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Showing papers in "Journal of Porous Materials in 1996"


Journal ArticleDOI
TL;DR: Woodceramics as mentioned in this paper are new porous carbon materials obtained by carbonizing wood or woody material impregnated with thermosetting resin such as phenol resin in a vacuum furnace.
Abstract: Woodceramics are new porous carbon materials obtained by carbonizing wood or woody material impregnated with thermosetting resin such as phenol resin in a vacuum furnace. During the carbonizing process, thermosetting resin changes into glassy carbon, which has superior corrosion resistance and mechanical strength, reinforces the material and suppresses the fissures and warps (caused by the porous structure specific to wood) that develop during thermoforming. The dimension, weight decrease rate, and electrical characteristics depend on the thermoforming temperature. The manufacturing method of Woodceramics is introduced in this paper and various industrial uses, such as electromagnetic shields, are discussed.

69 citations


Journal ArticleDOI
TL;DR: A lamellar hydrocalumite-type [Ca2Al(OH)6]NO3·mH2O, (HC) was synthesized and characterized by X-ray diffraction analysis (XRD), surface area, pore size measurements, CO2-Thermal Programmed Desorption, and later tested as catalysts in the double bond isomerization of 1-butene as discussed by the authors.
Abstract: A lamellar hydrocalumite-type [Ca2Al(OH)6]NO3·mH2O, (HC), was synthesized and characterized by X-ray diffraction analysis (XRD), surface area, pore size measurements, CO2-Thermal Programmed Desorption, and later tested as catalysts in the double bond isomerization of 1-butene. The layered structure of HC collapses above 523 K yielding an amorphous material at 573 K which upon calcination at 873–973 K transforms into a mixture of CaO and mayenite Ca12Al14O33. The calcination temperature has a marked effect in the formation of basic sites. Thus for example, HC calcined at 1073 K shows 90% of strong basic sites (CO2 desorption at 1023 K) while they are absent in HC calcined at 573–673 K. HC calcined at 973 K shows high catalytic activity (74% conversion) in the isomerization of 1-butene without any appreciable deactivation after 4 h on stream.

66 citations


Journal ArticleDOI
TL;DR: A series of Ga-containing hydrotalcite-like materials (GaHTs), [Mg1-xGa x (OH)2](CO3)x/2 ·mH2O wherex = 0.072 ∼ 0.8], was synthesized by a coprecipitation method as discussed by the authors.
Abstract: A series of Ga-containing hydrotalcite-like materials (GaHTs), [Mg1-xGa x (OH)2](CO3)x/2 ·mH2O wherex = 0.072 ∼ 0.35 (Mg/Ga = 12.9 ∼ 1.8), was synthesized by a coprecipitation method. The resulting solids were characterized by means of X-ray diffraction, thermal gravimetric and infrared analyses. All GaHTs showed diffraction patterns typical of Mg-Al hydrotalcites. Small amounts of brucite, Mg(OH)2, were detected only in the GaHT with Mg/Ga = 12.9. Attempts to obtain Ga-richer hydrotalcites, Mg/Ga < 1.8, resulted in solids with an invariably constant Mg/Ga = 1.8 ratio, which appears to be the maximum Ga content limit. Judging from the TGA pattern of a GaHT (Mg/Ga = 7.7), the layered structure is stable up to ca. 573 K, and at 873 K the resulting solid shows a MgO-like diffraction pattern, suggesting that Ga3+ may be replacing some Mg2+ ions in MgO. Once their layered structure collapses (i.e., at 873 K), GaHT can be easily converted back into the original layered material by treating in a carbonate-containing aqueous solution, i.e., they show the “memory effect” typical of Mg-Al hydrotalcites.

43 citations


Journal ArticleDOI
TL;DR: Phenyltrimethoxysilane (PhTMS) was hydrolyzed or cohydrolyzed with tetramethoxisilane to make aerogels and xerogels by further pyrolyzing these gels in inert atmosphere up to 1500°C.
Abstract: Phenyltrimethoxysilane (PhTMS) was hydrolyzed or cohydrolyzed with tetramethoxysilane (TMOS) to make aerogels and xerogels Porous SiC/silicon oxycarbide glasses were prepared by further pyrolyzing these gels in inert atmosphere up to 1500°C The pore structure and chemical nature were studied by nitrogen and water sorption measurement, chemical analysis, X-ray diffraction and scanning electron microscopy It has been found that the addition of PhTMS into TMOS gels decreased the surface area and porosity of TMOS gels, but enhanced their hydrophobicity and thermal stability Pyrolyzing 25 mole% PhTMS-75 mole% TMOS aerogel in argon resulted in porous silicon oxycarbide glass which has a surface area of 581 m2/g at 1000°C Pyrolyzing pure PhTMS gels at 1400°–1500°C produced porous SiC/C/silicon oxycarbide composites having surface areas in the range of 400–500 m2/g

