The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
E. I. Terukov - One of the best experts on this subject based on the ideXlab platform.
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investigation of the structure elemental and phase compositions of fe3o4 sio2 composite layers by scanning electron microscopy x ray spectroscopy and thermal Nitrogen Desorption methods
Physics of the Solid State, 2014Co-Authors: V I Almyashev, K. G. Gareev, S. A. Ionin, V. S. Levitskii, V. A. Moshnikov, E. I. TerukovAbstract:The composite layers formed by drying a Fe3O4-SiO2-based colloidal solution were studied. The colloidal solution was obtained by the precipitation of Fe3O4 in the presence of highly dispersed silicon dioxide synthesized by the sol-gel method from a tetraethoxysilane alcohol solution. The microstructure and composition of the layers were analyzed using scanning electron microscopy, energy-dispersive X-ray microanalysis, thermal Nitrogen Desorption, and Raman spectroscopy. The emphasis was placed on the study of phase transitions in iron oxides under laser radiation. It was found that the tetraethoxysilane content has a substantial influence on the ratio of iron oxide and silicon dioxide in the layer, the specific surface area of SiO2 powders, the threshold laser radiation power necessary to induce the Fe3O4 α -Fe2O3 phase transformation, and on the position of the maximum of the absorption band corresponding to the A1g vibrations in α-Fe2O3.
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Investigation of the structure, elemental and phase compositions of Fe_3O_4-SiO_2 composite layers by scanning electron microscopy, X-ray spectroscopy, and thermal Nitrogen Desorption methods
Physics of the Solid State, 2014Co-Authors: V. I. Al’myashev, K. G. Gareev, S. A. Ionin, V. S. Levitskii, V. A. Moshnikov, E. I. TerukovAbstract:The composite layers formed by drying a Fe_3O_4-SiO_2-based colloidal solution were studied. The colloidal solution was obtained by the precipitation of Fe_3O_4 in the presence of highly dispersed silicon dioxide synthesized by the sol-gel method from a tetraethoxysilane alcohol solution. The microstructure and composition of the layers were analyzed using scanning electron microscopy, energy-dispersive X-ray microanalysis, thermal Nitrogen Desorption, and Raman spectroscopy. The emphasis was placed on the study of phase transitions in iron oxides under laser radiation. It was found that the tetraethoxysilane content has a substantial influence on the ratio of iron oxide and silicon dioxide in the layer, the specific surface area of SiO_2 powders, the threshold laser radiation power necessary to induce the Fe_3O_4 α -Fe_2O_3 phase transformation, and on the position of the maximum of the absorption band corresponding to the A _1 g vibrations in α-Fe_2O_3.
Shivaji Sircar - One of the best experts on this subject based on the ideXlab platform.
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efficiency of Nitrogen Desorption from lix zeolite by rapid oxygen purge in a pancake adsorber
Aiche Journal, 2013Co-Authors: Siew Wah Chai, Mayuresh V. Kothare, Shivaji SircarAbstract:Significance A nonequilibrium, nonisothermal, nonisobaric model was used for numerical simulation of the efficiency of N2 Desorption from a LiX zeolite column by rapid purge with O2 in a pancake adsorber. The key parameters included Desorption time, adsorbent particle size, and the adsorber length to diameter ratio. The efficiency was found to be a complex function of these variables.
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Numerical study of Nitrogen Desorption by rapid oxygen purge for a medical oxygen concentrator
Adsorption, 2012Co-Authors: Siew Wah Chai, Mayuresh V. Kothare, Shivaji SircarAbstract:Efficient Desorption of selectively adsorbed N_2 from air in a packed column of LiX zeolite by rapidly purging the adsorbent with an O_2 enriched gas is an important element of a rapid cyclic pressure swing adsorption (RPSA) process used in the design of many medical oxygen concentrators (MOC). The amount of O_2 purge gas used in the Desorption process is a sensitive variable in determining the overall separation performance of a MOC unit. Various resistances like (a) adsorption kinetics, (b) column pressure drop, (c) non-isothermal column operation, (d) gas phase mass and thermal axial dispersions, and (e) gas-solid heat transfer kinetics determine the amount of purge gas required for efficient Desorption of N_2. The impacts of these variables on the purge efficiency were numerically simulated using a detailed mathematical model of non-isothermal, non-isobaric, and non-equilibrium Desorption process in an adiabatic column. The purge gas quantity required for a specific Desorption duty (fraction of total N_2 removed from a column) is minimum when the process is carried out under ideal, hypothetical conditions (isothermal, isobaric, and governed by local thermodynamic equilibrium). All above-listed non-idealities (a–e) can increase the purge gas quantity, thereby, lowering the efficiency of the Desorption process compared to the ideal case. Items (a–c) are primarily responsible for inefficient Desorption by purge, while gas phase mass and thermal axial dispersions do not affect the purge efficiency under the conditions of operation used in this study. Smaller adsorbent particles can be used to reduce the negative effects of adsorption kinetics, especially for a fast Desorption process, but increased column pressure drop adds to purge inefficiency. A particle size range of ∼300–500 μm is found to require a minimum purge gas amount for a given Desorption duty. The purge gas requirement can be further reduced by employing a pancake column design (length to diameter ratio, L / D
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numerical study of Nitrogen Desorption by rapid oxygen purge for a medical oxygen concentrator
Adsorption-journal of The International Adsorption Society, 2012Co-Authors: Siew Wah Chai, Mayuresh V. Kothare, Shivaji SircarAbstract:Efficient Desorption of selectively adsorbed N2 from air in a packed column of LiX zeolite by rapidly purging the adsorbent with an O2 enriched gas is an important element of a rapid cyclic pressure swing adsorption (RPSA) process used in the design of many medical oxygen concentrators (MOC). The amount of O2 purge gas used in the Desorption process is a sensitive variable in determining the overall separation performance of a MOC unit. Various resistances like (a) adsorption kinetics, (b) column pressure drop, (c) non-isothermal column operation, (d) gas phase mass and thermal axial dispersions, and (e) gas-solid heat transfer kinetics determine the amount of purge gas required for efficient Desorption of N2. The impacts of these variables on the purge efficiency were numerically simulated using a detailed mathematical model of non-isothermal, non-isobaric, and non-equilibrium Desorption process in an adiabatic column.
