Catalytic properties of silver-exchanged zeolites for propene production by conversion of methane in the presence of ethene

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• 作者：Toshihide Baba ; Yasuyoshi Iwase ; Koji Inazu ; Dilshad Masih ; Akihiko Matsumoto
• 关键词：CH₄ conversion ; Propene synthesis ; Ag⁺-exchanged zeolites ; Silver hydride ; ¹H MAS NMR
• 刊名：Microporous and Mesoporous Materials
• 出版年：2007
• 出版时间：19 April 2007
• 年：2007
• 卷：101
• 期：1-2
• 页码：142-147
• 全文大小：170 K

文摘

Conversion of ¹³C-labeled methane (¹³CH₄) in the presence of ethene (C₂H₄) over Ag⁺-exchanged zeolites (Ag–A, Ag–Y and Ag-ZSM-5) at 673 K affords a mixture of ¹³C-labeled propene (¹³CC₂H₆) and unlabeled propene (C₃H₆) at a ratio of approximately 80/20. The same reaction over Ag₃PW₁₂O₄₀ and proton-exchanged zeolites (H-ZSM-5 and H–Y) yields only unlabeled propene. The role of silver species in the activation of methane in this system is examined by proton nuclear magnetic resonance analysis, and it is revealed that silver cationic clusters (Ag_n⁺ in Ag⁺-exchanged zeolites are responsible for the activation of methane to form silver hydride species (Ag_n–H) and highly polarized , which reacts with ethene to form propene and acidic protons. Regeneration of Ag_n⁺ proceeds by reaction of acidic protons with Ag_n–H accompanied by the formation of H₂. Silver cations in Ag₃PW₁₂O₄₀, a silver salt, do not dissociate the C–H bond of CH₄ and thus cannot catalyze the reaction of methane and ethene.