The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
D. Bianchi - One of the best experts on this subject based on the ideXlab platform.
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Adsorption models and heat of adsorption of adsorbed ortho di-methyl benzene species on silica by using Temperature Programmed Adsorption Equilibrium methods
Applied Catalysis A : General, 2008Co-Authors: A. Hachimi, T. Chafik, D. BianchiAbstract:The adsorption of ortho dimethyl benzene (o-DMB) at different adsorption temperatures T-a (T-a > 300 K) on a SiO2 solid pretreated at 723 K is studied by the Temperature Programmed Adsorption Equilibrium methods developed previously. These methods provide the evolutions of the adsorption equilibrium coverage of the adsorbed species theta(e) (theta(e) < 0.7) with the adsorption temperature Ta in quasi Isobar conditions. These experimental curves theta(e) =f(T-a) are compared to theoretical curves associated to adsorption models developed with the statistical thermodynamics formalism. These models assume either localized or mobile adsorbed species without and with interactions. It is shown that the Langmuir model (localized species without interaction) provides theoretical Isobars overlapped with the experimental data for different adsorption pressures P-a considering a heat of adsorption of 61 kJ/mol consistent with the isosteric heat of adsorption. FTIR data show that the adsorption sites are mainly the free OH groups of SiO2 with a small contribution of superficial oxygen species. In line with the development of the experimental microkinetic approach of heterogeneous catalytic processes, and considering previous works dedicated to the adsorption of diatomic molecules such as CO, H-2, NO on metal supported particles and metal oxides, it is concluded that adsorption models assuming localized adsorbed species without (Langmuir model) and with (Temkin model) interactions provide robust mathematical expressions, for (a) the adsorption coefficient and (b) the adsorption equilibrium coverage theta(e) =f(T-a, P-a)(,) consistent with the experimental data for T-a > 300 K. (c) 2007 Elsevier B.V. All rights reserved.
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Adsorption models and heat of adsorption of adsorbed ortho di-methyl benzene species on silica by using Temperature Programmed Adsorption Equilibrium methods
Applied Catalysis A : General, 2008Co-Authors: A. Hachimi, T. Chafik, D. BianchiAbstract:The adsorption of ortho dimethyl benzene (o-DMB) at different adsorption temperatures T-a (T-a > 300 K) on a SiO2 solid pretreated at 723 K is studied by the Temperature Programmed Adsorption Equilibrium methods developed previously. These methods provide the evolutions of the adsorption equilibrium coverage of the adsorbed species theta(e) (theta(e) < 0.7) with the adsorption temperature Ta in quasi Isobar conditions. These experimental curves theta(e) =f(T-a) are compared to theoretical curves associated to adsorption models developed with the statistical thermodynamics formalism. These models assume either localized or mobile adsorbed species without and with interactions. It is shown that the Langmuir model (localized species without interaction) provides theoretical Isobars overlapped with the experimental data for different adsorption pressures P-a considering a heat of adsorption of 61 kJ/mol consistent with the isosteric heat of adsorption. FTIR data show that the adsorption sites are mainly the free OH groups of SiO2 with a small contribution of superficial oxygen species. In line with the development of the experimental microkinetic approach of heterogeneous catalytic processes, and considering previous works dedicated to the adsorption of diatomic molecules such as CO, H-2, NO on metal supported particles and metal oxides, it is concluded that adsorption models assuming localized adsorbed species without (Langmuir model) and with (Temkin model) interactions provide robust mathematical expressions, for (a) the adsorption coefficient and (b) the adsorption equilibrium coverage theta(e) =f(T-a, P-a)(,) consistent with the experimental data for T-a > 300 K. (c) 2007 Elsevier B.V. All rights reserved.
