The influence of nature of the anion in tetraalkylammonium salts on the crystallization of zeolite beta

The influence of the nature of anion X in the tetraethylammonium salt [N(C2H5)4]X on the selectivity of the formation zeolite beta in the SiO2-Al2O3-Na2O-[N(C2H5)4]X-H2O system under hydrothermal conditions without seed crystals was studied. It was shown that the test anions can be arranged in the following series in terms of the preferential formation of zeolite beta: F−, SO 4 2− , PO 4 3− , (CH2COO) 2 2− > HCOO− > (COO) 2 2− , CH3COO− ≫ Cl− ∼ NO 3 − ≫ Br− ≫ I− ≫ ClO 4 − . In particular, the fluoride and the anions of polybasic acids facilitate the formation of zeolite, whereas perchlorate, bromide, and iodide ions inhibit its formation. The experiments showed that anions facilitating the formation of zeolite beta make it possible to synthesize zeolite within the same broad range of chemical composition of the reaction mixture as in the case of [N(C2H5)4]OH. The reveled classification of anions into groups coincides with their categorization by Samoilov into anions with positive and negative hydration.