Average Mesopore Size Research Articles

The quantitative impact of the mesopore size on the mass transfer mechanism of the new 1.9 μm fully porous Titan-C18 particles. I: Analysis of small molecules

Previous data have shown that could deliver a minimum reduced plate height as small as 1.7. Additionally, the reduction of the mesopore size after C18 derivatization and the subsequent restriction for sample diffusivity across the Titan-C18 particles were found responsible for the unusually small value of the experimental optimum reduced velocity (5 versus 10 for conventional particles) and for the large values of the average reduced solid–liquid mass transfer resistance coefficients (0.032 versus 0.016) measured for a series of seven n-alkanophenones. The improvements in column efficiency made by increasing the average mesopore size of the Titan silica from 80 to 120Å are investigated from a quantitative viewpoint based on the accurate measurements of the reduced coefficients (longitudinal diffusion, trans-particle mass transfer resistance, and eddy diffusion) and of the intra-particle diffusivity, pore, and surface diffusion for the same series of n-alkanophenone compounds. The experimental results reveal an increase (from 0% to 30%) of the longitudinal diffusion coefficients for the same sample concentration distribution (from 0.25 to 4) between the particle volume and the external volume of the column, a 40% increase of the intra-particle diffusivity for the same sample distribution (from 1 to 7) between the particle skeleton volume and the bulk phase, and a 15–30% decrease of the solid–liquid mass transfer coefficient for the n-alkanophenone compounds. Pore and surface diffusion are increased by 60% and 20%, respectively. The eddy dispersion term and the maximum column efficiency (295000plates/m) remain virtually unchanged. The rate of increase of the total plate height with increasing the chromatographic speed is reduced by 20% and it is mostly controlled (75% and 70% for 80 and 120Å pore size) by the flow rate dependence of the eddy dispersion term.

Synthesis and Characterization of Ni-Doped Carbon Aerogels

The carbon aerogels doped with nickel were produced by sol-gel, supercritical ethanol drying, and high-temperature carbonization, using resorcinol-furfural as carbon source, nickel nitrate as nickel source, absolute ethanol as dispersion medium, 1,2-epoxypropane as gel initiator, polyacrylic acid as the chelating agent. The carbon aerogels were characterized by nitrogen adsorption and XRD. The effects of the molar ratio of 1,2-epoxypropane to nickel on porosity of the Ni-doped carbon aerogels were investigated. It is found that the Ni-doped carbon aerogels have abundant mesopores and the doped nickel is dispersed in samples in metallic state and oxide or pure metal depending on the preparation conditions. The mesopore volume and average mesopore size all increase with the ratio of 1,2-epoxypropane to nickel.

Desilication of SSZ-33 zeolite – Post-synthesis modification of textural and acidic properties

Desilication conditions (concentration of NaOH, duration of the treatment) of SSZ-33 zeolite (CON topology) were investigated in respect to the textural and acidic properties of the obtained materials. As-synthesized borosilicate SSZ-33 was transformed by isomorphous substitution to Al-form. The alkaline treatment of Al-SSZ-33 zeolite resulted in the formation of mesopores and enhanced accessibility of Brønsted acid sites. The increase in the mesopore volume and also changes in the concentration of acid sites depends mainly on the concentration (pH) of the treatment. Simultaneously, the increase in the pH of the alkaline solution led to the slight increase in Brønsted acid sites and substantial decrease in the micropore volume more than 50%, in comparison with the parent material while the volume of mesopores increased significantly. All desilicated SSZ-33 zeolites are characterized by a broad mesopore-size distribution in the range of 5–20nm with the maximum depending both on the harshness and duration of the treatment. The average size of mesopores increases with increasing pH of NaOH solution.

Pore characteristics of Wilcox Group Coal, U.S. Gulf Coast Region: Implications for the occurrence of coalbed gas

