Comparative Study of Diverse Copper Zeolites for the Conversion of Methane into Methanol
Comparative Study of Diverse Copper Zeolites for the Conversion of Methane into Methanol
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DOI：
10.1002/cctc.201700768
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发表时间：
2017-10-10
期刊：
影响因子：
4.5
通讯作者：
van Bokhoven, Jeroen A.
中科院分区：
文献类型：
--
作者：
Park, Min Bum;Ahn, Sang Hyun;van Bokhoven, Jeroen A.
比较了12种铜分子筛（莫尔、EON、MAZ、MEI、BPH、FAU、LTL、MFI、HEU、FER、SZR和CHA）在甲烷分步部分氧化制甲醇反应中的表征和反应性能。Cu 2+离子交换的沸石Ω，一种MAZ型材料，显示出最高的产率（86 μ mol g（cat.）(-1))在这些材料中，经过高温活化和液体甲醇萃取。高产率归因于相对高密度的铜-氧代活性物质，其形成于其三维8元（MB）环通道中。原位UV/维斯研究表明，不同的分子筛在高温活化后形成不同的铜物种，表明不存在普遍的活性物种。尽管如此，存在实现高甲醇产率所需的一些主要因素：1）高度分散的铜-氧代物质; 2）在小孔沸石中大量交换的铜; 3）适度高的活化温度;和4）使用质子形式的沸石前体。以质子形式的丝光沸石为前体的Cu-ω和Cu-丝光沸石在氧气中活化并在仅200摄氏度即等温条件下与甲烷反应后产生甲醇。
The characterization and reactive properties of copper zeolites with twelve framework topologies (MOR, EON, MAZ, MEI, BPH, FAU, LTL, MFI, HEU, FER, SZR, and CHA) are compared in the stepwise partial oxidation of methane into methanol. Cu2+ ion-exchanged zeolite omega, a MAZ-type material, reveals the highest yield (86 mu mol g(cat.)(-1)) among these materials after high-temperature activation and liquid methanol extraction. The high yield is ascribed to the relatively high density of copper-oxo active species, which form in its three-dimensional 8-membered (MB) ring channels. In situ UV/Vis studies show that diverse copper species form in different zeolites after high-temperature activation, suggesting that there are no universally active species. Nonetheless, there are some dominant factors required for achieving high methanol yields: 1) highly dispersed copper-oxo species; 2) large amount of exchanged copper in small-pore zeolites; 3) moderately high temperature of activation; and 4) use of proton form zeolite precursors. Cu-omega and Cu-mordenite, with the proton form of mordenite as the precursor, yield methanol after activation in oxygen and reaction with methane at only 200 degrees C, that is, under isothermal conditions.