中国科学院化学研究所Buxing Han小组在研究中取得进展。他们提出了酮介导硝酸盐电还原合成羟胺的研究。相关论文于2024年4月6日发表在《美国化学会杂志》上。

在该研究中，该课题组报道了在水中用硝酸盐的酮介导的羟胺（HA）合成的第一项工作。他们开发了一种金属-有机骨架衍生的Cu催化剂来催化该反应。环戊酮(CP)在原位捕获HA形成具有C = N键的CP肟(CP-O)，该键易于水解。电解后HA容易释放，CP再生。结果表明，CP-O的法拉第效率为47.8%，相应的生成速率为34.9 mg h^-1 cm^-2，碳选择性为99.9%。

他们优化了CP-O水解释放HA和CP再生的工艺，使溶液中的HA稳定在96.1 mmol L^-1，显著高于直接还原硝酸盐。详细的原位表征、控制实验和理论计算揭示了催化剂的表面重构和反应机理，表明Cu⁰和Cu⁺的共存促进了*NO₂和*NH₂OH的质子化和还原，从而增强了HA的生成。

据悉，羟胺(HA, NH₂OH)是多种化工原料生产的重要原料，其高效、可持续的合成具有重要意义。在铜基催化剂上电还原硝酸盐已成为一种很有前途的绿色氨(NH₃)生产方法，但由于HA过度还原为NH₃，电合成HA仍然具有挑战性。

附：英文原文

Title: Synthesis of Hydroxylamine via Ketone-Mediated Nitrate Electroreduction

Author: Shunhan Jia, Limin Wu, Xingxing Tan, Jiaqi Feng, Xiaodong Ma, Libing Zhang, Xinning Song, Liang Xu, Qinggong Zhu, Xinchen Kang, Xiaofu Sun, Buxing Han

Issue&Volume: April 6, 2024

Abstract: Hydroxylamine (HA, NH2OH) is a critical feedstock in the production of various chemicals and materials, and its efficient and sustainable synthesis is of great importance. Electroreduction of nitrate on Cu-based catalysts has emerged as a promising approach for green ammonia (NH3) production, but the electrosynthesis of HA remains challenging due to overreduction of HA to NH3. Herein, we report the first work on ketone-mediated HA synthesis using nitrate in water. A metal–organic-framework-derived Cu catalyst was developed to catalyze the reaction. Cyclopentanone (CP) was used to capture HA in situ to form CP oxime (CP-O) with C═N bonds, which is prone to hydrolysis. HA could be released easily after electrolysis, and CP was regenerated. It was demonstrated that CP-O could be formed with an excellent Faradaic efficiency of 47.8%, a corresponding formation rate of 34.9 mg h–1 cm–2, and a remarkable carbon selectivity of >99.9%. The hydrolysis of CP-O to release HA and CP regeneration was also optimized, resulting in 96.1 mmol L–1 of HA stabilized in the solution, which was significantly higher than direct nitrate reduction. Detailed in situ characterizations, control experiments, and theoretical calculations revealed the catalyst surface reconstruction and reaction mechanism, which showed that the coexistence of Cu0 and Cu+ facilitated the protonation and reduction of *NO2 and *NH2OH desorption, leading to the enhancement for HA production.

DOI: 10.1021/jacs.4c01961

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c01961