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Carlos Otero Areán - One of the best experts on this subject based on the ideXlab platform.
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molar entropy and Enthalpy of co adsorbed in zeolites as derived from vtir data role of intermolecular modes
ChemistryOpen, 2020Co-Authors: Edoardo Garrone, Carlos Otero Areán, Montserrat Rodríguez Delgado, Barbara BonelliAbstract:Detailed analysis of recently reported variable-temperature IR (VTIR) spectra of carbon monoxide adsorbed in alkaline zeolites shows how, not only the corresponding values of standard Adsorption Enthalpy ( Δ H 0 ) and entropy ( Δ S 0 ) can be obtained, but also the thermodynamic values of molar entropy and Enthalpy which characterize the adsorbed gas phase. In addition, it is shown that the so obtained molar entropy data can lead to new insights into soft molecular modes, which would be hardly accessible by conventional IR spectroscopic techniques.
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non linear Enthalpy entropy correlation for nitrogen Adsorption in zeolites
Molecules, 2018Co-Authors: Montserrat Rodríguez Delgado, Carlos Otero AreánAbstract:The thermodynamics of dinitrogen Adsorption in faujasite-type zeolites, Na-Y, Ca-Y and Sr-Y, were investigated by means of variable-temperature infrared spectroscopy, a technique that affords determination of the standard Adsorption Enthalpy (ΔH⁰) and entropy (ΔS⁰) from an analysis of the IR spectra recorded over a range of temperatures. The results obtained, taken together with previously reported values for N₂ Adsorption on protonic zeolites, revealed a non-linear correlation between ΔH⁰ and ΔS⁰. Implications of such a correlation for gas separation and purification by Adsorption in porous solids are highlighted.
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controlling the Adsorption Enthalpy of co2 in zeolites by framework topology and composition
Chemsuschem, 2012Co-Authors: Lukas Grajciar, Carlos Otero Areán, Gemma Turnes Palomino, Jiři Cejka, Arnost Zukal, Petr NachtigallAbstract:Zeolites are often investigated as potential adsorbents for CO(2) Adsorption and separation. Depending on the zeolite topology and composition (Si/Al ratio and extra-framework cations), the CO(2) Adsorption heats at low coverages vary from -20 to -60 kJ mol(-1), and with increasing surface coverage Adsorption heats either stay approximately constant or they quickly drop down. Experimental Adsorption heats obtained for purely siliceous porous solids and for ion-exchanged zeolites of the structural type MFI, FER, FAU, LTA, TUN, IMF, and -SVR are discussed in light of results of periodic density functional theory calculations corrected for the description of dispersion interactions. Key factors influencing the stability of CO(2) Adsorption complexes are identified and discussed at the molecular level. A general model for CO(2) Adsorption in zeolites and related materials is proposed and data reported in literature are evaluated with regard to the proposed model.
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infrared spectroscopic and thermodynamic study on hydrogen Adsorption on the metal organic framework mil 100 sc
Chemical Physics Letters, 2012Co-Authors: Carlos Otero Areán, Carlos Palomino Cabello, Gemma Turnes PalominoAbstract:Abstract The thermodynamics of hydrogen interaction with coordinatively unsaturated Sc III cationic sites in the metal organic framework MIL-100(Sc) was studied by variable temperature infrared spectroscopy. Simultaneous measurement of the hydrogen equilibrium pressure (inside a closed IR cell) and the integrated IR absorbance over the temperature range 80–125 K led to the determination of the corresponding values of standard Adsorption Enthalpy and entropy, which resulted to be Δ H 0 = −11.2 (±1) kJ mol −1 and Δ S 0 = −120 (±10) J mol −1 K −1 . The Enthalpy value is among the largest reported so far for hydrogen Adsorption on MOFs.
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Enthalpy entropy correlation for hydrogen Adsorption on mofs variable temperature ftir study of hydrogen Adsorption on mil 100 cr and mil 101 cr
European Journal of Inorganic Chemistry, 2011Co-Authors: Gemma Turnes Palomino, Carlos Palomino Cabello, Carlos Otero AreánAbstract:The thermodynamics of hydrogen interaction with the coordinatively unsaturated Cr III cationic sites in the metal–organic frameworks MIL-100(Cr) and MIL-101(Cr) was studied by variable-temperature infrared (VTIR) spectroscopy. Simultaneous measurement of the equilibrium pressure of hydrogen and the integrated IR absorbance over the temperature range 79–105 K led to the determination of the corresponding values of standard Adsorption Enthalpy (ΔH 0 )a nd entropy (ΔS 0 ). For MIL-100(Cr) these values were ΔH 0 =
Joeri F M Denayer - One of the best experts on this subject based on the ideXlab platform.
