Аннотация:This study investigates the effects of FAU(Y) crystal size (350, 450, and 850 nm) on the physicochemical properties and catalytic performance of CsNaY samples in the alkylation of aniline with methanol. The physicochemical properties of the samples were examined by SEM, X-ray fluorescence analysis, low-temperature nitrogen adsorption, XRD, NH3–TPD, IR spectroscopy of adsorbed chloroform, and 27Al MAS NMR. Reducing the zeolite crystal size was found to strengthen the CsNaY basic properties and enhance the selectivity towards N-alkylated products. The highest activity and stability in aniline methylation was achieved by the CsNaY sample consisting of 450-nm crystals that had a Na+ for Cs+ ion exchange degree of 64% and was modified with CsOH. This sample provided aniline conversion of 95% and the selectivity towards N-alkylated product of 99.8%.