Abstract: The NaY zeolite with small crystal size between 0.30 and 0.35 μm could be directly synthesized by the hydrothermal method, using sodium aluminate and silica sol as the main raw materials without seed gel or organic additives under hydrothermal conditions. The molar composition of reactants was 5.1 Na2O•Al2O3•10 SiO2•(140-220) H2O, and the reaction system was aged at room temperature for 3 d and was then crystallized at 100 ℃ for 9 h). The NaY zeolite samples were characterized by XRD, SEM, XRF, and DLS techniques. The samples have uniform granularity and good dispersibility. The catalytic performance of two La/Y catalyst samples with different crystal sizes for 1-butene pulse aromatization was measured. The La/Y catalyst sample with smaller crystal size has better aromatization stability, coke accommodation capability, and resistance ability to coke deposition.

Key words: direct synthesis, hydrothermal method, NaY zeolite, small crystal size, butene, aromatization