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understanding hydrocarbon Adsorption in the uio 66 metal organic framework separation of un saturated linear branched cyclic adsorbates including stereoisomers
Journal of Physical Chemistry C, 2013Co-Authors: Tim Duerinck, Gino V Baron, Rocio Buenoperez, Frederik Vermoortele, Dirk De Vos, Sofia Calero, Joeri F M DenayerAbstract:The low coverage Adsorption properties of alkanes, alkenes, and aromatics of the linear, branched, and cyclic type (ca. 70 molecules) were studied using inverse pulse gas chromatography at zero coverage on the zirconium metal–organic framework UiO-66 and its functionalized analogues UiO-66-Me, UiO-66-NO2, UiO-66-Me2 in the temperature range 433–573 K. In our study, we determined and analyzed the Adsorption Enthalpy, Henry constants, and entropic factors. Preferential Adsorption of bulky molecules is observed with specific adsorbate and cage size effects, yielding very specific, preferential Adsorption. Remarkably high Adsorption selectivity factors (up to 14) for cyclo- compared to n-alkanes were found. The presence of additional groups (methyl, nitro) on the linkers in the framework influences Adsorption properties significantly, mainly by reducing the effective pore size. Whereas increased selectivity is observed for UiO-66-Me, this effect decreases again upon addition of a second methyl group, UiO-66-M...
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low coverage Adsorption properties of the metal organic framework mil 47 studied by pulse chromatography and monte carlo simulations
Physical Chemistry Chemical Physics, 2009Co-Authors: Vincent Finsy, Gino V Baron, Dirk De Vos, Sofia Calero, Elena Garciaperez, Patrick J Merkling, Gill Vedts, Joeri F M DenayerAbstract:Low-coverage Adsorption properties of the metal–organic framework MIL-47 were determined by a combined experimental and simulation study. Henry constants and low coverage Adsorption enthalpies of C5–C8 linear and branched alkanes, cyclohexane and benzene were measured from 120 to 240 °C using pulse gas chromatography. An adapted force field for linear and branched alkanes in MIL-47 was used to compute the Adsorption properties of those molecules. A new set of charges was developed for simulations with benzene in MIL-47. The Adsorption Enthalpy of linear alkanes increases with about 7.6 kJ mol−1 per additional –CH2– group. Henry Adsorption constants of iso-alkanes are slightly lower than those of the linear chains but the MIL-47 framework is not imposing steric constraints on the branched chains. Benzene and cyclohexane are adsorbed less strongly than n-hexane as they have less hydrogen atoms. For the studied non-polar molecules, the Adsorption energies are dominated by van der Waals interactions and benzene Adsorption is additionally influenced by Coulombic interactions. The simulated tendencies are in good agreement with the experiments.
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investigation of inverse shape selectivity in alkane Adsorption on sapo 5 zeolite using the tracer chromatography technique
Journal of Catalysis, 2004Co-Authors: Johan A Martens, Joeri F M Denayer, Ahmet Ocakoglu, Gino V BaronAbstract:Abstract Adsorption of linear and branched alkanes (C4–C8 range) on a microporous silicoaluminophosphate material (SAPO-5) was studied using the chromatographic technique at 353–573 K. Under these experimental conditions of low micropore occupancy specific branched molecules adsorb preferentially over the corresponding linear isomers. Such inverse shape selectivity was encountered with isobutane, isopentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, and 2,2-dimethylhexane. Other skeletal isomers exhibit the conventional shape selectivity; i.e., their Adsorption is less favorable compared to the linear alkane with the same carbon number. The occurrence of inverse shape selectivity versus conventional shape selectivity can be explained in terms of compensation between the Adsorption Enthalpy and entropy. The branched species that exhibit inverse shape selectivity have a higher Adsorption Enthalpy compared to the linear chains, counterbalancing the negative contribution of Adsorption entropy to the Adsorption equilibrium.
