Mesoporous silica supported Rh catalysts for high concentration N2O decomposition
Mesoporous silica supported Rh catalysts for high concentration N2O decomposition
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DOI：
10.1016/j.apcatb.2014.10.008
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发表时间：
2015-04
影响因子：
22.1
通讯作者：
M. Piumetti;M. Hussain;D. Fino;N. Russo
中科院分区：
文献类型：
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作者：
M. Piumetti;M. Hussain;D. Fino;N. Russo
通过湿法浸渍介孔二氧化硅制备了一套含 Rh 催化剂（Rh-MCM-41、Rh-SBA-15、Rh-KIT-6 和 Rh-MCF，标称 Rh 含量 = 1 wt.%），并进行了高浓度 N2O 减排测试。通过补充技术对材料的物理化学性质进行了研究。由于 MCF 二氧化硅具有更好的结构性质，Rh-MCF 催化剂在 N2O 分解方面取得了最佳性能。事实上，MCF 型载体表现出具有超大孔（高达 40 nm）的三维介孔性，这使得小 RhOx 颗粒（约 1 nm）均匀分布在 MCF 的高（内部）表面积上。此外，N2O分子也很容易接近Rh活性位点。最有前途的催化剂表现出最高含量的Rh1+物种、最容易的铑还原性和最丰富的Rh表面位点。这些重要特征反映了不同的Rh颗粒尺寸并在催化活性中发挥作用。在1-2.5 nm尺寸范围内观察到催化活性与RhOx颗粒尺寸之间的显着关系，从而证实了N2O分解在RhOx纳米颗粒上的分散敏感性。
A set of Rh-containing catalysts (Rh-MCM-41, Rh-SBA-15, Rh-KIT-6 and Rh-MCF, nominal Rh content = 1 wt.%) has been prepared by wet impregnation of mesoporous silicas and tested for high concentration N2O abatement. The physico-chemical properties of the materials have been investigated by means of complementary techniques.The best performances, in terms of N2O decomposition, have been achieved for the Rh-MCF catalyst, due to the better textural properties of the MCF silica. In fact, the MCF-type support exhibits three-dimensional mesoporosity with ultra-large cells (up to 40 nm), which allow a uniform distribution of small RhOxparticles (≈1 nm) over the high (internal) surface area of the MCF. Moreover, the Rh active sites are also readily accessible to N2O molecules.The most promising catalyst has shown the highest amount of Rh1+species, the easiest rhodium reducibility and the greatest abundance of Rh surface sites. These important features reflect the different Rh particle sizes and play a role in catalytic activity.A remarkable relationship between the catalytic activity and the dimension of the RhOxparticles has been observed in the 1–2.5 nm size domain, thus confirming the dispersion-sensitivity of N2O decomposition over RhOxnanoparticles.