Catalytic consequences of the identity of surface reactive intermediates during direct hydrogen peroxide formation on Pd particles
Catalytic consequences of the identity of surface reactive intermediates during direct hydrogen peroxide formation on Pd particles
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Pd 颗粒上直接形成过氧化氢过程中表面活性中间体特性的催化后果
DOI：
10.1016/j.jcat.2019.07.047
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发表时间：
2019-09
影响因子：
7.3
通讯作者：
Han Yi-Fan
中科院分区：
文献类型：
--
作者：
Tu Weifeng;Li Xinli;Wang Renquan;Malhi Haripal Singh;Ran Jingyu;Shi Yanling;Han Yi-Fan
H2 O2的形成直接从H2和O2的Pd颗粒在水中已被证明进行通过两个不同的动力学制度所定义的操作H2/O2比使用动力学，同位素实验和动力学控制条件下的颗粒尺寸的变化。这些动力学区域表现出不同的速率方程、动力学同位素效应和结构敏感性，而随着H2/O2比的增加，反应中间体从几乎未被化学吸附到被化学吸附氢（H*）饱和，这些区域之间发生了过渡。在几乎裸露的Pd表面上，不可逆的H2解离限制了H2 O2形成和H2转化的速率，因此，速率与H2压力成比例地增加，但与O2压力无关。在H* 饱和的Pd表面上，H2解离接近化学平衡，并且H* 介导的HOOH* 形成步骤成为唯一的动力学相关步骤，因此，速率变得对H2压力不敏感，但与O2压力成线性比例。H2 O2形成的一阶速率系数成为操作H2/O2比的单值函数。
H2O2 formation directly from H2 and O2 on Pd particles in water has proven to proceed via two different kinetic regimes defined by the operating H2/O2 ratios using kinetics, isotopic experiments and variation of particle sizes under conditions of kinetic control. These kinetic regimes exhibit different rate equations, kinetic isotope effects and structure sensitivity, while a transition among regimes occurs as the surface reactive intermediates changing from nearly uncovered to saturated with chemisorbed hydrogen (H*) with the increasing of H2/O2 ratio. On nearly bare Pd surfaces, irreversible H2 dissociation limits the rates of H2O2 formation and H2 conversion, thus, rates increase proportionally with H2 pressure but independent of O2 pressure. On H* saturated Pd surfaces, H2 dissociation approaches to chemical equilibrium and the H* mediated HOOH* formation step becomes the sole kinetically relevant step, therefore, rates become insensitive to H2 pressure but are linearly proportional to O2 pressure. The first-order rate coefficients for H2O2 formation become a single-valued function of the operating H2/O2 ratio.
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影响因子：
3.7
作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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