Nanoporous Materials

Poly[N,N¢-(1,4-phenylene)-3,3¢4,4¢-benzophenonetetracarboxylic amic acid] (PAmA) with grafted
poly(methyl methacrylate) (PMMA) side chains (PAmA-g-PMMA) was synthesized via thermally
induced graft copolymerization of methyl methacrylate (MMA) with ozone-pretreated PAmA in
the reversible addition-fragmentation chain-transfer (RAFT)-mediated process. The graft
copolymers were characterized by nuclear magnetic resonance (NMR), elemental analysis, X-ray
photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning
calorimetry (DSC), and molecular weight measurements. The “living” character of the grafted
PMMA side chains was ascertained in the subsequent extension of the PMMA side chains. The
nanoporous low dielectric constant (low-) polyimide (PI) films were obtained by thermal
imidization of the PAmA-g-PMMA films in argon, followed by thermal decomposition of the
PMMA side chains in air. The nanoporous PI films obtained from the RAFT-mediated PAmAg-
PMMA had well-preserved PI backbones, porosity in the range of 5-20%, and pore size in the
range of 5-15 nm. The pores were smaller, and the pore size distribution was more uniform
than those of the corresponding nanoporous PI films obtained via graft copolymers from the
conventional free radical process. Dielectric constants approaching 2.1 were obtained for the
nanoporous PI film with a porosity of about 20%.

Spatial confinement in nanoporous media affects the structure, thermodynamics and mobility of molecular soft matter often markedly. This article reviews thermodynamic equilibrium phenomena, such as physisorption, capillary condensation, crystallisation, self-diffusion, and structural phase transitions as well as selected aspects of the emerging field of spatially confined, non-equilibrium physics, i.e. the rheology of liquids, capillarity-driven flow phenomena, and imbibition front broadening in nanoporous materials. The observations in the nanoscale systems are related to the corresponding bulk phenomenologies. The complexity of the confined molecular species is varied from simple building blocks, like noble gas atoms, normal alkanes and alcohols to liquid crystals, polymers, ionic liquids, proteins and water. Mostly, experiments with mesoporous solids of alumina, gold, carbon, silica, and silicon with pore diameters ranging from a few up to 50 nm are presented. The observed peculiarities of nanopore-confined condensed matter are also discussed with regard to applications.
A particular emphasis is put on texture formation upon crystallisation in nanoporous media, a topic both of high fundamental interest and of increasing nanotechnological importance, e.g. for the synthesis of organic/inorganic hybrid materials by melt infiltration, the usage of nanoporous solids in crystal nucleation or in template-assisted electrochemical deposition of nano structures.

Spatial confinement in nanoporous media affects the structure, thermodynamics and mobility of molecular soft matter often markedly. This article reviews thermodynamic equilibrium phenomena, such as physisorption, capillary condensation, crystallisation, self-diffusion, and structural phase transitions as well as selected aspects of the emerging field of spatially confined, non-equilibrium physics, i.e. the rheology of liquids, capillarity-driven flow phenomena, and imbibition front broadening in nanoporous materials. The observations in the nanoscale systems are related to the corresponding bulk phenomenologies. The complexity of the confined molecular species is varied from simple building blocks, like noble gas atoms, normal alkanes and alcohols to liquid crystals, polymers, ionic liquids, proteins and water. Mostly, experiments with mesoporous solids of alumina, gold, carbon, silica, and silicon with pore diameters ranging from a few up to 50 nm are presented. The observed peculi...

