Carbon vapor deposition (CVD) of carbon nanotubes (CNTs) has been modeled with a coupled gas-phase and surface chemistry model. The gas-phase flow model consisting of coupled conservation of mass, energy, and momentum equations was developed to describe the fluid flow of hydrocarbons and hydrogen as they undergo heating and chemical reactions in a horizontal tube-flow CVD reactor. The model outputs steady state velocity, temperature, and concentration fields for each species involved in the reaction mechanism. The fully coupled surface chemistry model, applied as a variable multidirectional flux boundary condition to the mass balance equation, determines steady-state surface coverage of each chemical species as well as the rate of growth of CNTs as a function of gas phase thermal and chemical conditions. The results of the modeling effort demonstrate a dependence on thermal conditions of optimal inlet molar ratios for efficient CNT production as well as the large effect specification of active sites can have on calculated deposition rates.

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