Preparation And Study Of Micro-/Nano-carbon And Properities Of Supported-Pt Catalysts For Dehydrogenation Of Cyclohexane

Cyclohexane-benzene are one of potential candidates for hydrogen on-board storage and supply due to their advantages including high hydrogen storage density, recyclable and easy transportation. However, cyclohexane dehydrogenation requires highly effective catalyst. At present, low activity and stability of catalyst are still problems to be solved. Therefore, it is significant to develop highly efficient catalysts to improve the activity and stability.Presently, carbon materials are widely used as carrier materials due to their acid and alkaline resistant, easy recovery of noble metals and low cost.Particularly, the catalytic performance strongly depends on the morphologies and pore textures of carbon supports. Moreover, the work focuses on synthesis of novle carbon materials with different morphologies and structures. The catalytic properties of Pt-based catalysts for cyclohexane dehydrogenation were also studied. The contents and results are as follows:(1) Carbon microspheres with different sizes were sythesized by hydrothermal method. The effect of carbon mircosphere size and Pt loading on Pt-based catalysts in cyclohexane dehydrogenation were also investigated. Theresults show that the catalytic properties are strongly influenced by carbon mircosphere size and Pt loading. Particularly, the catalytic activity and stability are improved by decreasing the size of the carbon carrier. The TOF value is about 360 mmol·molPt-1·s-1after 5 h running. Cyclohexane conversions increase with increasing Pt contents from 0.5 to 1.5 wt. %, and Pt/C catalyst with 1.0wt. % Pt exihibits higher activity.(2) Nanocarbon materials with different morphologies were synthesized by hydrothermal method. The influence of different carbonization temperatures of supports, their morphologies and Pt loadings on catalytic properties were also studied. The results show that the surface area of nanocarbon material can be controlled by changing carbonization temperature. And then improve the catalyst properties. Catalystic performance is improved by tuning carbon morphologies. The catalystic activity increases as the order of carbon morphologies: carbon nanoblock > carbon nanorod > carbon nanosphere. The TOF values are 1291, 1267 and 1203 mmol·mol Pt-1·s-1, respectively after 5 h running. Catalystic properties are further improved by optimuming Pt loading.Cyclohexane conversion increases with increasing Pt loading.(3) The hollow carbon materails with different structures were prepared using hard template assisted method. The catalystic properties of Pt-supported on carbon treated with different carbonation temperatures were investigated. The results show that catalystic properties were obviously influenced by carbonation temperatures of support and Pt loading. The activities increase with increasingcarbonization temperatures of support. The cyclohexane conversions increase with increasing Pt loading. The catalyst with 0.5 wt.% Pt loading shows higher activity, and the TOF vaule is about 1176 mmol·molPt-1·s-1after 5 h running. The hollow carbon supported-Pt catalysts show excellent thermal stabilities.