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Tian Z, Jiang P, Xu R. NMR Relaxation of Gas Adsorbed in Microporous Material. J Phys Chem Lett 2024; 15:3023-3028. [PMID: 38465889 DOI: 10.1021/acs.jpclett.4c00221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
NMR relaxometry has been widely applied to characterize fluid confined in porous media because of its versatility, chemical selectivity, and noninvasive nature. Here we extend its usage to gas adsorbed in microporous materials by establishing a new quantitative model based on the molecular level NMR relaxation mechanism revealed by the molecular simulation of a prototypical adsorption system, CH4 adsorbed in ZIF-8. The model enables new NMR relaxometry-based characterization methods for thermodynamic, dynamic, and structural properties of adsorption systems, as demonstrated and validated by the experiments where the adsorption capacity and self-diffusivity of H2, CH4, and small alcohols adsorbed in ZIF-8 are deduced from the NMR relaxation data. The findings can serve for a better understanding of the composition-structure-properties relationships of a wide range of adsorption systems which is essential for the development and application of new functional microporous materials.
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Affiliation(s)
- Zijian Tian
- Key Laboratory for CO2 Utilization and Reduction Technology of Beijing, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Peixue Jiang
- Key Laboratory for CO2 Utilization and Reduction Technology of Beijing, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Ruina Xu
- Key Laboratory for CO2 Utilization and Reduction Technology of Beijing, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
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Pinheiro Dos Santos TJ, Orcan-Ekmekci B, Chapman WG, Singer PM, Asthagiri DN. Theory and modeling of molecular modes in the NMR relaxation of fluids. J Chem Phys 2024; 160:064108. [PMID: 38341792 DOI: 10.1063/5.0180040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 01/18/2024] [Indexed: 02/13/2024] Open
Abstract
Traditional theories of the nuclear magnetic resonance (NMR) autocorrelation function for intra-molecular dipole pairs assume a single-exponential decay, yet the calculated autocorrelation of realistic systems displays a rich, multi-exponential behavior, resulting in anomalous NMR relaxation dispersion (i.e., frequency dependence). We develop an approach to model and interpret the multi-exponential intra-molecular autocorrelation using simple, physical models within a rigorous statistical mechanical development that encompasses both rotational diffusion and translational diffusion in the same framework. We recast the problem of evaluating the autocorrelation in terms of averaging over a diffusion propagator whose evolution is described by a Fokker-Planck equation. The time-independent part admits an eigenfunction expansion, allowing us to write the propagator as a sum over modes. Each mode has a spatial part that depends on the specified eigenfunction and a temporal part that depends on the corresponding eigenvalue (i.e., correlation time) with a simple, exponential decay. The spatial part is a probability distribution of the dipole pair, analogous to the stationary states of a quantum harmonic oscillator. Drawing inspiration from the idea of inherent structures in liquids, we interpret each of the spatial contributions as a specific molecular mode. These modes can be used to model and predict the NMR dipole-dipole relaxation dispersion of fluids by incorporating phenomena on the molecular level. We validate our statistical mechanical description of the distribution in molecular modes with molecular dynamics simulations interpreted without any relaxation models or adjustable parameters: the most important poles in the Padé-Laplace transform of the simulated autocorrelation agree with the eigenvalues predicted by the theory.
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Affiliation(s)
| | | | - Walter G Chapman
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
| | - Philip M Singer
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
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Valiya Parambathu A, Chapman WG, Hirasaki GJ, Asthagiri D, Singer PM. Effect of Nanoconfinement on NMR Relaxation of Heptane in Kerogen from Molecular Simulations and Measurements. J Phys Chem Lett 2023; 14:1059-1065. [PMID: 36693239 DOI: 10.1021/acs.jpclett.2c03699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Kerogen-rich shale reservoirs will play a key role during the energy transition, yet the effects of nanoconfinement on the NMR relaxation of hydrocarbons in kerogen are poorly understood. We use atomistic MD simulations to investigate the effects of nanoconfinement on the 1H NMR relaxation times T1 and T2 of heptane in kerogen. In the case of T1, we discover the important role of confinement in reducing T1 by ∼3 orders of magnitude from that of bulk heptane, in agreement with measurements of heptane dissolved in kerogen from the Kimmeridge Shale, without any models or free parameters. In the case of T2, we discover that confinement breaks spatial isotropy and gives rise to residual dipolar coupling which reduces T2 by ∼5 orders of magnitude from the value for bulk heptane. We use the simulated T2 to calibrate the surface relaxivity and thence predict the pore-size distribution of the organic nanopores in kerogen, without additional experimental data.
