Controlling regioselectivity in lactic acid conversion is a key for production of bio-based chemicals due to bio-lactic acid molecule containing active bifunctional groups such as hydroxyl (–OH) and carboxyl (–COOH). Here, we report that the Ru-stabilized MoO_3-x overlayers with rich oxygen vacancies overturn lactic acid hydrogenation regioselectivity to propionic acid (PA) via C-OH hydrodeoxygenation, achieving a high PA selectivity of 95.9%, which is completely different from the catalytic feature of the Ru particle surfaces with dominating 1,2-propanediol selectivity through hydrogenation of –COOH. Furthermore, the activity on the encapsulating oxide layers can be extended to other hydroxy acids such as glycolic acid, 3-hydroxypropionic acid, and DL-2-hydroxybutylic acid to generate their corresponding carboxylic acids, displaying a unique ability for hydrodeoxygenation of –OH group. The encapsulating oxide layers with rich oxygen vacancies can be dynamically generated in the presence of the reductive atmosphere such as H₂-Ar mixture, and efficiently stabilized by Ru nanoparticles, thus endowing more excellent activity of Ru-MoO_3-x than that of MoO₃, MoO_3-x and Ru-MoO₃. Encouragingly, lactic acid conversion and propionic acid selectivity have hardly decayed during running 5 cycles due to Ru-stabilized MoO_3-x overlayers. This work provides an efficient strategy for constructing the defective encapsulation oxide layers with rich oxygen vacancies, which helps to produce the desired bio-based chemical of PA from bio-lactic acid.

中文翻译：

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通过 Ru 稳定的 MoO3-x 外层翻转乳酸加氢区域选择性


由于生物乳酸分子含有羟基 （-OH） 和羧基 （-COOH） 等活性双功能基团，因此控制乳酸转化中的区域选择性是生产生物基化学品的关键。在这里，我们报道了具有丰富氧空位的 Ru 稳定 MoO_3-x 上层通过 C-OH 加氢脱氧颠覆了乳酸加氢区域选择性为丙酸 （PA），实现了 95.9% 的高 PA 选择性，这与 Ru 颗粒表面通过 –COOH 加氢占主导地位的 1,2-丙二醇选择性完全不同。此外，包封氧化物层上的活性可以扩展到其他羟基酸，如乙醇酸、3-羟基丙酸和 DL-2-羟基丁酸，以生成它们相应的羧酸，显示出 –OH 基团加氢脱氧的独特能力。在 H_2-Ar 混合物等还原气氛存在下，可以动态生成具有丰富氧空位的包封氧化层，并被 Ru 纳米颗粒有效稳定，从而赋予 Ru-MoO_3-x 比 MoO₃、MoO_3-x 和 Ru-MoO₃ 更优异的活性。令人鼓舞的是，由于 Ru 稳定的 MoO_3-x 覆盖层，乳酸转化率和丙酸选择性在运行 5 个循环期间几乎没有衰减。这项工作为构建具有丰富氧空位的有缺陷的包埋氧化物层提供了一种有效的策略，这有助于从生物乳酸中生产所需的生物基化学品 PA。