Synthesis of hierarchical SAPO-34 aggregates composed of ultrasmall nanocrystals and their stable catalytic performance for 1-butene cracking

Abstract

The nanosized and hierarchical SAPO-34 zeolite has attracted much more attention due to its excellent catalytic performance and high stability. Poly(diallyldimethylammonium chloride) (PDDA) was introduced into initial gels to synthesize hierarchical SAPO-34 aggregates composed of 20–30 nm nanocrystals. The effect of Si/Al ratio, H₂O/Al ratio and PDDA content on SAPO-34 was systematically investigated by X-ray diffraction, scanning and transmission electron microscopy, N₂ adsorption-desorption and NH₃-TPD. The addition of PDDA further reduced crystal size and increased mesoporosity of hierarchical SAPO-34 aggregates, which exhibited better and more stable catalytic performance for 1-butene conversion rate and propylene selectivity in 1-butene cracking reaction.