Influence of the temperature of calcination of bayerite-containing aluminum hydroxide pellets on the water vapor adsorption capacity and acid-base properties of alumina

Characteristics optimization of activated alumina desiccants based on product of a centrifugal thermal activation of gibbsite

“…Measurements were made in an adsorber with diameter of 30 mm and height of 400 mm under the following conditions: (1) at low moisture content in the gas at the adsorber inlet: 0.86 g H 2 O/m 3 (dew point -18.7°C); rate of the vapor-air mixture, 3.4 L min -1 ; gas temperature 22°C; adsorbent charge 100 cm 3 ; (2) at high moisture content of the gas at the adsorber inlet: 15.6-16.6 g H 2 O/m 3 (dew point 18. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].5°C) fl ow rate of the vapor-air mixture, 4.1 L min -1 ; atmospheric pressure; gas temperature 22°C; adsorbent charge 120 cm 3 .…”

“…The drying agent is produced by the ecologically safe technique of centrifugal thermal activation of gibbsite (CTA G), followed by hydration of the CTA G product to bayerite under mild conditions [5,6]. The static capacity of desiccants of this kind at a relative humidity of 60% reached a value of 24.2 g H 2 O/100 g of drying agent, and the dynamic capacity (dew point -40°C) was as high as 8.2 g H 2 O/100 g of drying agent or 5.07 g of H 2 O per 100 cm3 of AAD.…”

Influence of the Composition, Structure, and Physical and Chemical Properties of Aluminium-Oxide-Based Sorbents on Water Adsorption Ability

“…There are studies on highly effective alumina desiccant adsorbents based on low-temperature forms of aluminium oxide (η-, γ-, and χ-) received by means of the incineration of alkaline hydration products of thermally activated alumina containing bayerite phases of 50% and more [ 2 , 5 , 6 ]. A characteristic of bayerite-containing hydroxide is the formation of low-temperature phases of aluminium oxide (first, η-modification) at a calcination temperature >300 °С.…”

“…A characteristic of bayerite-containing hydroxide is the formation of low-temperature phases of aluminium oxide (first, η-modification) at a calcination temperature >300 °С. This provides an opportunity to obtain samples with a developed specific surface area, the required combination of surface sites, a large quantity of micropores, and therefore a larger static capacity than that of the desiccants based on γ-Al 2 O 3 that are obtained on the basis of pseudoboehmite using the reprecipitation method [ 5 ]. The study [ 6 ] demonstrated that the dynamic capacity of pseudoboehmite-based desiccants synthesized with the centrifugal–thermal activation of gibbsite with its subsequent hydration under mild conditions is significantly lower than the dynamic capacity of desiccants based on η-Al 2 O 3 .…”

“…This is related to change in phase composition, textural characteristics, and acid–base surface properties. Moreover, a greater modifying effect was observed in desiccants based on γ-Al 2 O 3 that had a greater quantity of Bronsted acid sites (BAS) and potent Lewis acid sites (LAS) after the introduction of sulphate ions, and the average diameter of pores was reduced [ 5 ]. The dependence of the static capacity value at low relative humidity on the concentration of electron-withdrawing sites has been established.…”