V. B. Fenelonov

Mesopore size and surface area calculations for hexagonal mesophases (types MCM-41, FSM-16, etc.) using low-angle XRD and adsorption data

This paper is devoted to the geometry of mesoporous mesophase systems (MMSs) of the MCM-41 or FSM-16 texture types. The interrelations among surface areas inside and outside the mesoporous blocks of the MMS, of the size and the volume of mesopores are discussed. The equations for calculating these textural characteristics are derived. These equations are based on adsorption data and X-ray diffraction studies, and are applied for considerations of the silica and zirconia hexagonal MMS texture. The approach was used for a critical review of the results published by other authors for similar systems.

Porous carbon materials prepared from C1–C3 hydrocarbons

Abstract The inexhaustibility of various solid porous carbons produced from C1–C3 hydrocarbons, which may be used as catalyst supports, adsorbents and so on is reported.

Comparative textural study of highly ordered silicate and aluminosilicate mesoporous mesophase materials having different pore sizes

Abstract Honeycomb structure model was applied for describing surface properties in the MCM-41 and SBA-15 types of highly ordered silicas and aluminosilicates with different nominal mesopore diameters: about 4 nm and about 10 nm. As shown, calculations of internal specific surface area A me require a heterogeneity of this surface to be taken into account, the latter being quantified by the roughness coefficient β . These calculations at the condition β =1.0 will allow to estimate the lower limit of specific surface area of the materials only, which will correspond to the perfectly smooth walls of mesopores. This description seems to be valid for the MCM-41 type systems, for which β is about 1.1–1.2. On the contrary, β is found to exceed 1.5 for the SBA-15 type materials. This fact is probably due to an essential non-smoothness of the mesopore surface in these systems and may be associated with their synthesis conditions.

Texture and adsorptive properties of microporous amorphous carbon materials prepared by the chemical activation of carbonized high-ash biomass

Samples of microporous amorphous carbon materials with calculated BET specific surface areas of up to 3500 m2/g, pore volumes of up to 3.0 cm3/g, and micropore volumes of up to 1.9 cm3/g were prepared using the chemical activation of rice hulls carbonized in a fluidized-bed reactor with a copper-chromium catalyst for deep oxidation. The effects of various activation parameters (temperature, activating agents, etc.) were studied, and optimum parameters were chosen. The resulting materials exhibited sorption capacities of up to 6.3 and 41 wt % for hydrogen at liquid nitrogen temperature and 50 atm and for methane at 0°C and 60 atm, respectively. Because of this, they are promising for use in the purification, storage, and transportation of fuel gases. Moreover, some aspects of the mechanism of the interaction of an activating agent with a carbon-containing precursor are proposed.

Cu, Co, Ag-Containing Pillared Clays as Catalysts for the Selective Reduction of NOx by Hydrocarbons in an Excess of Oxygen

Thermally stable Al- and Zr-PILC loaded with copper and cobalt cations and silver nanoparticles were synthesized. The structural and surface features of these nanosystems were studied and compared with those of bulk analogs – partially stabilized ZrO2 loaded with the same active components. Specificity of the catalytic properties of nanocomposites in SCR of NOx by propane, propylene and decane in the excess of oxygen appears to be determined both by distribution of active components on the catalytic surface and degree of their interaction with supports. Formation of ads.-NOx, nitroxyl-hydrocarbon CxHyNO2⋅ and isocyanate NCO intermediates was observed by ESR and IR spectroscopy in situ.

The three-dimensional microporous structure of alumina synthesized through the aluminum hydrothermal oxidation route

The structural properties and porosity of a γ-alumina sample prepared by the hydrothermal treatment of powdered aluminum were investigated using techniques of nitrogen adsorption, mercury porosimetry, and electron microscopy. The information available from each technique is used to present a more complete picture of the three-dimensional pore structure of this sample, in terms of size, shape, distribution, crystallographic orientation and accessibility of pores.

Mesoporous basic zirconium sulfate: structure, acidic properties and catalytic behaviour

Abstract Some properties of a thermostable mesophase of basic zirconium sulfate with texture characteristics close to those of MCM-41 are described. After calcination at 550 °C the mesophase exhibits a specific surface area of mesopores of 450–500 m2g−1. The peculiarities of the catalytic behavior of the mesophase are related to its acidic properties.

A Sol–Gel Derived CuOx/Al2O3–ZrO2 Catalyst for the Selective Reduction of NO by Propane in the Presence of Excess Oxygen

Copper catalysts supported on alumina-doped zirconia were prepared by sol–gel processing followed by supercritical drying or aging in the mother solution at 100 °C. After drying and calcination, the catalyst supports were impregnated with a copper(II) nitrate aqueous solution by the incipient wetness method to achieve a Cu loading of about 2%. The samples showed ∼90% NO conversion at 350–400 °C. The catalytic performance of these systems appears to be determined by the degree of clustering of copper cations as probed by FTIR spectroscopy of adsorbed CO.

Characterization of the Porous Structure of Carbon Materials by Means of Density Functional Theory

Nitrogen adsorption isotherms were analyzed using density functional theory (DFT) to characterize active carbons. It is shown how the effect of technological parameters on the structure of active carbons can be revealed with the help of DFT. DFT is used to analyze the pore-size distribution and to determine the pore surface area for active carbons of different types.

Coke dispersion in carbon–mineral porous adsorbents

Abstract The morphology, dispersion and localization of coke in coked alumina and silica have been investigated by a newly developed technique, which can be applied generally for studies of other systems of ‘support+modifier’ type. It is shown that, at the considered amounts of coke, deposited coke clusters partially cover the surface of silica leading to a mosaic-like structure of the resulting carbon–mineral material surface. These clusters are predominantly located in the pores of silica gel. Probably the pores filled with coke are formed by the tetrahedron packed SiO2 globules. On the other hand, the intensity of coke formation on the alumina surface is considerably higher then on the silica surface, so coke formation is accompanied by the total surface coverage at low amounts of coke deposited. Possible reasons for these differences are considered.