Isolated Platinum Atoms in Ni/γ-Al2O3 for Selective Hydrogenation of CO2 toward CH4
Isolated Platinum Atoms in Ni/γ-Al2O3 for Selective Hydrogenation of CO2 toward CH4
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DOI：
10.1021/acs.jpcc.9b03432
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发表时间：
2019-09-26
影响因子：
3.7
通讯作者：
Tanaka, Tsunehiro
中科院分区：
文献类型：
--
作者：
Kikkawa, Soichi;Teramura, Kentaro;Tanaka, Tsunehiro
介绍了一种由孤立的铂原子和镍原子组成的催化剂，该催化剂是以简单的浸渍法制备的氧化铝(Al_2O_3)为催化剂，经过典型的氢还原处理后得到的。与体镍原子(体镍)相比，该催化剂表现出相对较高的CH4生成速率，同时保持了良好的CH4析出选择性，尽管体铂原子(体铂)生成的是CO而不是CH4。动力学研究表明，镍-铂合金中异铂物种的两个作用之一是在低温下提供H-2解离中心，从而导致较高的CO2甲烷化活性。傅立叶变换红外光谱阐明了等铂物种的第二个作用；通过与周围的Ni原子合金化来调节d电子态，导致CO分子强烈地锚定在等铂原子上，这削弱了附着在铂原子上的CO物种的C-O键，并提高了周围Ni原子促进与氢进一步甲烷化的能力。
We introduce a catalyst composed of isolated Pt atoms surrounded by Ni atoms in a Ni-Pt alloy (iso-Pt), which was prepared on aluminum oxide (Al2O3) obtained by a simple impregnation method with typical hydrogen reduction pretreatment. This catalyst exhibited a relatively high CH4-formation rate while maintaining excellent selectivity for CH4 evolution, when compared to bulk Ni atoms (bulk-Ni), although bulk Pt atoms (bulk-Pt) produced CO rather than CH4. Kinetic studies revealed that one of the two roles of the iso-Pt species in the Ni-Pt alloy is to provide H-2 dissociation sites at low temperature, resulting in high CO2 methanation activity. Fourier transform infrared spectroscopy clarified the second role of the iso-Pt species; tuning of the d-electronic state by alloying to surrounding Ni atoms leads to CO molecules that are strongly anchored to the iso-Pt atoms, which weakens the C-O bond of the CO species attached to the Pt atoms and improves the abilities of the surrounding Ni atoms to promote further methanation with hydrogen.