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Can Support Acidity Predict Sub-Nanometer Catalyst Activity Trends?
ACS Catalysis ( IF 11.3 ) Pub Date : 2017-09-06 00:00:00 , DOI: 10.1021/acscatal.7b01844
Andrew S. Crampton 1 , Marian D. Rötzer 1 , Uzi Landman 2 , Ueli Heiz 1
Affiliation  

The effect of metal-oxide support on the activity of ethylene hydrogenation catalyzed by size-selected platinum clusters (8–20 atoms per cluster) is investigated. Size-selected clusters have been shown to possess unique catalytic properties which change as a function of the precise cluster size. The temperature-programmed reaction and isothermal pulsed molecular beam data both demonstrate a size-dependent reactivity on each support. However, predicted trends based on the acidic (SiO2) or basic (MgO) properties of the support are more subtle, with the influence of the support also being a function of the cluster size. Only the average hydrogenation activity of all sizes measured, as well as the CO stretching frequency on clean clusters, were observed to follow predicted trends, but atomic-level resolution demonstrates a much more complicated picture. Pt13 had the lowest hydrogenation activity of all sizes on amorphous SiO2, while being the most active size on MgO, and trends between the same cluster sizes were observed to exhibit opposing behavior between the two supports. This demonstrates the potential of cluster materials for designing catalytic systems and also the difficulties encountered when formulating general concepts for reactivity in the nonscalable size regime.

中文翻译:

可以支持酸度预测亚纳米级催化剂的活性趋势吗?

研究了金属氧化物载体对尺寸选择的铂簇(每簇8-20个原子)催化的乙烯加氢活性的影响。已显示尺寸选择的簇具有独特的催化性能,其随精确簇尺寸的变化而变化。程序升温反应和等温脉冲分子束数据均证明了每种载体的反应性均取决于其大小。但是,基于酸性(SiO 2)或支撑的基本(MgO)特性更加微妙,支撑的影响也是簇大小的函数。仅观察到所有尺寸的平均氢化活性以及在干净簇上的CO拉伸频率都遵循预测的趋势,但是原子级分离度却显示出更为复杂的图景。在无定形SiO 2上,Pt 13的氢化活性最低。,虽然是MgO上最活跃的尺寸,但观察到相同簇尺寸之间的趋势在两个支撑物之间表现出相反的行为。这证明了簇状材料在设计催化体系中的潜力,以及在制定不可缩放尺寸体系中反应性的一般概念时遇到的困难。
更新日期:2017-09-07
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