Mengwen Huang, Yasumura Shinsaku, Toyao Takashi, Shimizu Ken-Ichi, Maeno Zen
Institute for Catalysis, Hokkaido University, N-21, W-10, Sapporo 001-0021, Japan.
School of Advanced Engineering, Kogakuin University, 2665-1, Nakano-cho, Hachioji, 192-0015, Japan.
Phys Chem Chem Phys. 2023 Apr 12;25(15):10211-10230. doi: 10.1039/d3cp00478c.
Metal-exchanged zeolites have great potential to form unique active metal species and develop their catalysis by promoting small molecules such as light alkanes. Ga-exchanged zeolites have attracted attention as promising heterogeneous catalysts for dehydrogenative light-alkane transformations. The speciation of active Ga species in reduced and oxidized Ga-exchanged zeolites and their reaction mechanisms have been discussed in several studies based on experimental and theoretical investigations. In contrast, studies on In-exchanged zeolites have been far less explored, and thus active In-species have rarely been investigated. In this perspective, we summarized our investigations on In- and Ga-exchanged zeolites for light-alkane transformations. Our research group reported the formation of In-oxo clusters using the O treatment of In-CHA and their potential for the partial oxidation of CH (POM) at room temperature. We also observed the formation of In-hydrides in CHA zeolites during the preparation through reductive solid-state ion-exchange (RSSIE) and revealed their catalysis for non-oxidative CH dehydrogenation (EDH). Their detailed structures and reaction mechanisms are discussed in combination with spectroscopic, kinetic, and theoretical studies. Furthermore, comparative studies on the formation of Ga-oxo clusters for POM at room temperature and the controlled formation of Ga-hydrides for selective EDH were conducted. The obtained results and insights are comprehensively discussed, including the relationship between the local structure of the active In/Ga species and reaction selectivity, as well as the influence of different zeolite frameworks on the formation of active species.
金属交换沸石在形成独特活性金属物种以及通过促进小分子（如轻质烷烃）来发展其催化作用方面具有巨大潜力。镓交换沸石作为用于脱氢轻质烷烃转化的有前景的多相催化剂已受到关注。基于实验和理论研究的多项研究讨论了还原态和氧化态镓交换沸石中活性镓物种的形态及其反应机理。相比之下，对铟交换沸石的研究则少得多，因此活性铟物种很少被研究。从这个角度出发，我们总结了我们对铟和镓交换沸石用于轻质烷烃转化的研究。我们的研究小组报道了通过对铟-CHA进行氧处理形成铟-氧簇及其在室温下对甲烷部分氧化（POM）的潜力。我们还观察到在通过还原固态离子交换（RSSIE）制备过程中CHA沸石中铟氢化物的形成，并揭示了它们对非氧化甲烷脱氢（EDH）的催化作用。结合光谱、动力学和理论研究讨论了它们的详细结构和反应机理。此外，还对室温下用于POM的镓-氧簇的形成以及用于选择性EDH的镓氢化物的可控形成进行了比较研究。对获得的结果和见解进行了全面讨论，包括活性铟/镓物种的局部结构与反应选择性之间的关系，以及不同沸石骨架对活性物种形成的影响。
