Methylcyclopentenyl cation mediated reaction route in methanol-to-olefins reaction over H-RUB-50 with small cavity

• 来源期刊: 能源化学
• 年，卷（期）: 2020,（6）
• 页码范围: 25-30
• 页数: 6页
• 语种: 英文

摘要

Methylcyclopentenyl cations (MCP+) have been regarded as active intermediates during methanol conversion,however,their function mode in the reaction are still uncertain.In our recent report,trimethylcyclopentenyl cation (triMCP+) and its deprotonated counterpart (trimethylcyclopentadiene,triMCP) were directly captured on H-RUB-50 catalyst with small cavity by the aid of in situ 13C MAS NMR spectroscopy,and their higher catalytic reactivity were clarified by 12C/13C-CH3OH isotopic switch experiment.In this contribution,an alternative route-cyclopentadienes-based cycle was applied on methanol conversion catalyzed on the H-RUB-50,in which ethene was produced with the participation of triMCP+ as critical intermediate.Then the cyclopentadienes-based cycle was predicted to be energetically favorable for ethene formation by density functional theory (DFT) calculations.The energetic comparison of paring mechanism in the aromatics-based cycle and cyclopentadienes-based cycle with the involvements of trimethylcyclopentadienyl (triMCPdi+) and triMCP+ as the corresponding active intermediates suggests that cyciopentadienes-based cycle is a feasible route for ethene formation.Furthermore,this work highlights the importance of the steric constraint and the host-guest interaction induced by the zeolite with cavity structure in the formation of intermediates and reaction pathway.