共查询到20条相似文献,搜索用时 15 毫秒
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R. Roque-Malherbe C. Lozano F. Marquez A. Hernandez-Maldonado 《Journal of solid state chemistry》2011,184(5):1236-15569
A careful structural characterization was carried out to unequivocally determine the structure of the synthesized material. The TGA, DRIFTS and a Pawley fitting of the XRD powder profiles indicate that the hydrated and in situ dehydrated polymorph crystallizes in the orthorhombic space group Pnma. Meanwhile, the CO2 isosteric heat of adsorption appears to be independent of loading with an average value of 30 kJ/mol. This translates to a physisorption type interaction, where the adsorption energy corresponding to wall and lateral interactions are mutually compensated to produce, an apparently, homogeneous adsorption energy. The somewhat high adsorption energy is probably due to the confinement of the CO2 molecules in the nitroprusside pores. Statistical Physics and the Dubinin theory for pore volume filling allowed model the CO2 equilibrium adsorption process in Cu-nitroprusside. A DRIFTS test for the adsorbed CO2 displayed a peak at about 2338 cm−1 that was assigned to a contribution due to physical adsorption of the molecule. Another peak found at 2362 cm−1 evidenced that this molecule interacts with the Cu2+, which appears to act as an electron accepting Lewis acid site. The aim of the present paper is to report a Pnma stable Cu-nitroprusside polymorph obtained by the precipitation method that can adsorb carbon dioxide. 相似文献
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The adsorption of CO2 on a number of activated carbons, thermal carbon black, and oxide materials at 195 K was studied using static and dynamic
techniques. The landing surface areas ω(CO2) ≈ 0.19 nm2 on thermal carbon black and the absolute values of sorption for P/P
0 < 0.4 were determined. The density of adsorbed CO2 in the micropore volume was estimated at ρ(CO2) = 0.91 g/cm3. It was demonstrated that the previously found effect of a weakening of the sorption interaction of nitrogen molecules with
thin-walled materials (which manifested itself in an analysis of sorption isotherms by a comparative method) was pronounced
to a lesser degree for the sorption of CO2. At the same time, the presence of supermicropores in activated carbon samples resulted in overestimated values of surface
areas. A dynamic method was proposed to measure the spectra of CO2 desorption at 195–260 K using a SORBI-MS system for evaluating the binding energy of sorbate molecules with the surface. 相似文献
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Predicting solute adsorption on activated carbon: phenol 总被引:2,自引:0,他引:2
Activated carbon (AC), the most widely used adsorbent in water and in wastewater treatment, comprises a high surface area of very small, convoluted and interconnected pores. Despite the wide use of AC, there is little fundamental atomic-level understanding of its adsorption capacity and selectivity as well as its pore structure. The purpose of this work is to suggest the methodology for calculation of equilibrium adsorption capacity of common water organic pollutants and use it for phenol as a model. The effects of various functional groups, pore size, and coverage on thermodynamics of phenol adsorption from the gas phase and from water media are calculated using molecular mechanics (MM) and density functional theory (DFT) approaches. 相似文献
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V. Yu. Yakovlev A. A. Fomkin A. V. Tvardovskii V. A. Sinitsyn 《Russian Chemical Bulletin》2005,54(6):1373-1377
Adsorption isotherms of carbon dioxide on the microporous ACC carbon adsorbent and the adsorption deformation of the adsorbent
were measured. The heats of adsorption at temperatures raising from 243 to 393 K and pressures from 1 to 5⋅106 Pa were measured. In the low-temperature region (243 K), an increase in the amount adsorbed is accompanied by adsorbent contraction,
and at high micropore fillings (a > 10 mmol g−1) the ACC carbon adsorbent expands. At high temperatures, adsorbent expansion is observed in the whole region of micropore
filling. At 243 K in the low filling region (a < 1 mmol g−1), the heat of adsorption decreases smoothly from 27 to 24 kJ mol−1. The heat of adsorption remains virtually unchanged in the interval 2 mmol g−1 < a < 11 mmol g−1 and then decreases to 8 kJ mol−1 at a = 12 mmol g−1. Taking into account the nonideal character of the gas phase and adsorbent deformation the heats of adsorption are strongly
temperature-dependent in a region of high pressures.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1331–1335, June, 2005. 相似文献
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Liquid phase hydrogenation of phenol over Pt/C catalysts was investigated under conventional conditions and supercritical carbon dioxide (scCO2). The equivalent ration of hydrogen to phenol shows a significant effect on the product selectivity. Hydrogenation of phenol in different solvents was also studied, the experimental results show that polarity of solvents influences the yield of cyclohexanone remarkably, scCO2 has the highest one. Catalytic hydrogenation of phenol in scCO2 or sub-scCO2 was emphatically researched. The result is that near the critical point of CO2 phenol has higher reaction activity than that of normal organic solvents, cyclohexanone has 47% in yield and 87% in selectivity. 相似文献
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Dominika Bukalak Izabela Majchrzak-Kucęba Wojciech Nowak 《Journal of Thermal Analysis and Calorimetry》2013,113(1):157-160
