(316a) Single-Step Synthesis of Aligned High Aspect Ratio Mwcnts Impregnated with Al2O3 Particles in an Ultrasonic Atomization Head CVD Reactor

Commercializing the production of functionalized CNTs with distinguish surface properties for nano applications is highly dependent on the development of synthesis and functionalization methods that can be easily implemented and scaled up. Conventional metal oxide CNT impregnation methods involve various steps that are time consuming and difficult to control. In this study, an injection vertical CVD reactor fitted with an ultrasonic atomization head is used in a pilot-plant scale reactor for semi continuous production of MWCNTs in-situ impregnated with Al₂O₃ particles. Ferrocene as a source of iron catalyst and aluminum isopropoxide as a source of aluminum oxide nanoparticles are dissolved in p-xylene to make a homogeneous feed solution to the reactor. The Atomization of the feed solution resulted in full and even dispersion of the catalytic solution, which controlled the diameters of the produced MWCNTs. The reactor produced High quality and high aspect ratio bundles, aligned, MWCNTs decorated with Al₂O₃ particles as confirmed by TEM and EDS characterization. TEM images reveled that alumina particles only decorated the outer surface of the tubes and were not present inside the tubes as the hollow structure of the tubes were visible. The use of the support free ferrocene catalyst insured the fully exposer of the metal particles to the hydrocarbon source which resulted in high production yields at optimized conditions. The effect of different reaction parameters on production yields and properties of the produced CNTs were investigated. High yields of pure high surface area MWCNTs were achieved at an optimum temperature of 800 ^oC as confirmed by SEM images and TGA analysis. The effect of temperature is thought to be due to major alterations in the distribution of atoms at the metal/gas interface. The presented reactor system can be easily controlled to produce MWCNTs impregnated with metal oxides with a wide range of surface properties compared to conventional fluidized bed reactors that are relatively difficult to control.