Interaction between the water adsorption ability of aluminium-oxide-based sorbents and their chemical composition, acid-base properties of the surface, and textural characteristics has been analysed. Alumina desiccants were synthesized with the centrifugal–thermal activation of gibbsite followed by the hydration of the gibbsite under mild conditions. It was demonstrated that the multicyclic adsorption regeneration of samples under realistic conditions results in structural transformations and changes in the acidity of their surfaces and water adsorption ability. The modification of pseudoboehmite with alkali ions increases surface basicity and the dynamic capacity of adsorbents relating to water vapours. Equations have been presented that describe the adsorption and desorption processes taking place during water vapour adsorption with the materials studied.

The effect of alkali metal (Li, Na, K) incorporation on the morphology and water vapor uptake properties of mesoporous Al2O3 has been studied. The modification of the raw material, pseudoboehmite, represented a mixture of low-temperature phases (γ + η + χ)-Al2O3, and has been done at low-temperature that does not change the phase ratio. A decrease in specific surface values and an average pores size increase were observed as a result of the introduction of metal cations by impregnation and subsequent thermal treatment. The influence of the content of the modifying metal on the adsorption ability of the obtained samples in relation to water vapours has been studied. It has been established that alkaline modification Al2O3 with the lithium cations did not result in adsorption ability improvement, whereas samples that were modified with sodium or potassium in the amount of 1.2 weight % and 2.6 weight %, respectively, possess a higher equilibrium capacity (by ~40%), as compared to that of the initial sample (Al2O3), and a sufficiently high adsorption rate.

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The dynamic capacity of the commercial desiccant (NaX zeolite) and the adsorbent, synthesised based on low-temperature modifications of aluminium oxide, obtained from bayerite-containing hydroxide, was determined with respect to water vapour. Experimental studies were carried out using a pilot installation at the atmospheric pressure and increased pressure (up to 0.6 MPa) and high humidity. The increase in the height of the layer of the adsorbents leads to an increase of their dynamic capacity with respect to water vapour and the protective power (action) time of the layer. It was shown that at the atmospheric pressure and the pressure of up to 0.3 MPa, the dynamic capacity of NaX is greater; at a higher pressure, the adsorption capacity of the developed adsorbent Al2O3 becomes greater than the zeolite capacity, which allows recommending it as a desiccant at increased pressure.