Transformation of Natural Analcime and Phillipsite During Their Hydrothermal Recrystallization Into Zeolites a and X.

Abstract

The objective of the present work was to study transformation of Georgian natural zeolites, analcime and phillipsite, during their recrystallization in the aim to obtain zeolites A and X, widely used for adsorption, separation, ion exchange and catalysis. It is found that phase-pure zeolite NaA (Na 11.25(25) (K,½Ca,½Mg) 0.7(1) (Al 11.95(25) Si 12.3(3) O 48). 18H 2 O) can be prepared in the form of cubic/rhombus crystallites with uniform micrometric (3-5 μm) dimensions by hydrothermal crystallization (95 o C) of aged (72 hr) at room temperature gel (4.5Na 2 O: 0.45Al 2 O 3 : 1SiO 2 : 178H 2 O) obtained from natural analcime, treated with hydrochloric acid before suspending in water and mixing with sodium hydroxide. Phase-pure zeolite NaX (|Na 66(3) [K,½Ca,½Mg,½Cu,½Zn] 12(1) (H 2 O) 248(10) | (Al 78(3) Si 114(4) O 384)) with specific surface area of 589 m 2 /g and total pore volume of 0.578 cm 3 /g can be prepared in the form of octahedral crystallites with uniform micrometric (2-7 μm) dimensions by hydrothermal crystallization (95 o C) of aged (96 hr) at room temperature gel (2.9Na 2 O: 0.26Al 2 O 3 : 1SiO 2 : 150H 2 O) obtained from water suspension of natural phillipsite, treated with hydrochloric acid and mixed with sodium hydroxide. The resulting zeolites in their characteristics are competitive with commercially available materials.