Phase Equilibria in Carbon Dioxide Expanded Solvents:  Experiments and Molecular Simulations

Houndonougbo, Yao; Jin, Hong Ju; Rajagopalan, Bhuma; Wong, Kean; Kuczera, Krzysztof; Subramaniam, Bala; Laird, Brian B.

doi:10.1021/jp061592w

Cited by 59 publications

(54 citation statements)

References 48 publications

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“…[42][43][44] Although the pressure-tunable properties of these media have been exploited in chemocatalysis in av ariety of ways, [45,46] the high CO 2 solubility in such media has not been previously harnessed to promote enhanced electrocatalytic CO 2 conversion. [42][43][44] Although the pressure-tunable properties of these media have been exploited in chemocatalysis in av ariety of ways, [45,46] the high CO 2 solubility in such media has not been previously harnessed to promote enhanced electrocatalytic CO 2 conversion.…”

Section: Resultsmentioning

confidence: 99%

Intensified Electrocatalytic CO₂ Conversion in Pressure‐Tunable CO₂‐Expanded Electrolytes

et al. 2019

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Multimolar CO2 concentrations are achieved in acetonitrile solutions containing supporting electrolyte at relatively mild CO2 pressures (<5 MPa) and ambient temperature. Such CO2‐rich, electrolyte‐containing solutions are termed as CO2‐eXpanded Electrolytes (CXEs) because significant volumetric expansion of the liquid phase accompanies CO2 dissolution. Cathodic polarization of a model polycrystalline gold electrode‐catalyst in CXE media enhances CO2 to CO conversion rates by up to an order of magnitude compared with those attainable at near‐ambient pressures, without loss of selectivity. The observed catalytic process intensification stems primarily from markedly increased CO2 availability. However, a non‐monotonic correlation between the dissolved CO2 concentration and catalytic activity is observed, with an optimum occurring at approximately 5 m CO2 concentration. At the highest applied CO2 pressures, catalysis is significantly attenuated despite higher CO2 concentrations and improved mass‐transport characteristics, attributed in part to increased solution resistance. These results reveal that pressure‐tunable CXE media can significantly intensify CO2 reduction rates over known electrocatalysts by alleviating substrate starvation, with CO2 pressure as a crucial variable for optimizing the efficiency of electrocatalytic CO2 conversion.

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Section: Resultsmentioning

confidence: 99%

Intensified Electrocatalytic CO₂ Conversion in Pressure‐Tunable CO₂‐Expanded Electrolytes

et al. 2019

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“…OPLS-AA (Optimized Potentials for Liquid Simulation-All Atoms) [29][30][31][32][33] was used for Ph-C n and EPM2 (elementary physical model) 34,35 force field for CO 2 , respectively. Simulations were performed with GROMACS 4.0.7 software.…”

Section: Methodsmentioning

confidence: 99%

Molecular dynamics simulation of diffusion coefficients and structural properties of some alkylbenzenes in supercritical carbon dioxide at infinite dilution

Wang

Zhong

Feng

et al. 2014

The Journal of Chemical Physics

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The binary infinite dilute diffusion coefficients, D₁₂(∞), of some alkylbenzenes (Ph-C(n), from Ph-H to Ph-C12) from 313 K to 333 K at 15 MPa in supercritical carbon dioxide (scCO2) have been studied by molecular dynamics (MD) simulation. The MD values agree well with the experimental ones, which indicate MD simulation technique is a powerful way to predict and obtain diffusion coefficients of solutes in supercritical fluids. Besides, the local structures of Ph-C(n)/CO2 fluids are further investigated by calculating radial distribution functions and coordination numbers. It qualitatively convinces that the first solvation shell of Ph-C(n) in scCO2 is significantly influenced by the structure of Ph-C(n) solute. Meanwhile, the mean end-to-end distance, the mean radius of gyration and dihedral angle distribution are calculated to gain an insight into the structural properties of Ph-C(n) in scCO2. The abnormal trends of radial distribution functions and coordination numbers can be reasonably explained in term of molecular flexibility. Moreover, the computed results of dihedral angle clarify that flexibility of long-chain Ph-C(n) is the result of internal rotation of C-C single bond (σ(c-c)) in alkyl chain. It is interesting that compared with n-alkane, because of the existence of benzene ring, the flexibility of alkyl chain in Ph-C(n) with same carbon atom number is significantly reduced, as a result, the carbon chain dependence of diffusion behaviors for long-chain n-alkane (n ≥ 5) and long-chain Ph-C(n) (n ≥ 4) in scCO2 are different.

