Adsorption of Gases on Zeolitic Imidazolate Frameworks: Modeling with Equations of State for Confined Fluids and Pore Size Distribution Estimation

Barbosa, Gabriel D.; Travalloni, Leonardo; Tavares, Frederico W.; Castier, Marcelo

doi:10.1021/acs.iecr.9b05221

Cited by 4 publications

(4 citation statements)

References 47 publications

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“…While our simulations use LJ potentials, conventional for argon–argon and argon–silica interactions, the TvdW EOS is based on the square-well potential. The next steps toward connecting molecular simulation with EOS would be the following: first, to compare the TvdW EOS with simulation data for the square-well fluid and second, to derive the equation for the elastic modulus for more advanced EOS for confined fluids, such as those based on Peng–Robinson EOS. − We expect that the latter could provide quantitative agreement with the LJ fluid. However, we will leave these steps for future work.…”

Section: Discussionmentioning

confidence: 99%

“…Their model allows directly solving the chemical equilibrium condition of the chemical potential of the bulk fluid matching that of the adsorbed fluid μ ads = μ bulk to determine the vapor–liquid equilibrium in the pore. Travalloni and co-workers also extended this method for other pore models and equations of state. − Their approach is also applicable to modeling the competitive adsorption of fluid mixtures, which showed good comparisons to experiments. − …”

Section: Introductionmentioning

confidence: 99%

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Compressibility of a Simple Fluid in Cylindrical Confinement: Molecular Simulation and Equation of State Modeling

Dobrzanski

Corrente

Gor

2020

Ind. Eng. Chem. Res.

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Fluids confined in nanoporous materials exhibit thermodynamic properties that differ from the same fluid in bulk. Recent experiments and molecular simulations suggested that the isothermal compressibility is among these properties. The compressibility determines the elastic response of a fluid to mechanical impact, and in particular, the speed of acoustic wave propagation through it. Knowledge of the compressibility of fluids confined in nanopores is needed for understanding the elastic wave propagation in fluid-saturated nanoporous media, such as hydrocarbon-bearing shales. Molecular simulations allow for the prediction of the elastic properties of a confined fluid but require computationally expensive calculations for each system and pore size. Therefore, there is interest for a more straightforward model that can predict the elastic properties of a confined fluid as a function of the external pressure and confining pore size. Such models can be based on an equation of state (EOS) for a confined system. Here, we explore a possibility for a generalized van der Waals EOS for confined fluids to predict the compressibility. We also calculate the elastic properties of argon confined in silica nanopores from grand canonical Monte Carlo simulations. We obtain comparable adsorption isotherm predictions of the EOS and simulations at various pore sizes and temperatures without changing any other parameters. We then see how the predictions of the elastic properties from simulations compare to the EOS and find reasonable agreement. Additionally, we vary the solid–fluid interaction parameters in both the EOS and molecular simulations to represent solids other than silica and see how the elastic moduli depend on the other properties of confining pores related to the interaction strength. This work is a step toward a quantitative description of wave propagation in fluid-saturated nanoporous media.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Compressibility of a Simple Fluid in Cylindrical Confinement: Molecular Simulation and Equation of State Modeling

Dobrzanski

Corrente

Gor

2020

Ind. Eng. Chem. Res.

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“…MOFs, that is, metal organic frameworks, exhibit extensive 3D structures and are prepared by linking together the tetrahedral metal ions and the imidazolate linkers. These materials have particular pore sizes, unique chemical properties, and large surface area, which enable them to find utility in the field of separation. − ZIFs (zeolitic imidazolate frameworks), an important category in MOF materials, possess ultra-microporosities, great chemical stability, and thermostability when compared with other MOFs. , ZIFs have been widely used to adsorb and separate gases and have also been found in the fields of pervaporation, chemocatalysis, and sensors. − ZIF-8, the classical ZIF compound that has a sodalite zeolite-type structure, is a suggested candidate material for membrane-based applications. − The in situ growth, secondary seeding growth, and interfacial and vapor-phase processing methods as well as contra-diffusion techniques have so far been explored for MOF membrane synthesis. − MOF membranes without defects are not easy to be prepared by the in situ solvothermal approaches because the MOF heterogeneous nucleation density is low in the supports. Support chemistry exerts an important influence on the synthesis of membranes.…”

Section: Introductionmentioning

confidence: 99%

Preparation of ZIF-8 Membranes on Porous ZnO Hollow Fibers by a Facile ZnO-Induced Method

Wang

Chen

Wang

et al. 2020

Ind. Eng. Chem. Res.

