Abstract Fundamental understanding of basic site of supported metal catalysts is highly desirable for aqueous phase oxidation of alcohols without adding extra alkali. Herein, nanoscale alkaline earth metals doped Pt/M−MCM−41 catalysts (M = Mg, Ca, Sr and Ba) were prepared for the aqueous phase oxidation of glycerol to glyceric acid in base-free medium. By establishing the correlation between basic active site and catalytic performance, it is found that catalytic activity increases almost linearly with the strength of basic sites, and excessively strong basic sites are not conducive to the improvement of glyceric acid selectivity. Multi-characterizations revealed that strong basic sites generated by alkaline earth metal oxides (especially MgO and CaO) could induce the enhanced electronic transfer ability, the modified reduction properties of Pt and abundant surface oxygen vacancies in the Pt/M−MCM−41 catalysts. Moreover, reaction kinetics demonstrated that the addition of alkaline earth metal oxides (e.g. CaO) could promote the activation of primary hydroxyl group and C-H bond, resulting in the excellent catalytic performance. In addition, as the representative of the optimal solid base catalysts, the Pt/Ca-MCM-41 (70) catalyst also exhibits record high turnover frequency (TOF) values for the oxidation of glucose (9623.0 h−1) and xylose (4561.0 h−1) to corresponding carboxylic acids.

中文翻译：

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深入了解甘油水相氧化成甘油酸中的基本强度依赖性催化性能

摘要 对负载型金属催化剂的碱性位点的基本了解对于醇的水相氧化而不添加额外的碱是非常需要的。在此，制备了纳米级碱土金属掺杂的 Pt/M-MCM-41 催化剂（M = Mg、Ca、Sr 和 Ba），用于在无碱介质中将甘油水相氧化为甘油。通过建立碱性活性位点与催化性能的相关性发现，催化活性几乎随碱性位点强度呈线性增加，碱性位点过强不利于甘油酸选择性的提高。多重表征表明，碱土金属氧化物（尤其是 MgO 和 CaO）产生的强碱性位点可以诱导增强的电子转移能力，Pt/M-MCM-41 催化剂中 Pt 的改性还原性能和丰富的表面氧空位。此外，反应动力学表明，碱土金属氧化物（如CaO）的加入可以促进伯羟基和CH键的活化，从而获得优异的催化性能。此外，作为最佳固体碱催化剂的代表，Pt/Ca-MCM-41 (70) 催化剂还表现出葡萄糖 (9623.0 h-1) 和木糖 (4561.0) 氧化的高周转频率 (TOF) 值h-1) 对应的羧酸。从而产生优异的催化性能。此外，作为最佳固体碱催化剂的代表，Pt/Ca-MCM-41 (70) 催化剂还表现出葡萄糖 (9623.0 h-1) 和木糖 (4561.0) 氧化的高周转频率 (TOF) 值h-1) 对应的羧酸。从而产生优异的催化性能。此外，作为最佳固体碱催化剂的代表，Pt/Ca-MCM-41 (70) 催化剂还表现出葡萄糖 (9623.0 h-1) 和木糖 (4561.0) 氧化的高周转频率 (TOF) 值h-1) 对应的羧酸。