Pore characteristics of 27 subbituminous coal samples (16mesh splits) from the Paleocene–Eocene Wilcox Group of north Louisiana (Ouachita and Caldwell Parishes) and south Texas (Zavala County) were examined in relation to desorbed gas content. Coal gas of the Wilcox Group is primarily biogenic in origin; thermogenic gas also may be present in some areas. On an as-received basis, desorbed gas contents range from 0.59 to 1.28m3/t for Ouachita Parish samples, 0.37 to 5.19m3/t for the Caldwell Parish samples, and 0.02 to 0.06m3/t for the Zavala County samples. For Louisiana coal samples, micropore surface area and volume are correlated to the desorbed gas content of the Wilcox Group coal (correlations: r=0.50 and 0.47, respectively), suggesting that micropore surface area and volume are important in terms of gas-holding capacity. Adsorption by micropores appears to be the primary form of gas storage for the Louisiana coal samples. Micropore surface area and volumes also are strongly correlated with the carbon/ash yield ratio (r=0.97 and 0.94, respectively), indicating that gas sorption occurs primarily on organic matter. Mineral matter appears to reduce the sorption capacity of the coal. Micropore width decreases with depth (r=−0.63), probably as the result of increasing pressure and coal rank with depth. For the Louisiana coal samples, mesopore surface area is negatively correlated with the carbon/ash yield ratio (r=−0.70), suggesting that mesopores are preferentially associated with mineral matter. Average mesopore size is correlated with desorbed gas (r=0.80) for the relatively shallow Ouachita Parish samples (average depth=441m, 1446ft); these results suggest that the permeability of the Wilcox coal is greater in the shallow stratigraphic intervals compared to deeper intervals. Additionally, mesopore size decreases with depth (r=−0.80). For Ouachita Parish coal samples, negative correlations of gas with mesopore surface area (r=−0.74) and mesopore volume (r=−0.56) strongly suggest that gas is not adsorbed in mesopores, and that free gas may be present in larger mesopores, macropores, or fractures of the Wilcox coal. Results also suggest that moisture in Ouachita Parish samples is present in mesopores; moisture in mesopores may have blocked gas adsorption.The low-gas south Texas samples (average depth=313m, 1026ft) are markedly different from the Louisiana samples. Specifically, micropore surface area and micropore volume are negatively correlated with desorbed gas for the Texas samples (r=−0.21 and −0.36, respectively). Geologic or environmental conditions probably were not conducive to the generation or storage of microbial gas in the Zavala County coals. The geologic settings (i.e., salinity of formation water, groundwater recharge, permeability of coal) of each study area are important factors that need to be considered in relation to the potential for generation or storage of microbial gas. In south Texas, tectonic stress may have led to a reduction in permeability in the Wilcox Group coal, creating an unfavorable environment for the generation or preservation of microbial gas. The subbituminous rank of the Zavala coals is also too low for significant thermogenic gas generation to have occurred.

Facile one-pot approach to the synthesis of spherical mesoporous silica nanoflowers with hierarchical pore structure

Hierarchically structured spherical mesoporous nanoflowers (HSMNF) with well-defined morphology and uniform size were synthesized by a hydrothermal method, in which a mixture of cyclohexane and water was used as the solvent, with cetylpyridinium bromide (CPB) as the template, tetraethyl orthosilicate as the source of inorganic silica, and urea as the hydrolysis additive. The flower size ranged from 200 nm to 500 nm, and the thickness of a “petal” was about 10 nm. We investigated the effects of solvent composition (Vcyclohexane/Vwater), hydrothermal temperature, and molar ratio of Si to CPB on morphology and structure. The presence of cyclohexane was found to be crucial for the nanoflowers to form, and a solvent with high cyclohexane content was beneficial for the formation of smaller and more uniform nanoflowers, whereas low cyclohexane content resulted in the collapse of the nanoflower structure. The optimal ratio of cyclohexane to water was 1:1 by volume. The hydrothermal temperature and molar ratio of Si to CPB strongly affected nanoflower size and structure, as well as petal thickness. The optimal hydrothermal temperature was 120 °C, and the optimal molar ratio of Si to CPB was 4.37. The sample synthesized under optimal conditions exhibited well-defined morphology and uniform flower size. Its BET surface area reached 502 m2/g. The nanoflowers were under 200 nm in diameter, and their average mesopore size was ca. 4 nm, as measured by N2 adsorption–desorption. Using synthesized nanoflowers as the support, we prepared a supported PdAu bimetallic catalyst for the hydrogenation of phenol. This catalyst exhibited high activity (with a conversion rate of up to 90%) and high selectivity for cyclohexanone (up to 92%). This nanoflower's morphology, high surface area, and large pore size may make it a valuable and promising material for applications in the catalysis, adsorption and controlled release of drugs fields.

