Controlling carbon monoxide emissions from automobile vehicle exhaust using copper oxide catalysts in a catalytic converter

Carbon monoxide (CO) is a very poisonous gas present in the atmosphere. It has significant effects on human beings, animals, plants and the climate. Automobile vehicle exhaust contributes 64% of the CO pollution in urban areas. To control this exhaust pollution, various types of catalysts in catalytic converters have been investigated. Increasing costs of noble metals as a catalyst in automobile vehicles motivates the investigation of material that can be substituted for noble metals. Among the non-noble metals, copper (Cu) is found to be the most capable and highly active catalyst for CO oxidation, compared to precious metal catalysts. Lower cost, easy availability and advance preparation conditions with stabilizers, promoters and so on, make Cu a good choice as an auto exhaust purification catalyst. The oxidation of CO proceeds very quickly over Cu°, followed by Cu+ and Cu2+. The Cu2O catalyst is more active in an O2-rich atmosphere than in O2-lean conditions. The reduced species of copper (Cu0, Cu+) are essential for better CO oxidation but smaller Cu particles could be less active than the higher ones. There is a great deal of research available on the Cu catalyst for CO oxidation, but there is a gap in the literature for a review article individually applied to the Cu catalyst for CO oxidation. To fill this gap, the present review updates information on Cu catalysts in the purification of exhaust gases. •The Cu2O also represents an active phase for CO oxidation when deposited on the catalyst surfaces.•The polycrystalline Cu films and open facets are more reactive to undertake the oxidation faster than the Cu(111) single crystals. The trend in efficiency for the oxidation of CO is Cu0 > Cu+ > Cu2+.•The increase of surface mobility is due to the released of Cu atoms from the redox cycle to which the CO can bind at room temperature and aid Cu diffusion.