Effect of Li, Na and K Modification of Alumina on its Physical and Chemical Properties and Water Adsorption Ability.

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.