Nitrogen-doped nanotubes-decorated activated carbon-based hybrid nanoarchitecture as a superior catalyst for direct dehydrogenation

Zhao Zhongkui; Dai Yitao; Ge Guifang

摘要

A novel N-doped activated carbon (AC) based nanostructure decorated with nanotubes (N-CNT-AC) has been successfully fabricated through a facile and scalable approach involving the mechanical milling and subsequent solid pyrolysis of the low-cost and commercially available AC and melamine. Various characterization techniques including high resolution transmission electron microscopy, X-ray diffraction, nitrogen adsorption, X-ray photoelectron spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy were employed to reveal the relationship between catalyst features and catalytic performance in the oxidant-and steam-free direct dehydrogenation (DDH) of ethylbenzene to styrene. Although the as-synthesized AC-based hybrid nanostructure has a much lower surface area (397.0 cm(2) g(-1)) and pore volume (0.17 cm(3) g(-1)) than the parent AC (777.1 cm(2) g(-1) surface area and 0.4 cm(3) g(-1) pore volume), it demonstrates 1.74 and 3.67 times the steady-state styrene rate of the per gram parent AC and the industrially-used K-Fe catalyst, respectively, for the DDH reaction, which is ascribed to the promoting effect of the unique hybrid microstructure, the surface rich C=O group and defect/edge feature, the increased basic properties through N-introduction into the hybrid nanostructure, the small size of the graphitic crystallite, as well as the inherent high surface and large porosity of the AC-based materials. The in situ Fourier transform infrared spectroscopy measurement suggests a lower activation energy over the developed novel N-doped AC-based hybrid nanostructure for the DDH reaction than over the parent AC. Interestingly, the developed hybrid nanocomposite exhibits a much superior selectivity for styrene production compared to the parent AC, which is ascribed to the N-doping into the AC-based matrix. The developed N-doped AC-based hybrid nanostructure catalyst could be a potential candidate for catalytic styrene production via steam-and oxidant-free direct dehydrogenation of ethylbenzene.

机译：一种新型的基于纳米管（N-CNT-AC）装饰的基于N掺杂的活性炭（AC）纳米结构已通过涉及机械铣削以及随后的低成本和市售AC和市售AC和市值的固体热解成功地制造了。三聚氰胺。各种表征技术，包括高分辨率透射电子显微镜，X射线衍射，氮气吸附，X射线光电子光谱，拉曼光谱和傅立叶变换红外光谱法被用来揭示催化剂和氧化剂和蒸汽 - 蒸汽和蒸汽 - - 蒸汽和蒸汽 - 催化性能之间的关系乙烯苯苯乙烯的自由直接脱氢（DDH）。尽管基于AC的AC杂种纳米结构的表面积（397.0 cm（2）g（-1））和孔体积（0.17 cm（3）g（-1））比母体AC（777.1 cm（777.1 cm）低得多。（2）G（-1）表面积和0.4 cm（3）g（-1）孔体积），它显示出每克母体AC的稳态苯乙烯速率和工业用k-的稳态苯乙烯速率的1.74和3.67倍DDH反应分别归因于独特杂交微观结构的促进作用，表面富的C = O组和缺陷/边缘特征，通过N介导向杂交纳米结构，增加的基本特性，是杂种纳米结构，增加的基本特性，石墨结晶石的小尺寸以及基于交流的材料的固有高表面和较大的孔隙率。原位傅立叶变换红外光谱测量表明，与母体AC相比，发达的新型N掺杂基于AC的基于N型AC的杂交纳米结构的活化能较低。有趣的是，与母体AC相比，开发的杂化纳米复合材料对苯乙烯产生的选择性优于，这是归因于N掺杂到基于AC的基质的。开发的基于N掺杂的AC的杂化纳米结构催化剂可能是通过乙烯乙烯的无蒸汽和无氧化剂直接脱氢作用来催化苯乙烯产生的潜在候选者。

Nitrogen-doped nanotubes-decorated activated carbon-based hybrid nanoarchitecture as a superior catalyst for direct dehydrogenation

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