Support materials play vital roles in heterogenous catalysis via the so-called support effects, and understanding on the support effects is beneficial for the design of high-performance catalysts. Herein, we represent detailed investigations on the support effects of Ag catalysts for dimethyl glycolate (DMO) semi-hydrogenation to methyl glycolate (MG), where G6 silica with amorphous mesopores, SBA-15 with parallel mesopores and silica nanospheres (MSNS) with center-radial ones were employed as the supports. The hydrogenation activity decreases in the order of Ag/MSNS > Ag/SBA-15 > Ag/G6 while the MG selectivity in the order of Ag/G6 > Ag/MSNS > Ag/SBA-15 at the same reaction conditions, indicating remarkable support effects on both activity and selectivity. Structural characterizations, temperature programmed experiments and FTIR of DMO adsorption experiments demonstrate that the weak confinement effect of G6 leads to the larger sized Ag nanoparticles and weakened activation of DMO and H, which contributes to low hydrogenation activity. In contrast, the ordered mesoporous SBA-15 and MSNS deliver well confinement effects for Ag nanoparticles and the activation of DMO and H, but the distinct pore structures result in different activation and diffusion behaviors. Finally, DMO conversion and MG yield are well correlated with the competitive adsorption of H versus DMO on Ag catalysts, indicating such competitivity as a descriptor for DMO semi-hydrogenation over Ag catalysts.

中文翻译：

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深入探讨Ag/SiO2催化剂对乙醇酸二甲酯半加氢制乙醇酸甲酯的支撑作用

载体材料通过所谓的载体效应在多相催化中发挥着至关重要的作用，对载体效应的理解有利于高性能催化剂的设计。在此，我们详细研究了银催化剂对乙醇酸二甲酯（DMO）半加氢生成乙醇酸甲酯（MG）的支撑作用，其中具有无定形介孔的G6二氧化硅、具有平行介孔的SBA-15和具有中心的二氧化硅纳米球（MSNS） -采用径向支撑件作为支撑件。相同反应条件下，加氢活性依次降低为 Ag/MSNS > Ag/SBA-15 > Ag/G6，而 MG 选择性则为 Ag/G6 > Ag/MSNS > Ag/SBA-15，表明显着。支持对活性和选择性的影响。 DMO 吸附实验的结构表征、程序升温实验和 FTIR 实验表明，G6 的弱限域效应导致 Ag 纳米粒子尺寸较大，DMO 和 H 的活化减弱，从而导致加氢活性较低。相比之下，有序介孔SBA-15和MSNS对Ag纳米颗粒以及DMO和H的活化具有良好的限制作用，但不同的孔结构导致不同的活化和扩散行为。最后，DMO 转化率和 MG 产率与 H 与 DMO 在 Ag 催化剂上的竞争吸附密切相关，表明这种竞争性作为 Ag 催化剂上 DMO 半加氢的描述符。