Adsorption methods using solid sorbents are an alternative to the absorption technology in the processes of purification gases from carbon dioxide. There is a need to rapidly assess the suitability of sorbents for use it in PSA, TSA, or VPSA installations. Important parameters which determine the quality of the sorbent are the sorption capacity of sorbent, selectivity to CO2 and the possibility of regeneration. This paper presents the results of sorption/desorption of CO2 study on the impregnated porous materials using thermogravimetric methods. Thermogravimetry allows for rapid assessment of sorption capacity and regeneration of the sorbents. Specially selected temperature program allowed to determine the sorption capacity of sorbents depending on the concentration of CO2 in the gas mixture and temperature. Degree of sorbent purification was determined in desorption process. 相似文献
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A charcoal-supported rhodium catalyst was highly active for the ring hydrogenation of phenol and cresols under supercritical carbon dioxide. 相似文献
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L. A. Zemskova A. V. Voit N. N. Barinov Yu. M. Nikolenko D. Kh. Shlyk 《Russian Journal of Inorganic Chemistry》2016,61(12):1567-1572
Manganese oxides have been prepared on the surface of carbon fiber by simple methods: coprecipitation of manganese salts of different valence in the presence of fiber as a support or electrodeposition from Mn(II) salt solution on a carbon fiber cathode, in the presence of chitosan including, under oxidation with air oxygen conditions. The obtained samples have been characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Sorption properties of the composites toward As(V) have been studied. The relationships between sorption properties, structure, Mn valence, and manganese oxide surface morphology have been discussed. 相似文献
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José A. Delgado María A. Uguina José L. Sotelo Beatriz Ruíz Marcio Rosário 《Adsorption》2007,13(3-4):373-383
In this work, the separation of carbon dioxide/methane mixtures by PSA using a basic resin (Amberlite IRA-900) has been studied.
Adsorption equilibrium and kinetics of carbon dioxide and methane on a fixed-bed of this adsorbent have been measured, and
a binary adsorption equilibrium isotherm has been obtained. The adsorbent deactivation with the number of adsorption-desorption
cycles, and its regeneration, have also been analysed. A model based on the LDF approximation has been used to describe the
experimental breakthrough curves. The applicability of the basic resin to the separation of carbon dioxide/methane mixtures
has been studied in an experimental PSA setup using a single bed. The validity of the model used in the fixed-bed study for
simulating a PSA system has been checked by comparing the simulated and the experimental performance of the proposed PSA cycle. 相似文献
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Dawson R Stevens LA Drage TC Snape CE Smith MW Adams DJ Cooper AI 《Journal of the American Chemical Society》2012,134(26):10741-10744
Alcohol-containing polymer networks synthesized by Friedel-Crafts alkylation have surface areas of up to 1015 m(2)/g. Both racemic and chiral microporous binaphthol (BINOL) networks can be produced by a simple, one-step route. The BINOL networks show higher CO(2) capture capacities than their naphthol counterparts under idealized, dry conditions. In the presence of water vapor, however, these BINOL networks adsorb less CO(2) than more hydrophobic analogues, suggesting that idealized measurements may give a poor indication of performance under more realistic carbon capture conditions. 相似文献
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M. Kh. Annagiev Dzh. T. Rustamova S. S. Bairamova 《Russian Journal of Applied Chemistry》2012,85(4):684-685
Analcime samples were studied with the aim of cleaning air from phenol. 相似文献
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Carbon monoxide adsorbed on MgO is strongly trapped by the adsorbed carbon dioxide, increasing the heat of adsorption from 85.4 to 184.1 kJ/mol. The trapped CO is thought to be captured by two or three adsorbed CO2 and becomes less active to react with oxygen.
, MgO, , 85,4 184,1 /. , CO CO2 .相似文献
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Due to interaction with carbon dioxide, when some adsorbed oxygen atoms on silver surfaces are converted into carbonate groups, the binding energy diminishes and the volatility of adsorbed oxygen rises.
, , .相似文献
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The removal of phenol and related compounds from dilute aqueous solutions by activated carbons corresponds to the coating of the micropore walls and of the external surface by a monolayer. This process is described by an analog of the Dubinin—Radushkevich—Kaganer equation. On the other hand, as suggested by immersion calorimetry at 293 K, in the case of concentrated solutions, the mechanism corresponds to the volume filling of the micropores, as observed for the adsorption of phenol from the vapor phase. The equilibrium is described by the Dubinin—Astakhov equation. It follows that the removal of phenol from mixtures with water depends on the relative concentrations, and the limiting factor for adsorption is either the effective surface area of the carbon, or the micropore volume. 相似文献
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V. Kh. Fedotov N. I. Kol’tsov N. A. Gaidai Yu. A. Agafonov M. A. Botavina A. L. Lapidus 《Russian Journal of Applied Chemistry》2016,89(5):719-726
Results of nonstationary experiments on linear relaxation times were used to determine the rates of carbon dioxide adsorption and desorption on chromium oxide and gallium oxide catalysts by various mechanisms. The rate constants were used to calculate nonstationary concentrations of carbon dioxide on the assumption of linear, dissociative, and bimolecular adsorption–desorption mechanisms. A comparison of the calculated and experimental concentrations of carbon dioxide led to a conclusion that the process of its adsorption most probably occurs by the dissociative mechanism. 相似文献