The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform

Nicholas P. Stadie - One of the best experts on this subject based on the ideXlab platform.

  • Unusual Entropy of Adsorbed Methane on Zeolite-Templated Carbon
    The Journal of Physical Chemistry C, 2015
    Co-Authors: Nicholas P. Stadie, Maxwell Murialdo, Channing C. Ahn, Brent Fultz
    Abstract:

    Methane Adsorption at high pressures and across a wide range of temperatures was investigated on the surface of three porous carbon adsorbents with complementary structural properties. The measured Adsorption equilibria were analyzed using a method that can accurately account for nonideal fluid properties and distinguish between absolute and excess quantities of Adsorption, and that also allows the direct calculation of the thermodynamic potentials relevant to Adsorption. On zeolite-templated carbon (ZTC), a material that exhibits extremely high surface area with optimal pore size and homogeneous structure, methane Adsorption occurs with unusual thermodynamic properties that are greatly beneficial for deliverable gas storage: an Enthalpy of Adsorption that increases with site occupancy, and an unusually low entropy of the adsorbed phase. The origin of these properties is elucidated by comparison of the experimental results with a statistical mechanical model. The results indicate that temperature-dependen...

  • Krypton Adsorption on Zeolite-Templated Carbon and Anomalous Surface Thermodynamics
    Langmuir : the ACS journal of surfaces and colloids, 2015
    Co-Authors: Maxwell Murialdo, Nicholas P. Stadie, Channing C. Ahn, Brent Fultz
    Abstract:

    Krypton Adsorption was measured at eight temperatures between 253 and 433 K on a zeolite-templated carbon and two commercial carbons. The data were fitted using a generalized Langmuir isotherm model and thermodynamic properties were extracted. Differing from that on commercial carbons, krypton Adsorption on the zeolite-templated carbon is accompanied by an increasing isosteric Enthalpy of Adsorption, rising by up to 1.4 kJ mol^(–1) as a function of coverage. This increase is a result of enhanced adsorbate–adsorbate interactions promoted by the ordered, nanostructured surface of the adsorbent. An assessment of the strength and nature of these adsorbate–adsorbate interactions is made by comparing the measured isosteric enthalpies of Adsorption (and other thermodynamic quantities) to fundamental metrics of intermolecular interactions of krypton and other common gases.

  • anomalous isosteric Enthalpy of Adsorption of methane on zeolite templated carbon
    Journal of the American Chemical Society, 2013
    Co-Authors: Nicholas P. Stadie, Maxwell Murialdo, B Fultz
    Abstract:

    A thermodynamic study of the Enthalpy of Adsorption of methane on high surface area carbonaceous materials was carried out from 238 to 526 K. The absolute quantity of adsorbed methane as a function of equilibrium pressure was determined by fitting isotherms to a generalized Langmuir-type equation. Adsorption of methane on zeolite-templated carbon, an extremely high surface area material with a periodic arrangement of narrow micropores, shows an increase in isosteric Enthalpy with methane occupancy; i.e., binding energies are greater as Adsorption quantity increases. The heat of Adsorption rises from 14 to 15 kJ/mol at near-ambient temperature and then falls to lower values at very high loading (above a relative site occupancy of 0.7), indicating that methane/methane interactions within the Adsorption layer become significant. The effect seems to be enhanced by a narrow pore-size distribution centered at 1.2 nm, approximately the width of two monolayers of methane, and reversible methane delivery increases by up to 20% over MSC-30 at temperatures and pressures near ambient.

Eva Díaz - One of the best experts on this subject based on the ideXlab platform.

  • Hydrocarbons Adsorption on metal trimesate Mofs: Inverse gas chromatography and immersion calorimetry studies
    Thermochimica Acta, 2015
    Co-Authors: Inés Gutiérrez, Eva Díaz, Salvador Ordóñez, Aurelio Vega, Antonio Guerrero-ruiz, Eva Castillejos-lópez, Inmaculada Rodríguez-ramos
    Abstract:

    Abstract Two commercial metal-organic frameworks, Cu 3 (BTC) 2 and Fe(BTC), have been selected to compare the Adsorption parameters obtained on these materials by two different techniques: immersion calorimetry and inverse gas chromatography (IGC), in order to find a relationship between thermodynamic parameters obtained by so different techniques. From comparison between the Enthalpy of Adsorption obtained from IGC and the Enthalpy of immersion, three molecules of the same number of carbon atoms have been selected: n- heptane, methylcyclohexane and toluene. Both by IGC and immersion calorimetry, the interaction is stronger in Fe(BTC), being the aromaticity of TOL determinant in the strength of the interaction. However, splitting of the Enthalpy of Adsorption into the dispersive and specific components allows to deduce that both parameters are more important on the Cu 3 (BTC) 2 , due to the higher available surface area in the case of the dispersive interaction; and for the specific interaction, due to the high potential of interaction into the micropores.

