[kateman]

Something made me think today, are there any catalysts for combustion?

I know it depends on the fule (such as hydrocarbons) but I wanted to leave this open to any kind of fule - I was just interested if there are catalysts for combustion and if so, what fule and what are the catalysts???

Thanks 

 

[P]

Oxygen?  Or oxidisers such as potassium Permanganate will give off oxygen and enhance a fire.

[kateman]

thanks for your reply but no, i meant a catalyst as in a substance that speeds up the reaction but doesnt become used up during the reaction, not an oxidiser

it may seem pointless and unexplored but thats why it interests me

see this link, these sellers claim to have such a thing but arn't saying exactly what it is they are using:

http://www.alibaba.com/product-free/12154467/Combustion_Catalyst_System.html

 http://www.atechtt.com/cv100.htm

http://www.ftek.com/combustionCatalysts.php

the latter probably gives the most clues away but doesn't really help

any ideas?

[Arkcon]

Internal combustion engines are closed, metered systems.  That is, fixed amount of fuel, atomized (I mean sprayed, not split into atoms,) mixed with a metered amount of air, etc.  This is different than say, fuel in a open cup, and many things are added to automotive fuel to enhance a number of qualities.  The term "catalyst" applied here is just an industry buzzword.  There are too many variables in auto fuel needs for a reasonable, non-biased, chemistry-based reply.  But generally, if it smells like b******t, then it is.  Or if the chemist sounds like a cartoon used car salesman, or a TV evangelist -- you just smile and back away slowly.

[Borek]

Oxygen?  Or oxidisers such as potassium Permanganate will give off oxygen and enhance a fire.

Oxygen is one of the reactants, I would not clasify it as a catalyst.

Eons ago I have read that cigarette ash catalyzes burning of sucrose, but I was never able to do it by myself. I know someone claiming that was his best party trick, perhaps one day I will meet him somewhere where there will be enough cigarettes and sugar to try

[kateman]

interesting about the sucrose Borek

do any of you think this would be an unexplored area of chemistry or that there is just no such thing as a combustion catalyst?

how are catalysts normally found for certain reactions?
Do they just throw whatever into the mixture and hope for the best or do they identify what bonding occurs and how the molecules interact and put a substance with similar properties in the reaction?

This has got me intrigued 

[Arkcon]

A while back, on another forum, the cigarette ash as catalyst story came up.  I'd read that story too -- that a cube of sugar will not ignite in a match flame, you need cigarette ash as a catalyst.  But later I'd heard that a sugar cube can be easily lit, just hold it in an ignition source, and it starts to burn.  Having burnt sugar that spilled into a stove gas flame, I'd have to agree with the latter story. 

But then, what is the first story coming from?  Is it just an example for kids of what a catalyst is?  If so, it's a pretty crappy one, if it ends up false later.  Or is it functioning like a candle wick?  If so, is it fair to discount it as a catalyst -- it's harder to ignite the side of a candle too, but the wick lets you burn the whole thing down.  That is the definition of a catalyst -- makes a reaction, that is already thermodynamically likely, happen faster.

And what is in the cigarette ash?  It should be just trace minerals that don't burn.  For example, platinum is a common hydrogenation catalyst.  This is because hydrogen has a high affinity for the platinum surface, and even though we describe platinum as "non-reactive", a short lived, pseudo-compound forms, that later reacts with something with a stronger affinity for hydrogen.  The platinum functioning as like a "catcher" or "getter" for hydrogen.  Can you really call a physical wick the same thing?  These are the topics of discussion that were brought up back then.

[enahs]

Back in the day, yes the development of catalysts was just trial and error. But you would look at how other catalysts were successful (i.e in nature or other developed processes) and what type of reactions it catalyzed, and try it on what you want. And with a little more science, that is still done today. But there is also a field of more "science" with calculations and such developing very well with regards to catalysts.

A catalysts works by lowering the activation energy of chemical reaction.
Fuel combustion is already have fairly low activation energies. If you lower them too much, they are not stable for storage, or react to readily and will not be in as a controlled manner (something very important for getting useful energy out of it).

I am not saying it will not work, and not improve things. But catalysts are not usually developed for reactions that are already highly spontaneous, both kinetically and thermodynamically.

[Arkcon]

If you really want the bitter discussion of the cigarette ash as wick not catalyst, I've added a link to an old sci.chem discussion.  It's not the same one I recall, but it is, in fact, better, because the original poster tries a variety of materials, confirms it is a wick, and ends up, just like me, disappointed at the triviality of the physical result, as opposed to a chemical one.  Note that sci.chem on the Usenet wasn't always a friendly place, and be ready for arrogant responses.  That said,:

http://groups.google.com/group/sci.chem/browse_thread/thread/9b04ce5029868223/7392ef6f8b4adb7f?lnk=gst&q=ash+catalyst#7392ef6f8b4adb7f

[kateman]

Thank you Enahs and Arkcon

I know it seems pointless but it intrigues me