An efficient dye-sensitized solar cell using surfactant-modified mesoporous carbon film as a counter electrode

Mesoporous carbon (MC), prepared by the carbonization of phenol resin using ethylene glycol as a pore forming agent, was used as the catalyst of the counter electrode in dye-sensitized solar cells (DSCs) fabricated by a paste coating method at low temperature, where a non-ionic surfactant, Triton X100, was used as a modifier of the paste. Fractal dimensions (DF) were used to evaluate the morphological difference of the MC films on the substrate with surfactant content. The efficiency of the DSCs using the MC modified by the surfactant reaches a maximum of 5.65% for 0.6 g MC with 0.1 mL surfactant. This is 46.5% higher than that of DSCs using activated carbon as a catalyst in the counter electrode, and 95.4% of the value obtained using DSCs with a Pt counter electrode under the same conditions. The performance improvement of the surfactant-modified MC counter electrode is attributed to a uniform MC film with a low DF value induced by adding the surfactant, a large average mesopore size of 34.6 nm that is favorable for mass transport, and a high-surface-area glassy carbon structure that has a high content of active sites. [New Carbon Materials 2013, 28(4): 254–261]

An efficient dye-sensitized solar cell using surfactant-modified mesoporous carbon film as a counter electrode

Mesoporous carbon (MC), prepared by the carbonization of phenol resin using ethylene glycol as a pore forming agent, was used as the catalyst of the counter electrode in dye-sensitized solar cells (DSCs) fabricated by a paste coating method at low temperature, where a non-ionic surfactant, Triton X100, was used as a modifier of the paste. Fractal dimensions (DF) were used to evaluate the morphological difference of the MC films on the substrate with surfactant content. The efficiency of the DSCs using the MC modified by the surfactant reaches a maximum of 5.65% for 0.6g MC with 0.1 mL surfactant. This is 46.5% higher than that of DSCs using activated carbon as a catalyst in the counter electrode, and 95.4% of the value obtained using DSCs with a Pt counter electrode under the same conditions. The performance improvement of the surfactant-modified MC counter electrode is attributed to a uniform MC film with a low DF value induced by adding the surfactant, a large average mesopore size of 34.6 nm that is favorable for mass transport, and a high-surface-area glassy carbon structure that has a high content of active sites.

Catalyst studies on the ring opening of tetrahydrofuran–dimethanol to 1,2,6-hexanetriol

The metal catalyzed hydrogenolysis of the biomass-derived THF–dimethanol to 1,2,6-hexanetriol using heterogeneous catalysts was investigated. Bimetallic Rh–Re catalysts (4wt% Rh and a Re/Rh (mol. ratio of 0.5) on a silica support gave the best performance and 1,2,6-hexanetriol was obtained in 84% selectivity at 31% conversion (120°C, 80bar, 4h); the selectivity reaches a maximum of 92% at 80°C. The product distribution at prolonged reaction times or higher temperatures or both shows the formation of diols and mono-alcohols, indicating that the 1,2,6-hexanetriol is prone to subsequent hydrodeoxygenation reactions. Different silica supports were investigated and optimal results were obtained with an amorphous silica featuring an intermediate surface area and an average mesopore size of about 6nm. TPR and XPS surface analysis support the presence of mixed Rh and Re particles. The redox Reδ+/ReTotal surface ratio correlates with the conversion in a volcano type dependency. Both gas phase as well as Rh200Re1OH cluster DFT calculations support an acid–metal bifunctional mechanism and explain the products distribution.

Ion exchange properties of cesium ion sieve based on zirconium molybdopyrophosphate

Cesium ion sieve (Cs-IS) based on a novel ion exchanger, zirconium molybdopyrophosphate, was prepared via an impregnation–recrystallisation–leaching procedure. The physicochemical properties were determined using X-ray photoelectron spectra (XPS), simultaneous thermal analysis (DSC-TGA), nitrogen adsorption–desorption and scanning electron microscopy (SEM). The synthesized material was found to have a cesium exchange capacity (CEC) up to 1.38mmol/g, a good thermal stability up to 1000°C and an average mesopore size of 13.54nm. The surface characterizations revealed that cesium was distributed over the rough surface of the irregular particles. The removal of cesium from acidic media in batch conditions was evaluated focusing on kinetic, isotherm and selectivity. Ion exchange equilibrium was attained within 15h and best fitted into pseudo-second-order model. The calculated empirical thermodynamic functions hinted the ion exchange of cesium onto Cs-IS could be simplified to an enthalpy-driven, physical adsorption process. The effects of initial pH and ionic strength were explored. The selectivity of Cs-IS for cesium ion was found to be fairly desirable considering the solution acidity and the presence of a substantial amount of sodium ions.

