排序方式: 共有48条查询结果,搜索用时 31 毫秒
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甲醇处理煤的微孔性质及反应性研究 总被引:2,自引:0,他引:2
在低于临界温度下,用甲醇处理了三种不同变质程度的煤,以研究其比表面积及微孔容积等表面特性的变化。结果表明,用甲醇处理后煤的微孔性质发生了较大变化,其变化的大小顺序是:沈北褐煤>大同烟煤>晋城无烟煤。随甲醇处理温度或干馏温度升高,煤及半焦的孔径均向小的方向偏移。煤的平均孔径为8.2—8.6A;半焦的平均孔径为6.3—7.5A。煤经甲醇处理后其半焦的反应性均比未处理的高。 相似文献
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M. Barczak 《Journal of Thermal Analysis and Calorimetry》2005,79(3):499-507
Summary The survey covers the methods of producing pores of nanometer width. Features of such nanomaterials differ remarkably from both that of nanoparticles and that of materials with pores in the micrometer range. 相似文献
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A general method for the investigation of adsorption kinetics of nonlinear,nonisothermal systems, based on frequency response analysis, ispresented. It is based on the definition of higher-order frequency response functions (FRFs) on the adsorber and on the particle level. FRFs on the adsorber level can be estimated from experimentally measuredadsorber FR and used to calculate FRFs on the particle level,which can be further used for model identification, by comparison withtheoretical particle FRFs. The general procedure for calculation of particle FRFs from those of adsorber is given. Also, the generalprocedure for theoretical derivation of particle FRFs is given andillustrated with an example of nonisothermal adsorption governed bymicropore diffusion and film resistance heat transfer, as well as theprocedure for calculating unmeasured adsorber FRFs, which isillustrated with an example of a batch adsorber with volume modulation. 相似文献
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A new apparatus for the measurement of equilibria and dynamics for gas-phase adsorption systems is utilized to examine the adsorption of carbon dioxide on BPL activated carbon. The apparatus has a flow-through configuration. For dynamics, with constant inlet flow, pressure within the adsorbent-containing section is varied sinusoidally, and the time-dependent outlet flow rate is measured to determine an amplitude ratio and phase lag. Studies are made of temperature effects and particle size effects. Results are compared with several mathematical models. Frequency response data show that the BPL system follows surface (or micropore) diffusion kinetics. The rate of adsorption for the activated carbon is found to be only weakly dependent on the bulk particle size. 相似文献
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The transport properties of fluid argon in micropores, i.e. diffusivity and viscosity, were studied by molecular dynamics simulations. The effects of pore width, temperature and density on diffusivity and viscosity were analyzed in micropores with pore widths from 0.8 to 4.0 nm. The results show that the diffusivity in micropores is much lower than the bulk diffusivity, and it decreases as the pore width decreases; but the viscosity in micropores is significantly larger than the bulk one, and it increases sharply in narrow micropores. The diffusivity in channel parallel direction is obviously larger than that in channel perpendicular direction. The temperature and density are important factors that obviously affect diffusivity and viscosity in micropores. 相似文献
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Three methods, the Horvath-Kawazoe (HK) method, the Jaroniec-Gadkare-Choma (JGC) one and the Density Functional Theory (DFT), have been applied in the characterization of the microporous structure of several activated carbons. The samples were all based on the same parent material, that was subjected to various oxidative treatments, using solutions of concentrated HNO3 at various temperatures (298, 333, 363 and reflux at 383 K during 3 hours) or solutions of H2O2 of various concentrations (1, 5 and 10 M). The nitrogen adsorption isotherms of the solids, were studied at 77 K and in the relative pressure range of 10–6 < p/p
0 < 0.99. Only the isotherm parts up to a relative pressure of 0.2 were taken into consideration for obtaining the micropore size distributions. The evaluation of the method suitability was based on how well each one describes the experimentally obtained data. The three methods describe satisfactorily the experimental results, including the transitions of the isotherms related to the stages of micropore filling. The effects of the oxidative treatment on the structure of the solids, as judged from their micropore size distributions, are also discussed. 相似文献
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Roman Wojsz Michał Rozwadowski 《Journal of inclusion phenomena and macrocyclic chemistry》1987,5(6):759-765
The applicability of earlier derived equations for adsorption isotherms for the determination of differential curves characterizing the approximate distribution of micropore volumes in relation to their radii is studied. It is concluded that besides the Gaussian distribution, the Rayleigh and exponential distributions also possess a physical sense. 相似文献
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活性炭吸附CO2与其微孔体积的关系 总被引:5,自引:1,他引:4
对五种活性炭样品进行液氮温度下的N2吸附、碘吸附测定和冰点下的CO2吸附表征。结果表明,碘吸附值测定法和基于N2吸附等温线的BET方程、D-R方程,孔结构参数都不能正确反映活性炭对CO2的吸附特性;由CO2吸附等温线得到的D A模型参数也不适合分析活性炭吸附CO2特性;CO2吸附等温线的密度泛函理论(DFT)分析结果表明,CO2在活性炭上的吸附发生在极微孔内,DFT分析的微孔孔容与吸附等温线反映的吸附性能完全一致。因此,根据CO2吸附等温线的DFT模型是准确反映活性炭吸附CO2特性的表征分析方法。 相似文献