42 citations


Journal ArticleDOI
TL;DR: In this paper, the synthesis of highly ordered mesoporous materials derived from a layered polysilicate kanemite has been reviewed and the properties and potential applications of these materials are also briefly outlined.
Abstract: Synthesis of highly ordered mesoporous materials derived from a layered polysilicate kanemite has been reviewed. Silica-surfactant mesostructured materials are obtained by the reaction of kanemite with alkyltrimethy lammonium ions. Calcination of silica-surfactant mesophase materials yields ordered mesoporous molecular sieves. Substantial replacement of alkyltrimethylammonium ions for interlayer Na ions and careful adjustment of pH in the reaction media are necessary for the preparation of ordered mesoporous silica. Formation processes of the silicate-surfactant mesophase materials have been monitored by in-situ powder X-ray diffraction technique which has indicated the presence of a lamellar phase before the appearance of a hexagonal phase. Comparison of these materials with MCM-41 is briefly mentioned. The properties and potential applications of these materials are also briefly outlined.

40 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of the initial gel structure on the preparation of the xerogels is discussed and a method of obtaining ambient pressure-dried aerogels was described.
Abstract: Silica aerogel is a sol-gel prepared material characterized by high porosity and large inner surface area. Aerogels can be prepared with a high transparency and low thermal conductivity, giving a material excellent for application as transparent thermal insulator. The traditional route to prepare silica aerogels is by formation of an alcogel by hydrolysis and condensation of silicon alkoxides followed by supercritical drying in an autoclave at high pressure (–100 atm). Unfortunately, this process is expensive and might be dangerous, so drying methods have been developed that operate under ambient conditions. In previous work, we have shown that gels can be strengthened and stiffened by providing new monomers to the alcogel giving xerogels with similar properties as aerogels by drying at ambient pressure (porosity up to 90%). This method of obtaining ambient pressure dried aerogels will be described and special emphasis will be given on the effect of the initial gel structure on the preparation of the xerogels.

38 citations


Journal ArticleDOI
TL;DR: In this paper, mesoporous molecular sieves of silica, and alumina, and porous materials of titania, zirconia, and niobia were synthesized by cationic and/or neutral templating methods.
Abstract: Mesoporous molecular sieves of silica, and alumina, and porous materials of titania, zirconia, and niobia were synthesized by cationic and/or neutral templating methods. These porous materials were characterized by powder X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherms and water adsorption-desorption isotherms. Mesoporous molecular sieves of silica with surface areas of 956 and 1072 m2/g and of alumina with surface area of 407 m2/g were synthesized. The Ti1 Zr and Nb oxide porous materials, however, showed smaller surface areas of 258, 178, and 77 m2/g, respectively, after calcination at 300°C and exhibited only small peaks for mesopores as determined by the pore-size. distributions.

31 citations


Journal ArticleDOI
TL;DR: In this article, fly ash and polypropylene were used to produce smooth-surfaced test blocks. Compressive and tensile strength, abrasion, water absorption, thermal conductivity and specific heat capacity tests were done on these blocks.
Abstract: This work was undertaken on two different wastes to produce a new construction material which may have good insulation and mechanical strength properties. Fly ash, a waste produced at power stations, and polypropylene, a waste generated mostly from packaging, were used to produce smooth-surfaced test blocks. Compressive and tensile strength, abrasion, water absorption, thermal conductivity and specific heat capacity tests were done on these blocks. It was concluded that these two wastes could be utilized to produce useful insulation and other building materials and at the same time eliminate environmental problems that may be caused by them if disposed off.

