Au/MgO and Au/Mg(OH)₂ catalysts were prepared and used as model systems to study the participation of the Au–support interface in the water-gas shift reaction (WGS). Au/MgO and Au/Mg(OH)₂ showed similar WGS kinetics, consistent with a similar WGS reaction mechanism. However, Au/MgO had a lower apparent reaction order with respect to H₂O and was identified as having a higher specific WGS rate compared with Au/Mg(OH)₂ at the same average Au particle size. The focus of the work is on Au/MgO, where we observed a correlation between the hydroxyl group coverage and WGS rate. The measured kinetic isotope effect, DFT calculations, and operando FTIR for that catalyst are all consistent with surface carboxyl formation as the rate-determining step. Comparisons of hydroxyl group coverage with and without Au suggest that the formation of OH groups is strongly influenced by the presence of Au and likely to be highest at the Au–MgO interface, as supported by theoretical calculations. Temperature programmed reaction shows that Au is necessary to catalyze reaction of the surface OH groups with CO. This work confirms the importance of the metal support interface in WGS catalysis and suggests that the unique chemistry at the interface offers both an explanation of catalyst behaviour and a new opportunity to design materials with improved function for additional catalytic applications.

中文翻译：

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界面羟基在Au / MgO催化剂上的水煤气变换反应中的参与

制备了Au / MgO和Au / Mg（OH）₂催化剂，并将其用作模型系统来研究Au-载体界面在水煤气变换反应（WGS）中的参与。Au / MgO和Au / Mg（OH）₂显示出相似的WGS动力学，与相似的WGS反应机理一致。然而，Au / MgO相对于H ₂ O具有较低的表观反应顺序，并且在相同的平均Au粒径下，与Au / Mg（OH）₂相比，具有更高的比WGS率。工作的重点是Au / MgO，我们观察到了羟基覆盖率和WGS速率之间的相关性。测得的动力学同位素效应，DFT计算和操作该催化剂的FTIR与速率确定步骤中的表面羧基的形成都一致。有和没有金的情况下羟基覆盖率的比较表明，羟基的形成受金的存在的强烈影响，并且在理论计算的支持下，可能在金-镁氧化物的界面处最高。程序升温反应表明Au是催化表面OH基团与CO反应的必要条件。这项工作证实了金属载体界面在WGS催化中的重要性，并暗示界面处独特的化学性质既可以解释催化剂的行为，又可以提供催化作用。设计功能改进的材料以用于其他催化应用的新机会。