Simultaneous CO2 removal from biomass conversion product gas and carbon nanotube formation via catalytic chemical vapour deposition†
Catalytic chemical vapour deposition (CCVD) was evaluated as a multi-functional process to provide value-added products, syngas (CO + H2) and carbon nanotubes (CNTs), from a biomass gasification stream with the use of stainless steel and alumina supported catalysts. A deep investigation into the synthesis and characterisation of the catalysts was carried out as their intrinsic properties affect those of the produced CNTs, as well as the final composition of the gas downstream. Depending on the catalyst used, the H2/CO ratio was increased by a factor of up to 10 compared to the initial gas composition. This was accompanied by a large depletion of the initial CO2 levels with some of the catalysts. The quality of the multi-walled carbon nanotubes (MWCNTs) obtained without prior purification was analysed by scanning and transmission electron microscopy and Raman spectroscopy.