Improvement of catalytic properties of SAPO-11 molecular sieves synthesized in H2O–CTAB–butanol system

SAPO-11 molecular sieves have been synthesized in both the conventional synthesis system and the H2O–cetyltrimethylammomium bromide (CTAB)–butanol system by the hydrothermal synthesis method. Characterization of these samples by X-ray diffraction (XRD), infrared spectroscopy (IR) of the adsorbed pyridine, 29Si solid-state magic-angle spinning (MAS), nuclear magnetic resonance (NMR), and catalytic test reaction reveals that SAPO-11 synthesized in H2O–CTAB–butanol system has small crystal sizes and larger amounts of Brönsted acid sites. Such sites not only give rise to an increase of n-dodecane conversion, isomer yield and selectivity, but also increase the monobranched isomer selectivity.