Enhanced stability and propylene yield in methanol to light olefins conversion over nanostructured SAPO‐34/ZSM‐5 composite with various SAPO‐loadings

Abstract

Abstract Nanostructured core‐shell silicoaluminophosphate (SAPO)‐34/zeolite socony mobil (ZSM)‐5 composite has been synthesized with various SAPO‐34 loadings in order to control light olefins selectivity and increase its lifetime in methanol to olefins process. Physicochemical properties and catalytic performance of SAPO‐34/ZSM‐5 composite catalyst were different, compared with the parent SAPO‐34 and ZSM‐5. As‐synthesized samples were characterized by different methods such as X‐Ray diffraction, field emission scanning electron microscopy, Brunauer–Emmett–Teller, energy‐dispersive X‐ray, Fourier transform infrared spectroscopy, and NH 3 ‐temperature‐programmed desorption techniques. By increasing SAPO‐34 content in composite catalysts, relative crystallinity of CHA‐phase (chabazite) was enhanced, whereas it was decreased for MFI‐phase. Also, surface area improved by increasing SAPO‐34 loading in core‐shell composite catalysts. The results of the activity test showed that lifetime remarkably increased by using composite catalysts. Compared with the parent SAPO‐34 and ZSM‐5, the composite catalyst with 80% SAPO‐34 loading showed higher methanol conversion and olefins selectivity with time on stream. This is due to the synergic effect between SAPO‐34 and ZSM‐5 zeolites in composite catalyst.