Au cours des dernières décennies, un intérêt croissant est porté à la terre crue en tant qu'éco-matériau de construction pour son caractère local et la faible consommation d’énergie qui caractérise son cycle de vie global. Toutefois, sa résistance mécanique relativement faible et sa sensibilité à l'eau freinent le développement de ce matériau. Le principal but de cette étude est d’améliorer les propriétés mécaniques de briques de terre crue par l’emploi d’une nouvelle procédure de compactage à pression élevée maintenue pendant une durée correspondante au temps de consolidation. Un système de compactage a été élaboré afin de compacter le sol à haute pression en permettant le drainage de l’eau interstitielle. Dans un premier temps, les caractéristiques géotechniques du matériau d'étude ont été déterminées. Après compactage à 25, 50 et 100 MPa, les échantillons ont été placés dans une enceinte climatique (25°C, humidité relative de 62 %) jusqu’à équilibre hydrique, puis testés afin d’évaluer leur module d’Young et leur résistance mécanique en compression. Cette nouvelle méthode de compactage à haute pression a permis d'atteindre des performances mécaniques élevées. Ainsi, un des principaux freins à l'utilisation de la terre crue comme matériau de construction serait levé.

Extensive consumption of carbon resources has led to decreasing reserves of fossil fuels and growing concern about global warming. This dilemma has promoted a shift in the economy to develop new long-term, environmentally friendly, and sustainable sources for fuels and chemicals to replace fossil fuel-based sources. Renewable biomass is an ideal
alternative, as it is abundant, and relatively cheap. Among current biofuel resources, 5-hydroxymethylfurfural (5-HMF) is a versatile intermediate between biomass-based carbohydrate chemistry and fossil fuel-based industrial organic chemistry, which can be used to synthesize a broad range of chemicals that are currently derived from fossil fuel based resources. Carbohydrates became the preferred feedstock for high yield production
of 5-HMF, and the most convenient route for the synthesis of 5-HMF is the acid-catalyzed dehydration of hexose. Within this context, a variety of processes were developed for the synthesis of 5-HMF from dehydration of fructose involving various solvents, including water, organic solvents, and biphasic systems. Likewise, a range of catalysts were employed, such as homogeneous acid catalysts and metal chlorides, which showed high
catalytic activity. Heterogeneous catalysts have also been receiving attention due to their advantages such as easy recovery and recyclability. In the current research, microwave assisted synthesis of 5-HMF by dehydration of fructose over various acidic porous catalysts, such as periodic mesoporous organosilica (PMO), carbon materials, and metal
organic frameworks (MOFs), was investigated. The results showed that the obtained 5-HMF yields were satisfactory, and more importantly highlighted some of the properties of porous heterogeneous catalysts that may improve the production of 5-HMF.

Limited robustness is a serious drawback for superhydrophobic coatings and degrades the performance of superhydrophobic surfaces in practical applications. Although fluororeagents have excellent durability for superhydrophobicity, their use has been restricted due to various health and environmental concerns. In this work, we describe a facile and efficient fabrication strategy for creating robust fluorine-free superhydrophobic composite coatings that are prepared by a simple dip-dry method, in which the H 3 BO 3-incorporated SiO 2 −alkyl-silane coatings are deposited on woven cotton fabric surfaces followed by polydimethylsiloxane modification. The coated surface shows a large water contact angle of 157.95 ± 2°and a small sliding hysteresis angle (SHA) of 3.8 ± 0.6°, demonstrating excellent superhydrophobicity. The coated fabric surface also exhibited robustness and durability, withstanding a tape-peeling test (under 48.05 kPa) for around 80 repetitions and sandpaper rubbing (loaded 100 g) for 40 cycles. Furthermore, the coated fabric surface displayed self-healing and oil−water separation capacities. The developed superhydrophobic coatings in this study are robust, environmentally benign, and easy to fabricate, showing promising applications in textile industries.

