高精度合成具有可控晶面的α-MnO2纳米线用于丙烷氧化,CrystEngComm

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高精度合成具有可控晶面的α-MnO2纳米线用于丙烷氧化
CrystEngComm ( IF 2.6 ) Pub Date : 2021-10-04 , DOI: 10.1039/d1ce01044a
Chao Feng ₁ , Gaoyan Xiong ₁ , Yaping Li ₂ , Qianqian Gao ₁ , Yuan Pan ₁ , Zhaoyang Fei ₃ , Yanpeng Li ₁ , Yukun Lu ₂ , Chenguang Liu ₁ , Yunqi Liu ₁

Affiliation

确定晶面对反应性能的影响对于设计有效的丙烷氧化催化剂至关重要。在此，提出了具有暴露的（110）、（211）、（310）和（200）晶面的α-MnO ₂纳米线，并研究了它们对丙烷氧化的晶面依赖性反应性。所得的α-MnO ₂纳米线具有主要暴露的（110）面，显示出最大的丙烷氧化活性（T ₉₀ = 262.1 °C）、氧化速率和周转频率（230 °C），以及丙烷氧化过程中的高稳定性. 就地漫反射红外傅里叶变换光谱表明，氧化形成羧酸盐是决定性步骤；因此，活性氧的产生非常重要。态密度计算的结果表明，最低的电子能量存在于 (110) 面，这有助于产生活性氧物质和调节 Mn 的表面价态。表征和计算结果表明，(110)晶面有利于形成氧空位，使O ₂和丙烷活化和吸附，从而显着提高丙烷氧化活性。除了提供关于 α-MnO ₂的构效关系的新见解由于暴露于短链挥发性氧化反应的不同方面，本研究提出了一种可用于改进其他锰基催化剂氧化系统的技术。

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High-precision synthesis of α-MnO2 nanowires with controllable crystal facets for propane oxidation

Determining the effect of crystal facets on reaction performance is essential for designing an efficient propane oxidation catalyst. Herein, α-MnO₂ nanowires with exposed (110), (211), (310) and (200) facets were proposed, and their crystal facet-dependent reactivity to propane oxidation was investigated. The resultant α-MnO₂ nanowires with predominantly exposed (110) facets showed the maximum propane oxidation activity (T₉₀ = 262.1 °C), oxidation rate, and turnover frequency (at 230 °C), and high stability during the oxidation of propane. In situ diffuse reflectance infrared Fourier transform spectroscopy revealed that the oxidation to form carboxylates is the decisive step; therefore, the production of reactive oxygen species is very important. The results from density of states computations revealed that the lowest electron energy was present in the (110) facet, which helps in the generation of reactive oxygen species and the regulation of the surface valence of Mn. The characterization and calculation results indicated that the (110) facets are conducive to forming oxygen vacancies, which allowed the activation and adsorption of O₂ and propane, resulting in significantly enhanced propane oxidation activity. Apart from offering new insights about the structure–activity relationship of α-MnO₂ with different facets exposed for short-chain volatile oxidation reactions, this study proposes a technique that can be used for improving other manganese-based catalyst oxidation systems.

更新日期：2021-10-18

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