Characterization of the Surface Acidity of MFI Zeolite Nanosheets by 31P NMR of Adsorbed Phosphine Oxides and Catalytic Cracking of Decalin

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• 作者：Yongbeom Seo ; Kanghee Cho ; Younjae Jung ; Ryong Ryoo
• 刊名：ACS Catalysis
• 出版年：2013
• 出版时间：April 5, 2013
• 年：2013
• 卷：3
• 期：4
• 页码：713-720
• 全文大小：416K
• 年卷期：v.3,no.4(April 5, 2013)
• ISSN：2155-5435

文摘

MFI zeolite nanosheets tailored to 2.5-nm thickness were synthesized using a surfactant-type zeolite structure-directing agent, [C₂₂H₄₅鈥揘⁺(CH₃)₂鈥揅₆H₁₂鈥揘⁺(CH₃)₂鈥揅₆H₁₃](Br鈥?/sup>)₂. The zeolite nanosheets possessed Br酶nsted acid sites on their external surfaces as well as in the internal micropore walls. The acid strength and concentration was characterized by the ³¹P NMR signals of the adsorbed trimethylphosphine oxide and tributylphosphine oxide. The ³¹P NMR investigation identified three types of Br酶nsted acid sites with different strengths on external surfaces; there were four types inside the micropores. A linear correlation has been established between the number of the external strongest acid sites and the catalytic activity in decalin cracking for the MFI zeolite catalysts investigated in this work.

Keywords:

acidity; zeolite nanosheets; NMR; phosphine oxide; cracking; decalin