Morphology-Controlled Synthesis of Zeolite and Physicochemical Properties

Abstract

Zeolite L is a crystalline aluminosilicate compound and a typical chemical composition of K9Al9Si27O72•nH2O (n = 0-36). The structure and chemical properties, as well as their sizes and morphologies of zeolite L has led to various applications in different fields. The aim of this study is to investigate the effects of chemical compositions of the starting gel on the synthesis, size and morphology of zeolite L crystals. Zeolite L had been synthesized hydrothermally at 180 ˚C for 2 days, from gels with the molar compositions of 2.62-3.78 K2O: 0.8-1.4 Al2O3: 8-12 SiO2: 80-200 H2O. The variation of chemical compositions led to the differences in morphologies and crystal sizes. Their morphologies varied from ice hockey to cylindrical shapes and their crystal sizes varying from 1.50-7.53 µm. With an increase in H2O and SiO2, the crystal size was also increased but decreased with an increase in K2O. In varying Al2O3, there was no effect on their shapes which were still cylindrical but with different crystal sizes. Moreover, the adsorption of ethylene on zeolite L samples depended significantly on crystal shapes and sizes.

Selective Chlorination of Toluene to <I>p</I>-Chlorotoluene Catalyzed by Nanosized Zeolite K-L Catalysts

“…With increasing the autoclaving times to 72-120 h, strong XRD peaks ascribed to zeolite K-L were observed, indicating that well-crystallized zeolite K-L samples were synthesized. [21][22][23] When the mole ratio of SiO 2 to Al 2 O 3 was increased to 31:1, the appearance of strong XRD peaks indicated that well-crystallized zeolite K-L samples were synthesized. From the low-angle X-ray diffraction spectra, it was also found that when the samples were synthesized with the mole ratio of SiO 2 to Al 2 O 3 of 21:1, weak characteristic peaks of zeolite K-L appeared at 2 = 5 5 .…”

“…Generally, the silica content in zeolite K-L sample slightly increased with increasing the mole ratio of SiO 2 to Al 2 O 3 in the reaction solution. The formulas of the zeolite K-L samples were close to the ideal formula of zeolite K-L, K 9 Al 9 Si 27 O 72 · nH 2 O, especially, when the zeolite K-L samples were synthesized with high mole ratio of SiO 2 to Al 2 O 3 21. 24 25 …”

Determination of the influence of organic and inorganic impurity on physico-chemical properties of detergent zeolite type 4A

“…Ovaj rad prikazuje ispitivanja sintetičkog deterdžentskog zeolita tipa 4A dobijenog homogenom sintezom [1][2][3][4][5][6]. Zeoliti mogu da se sintetišu iz apsolutno čistih rastvora gdje se aluminat dobija rastvaranjem hidrata poznatih karakteristika u laboratorijskim uslovima i tada nema primjesa koje mogu biti unešene u konačni proizvod [7][8][9].…”

“…Potrebna je sljedeća količina filtrata: U polazne sirovine pripremljene kao u predhodnom primjeru dodata je potrebna količina Na 2 SO 4 ,dok su koncentracije preračunate na SO 4 2-(g/L). U dobijenom uzorku zeolita određen je gubitak žarenjem, pomoću njega jonoizmjenjivački kapacitet, zatim je mjerena kristaličnost i bjelina (Tabela 3, Slike 4,5).…”

“…Nakon sintetisanja zeolita bez primjesa izvršene su sinteza sa dodacima organskih i neorganskih mikroprimjesa. Dobre osobine ima zeolit koji je sintetisan sa najmanjom količinom dodatih SO 4 2-jona, dok i pri dodatku 0.010 i 0.021 g/L CaO karakteristike dobijenog zeolita ostaju veoma dobre. Tek kada se doda duplo veća količina primjesa, kvalitet zeolita se značajno smanjuje, što se vidi po slabom jonoizmjenjivačkom kapacitetu kao i smanjenoj kristaličnosti.…”