Chinnakonda S Gopinath - One of the best experts on this subject based on the ideXlab platform.
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effect of coverage and temperature on the kinetics of Nitrogen Desorption from rh 111 surfaces
Journal of Chemical Physics, 2002Co-Authors: Francisco Zaera, Chinnakonda S GopinathAbstract:The kinetics of molecular Nitrogen Desorption from Rh(111) single-crystal surfaces covered with atomic Nitrogen were characterized by both isothermal and temperature-programmed experiments. A complex kinetic behavior was observed for this system not describable by typical Arrhenius expressions even if coverage-dependent activation energies are considered. In fact, the possibility of developing an analytical expression for those Desorption rates is voided by the fact that they depend not only on surface temperature and Nitrogen coverage but also on the mode of preparation of the system. Isotope labeling experiments support the idea of the formation of surface Nitrogen islands and of preferential recombination and Desorption at their edges. Coadsorbed oxygen, a typical by-product in NO reduction catalysis, behaves kinetically in a way similar to surface Nitrogen as far as N 2 Desorption is concerned. The recombination of two surface Nitrogen atoms is typically slower than the reaction between one Nitrogen and one adsorbed NO molecule, and therefore the catalytic reduction of NO most likely occurs via the latter pathway.
Vladimir P. Zhdanov - One of the best experts on this subject based on the ideXlab platform.
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Simulation of kinetics of Nitrogen Desorption from Rh(111)
Catalysis Letters, 1996Co-Authors: Vladimir P. ZhdanovAbstract:Associative Desorption of N atoms from the Rh(111) surface is simulated in the framework of the lattice-gas model. The Arrhenius parameters and nearest-neighbour lateral interaction employed to describe the measured thermal Desorption spectra are as follows:v=1013 s−1,Ed=40 kcal/mol, and e1=1.7 kcal/mol. The results obtained are used to clarify the role of Nitrogen Desorption in the NO + CO reaction on Rh(111) atT=400–700 K andPNO≈PCO≈0.01 atm.
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Simulation of kinetics of Nitrogen Desorption from Rh(111)
Catalysis Letters, 1996Co-Authors: Vladimir P. ZhdanovAbstract:Associative Desorption of N atoms from the Rh(111) surface is simulated in the framework of the lattice-gas model. The Arrhenius parameters and nearest-neighbour lateral interaction employed to describe the measured thermal Desorption spectra are as follows: v =10^13 s^−1, E _d=40 kcal/mol, and ε_1=1.7 kcal/mol. The results obtained are used to clarify the role of Nitrogen Desorption in the NO + CO reaction on Rh(111) at T =400–700 K and P _NO≈ P _CO≈0.01 atm.
Steven L Suib - One of the best experts on this subject based on the ideXlab platform.
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self assembly of microporous manganese oxide octahedral molecular sieve hexagonal flakes into mesoporous hollow nanospheres
Journal of the American Chemical Society, 2003Co-Authors: Jikang Yuan, Kate Laubernds, Qiuhua Zhang, Steven L SuibAbstract:Manganese oxide hollow nanospheres were prepared using a straightforward, template-free synthesis. The resulting material was mesoporous, crystalline, and of uniform diameter. The nanospheres were characterized by XRD, HR-SEM, and HR-TEM, and pore size distributions were calculated from Nitrogen Desorption. Unlike previous synthesis methods that use an inorganic template, this procedure requires no separation after synthesis to remove the template. The nanospheres are composed of hexagonal γ-manganese oxide flakes and are approximately 400 nm in diameter. γ-MnO2 is composed of a ramsdellite matrix (1 × 2 tunnels) with randomly distributed microdomains of pyrolusite (1 × 1 tunnels). These materials could have applications as cathodic battery materials, oxidation catalysts, catalyst supports, and adsorbents for pollutants.