CO poisoning of ethylene hydrogenation over Pt catalysts: a comparison of Pt(111) single crystal and Pt nanoparticle activities
CO poisoning of ethylene hydrogenation over Pt catalysts: a comparison of Pt(111) single crystal and Pt nanoparticle activities
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DOI：
10.1023/a:1022628404888
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发表时间：
2003-03-01
影响因子：
2.8
通讯作者：
Somorjai, GA
中科院分区：
文献类型：
--
作者：
Grunes, J;Zhu, J;Somorjai, GA
在两种铂系催化剂上研究了一氧化碳存在下乙烯加氢反应的中毒效应。催化剂是Pt（111）单晶和沉积在氧化铝上的光刻制造的铂纳米颗粒。Pt（111）的气相色谱结果表明，在413 K时，CO的吸附使Pt（111）表面的转换速率从10（1）分子/Pt位/s降低到10（2）分子/Pt位/s，中毒表面的氢化活化能变为20.2 ± 0.1 kcal/mol。Pt（111）催化剂上乙烯加氢反应的活化能为10.8kcal/mol。当CO吸附在Pt纳米颗粒阵列上时，反应速率从10（2）nmol/s降低到10（0）nmol/s。然而，活化能基本保持不变。Pt纳米颗粒在不存在CO的情况下显示出乙烯氢化的表观活化能为10.2 +/- 0.2 kcal/mol，在CO中毒的纳米颗粒阵列上显示出11.4 +/- 0.6 kcal/mol。这是首次观察到Pt（111）和Pt纳米颗粒阵列之间的催化行为的显著差异。据建议，在氧化物金属界面的活性位负责的两个模型铂催化剂上的加氢反应的活化能的差异。
The ethylene hydrogenation reaction was studied on two platinum model catalyst systems in the presence of carbon monoxide to examine poisoning effects. The catalysts were a Pt(111) single crystal and lithographically fabricated platinum nanoparticles deposited on alumina. Gas chromatographic results for Pt(111) show that CO adsorption reduces the turnover rate from 10(1) to 10(2) molecules/Pt site/s at 413 K, and the activation energy for hydrogenation on the poisoned surface becomes 20.2 +/- 0.1 kcal/mol. The activation energy for ethylene hydrogenation over Pt(111) in the absence of CO is 10.8 kcal/mol. The Pt nanoparticle system shows the same rate for the reaction as over Pt(111) in the absence of CO. When CO is adsorbed on the Pt nanoparticle array, the rate of the reaction is reduced from 10(2) to 10(0) nmol/s at 413 K. However, the activation energy remains largely unchanged. The Pt nanoparticles show an apparent activation energy for ethylene hydrogenation of 10.2 +/- 0.2 kcal/mol in the absence of CO and 11.4 +/- 0.6 kcal/mol on the CO-poisoned nanoparticle array. This is the first observation of a significant difference in catalytic behavior between Pt(111) and the Pt nanoparticle arrays. It is proposed that the active sites at the oxide metal interface are responsible for the difference in activation energies for the hydrogenation reaction over the two model platinum catalysts.