Oxidative Reforming of Methane over Rh-Containing Zeolites: Active Species and Role of Zeolite Framework
Oxidative Reforming of Methane over Rh-Containing Zeolites: Active Species and Role of Zeolite Framework
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DOI：
10.1021/acs.iecr.1c01353
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发表时间：
2021-06
影响因子：
4.2
通讯作者：
Ryota Osuga;Shuhei Yasuda;M. Sawada;Ryo Manabe;H. Shima;Susumu Tsutsuminai;A. Fukuoka;Hirokazu Kobayashi;A. Muramatsu;T. Yokoi
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文献类型：
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作者：
Ryota Osuga;Shuhei Yasuda;M. Sawada;Ryo Manabe;H. Shima;Susumu Tsutsuminai;A. Fukuoka;Hirokazu Kobayashi;A. Muramatsu;T. Yokoi
采用离子交换法制备了Rh离子交换Y沸石（Rh-Y）和无定形二氧化硅-氧化铝（Rh-ASA）。 Rh 物种通过紫外可见光谱和红外光谱、TEM 和 H2-TPR 测量进行鉴定。孤立的Rh 阳离子优先在Y 沸石上形成，而Rh 氧化物主要存在于ASA 上。评估了制备的样品对甲烷氧化重整的催化活性。 Rh-ASA 上的 Rh 氧化物表现出比 Rh-Y 上分离的 Rh 阳离子略高的甲烷转化率和 CO 产率。另一方面，Rh-Y 上的催化寿命比 Rh-ASA 上的更长，因为孤立的 Rh 阳离子通过与沸石骨架的静电相互作用而免受聚集。此外，Rh-Y由于其高分散性，即使在低Rh含量下也表现出高催化活性。在实验事实的基础上，我们成功地澄清了甲烷氧化重整的活性Rh物种，并证明了沸石骨架对于稳定活性物种的有效性。本文为该催化体系中高活性催化剂的设计提供了重要的概念。
Rh ion-exchanged Y zeolite (Rh-Y) and amorphous silica–alumina (Rh-ASA) were prepared by the ion-exchange method. The Rh species were identified by UV–vis and IR spectroscopies, TEM, and H2-TPR measurements. Isolated Rh cations were preferentially formed on the Y zeolite, while Rh oxide mainly existed on ASA. The catalytic activities of the prepared samples for oxidative reforming of methane were evaluated. The Rh oxide on Rh-ASA exhibited slightly higher methane conversion and CO yield than those of the isolated Rh cation on Rh-Y. On the other hand, the catalytic lifetime over Rh-Y was longer than that over Rh-ASA because the isolated Rh cations were protected from aggregation by electrostatic interaction with the zeolite framework. In addition, Rh-Y exhibited a high catalytic activity even at low Rh contents owing to its high dispersibility. On the basis of the experimental facts, we have successfully clarified the active Rh species for this oxidative reforming of methane and demonstrated the effectiveness of the zeolite framework for the stabilization of the active species. This article provides the important concept for the design of highly active catalysts in this catalytic system.