Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA.
Phys Chem Chem Phys. 2013 May 28;15(20):7768-76. doi: 10.1039/c3cp00126a. Epub 2013 Apr 19.
The effect of Zn on the CO adsorption and oxidation reaction is examined experimentally and theoretically on two PdZn catalysts with different compositions, namely the intermetallic 1:1 β-PdZn and α-PdZn as a solid solution of 9 at% Zn in Pd. These bimetallic catalysts, made using an aerosol derived method, are homogeneous in phase and composition so that the measured reactivity excludes support effects. Both specific reactivities for CO oxidation on these two PdZn catalysts were measured. It was found that the initial rates are high and different between these catalysts, presumably due to the weakening of the CO adsorption and easier binding of oxygen to Pd sites modified by Zn. However, the rates decrease with time and become comparable to that on Pd at the steady state. With the help of density functional theory, it was suggested that the transient kinetics are due to the oxidation of Zn during the catalysis, which yields pure Pd where the reaction takes place.
实验和理论研究考察了 Zn 对两种不同组成的 PdZn 催化剂上 CO 吸附和氧化反应的影响，这两种催化剂分别是具有 1:1 摩尔比的金属间化合物β-PdZn 和作为 Pd 中 9 at% Zn 固溶体的α-PdZn。这些使用气溶胶衍生方法制备的双金属催化剂在相和组成上是均匀的，因此测量的反应性排除了载体效应。对这两种 PdZn 催化剂上 CO 氧化的比活性进行了测量。结果发现，初始速率很高，并且在这两种催化剂之间存在差异，这可能是由于 CO 吸附的减弱以及 Zn 改性的 Pd 位上氧的结合更容易。然而，随着时间的推移，速率会下降，并在稳态下与 Pd 的速率相当。借助密度泛函理论，研究表明瞬态动力学是由于催化过程中 Zn 的氧化，这导致了反应发生的纯 Pd 的生成。