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Affiliation(s)
- Arjun Valiya Parambathu
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas77005, United States
- Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Newark, Delaware19716, United States
| | - Walter G Chapman
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas77005, United States
| | - George J Hirasaki
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas77005, United States
| | - Dilipkumar Asthagiri
- Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee37830-6012, United States
| | - Philip M Singer
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas77005, United States
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Amaro-Estrada JI, Wang Y, Torres-Verdín C. Quantifying the Effect of Spatial Confinement on the Diffusion and Nuclear Magnetic Resonance Relaxation of Water/Hydrocarbon Mixtures: A Molecular Dynamics Simulation Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14540-14549. [PMID: 36399119 DOI: 10.1021/acs.langmuir.2c01357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We implement molecular dynamics (MD) simulations to explore the relaxation mechanisms involved in the description of translational diffusion and rotational dynamics in water/hydrocarbon interfaces. The analysis of density profiles, self-diffusion coefficients, and nuclear magnetic resonance (NMR) relaxation properties as a function of the confinement layer width and type of hydrocarbons improves the understanding of confined water properties at water/oil interfaces. Density profile fluctuations reveal the presence of water-oil interactions close to the interface. MD results show that self-diffusion coefficients and NMR relaxation times of planar and cylindrical water/oil interfaces are strongly influenced by layer thickness and geometry. Shorter (between 20 and 60%) self-diffusion coefficients and 1H NMR relaxation times were obtained for water/n-pentane, water/n-decane, and water/n-hexadecane systems than bulk diffusion coefficients. An increase in Larmor frequency from 2.3 MHz to 400 MHz shows that longitudinal relaxation time (T1) of confined oil has slightly larger differences at higher frequencies than the transverse relaxation time (T2). At 400 MHz, n-alkanes (n-pentane, n-decane, and n-hexadecane) exhibit longer relaxation times than at smaller frequency values (2.3 and 22 MHz). Analysis of spin-spin and spin-lattice times provides relevant information about inter- and intramolecular relaxation mechanisms of water and oil as a function of geometry and width of the interface layer. These MD results suggest that the strength of confinement and geometry play a vital role in the diffusion and NMR relaxation properties of water/oil interfaces.
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Affiliation(s)
- Jorge Ivan Amaro-Estrada
- Hildebrand Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, Austin, Texas78712, United States
| | - You Wang
- Hildebrand Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, Austin, Texas78712, United States
| | - Carlos Torres-Verdín
- Hildebrand Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, Austin, Texas78712, United States
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Singer PM, Valiya Parambathu A, Wang X, Asthagiri D, Chapman WG, Hirasaki GJ, Fleury M, Ranguelova K. Correction to "Elucidating the 1H NMR Relaxation Mechanism in Polydisperse Polymers and Bitumen Using Measurements, MD Simulations, and Models". J Phys Chem B 2021; 125:11338-11339. [PMID: 34609864 DOI: 10.1021/acs.jpcb.1c07950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Singer PM, Parambathu AV, Pinheiro Dos Santos TJ, Liu Y, Alemany LB, Hirasaki GJ, Chapman WG, Asthagiri D. Predicting 1H NMR relaxation in Gd 3+-aqua using molecular dynamics simulations. Phys Chem Chem Phys 2021; 23:20974-20984. [PMID: 34518855 DOI: 10.1039/d1cp03356e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Atomistic molecular dynamics simulations are used to predict 1H NMR T1 relaxation of water from paramagnetic Gd3+ ions in solution at 25 °C. Simulations of the T1 relaxivity dispersion function r1 computed from the Gd3+-1H dipole-dipole autocorrelation function agree within ≃8% of measurements in the range f0 ≃ 5 ↔ 500 MHz, without any adjustable parameters in the interpretation of the simulations, and without any relaxation models. The simulation results are discussed in the context of the Solomon-Bloembergen-Morgan inner-sphere relaxation model, and the Hwang-Freed outer-sphere relaxation model. Below f0 ≲ 5 MHz, the simulation overestimates r1 compared to measurements, which is used to estimate the zero-field electron-spin relaxation time. The simulations show potential for predicting r1 at high frequencies in chelated Gd3+ contrast-agents used for clinical MRI.
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Affiliation(s)
- Philip M Singer
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA.
| | - Arjun Valiya Parambathu
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA.
| | | | - Yunke Liu
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA.
| | - Lawrence B Alemany
- Shared Equipment Authority and Department of Chemistry, Rice University, 6100 Main St., Houston, TX 77005, USA
| | - George J Hirasaki
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA.
| | - Walter G Chapman
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA.
| | - Dilip Asthagiri
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA.