The field of plasmonics is capable of enabling interesting applications in different wavelength ranges, spanning from the ultraviolet up to the infrared. The choice of plasmonic material and how the material is nanostructured has significant implications for ultimate performance of any plasmonic device. Artificially designed nanoporous metals (NPMs) have interesting material properties including large specific surface area, distinctive optical properties, high electrical conductivity, and reduced stiffness, implying their potentials for many applications. This paper reviews the wide range of available nanoporous metals (such as Au, Ag, Cu, Al, Mg, and Pt), mainly focusing on their properties as plasmonic materials. While extensive reports on the use and characterization of NPMs exist, a detailed discussion on their connection with surface plasmons and enhanced spectroscopies as well as photocatalysis is missing. Here, we report on different metals investigated, from the most used nanoporous gold to mixed metal compounds, and discuss each of these plasmonic materials' suitability for a range of structural design and applications. Finally, we discuss the potentials and limitations of the traditional and alternative plasmonic materials for applications in enhanced spectroscopy and photocatalysis.

The use of raw earth as construction material can save embodied and operational energy because of low processing costs and passive regulation of indoor ambient conditions. Raw earth must however be mechanically and/or chemically stabilised to enhance stiffness, strength and water durability. In this work, stiffness and strength are enhanced by compacting raw earth to very high pressures up to 100 MPa while water durability is improved by using alkaline solutions and silicon based admixtures. The effect of these stabilisation methods on hygro-mechanical behaviour is explored and interpreted in terms of the microstructural features of the material. Stiffness and strength are defined at different humidity levels by unconfined compression tests while the moisture buffering capacity is measured by humidification/desiccation cycles as prescribed by the norm ISO 24353 (2008). As for the microstructural characterisation, different tests (i.e. X-Ray diffractometry, Infrared Spectroscopy, Mercury Intrusion Porosimetry, Nitrogen Adsorption) are performed to analyse the effect of stabilisation on material fabric and mineralogy. Results indicate that the use of alkaline activators and silicon based admixtures significantly improves water durability while preserving good mechanical and moisture buffering properties. Similarly, the compaction to very high pressures results in high levels of stiffness and strength, which are comparable to those of standard masonry bricks. This macroscopic behaviour is then linked to the microscopic observations to clarify the mechanisms through which stabilisation affects the properties of raw earth at different scales.

MIL-53-Cu has been synthesized hydrothermally and has been used for the first time for gas separation. MIL-53-Cu shows adsorption capacities of 8.1, 0.7 and 0.5 m.mol/g, respectively, for CH4, CO2 and H2 at 30 bar and 298 K. The high CH4 adsorption capacity of MIL-53-Cu maybe attributed to the high pore volume and large number of open metal sites. The high selectivity for CH4 over CO2 (11.5) and H2 (16.2), suggests that MIL-53-Cu is a effective adsorbent material for the separation of CH4 from gas mixtures.

A B S T R A C T The integration of supercapacitors with enzymatic biofuel cells (BFCs) can be used to prepare hybrid devices in order to harvest significantly higher power output. In this study, a supercapacitor/biofuel cell hybrid device was prepared by the immobilisation of redox enzymes with electrodeposited poly(3,4-ethylenedioxythiophene) (PEDOT) and the redox polymer [Os(2,2′-bipyridine) 2 (polyvinylimidazole) 10 Cl] +/2+ (Os(bpy) 2 PVI) on dealloyed nanoporous gold. The thickness of the deposition layer can be easily controlled by tuning the deposition conditions. Once charged by the internal BFC, the device can be discharged as a supercapacitor at a current density of 2 mA cm −2 providing a maximum power density of 608.8 μW cm −2 , an increase of a factor of 468 when compared to the power output from the BFC itself. The hybrid device exhibited good operational stability for 50 charge/discharge cycles and ca. 7 h at a discharge current density of 0.2 mA cm −2. The device could be used as a pulse generator, mimicking a cardiac pacemaker delivering pulses of 10 μA for 0.5 ms at a frequency of 0.2 Hz.

