Sheets, J, Welch, SA, Cole, DR, Mueller, KT & Washton, NM 2017, 'Surface Interactions and Confinement of Methane: A High Pressure Magic Angle Spinning NMR and Computational Chemistry Study', Langmuir, vol. 33, no. 6, pp. 1359-1367. https://doi.org/10.1021/acs.langmuir.6b03590

Surface Interactions and Confinement of Methane : A High Pressure Magic Angle Spinning NMR and Computational Chemistry Study. / Ok, Salim; Hoyt, David W.; Andersen, Amity; Sheets, Julie; Welch, Susan A.; Cole, David R.; Mueller, Karl Todd; Washton, Nancy M.

In: Langmuir, Vol. 33, No. 6, 14.02.2017, p. 1359-1367.

Research output: Contribution to journalArticle

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T2 - A High Pressure Magic Angle Spinning NMR and Computational Chemistry Study

AU - Ok, Salim

AU - Hoyt, David W.

AU - Andersen, Amity

AU - Sheets, Julie

AU - Welch, Susan A.

AU - Cole, David R.

AU - Mueller, Karl Todd

AU - Washton, Nancy M.

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