Seeds Promoted Interzeolite Transformation of USY and Fumed Silica to Long-Lifetime SSZ-13 Catalysts in Methanol-to-Olefins Reaction via a Grinding Route

Abstract Two different seed crystals (K–CHA and nano-scaled SAPO-34) were used to promote the rapid interzeolite conversion of USY and fumed silica to pure SSZ-13 zeolite phase via a grinding route. The results show that both seeds can shorten the crystallization time of SSZ-13 zeolite to 24h, which is much shorter than the syntheses in the absence of seeds. The phase purity, morphology, textural parameters, elemental compositions and acid properties of two typical H–SSZ-13 samples with seeds were analyzed by XRD, SEM, N 2 physisorption, EDS and NH 3 –TPD techniques in detail, and compared with the sample without seeds and a reference sample. The results indicate that the introduction of seeds can effectively modify the acid properties of H–SSZ-13, especially their medium strong acid sites. The methanol-to-olefins (MTO) reaction was employed as a probe to evaluate the catalytic stability of above four H–SSZ-13 catalysts. The results reveal that the catalytic lifetime of the two catalysts using seeds is much longer than that of the one without seeds and the reference sample H–SSZ-13–RS. It was speculated that the appropriate concentration of medium strong acid sites may play a pivotal role in prolonging their catalytic lifetime. Here our findings may throw light on the rational design of long-lifetime H-SSZ-13 catalysts in the MTO reaction.