Aiming at examining the effect of the coverage of modulated Au(Pd) atoms over bimetallic Pd-Au catalysts on the catalytic performance for direct oxidative esterification of methacrolein with methanol to methyl methacrylate. Here, two kinds of surface composition with different coverage of modulated Au(Pd) atoms on Au modulated Pd (AuPd) and Pd modulated Au (PdAu) catalysts have been designed and employed to investigate direct oxidative esterification using density functional theory calculation. The results showed that Pd modulated Au catalysts with higher coverage of modulated Pd atoms in the presence of pre-adsorbed O exhibited higher stability for resistance toward deactivation induced by H₂O deposition than Au modulated Pd and pure Au(Pd) catalysts. The formation of CH₃O species mainly came from pre-adsorbed O assisted CH₃OH activation rather than the direct breakage of CH₃OH via O-H bond, and it was more advantageous than the activation of CH₃OH via C-H bond with and without pre-adsorbed O. Additionally, Pd modulated Au catalysts with higher coverage of modulated Pd atoms improved the activity for MMA formation via MAL+*→CH₂C(CH₃)CO+(H)+CH₃O+*→MMA than Au modulated Pd and pure Au(Pd) catalysts. Moreover, the better catalytic performance (stability and activity) for direct oxidation esterification of Pd modulated Au catalysts with higher coverage of modulated Pd atoms were attributed to less average charge of surfaces atoms and the d-band center close to the Fermi level compared with pure Au(Pd) and Au modulated Pd catalysts. Therefore, it is proposed that Pd modulated Au catalysts are promising for direct oxidative esterification reaction of methacrolein with methanol to methyl methacrylate. This study not only helps understanding theory on direct oxidative esterification mechanism on bimetallic Pd-Au catalysts, but also provides clues for the design of high-effectively bimetallic Pd-Au catalysts for direct oxidative esterification.

旨在研究调制的 Au(Pd) 原子覆盖在双金属 Pd-Au 催化剂上对甲基丙烯醛与甲醇直接氧化酯化制备甲基丙烯酸甲酯的催化性能的影响。在这里，设计了两种在 Au 调制的 Pd (AuPd) 和 Pd 调制的 Au (PdAu) 催化剂上具有不同覆盖率的调制 Au(Pd) 原子的表面组成，并使用密度泛函理论计算研究直接氧化酯化。结果表明，与Au 调制 Pd 和纯 Au(Pd) 催化剂相比，在预吸附 O 存在下具有更高调制 Pd 原子覆盖率的 Pd 调制 Au 催化剂对 H ₂ O 沉积诱导的失活抗性表现出更高的稳定性。CH ₃的形成O类物质主要来自预吸附ö辅助CH ₃ OH活化，而不是CH直接破损₃ OH经由OH键，并且它比CH的激活更有利₃ OH经由CH键具有和不具有预吸附O.此外，Pd 调制的 Au 催化剂具有更高的调制 Pd 原子覆盖率，通过MAL+*→CH ₂ C(CH ₃ )CO+(H)+CH ₃提高了 MMA 形成的活性O+*→MMA 比 Au 调制的 Pd 和纯 Au(Pd) 催化剂。此外，Pd 调制的 Au 催化剂的直接氧化酯化具有更好的催化性能（稳定性和活性），具有更高的调制 Pd 原子覆盖率归因于表面原子的平均电荷较少，并且与纯催化剂相比，d 带中心接近费米能级。 Au(Pd)和Au调制的Pd催化剂。因此，提出 Pd 调制的 Au 催化剂有望用于甲基丙烯醛与甲醇的直接氧化酯化反应生成甲基丙烯酸甲酯。该研究不仅有助于理解双金属Pd-Au催化剂直接氧化酯化机理的理论，而且为设计用于直接氧化酯化的高效双金属Pd-Au催化剂提供线索。