Synthesis of composite zeolites composed of SAPO-5 and SAPO-34 and its application in methanol dehydration to light olefins

Abstract

In present work, bi-phases composite zeolites consisting of SAPO-5 and SAPO-34 (named as SSC) are prepared by a traditional hydrothermal way, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption–desorption, intelligent gravimetric analyzer (IGA), intrusive mercury technology, and NH3-TPD techniques. The results display that the crystals in the as-synthesized composites have a hierarchical pore system with a size of about 3–130 nm, which displays a butterfly-like pattern on the crystal faces and runs throughout the whole crystal. Catalytic performances of the as-synthesized SSC catalysts are tested during methanol to olefin (MTO). As compared with a microporous composite catalyst, the hierarchical SSC composite catalyst displays excellent catalytic performances with a prolonged catalytic life and an elevated selectivity for light olefins.