There are two major ways in which nanotechnology is being used to reduce air pollution: catalysts, which are currently in use and constantly being improved upon; and nano-structured membranes, which are under development.
Catalysts can be used to enable a chemical reaction (which changes one type of molecule to another) at lower temperatures or make the reaction more effective. Nanotechnology can improve the performance and cost of catalysts used to transform vapors escaping from cars or industrial plants into harmless gasses. That's because catalysts made from nanoparticles have a greater surface area to interact with the reacting chemicals than catalysts made from larger particles. The larger surface area allows more chemicals to interact with the catalyst simultaneously, which makes the catalyst more effective.
Nanostructured membranes, on the other hand, are being developed to separate carbon dioxide from industrial plant exhaust streams. The plan is to create a method that can be implemented in any power plant without expensive retrofitting.
See the following section for more about the potential of nanoparticle catalysts and nano-structured membranes in reducing air pollution.
Researchers at the University of Pittsburgh are using nanoporous materials called metal-organic frameworks (MOFs) to capture carbon dioxide from air or smoke stacks. In the MOF the carbon dioxide reacts with hydrogen to form formic acid, which can be used to produce products such as methanol.
Researchers at MIT have demonstrated a method to improve the conversion of carbon dioxide to useful chemicals with nanostructured catalysts by adjusting the flow to concentrate the carbon dioxide close to the surface of the catalyst.
Using gold nanoparticles embedded in a porous manganese oxide as a room temperature catalyst to breakdown volatile organic compounds in air.
Using crystals containing nano sized pores to trap carbon dioxide.
Using a nanocatalyst containing cobalt and platinum to remove nitrogen oxide from smokestacks
Reducing the amount of platinum used in catalytic converters.
Converting carbon dioxide to methanol; which can be used to power fuel-cells.
Reducing emissions from power plants by converting carbon dioxide into nanotubes.
Removal of carbon dioxide from industrial smoke stacks using carbon nanotube based membranes.