28 citations


Journal ArticleDOI
TL;DR: In this paper, the synthesis of mesoporous aluminosilicates and aluminum oxides based on surfactant templating methods is discussed, where the incorporation of aluminum in the silicate frameworks generates acid sites and ion exchange sites.
Abstract: This article reviews syntheses of mesoporous aluminosilicates and aluminum oxides based on surfactant templating methods. The incorporation of aluminum in the silicate frameworks generates acid sites and ion-exchange sites. Both, tetrahedral framework aluminum and octahedral extraframework aluminum can be present, depending on the aluminum precursor used. The aluminum-containing structures tend to be less ordered than their purely siliccous analogs. Dealumination plays a significant role during template removal. Other methods for the synthesis of mesoporous aluminum-containing sieves are based on the structural transformation of kanemite, and on cluster precursors which may be connected by self-condensation or by condensation with silicate bridges. Purely aluminous mesostructures can be prepared with neutral templates or by condensing Keggin-like aluminum clusters in an ordered salt with an anionic surfactant.

24 citations


Journal ArticleDOI
TL;DR: The nanoscale structure and synthesis mechanisms of the MCM-41 class of inorganic mesoporous materials have been investigated by small angle neutron scattering (SANS) measurements with solvents imbibed in the pores to vary the scattering contrast as discussed by the authors.
Abstract: The nanoscale structure and synthesis mechanisms of the MCM-41 class of inorganic mesoporous materials have been investigated by small angle neutron scattering (SANS). SANS measurements with solvents imbibed in the pores to vary the scattering contrast demonstrate that the low angle diffraction peaks from these materials are entirely due to the pore structure and that the pores are fully accessible to both aqueous and organic solvents. Static and shear flow SANS measurements on the concentrated cationic surfactant and silicate precursor solutions typically used in the synthesis of the mesopore materials indicate that the existence of preassembled supramolecular arrays that mimic the final pore structure is not essential for the synthesis of these materials.

24 citations


Journal ArticleDOI
TL;DR: In this paper, the fundamental friction properties of Woodceramics in sliding contact with several materials were described. But they did not consider the effect of sliding velocities on the friction coefficient.
Abstract: Woodceramics are new porous carbon materials obtained from wood or woody materials impregnated with phenol resin, and carbonized in a vacuum furnace at high temperature. Woodceramics have several superior characteristics from the viewpoints of engineering materials and ecological materials: they are hard and strong, have porous structure and low density, are made from natural resources, do not cause environmental pollution, and are cheap to manufacture. This paper describes the fundamental friction properties of Woodceramics in sliding contact with several materials. Woodceramics made of medium density fiberboard (MDF) and beech impregnated with phenol resin and carbonized in a vacuum furnace at 800°C and 2000°C were rubbed against alumina, silicon nitride, bearing steel and diamond by using a reciprocating friction apparatus. Experiments were carried out unlubricated in air, impregnated with base oil and in water, at several normal loads and sliding velocities. The following principal results were obtained: (1) The friction coefficient is around 0.15, under all three lubrication conditions; (2) The friction coefficient slightly decreases and then stays constant with increasing normal load; (3) The friction coefficient is not affected by sliding velocity; (4) Woodceramics have a good self-lubricity.

Journal ArticleDOI
TL;DR: In this paper, the Dubinin-Astakhov equation is applied to analyze high pressure CO2 adsorption at 273 K to characterize two sets of microporous carbons.
Abstract: The characterization of the pore structure of microporous materials is of interest because of the usefulness of these materials in many applications. Of these, the characterization of carbon adsorbents is particularly problematic because of the presence of small pores with size on the order of small molecules (micropores) along with a wide distribution of pore sizes, and their non-crystalline structure. In this paper, we present results obtained using the Dubinin-Astakhov equation to analyze data from high pressure CO2 adsorption at 273 K to characterize two sets of microporous carbons. Our results support the conclusions of previous workers that the Dubinin-Astakhov (DA) equation is able to linearize adsorption data that gives rise to curved Dubinin-Radushkevich plots. However, when applied over different ranges of relative pressure on the adsorption isotherm, the Dubinin-Astakhov plots result in different values of micropore volume and characteristic adsorption potential. Furthermore, DA analysis of CO2 (273 K) adsorption data over a wide range of pressures (10−3–22000 Tort), gives results different from DA analysis of CO2 (273 K) isotherms measured at low pressures only (10−3–830 Tort). It would appear desirable to apply the DA equation to data that reflects the entire range of micropore filling on the adsorption isotherm, as opposed to data over a limited relative pressure range. For CO2 adsorption at 273 K, this would necessitate adsorption studies at high pressures, to about 28 atm. Micropore volumes obtained in this manner, agreed with the total pore volumes determined by nitrogen (77 K) adsorption for all the activated carbons studied.