A. Hachimi - One of the best experts on this subject based on the ideXlab platform.
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Adsorption models and heat of adsorption of adsorbed ortho di-methyl benzene species on silica by using Temperature Programmed Adsorption Equilibrium methods
Applied Catalysis A : General, 2008Co-Authors: A. Hachimi, T. Chafik, D. BianchiAbstract:The adsorption of ortho dimethyl benzene (o-DMB) at different adsorption temperatures T-a (T-a > 300 K) on a SiO2 solid pretreated at 723 K is studied by the Temperature Programmed Adsorption Equilibrium methods developed previously. These methods provide the evolutions of the adsorption equilibrium coverage of the adsorbed species theta(e) (theta(e) < 0.7) with the adsorption temperature Ta in quasi Isobar conditions. These experimental curves theta(e) =f(T-a) are compared to theoretical curves associated to adsorption models developed with the statistical thermodynamics formalism. These models assume either localized or mobile adsorbed species without and with interactions. It is shown that the Langmuir model (localized species without interaction) provides theoretical Isobars overlapped with the experimental data for different adsorption pressures P-a considering a heat of adsorption of 61 kJ/mol consistent with the isosteric heat of adsorption. FTIR data show that the adsorption sites are mainly the free OH groups of SiO2 with a small contribution of superficial oxygen species. In line with the development of the experimental microkinetic approach of heterogeneous catalytic processes, and considering previous works dedicated to the adsorption of diatomic molecules such as CO, H-2, NO on metal supported particles and metal oxides, it is concluded that adsorption models assuming localized adsorbed species without (Langmuir model) and with (Temkin model) interactions provide robust mathematical expressions, for (a) the adsorption coefficient and (b) the adsorption equilibrium coverage theta(e) =f(T-a, P-a)(,) consistent with the experimental data for T-a > 300 K. (c) 2007 Elsevier B.V. All rights reserved.
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Adsorption models and heat of adsorption of adsorbed ortho di-methyl benzene species on silica by using Temperature Programmed Adsorption Equilibrium methods
Applied Catalysis A : General, 2008Co-Authors: A. Hachimi, T. Chafik, D. BianchiAbstract:The adsorption of ortho dimethyl benzene (o-DMB) at different adsorption temperatures T-a (T-a > 300 K) on a SiO2 solid pretreated at 723 K is studied by the Temperature Programmed Adsorption Equilibrium methods developed previously. These methods provide the evolutions of the adsorption equilibrium coverage of the adsorbed species theta(e) (theta(e) < 0.7) with the adsorption temperature Ta in quasi Isobar conditions. These experimental curves theta(e) =f(T-a) are compared to theoretical curves associated to adsorption models developed with the statistical thermodynamics formalism. These models assume either localized or mobile adsorbed species without and with interactions. It is shown that the Langmuir model (localized species without interaction) provides theoretical Isobars overlapped with the experimental data for different adsorption pressures P-a considering a heat of adsorption of 61 kJ/mol consistent with the isosteric heat of adsorption. FTIR data show that the adsorption sites are mainly the free OH groups of SiO2 with a small contribution of superficial oxygen species. In line with the development of the experimental microkinetic approach of heterogeneous catalytic processes, and considering previous works dedicated to the adsorption of diatomic molecules such as CO, H-2, NO on metal supported particles and metal oxides, it is concluded that adsorption models assuming localized adsorbed species without (Langmuir model) and with (Temkin model) interactions provide robust mathematical expressions, for (a) the adsorption coefficient and (b) the adsorption equilibrium coverage theta(e) =f(T-a, P-a)(,) consistent with the experimental data for T-a > 300 K. (c) 2007 Elsevier B.V. All rights reserved.
P U Sauer - One of the best experts on this subject based on the ideXlab platform.
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four nucleon system with δ Isobar excitation
Physics Letters B, 2008Co-Authors: A Deltuva, A C Fonseca, P U SauerAbstract:Abstract The four-nucleon bound state and scattering below three-body breakup threshold are described based on the realistic coupled-channel potential CD Bonn + Δ which allows the excitation of a single nucleon to a Δ Isobar. The Coulomb repulsion between protons is included. In the four-nucleon system the two-baryon coupled-channel potential yields effective two-, three- and four-nucleon forces, mediated by the Δ Isobar and consistent with each other and with the underlying two-nucleon force. The effect of the four-nucleon force on the studied observables is much smaller than the effect of the three-nucleon force. The inclusion of the Δ Isobar is unable to resolve the existing discrepancies with the experimental data.
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three body electrodisintegration of the three nucleon bound state with δ Isobar excitation processes below pion production threshold
Physical Review C, 2004Co-Authors: A Deltuva, L P Yuan, J Adam, P U SauerAbstract:Electron scattering from the three-nucleon bound state with two- and three-body disintegration is described. The description uses the purely nucleonic charge-dependent CD-Bonn potential and its coupled-channel extension CD-Bonn+{delta}. Exact solutions of three-particle equations are employed for the initial and final states of the reactions. The current has one-baryon and two-baryon contributions and couples nucleonic with {delta}-Isobar channels. {delta}-Isobar effects on the observables are isolated. The {delta}-Isobar excitation yields an effective three-nucleon force and effective two- and three-nucleon currents beside other {delta}-Isobar effects; they are mutually consistent.