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tracer chromatographic study of pore and pore mouth Adsorption of linear and monobranched alkanes on zsm 22 zeolite
Journal of Physical Chemistry B, 2003Co-Authors: Refik A Ocakoglu, Johan A Martens, Joeri F M Denayer, Guy Marin, G V BaronAbstract:The Adsorption equilibria of a series of n-alkanes and 2-methyl- and 3-methyl-branched alkanes in the C5−C9 range on ZSM-22 zeolite samples were determined using the tracer chromatographic technique at temperatures between 343 and 623 K. Adsorption experiments were performed with a calcined ZSM-22 sample referred to as “open” ZSM-22 and an as-synthesized ZSM-22 zeolite sample in which the 1,6-diaminohexane template was left inside the pores, denoted as “closed” ZSM-22. In the “open” ZSM-22, the zeolite micropores are available for Adsorption. In the “closed” ZSM-22, Adsorption can occur in the pore mouths and on the external surface. The closing of the channels of ZSM-22 results in a significant decrease in the Henry constant and Adsorption Enthalpy and entropy of linear alkane molecules. Contrarily, the Adsorption Enthalpy and entropy of branched alkanes on “open” and “closed” ZSM-22 are nearly identical, indicating that the preferred Adsorption sites for monobranched alkanes are not located inside the p...
Mumtaz A. Quraishi - One of the best experts on this subject based on the ideXlab platform.
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inhibition of mild steel corrosion in acid solution by pheniramine drug experimental and theoretical study
Corrosion Science, 2010Co-Authors: Ishtiaque Ahamad, Rajendra Prasad, Mumtaz A. QuraishiAbstract:Inhibition of mild steel corrosion in 1 M HCl solution by Pheniramine drug was studied using weight loss, electrochemical impedance spectroscopy, linear polarization resistance, and potentiodynamic polarization measurements. The values of activation energy (Ea) and different thermodynamic parameters such as Adsorption equilibrium constant (Kads), free energy of Adsorption (ΔGads°), Adsorption Enthalpy (ΔHads°) and Adsorption entropy (ΔSads°) were calculated and discussed. The Adsorption process of studied drug on mild steel surface obeys the Langmuir Adsorption isotherm. Potentiodynamic polarization measurements showed that Pheniramine is mixed-type inhibitor. Further, theoretical calculations were carried out and relations between computed parameters and experimental inhibition efficiency were discussed.
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inhibition of mild steel corrosion in acid solution by pheniramine drug experimental and theoretical study
Corrosion Science, 2010Co-Authors: Ishtiaque Ahamad, Rajendra Prasad, Mumtaz A. QuraishiAbstract:Inhibition of mild steel corrosion in 1 M HCl solution by Pheniramine drug was studied using weight loss, electrochemical impedance spectroscopy, linear polarization resistance, and potentiodynamic polarization measurements. The values of activation energy (Ea) and different thermodynamic parameters such as Adsorption equilibrium constant (Kads), free energy of Adsorption (ΔGads°), Adsorption Enthalpy (ΔHads°) and Adsorption entropy (ΔSads°) were calculated and discussed. The Adsorption process of studied drug on mild steel surface obeys the Langmuir Adsorption isotherm. Potentiodynamic polarization measurements showed that Pheniramine is mixed-type inhibitor. Further, theoretical calculations were carried out and relations between computed parameters and experimental inhibition efficiency were discussed.
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effect of 2 2 benzothiazolyl disulfide on the corrosion of mild steel in acid media
Corrosion Science, 2009Co-Authors: Ashish Kumar Singh, Mumtaz A. QuraishiAbstract:Abstract 2,2′ benzothiazolyl disulfide (BTDS) has been synthesised and their inhibiting action on mild steel corrosion in 1 M HCl and 0.5 M H 2 SO 4 at 308 K has been investigated using weight loss, EIS, polarization and SEM study. BTDS showed better efficiency in 0.5 M H 2 SO 4 compared to 1 M HCl. Polarization studies revealed that BTDS is a mixed type inhibitor in both acids predominantly cathodic in 1 M HCl where as predominantly anodic in 0.5 M H 2 SO 4 . Thermodynamic parameters i.e. free energy of Adsorption, Enthalpy, entropy and activation energy were calculated, the values of these parameters showed good interaction.