Journal ArticleDOI
TL;DR: In this paper, a conventional hydrothermal treatment with various concentrations of NaOH was used at 150° and 190°C to dissolve excess silica glass and thus make porous mullite ceramics from a fired New Zealand kaolin body.
Abstract: A conventional hydrothermal treatment with various concentrations of NaOH was used at 150° and 190°C to dissolve excess silica glass and thus make porous mullite ceramics from a fired New Zealand kaolin body. The effect of hydrothermal treatment time on the dissolution of the glass was examined. At 150°C, the dissolution of glass was almost complete after treatment for 8 hrs in 5N-NaOH solution and about 40–43 wt% of the glass was removed from the fired kaolin body leading to porous mullite. However, when the fired kaolin body was treated for more than 5 hrs in 5N-NaOH at 190°C, a composite of mullite and a nonporous crystalline phase of unknown symmetry resulted. These crystals formed from the dissolution and recrystallization of the glass. After the dissolution of glass in 2N-NaOH solution at 190°C for 5 hrs, a porous mullite body of 52.8% porosity with an average pore diameter of 0.57 μm could be obtained, and this was only composed of mullite whiskers. Growth of unidentified nonporous crystals in the body which was treated in 5N-NaOH solution at 190°C led to a decrease in specific surface area and therefore, these crystals should be avoided.

Journal ArticleDOI
TL;DR: The composite Zirfon® membranes are made of a polysulfone network and zirconium oxide as an inorganic filler as mentioned in this paper, and they are actually being used for a variety of ultrafiltration purposes and as separator material in different types of electrochemical cells.
Abstract: The composite Zirfon® membranes are made of a polysulfone network and zirconium oxide as an inorganic filler. These composite membranes are actually being used for a variety of ultrafiltration purposes and as separator material in different types of electrochemical cells.

Journal ArticleDOI
TL;DR: In this paper, the preparation and characterisation of nanometer-sized TiO2, CdO, and ZnO semiconductor particles trapped in zeolite NaY was carried out via the traditional ion exchange method and subsequent calcination procedure.
Abstract: In this paper, we report the preparation and characterisation of nanometer-sized TiO2, CdO, and ZnO semiconductor particles trapped in zeolite NaY. Preparation of these particles was carried out via the traditional ion exchange method and subsequent calcination procedure. It was found that the smaller cations, i.e., Cd2+ and Zn2+ could be readily introduced into the SI′ and SII′ sites located in the sodalite cages, through ion exchange; while this is not the case for the larger Ti species, i.e., Ti monomer [TiO]2+ or dimer [Ti2O3]2+ which were predominantly dispersed on the external surface of zeolite NaY. The subsequent calcination procedure promoted these Ti species to migrate into the internal surface of the supercages. These semiconductor particles confined in NaY zeolite host exhibited a significant blue shift in the UV-VIS absorption spectra, in contrast to the respective bulk semiconductor materials, due to the quantum size effect (QSE). The particle sizes calculated from the UV-VIS optical absorption spectra using the effective mass approximation model are in good agreement with the atomic absorption data.

Journal ArticleDOI
TL;DR: The hydroxyl group and water contents of alumina, mullite and alumino(boro)silicate gels and porous glasses (xerogels) are discussed on the basis of thermogravimetric, gas adsorption and density measurements as discussed by the authors.
Abstract: The hydroxyl group and water contents of alumina, mullite and alumino(boro)silicate gels and porous glasses (xerogels) are discussed on the basis of thermogravimetric, gas adsorption and density measurements. Comparison is made for powder prepared by instant hydrolysis and optically clear monoliths by slow hydrolysis, heated in various atmospheres (air, vacuum, hydrogen). The hydroxyl content appears to depend on the Al/Si ratio: 6 OH−/nm2 for alumina mesoporous glasses, 2 OH−/nm2 for aluminosilicate mesoporous glasses and 3 OH−/nm2 for microporous ones, typically.

