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The Combined Catalytic Action of Solid Acids with Nickel for the Transformation of Polypropylene into Carbon Nanotubes by Pyrolysis
Author(s) -
Song Rongjun,
Jiang Zhiwei,
Bi Wuguo,
Cheng Wenxi,
Lu Jun,
Huang Baotong,
Tang Tao
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200601018
Subject(s) - polypropylene , pyrolysis , nickel , catalysis , materials science , carbon nanotube , carbon fibers , chemical engineering , transformation (genetics) , chemistry , organic chemistry , nanotechnology , composite material , metallurgy , composite number , engineering , biochemistry , gene
The effects of both organically modified montmorillonite (OMMT) and Ni 2 O 3 on the carbonization of polypropylene (PP) during pyrolysis were investigated. The results from TEM and Raman spectroscopy showed that the carbonized products of PP were mainly multiwalled carbon nanotubes (MWNTs). Surprisingly, a combination of OMMT and Ni 2 O 3 led to high‐yield formation of MWNTs. X‐ray powder diffraction (XRD) and GC–MS were used to investigate the mechanism of this combination for the high‐yield formation of MWNTs from PP. Brønsted acid sites were created in degraded OMMT layers by thermal decomposition of the modifiers. The resultant carbenium ions play an important role in the carbonization of PP and the formation of MWNTs. The degradation of PP was induced by the presence of carbenium ions to form predominantly products with lower carbon numbers that could be easily catalyzed by the nickel catalyst for the growth of MWNTs. Furthermore, carbenium ions are active intermediates that promote the growth of MWNTs from the degradation products with higher carbon numbers through hydride‐transfer reactions. The XRD measurements showed that Ni 2 O 3 was reduced into metallic nickel (Ni) in situ to afford the active sites for the growth of MWNTs.