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1.
Hydrogen adsorption on activated carbons was investigated in the present works up to 100 bars at 298 K. Coconut-shell was activated by potassium hydroxide, resulting in activated carbons with different porosities. All of prepared activated carbons are microporous and show the same adsorption properties. The complete reversibility and fast kinetics of hydrogen adsorption show that most of adsorbed quantity is due to physical adsorption. A linear relationship between hydrogen adsorption capacity and pressure is obtained for the all samples regardless of their porosities. Hydrogen adsorption capacities are linear function of porosities such as specific surface area, micropore surface area, total pore volume, and micropore volume. The maximum hydrogen adsorption capacity of 0.85 wt.% at 100 bars, 298 K is obtained in these materials. 相似文献
2.
Variable-temperature infrared spectroscopy was used for a thermodynamic study on hydrogen adsorption on the zeolite Ca-Y. Adsorption renders the H–H stretching mode infrared active, at 4078 cm −1; and simultaneous measurement of IR absorbance and hydrogen equilibrium pressure, over a range of temperature, allowed standard adsorption enthalpy and entropy to be determined. They resulted to be Δ H°= −15.0(±1.0) kJ mol −1 and Δ S° = −127(±10) J mol −1 K −1, respectively. These relatively high values of adsorption enthalpy and entropy are discussed in the broader context of corresponding data for other hydrogen adsorbents. 相似文献
3.
The demand for fast screening methods in modern materials chemistry led to the development of a room temperature operated high-throughput tool for adsorption screening. Within five minutes a porosity screening of a large sample pool can be realized. Using a variety of different porous materials (activated carbons, porous polymers, metal-organic frameworks, zeolites) and the test gas n-butane, the reliability of the new instrument is shown. Furthermore, possible applications in the determination of n-butane capacities and BET surface areas are given as well as the application in synthesis or product control.The presented data exhibit high quality factors for the correlation of integrated signal intensity (heat of adsorption) and specific surface areas (above 0.97). As an example for the applicability of other gases that can be used with this tool, screening measurements using cyclohexane as test gas are also presented. The developed automated screening tool is an important step to overcome the bottle-neck between high-throughput syntheses technologies developed in the last decades and measurement of adsorption properties. 相似文献
4.
In this work, we calculate the adsorption isotherms and isosteric heat of argon in molecular models of saccharose coke obtained via the Hybrid Reverse Monte Carlo method. In the first route (method A), the molecular models were built by considering only carbon atoms, and all other heteroatoms present were neglected. In the second route (method B), the molecular models were built by considering carbon and hydrogen atoms. We find that the models obtained via method B have smaller pores as compared to the models obtained via method A. This is reflected in the adsorption properties. The amount adsorbed is less in models obtained via method B as compared to method A. We also find that the isosteric heat calculated in the models obtained via method B match the experimental data more closely as compared to models obtained from method A. 相似文献
6.
采用天然钙基蒙脱土为原料,经碳酸钠钠化处理后,分别用十六烷基三甲基溴化铵和十八烷基三甲基氯化胺进行有机化改性,然后将两种有机土分别与不同的中性胺(八烷胺、十烷胺和十二胺)以及正硅酸乙酯按一定的摩尔比混合反应制备蒙脱土多孔异构材料.利用X射线衍射探讨了不同改性土层间距变化情况,同时考察了不同有机土和中性胺以及反应物摩尔配比和反应时间等因素对合成蒙脱土多孔异构材料的影响. 相似文献
7.
Phenol physisorption on a series of porous and non-porous amorphous carbons was studied at 298 K. Grand Canonical Monte Carlo computer simulations were performed to simulate phenol adsorption from the gas phase. Phenol is adsorbed in a solid-like state within the pores and there is no well-developed multilayer regime. The ‘ t’ plot method was adapted to phenol adsorption and the results obtained are in agreement with the model solids employed. The simulated adsorption isotherms were compared with experimental results obtained for adsorption from aqueous solutions of phenol. BET surface areas were calculated. Other characteristics of the adsorption system analyzed were: adsorption energy distribution functions, density profiles, distribution of molecules according to gas-solid energy, and local isotherms. 相似文献
8.
Highly ordered porous carbon materials obtained by a replica technique have been used for supercapacitor application and electrochemical hydrogen storage. For the preparation of the well-tailored carbons, MCM-48, SBA-15 and MSU-1 molecular sieves served as templates, whereas a sucrose solution, propylene and pitch were the carbon source. A careful physico-chemical characterization (CO 2 and N 2 adsorption, X-ray diffraction, electron microscopy observations) allowed to estimate the total surface area, the pore size distribution, the micro/mesopore volume as well as the structure and the microtexture of the investigated carbons. The specific capacitance (F/g) and the hydrogen adsorption capacity in the carbon nanopores were correlated with the microtextural properties. Especially, a linear dependence has been found between the capacitance or the amount of electrochemically stored hydrogen and the ultramicropores (pores smaller than 0.7 nm) volume. It clearly indicates that in these carbons: (a) the major part of the electrical double layer is charged with non-solvated ions; (b) ultramicropores play a determinant role for hydrogen storage. 相似文献
9.
