Body
 |
|
 |
| AN SPIDER WEB AT MY WINDOW | ||
LIONEL CERVERA GONTARD |
||
| Negative of an SEM image of a TEM Cu grid with holey C film acquired at 20 kV with the secondary electron detector. The powder on the film is carbon black impregnated with Pt nanoparticles, and which is an heterogenous catalyst that can be found inside car exhausters. This catalyst reduces NOx emissions. When a NO or NO2 molecule contacts the surface of a nanoparticle, the catalyst removes the nitrogen atom from the molecule and retains it, freeing the oxygen that remains adsorbed. The retained nitrogen atoms then bond with other nitrogen atoms that have also adhered to the catalyst, to form N2. The reactions can be summarised by the relations: 2NO -> N2 + O2 or 2NO2 -> N2 + 2O2. In a second stage reduces unburned hydrocarbons and carbon monoxide by burning (oxidizing) with the remaining oxygen adsorbed on the platinum surface or present in the exhaust gas. 2CO + O2 -> 2CO2. | ||
 |