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In the present study, a simple method for the synthesis of the ZIF-8 membrane has been proposed. This method involves growing the ZIF-8 layer onto the external surface of the ZnO porous hollow support, with inner and outer diameters of 1.55 mm and 2.06 mm, respectively. The ZnO hollow fibers with a thin spongy layer and large numbers of finger-like pores were prepared by a phase inversion/sintering technique. These ZnO hollow fibers have proved to be effective supports for the preparation of highly stable and reproducible ZIF-8 membranes. The ZnO support helps in seeding the ZIF-8 membrane formation and then serves as a connecting bridge to link the support with the membrane. The excellent binding strength between ZIF-8 and the support is responsible for the superior mechanical and thermal stabilities of the ZIF-8 membranes. These membranes exhibited great hydrogen permeation (1.2 × 10–6 mol·m–2·s–1·Pa–1) and attained the ideal separation factors for H2/CO2, H2/N2, and H2/CH4 at 7.0, 4.3, and 3.7, respectively, demonstrating good molecular sieve performance. These ZIF-8 membranes displayed preferential adsorption of CO2 and can be potentially applied in CO2 capture from industrial mixed gases. This method requires neither high smoothness of the support surface nor modification of the support, thus providing a simple and comparable technique for the preparation of tubular ZIF and additional MOF membranes.

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“…To accurately model the fluids in nanopores, the EOS needs to be developed with the effects of confinement in mind. Recently, there have been a number of attempts to model fluids under confinement using an EOS [63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80]. However, none of those works have been developed for the elastic properties.…”

Section: Local Elastic Propertiesmentioning

confidence: 99%

Elastic properties of confined fluids from molecular modeling to ultrasonic experiments on porous solids

Dobrzanski

Gurevich

Gor

2021

Applied Physics Reviews

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Fluids confined in nanopores are ubiquitous in nature and technology. In recent years, the interest in confined fluids has grown, driven by research on unconventional hydrocarbon resources -shale gas and shale oil, much of which are confined in nanopores. When fluids are confined in nanopores, many of their properties differ from those of the same fluid in the bulk. These properties include density, freezing point, transport coefficients, thermal expansion coefficient, and elastic properties. The elastic moduli of a fluid confined in the pores contribute to the overall elasticity of the fluid-saturated porous medium and determine the speed at which elastic waves traverse through the medium. Wave propagation in fluid-saturated porous media is pivotal for geophysics, as elastic waves are used for characterization of formations and rock samples. In this paper, we present a comprehensive review of experimental works on wave propagation in fluid-saturated nanoporous media, as well as theoretical works focused on calculation of compressibility of fluids in confinement. We discuss models that bridge the gap between experiments and theory, revealing a number of open questions that are both fundamental and applied in nature. While some results were demonstrated both experimentally and theoretically (e.g. the pressure dependence of compressibility of fluids), others were theoretically predicted, but not verified in experiments (e.g. linear scaling of modulus with the pore size). Therefore, there is a demand for the combined experimental-modeling studies on porous samples with various characteristic pore sizes. The extension of molecular simulation studies from simple model fluids to the more complex molecular fluids is another open area of practical interest.

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Adsorption of Gases on Zeolitic Imidazolate Frameworks: Modeling with Equations of State for Confined Fluids and Pore Size Distribution Estimation

Cited by 4 publications

References 47 publications

Compressibility of a Simple Fluid in Cylindrical Confinement: Molecular Simulation and Equation of State Modeling

Compressibility of a Simple Fluid in Cylindrical Confinement: Molecular Simulation and Equation of State Modeling

Preparation of ZIF-8 Membranes on Porous ZnO Hollow Fibers by a Facile ZnO-Induced Method

Elastic properties of confined fluids from molecular modeling to ultrasonic experiments on porous solids

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