# Efficient Adsorbent-Desiccant Based on Aluminium Oxide
## 6 Conclusions  
The abovementioned method of thermal activation of gibbsite (TCA Gb) has a number of economic and environmental advantages over traditional methods of reprecipitation and hydrolysis of aluminium alcoholates due to lower production costs and less waste. As a result of TCA, a product is obtained that is suitable for further processing into aluminium hydroxides, from which, in turn, aluminium oxide adsorbents, carriers and catalysts can be synthesized. However, this method also has a number of disadvantages, mentioned in the review. A more promising method is its improved version--thermal activation of gibbsite powder for 1-2 s in contact with a rotating and heated solid heat carrier under the action of centrifugal forces in flash reactors (CTA Gb, TSEFLAR(tm)). The reduction of energy consumption and harmful emissions as compared to the TCA method is achieved by eliminating the use of combustion gases and intensifying the heat supply to the reagent layer due to the contact with a solid rotating surface.  
Based on the advantages and disadvantages of industrial adsorbents-desiccants mentioned in the review, it can be concluded that the main dehydration of gases with a significant water vapour content should be carried out with aluminium oxide, which is resistant to condensed moisture, and a deep final dehumidification with zeolite.  
Varying the conditions for the preparation of adsorbents-desiccants based on aluminium oxide and modifying them with the introduction of alkaline cations (Na and K) makes it possible to control the change in the characteristics of donor and acceptor active sites on the surface of adsorbents and thereby significantly increase their adsorption activity, in particular, with respect to water vapour. It has been shown that the preparation of adsorbents-desiccants based on \(\eta\)-Al\({}_{2}\)O\({}_{3}\) should rather be carried out by regulating the concentration of alkali at the stage of hydration of the thermal activation product during synthesis. This makes it possible to obtain adsorbents with high values of static and dynamic water vapour capacity and mechanical strength. The adsorption properties (adsorption rate and adsorption capacity) of adsorbents obtained by this method, with a sodium content of 2.3 mass.% (adsorption rate and adsorption capacity), are quite similar to the characteristics of the zeolite-based adsorbents, which are widely used for deep air dehumidification. In this way, such adsorbents have a good potential for industrial use not only as a protective layer, but also as a main layer.  
Conceptualization, E.P.M. and I.A.K.; methodology, S.I.R.; writing--original draft preparation, E.P.M.; writing--review and editing, E.P.M., S.I.R. and M.P.S.; visualization, M.P.S.; funding acquisition, I.A.K. and A.S.K. All authors have read and agreed to the published version of the manuscript.  
Funding: The work has been performed (Sections 1, 3 and 4) with the support of the Competitiveness Improvement Program of TSU (project 8.2.10.2018) and with the support of the Ministry of Science and Higher Education, project number 0721-2020-0037 (Sections 2, 5 and 6). Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: No new data were created or analyzed in this study. Data sharing is not applicable to this article. Conflicts of Interest: The authors declare no conflict of interest.