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Microporous Carbon (microporou + carbon)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Hydrogen storage properties of B- and N-doped microporous carbon

AICHE JOURNAL, Issue 7 2009
Lifeng Wang
Abstract A B- and N-doped microporous carbon has been synthesized via a substitution reaction. The obtained carbon exhibited much higher surface area than the previously reported B- and N-doped carbon. The hydrogen storage measurements indicated that the B- and N-doped microporous carbon had a 53% higher storage capacity than the carbon materials with similar surface areas. Furthermore, hydrogen storage via spillover was studied on Ru-supported B- and N-doped microporous carbon and a storage capacity of 1.2 wt % at 298 K and 10 MPa was obtained, showing an enhancement factor of 2.2. Ab initio molecular orbital calculations were also performed for the binding energies between the spiltover hydrogen atom and various sites on the doped carbon. The theoretical calculations can explain the experimental results well, which also shed light on the most favorable and possible sites with which the spiltover hydrogen atoms bind. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Analysis of multicomponent adsorption kinetics on activated carbon

AICHE JOURNAL, Issue 4 2003
L. P. Ding
An integrated mathematical model for the kinetics of multicomponent adsorption on microporous carbon was developed. Transport in this bidisperse solid is represented by balance equations in the macropore and micropore phases, in which gas-phase diffusion dominates the mass transfer in the macropores, with the phenomenological diffusivities represented by the generalized Maxwell,Stefan (GMS) formulation. Viscous flow also contributes to the macropore fluxes and is included in the MS expressions. Diffusion of the adsorbed phase controls the mass transfer in the micropore phase, which is also described in a similar way by the MS method. The adsorption isotherms are represented by a new heterogeneous modified vacancy solution theory formulation of adsorption, which has proved to be a robust method for adsorption on activated carbons. The model is applied to the coadsorption and codesorption of C2H6 and C3H8 on Ajax and Norit carbon, as well as the displacement on Ajax carbon. The effect of the viscous flow in the macropore phase is not significant for the cases studied. The model accurately predicts the overshoot behavior and rollup of C2H6 during coadsorption. The prediction for the heavier compound C3H8 is always satisfactory, though at higher C3H8 mole fraction, the overshoot extent of C2H6 is overpredicted, possibly due to neglect of heat effects. [source]

Influence of the OMCs pore structures on the capacitive performances of supercapacitor

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009
Gu-Zhen Nong
Abstract In the present study, two mesoporous carbons OMC-KIT-6 and OMC-SBA-16 were nanocasted using mesoporous silica of KIT-6 and SBA-16 as templates and furfuryl alcohol as carbon precursor. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) characterizations confirmed that the resultant samples are mesoporous carbons, and the as-prepared OMC-KIT-6 has an Ia3d ordered structure, whereas OMC-SBA-16 belongs to Im3m space group. The surface area and the average pore size are (1658 m2 g,1 and 3.4 nm) for OMC-KIT-6 and (1638 m2 g,1 and 2.9 nm) for OMC-SBA-16, respectively. The results of cyclic voltammograms and galvanostatic charge-discharge tests show that these two mesoporous carbons have excellent capacitive performances. But the difference of capacitive behavior between OMC-KIT-6 and OMC-SBA-16 may be a result of the difference of pore geometries of these two carbons. In order to find out the function of mesopore in a supercapacitor, we compared the capacitive properties of mesoporous and microporous carbons; the experiment results indicated that these two kinds of carbon exhibit nearly ideal capacitive behavior at low scan rate. When the scan rate is enhanced up to 50 mV s,1 the performance of mesoporous carbon is more stable than microporous carbon. This outcome demonstrated that mesopore plays an important role in forming double layers in the electrode materials. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Accessibility of simple gases in disordered carbons: theory and simulation

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009
T. X. Nguyen
Abstract We present a review of our recent studies on the accessibility of simple gases (Ar, N2, CH4 and CO2) in disordered microporous carbons using transition state theory (TST) and molecular simulation techniques. A realistic carbon model rather than the slit-pore approximation is utilised, providing more accurate understanding of complex adsorption equilibrium and dynamics behaviour at the molecular level in porous carbons, especially kinetic restriction of adsorbate molecules through highly constricted pore mouths of coals and molecular sieve carbons (MSC). This kinetic restriction leads to a molecular sieving effect which plays a vital role in gas separation using the MSCs. In particular, the realistic carbon model of a saccharose char used in a recent study was obtained by hybrid reverse Monte Carlo simulation. The time of adsorption or desorption of the single gas molecule between two neighbouring pores through a highly constricted window of the realistic saccharose char model was determined using TST. Finally, the validation of TST calculated results of adsorption and desorption times against experimental measurements as well as molecular dynamics simulation is also presented in this article. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]