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trinucleon photonuclear reactions withδ Isobar excitation processes below pion production threshold
Physical Review C, 2004Co-Authors: A Deltuva, L P Yuan, J Adam, A C Fonseca, P U SauerAbstract:Radiative nucleon-deuteron capture and two- and three-body photo disintegration of the three-nucleon bound state are described. The description uses the purely nucleonic charge-dependent CD-Bonn potential and its coupled-channel extension CD Bonn + $\Delta$. The $\Delta$-Isobar excitation yields an effective three-nucleon force and effective two- and three-nucleon currents besides other $\Delta$-Isobar effects; they are mutually consistent. Exact solutions of three-particle equations are employed for the initial and final states of the reactions. The current has one-baryon and two-baryon contributions and couples nucleonic with $\Delta$-Isobar channels. $\Delta$-Isobar effects on the observables are isolated. Shortcomings of the theoretical description are discussed and their consequence for the calculation of observables is estimated.
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trinucleon photo reactions with δ Isobar excitation radiative nucleon deuteron capture and two body photo disintegration of the three nucleon bound state
Few-body Systems, 2002Co-Authors: L P Yuan, P U Sauer, A C Fonseca, K Chmielewski, M Oelsner, J AdamAbstract:Radiative nucleon-deuteron capture and photo-disintegration of the three-nucleon bound state with two-body final states are described. The description uses nucleon degrees of freedom extended to include the excitation of a single nucleon to a Δ-Isobar. The baryonic interaction and the electromagnetic current couple nucleonic states and states with a Δ-Isobar. Exact solutions of three-particle scattering equations are employed for the initial or final states of the reactions. The current has one-baryon and two-baryon contributions in all considered multipoles. The role of the Δ-Isobar in the description of the considered photo-reactions is discussed and found to be moderate. The spin observables \(\) and \(\) at 90° lab scattering angle can be calculated model-independently from the E1 Siegert term in the long-wavelength limit.
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Nucleon-Deuteron Scattering with Δ-Isobar Excitation
Few-Body Problems in Physics ’99, 2000Co-Authors: K Chmielewski, S Nemoto, A C Fonseca, P U SauerAbstract:A coupled-channel formulation with Δ-Isobar excitation is used for the description of nucleon-deuteron scattering. The three-particle scattering equations are solved by a separable expansion of the two-baryon transition matrix. The effect of Δ-Isobar excitation on spin-averaged and spin-dependent cross sections is studied.
Yu. I. Aristov - One of the best experts on this subject based on the ideXlab platform.
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Modelling of Isobaric stages of adsorption cooling cycle: An optimal shape of adsorption Isobar
Applied Thermal Engineering, 2013Co-Authors: B. N. Okunev, A.p. Gromov, Yu. I. AristovAbstract:Abstract This paper addresses the effect of the adsorption Isobar shape on dynamics of the Isobaric stages of adsorption chillers which are considered as real alternative to common compression and absorption machines. We used a mathematical model of coupled heat and mass transfer in a spherical adsorbent grain that is in thermal contact with a metal plate subjected to a fast temperature jump/drop from 60 °C to 70 °C. Several model Isobars of water adsorption (stepwise, linear and exponential) are tested to elucidate the effect of the Isobar shape. Temporal evolution of radial profiles of the temperature, pressure and adsorbed water concentration inside the grain is calculated and analysed. In most cases, the calculated dependencies of the average water uptake/release can be satisfactorily described by an exponential function up to the dimensionless conversions of 0.7–0.8. The characteristic ad-/desorption time τ is found to be strongly dependent on the Isobar shape. Both adsorption and desorption processes are fastest for the step-like Isobar, with the step positioned at temperature as much different from the final temperature of the metal plate as possible, because in this case the driving force for ad-/desorption process is maximal. Appropriate recommendation on enhancing the adsorption chiller dynamics is made.
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kinetics of water adsorption desorption under Isobaric stages of adsorption heat transformers the effect of Isobar shape
International Journal of Heat and Mass Transfer, 2009Co-Authors: I.s. Glaznev, D.s. Ovoshchnikov, Yu. I. AristovAbstract:Effect of the shape of equilibrium adsorption Isobar on dynamics of water adsorption/desorption under Isobaric stages of a basic cycle of an adsorption heat transformer has been studied. Selective water sorbent SWS-1L (CaCl2 confined to mesoporous silica gel) was used for these tests as its water adsorption Isobars have segments with both convex and concave shapes. From these experiments the conclusion has been drawn that the dynamics of adsorption on a single adsorbent grain is closely linked with the shape (convex or concave) of the segment of water adsorption Isobar between initial and final temperatures of the Isobaric process. In particular, under the same boundary conditions desorption is faster than adsorption for a concave Isobar segment and vice versa for a convex one.