A two-step electrochemical anodisation approach was adopted in this work to create a series of highly ordered mesopores etched with different diameter (60 to 160 nm) and uniform nanotube length in anodised aluminium oxide (AAO). The loading and release characteristics of model drug (indomethacin) and drug carriers (micelles named Pluronic F127, TPGS, PEO-PPO-PEO) were presented to investigate the influence of micelle size, pore diameter and surface modification of AAO on release studies. Surface chemistry was varied via silanation process, using AFTES and PFPTES. It was discovered that quicker release of drugs was induced by larger pore size and smaller micelles. Moreover drug release was found to favour hydrophobic surface as the release was faster in PFPTES modified AAO than the one with APTES.

The understanding of fluid flow inside a fixed-bed adsorption column is crucial as mass transfer in the bed is influenced by the column hydrodynamics. In this study, a numerical model has been developed to simulate the adsorption of chemical species of CO2/CH4 mixture inside the geometry containing solid adsorbent particles, namely nanoporous activated carbon. The laboratory-scale geometry consists of a High-
Pressure Volumetric Analyzer (HPVA) adsorption chamber; where in this study the effect of heat transfer within the bed is assumed negligible. The Computational Fluid Dynamics (CFD) simulations are performed using ANSYS Fluent® 14.0 to investigate the effect of flow rate on CO2 adsorption capacity through the variation of the inlet feed velocities. Simulation results show that the amount of gas adsorbed inside the column varies inversely with the increase of inlet velocity, which is in agreement with the experimental data. In addition, pressure gradient across the domain shows an increment trend as the flow rate of the gases increases.

Pt-USY-712 (Si/Al = 6) and three SBA-15 catalysts (metal-loaded with 1 wt% Pt, 1 wt% Ni or 0.5 wt% Pt and 0.5 wt% Ni) were prepared and characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD), N$$_{2}$$2 adsorption porosimetry / BET and transmission electron microscopy (TEM). The catalysts were then tested in the hydroisomerisation and hydrocracking of $$n$$n-heptane using a micro-reactor at atmospheric pressure, and the products were analysed by GC-FID. Reaction temperatures ranged from 250–$$400\,\,^{\circ }\hbox {C}$$400∘C while the W/F values of $$n\hbox {-C}_{7}$$n-C7 varied from 224.70–550.57 kg $$\hbox {mol}^{-1}$$mol-1. The coke content of each catalyst was measured using thermo gravimetric analysis (TGA). The catalytic activity was highest on Pt-USY-712 at the lowest reaction temperatures due to (a) the presence of strong Brønsted acids sites on the zeolite and (b) the smaller and more highly dispersed metal clusters on Pt-USY-712, relative to Pt-SBA-15. The activity was higher on the bimetallic Pt/Ni-SBA-15 than on mono-metallic Pt-SBA-15 as the co-impregnation of Ni with Pt enhanced the distribution of the metal clusters on the catalyst and resulted in improved surface area for reaction. The Pt-SBA-15 and Pt/Ni-SBA-15 catalysts both had the lowest and approximately equal coke percentages with 0.116 and 0.119 wt%, respectively.

Abstract Development of efficient hydrogen evolution reaction (HER) catalyst composed of earth-abundant elements is scientifically and technologically important for water splitting associated with the conversion and storage of renewable energy. Herein, we report a new class of nickel-phosphide/graphitic carbon (Ni2P@GC) hybrid prepared by a two-step strategy: first pyrolyzing of Ni-based metal–organic frameworks (Ni-MOFs) and then phosphating. The HER performance of the as-prepared material was tested using linear sweep voltammetry (LSV) method in 0.5 M H2SO4 electrolyte solution. Unexpectedly, the Ni2P@GC exhibited superior HER performance with the onset potential started at −93 mV and good durability due to the synergistic interaction of active Ni2P nanoparticles and graphitic carbon support. This study offers an attractive electrocatalyst toward the power-efficient electrochemical preparation of hydrogen energy.

