The mechanism behind ammonia reduction with oxygen and a platinum catalyst??

Question

I know the rxn
4NH3 + 5O2 -> 4NO + 6H2O

but does anyone have maybe a scanned img of the mechanism or a detailed explanation.

I started to say oxgen elections grab a pt2+ and then resonate to a + charge on the oxygen without the pt on it then the nitrogen free elections grab the positively charge oxygen and then oxygen electrons from another O2 grab off and H and the electrons go onto the N and stabalize it but from there im lost. thanks for the help

yes, I could have saved some lines and said oxidation of ammonia but it means the same thing as what I said in the description. I am doing a powerpoint presentation with this rxn and this will be more indepth rather than just showing "it is bc it is"

Answer 1

I suspect that platinum functions in this process the same way as it functions in an automotive catalytic converter. "The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NOx emissions. When an NO or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2. For example:

2NO => N2 + O2 or 2NO2 => N2 + 2O2"

My guess is that platinum is able to "rip" the nitrogen atoms out of the ammonia molecules, just as it does in the automobile's converter.

Answer 2

Your idea is on the right lines, but I don't think you'll find distinct Pt2+ in a metal, where all the electrons are pooled together.

Surface atoms in a metal are always more reactive because they don't have enough neighbours, so they can often chemically interact in ways that the bulk metal can't. Oxygen on the Pt surface splits into separate O atoms, chemically bound to surface Pt atoms. NH3 splits into surface-bound =NH and surface H atoms. Then the oxygen atoms move around and mop up the other bits to give your overall reaction. The surface-bound species can be detected spectroscopically.

This year's chemistry Nobel prize was given for sorting out reactions of this kind.