  • Characterization of nanocarbons (nanotubes and nanofibers) by Inverse Gas Chromatography
    Journal of Physics: Conference Series, 2007
    Co-Authors: Eva Díaz, Salvador Ordóñez, Aurelio Vega
    Abstract:

    The Adsorption of different alkanes (linear and cyclic), aromatics and chlorohydrocarbons on non-microporous carbons-carbon nanotubes (CNTs) and carbon nanofibres (CNFs)- was studied in this work by inverse gas chromatography (IGC). Capacity of Adsorption was derived from the isotherms of Adsorption, whereas thermodynamic properties (Enthalpy of Adsorption, surface free energy characteristics) have been determined from chromatographic retention data. CNTs present the highest Adsorption capacity. From surface free energy data, enthalpies of Adsorption of polar compounds were divided into dispersive and specific contributions. The interactions of cyclic (benzene and cyclohexane) and chlorinated compounds (trichloroethylene, tetrachloroethylene and chloroform) with the surfaces are mainly dispersive over all the carbons tested, being CNTs the material with the highest dispersive contribution. Adsorption parameters were correlated with morphological and chemical properties of the materials.

  • Adsorption of volatile organic compounds onto carbon nanotubes carbon nanofibers and high surface area graphites
    Journal of Colloid and Interface Science, 2007
    Co-Authors: Eva Díaz, Salvador Ordóñez, Aurelio Vega
    Abstract:

    Abstract The Adsorption of different alkanes (linear and cyclic), aromatics, and chlorohydrocarbons onto different nonmicroporous carbons—multiwalled carbon nanotubes (CNTs), carbon nanofibers (CNFs), and high-surface-area graphites (HSAGs)—is studied in this work by inverse gas chromatography (IGC). Capacity of Adsorption was derived from the isotherms of Adsorption, whereas thermodynamic properties (Enthalpy of Adsorption, surface free energy characteristics) have been determined from chromatographic retention data. HSAGs present the highest Adsorption capacity, followed by CNTs and CNFs (although CNTs present an intermediate surface area between the two HSAG studied). Among the different adsorbates tested, benzene exhibits the highest Adsorption capacity, and the same trend is observed in the Enthalpy of Adsorption. From surface free energy data, enthalpies of Adsorption of polar compounds were divided into dispersive and specific contributions. The interactions of cyclic (benzene and cyclohexane) and chlorinated compounds (trichloroethylene, tetrachloroethylene, and chloroform) with the surfaces are mainly dispersive over all the carbons tested, CNTs being the material with the highest dispersive contribution, as was deduced also from the entropy parameter. Adsorption parameters were correlated with morphological and chemical properties of the materials.

  • Adsorption characterisation of different volatile organic compounds over alumina, zeolites and activated carbon using inverse gas chromatography.
    Journal of chromatography. A, 2004
    Co-Authors: Eva Díaz, Salvador Ordóñez, Aurelio Vega, José Coca
    Abstract:

    Adsorption parameters (Enthalpy of Adsorption, free energy of Adsorption) of several alkanes, cyclic hydrocarbons, aromatic hydrocarbons and chlorinated compounds on different adsorbents (alumina, zeolites 13X and 5 A, and activated carbon) were determined by inverse gas chromatography. Dispersive surface energy interaction and specific interaction parameters were determined for each solute-adsorbent system. It was found that mesoporous alumina presents lower Enthalpy of Adsorption than the microporous materials. Furthermore, zeolite 13X, which has wider pores than zeolite 5 A, exhibits a higher Adsorption capacity.

