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以不同的酚醛树脂为原料经催化热解法制备碳纳米管时结果差异较大,为阐明存在的问题及原因,以酚醛树脂为碳源、硝酸铁为催化剂前驱体,通过催化酚醛树脂裂解的方法制备碳纳米管,研究了酚醛树脂中孔结构对合成碳纳米管的影响。采用X射线衍射、扫描电子显微镜和透射电子显微镜对酚醛树脂热解产物的物相组成及显微结构进行了分析。结果表明:1)碳纳米管仅生长在固化后酚醛树脂的大气孔(50~1 000μm)中,其直径约为40~100纳米,长度可达几百微米,其它位置基本无碳纳米管的生成;2)较大的气孔(50~1 000μm)可为碳纳米管的生长提供相对充足的碳源和生长空间,继而有利于碳纳米管的生成;3)较小的气孔(30μm以下)由于难以满足该条件而基本无碳纳米管的生成。碳纳米管的产率与酚醛树脂固化后形成气孔的大小有关,采用固化后能形成较大孔径的酚醛树脂为碳源可以提高碳纳米管的产率。
In order to elucidate the existing problems and reasons, different phenolic resins were used as raw materials to produce carbon nanotubes by catalytic pyrolysis. The results showed that phenolic resin as carbon source and ferric nitrate as catalyst precursors could catalyze the cracking of phenolic resin Methods Carbon nanotubes were prepared and the effects of mesoporous structure of phenolic resin on the synthesis of carbon nanotubes were investigated. The phase composition and microstructure of pyrolysis products of phenolic resin were analyzed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that: 1) CNTs grow only in the pores (50 ~ 1 000 μm) of phenolic resin after curing, with diameter of 40-100 nm and length of up to several hundred micrometers, with no carbon nanotubes in other positions (50 ~ 1 000μm) can provide relatively sufficient carbon source and growth space for the growth of carbon nanotubes, which in turn is conducive to the formation of carbon nanotubes; 3) smaller pores (less than 30μm) Since it is difficult to satisfy this condition, almost no generation of carbon nanotubes occurs. The yield of carbon nanotubes is related to the size of the pores formed after the curing of the phenolic resin. Using a phenolic resin which can form a larger pore size after curing can improve the yield of carbon nanotubes.