Near-Surface Gas-Phase Methoxymethanol Is Generated by Methanol Oxidation over Pd-Based Catalysts.
Near-Surface Gas-Phase Methoxymethanol Is Generated by Methanol Oxidation over Pd-Based Catalysts.
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DOI：
10.1021/acs.jpclett.1c03381
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发表时间：
2021-11
期刊：
影响因子：
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通讯作者：
Sadi M Gurses;Trevor Price;Angie J. Zhang;J. Frank;N. Hansen;D. Osborn;A. Kulkarni;C. Kronawitter
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文献类型：
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作者：
Sadi M Gurses;Trevor Price;Angie J. Zhang;J. Frank;N. Hansen;D. Osborn;A. Kulkarni;C. Kronawitter
醇的催化转化是许多商品和精细化学品合成的基础，但缺乏完整的机理理解。采用小孔径分子束飞行时间质谱技术研究了常压下甲醇的催化氧化转化，考察了Pd基催化剂表面500 μm处的气相。除了各种稳定的C1-3物种，我们检测到甲氧基甲醇（CH 3 OCH 2 OH）-一个很少观察到的和反应性的C2醇，已被认为是甲酸甲酯生产的关键中间体。在Pd、Pd/Pdy合金和氧化物负载的Pd（常见的甲醇氧化催化剂）上观察到甲氧基甲醇。实验建立温度和反应物进料比的依赖性甲氧基甲醇的产生，并使用密度泛函理论的计算被用来检查其可能的形成途径的能量学。这些结果表明，甲醇氧化的催化剂和微观动力学模型的未来发展，应加强和约束，以适应形成，解吸，吸附和表面反应，涉及甲氧基甲醇。
Catalytic conversion of alcohols underlies many commodity and fine chemical syntheses, but a complete mechanistic understanding is lacking. We examined catalytic oxidative conversion of methanol near atmospheric pressure using operando small-aperture molecular beam time-of-flight mass spectrometry, interrogating the gas phase 500 μm above Pd-based catalyst surfaces. In addition to a variety of stable C1-3 species, we detected methoxymethanol (CH3OCH2OH)─a rarely observed and reactive C2 oxygenate that has been proposed to be a critical intermediate in methyl formate production. Methoxymethanol is observed above Pd, AuxPdy alloys, and oxide-supported Pd (common methanol oxidation catalysts). Experiments establish temperature and reactant feed ratio dependences of methoxymethanol generation, and calculations using density functional theory are used to examine the energetics of its likely formation pathway. These results suggest that future development of catalysts and microkinetic models for methanol oxidation should be augmented and constrained to accommodate the formation, desorption, adsorption, and surface reactions involving methoxymethanol.