Journal ArticleDOI
TL;DR: In this paper, the effect of burning temperature on Young's modulus and bending strength of beech wood has been investigated with a special reference to the effect on their bending Young's this paper.
Abstract: The mechanical properties of Woodceramics which were made from medium-density fiberboard have been investigated with special reference to the effect of burning temperature on their bending Young's modulus and bending strength. Woodceramics made from beech wood have also been tested to clarify the compressive strength anisotropy, and the role of phenol resin impregnation in strengthening the beech based charcoal. The bending Young's modulus hardly varies for burning temperatures between 300 and 500°C, but it improves remarkably for burning temperatures between 500 and 800°C. The bending strength degrades with temperature for burning temperatures between 300 and 500°C, but it improves remarkably with increasing temperature of burning between 500 and 800°C. The bending Young's modulus and bending strength gradually degrade with temperature for burning temperatures at and above 2000°C. The compressive strength of beech wood burned at 800°C in the longitudinal direction is greater than that in the radial direction, which in turn is greater than that in the tangential direction; this reflects the anisotropy of wood. Woodceramics made from beech wood have a compressive strength superior to beech charcoal in any of the following three directions: 4.5 times in the longitudinal direction, 3.4 times in the radial direction, and 2.0 times in the tangential direction. Both for beech charcoal and beech Woodceramics, brittle fracture is brought about by the buckling of cell wall in compression along the longitudinal direction but by the bending of cell wall in the compression along radial and tangential direction.

Journal ArticleDOI
TL;DR: In this paper, the effects of nucleation density on final membrane structure were investigated by changing dissolution temperature (T d, the temperature at which the melt-blend is formed) and polymer concentration in the initial polymer-diluent mixture.
Abstract: Poly(phenylene sulfide) (PPS) membranes were formed via solid-liquid thermally induced phase separation. The effects of nucleation density (η) on final membrane structure were investigated. η was varied by changing dissolution temperature (T d, the temperature at which the melt-blend is formed) and polymer concentration in the initial polymer-diluent mixture.

Journal ArticleDOI
TL;DR: In this paper, the effect of burning temperature on the structural changes of woodceramics is analyzed experimentally using medium density fiberboard which was burned at temperatures less than 1000°C in a charcoal kiln.
Abstract: Woodceramics are new porous carbon materials obtained by burning wood or woody material impregnated with thermosetting resin in a vacuum furnace. In this paper, the effect of burning temperature on the structural changes of Woodceramics is analyzed experimentally. Woodceramics were prepared using medium density fiberboard which was burned at temperatures less than 1000°C in a charcoal kiln. A drastic decrease in dimensions and weight was observed at temperatures lower than 600°C but they decreased gradually at temperatures higher than 600°C. Reproducibility of dimensions and weight by burning is possible. When Woodceramics were prepared by burning at higher than 1600°C by high frequency induction furnace, dimensions and weight decreased due to transformation of amorphous carbon to graphite, but the porous structure of wood remains unchanged. The distribution of glassy carbon and amorphous carbon was difficult to decipher after graphitization by observation with SEM and X-ray diffraction analysis.

Journal ArticleDOI
TL;DR: In this paper, the pore connectivity of amorphous aluminosilicates was investigated for textural evaluation, and it was shown that the connectivity is a function of the pH of synthesis.
Abstract: Amorphous aluminosilicates prepared by three different sol-gel procedures were submitted to N2-adsorption for textural evaluation. For each sample series, deviation of the experimental results from the ideal pore model imposed by the Kelvin equation was investigated, providing additional information on the pore architecture and specifically, on the degree of pore connectivity. This was verified by performing a similar statistical analysis for MCM-type materials. For amorphous aluminosilicates, the pore connectivity is shown to be a function of the pH of synthesis. The different cracking behaviour during drying of silicas and aluminosilicates prepared with organic additives could also be related to the various degrees of pore connectivity. In the second part of the article, a criterion for the applicability of the T-plot analysis for mixed micro-mesoporous products was searched for. Results indicate that when the micropores cover more than 20% of the total pore volume, reliable analyses are obtained by calculating the mean intercept for a T-layer thickness going from 2 to 9 A.

Journal ArticleDOI
TL;DR: In this paper, the morphology and local distribution of coke in biporous granules coked with a mixture of propane and butane under both kinetic and diffusion regimes were studied.
Abstract: Morphology and local distribution of coke is studied in γ-Al2O3 biporous granules coked with mixture of propane and butane under kinetic and diffusion regimes. Under kinetic regime atT 923 K, coke precipitates mainly on the surface of aggregates of the catalyst initial particles. The models and analytical relations are suggested for the analysis of coke distribution.