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Madhavi WM, Weerasinghe S, Momot KI. Reorientational dynamics of molecules in liquid methane: A molecular dynamics simulation study. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Asthagiri D, Chapman WG, Hirasaki GJ, Singer PM. NMR 1H- 1H Dipole Relaxation in Fluids: Relaxation of Individual 1H- 1H Pairs versus Relaxation of Molecular Modes. J Phys Chem B 2020; 124:10802-10810. [PMID: 33185099 DOI: 10.1021/acs.jpcb.0c08078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The intramolecular 1H NMR dipole-dipole relaxation of molecular fluids has traditionally been interpreted within the Bloembergen-Purcell-Pound (BPP) theory of NMR intramolecular relaxation. The BPP theory draws upon Debye's theory for describing the rotational diffusion of the 1H-1H pair and predicts a monoexponential decay of the 1H-1H dipole-dipole autocorrelation function between distinct spin pairs. Using molecular dynamics (MD) simulations, we show that for both n-heptane and water this is not the case. In particular, the autocorrelation function of individual 1H-1H intramolecular pairs itself evinces a rich stretched-exponential behavior, implying a distribution in rotational correlation times. However, for the high-symmetry molecule neopentane, the individual 1H-1H intramolecular pairs do conform to the BPP description, suggesting an important role of molecular symmetry in aiding agreement with the BPP model. The intermolecular autocorrelation functions for n-heptane, water, and neopentane also do not admit a monoexponential behavior of individual 1H-1H intermolecular pairs at distinct initial separations. We suggest expanding the autocorrelation function in terms of modes, provisionally termed molecular modes, that do have an exponential relaxation behavior. With care, the resulting Fredholm integral equation of the first kind can be inverted to recover the probability distribution of the molecular modes. The advantages and limitations of this approach are noted.
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Affiliation(s)
- D Asthagiri
- Rice University, Department of Chemical and Biomolecular Engineering, 6100 Main Street, Houston, Texas 77005, United States
| | - Walter G Chapman
- Rice University, Department of Chemical and Biomolecular Engineering, 6100 Main Street, Houston, Texas 77005, United States
| | - George J Hirasaki
- Rice University, Department of Chemical and Biomolecular Engineering, 6100 Main Street, Houston, Texas 77005, United States
| | - Philip M Singer
- Rice University, Department of Chemical and Biomolecular Engineering, 6100 Main Street, Houston, Texas 77005, United States
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Singer PM, Valiya Parambathu A, Wang X, Asthagiri D, Chapman WG, Hirasaki GJ, Fleury M. Elucidating the 1H NMR Relaxation Mechanism in Polydisperse Polymers and Bitumen Using Measurements, MD Simulations, and Models. J Phys Chem B 2020; 124:4222-4233. [PMID: 32356986 DOI: 10.1021/acs.jpcb.0c01941] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mechanism behind the 1H nuclear magnetic resonance (NMR) frequency dependence of T1 and the viscosity dependence of T2 for polydisperse polymers and bitumen remains elusive. We elucidate the matter through NMR relaxation measurements of polydisperse polymers over an extended range of frequencies (f0 = 0.01-400 MHz) and viscosities (η = 385-102 000 cP) using T1 and T2 in static fields, T1 field-cycling relaxometry, and T1ρ in the rotating frame. We account for the anomalous behavior of the log-mean relaxation times T1LM ∝ f0 and T2LM ∝ (η/T)-1/2 with a phenomenological model of 1H-1H dipole-dipole relaxation, which includes a distribution in molecular correlation times and internal motions of the nonrigid polymer branches. We show that the model also accounts for the anomalous T1LM and T2LM in previously reported bitumen measurements. We find that molecular dynamics (MD) simulations of the T1 ∝ f0 dispersion and T2 of similar polymers simulated over a range of viscosities (η = 1-1000 cP) are in good agreement with measurements and the model. The T1 ∝ f0 dispersion at high viscosities agrees with previously reported MD simulations of heptane confined in a polymer matrix, which suggests a common NMR relaxation mechanism between viscous polydisperse fluids and fluids under nanoconfinement, without the need to invoke paramagnetism.
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Affiliation(s)
- Philip M Singer
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, United States
| | - Arjun Valiya Parambathu
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, United States
| | - Xinglin Wang
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, United States
| | - Dilip Asthagiri
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, United States
| | - Walter G Chapman
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, United States
| | - George J Hirasaki
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, United States
| | - Marc Fleury
- IFP Energies nouvelles, 1 Avenue de Bois-Préau, 92852 Rueil-Malmaison, France
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