Study Of Texture And Sorbtion Properties Of High Silicone Zeolites Synthesed From Bentonite
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Abstract
The article proposes a method of synthesizing high-silicon zeolite on the basis of "zol-gel" technology by activating bentonite in Navbahor district of Uzbekistan by physical and chemical methods, and studied the physicochemical, texture and sorption characteristics of the samples.
According to the X-ray phase analysis, the samples had a zeolite-like crystalline phase with a ZSM-40 structure, and the relative crystallinity of the samples was calculated from a reflection area of 22–25 ° relative to the most crystallized sample in the series.
As a result of studying the effect of the temperature of "Zol-gel" synthesis on the size, texture and structure of the crystals of the synthesized sorbents, it was proved that the increase in temperature leads to an increase in the average size, texture and structure and crystallinity of samples .
In the adsorption isotherms of water: with the increase of the ratio of silicon, a gradual disappearance of hysteresis is observed, as a result of a decrease in the volume of mesocytes, the total volume of pores decreases with increasing crystal size to the total volume of pores between packaged crystals. water: as the silicon ratio increases, the outer surface area of zeolites first increases, water: reaches a maximum for a sample synthesized from a mixture of tetraethyl orthosilicate, bentonite, sodium hydroxide, ethyl alcohol, hexamethylenediamine and citric acid with silicon = 50, then decreases to a minimum . The transition of zeolites to the H-shape leads to the formation of strong acid fields and promotes the formation of high-temperature peaks in the thermo-programmed desorption curves of ammonia in the range of 425 - 440 ° C. For all zeolites, the concentration of strong acid fields is close and lies in the range of 0.05 - 0.1 mmol / g.
As a result of the research, methods of synthesis conditions were developed to find optimal conditions for the synthesis of a type of high-silicon zeolite sample of the required size and structure, as well as with improved texture characteristics .
Based on the values of the adsorption capacity of the samples and the approximation of the phenol molecule to occupy an area of 0.57 nm 2 , the surface occupied by phenol in the single-layer coating of the samples was evaluated.