Formation of carbon nanotubes through ethylene decomposition over supported Pt catalysts and silica-coated Pt catalysts

• Published in: Carbon (New York) Vol. 47; no. 5; pp. 1251 - 1257
• Main Authors: Takenaka, Sakae, Iguchi, Toshiyuki, Tanabe, Eishi, Matsune, Hideki, Kishida, Masahiro
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2009; Elsevier
• Subjects: Carbon nanotubes; Catalysis; Catalysts; Chemistry; Colloidal state and disperse state; Cross-disciplinary physics: materials science; rheology; Decomposition; Ethylene; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; General and physical chemistry; Materials science; Metal particles; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Physics; Platinum; Silicon dioxide; Specific materials; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Catalytic reaction; Carbon black; Growth; Magnesium oxide; Ethylene; Hydrocarbons; Carbon nanotubes; Binary compounds; Decomposition; Metal particle; Silica; Supported catalyst; Aggregation; Nanoparticles; Heterogeneous catalysis; Composite materials; Silicon oxides; Catalyst activity; Diameter
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2008.12.051

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/Al 2O 3 and Pt/SiO 2) showed catalytic activity for ethylene decomposition at 973 K 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 (5–50 nm) 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 (2–5 nm). These results imply that Pt metal particles in the catalysts aggregated during ethylene decomposition at 973 K. 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 (8–10 nm) despite the uniform coverage of Pt metal particles with silica layers.