Journal ArticleDOI
TL;DR: In this paper, the fundamental wear properties of new porous carbon materials (Woodceramics) were analyzed by sliding an alumina ball (R=1.5, 4.0 mm) or hemispherical diamond pin (R =0.075 mm) against a Woodceramic plate (MDF-800), under three lubrication conditions: unlubricated in air, impregnated with base oil, and in water.
Abstract: The purpose of this investigation was to analyze the fundamental wear properties of new porous carbon materials “Woodceramics”. Wear tests were carried out by sliding an alumina ball (R=1.5, 4.0 mm) or hemispherical diamond pin (R=0.075 mm) against a Woodceramics plate (MDF-800), under three lubrication conditions: unlubricated in air, impregnated with base oil, and in water. The specific wear rate was calculated from the profile of the worn surfaces, and the relationship between the specific wear rate and the contact pressure parameter (W/R2)1/3 was obtained. Worn surfaces were observed with a scanning electron microscope (SEM) to clarify the microscopic wear mechanisms. The following principal results were obtained: (1) The specific wear rate of Woodceramics increases rapidly with increasing contact pressure parameter (W/R2)1/3, under all lubricated conditions; (2) When the contact pressure parameter (W/R2)1/3 is less than a certain critical value, the specific wear rate of Woodceramics is less than 10−8 [mm2/N], which is low enough for practical use; (3) The wear mode of Woodceramics can be classified into the following three modes: large-scale brittle fracture-induced wear (flake formation), small-scale brittle fracture-induced wear (powder formation), and ultra mild wear (ploughing).

Journal ArticleDOI
TL;DR: In this article, a microwave-hydrothermal treatment with 1 and 5N-NaOH solution was used at 150°C and 190°C to dissolve excess silica glass and thus make porous mullite ceramics from a fired New Zealand kaolin honeycomb.
Abstract: A microwave-hydrothermal treatment with 1 and 5N-NaOH solution was used at 150°C and 190°C to dissolve excess silica glass and thus make porous mullite ceramics from a fired New Zealand kaolin honeycomb. The effect of microwave-hydrothermal (M-H) treatment time on the dissolution of the glass was examined and compared to the result of conventional-hydrothermal (C-H) treatment. As expected, the rate of the dissolution of glass was faster with M-H treatment compared to C-H treatment. The dissolution of 40–43% glass was almost complete after M-H treatment in 1N-NaOH for 6 hrs at 150°C, in1N-NaOH for 3 hrs at 190°C, in5N-NaOH for 1.5 hrs at 150°C, and in 5N-NaOH for 35 minutes at 190°C. When the M-H treatment in 5N-NaOH solution at 190°C was more than 45 minutes, nonporous prismatic crystals were formed on the honeycomb and these crystals decreased the specific surface area. There were no changes in the morphology of mullite whiskers or in the structure of porous mullite body after M-H treatments in NaOH solutions compared to that of C-H treatment. The M-H treatment has been shown to be a rapid technique to prepare porous mullite ceramics from fired kaolin honey comb.

Journal ArticleDOI
N. Maes1, I. Heylen1, Pegie Cool1, M. De Bock1, C. Vanhoof1, Etienne F. Vansant1 
TL;DR: In this article, the porosity of two types of pillared clays, Al- and Ti-PILC, was investigated and the potential of these clays as adsorbents to be used as substituents or complements for zeolites was found.
Abstract: Fillared clays have become a well known class of porous materials. Due to the versatile porosity they seem to be complementary to zeolites and can be very useful for adsorption and catalytic processes. Despite intensive research, real industrial applications are still lacking. Somehow, the porosity of these pillared clays is not what was expected. The present study reports theoretical calculations, based on simple geometrical models in combination with experimental data, in order to obtain a better insight in the PILC structure and its limiting factors. Parameters such as interpillar free distance and maximum micropore volume were calculated and compared to experimental or literature data. The final goal is to find out the potential of pillared clays as adsorbents to be used as substituents or complements for zeolites. This part reports calculations, in terms of microporosity, performed for two types of pillared clays having completely different porosity properties: Al- and Ti-PILC.

