中国科学技术大学曾杰团队报道了低温羟基氧化甲烷高选择性合成乙酸。相关研究成果于2024年9月2日发表在《德国应用化学》。

直接甲烷转化，特别是好氧氧化制乙酸，仍然是一个突出的挑战。

该文中，研究人员报道了一种沸石负载的Au-Fe催化剂（Au-Fe/ZSM-5），它在CO的存在下用分子氧作为氧化剂将甲烷转化为乙酸。具体来说，Au纳米粒子催化CO、O₂和H₂O反应形成羟基物种，同时ZSM-5负载的原子分散的Fe物种负责CH₄和CO的羟基介导偶联以产生乙酸。

在62bar（CH₄:CO:O₂=14:14:3）和120°C下，在50毫克Au-Fe/ZSM-5上反应3.0小时，每克催化剂产生5.7毫摩尔乙酸（mmol gcat^-1），选择性为92%，优于大多数报道的催化剂。值得注意的是，催化剂即使在60°C下也保持活性。

研究认为这种羟基介导的路线可能会指导低温下，直接甲烷官能化的优化催化剂的设计。

附：英文原文

Title: Highly Selective Synthesis of Acetic Acid from Hydroxyl-Mediated Oxidation of Methane at Low Temperatures

Author: Bo Wu, Haibin Yin, Xinlong Ma, Rongjia Liu, Bingxuan He, Hongliang Li, Jie Zeng

Issue&Volume: 2024-09-02

Abstract: Direct methane conversion and, in particular, the aerobic oxidation to acetic acid, remain an eminent challenge. Here, we reported a zeolite-supported Au-Fe catalyst (Au-Fe/ZSM-5) that converted methane to acetic acid with molecular oxygen as an oxidant in the presence of CO. Specifically, Au nanoparticles catalyzed the formation of hydroxyl species from the reaction of CO, O2, and H2O, meanwhile ZSM-5-supported atomically dispersed Fe species were responsible for the hydroxyl-mediated coupling of CH4 and CO to generate acetic acid. The reaction over 50 mg of Au-Fe/ZSM-5 under 62 bar (CH4: CO: O2 = 14: 14: 3) at 120 °C for 3.0 h yielded 5.7 millimoles of acetic acid per gram of the catalyst (mmol gcat-1) with the selectivity of 92%, outperformed most of reported catalysts. Significantly, the catalyst remained active even at 60 °C. We anticipate that this hydroxyl-mediated route may guide the design of optimized catalysts for the direct methane functionalization at low temperatures.

DOI: 10.1002/anie.202412995

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202412995