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Kinetics of water adsorption/desorption under Isobaric stages of adsorption heat transformers: The effect of Isobar shape
International Journal of Heat and Mass Transfer, 2008Co-Authors: I.s. Glaznev, D.s. Ovoshchnikov, Yu. I. AristovAbstract:Effect of the shape of equilibrium adsorption Isobar on dynamics of water adsorption/desorption under Isobaric stages of a basic cycle of an adsorption heat transformer has been studied. Selective water sorbent SWS-1L (CaCl2 confined to mesoporous silica gel) was used for these tests as its water adsorption Isobars have segments with both convex and concave shapes. From these experiments the conclusion has been drawn that the dynamics of adsorption on a single adsorbent grain is closely linked with the shape (convex or concave) of the segment of water adsorption Isobar between initial and final temperatures of the Isobaric process. In particular, under the same boundary conditions desorption is faster than adsorption for a concave Isobar segment and vice versa for a convex one.
T. Chafik - One of the best experts on this subject based on the ideXlab platform.
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Adsorption models and heat of adsorption of adsorbed ortho di-methyl benzene species on silica by using Temperature Programmed Adsorption Equilibrium methods
Applied Catalysis A : General, 2008Co-Authors: A. Hachimi, T. Chafik, D. BianchiAbstract:The adsorption of ortho dimethyl benzene (o-DMB) at different adsorption temperatures T-a (T-a > 300 K) on a SiO2 solid pretreated at 723 K is studied by the Temperature Programmed Adsorption Equilibrium methods developed previously. These methods provide the evolutions of the adsorption equilibrium coverage of the adsorbed species theta(e) (theta(e) < 0.7) with the adsorption temperature Ta in quasi Isobar conditions. These experimental curves theta(e) =f(T-a) are compared to theoretical curves associated to adsorption models developed with the statistical thermodynamics formalism. These models assume either localized or mobile adsorbed species without and with interactions. It is shown that the Langmuir model (localized species without interaction) provides theoretical Isobars overlapped with the experimental data for different adsorption pressures P-a considering a heat of adsorption of 61 kJ/mol consistent with the isosteric heat of adsorption. FTIR data show that the adsorption sites are mainly the free OH groups of SiO2 with a small contribution of superficial oxygen species. In line with the development of the experimental microkinetic approach of heterogeneous catalytic processes, and considering previous works dedicated to the adsorption of diatomic molecules such as CO, H-2, NO on metal supported particles and metal oxides, it is concluded that adsorption models assuming localized adsorbed species without (Langmuir model) and with (Temkin model) interactions provide robust mathematical expressions, for (a) the adsorption coefficient and (b) the adsorption equilibrium coverage theta(e) =f(T-a, P-a)(,) consistent with the experimental data for T-a > 300 K. (c) 2007 Elsevier B.V. All rights reserved.
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Adsorption models and heat of adsorption of adsorbed ortho di-methyl benzene species on silica by using Temperature Programmed Adsorption Equilibrium methods
Applied Catalysis A : General, 2008Co-Authors: A. Hachimi, T. Chafik, D. BianchiAbstract:The adsorption of ortho dimethyl benzene (o-DMB) at different adsorption temperatures T-a (T-a > 300 K) on a SiO2 solid pretreated at 723 K is studied by the Temperature Programmed Adsorption Equilibrium methods developed previously. These methods provide the evolutions of the adsorption equilibrium coverage of the adsorbed species theta(e) (theta(e) < 0.7) with the adsorption temperature Ta in quasi Isobar conditions. These experimental curves theta(e) =f(T-a) are compared to theoretical curves associated to adsorption models developed with the statistical thermodynamics formalism. These models assume either localized or mobile adsorbed species without and with interactions. It is shown that the Langmuir model (localized species without interaction) provides theoretical Isobars overlapped with the experimental data for different adsorption pressures P-a considering a heat of adsorption of 61 kJ/mol consistent with the isosteric heat of adsorption. FTIR data show that the adsorption sites are mainly the free OH groups of SiO2 with a small contribution of superficial oxygen species. In line with the development of the experimental microkinetic approach of heterogeneous catalytic processes, and considering previous works dedicated to the adsorption of diatomic molecules such as CO, H-2, NO on metal supported particles and metal oxides, it is concluded that adsorption models assuming localized adsorbed species without (Langmuir model) and with (Temkin model) interactions provide robust mathematical expressions, for (a) the adsorption coefficient and (b) the adsorption equilibrium coverage theta(e) =f(T-a, P-a)(,) consistent with the experimental data for T-a > 300 K. (c) 2007 Elsevier B.V. All rights reserved.