Mesoporous silica material Santa Barbara Amorphous-15 (SBA-15) and functionalized SBA-15 with amino functional group were synthesized in order to investigate its potential use as an adsorbent for adsorption of binary and multi heavy metals ions from aqueous solution. The characteristics of SBA-15 before and after functionalization were achieved, such as Brunauer-Emmett-Teller (BET) surface area and thermal gravimetric analysis (TGA). The adsorption of binary system consisting of Ni(II) and Co(II) on NH 2-SBA-15 was investigated, it was found that the percentage removal for Ni(II) ions in binary system was less than in single system by 64.67% which confirms the presence of competition between these ions, and the effect was much clearly in higher concentrations. The competitive adsorption for six metals ions on NH 2-SBA-15 was studied, and it was obtained that the adsorbent had an attraction toward metal ions in reducing order as follows: Pb 2+ ˃ Cr 3+ ˃ Cu 2+ ˃ Cd 2+ ˃ Ni 2+ ˃ Co 2+ which show that Pb was the most adsorbed metal at NH 2-SBA-15. It was also found that the Ni 2+ adsorption efficiency acquired from the single-metal aqueous solution (99%) better than in multi-metals aqueous solution (42%), indicating the presence of competition between the metallic elements for adsorption by NH 2 groups.

Abstract Pt-USY-712 (Si/Al = 6) and three SBA-15 catalysts (metal-loaded with 1 wt% Pt,
1 wt% Ni or 0.5 wt% Pt and 0.5 wt% Ni) were prepared and characterised using scanning
electron microscopy (SEM), X-ray diffraction (XRD), N2 adsorption porosimetry / BET and
transmission electron microscopy (TEM). The catalysts were then tested in the hydroiso-
merisation and hydrocracking of n-heptane using a micro-reactor at atmospheric pressure,
and the products were analysed by GC-FID. Reaction temperatures ranged from 250–400 ◦C
while the W/F values of n-C7 varied from 224.70–550.57 kg mol−1. The coke content of
each catalyst was measured using thermo gravimetric analysis (TGA). The catalytic activity
was highest on Pt-USY-712 at the lowest reaction temperatures due to (a) the presence of
strong Brønsted acids sites on the zeolite and (b) the smaller and more highly dispersed
metal clusters on Pt-USY-712, relative to Pt-SBA-15. The activity was higher on the bimetal-
lic Pt/Ni-SBA-15 than on mono-metallic Pt-SBA-15 as the co-impregnation of Ni with Pt
enhanced the distribution of the metal clusters on the catalyst and resulted in improved sur-
face area for reaction. The Pt-SBA-15 and Pt/Ni-SBA-15 catalysts both had the lowest and
approximately equal coke percentages with 0.116 and 0.119 wt%, respectively.

The spontaneous evolution of nanoporous sponges during dealloying is a fascinating process in nanotechnology. Originally
mostly studied as a (homogeneous) corrosion process, [ 1 ] dealloying has been early-on employed to produce Raney nickel. [ 2 ] Nanoporous gold (npAu) and other metals have been meanwhile proposed for applications from high-strength material, [ 3 ] catalysis, [ 4 ] and actuators [ 5 ] to energy storage [ 6 ] or biosensors. [ 7 ] Naturally, it is very important to understand the mechanical behavior and integrity of npAu and related nanometer-scaled functional materials. [ 8 ] Dealloying is often involved in localized corrosion and stress corrosion cracking, which is a major concern for the stability of metallic materials in general. [ 9 ] A localized dealloying mode can be triggered, for example, by a local breakdown of protective molecular-thin organic inhibitor fi lms. Due to the volume decrease in npAu, [ 10 ] the localized dealloying leads to stress that results in initiation and propagation of cracks. [ 11 ] Local changes in structure and morphology of the surface can thus decisively infl uence the fate of materials. However, a satisfying understanding of initial crack nucleation is still lacking. [ 12 ] Clarifi cation of the mechanisms of the incipient crack initiation and ensuing propagation implies unraveling the interplay and infl uence of both the substrate and the organic fi lm properties. Corrosion inhibition as well as functionalization
are often achieved by self-assembled monolayers (SAMs) employing molecules such as phosphonic acids, silanes, thiols, or selenols. [ 13 ] Apart from possibly preventing catastrophic cracking, a better understanding of the initial surface processes will also improve structural control during formation of (functional) nanoporosity. [ 14 ] Here, we offer a new approach to monitor crack initiation and propagation correlated to defined surface states. We control the localized dealloying on well-defi ned inhibitor fi lm–covered Cu 3 Au binary alloy surfaces by an applied electrochemical potential. The atomically smooth starting surfaces were prepared by sputter-annealing cycles in ultrahigh vacuum (UHV). We employed (1) defi ned surface orientations, which offer a variation of interatomic distances along the substrate surfaces, as well as (2) inhibition by different (molecularly ordered) SAMs based on cross-linking and noncross-linking thiol and selenol precursors. The observed density of initial defects and resulting cracks critically depends on the surface orientation. To our surprise we also fi nd a crystallographic nature of the cleavage planes within the opening microcracks. The detailed crack morphology also indicates a dependence on the chosen SAM precursor. We connect thus the understanding of well-ordered molecular interfaces on the atomic scale with a dangerous but fascinating macroscopic corrosion phenomenon.

