Modification of NaY zeolite by citric acid through application of tensides

Abstract

The zeolites are popular group of minerals for collectors and important group of minerals for industrial and other purposes. They combine rarity, beauty, complexity and unique crystal habits. Typically forming in the cavities, or vesicles, of volcanic rocks, zeolites are the result of very low grade metamorphism. Some are formed from just subtle amounts of heat and pressure and can just barely be called metamorphic, while others are found in obviously metamorphic regimes. There is undergoing extensive research into the formation of zeolites and their unique properties. The NaY zeolite is analogue to the natural zeolite phosphazide and belongs to the IVth group according to the zeolite classification. The typical composition of NaY elementary cell is Na56[(AlO2)56(SiO2)136]·250H2O containing double hexagonal rings (D6R). This research was focused on a NaY zeolite, obtained by hydro-thermal procedure with a chosen oxide ratio: SiO2/Al2O3 = 9.0; Na2O/SiO2 = 0.33; H2O/Na2O = 40. The chemical composition of the starting mixture for the synthesis is determined by the chemical formula 2.97Na2O·Al2O3·9SiO2·118.8H2O. The dealumination process on the NaY zeolite was performed by application of citric acid with concentrations of 0.1 and 0.5 mol/dm3 and introduction of tensides (I, II, III, IV). Dealumination procedure is conducted in order to extract the most of the Al content from the zeolite structure while preserving the crystal structure, with crystalinity above 50%. NaY zeolite has a solid structure and therefore a dealumination process is required in order to modify this material into a suitable catalyst, as well as for other uses. Obtained products were analyzed by X-Ray, and DTA, TGA and DTG. The results of the performed dealumination are presented in tables. Crystalinity was determined as 56.90%, compared to the crystalinity of the commercial zeolite that has a reported crystalinity of 100%.