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The main disadvantage of microporous SSZ-13 catalyst used in the methanol to olefins(MTO) process is its rapid deactivation due to its relatively low coke resistance. Meanwhile, the hierarchical zeolites usually exhibit improved catalytic stability thanks to their better mass transfer ability. Herein, the hierarchically nanoporous SSZ-13 zeolites were one-pot synthesized by using N,N,N-trimethyl-1-adamantanammonium hydroxide as a microporous structure directing agent and C_(18)H_(37) N~+(CH_3)_2 C_6H_(12) N~+(CH_3)_2 C_6 H_(13)(Br~-)_2(hereinafter abbreviated as C_(18-6-6) Br_2) as a mesoporogen. The hierarchically nanoporous SSZ-13 catalyst was characterized by XRD, N_2 physisorption, SEM, TEM, TG-DTG, ~(27) Al and ~(29) SiNMR spectroscopy and NH_3-TPD techniques. The results showed that the hierarchical SSZ-13 zeolite synthesized in the presence of the C_(18-6-6) Br_2 surfactant exhibits aggregates of primary nanocrystals and contains the well-developed mesopores and excellent acidity. Compared to its conventional counterpart, the hierarchical SSZ-13 zeolite has longer catalytic lifetime and higher selectivity for ethylene and propylene in the MTO reaction, which can be attributed to the synergistic effect of their good acidity and improved diffusion properties resulted from the hierarchical pore structure.
The main disadvantage of microporous SSZ-13 catalyst used in the methanol to olefins (MTO) process is its rapid deactivation due to to their better low pressure transfer ability. Herein , the hierarchically nanoporous SSZ-13 zeolites were one-pot synthesized by using N, N, N-trimethyl-1-adamantanammonium hydroxide as a microporous structure directing agent and C 18 H 37 N ~ + CH 3 _2 C_6H_ (12) N ~ + (CH_3) _2 C_6 H_ (13) (abbreviated as C_ (18-6-6) Br_2) as a mesoporogen. The hierarchically nanoporous SSZ-13 catalyst was characterized by XRD , N_2physisorption, SEM, TEM, TG-DTG, ~ (27) Al and ~ (29) SiNMR spectroscopy and NH_3-TPD techniques. The results showed that the hierarchical SSZ-13 zeolite synthesized in the presence of the C_ (18- 6-6) Br_2 surfactant exhibits aggregates of primary nanocrystals and contains the well-developed mesopores and excellent acidit y. Compared to its conventional counterpart, the hierarchical SSZ-13 zeolite has longer catalytic lifetime and higher selectivity for ethylene and propylene in the MTO reaction, which can be attributed to the synergistic effect of their good acidity and improved diffusion properties resulted from the hierarchical pore structure.