Systematic synthesis of zeolites that contain cubic and hexagonal stackings of faujasite sheets

Synthetic cubic faujasite (FAU) has been known for several decades, and it is one of the most studied and commercially important zeolites. Recently, the hexagonal polytype of faujasite has been synthesized by Delprato et al. We have subsequently confirmed the synthesis procedures to crystallize this new zeolite and have compared of its physicochemical properties to those of . Also, we have shown that the hexagonal polytype faujasite (for our purposes denoted as hex) can be by contact with SiCl_4 vapor in a manner to that used for the dealumination of FAU. The of the cubic and hexagonal polytypes of faujasite one to speculate on whether zeolites can be synthesized as intergrowths between these two end members any ratio of two polytype contents. ZSM-20 is an intergrowth of cubic and hexagonal stackings of faujasite , and ZSM-2, ZSM-3, and ZSM-19 may also be intergrowths. purpose of our work is to explore the possibility of zeolites that are comprised of intergrowths cubic and hexagonal stackings of faujasite sheets and in the ratio of cubic/hexagonal content. From Delprato al., pure hex and FAU can be synthesized from the reaction mixture R·2.4Na_2O·Al_O_3·10SiO_2·140H_2O, R is 1,4,7,10,13,16-hexaoxacyclooctadecane (18- -6) and 1,4,7,10,13-pentaoxacyclopentadecane (15- -5), respectively. Thus, in this work we use the reaction mixture (1 - x)R_1·xR_2·2.4Na_2O·Al_2O_3·10SiO_2• 140H_2O, where R_1 = 18-crown-6, R_2 = 15-crown-5, and x varied as 0 ≤ x ≤ 1.