The field of plasmonics is capable of enabling interesting applications in different wavelength ranges, spanning from the ultraviolet up to the infrared. The choice of plasmonic material and how the material is nanostructured has significant implications for ultimate performance of any plasmonic device. Artificially designed nanoporous metals (NPMs) have interesting material properties including large specific surface area, distinctive optical properties, high electrical conductivity, and reduced stiffness, implying their potentials for many applications. This paper reviews the wide range of available nanoporous metals (such as Au, Ag, Cu, Al, Mg, and Pt), mainly focusing on their properties as plasmonic materials. While extensive reports on the use and characterization of NPMs exist, a detailed discussion on their connection with surface plasmons and enhanced spectroscopies as well as photocatalysis is missing. Here, we report on different metals investigated, from the most used na...

Santa Barbara Amorphous (SBA)-15 supported 1% (Pt–Ni), 1% (Pt–Co) and 1% (Ni–Co) bimetallic catalysts in a heterogeneous reaction for enhancement hydroisomerization and hydrocracking production during reforming or decomposition of n-heptane. The structural and textural features of the nanoporous silicas, both with and without encapsulated nanoparticles, were characterized using small-angle X-ray diffraction, scanning electron microscopy, EDAX, nitrogen adsorption– desorption porosimetry (Brunauer–Emmett–Teller) surface area analysis, Fourier-transform infrared spectroscopy and transmission electron microscopy. The catalytic performance was evaluated at 250–400°C under atmospheric pressure in a plug-flow reactor in a catalyst testing rig under tightly controlled conditions of temperature, reac-tant flow rate and pressure. The species leaving the reactor were analysed by Gas Chromatography. The results show that 1% (Pt–Ni)/SBA-15, 1% (Pt–Co)/SBA-15 and 1% (Ni– Co)/SBA-15 had a high activity for conversion of n-heptane (around 85%). The selectivity of isomerization is not high, so further studies have to be carried out in the future.

We study water adsorption-induced deformation of a monolithic, mesoporous silicon membrane traversed by independent channels of 8 nm diameter. We focus on the elastic constant associated with the Laplace pressure-induced deformation of the membrane upon capillary condensation, i.e. the pore-load modulus. We perform finite-element method (FEM) simulations of the adsorption-induced deformation of hexagonal and square lattices of cylindrical pores representing the membrane. We find that the pore-load modulus weakly depends on the geometrical arrangement of pores, and can be expressed as a function of porosity. We propose an analytical model which relates the pore-load modulus to the porosity and to the elastic properties of bulk silicon (Young's modulus and Poisson's ratio), and provides an excellent agreement with FEM results. We find good agreement between our experimental data and the predictions of the analytical model, with the Young's modulus of the pore walls slightly lower than the bulk value. This model is applicable to a large class of materials with morphologies analogous to mesoporous silicon. Moreover, our findings suggest that liquid condensation experiments allow one to elegantly access the elastic constants of a mesoporous medium.

