The hydrogenation of aromatic amines to the corresponding cycloaliphatic primary amines is an important industrial reaction. However, secondary amine formation and other side reactions are frequently observed, resulting in reduced selectivity. The side products are formed mostly on the support, yet support effects are little understood at present. This study describes the facile modification of Ru/CNT catalysts with LiOH, by this means significantly improving catalyst selectivity in toluidine hydrogenation without decreasing the activity of the catalysts. The effect is explained by LiOH diminishing acidic sites on the catalyst support and enhancing the adsorption of the aromatic ring on the metallic ruthenium nanoparticles. With the LiOH‐modified Ru/CNT catalyst, other substrates, such as methylnitrobenzenes, are also converted efficiently. This study thus describes an improved catalyst for the preparation of cyclohexylamines and provides guidelines for future catalyst design.

中文翻译：

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锂修饰的Ru / CNT催化剂上苯胺加氢成环脂族伯胺的选择性提高

芳族胺加氢为相应的脂环族伯胺是重要的工业反应。但是，经常观察到仲胺的形成和其他副反应，导致选择性降低。副产物主要在载体上形成，但是目前对载体的作用了解甚少。这项研究描述了用LiOH轻松修饰Ru / CNT催化剂的方法，通过这种方法可以显着提高甲苯胺加氢中催化剂的选择性，而不会降低催化剂的活性。LiOH减少了催化剂载体上的酸性位并增强了芳环在金属钌纳米粒子上的吸附，从而解释了这种效果。使用LiOH改性的Ru / CNT催化剂，还可以有效地转化其他底物，例如甲基硝基苯。