CO oxidation and the inhibition effects of carboxyl-modification and copper clusters on multi-walled carbon nanotubes

An inhibition of CO oxidation on catalytically active pristine multi-walled carbon nanotubes (MWCNT) in the presence of selected pollutant constituents in flue gas streams was studied. We simulated an interaction between the active MWCNT and the contaminants in CO oxidation atmosphere of: (i) an acidic wet flue gas environment modelled by using MWCNT grafted with carboxyl (-COOH) groups; and (ii) a polluted environment formed by trace metal copper particles and other contaminant constituents (e.g. PAHs, VOCs and P) by using a copper cluster of chemical formulae [(PPh3)CuH](6)center dot 0.75THF as a model pollutant, doped on the MWCNT. The pristine, unmodified MWCNT were catalytically active from similar to 150 degrees C, whilst the carboxyl-modified MWCNT behaved as an adsorbent of CO molecules without converting them into CO2. The copper cluster was found to have formed CuCO3 during the CO oxidation reaction at temperatures below 330 degrees C but decomposed above 400 degrees C to release CO2 product.