Formation of carbon nanotubes through ethylene decomposition over supported Pt catalysts and silica-coated Pt catalysts
Formation of carbon nanotubes through ethylene decomposition over supported Pt catalysts and silica-coated Pt catalysts
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DOI：
10.1016/j.carbon.2008.12.051
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发表时间：
2009-04
期刊：
影响因子：
10.9
通讯作者：
S. Takenaka;T. Iguchi;E. Tanabe;H. Matsune;M. Kishida
中科院分区：
文献类型：
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作者：
S. Takenaka;T. Iguchi;E. Tanabe;H. Matsune;M. Kishida
在负载型Pt催化剂上进行乙烯裂解反应，制备了Pt金属纳米颗粒和碳纳米管（CNTs）的复合物。所有负载型Pt催化剂（Pt/炭黑、Pt/CNT、Pt/MgO、Pt/Al 2 O3和Pt/SiO2）在973 K下均表现出催化乙烯裂解生成CNT的活性。Pt金属颗粒被发现在碳纳米管的尖端。这些结果表明Pt金属颗粒对通过烃分解生长CNT具有催化活性。尽管在乙烯分解之前催化剂中的Pt金属颗粒在尺寸上相对均匀（2- 5 nm），但是通过使用负载的Pt金属催化剂形成宽范围（5- 50 nm）的CNT直径。这些结果表明，在973 K下，催化剂中的Pt金属颗粒在乙烯分解过程中发生了聚集。在催化剂上覆盖几纳米厚的二氧化硅层，可以抑制催化剂中Pt金属粒子在乙烯分解过程中的聚集。二氧化硅包覆的Pt催化剂显示出高的乙烯分解活性，形成直径均匀（8- 10 nm）的碳纳米管，尽管Pt金属颗粒均匀覆盖有二氧化硅层。
Ethylene decomposition was performed over supported Pt catalysts to fabricate composites of Pt metal nanoparticles and carbon nanotubes (CNTs). All supported Pt catalysts (Pt/carbon black, Pt/CNT, Pt/MgO, Pt/Al2O3and Pt/SiO2) showed catalytic activity for ethylene decomposition at 973K to form CNTs. Pt metal particles were found at tips of CNTs. These results indicate that Pt metal particles have catalytic activity for growth of CNTs through hydrocarbon decomposition. A broad range (5–50nm) of CNT diameters were formed from the use of supported Pt metal catalysts although Pt metal particles in the catalysts before ethylene decomposition were relatively uniform in size (2–5nm). These results imply that Pt metal particles in the catalysts aggregated during ethylene decomposition at 973K. Aggregation of Pt metal particles in catalysts during ethylene decomposition could be suppressed by covering catalysts with silica layers that were a few nanometers thick. Silica-coated Pt catalysts showed high activity for ethylene decomposition to form CNTs with uniform diameters (8–10nm) despite the uniform coverage of Pt metal particles with silica layers.