  • Characterization of Co, Fe and Mn-exchanged zeolites by inverse gas chromatography.
    Journal of Chromatography A, 2004
    Co-Authors: Eva Díaz, Salvador Ordóñez, Aurelio Vega, José Coca
    Abstract:

    The Adsorption of several alkanes, cyclic hydrocarbons, aromatic hydrocarbons and chlorinated compounds on NaX, CaA, and exchanged Co, Mn and Fe zeolites as adsorbents was investigated. Zeolite composition and structure was determined by ICP-mass spectroscopy, XRD, and nitrogen Adsorption. Adsorption parameters (Enthalpy of Adsorption and free energy of Adsorption) as well as dispersive surface energy interaction and specific interaction parameters were determined for each solute–adsorbent system by inverse gas chromatography (IGC). The original zeolites NaX and CaA show the higher values of Enthalpy of Adsorption but specific interactions depend on the metal exchanged. Zeolites Mn–NaX and Co–NaX exhibit the strongest interactions with benzene, whereas zeolite Co–CaA shows the strongest interactions with chlorinated compounds. The trivalent cation (Fe3+) does not affect the either the Adsorption efficiency or specific interaction.

Brent Fultz - One of the best experts on this subject based on the ideXlab platform.

  • Unusual Entropy of Adsorbed Methane on Zeolite-Templated Carbon
    The Journal of Physical Chemistry C, 2015
    Co-Authors: Nicholas P. Stadie, Maxwell Murialdo, Channing C. Ahn, Brent Fultz
    Abstract:

    Methane Adsorption at high pressures and across a wide range of temperatures was investigated on the surface of three porous carbon adsorbents with complementary structural properties. The measured Adsorption equilibria were analyzed using a method that can accurately account for nonideal fluid properties and distinguish between absolute and excess quantities of Adsorption, and that also allows the direct calculation of the thermodynamic potentials relevant to Adsorption. On zeolite-templated carbon (ZTC), a material that exhibits extremely high surface area with optimal pore size and homogeneous structure, methane Adsorption occurs with unusual thermodynamic properties that are greatly beneficial for deliverable gas storage: an Enthalpy of Adsorption that increases with site occupancy, and an unusually low entropy of the adsorbed phase. The origin of these properties is elucidated by comparison of the experimental results with a statistical mechanical model. The results indicate that temperature-dependen...

  • Krypton Adsorption on Zeolite-Templated Carbon and Anomalous Surface Thermodynamics
    Langmuir : the ACS journal of surfaces and colloids, 2015
    Co-Authors: Maxwell Murialdo, Nicholas P. Stadie, Channing C. Ahn, Brent Fultz
    Abstract:

    Krypton Adsorption was measured at eight temperatures between 253 and 433 K on a zeolite-templated carbon and two commercial carbons. The data were fitted using a generalized Langmuir isotherm model and thermodynamic properties were extracted. Differing from that on commercial carbons, krypton Adsorption on the zeolite-templated carbon is accompanied by an increasing isosteric Enthalpy of Adsorption, rising by up to 1.4 kJ mol^(–1) as a function of coverage. This increase is a result of enhanced adsorbate–adsorbate interactions promoted by the ordered, nanostructured surface of the adsorbent. An assessment of the strength and nature of these adsorbate–adsorbate interactions is made by comparing the measured isosteric enthalpies of Adsorption (and other thermodynamic quantities) to fundamental metrics of intermolecular interactions of krypton and other common gases.

Aurelio Vega - One of the best experts on this subject based on the ideXlab platform.

  • Hydrocarbons Adsorption on metal trimesate Mofs: Inverse gas chromatography and immersion calorimetry studies
    Thermochimica Acta, 2015
    Co-Authors: Inés Gutiérrez, Eva Díaz, Salvador Ordóñez, Aurelio Vega, Antonio Guerrero-ruiz, Eva Castillejos-lópez, Inmaculada Rodríguez-ramos
    Abstract:

    Abstract Two commercial metal-organic frameworks, Cu 3 (BTC) 2 and Fe(BTC), have been selected to compare the Adsorption parameters obtained on these materials by two different techniques: immersion calorimetry and inverse gas chromatography (IGC), in order to find a relationship between thermodynamic parameters obtained by so different techniques. From comparison between the Enthalpy of Adsorption obtained from IGC and the Enthalpy of immersion, three molecules of the same number of carbon atoms have been selected: n- heptane, methylcyclohexane and toluene. Both by IGC and immersion calorimetry, the interaction is stronger in Fe(BTC), being the aromaticity of TOL determinant in the strength of the interaction. However, splitting of the Enthalpy of Adsorption into the dispersive and specific components allows to deduce that both parameters are more important on the Cu 3 (BTC) 2 , due to the higher available surface area in the case of the dispersive interaction; and for the specific interaction, due to the high potential of interaction into the micropores.