Development of mesopores in active carbons by iron catalyzed carbon hydrogenation

The effect of iron content in the pores of SUA active carbons on the changes in their porous structure in catalyzed hydrogenation of carbon was studied. It was found that preferential development of mesopores occurs during the reaction in adsorbents; increased content of the catalyst results in an increase in the fraction of wide mesopores and the average size of mesopores.

A novel route to highly monodispersed mesoporous silica spheres consisting of nano-sized particles

A novel route to highly monodispersed mesoporous silica spheres consisting of nano-sized silica particles will be presented. Simple hydrothermal treatment of monodispersed mesoporous silica spheres with ordered hexagonal structure resulted in internal structural transformation. Ordered hexagonal structure completely disappeared and instead nano-sized silica particles generated in the sphere. In consequence, the average mesopore size increased to 17nm from 2.3nm while retaining uniform spherical morphology. It was found that silver nanoparticles could be stabilized in mesopores of hydrothermally treated monodispersed silica spheres. In addition, by using the hydrothermally treated monodispersed mesoporous silica spheres as a template, monodispersed mesoporous carbon spheres with large mesopores could be obtained.

Trace element-incorporating octacalcium phosphate porous beads via polypeptide-assisted nanocrystal self-assembly for potential applications in osteogenesis

The promising future of calcium phosphates (CaP) as a group of biomedical materials with a wide range of functions, might ultimately depend on tuning their composition and microstructure. However, the disorderly growth and aggregation of CaP nanocrystals limit their practical application. This paper reports a strategy for designing polypeptide/trace elements (TE), dual mediating the self-assembly of octacalcium phosphate (OCP) nanocrystals, with multilayered porous cross section and TE dilute doping. Intriguing advantages such as bead morphology, mesoporous structure, tunable diameter (20–1000μm) and TE contents, biodegradability and bioactivity are obtained. The microcomputerized-tomography reconstruction reveals an interconnective macroporous architecture and a void volume of over 49.02% for the nearly close-packed bead scaffolds. The specific surface area and average mesopore size are 89.73m2g−1 and 2.75nm for the 180μm diameter bead group, and those of 500μm diameter beads are 130.17m2g−1 and 3.69nm, respectively. It is demonstrated that the bead production mechanism is a multistep process including liquid-like precursor formation, nanocrystal nucleation and aggregation, aggregate combination and bead growth. Such a multilayer structure of TE–OCP porous beads would have adequate physical strength to maintain their shape, in contrast to the physical weakness of pure OCP hollow shell. The beads exhibit good biocompatibility and degradability and encourage bone mineralization in the early stage in vivo. This study demonstrates the feasibility of developing highly porous calcium phosphate giant beads via biomimetic self-assembly for direct application in reconstructive surgery and other widespread applications such as tissue engineering and drug delivery.

Formation of Interpenetrating Hierarchical Titania Structures by Confined Synthesis in Inverse Opal

Hierarchical periodic titania nanostructures composed of a macroporous crystalline scaffold and mesoporous titania were prepared by confined synthesis. The strategy for the generation of these hierarchical structures involves preparation of inverse opal titania layers and subsequent filling of the interstitial macroporous voids with surfactant-containing titania precursors to obtain a mesostructured titania phase using the surfactant Pluronic P123. The formation of mesostructure in the confined space of the macroporous scaffold upon thermal treatment was investigated with in situ grazing incidence small-angle X-ray scattering (GISAXS). The macroporous scaffold strongly influences the mesostructure assembly and leads to much larger structural parameters of the formed mesostructure, this effect becoming more pronounced with decreasing pore size of the macroporous host. Furthermore, the inverse opal scaffold acts as a stabilizing matrix, limiting the shrinkage of the mesopores upon heating. This effect is coupled with an enhanced crystallization of the mesophase, which is attributed to the crystalline walls of the macroporous host. Sorption measurements of the final hierarchical titania structure of 5 μm thickness show that the porous system is fully accessible, has a high total surface area of 154 m(2)/g, and has an average mesopore size of 6.1 nm, which is about 20% larger than the pore size of 5.1 nm for the reference mesoporous film obtained on a flat substrate. These hierarchical structures were implemented as anodes in dye-sensitized solar cells (DSCs), showing a conversion efficiency of 4% under one sun illumination, whereas the calcined macroporous scaffold alone shows an efficiency of only 0.4%.

