Fabrication of Ag/Mn3O4 nano-architectures for the one-step selective oxidation of 3-picoline to niacin: a key to vitamin B3 production†,Catalysis Science & Technology

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Fabrication of Ag/Mn3O4 nano-architectures for the one-step selective oxidation of 3-picoline to niacin: a key to vitamin B3 production†
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2016-02-03 00:00:00 , DOI: 10.1039/c5cy02185e
Shilpi Ghosh _{1,

2,

3,

4} , Shankha S. Acharyya _{1,

2,

3,

4} , Sachin K. Sharma _{1,

2,

3,

4} , Rajaram Bal _{1,

2,

3,

4}

Affiliation

We have synthesized Ag nanoparticles (with sizes of 2–5 nm) supported on 1D Mn₃O₄ spinel nanorods by a surfactant-assisted single-step preparation method using a room-temperature synthesis protocol for the first time. The unique 1D rod-like morphology increases the amount of adsorption sites of the support, leading to less sintering and higher dispersion of Ag nanoparticles, resulting in significantly enhanced catalytic activity for the industrially important selective oxidation of 3-picoline to niacin. The catalyst was thoroughly characterized by XRD, XPS, SEM, TEM, Raman, FTIR and UV-visible spectroscopy. XRD revealed the formation of Ag nanoparticles supported on hausmannite-type tetragonal Mn₃O₄. Electron microscopy studies confirmed the formation of the 1D structure of the catalyst. The generation of this 1D nanostructure has been revealed in detail and correlated with its superior catalytic activity. Various reaction parameters like temperature, substrate : H₂O₂ molar ratio, reaction time, etc. were studied. A niacin selectivity of 97%, with a 3-picoline conversion of 55%, was achieved over this catalyst at 70 °C. It was noticed that, when halide ions (Br⁻) were present in the synthesis gel mixture, only then were the morphology and activity of the catalyst proven to be superior. The thorough dispersion of Ag nanoparticles on Mn₃O₄ nanorods and the synergy displayed between Ag nanoparticles and Mn₃O₄ are the detrimental factors for its high activity. The catalyst was reused 5 times and thereby displayed its true heterogeneous character.

中文翻译：

Ag / Mn ₃ O ₄纳米结构的制备，用于将3-甲基吡啶选择性氧化成烟酸：维生素B ₃产生的关键†

我们首次使用室温合成方案，通过表面活性剂辅助的一步制备方法合成了负载在1D Mn ₃ O ₄尖晶石纳米棒上的Ag纳米颗粒（尺寸为2–5 nm）。独特的1D棒状形态增加了载体的吸附位点数量，从而减少了烧结并提高了Ag纳米颗粒的分散度，从而显着增强了对工业上重要的3-甲基吡啶向烟酸的选择性氧化的催化活性。通过XRD，XPS，SEM，TEM，拉曼光谱，FTIR和紫外可见光谱对催化剂进行了全面表征。X射线衍射揭示了负载在mannmann型四方Mn ₃ O ₄上的Ag纳米颗粒的形成。电子显微镜研究证实了催化剂的一维结构的形成。一维纳米结构的产生已被详细揭示，并与其优越的催化活性相关。研究了各种反应参数，例如温度，底物：H ₂ O ₂摩尔比，反应时间等。在70℃下，在该催化剂上烟酸的选择性达到97％，3-甲基吡啶的转化率为55％。可以注意到的是，当卤化物离子（BR ^-）存在于合成凝胶混合物，才被证明是优异的催化剂的形态和活性。Ag纳米颗粒在Mn ₃ O ₄上的彻底分散纳米棒以及Ag纳米颗粒与Mn ₃ O ₄之间表现出的协同作用是其高活性的不利因素。该催化剂被重复使用5次，从而显示出其真正的非均质特征。

更新日期：2016-02-03

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