  • Characterization of nanocarbons (nanotubes and nanofibers) by Inverse Gas Chromatography
    Journal of Physics: Conference Series, 2007
    Co-Authors: Eva Díaz, Salvador Ordóñez, Aurelio Vega
    Abstract:

    The Adsorption of different alkanes (linear and cyclic), aromatics and chlorohydrocarbons on non-microporous carbons-carbon nanotubes (CNTs) and carbon nanofibres (CNFs)- was studied in this work by inverse gas chromatography (IGC). Capacity of Adsorption was derived from the isotherms of Adsorption, whereas thermodynamic properties (Enthalpy of Adsorption, surface free energy characteristics) have been determined from chromatographic retention data. CNTs present the highest Adsorption capacity. From surface free energy data, enthalpies of Adsorption of polar compounds were divided into dispersive and specific contributions. The interactions of cyclic (benzene and cyclohexane) and chlorinated compounds (trichloroethylene, tetrachloroethylene and chloroform) with the surfaces are mainly dispersive over all the carbons tested, being CNTs the material with the highest dispersive contribution. Adsorption parameters were correlated with morphological and chemical properties of the materials.

  • Adsorption of volatile organic compounds onto carbon nanotubes carbon nanofibers and high surface area graphites
    Journal of Colloid and Interface Science, 2007
    Co-Authors: Eva Díaz, Salvador Ordóñez, Aurelio Vega
    Abstract:

    Abstract The Adsorption of different alkanes (linear and cyclic), aromatics, and chlorohydrocarbons onto different nonmicroporous carbons—multiwalled carbon nanotubes (CNTs), carbon nanofibers (CNFs), and high-surface-area graphites (HSAGs)—is studied in this work by inverse gas chromatography (IGC). Capacity of Adsorption was derived from the isotherms of Adsorption, whereas thermodynamic properties (Enthalpy of Adsorption, surface free energy characteristics) have been determined from chromatographic retention data. HSAGs present the highest Adsorption capacity, followed by CNTs and CNFs (although CNTs present an intermediate surface area between the two HSAG studied). Among the different adsorbates tested, benzene exhibits the highest Adsorption capacity, and the same trend is observed in the Enthalpy of Adsorption. From surface free energy data, enthalpies of Adsorption of polar compounds were divided into dispersive and specific contributions. The interactions of cyclic (benzene and cyclohexane) and chlorinated compounds (trichloroethylene, tetrachloroethylene, and chloroform) with the surfaces are mainly dispersive over all the carbons tested, CNTs being the material with the highest dispersive contribution, as was deduced also from the entropy parameter. Adsorption parameters were correlated with morphological and chemical properties of the materials.

  • Adsorption characterisation of different volatile organic compounds over alumina, zeolites and activated carbon using inverse gas chromatography.
    Journal of chromatography. A, 2004
    Co-Authors: Eva Díaz, Salvador Ordóñez, Aurelio Vega, José Coca
    Abstract:

    Adsorption parameters (Enthalpy of Adsorption, free energy of Adsorption) of several alkanes, cyclic hydrocarbons, aromatic hydrocarbons and chlorinated compounds on different adsorbents (alumina, zeolites 13X and 5 A, and activated carbon) were determined by inverse gas chromatography. Dispersive surface energy interaction and specific interaction parameters were determined for each solute-adsorbent system. It was found that mesoporous alumina presents lower Enthalpy of Adsorption than the microporous materials. Furthermore, zeolite 13X, which has wider pores than zeolite 5 A, exhibits a higher Adsorption capacity.

