Optimization of CVD growth of CNT-based hybrids using the Taguchi method

Taguchi method, extensively applied for the optimization of multifactor processes in the most diverse fields, is for the first time applied to the synthesis of hybrids based on C nanotubes by iron-catalyzed chemical vapor deposition in 1:1 i-C4H10 + H2 atmosphere. For this purpose, assumed synthesis-temperature (500 °C, 600 °C or 700 °C), support-material (alumina, magnesia or Na+-exchanged K10 montmorillonite), calcination (450 °C, 600 °C or 750 °C) and reduction (500 °C, 600 °C or 700 °C) temperature of the iron catalysts as the four factors of importance in the process, nine suitably designed experiments are conducted and the influence is evaluated of the four three-level factors on the issue of the process in terms of selectivity toward nanotubes, catalytic yield and content of carbonaceous and metallic impurities in the C nanotubes. By this procedure, the configurations giving optimal results are predicted, and tested by carrying out new experiments.

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► Taguchi method is applied to optimize the synthesis of hybrids based on CNTs.
► Synthesis-temperature mostly influences yield and selectivity of the CVD process.
► Catalyst support-material chiefly controls iron-encapsulation by carbon.
► Catalyst reduction-temperature greatly influences amorphous carbon formation.
► After optimization catalytic yield increases from 130 wt% to 760 wt%.