| 초록 |
By using a structure directing agent of tetra-n-butylphosphonium hydroxide , two type MFI catalysts (Si/Al: ∼30) with different mesoporosity were synthesized. The resulting ZSM-5 catalysts were formed via the interconnection of very thin lamellae; (1) high mesoporosity (H_30) and (2) low mesoporosity (L_30). From pyridine-based acid titration results, we could reveal that internal Brønsted acid sites of H_30 and C_75 (commercial ZSM-5 with Si/Al: ~75) were similar, but H_30 has a large amount of external Brønsted acid sites. The methanol to hydrocarbons (MTH) reaction performance demonstrates that H_30 preferred to produce propene over ethene compared to C_75, while L_30 showed a very poor MTH performance. Further, H_30 has very short diffusional length then C_75. Accordingly, H_30 allowed for achieving the ratio of propene to ethene as high as ∼9.1. And moreover, when ceria was doped at H_30, the stability for the MTH reaction and a propene to ethene ratio were improved much more. |
