期刊
CHEMCATCHEM
卷 4, 期 9, 页码 1428-1435出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/cctc.201100503
关键词
Bronstead acid sites; heterogeneous catalysis; methanol-to-olefin; mesoporous materials; olefination
资金
- National Basic Research Program of China [2009CB623502]
- 111 project [B12015]
- Ministry of Education of the People's Republic of China [NCET-11-0251, IRT0927]
- Fonds der Chemischen Industrie
- Deutsche Forschungsgemeinschaft
The reasons for the high activity and long catalyst lifetime of AlPO-34 with a very low molar silicon content [nSi/(nAl+nP+nSi)=0.01] in the methanol-to-olefin (MTO) conversion were studied by using in situ FTIR spectroscopy, in situ UV/Vis spectroscopy, and solid-state NMR spectroscopy. The MTO activity of the low-silica AlPO-34 is explained by traces of accessible Bronsted acid sites existing in an isolated manner and characterized by a turnover frequency of 7.0 s-1 after a time-on-stream (TOS) of 1 h at 673 K. A contribution of Lewis acid sites to the MTO reaction over low-silica AlPO-34 could be excluded. The high selectivity of low-silica AlPO-34 to light olefins owes to a hydrocarbon pool consisting of benzene-type carbenium ions, as well as dienes. The very few Bronsted acid sites on low-silica AlPO-34 produce a much lower total coke content compared with SAPO-34, leading to an extended catalyst lifetime of the former material.
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