Green and facile synthesis of binder-free shaped EU-1 zeolite and its application in n-hexane cracking

The traditional hydrothermal synthesis of EU-1 zeolite is accompanied by the production of a substantial amount of mother liquor waste due to the ultrahigh water-to-silica ratio used, and requires binders during the subsequent shaping process, leading to diffusion limitation. Herein, the binder-free shaped EU-1 zeolite was prepared by a steam-assisted method, dramatically reducing the amount of mother liquor waste. In comparison with the traditional synthesis process, only 1/20 of the amount of water is used. The formation process of the binder-free shaped EU-1 zeolites was monitored with XRD, FTIR and SEM. The zeolites with different SiO₂/Al₂O₃ ratios (SARs, SAR = 30 ~ 150) were prepared, characterized and exhibited excellent catalytic properties for the n-hexane to olefin (HTO) reaction. The results show that as the SAR increases, the crystallinity improves, enhancing the mesoporous properties and propylene selectivity of the binder-free shaped EU-1 zeolite, and achieving a maximum propylene yield of 45.1% at an SAR of approximately 150 by the HTO process. Compared with the traditional conventional hydrothermal synthesis EU-1 catalyst, the conversion and propylene yield increase by 33.1 and 23.5%, respectively. This synthesis strategy provides an effective approach for the green synthesis of EU-1 zeolite with excellent performance in the HTO.