“One‐pot” preparation of basic amino acid–silica hybrid monolithic column for capillary electrochromatography

A novel "one-pot" strategy was developed for the preparation of amino acid (AA)-silica hybrid monolithic column. The basic AA (L-Arginine, L-Lysine and L-Histidine) was covalently incorporated into the silica hybrid skeleton via the epoxy ring-opening reaction between the amine group and the glycidyl moiety in γ-glycidoxypropyltrimethoxysilane (GPTMS), which was confirmed by elemental analysis and FT-IR studies, while the basic AA was also found to catalyze the polycondensation of tetramethoxysilane and GPTMS. The average mesopore and macropore sizes of the prepared basic AA-silica hybrid monolithic columns were 3.86 nm and 1.71 μm for the L-Lysine-silica hybrid monolith, 5.38 nm and 4.24 μm for the L-Arginine-silica hybrid monolith, and 6.38 nm and 1.24 μm for the L-Histidine-silica hybrid monolith. The hybrid monolith afforded a zwitterionic stationary phase for CEC, the direction and magnitude of EOF can be controlled by the pH of the mobile phase used. Besides an electrophoretic mechanism, the monoliths behave in a typical hydrophilic interaction with the analytes when ACN percentage in the mobile phase is over 40%. Four polar compounds (toluene, DMF, formamide and thiourea) were tested on the three AA-silica hybrid monolithic columns, and the best separation efficiency was observed in the L-Lysine-silica hybrid monolithic column, its theoretical plate height was down to 5.7 μm for thiourea when 20 mM HCOOH-HCOONH4 containing 20% ACN (pH 4.1) was used as a running buffer. The corresponding theoretical plate number for toluene, DMF, formamide and thiourea were 123,385, 103,620, 121,845 and 105,345 plates/m, respectively. Effective separation of phenols and peptides on the L-Lysine-silica hybrid monolithic column was achieved using CEC. We believe that this strategy paves a way for the easy preparation of various functional silica hybrid monolithic columns, aiming at different separation purposes.

Preparation of Adsorbent from Blue Coke Powder and its Application in Coking Wastewater

The low-cost blue coke industrial by-product, blue coke powder was used as raw material for the production of porous carbons adsorbent by steam activating at temperature of 800°C under the atmosphere of N2 for 60 minutes. The specific surface area and pore properties of the adsorbent were characterized by using N2 adsorption-desorption isotherms. Furthermore, the adsorption effects of the adsorbent for ammonia nitrogen in coking wastewater were investigated in terms of particle size, dosage of absorbent and adsorption time. The results show that the specific surface area is 620.94m2/g, the total pore volume is 0.4442cm3/g and the average mesopore size is 4.5808nm, the adsorbent possesses predominant mesoporous structures. In aeration, the removal rate of ammonia nitrogen can reach to 39.5% under the conditions of the ammonia nitrogen concentration of 625mg/L, the dosage of adsorbent 10g/L at the adsorption time of 60 minutes.

Importance of sample intraparticle diffusivity in investigations of the mass transfer mechanism in liquid chromatography

AbstractThe effective diffusivity of a nonretained (thiourea) and of a strongly retained (phenol) compounds were measured with the peak parking method in two different columns (both 150 × 4.6 mm) packed with two types of porous particles having different mesopore sizes [5 μm Jupiter‐C18, 320 Å and Luna(2)‐C18, 100 Å]. The eluent was a methanol–water mixture (10/90 v/v) and the temperature 294 K. The effective diffusivity data acquired were used to determine the intraparticle diffusivity, Dp, based on two different diffusion models. The first one assumes that the diffusion fluxes across the particles and in the interparticle volume are additive (parallel diffusion model). The second model was rigorously derived on the basis of the effective medium theory of diffusion (diffusion model) in a binary composite medium (particles + interparticle volume). In both models, it was assumed that the rate of equilibrium between the liquid and the solid phases was infinitely faster than the rate of axial diffusion along the column at zero flow rate. Both models provide physically meaningful intraparticle diffusivity coefficients that take into account the average mesopore size of the particles, their specific surface area, and the retention factor of the analyte. Although the actual effective intraparticle diffusivity remains unknown, these result confirm that the mass transfer resistance due to diffusion through the porous particles has almost negligible effects in reversed phase liquid chromatography due to the importance of surface diffusion. Combining the results of the peak parking method with the h data measured at high linear velocities allows the unambiguous measurement of the film mass transfer and the surface diffusion coefficients. © 2010 American Institute of Chemical Engineers AIChE J, 2011