The removal of low concentrations of hydrogen sulfide by adsorption and catalytic combustion has been studied. Concentration of hydrogen sulfide by adsorption from waste-gas streams is best effected by molecular sieve 13X, if the stream is dry, and by activated carbon, if the gas stream is moist. Low-temperature catalytic oxidation of hydrogen sulphide in moist gas streams can be effected over activated carbon. The reaction appears to involve ionized hydrogen sulfide, dissolved in water condensed in the pores of the carbon. At high temperatures, both supported platinum and palladium catalysts are found to be oxidation catalysts. Palladium is the best catalyst for methane oxidation but is partially deactivated in the presence of sulfur-containing gases. In contrast, platinum was more active for the same reaction in the presence of sulfur-containing gases. Both metals were found to promote the oxidation of hydrogen sulfide above ca. 150°C. The power rate laws describing the kinetics of reaction were determined. 相似文献
10.
A typical relation between accumulated liquid, temperature, and vapour pressure characterizes any surface, in particular any
porous structure. This relationship is usually described by means of “adsorption isotherms”, which are functions that correlate
the amount of liquid in the porous material to the partial pressure of its vapour, for a given constant temperature. Speaking
about fibrous insulation materials or building materials, the fluid of interest is simply water. The knowledge of water adsorption
isotherms is of great importance in the formulation of heat and mass transfer models inside moist bodies. Typical experimental
techniques for adsorption isotherm evaluation (salt solution methods, climatic chamber methods, etc.) require the conteporary
control of both temperature and relative humidity of the environment surrounding the specimen. This often results in the need
of dedicated and expensive experimental set-ups. In this work the possibility to use a simpler apparatus to obtain the sorption-desorption
characteristics of a body is investigated from the theoretical point of view by means of simulated experiments. The proposed
measurement procedure uses a closed, non permeable system in which only temperature is to be controlled, while the total water
content, liquid plus vapor, remains constant. The new procedure offers an additional benefit, since both the constant water
and the constant dry air mass constraints are used as further a␣priori information to improve the precision of the estimated
results. 相似文献
11.
计算化学方法在多孔储氢材料的应用主要有4个方面:1)研究多孔材料的储氢性能;2)研究多孔材料对氢气的吸附热;3)研究储氢机理;4)设计新型多孔储氢材料。综述了计算化学方法在多孔储氢材料研究中取得的成果和最新进展,展望了计算化学方法在储氢领域的应用前景。 相似文献
12.
ABSTRACTThis review is focused on the rapidly expanding field of porous materials for the sensor, actuator, energy storage and energy generation application. The synthesis methods to produce excellent porous composites and designs required for the domestic applications are also discussed. The properties of the porous composite materials are characterized and compared with non-porous polymer composite materials. In addition, porous materials based on polymer blends and their controllable synthesis methods for adjusting anticipated properties are highlighted. The properties, processing methods, applications, limitations, challenges and promising directions of porous composite materials for imminent advancement in this field are discussed. 相似文献
13.
Hydrogen storage is a crucially missing link to a future “hydrogen economy.” Extensive hydrogen storage studies have been focused on carbon-based adsorbents due to their light weight, high surface area, and tailorable structure. An overview/analysis of the progress on hydrogen storage on various carbon-based adsorbents is given in this review. Particularly, a recent, fast-developing research direction—hydrogen storage via spillover on carbons via added catalysts — is reviewed separately. A fundamental understanding of the factors that affect both H 2 and spillover hydrogen storage capacities, as well as strategies for improving the storage performance from the viewpoints of both hydrogen storage and materials chemistry, are discussed. 相似文献
14.
This research investigates the adsorption properties of three activated carbons (AC) derived from coconut, coal, and wood
origin. A linear relationship exists between the number of water molecules adsorbed onto each AC and the oxygen content determined
elemental analysis and XPS. An inverse linear relationship exists between the plateau amount of dodecanoic acid anionic surfactant
and the oxygen content on the surface of ACs. The surface charge on each AC’s surface had a linear relationship with the plateau
amount of dodecanoic acid. A plug-flow heterogeneous surface diffusion model (PFHSDM) for a fixed-bed adsorption process was
developed to describe the adsorption kinetics in a fixed-bed column. The model represents axially dispersed plug-flow, external
mass transfer, adsorption equilibrium on the fluid-particle interface, and intraparticle diffusion. The larger molecular dimension
of the dodecanoic acid as a more hydrophobic entity than octanoic acid led to a faster external mass transfer rate but a slower
surface diffusion rate as estimated from the PFHSDM. The interaction between the organic moiety of surfactant and the AC surface
chemistry such as surface oxygen content and surface charge contributes to the adsorption performance in both to the adsorption
equilibrium and kinetics. 相似文献
15.
