Carbon nanotube columns for flow systems: influence of synthesis parameters

Flow reactors are expected to play an increasingly important role in the production of chemicals. A simple carbon-based scaffold to easily develop flow systems is here detailed. Using a chemical vapour deposition technique, the controlled in situ growth of vertically aligned (VA) multi-wall carbon nanotubes (MWCNTs) into quartz columns with 2 mm inner diameter is achieved. Several of the described MWCNT columns (CNCs) can be produced at a time. The influence of synthesis parameters on the formation of these VA-MWCNT scaffolds is reported and discussed (e.g. injection time of the precursor, carrier gas flow rate, inner diameter and length of the quartz column, position in the furnace during synthesis). Raman spectroscopy, optical microscopy, scanning and transmission electron microscopy are used to assess the coverage of the inner channel of the quartz column with VA-MWCNTs and their overall quality. The length of the CNCs together with the carrier gas flow rate are found to be key parameters to control the MWCNT length profile within the CNCs. Fluoresceinamine molecules and platinum nanoparticles are successfully immobilised within these MWCNT scaffolds. The benefits of the CNCs for flow system design are summarised as the controlled filling with MWCNTs makes the detailed CNCs versatile scaffolds for flow catalysis and filtration.