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“…Recent CEBC contributions include studies of several catalytic processes in CO 2 expanded solvents, [4][5][6][7] as well as modeling of the vapor-liquid equilibria of several CO 2 -expanded organic liquids. 8 In this paper we continue our studies of CO 2 -expanded organic liquids, presenting results of simulations of transport properties for a series of CO 2 -acetonitrile mixtures of varying composition. We use previously published potential energy functions of CO 2 ͑Ref.…”

Section: Introductionmentioning

confidence: 91%

Transport properties of CO2-expanded acetonitrile from molecular dynamics simulations

Houndonougbo

Laird

Kuczera

2007

The Journal of Chemical Physics

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Carbon-dioxide-expanded liquids, which are mixtures of organic liquids and compressed CO 2 , are novel media used in chemical processing. The authors present a molecular simulation study of the transport properties of liquid mixtures formed by acetonitrile and carbon dioxide, in which the CO 2 mole fraction is adjusted by changing the pressure, at a constant temperature of 298 K. They report values of translational diffusion coefficients, rotational correlation times, and shear viscosities of the liquids as function of CO 2 mole fraction. The simulation results are in good agreement with the available experimental data for the pure components and provide interesting insights into the largely unknown properties of the mixtures, which are being recognized as important novel materials in chemical operations. We find that the calculated quantities exhibit smooth variation with composition that may be represented by simple model equations. The translational and rotational diffusion rates increase with CO 2 mole fraction for both the acetonitrile and carbon dioxide components. The shear viscosity decreases with increasing amount of CO 2 , varying smoothly between the values of pure acetonitrile and pure carbon dioxide. Our results show that adjusting the amount of CO 2 in the mixture allows the variation of transport rates by a factor of 3-4 and liquid viscosity by a factor of 8. Thus, the physical properties of the mixture may be tailored to the desired range by changes in the operating conditions of temperature and pressure.

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Phase Equilibria in Carbon Dioxide Expanded Solvents: Experiments and Molecular Simulations

Cited by 59 publications

References 48 publications

Intensified Electrocatalytic CO₂ Conversion in Pressure‐Tunable CO₂‐Expanded Electrolytes

Intensified Electrocatalytic CO₂ Conversion in Pressure‐Tunable CO₂‐Expanded Electrolytes

Molecular dynamics simulation of diffusion coefficients and structural properties of some alkylbenzenes in supercritical carbon dioxide at infinite dilution

Transport properties of CO2-expanded acetonitrile from molecular dynamics simulations

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Phase Equilibria in Carbon Dioxide Expanded Solvents: Experiments and Molecular Simulations

Cited by 59 publications

References 48 publications

Intensified Electrocatalytic CO2 Conversion in Pressure‐Tunable CO2‐Expanded Electrolytes

Intensified Electrocatalytic CO2 Conversion in Pressure‐Tunable CO2‐Expanded Electrolytes

Molecular dynamics simulation of diffusion coefficients and structural properties of some alkylbenzenes in supercritical carbon dioxide at infinite dilution

Transport properties of CO2-expanded acetonitrile from molecular dynamics simulations

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Product

Resources

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Intensified Electrocatalytic CO₂ Conversion in Pressure‐Tunable CO₂‐Expanded Electrolytes

Intensified Electrocatalytic CO₂ Conversion in Pressure‐Tunable CO₂‐Expanded Electrolytes