Scientists have developed a new catalyst for the oxidation of carbon monoxide; this catalyst could help reducing the emission of this gas in the environment, and hence reducing atmosphere pollution.
The new catalyst is based on nanocrystals of either platinum, palladium or nickel, deposited on cerium oxide; the support, in particular, seems to play a major role in the oxidation reaction.
Carbone monoxide (CO) is a gaseous molecule. Although this gas has some important industrial applications, its presence in the atmosphere is a cause for concern, as it can be lethal for humans.
CO is generally formed from incomplete combustion of carbon-containing fuels (i.e. methane, gasoline, etc.); this happens if the combustion is performed without enough oxygen (O2). Considering the case of methane, for instance, we have:
CH4 + 2 O2 → CO2 + 2 H2O = complete combustion
CH4 + 1.5 O2 → CO + 2 H2O = incomplete combustion
CO: Dangerous Gas
CO is dangerous for humans, as it bonds to the iron of the hemoglobin present in the blood. In this way, the iron-hemoglobin complex cannot react with the oxygen; this means that the blood does not get oxygenated, which can lead to death.
A typical situation in which CO can form is with old gas heaters, in a closed environment (i.e. a room with all doors and windows closed). In this case, CO could be lethal for the people present in the room.
Other cases can be car engines or a power station, if the combustion system is not very efficient. The CO formed would be released into the atmosphere, thus increasing the level of pollution.
Oxidizing Carbon Monoxide
To avoid the release of carbon monoxide into the atmosphere, CO is normally converted into carbon dioxide (CO2). Although carbon dioxide is a greenhouse gas, which some people think responsible for global warming, CO2 is not hazardous for human health.
This oxidation reaction takes place according to the equation:
CO + ½ O2 → CO2
This process is performed, for instance, in catalytic converters.
For the reaction to happen, a catalyst is required; the choice of an appropriate catalyst is essential, for the reaction to be complete and for the CO not to be emitted in the atmosphere. The most used catalysts are based on precious metals such as platinum, palladium or rhodium.
CO Oxidation: New Catalyst
Researchers have performed several studies over the years to improve the formulation of the catalyst, and hence increase its efficiency. Professor Paolo Fornasiero, from the University of Trieste, the ICCOM-CNR Institute and the National Consortium INSTM(Italy) achieved important results in this field, in work that was performed in cooperation with the University of Pennsylvania (US) and the Brookhaven National Laboratories (Upton, US). The results were published in Science Express on the 18th of July 2013.
The catalyst developed by Professor Fornasiero and his coworkers is based on a ceramic support, covered with nanocrystals of metals such as platinum (Pt), palladium (Pd) or nickel (Ni).
Decoding Science. One article at a time.