One-Pot Hydrothermal Synthesis of a Dual-Metal-Modified CuMn-ZSM-5/SAPO-34 Zeolite with Excellent MTO Catalytic Performance

The composite molecular sieve catalysts with long reaction times were successfully synthesized by introducing Cu 2+ /Mn 2+ and ZSM-5 into the initial gel. The catalysts were characterized with XRD, SEM and NH 3 -TPD, and further investigated through the methanol-to-olefin reactions. The results showed that the addition of Cu 2+ caused the crystallinity of ZSM-5/SAPO-34 (Z-S) to increase significantly, but with addition of Mn 2+ , the crystallinity gradually decreased. With the increase of the Mn 2+ /Cu 2+ ratio, the desorption summits of the weak and strong acid sites gradually increased, but the weak acid centres gradually dominated, which is herein thought helped reducing formation of the coke. The designed Cu 0.05 -Mn 0.05 /Z-S samples showed beneficial catalytic performances with a lifetime of 1500 min, a 1.5-fold increase compared with the Cu 0.05 /Z-S, while their selectivities remained exceeding 89%. Graphical