Carbon nanotubes based catalysts

Case - Use of Carbon Nanotube-Based Catalysts in Hydrogen Production... 

The type of carbon formed depends on the reaction conditions, whereby higher reaction temperatures favour the formation of the more inert-graphitic carbon nanotubes. Based on kinetic and isotopic investigations on the mechanism of DRM reaction over Ni/MgO catalysts, Wei and Iglesia [189] observed a similarity in turnover rates and first-order rate constants with methane decomposition. Hence, they concluded that the dissociation is the kinetically relevant step for the DRM reaction and that the Ni behavior resembles that of supported noble metal catalysts (Rh, Pt, Ir, Ru). 

Cao R, Thapa R, Kim H, Xu X, Kim M-G, Li Q, Park N, Liu M, Cho J (2013) Promotion of oxygen reduction by a bio-inspired tethered iron phthalocyanine carbon nanotube-based catalyst Nature Comm 4 2076... 

The development of new porous materials that could be used as adsorbents, catalysts, catalyst supports, molecular sieves, etc. [1], are very well discussed by several authors [2-9], describing interesting properties and characteristics of materials such as MCM-41, MCM-48, M41S, FSM16, lamellar phases, intercalation products, special CMS (carbon molecular sieves), fullerenes, carbon nanotubes, etc. being some of them silica based materials, and carbon based the others. 

Lopez P.N., Ramos I.R., Ruiz A.G. A study of carbon nanotube formation by C2H2 decomposition on an iron based catalyst using a pulsed method. Carbon, 2003,41(13), 2509-2517. 

A series of supported chiral VO(salen) complexes anchored on silica, single-wall carbon nanotube, achvated carbon or ionic liquids have been prepared through the simple methods based on the addition of mercapto groups to terminal C=C double bonds (Scheme 7.17) [58]. The four recoverable catalysts and the standard VO(salen) complex 37 were tested for the enantioselechve cyanosilylation of benzaldehyde using trimethylsilyl cyanide (Table 7.9). It should be noted that the ionic liquid-supported IL-VO(salen) showed the highest catalyhc achvity, though the ee-value was considerably reduced compared to the soluble 37 in [bmim][PF6] (entries 4 and 5). 

At the beginning of the 2U century, it is thought that the improvement of the existing chemical industry will pass through the development of new kinds of catalysts to meet the latest environmental requirements. Since their discovery in 1991 [1], carbon nanotubes and nanofibers have received increasing interest in academic research and for several potential applications [2-4]. It has been reported by different authors that carbon nanofibers could be efficiently used as catalyst support for several catalytic reactions either in gas or in liquid phase [5-7], In both cases, the carbon nanofiber based catalysts always exhibited higher catalytic performances compared to those observed on equivalent conventional catalysts. 

The nickel based catalyst was prepared by immersion of the carbon nanotube support (under stiring) in a small excess of an aqueous solution of nickel nitrate (Ni(N03)2.6H20, Merck) relatively to the pore volume of the material. The tubes were then impregnated with a volume of benzene corresponding to the tubule internal volume. Due to the high affinity of the benzene with the carbon nanotube the aqueous solution containing nickel salt was immediately pushed outside the tubules. 

---