本文在叙述了氢气的来源和传统的分离与纯化技术的基础上,论述了 PSA 法Prism 法、低温法、金属氢化物法等在氢气的分离与纯化方面的开发现状、工艺过程、分离原理及其发展前景。 相似文献
16.
Porous polyimides are important class of macromolecules owing to their excellent redox behaviour, efficient capture of CO 2 and H 2 gases, interesting photocatalytic properties and superior thermal and chemical stabilities. Here we describe in detail, the synthesis and gas storage properties of a series of porous polyimides ( Tr-NPI, Tr-PPI, Tr-CPI, Td-PPI and Td-CPI) with various network topologies derived from polycyclic aromatic hydrocarbon linkers. These polyimides are synthesized in a single step by the condensation of corresponding polycyclic aromatic dianhydrides ( NDA, PDA and CDA) with structure directing amine ( TAPA and TAPM) monomers, having trigonal and tetrahedral geometry. The structure of all the polymers was fully characterized by various techniques. The present work also introduces for the first time porous polyimides containing rigid polycyclic aromatic compounds such as coronene. All the polyimides presented here exhibit high thermal stability and show selectivity towards CO 2 uptake at room temperature (293 K), due to the presence of aromatic clouds and CO 2 phillic oxygen and nitrogen functionalities on their pore surface. Moreover these polymers also showed significant uptake of H 2 gas (77 K). The present work has significant implications on the design of robust porous organic solids from small molecules for efficient capture of CO 2 and H 2 gases. 相似文献
17.
In the framework of the EC project STORHY (Hydrogen Storage for Automotive Applications), the prototype of a solid storage tank for hydrogen based on sodium alanate was developed. A storage tank containing 8 kg sodium alanate was designed and manufactured with the objective of fast refueling. To obtain the optimum design of the storage tank a simulation tool was developed and validated by experiments with a laboratory‐scale tubular reactor. Application of the simulation tool to different storage concepts and geometries yielded the final design. The chosen concept is modular, enabling simple scale‐up. This is the basis for the future development of fuel cell vehicle storage tanks containing 5 kg of hydrogen. 相似文献
18.
ABSTRACTMetal organic frameworks (MOFs) have become material of special attention due to their high porosity and large surface area. Adsorptive removal of ciprofloxacin hydrochloride using MOFs from aqueous waste and real wastewater has been studied in this work. The MOF-5 synthesized showed higher adsorption capacity as compared to activated charcoal. The adsorption satisfies the pseudo-second-order kinetic model and adsorption isotherm is very well explained by the Freundlich and the Sips isotherm. The adsorption mechanism may be explained by the electrostatic interactions of the pharmaceutical compounds and the MOF-5 surface. Finally, it can be concluded that MOF-5 has shown a great potential for their application in wastewater treatment technology development. 相似文献
19.
Hydrotalcite was synthesized by co-precipitation using metal nitrate precursor and potassium carbonate with Mg:Al ratio of 3:1. The samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) and nitrogen adsorption/desorption. The surface morphology and chemical composition were characterized by scanning electron microscope (SEM) and energy dispersive X-ray (EDX). Characterization of hydrotalcite reveals that hydrotalcite prepared in this work exhibited a type II isotherm which is typical of mesoporous and slit shape pore materials. The hydrotalcite structures demonstrated higher degree of crystallinity when thermally treated at 700 °C. Carbon dioxide adsorption was conducted using adsorption unit and the result showed an increase of CO2 adsorption when hydrotalcite was coated on commercial zeolites. 相似文献
20.
This paper presents an overview of the results of our research group in methane storage, in which the behaviour of different carbon materials in methane storage has been studied. These materials include physically activated carbon fibres (ACFs), chemically activated carbons (ACs) and activated carbon monoliths (ACMs), all of them prepared in our laboratories. These results have been compared with those corresponding to commercial ACFs, commercial activated carbon cloths and felts, and a commercial activated carbon.An in depth analysis (different raw materials, activating agent and preparation variables) has been done in order to obtain the carbon material with the best methane adsorption capacity by unit volume of adsorbent. The important effect of the micropore volume, micropore size distribution (MPSD) and packing density of the carbon materials in the methane adsorption capacity and delivery has been analysed. After this study, activated carbons with volumetric methane uptake as high as 166 v/v and delivery of 145 v/v have been prepared. In addition, ACM with methane uptake of 140 v/v and a delivery of 126 v/v has also been obtained.Moreover, the results corresponding to preliminary in situ small angle neutron scattering (SANS) study of CD 4 adsorption under pressure in different porous carbons and a zeolite are also included. These experiments have established SANS as a viable technique to investigate high-pressure methane adsorption. CD 4 adsorption at supercritical conditions produces changes in the SANS curves. The changes observed are in agreement with theoretical speculations that the density of the adsorbed phase depends upon the pore size. 相似文献
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