US EPA

3073825 

Journal Article 

Guanidine Nitrate Enhanced Catalysis of Nitrogen-Doped Carbon Nanotubes for Metal-Free Styrene Production through Direct Dehydrogenation 

Zhao, Z; Dai, Y; Ge, G; Wang, G 

2015 

Yes 

ChemCatChem
ISSN: 1867-3880
EISSN: GmbH & Co. KGaA 

7 

7 

1135-1144 

English 

10.1002/cctc.201402934 

WOS:000352488300014 

https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027934860&doi=10.1002%2fcctc.201402934&partnerID=40&md5=bc227276e83889bcd59405fd660f420b
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Nitrogen-doped carbon nanotubes (CNTs) with defect- and CO-group-rich surface features were fabricated through a facile and scalable physical dry milling and subsequent pyrolysis approach of carbon nanotubes and melamine in the presence of guanidine nitrate. The catalytic performance of the as-prepared N-doped CNTs with diverse guanidine nitrate dosages and pyrolysis temperatures for direct dehydrogenation of ethylbenzene to styrene under oxidant- and steam-free conditions was measured. Various characterization techniques including high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen-adsorption and thermogravimetric analysis, and Raman spectroscopy were employed to investigate the structure and surface properties, as well as to explore the relationship between catalyst nature and catalytic performance. It is found that the addition of guanidine nitrate in the pyrolysis process of CNT with melamine significantly affects the structure, surface properties, and catalytic performance. The optimized N-doped CNTs demonstrate steady-state styrene production rates 1.56 and 1.60 times higher than those of the parent CNTs and the established nanodiamond, as well as 6.49 times the rate of commercially available K-Fe catalyst without compromising the selectivity to styrene. The much superior catalytic performance in metal-free catalytic direct dehydrogenation can be ascribed to the CO group- and defect-rich surface nature, the basic properties resulted from N-doping, the larger surface area and pore volume, and smaller graphitic carbon crystallites. The fabricated novel N-doped CNTs can be considered as a promising candidate for sustainable production of styrene through oxidant- and steam-free direct dehydrogenation of ethylbenzene with energy-saving and environmentally benign features. The developed defect-formation strategy in this work can be used for preparation of other metal-free carbocatalysts. 

carbon; dehydrogenation; doping; nanotubes; nitrogen