Gino V Baron - One of the best experts on this subject based on the ideXlab platform.
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understanding hydrocarbon Adsorption in the uio 66 metal organic framework separation of un saturated linear branched cyclic adsorbates including stereoisomers
Journal of Physical Chemistry C, 2013Co-Authors: Tim Duerinck, Gino V Baron, Rocio Buenoperez, Frederik Vermoortele, Dirk De Vos, Sofia Calero, Joeri F M DenayerAbstract:The low coverage Adsorption properties of alkanes, alkenes, and aromatics of the linear, branched, and cyclic type (ca. 70 molecules) were studied using inverse pulse gas chromatography at zero coverage on the zirconium metal–organic framework UiO-66 and its functionalized analogues UiO-66-Me, UiO-66-NO2, UiO-66-Me2 in the temperature range 433–573 K. In our study, we determined and analyzed the Adsorption Enthalpy, Henry constants, and entropic factors. Preferential Adsorption of bulky molecules is observed with specific adsorbate and cage size effects, yielding very specific, preferential Adsorption. Remarkably high Adsorption selectivity factors (up to 14) for cyclo- compared to n-alkanes were found. The presence of additional groups (methyl, nitro) on the linkers in the framework influences Adsorption properties significantly, mainly by reducing the effective pore size. Whereas increased selectivity is observed for UiO-66-Me, this effect decreases again upon addition of a second methyl group, UiO-66-M...
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low coverage Adsorption properties of the metal organic framework mil 47 studied by pulse chromatography and monte carlo simulations
Physical Chemistry Chemical Physics, 2009Co-Authors: Vincent Finsy, Gino V Baron, Dirk De Vos, Sofia Calero, Elena Garciaperez, Patrick J Merkling, Gill Vedts, Joeri F M DenayerAbstract:Low-coverage Adsorption properties of the metal–organic framework MIL-47 were determined by a combined experimental and simulation study. Henry constants and low coverage Adsorption enthalpies of C5–C8 linear and branched alkanes, cyclohexane and benzene were measured from 120 to 240 °C using pulse gas chromatography. An adapted force field for linear and branched alkanes in MIL-47 was used to compute the Adsorption properties of those molecules. A new set of charges was developed for simulations with benzene in MIL-47. The Adsorption Enthalpy of linear alkanes increases with about 7.6 kJ mol−1 per additional –CH2– group. Henry Adsorption constants of iso-alkanes are slightly lower than those of the linear chains but the MIL-47 framework is not imposing steric constraints on the branched chains. Benzene and cyclohexane are adsorbed less strongly than n-hexane as they have less hydrogen atoms. For the studied non-polar molecules, the Adsorption energies are dominated by van der Waals interactions and benzene Adsorption is additionally influenced by Coulombic interactions. The simulated tendencies are in good agreement with the experiments.
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investigation of inverse shape selectivity in alkane Adsorption on sapo 5 zeolite using the tracer chromatography technique
Journal of Catalysis, 2004Co-Authors: Johan A Martens, Joeri F M Denayer, Ahmet Ocakoglu, Gino V BaronAbstract:Abstract Adsorption of linear and branched alkanes (C4–C8 range) on a microporous silicoaluminophosphate material (SAPO-5) was studied using the chromatographic technique at 353–573 K. Under these experimental conditions of low micropore occupancy specific branched molecules adsorb preferentially over the corresponding linear isomers. Such inverse shape selectivity was encountered with isobutane, isopentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, and 2,2-dimethylhexane. Other skeletal isomers exhibit the conventional shape selectivity; i.e., their Adsorption is less favorable compared to the linear alkane with the same carbon number. The occurrence of inverse shape selectivity versus conventional shape selectivity can be explained in terms of compensation between the Adsorption Enthalpy and entropy. The branched species that exhibit inverse shape selectivity have a higher Adsorption Enthalpy compared to the linear chains, counterbalancing the negative contribution of Adsorption entropy to the Adsorption equilibrium.
Philip L Llewellyn - One of the best experts on this subject based on the ideXlab platform.
