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Synthesis and Catalytic Properties of Mesoporous Carbon Materials

Author: LiuYu
Tutor: JiaMingJun；ZhangWenXiang
School: Jilin University
Course: Physical and chemical
Keywords: mesoporous carbon carbon monolith oxidation of benzyl alcohol hard template method
CLC: O643.36
Type: Master's thesis
Year: 2008
Downloads: 346
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Abstract

Mesoporous carbon materials with high specific surface areas, uniformity poresize distributions, good mechanical stability and high electronic conductivity areof great interest for their important potential applications in many fields such asseparation, catalysis, biology and electronics. Recently , more attention has beenfocused on the synthesis and application of mesoporous carbon materials.Hard template route is widely used for the synthesis of mesoporous carbonmaterials. This method generally involves the in filtration of carbon precursor intothe template pores, carbonization and template removal. However, a maindrawback of the silica template route is that the pore structures of the carbonmaterials are usually generated via removing the silica template by usinghydrofluoric or caustic base. This synthesis process is complicated and costly.Besides, the tuning of porous characteristics (e.g. proe size) of carbon materials isalso difficult by using silica template route. Therefore, it is still an attractive subject to develop simple method to synthesize the mesoporous carbon and theirapplication in catalysis and electrochemistry.In this work, we report a simple and efficient route to synthesize mesoporouscarbon material via direct carbonizing composite of as-synthesized AlPO. Theresultant carbon exhibits high surface area and uniform pore size distribution. Wefound that the characteristics of porous carbon materials, such as surface area,pore size and pore volume, can be easily tuned in a certain range by introducing apart of sugar. The reaction of catalytic oxidation of benzyl alcohol is carried out toinvestigate the catalytic performances of mesoporous carbon materials. Thecarbon material named NC-2, which is synthesized from citric acid and sugar ascarbon precursor, shows the highest activity (71.2% conversion of benzyl alcohol).The effects of different synthetic method and reactive conditions on the catalyticperformances of mesoporous carbon material have also been systemicallyinvestigated. The catalytic results suggest that the presence of surface oxygengroups on the surface of mesoporous carbon might play an important role on theoxidation of benzyl alcohol .Mesoporous carbon with monolithic structure has been synthesized by directcarbonization of compressed sucrose/silica composite, which is prepared by usingsol-gel method. The resultant carbon monoliths possess relatively high surfacearea, large pore volume and well interconnected pore system. Interestingly, thestructural and textural parameters of the carbon monolith could be adjusted withina certain range by introducing a certain amount of citric acid (CA), phosphoricacid or aluminum nitrate into the sol -gel precursor of sucrose/silica composite.For examples, the average pore size of resultant c arbon monolith increases (f rom2.5~4.1) with the increase of CA/Si ratio from 0.1 to 1.0. When adding phosphoric acid, the change of the average pore size of carbon monoliths showsthe similar trend. The additive of aluminum nitrate could increase the BET surfacearea of carbon monolith. With the increase of Al/Si ratio from 0.1 to 0.5, thesurface area increases from 1820 to 2871 m2g-1. These carbon monoliths exhibitrelatively high catalytic performances in the selective oxidation of benzyl alcohol,and the sample of CM-P4 (P/Si=0.5) shows the highest activity (96.4%conversion of benzyl alcohol). These results suggest that such kind of carbonmonolith may have potential application in the field of catalysis.

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