Size-Controlled Synthesis of Metallosilicates with MTW Structure and Catalytic Performance for Methanol-to-Propylene Reaction

作者：Taniguchi Taichi; Nakasaka Yuta^*; Yoneta Keitaro; Tago Teruoki; Masuda Takao

来源：Catalysis Letters, 2016, 146(3): 666-676.

DOI：10.1007/s10562-015-1683-4

• Size-controlled synthesis
• Metallosilicate
• MTW zeolite
• Methanol to propylene reaction

The synthesis of metallosilicates with a MTW structure was achieved using tetraethylammonium bromide (TEABr) and methyltriethylammonium chloride (MTEACl) as organic structure-directing agents (OSDAs). MTW zeolites (Al-MTW, Si-MTW, Fe-MTW and (Al, Fe)-MTW) were obtained by hydrothermal synthesis. The crystal size of the resulting MTW zeolite strongly depended on the type of OSDA, in which the column-like and agglomerated nano-sized crystals could be produced by using MTEACl and TEABr, respectively as an OSDA. Isomorphous substitution of Fe for Si was demonstrated by UV-vis spectra and ac-NH3-TPD profiles. These analyses indicated that Fe atoms were incorporated into the lattice framework and that almost all of the Fe species were well-dispersed without forming bulky iron oxide particles. The ac-NH3-TPD profiles showed that the acid strength of the Fe-MTW zeolite was weaker than that of the Al-MTW zeolite. Al-MTW zeolites with different crystal sizes were applied to methanol-to-propylene reactions. The nanosized Al-MTW zeolite exhibited a longer catalyst life time compared to the macro-sized Al-MTW zeolite. Since decreasing the acid strength of the MTW zeolite inhibited excessive reactions followed by the formation of aromatics, the (Al, Fe)-MTW zeolite exhibited higher yields of propylene and butenes and a lower yield of aromatics compared with the Al-MTW zeolite.

• 出版日期2016-3