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structural origin of unusual co2 Adsorption behavior of a small pore aluminum bisphosphonate mof
Journal of Physical Chemistry C, 2015Co-Authors: Philip L Llewellyn, Thomas Devic, Sandrine Bourrelly, Yaroslav Filinchuk, Miquel Garciarates, Lucia Gaberova, Stuart R Miller, Jeanclaude Lavalley, Emily Bloch, Paul A WrightAbstract:The Adsorption of CO2, CH4, and N2 at 303 K by MIL-91(Al), one of the few porous phosphonate-based-MOFs, has been investigated by combining advanced experimental and computational tools. Whereas CH4 and N2 Adsorption isotherms exhibit type I behavior, the reversible CO2 isotherm displays an unusual inflection point at low pressure. In situ X-ray powder diffraction and infrared spectroscopy showed structural changes of this small-pore MOF upon CO2 Adsorption. Grand canonical Monte Carlo simulations delivered a detailed picture of the Adsorption mechanisms at the microscopic level. The so-predicted arrangements of the confined CO2 molecules were supported by analysis of the in situ diffraction and infrared experiments. It was shown that while adsorbed CH4 and N2 are located mainly in the center of the pores, CO2 molecules interact with the hydrogen-bonded POH–N acid–base pairs. This results in a relatively high Adsorption Enthalpy for CO2 of ca. −40 kJ mol–1, which suggests that this material might be of in...
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how water fosters a remarkable 5 fold increase in low pressure co2 uptake within mesoporous mil 100 fe
Journal of the American Chemical Society, 2012Co-Authors: Estelle Soubeyrandlenoir, Christian Serre, Christelle Vagner, Ji Woong Yoon, Philippe Bazin, Florence Ragon, Young Kyu Hwang, Jongsan Chang, Philip L LlewellynAbstract:The uptake and Adsorption Enthalpy of carbon dioxide at 0.2 bar have been studied in three different topical porous MOF samples, HKUST-1, UiO-66(Zr), and MIL-100(Fe), after having been pre-equilibrated under different relative humidities (3, 10, 20, 40%) of water vapor. If in the case of microporous UiO-66, CO2 uptake remained similar whatever the relative humidity, and correlations were difficult for microporous HKUST-1 due to its relative instability toward water vapor. In the case of MIL-100(Fe), a remarkable 5-fold increase in CO2 uptake was observed with increasing RH, up to 105 mg g–1 CO2 at 40% RH, in parallel with a large decrease in Enthalpy measured. Cycling measurements show slight differences for the initial three cycles and complete reversibility with further cycles. These results suggest an enhanced solubility of CO2 in the water-filled mesopores of MIL-100(Fe).
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functionalizing porous zirconium terephthalate uio 66 zr for natural gas upgrading a computational exploration
Chemical Communications, 2011Co-Authors: Philip L Llewellyn, Qingyuan Yang, Andrew D Wiersum, Vincent Guillerm, Christian Serre, Guillaume MaurinAbstract:The ligand functionalization effect on the CO2/CH4 separation performance of the MOF type UiO-66(Zr) was explored computationally. The –SO3H and –CO2H functionalized forms show the highest selectivity, good working capacity and medium ranged CO2 Adsorption Enthalpy that make these materials very promising for physisorption-based processes.
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prediction of the conditions for breathing of metal organic framework materials using a combination of x ray powder diffraction microcalorimetry and molecular simulation
Journal of the American Chemical Society, 2008Co-Authors: Philip L Llewellyn, Christian Serre, Guillaume Maurin, Thomas Devic, Sandra Loeraserna, Nilton Rosenbach, Sandrine Bourrelly, Patricia Horcajada, Yaroslav Filinchuk, Gerard FereyAbstract:The Adsorption of C1 to C4 linear hydrocarbons in the flexible metal organic framework MIL-53(Cr) has been followed by Adsorption manometry coupled with microcalorimetry and Synchrotron X-ray powder diffraction. This experimental investigation was completed by molecular modeling. In the case of methane, the solid remains rigid whatever the adsorbate amount. However for the C2−C4 series, an increasing flexibility of the structure is observed, which is ascribed first to a breathing of the material from a large pore to a narrow pore form followed by a further expansion at high pressure. The collected thermodynamic and structural information suggests that a minimum Adsorption Enthalpy of ca. 20 kJ mol−1 in the initial large pore structure of MIL-53(Cr) is required to induce the structural transition “large to narrow pore”. Further, the Enthalpy of Adsorption can be used to predict the pressure at which the structure reopens. Finally, the magnitude of the breathing can be related to the size of the probe molec...