Is reducing nitrogen oxides with ammonia practical in a gasifier? [closed]








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Sorry if this is an outright stupid question. I am no chemist.


For nitric oxide:


$$
\ce{2NH3 + 2NO -> 2 N2 + H2 + 2H2O}
$$


For nitrogen dioxide:


$$
\ce{2NH3 + 2NO2 -> 2N2 + H2 + 2H2O + O2}
$$


or


$$
\ce{4NH3 + 2NO2 -> 3N2 + 2H2 + 4H2O}
$$


As you can see, I'm trying to find if it is practical to take two toxins and convert them into non-volatile substances. Also, of course, harvesting this hydrogen gas would also be preferred; you could just add it back into the resulting Syngas. And I suppose ammonia doesn't have to be used. It just seemed convenient and the above reactions (producing useful Hydrogen and other non-volatiles) somehow came into my mind.


And it seems for every $\ce{O}$ (or $\ce{N}$) in the $\ce{NO\_{x}}$ it can make another $\ce{O2}$ (or $\ce{N2}$, respectively). Or double the ammonia, to effectively double up on the first reaction.


If its the case that one reaction is more practical than another (as it usually is). I have noticed that conversion is simple: 


$$
\ce{2NO + O2 -> 2NO2}
$$


readily happens in air and at 150C it reverses:


$$
\ce{2NO2 -> 2NO + O2}
$$


Most of this leads to gasification. Gasifiers stratify the combustion process to extract producer gas (Called Syngas. It is $\ce{H2 + CO}$, and it burns clean.). If a gasifier is built a certain way, the only pollutants could be $\ce{NO\_{x}}$, and since some gasifiers can use biowaste, then ammonia is not hard to reconstitute on-site in some applications. Plus, I think it might be possible to extract ammonia directly from the pyrolysis stage when using garbage in certain gasifiers. As well, I think Ammonia is in the resulting trace gases sometimes depending on the gasifier/fuel setup.


There are some resources to be had. Gasifiers also have to typically filter out sulfur and mercury from the resulting Syngas. If those can help at all here and/or could also be included in this detoxification. As well, there are usually sources of heat (up to 1100C), tar, char (hot carbon), and hot or cold ash (burnt charcoal), $\ce{H2 + CO}$, $\ce{CO2}$, and other trace gases like $\ce{CH4}$ or whatever, depending on the gasifier and fuel. These resources could be utilized if needed, but most already have a role to play. Carbon dioxide, methane and tar are used to make more Syngas. The wasted byproducts are: sulfur, mercury, cold ash, and the "whatever" trace gases. I believe sulfur is in the form hydrogen sulfide. There is also probably substantial unsued hot Char (hot reactive carbon), but it burns quick, and only exists in the heart of the machine, then once all the heat is extracted it turns to ash.


Actually, I wonder if I could pump the $\ce{NO\_{x}}$ (or other pollutants) back into the pyrolysis stage, if they would might reform into something else. Less toxic, eventually.


Of course, I feel like I'm barking up the wrong tree. As $\ce{NO\_{x}}$ gases are closely scrutinized by municipalities, any practical reduction would probably be used already and emission of $\ce{NO\_{x}}$ gases into the environment wouldn't be a problem, but that is assuming way too much for humans. So, I have to ask:


**Do any chemists see a way, using these resources (or other practical external ones), to detoxify the nitrogen oxide from the resulting burnt Syngas fumes?**


