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首页> 外文期刊>Physical chemistry chemical physics: PCCP >Microscopic models of PdZn alloy catalysts: structure and reactivity in methanol decomposition
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Microscopic models of PdZn alloy catalysts: structure and reactivity in methanol decomposition

机译：PdZn合金催化剂的微观模型：甲醇分解的结构和反应性

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摘要

We review systematic experimental and theoretical efforts that explored formation, structure and reactivity of PdZn catalysts for methanol steam reforming, a material recently proposed to be superior to the industrially used Cu based catalysts. Experimentally, ordered surface alloys with a Pd : Zn ratio of similar to 1 : 1 were prepared by deposition of thin Zn layers on a Pd( 111) surface and characterized by photoelectron spectroscopy and low-energy electron diffraction. The valence band spectrum of the PdZn alloy resembles closely the spectrum of Cu( 111), in good agreement with the calculated density of states for a PdZn alloy of 1 : 1 stoichiometry. Among the issues studied with the help of density functional calculations are surface structure and stability of PdZn alloys and effects of Zn segregation in them, and the nature of the most likely water-related surface species present under the conditions of methanol steam reforming. Furthermore, a series of elementary reactions starting with the decomposition of methoxide, CH3O, along both C - H and C - O bond scission channels, on various surfaces of the 1 : 1 PdZn alloy [ planar ( 111), ( 100) and stepped ( 221)] were quantified in detail thermodynamically and kinetically in comparison with the corresponding reactions on the surfaces Pd( 111) and Cu( 111). The overall surface reactivity of PdZn alloy was found to be similar to that of metallic Cu. Reactive methanol adsorption was also investigated by in situ X-ray photoelectron spectroscopy for pressures between 3 x 10(-8) and 0.3 mbar.
机译：我们回顾了系统的实验和理论研究，探索了甲醇蒸汽重整用PdZn催化剂的形成，结构和反应性，该材料最近被提出优于工业上使用的Cu基催化剂。实验上，通过在Pd（111）表面上沉积薄的Zn层来制备Pd：Zn比接近1：1的有序表面合金，并通过光电子能谱和低能电子衍射对其进行表征。 PdZn合金的价带光谱与Cu（111）的光谱非常相似，与化学计量比为1：1的PdZn合金的态密度计算值非常吻合。借助密度泛函计算研究的问题包括PdZn合金的表面结构和稳定性以及其中Zn偏析的影响，以及在甲醇蒸汽重整条件下最可能与水有关的表面物种的性质。此外，在1：1 PdZn合金的各种表面上，沿着CH和OH断裂通道的甲醇氧化物CH 3 O分解开始发生一系列基本反应[平面（111），（100）并呈阶梯状）。 （221）]与表面Pd（111）和Cu（111）上的相应反应相比，在热力学和动力学上进行了详细定量。发现PdZn合金的整体表面反应性与金属Cu相似。还通过原位X射线光电子能谱研究了在3 x 10（-8）和0.3 mbar之间的压力下反应性甲醇的吸附。

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