Journal ArticleDOI
TL;DR: In this paper, the effects of calcining conditions of kaolinite on pore structures of the porous materials obtained from the selective leaching of calcined calcined KOLA using KOH solution were described.
Abstract: This paper describes the effects of calcining conditions of kaolinite on pore structures of the porous materials obtained from the selective leaching of calcined kaolinite using KOH solution. Mesoporous γ-Al2O3 was the predominant crystalline phase in the samples calcined in the temperature range between 950°C and 1050°C for 24 h. The mean specific surface area of these samples was approximately 250 m2 · g−1 and the mean total pore volume was approximately 0.8 ml · g−1. The pore size distribution curves of these samples showed a sharp peak at around 2–3 nm pore radius. This peak was sharper for the sample calcined at 1000°C for 24 h. On the other hand, the pore sizes of the sample calcined at 1100°C for 24 h increased abruptly to 10–20 nm and this change corresponded to the formation of mullite in the sample. The pore sizes of the samples calcined at 1100°C varied with calcining time. The specific surface area and total pore volume decreased, the longer the calcining time of the samples, and this was correlated with an increase in the amount of mullite in the samples.

Journal ArticleDOI
TL;DR: In this paper, two mesoporous silica molecular sieves, one synthesized by cationic template method and another by neutral template route, were characterized for their pore-size distribution by a novel Temperature-Programmed Desorption (TPD) method and the widely used N2 desorption method.
Abstract: Two mesoporous silica molecular sieves, one synthesized by cationic template method and another by neutral template route, were characterized for their pore-size distribution by a novel Temperature-Programmed Desorption (TPD) method and the widely used N2 desorption method. The pore-size distributions determined by the two methods agree quite well and are within experimental errors. For example, TPD method gave a pore size distribution (radius) centered at 14 A while N2 desorption method showed a peak centered at 13.3 A. for the mesoporous silica prepared by cationic template route. The new TPD method based on thermogravimetric analysis is a viable option for mesopore characterization of silica-based materials.

Journal ArticleDOI
Ilse Heylen1, N. Maes1, Pegie Cool1, M. De Bock1, Etienne F. Vansant1 
TL;DR: In this paper, a better understanding of the potential and limiting factors of mixed Fe and mixed Fe-Zr pillared clays is focused by theoretical modelling calculations including interlayer distance, pillar symmetry, collapse and partial pillaring.
Abstract: Pillared clays are proposed as a new class of sorbents with properties similar to zeolites. However, despite extensive research, zeolites have not yet been replaced by pillared clays for industrial applications. In the present study a better understanding of the potential and limiting factors of Fe and mixed Fe-Zr pillared clays is focused by theoretical modelling calculations including interlayer distance, pillar symmetry, collapse and partial pillaring. The results are evaluated on microporosity and interpillar distance and are compared to experimental data.

Journal ArticleDOI
TL;DR: In this article, the changes in the texture characteristics of catalysts, adsorbents, supports and other porous bodies are analyzed, upon the partial filling of their voids with the added components: coke, sulfur, active components of supported catalysts.
Abstract: The changes in the main texture characteristics of catalysts, adsorbents, supports and other porous bodies are analyzed, upon the partial filling of their voids with the added components: coke, sulfur, active components of supported catalysts, etc. Equations are derived, that relate the changes of texture with the content and distribution of the introduced component.

Journal ArticleDOI
TL;DR: In this paper, quaternary ammonium salts with the formula (C16H33, CnH2n+1), CH3)2N+Br (n = 1 to 12) have been synthesized and used as templates to prepare crystalline mesoporous molecular sieves.
Abstract: New quaternary ammonium salts with the formula, (C16H33)(CnH2n+1)(CH3)2N+Br (n =1 to 12) have been synthesized and used as templates to prepare crystalline mesoporous molecular sieves The effect of the CnH2n+1 chain length on the nature of the obtained product and its d-distance has been investigated A correlation between the nature of the obtained phases and the conformation of the carbon chain of the occluded surfactant was revealed by13C CP MAS NMR

Journal ArticleDOI
TL;DR: In this article, butanolic zirconium(IV) tetra-n-butoxide diluted in ethanol via stoichiometric hydrolysis with water in ethanol was used to modify the sol-gel process.
Abstract: Zirconia aerogels have been prepared from butanolic zirconium(IV) tetra-n-butoxide diluted in ethanol via stoichiometric hydrolysis with water in ethanol. Nitric acid or acetic acid were used to modify the sol-gel process. After calcination in air at 573 K, the aerogel prepared with nitric acid possesses a specific surface area of 240 m2 · g−1 and a unimodal pore size distribution with a maximum at ca. 24 nm, whereas the use of acetic acid results in an aerogel with specific surface area of 228 m2 · g−1 and bimodal pore size distribution with maxima at 3 and 65 nm. The crystalline fractions of both aerogels are predominantly tetragonal with a small contribution of monoclinic ZrO2.