Catalytic Consequences of Chemisorbed Oxygen during Methanol Oxidative Dehydrogenation on Pd Clusters
Catalytic Consequences of Chemisorbed Oxygen during Methanol Oxidative Dehydrogenation on Pd Clusters
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DOI：
10.1021/acscatal.5b00068
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发表时间：
2015-05
期刊：
影响因子：
12.9
通讯作者：
Weifeng Tu;Y. Chin
中科院分区：
文献类型：
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作者：
Weifeng Tu;Y. Chin
表面氧含量和热力学活性的纳米Pd簇和它们的连接甲醇氧化脱氢的反应性建立从速率测量的动力学控制制度和氧吸收的研究在化学平衡。甲醇氧化脱氢的一级速率系数（转化率除以CH 3OH压力）是接触气相中氧气与甲醇比率的单值函数，因为该比率决定了氧气覆盖率、化学吸附氧气和未被占据的钯位点的相对丰度，进而决定了钯簇表面动力学相关步骤的身份。随着氧-甲醇比的增加，Pd簇上最丰富的表面中间体从未覆盖到化学吸附氧饱和;响应于覆盖率的这种变化，动力学相关步骤伴随着从氧解离到CH 3OH对氧吸附原子和氧空位的活化的变化。
Surface oxygen contents and thermodynamic activities of nanosized Pd clusters and their connection to the reactivities for methanol oxidative dehydrogenation are established from rate measurements in the kinetically controlled regime and oxygen uptake studies at chemical equilibrium. First-order rate coefficients for methanol oxidative dehydrogenation (turnover rates divided by CH3OH pressure) are single-valued functions of the oxygen-to-methanol ratio in the contacting gas phase because this ratio determines the oxygen coverages, the relative abundance of chemisorbed oxygen and unoccupied Pd sites, and in turn, the identities of the kinetically relevant steps at Pd cluster surfaces. As the oxygen-to-methanol ratio increases, the most abundant surface intermediates on Pd clusters vary from uncovered to saturated with chemisorbed oxygen; in response to this shift in coverages, the kinetically relevant step concomitantly varies from oxygen dissociation, to CH3OH activation on oxygen adatom and oxygen vacanc...