Multiwalled carbon nanotubes (MWCNT) are synthesized by isobutane decomposition at 700 degrees C over as-purchased and iron-loaded K10-montmorillonite catalysts. The results show that, upon reduction at 500 degrees C, K10 catalyzes isobutane decomposition. Few carbon fibers accompany the prevailing carbon flakes formation. Upon Na+ exchange or by increasing the reduction temperature, the activity of the clay decreases. Fe-K10 behaves as a bifunctional catalyst: on added metal sites, MWCNT preferentially form, while on the support, carbon flake formation mainly occurs. At a given metal load, the increase of the reduction temperature up to 700 degrees C or the use of Na+-exchanged K10 as a support generally leads to an enhancement of the selectivity to MWCNT, because of the diminishing of the support active sites. Under the present reaction conditions, Fe supported on Na+ exchanged K10 are the most active among the investigated catalysts. MWCNT copiously form, both at low and high metal load, and exhibit the highest structural order.

K10 Montmorillonite Based Catalysts for the Growth of Multiwalled Carbon Nanotubes through Catalytic Chemical Vapor Deposition

MILONE, Candida;GALVAGNO, Signorino;
2010

Abstract

Multiwalled carbon nanotubes (MWCNT) are synthesized by isobutane decomposition at 700 degrees C over as-purchased and iron-loaded K10-montmorillonite catalysts. The results show that, upon reduction at 500 degrees C, K10 catalyzes isobutane decomposition. Few carbon fibers accompany the prevailing carbon flakes formation. Upon Na+ exchange or by increasing the reduction temperature, the activity of the clay decreases. Fe-K10 behaves as a bifunctional catalyst: on added metal sites, MWCNT preferentially form, while on the support, carbon flake formation mainly occurs. At a given metal load, the increase of the reduction temperature up to 700 degrees C or the use of Na+-exchanged K10 as a support generally leads to an enhancement of the selectivity to MWCNT, because of the diminishing of the support active sites. Under the present reaction conditions, Fe supported on Na+ exchanged K10 are the most active among the investigated catalysts. MWCNT copiously form, both at low and high metal load, and exhibit the highest structural order.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11570/1901117
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