Synthesis of mesoporous Nb2O5 with crystalline walls and investigation of their photocatalytic activity

We synthesize various kinds of mesoporous Nb2O5 samples by changing surfactants (P123 and Brij 56), followed by calcination (from 400 to 500 and 600 degrees C). The effect of these parameters helps to produce a well-defined mesoporous framework with crystallinity. The mesoporous Nb2O5 samples are well characterized by using small-angle X-ray scattering (SAXS) measurements, N2 adsorption-desorption isotherms, and wide-angle XRD measurements. In a P123 system, the frameworks are well crystallized to the TT-phase (pseudo-hexagonal) by calcination at 500 degrees C with retention of the mesoporous structures. In the Brij 56 system, after calcination at 500 degrees C, the framework is well retained in an amorphous state. It is proved that the thick walls prepared with P123 are easily crystallized in comparison to thin walls prepared with Brij 56. Furthermore, we investigate the photocatalytic activity by using several types of mesoporous Nb2O5 prepared with P123. All these mesoporous Nb2O5 samples show photocatalytic activity with their decomposition reaction of methylene blue (MB) molecules. It is concluded that the reaction rates depend on their crystallinities in the frameworks, surface areas, and average mesopore sizes.

Direct preparation of mesoporous carbon by pyrolysis of poly(acrylonitrile-b-methylmethacrylate) diblock copolymer

Direct pyrolysis of self-assembled polyacrylonitrile-block-polymethylmethacrylate (PAN-b-PMMA) diblock copolymer can be a promising route for fabricating an ordered carbon nanostructure. PAN-b-PMMA diblock copolymer was synthesized successfully by atom transfer radical (ATRP) polymerization in DMF at 90 °C with well-controlled molecular weight and narrow polydispersity. The resulting block copolymer self-assembled in the mixture of ethanol and water to form nanoparticles with a narrow size distribution. Furthermore, the high quality of the as-synthesized PAN-b-PMMA block copolymer experienced phase-separation to form a self-assembled nanostructure at 250 °C that was converted to a mesoporous carbon phase after heating at 800 °C. The pyrolyzed carbon product exhibited well-defined nanostructure with a high BET surface area of 860 m2 g−1 and an average mesopore size of 8.1 nm.

The mass transfer kinetics in columns packed with Halo-ES shell particles

AbstractThe average mesopore size of the new Halo-ES-Peptide shell particles is 160Å, markedly larger than that of the classical Halo shell particles (90Å). We found that this change causes a considerable decrease of the film mass transfer resistance measured for columns packed with these particles. We analyze data obtained by systematic measurements of the C term of the van Deemter equation for the peptide β-lipotropin (MW = 769Da), the protein insulin (MW = 5800Da), and a series of non-retained polystyrene standards (MW = 6400 and 13,200). The improvement in column performance is explained by an increase of the fraction of the external surface area of the shell that allows the entrance of the sample molecules inside the particle. The fraction of the shell surface accessible to a probe controls the rate of its external film mass transfer, i.e. its rate of transfer between the interstitial and the stagnant eluent. Although measurable, the increase in sample diffusivity through the porous shells does not account for the better performance of Halo-ES-peptide columns. Furthermore, the analysis of the HETPs data of small molecules (uracil, acetophenone, toluene, and naphthalene, MW< 150) reveals that the eddy diffusion (A) term of these new columns is 25% lower than that of the classical Halo columns. This result is consistent with the impact of intra-particle diffusivity on the eddy diffusion mechanism in packed columns. As shell diffusivity increases, so does the rate of transfer of sample molecules between the eluent stream-paths flowing through the packed particles and across the column diameter. Dispersion through short-range inter-channel and trans-column eddies is reduced.

Template synthesis of carbon nanofibers containing linear mesocage arrays.

Carbon nanofibers containing linear mesocage arrays were prepared via evaporation induced self-assembly method within AAO template with an average channel diameter of about 25 nm. The TEM results show that the mesocages have an elongated shape in the transversal direction. The results of N2 adsorption–desorption analysis indicate that the sample possesses a cage-like mesoporous structure and the average mesopore size of the sample is about 18 nm.