Influence of alkaline modification on adsorption properties of alumina

The kinetics of water vapor adsorption on alumina adsorbents at a temperature of 25 °C was studied. It was shown that modification by cations of alkali metals (K, Na) of the adsorbent based on alumina allows increasing its efficiency in the process of water vapor adsorption. The mathematical treatment of the experimental data by the dependence of water vapor adsorption on the time with the help of the Linear Driving Force (LDF) model and the dependence of adsorbent's adsorption capacity on the water vapor concentration (adsorption isotherm) by Dubinin-Astakhov equation was carried out. Constants included in the equations were defined

Aluminium oxide-hydroxides obtained by hydrothermal synthesis: influence of thermal treatment on phase composition and textural characteristics

Aluminium oxide-hydroxides obtained by means of the hydrothermal synthesis of aluminium nanopowder are of great interest in terms of the potential supports for heterogeneous catalysts due its high specific surface area (200...300 m2/g) and pore size of 4...17 nm. In this work the influence of thermal treatment (150...1300 °C) on structural and phase composition, specific surface area and porosity of aluminium oxide-hydroxides has been investigated. Nanostructured γ-Al2O3 (T=400 °C) was found to have the specific surface area of 328 m2/g and average pore size of ~9 nm. The thermal treatment of aluminium oxide- hydroxides at the temperature of higher and lower than 400 °C has caused the reduction of specific surface area and overall pore volume

Cr2O3/Al-Al2O3 composite catalysts for hydrocarbons dehydrogenation prepared from aluminum nanopowder

Aluminum nanopowder (10–150 nm) was treated hydrothermally in mild conditions (60–95 °C, at atmospheric pressure), and an aluminum-alumina composite with high porosity and specific surface area was obtained. Cr2O3/Al-Al2O3 catalysts were prepared using the aluminum-alumina composite by impregnation techniques and tested in dehydrogenation of C4-hydrocarbons. It was shown that aluminum-alumina composites had high chemical and phase purity, specific surface area of 150–350 m2/g and the average pore size of 8–13 nm, that is favorable for application as support for catalysts. Cr2O3/Al-Al2O3 catalysts had high activity and selectivity in dehydrogenation of n- and i-butane (conversion of 44–80 mol.% and selectivity >85% at temperatures of 540–610 °C), that is comparable ones for commercial catalysts for CATOFIN, STAR processes

Effect of particle size on adsorption kinetics of water vapor on porous aluminium oxide material

Influence of the grain size of aluminium oxide material, being a product of centrifugal thermal activation of hydrargillite, on adsorption kinetics of water vapors was studied. The material was characterized by the BET method and X-ray phase analysis (XRD). Influence of gas flow rate on adsorption dynamics was studied on a laboratory installation using McBain-Bakr quartz balance. It was shown that with the fraction size greater than 0.5-1.0 mm, the rate of water vapor adsorption on this adsorbent decreased, which was connected with the influence of internal diffusion resistance. On the base of the first-order kinetic equation for the water adsorption mathematical modeling was carried out. The kinetic parameters of the equation for the various grain size samples (0.25-0.5 mm and 0.5-1.0 mm and 3.7 x 6 mm granule) were determined

Theoretical optimization of the shape and size of adsorbent grains for associated petroleum gas drying

The shape of adsorbent grains used for drying hydrocarbon gas flows at a reduced hydraulic resistance of their beds are theoretically optimized. A two-velocity model of gas flow in fixed beds consisting of differently shaped holed particles is used for calculations at typical parameters of the associated petroleum gas drying process. It is shown that the optimum shape of a grain is a four-spoke ring. At an equivalent diameter of 3 mm, such a grain is 6.154 × 6.154 mm in size, and its walls and baffles are 1.026 mm thick

Cr2O3/Al-Al2O3 composite catalysts for hydrocarbons dehydrogenation prepared from aluminum nanopowder

Aluminum nanopowder (10–150 nm) was treated hydrothermally in mild conditions (60–95 °C, at atmospheric pressure), and an aluminum-alumina composite with high porosity and specific surface area was obtained. Cr2O3/Al-Al2O3 catalysts were prepared using the aluminum-alumina composite by impregnation techniques and tested in dehydrogenation of C4-hydrocarbons. It was shown that aluminum-alumina composites had high chemical and phase purity, specific surface area of 150–350 m2/g and the average pore size of 8–13 nm, that is favorable for application as support for catalysts. Cr2O3/Al-Al2O3 catalysts had high activity and selectivity in dehydrogenation of n- and i-butane (conversion of 44–80 mol.% and selectivity >85% at temperatures of 540–610 °C), that is comparable ones for commercial catalysts for CATOFIN, STAR processes

Aluminium oxide-hydroxides obtained by hydrothermal synthesis: influence of thermal treatment on phase composition and textural characteristics

Aluminium oxide-hydroxides obtained by means of the hydrothermal synthesis of aluminium nanopowder are of great interest in terms of the potential supports for heterogeneous catalysts due its high specific surface area (200...300 m2/g) and pore size of 4...17 nm. In this work the influence of thermal treatment (150...1300 °C) on structural and phase composition, specific surface area and porosity of aluminium oxide-hydroxides has been investigated. Nanostructured γ-Al2O3 (T=400 °C) was found to have the specific surface area of 328 m2/g and average pore size of ~9 nm. The thermal treatment of aluminium oxide- hydroxides at the temperature of higher and lower than 400 °C has caused the reduction of specific surface area and overall pore volume

Theoretical optimization of the shape and size of adsorbent grains for associated petroleum gas drying

The shape of adsorbent grains used for drying hydrocarbon gas flows at a reduced hydraulic resistance of their beds are theoretically optimized. A two-velocity model of gas flow in fixed beds consisting of differently shaped holed particles is used for calculations at typical parameters of the associated petroleum gas drying process. It is shown that the optimum shape of a grain is a four-spoke ring. At an equivalent diameter of 3 mm, such a grain is 6.154 × 6.154 mm in size, and its walls and baffles are 1.026 mm thick