  • Characterization of Co, Fe and Mn-exchanged zeolites by inverse gas chromatography.
    Journal of Chromatography A, 2004
    Co-Authors: Eva Díaz, Salvador Ordóñez, Aurelio Vega, José Coca
    Abstract:

    The Adsorption of several alkanes, cyclic hydrocarbons, aromatic hydrocarbons and chlorinated compounds on NaX, CaA, and exchanged Co, Mn and Fe zeolites as adsorbents was investigated. Zeolite composition and structure was determined by ICP-mass spectroscopy, XRD, and nitrogen Adsorption. Adsorption parameters (Enthalpy of Adsorption and free energy of Adsorption) as well as dispersive surface energy interaction and specific interaction parameters were determined for each solute–adsorbent system by inverse gas chromatography (IGC). The original zeolites NaX and CaA show the higher values of Enthalpy of Adsorption but specific interactions depend on the metal exchanged. Zeolites Mn–NaX and Co–NaX exhibit the strongest interactions with benzene, whereas zeolite Co–CaA shows the strongest interactions with chlorinated compounds. The trivalent cation (Fe3+) does not affect the either the Adsorption efficiency or specific interaction.

Maxwell Murialdo - One of the best experts on this subject based on the ideXlab platform.

  • Unusual Entropy of Adsorbed Methane on Zeolite-Templated Carbon
    The Journal of Physical Chemistry C, 2015
    Co-Authors: Nicholas P. Stadie, Maxwell Murialdo, Channing C. Ahn, Brent Fultz
    Abstract:

    Methane Adsorption at high pressures and across a wide range of temperatures was investigated on the surface of three porous carbon adsorbents with complementary structural properties. The measured Adsorption equilibria were analyzed using a method that can accurately account for nonideal fluid properties and distinguish between absolute and excess quantities of Adsorption, and that also allows the direct calculation of the thermodynamic potentials relevant to Adsorption. On zeolite-templated carbon (ZTC), a material that exhibits extremely high surface area with optimal pore size and homogeneous structure, methane Adsorption occurs with unusual thermodynamic properties that are greatly beneficial for deliverable gas storage: an Enthalpy of Adsorption that increases with site occupancy, and an unusually low entropy of the adsorbed phase. The origin of these properties is elucidated by comparison of the experimental results with a statistical mechanical model. The results indicate that temperature-dependen...

  • Krypton Adsorption on Zeolite-Templated Carbon and Anomalous Surface Thermodynamics
    Langmuir : the ACS journal of surfaces and colloids, 2015
    Co-Authors: Maxwell Murialdo, Nicholas P. Stadie, Channing C. Ahn, Brent Fultz
    Abstract:

    Krypton Adsorption was measured at eight temperatures between 253 and 433 K on a zeolite-templated carbon and two commercial carbons. The data were fitted using a generalized Langmuir isotherm model and thermodynamic properties were extracted. Differing from that on commercial carbons, krypton Adsorption on the zeolite-templated carbon is accompanied by an increasing isosteric Enthalpy of Adsorption, rising by up to 1.4 kJ mol^(–1) as a function of coverage. This increase is a result of enhanced adsorbate–adsorbate interactions promoted by the ordered, nanostructured surface of the adsorbent. An assessment of the strength and nature of these adsorbate–adsorbate interactions is made by comparing the measured isosteric enthalpies of Adsorption (and other thermodynamic quantities) to fundamental metrics of intermolecular interactions of krypton and other common gases.

  • anomalous isosteric Enthalpy of Adsorption of methane on zeolite templated carbon
    Journal of the American Chemical Society, 2013
    Co-Authors: Nicholas P. Stadie, Maxwell Murialdo, B Fultz
    Abstract:

    A thermodynamic study of the Enthalpy of Adsorption of methane on high surface area carbonaceous materials was carried out from 238 to 526 K. The absolute quantity of adsorbed methane as a function of equilibrium pressure was determined by fitting isotherms to a generalized Langmuir-type equation. Adsorption of methane on zeolite-templated carbon, an extremely high surface area material with a periodic arrangement of narrow micropores, shows an increase in isosteric Enthalpy with methane occupancy; i.e., binding energies are greater as Adsorption quantity increases. The heat of Adsorption rises from 14 to 15 kJ/mol at near-ambient temperature and then falls to lower values at very high loading (above a relative site occupancy of 0.7), indicating that methane/methane interactions within the Adsorption layer become significant. The effect seems to be enhanced by a narrow pore-size distribution centered at 1.2 nm, approximately the width of two monolayers of methane, and reversible methane delivery increases by up to 20% over MSC-30 at temperatures and pressures near ambient.