Effects of Ion Exchange Degree on the Physicochemical and Catalytic Properties of CsNaY

This study investigates the effects of the degree of ion exchange of sodium cations for cesium cations in FAU(Y) on its physicochemical properties. Using aqueous and solid-state ion exchange, a number of NaY samples with an exchange degree of sodium cations for cesium cations varying from 29 to 89% were prepared. The samples were examined by SEM, X-ray fluorescence, low-temperature nitrogen adsorption, XRD, NH 3 -TPD, IR spectroscopy of adsorbed chloroform, and 27 Al MAS NMR. It was demonstrated that samples with exchange degrees up to 87% can be synthesized with their crystalline structure intact. The test of the catalytic properties of the synthesized samples in aniline alkylation with methanol showed a growth in the selectivity for N-alkylated products as the number and strength of basic sites were progressively increased. Impregnating the Cs-containing zeolites with CsOH was found to significantly enhance the operating stability of the samples and the yield of N-alkylated products, compared to CsNaY. The CsOH-modified catalysts with a Na + /Cs + exchange degree of 54–77% proved to be the most active and stable in aniline alkylation with methanol: they provided aniline conversion of 81–88% and selectivity for N-alkylation products as high as 99.6–99.7 mol %.