The use of raw earth as construction material can save embodied and operational energy because of low processing costs and passive regulation of indoor ambient conditions. Raw earth must however be mechanically and/or chemically stabilised to enhance stiffness, strength and water durability. In this work, stiffness and strength are enhanced by compacting raw earth to very high pressures up to 100 MPa while water durability is improved by using alkaline solutions and silicon based admixtures. The effect of these stabilisation methods on hygro-mechanical behaviour is explored and interpreted in terms of the microstructural features of the material. Stiffness and strength are defined at different humidity levels by unconfined compression tests while the moisture buffering capacity is measured by humidification/desiccation cycles as prescribed by the norm ISO 24353 (2008). As for the microstructural characterisation, different tests (i.e. X-Ray diffractometry, Infrared Spectroscopy, Mer...

The particulate nanoporous material MCM-48 (Mobil Crystalline Material No. 48) was synthesized and characterized in order to use it as an adsorbent for the removal of adsorbate, such as aniline and nitro-substituted anilines, including 2-nitroaniline, 3-nitroaniline, and 4-nitroaniline from wastewater. The characterizations of MCM-48 were investigated by applying XRD, SEM, EDAX, BET surface area, and FTIR. The adsorption kinetics was investigated too. The batch adsorption studies demonstrated that the MCM-48 had a significant ability to the adsorption of aniline and nitro-substituted aniline from wastewater. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The four molecules adsorbed according to type I Langmuir adsorption with a maximum uptake were calculated to be approximately 94 mg g À1. The findings showed that the kinetics of the reaction is very rapid and followed a pseudo-second-order model. It is clearly indicated that the Langmuir model is more suitable for chemical organic compounds adsorption on mesoporous material than the Freundlich model.

This paper describes a study of CO 2 diffusion and adsorption in layered double-hydroxide (LDH) adsorbents using a gravimetric method. Four different particle size fractions, namely, 53-75, 75-90, 90-180, and 180-300 µm, were used in the study. The LDH materials were calcined in situ prior to the experiments, which resulted in significantly higher CO 2 adsorption capacities than previously reported. The CO 2 adsorption was shown to follow a Sips-type isotherm, while the adsorption capacity at saturation was found to be independent of the particle size. Two models, the homogeneous surface diffusion model (HSDM) and the bidisperse pore model (BPM), were used to fit the experimental data and to estimate the diffusivities. The main assumption made in the BPM is that the adsorbent particle is an agglomerate of a number of equal-sized, single-crystal microparticles, and before a CO 2 molecule is adsorbed in the microparticles, it has to diffuse through the intercrystalline porous region. Both models perform well in fitting the experimental data. However, the HSDM yields diffusivities that are a strong function of the particle size, whereas the diffusivities estimated using the BPM are almost independent of the particle size.

N2 and CO condensed into nanoporous glasses have been investigated by vapor pressure measurements and x-ray diffraction as a function of temperature and fractional filling. The pore material is stable with respect to bulk condensation for any fractional filling. The adsorbate on the pore walls has to be distinguished from the capillary condensate in the center of the pores. This

N-2 and CO condensed into nanoporous glasses have been investigated by vapor pressure measurements and a-ray diffraction as a function of temperature and fractional filling. The pore material is stable with respect to bulk condensation for any fractional filling. The adsorbate on the pore walls has to be distinguished from the capillary condensate in the center of the pores. This distinction can be made not only in the Liquid, but also in the solid state. The solid capillary condensate is quasi-hcp at higher temperatures. N-2 remains in this state down to the lowest temperatures, even in pores as large as 130 Angstrom diameter, whereas CO transforms into the orientationally ordered Pa3 phase. On heating an orientationally disordered intermediate phase with a fec center-of-mass lattice is observed.