Abstract—A study on the optimization of the process parameters and catalyst metal loading was done for the production of CNTs over Ni-Cu/Al2O3 in a fluidized bed reactor. The process parameters investigated were the inlet CH4 concentration and the reaction temperature. Optimization was done in terms of minimizing the diameter of the CNTs formed through the latest Solver function of Excel with integer and binary constraints on respective variables. The determination of the significance of the process and catalyst parameters was through ANOVA, and the behaviour of the response variable as a function of the set parameters was qualified through contour, main effect and interaction plots. Catalyst pre-characterization confirmed the presence of γ-Al2O3, NiO and NiCu catalyst components which are necessary in the production of CNTs. Catalyst post-characterization allowed the identification of CNTs and the measurement of their diameters. The smallest average CNT diameter was 48.5 nm produced with 5% CH4, 30% Ni loading with 12:5 mol: mol Ni: Cu under a 950°C reaction temperature. The initial surface area of the catalyst had no significant effect on the diameter of the CNTs formed. The non-linear model developed illustrated that the CNT diameter was generally inversely proportional with and a strong function of reaction temperature, while it is a weaker function of CH4 concentration and catalyst metal loading. The model had a PCC of 0.944 and a PCC P-value of 0.000. A minimum CNT diameter of 47.75 nm with the parameters set at 5% CH4, 10% Ni loading with 12:5 mol: mol Ni: Cu, and 950°C reaction temperature was subsequently predicted by minimizing the model.
Index Terms—Carbon nanotubes, catalysis, methanedecomposition, hydrogen storage, CNT diameter model
Gian Paolo Obligacion Bernardo is with the De La Salle University –Manila (e-mail: gpobernardo@yahoo.com).
Leonila C. Abella is with the Chemical Engineering, College of Engineering, De La Salle University - Manila
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Cite: Gian Paolo Obligacion Bernardo and Leonila C. Abella, "CNT Production through the Catalytic Thermal Decomposition of Methane over Ni-Cu/Al2O3 Catalyst in a Fluidized Bed," International Journal of Chemical Engineering and Applications vol. 3, no. 6, pp. 446-449, 2012.
