lehpron
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Separating Chemicals From Another?

Wed Oct 06, 2004 9:26 am

Can this be done, or has it been done:

A machine that can create/strain methane or hydrogen out of some/any standard hydrocarbon fuel(s). what needs to go in/out to make this happen?






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N6376M
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RE: Separating Chemicals From Another?

Wed Oct 06, 2004 9:51 am

Isn't this called a fractional distillation tower? As long as the boiling points are different you can do it.
 
aloges
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RE: Separating Chemicals From Another?

Wed Oct 06, 2004 9:57 am

To get the hydrogen, just burn the fuel you have, collect the water vapour contained in the exhaust gases and separate Hydrogen from Oxygen electrically. Use the heat of the fire to generate the electricity needed if you care about efficiency.  Laugh out loud

Methane? Some nasty cracking would be needed for that one, and you'd get a load of residuals such as sulphur compounds. Not exactly an easy way to produce Methane.
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CaptOveur
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RE: Separating Chemicals From Another?

Wed Oct 06, 2004 10:07 am

It is simple.. just heat the source material and find the temp in the tower where the product you want condenses.. put your collection source there.. probably not something to do in your basement but it can be done.
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MD11Engineer
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RE: Separating Chemicals From Another?

Wed Oct 06, 2004 1:09 pm

If you have liquid hydrocarbons, this usually means long chains of -C-c-c-c-, you can split them up in smaller parts using a process called "cracking".
The simplest way is to expose the hydrocarbon to great heat, this will cause C-C bonds to break up, afterwards you distill and seperate the new molecules. Other cracking processes use catalysts like Al2O3 and lower heat (better control). Methane is the simplest hydrocarbon CH4.

There are also processes for dehydrogenation of hydrocarbons, usually they are used to create hydrocarbons with double bonds -C=C- or triple bonds, these hydrocarbons are very reactive and form the base of many plastics.

Just get yourself a textbook on basic organic chemistry.

Jan
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Logan22L
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RE: Separating Chemicals From Another?

Wed Oct 06, 2004 10:37 pm

Cracking can be done to produce methane; however, it is typically cheaper to perform hydraulic fracturing, where a fluid and sand is injected at high pressure into coal beds. The sand helps to prop open the natural fractures in the formation, and extraction wells recover naturally-occurring methane from the coal beds. Incidentally, Halliburton (of Dick Cheney fame) is a big player in this field.

Most standard hydrocarbon fuel (i.e., crude oil) is low in methane simply because of its gaseous nature, so the methane is lost relatively easily from the crude. As for hydrogen, it can be generated electrolytically from water, but not really from hydrocarbons. Not the easiest (or cheapest) thing to do, and not very safe on a large scale.

Logan
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FDXmech
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RE: Separating Chemicals From Another?

Thu Oct 07, 2004 12:41 am

It's actually simple, until you combine them.

If their not combined, simply push the jars further apart.
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lehpron
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RE: Separating Chemicals From Another?

Fri Oct 08, 2004 4:39 am

fractional distillation tower? I will look that up for sure thanks, and chemical uses for the word 'cracking'. I worry if i search for cracking and methane in google I'll end with meth-lab-how-to's.  Nuts

Aren't the flash points and boiling points for hydrocarbons close to each other, how are they kept from going off when doing this procedure of cracking?

Specifically, I was wondering about those ideas about hypersonic/suborbital airliners in our distant future...instead of hauling the cryogenic fuel to the airport, why not make it from standard JetA/B by placing one of these "cracking towers" at the airport facility? Wouldn't it be way cheaper?
The meaning of life is curiosity; we were put on this planet to explore opportunities.
 
mdsh00
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RE: Separating Chemicals From Another?

Fri Oct 08, 2004 4:47 am

I think everyone got it right over here. You can separate by fractionation, polarity and organic vs. inorganic. Just remember that like dissolves in like.
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Logan22L
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RE: Separating Chemicals From Another?

Fri Oct 08, 2004 4:58 am

Lehpron: I don't think that cracking is the best way to go here. While it will break down larger hydrocarbons, getting the process to go all the way to methane (and not hundreds of other side products) may not be feasible. The time and expense to do this is probably prohibitive. Why not just use the fuel you already have? I don't see the advantage to breaking it down. If you are looking at this from a cleaner burning perspective, then the cracked fuel would still have all the impurities that cause inefficiencies in combustion with Jet A. While they could be removed, this would be a difficult task at the airport itself. I don't think we want to have an active refinery alongside our runways. Given the expense of crude and the cracking/purification process, I think we're talking expensive here.

Your interest in alternatives to the norm is good - one thing about this is that at least the petroleum industry would be involved still, and that's about the only way alternatives can get developed. Talk of hydrogen, etc. just doesn't have the lobbying power. Maybe more research into zeolites (the catalysts used in cracking) would help move this idea along. I am trained as a chemist, but cracking isn't my area of expertise. Maybe some other member has more experience.

Logan

"The deeper you go, the higher you fly. The higher you fly, the deeper you go."
 
lehpron
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RE: Separating Chemicals From Another?

Fri Oct 08, 2004 6:59 am

>> "Why not just use the fuel you already have?

Actually I have read that standard jet fuels like Jet A prematurely break down and decay when burned at higher temps which is usually associated with hypersonic combustion chambers -- that was why I asked.

It is just that liquid methane or hydrogen cannot be hauled like jet fuel, so I was thinking of making them at the airport facility, it would cut down costs of transportation and long term storage and safety. In this case it would be a temporary storage as direct input into the plane's refrigeration system.

Besides environment, it is really an efficiency issue. I was wondering if it would be chemically practical to build these machines at airports that would service future hypersonic airliners.


Of course, if this machine were placed inside the airplane as a fuel converter, then yes we may be able to use regular fuel, just there may be stuff dumped during the process...I assume cracking fuel will give off by-products?
The meaning of life is curiosity; we were put on this planet to explore opportunities.
 
JetService
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RE: Separating Chemicals From Another?

Fri Oct 08, 2004 7:55 am

It's actually simple, until you combine them.

If their not combined, simply push the jars further apart.


LOL!!!

Then order the #2 at Taco Bell to get your methane.
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oly720man
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RE: Separating Chemicals From Another?

Fri Oct 08, 2004 8:43 am

Methane at airports....? Lots of cows to eat the grass. They produce loads of the stuff.

Seriously though, I'd guess that the energy involved in breaking down the long chain HCs into methane would not make the process cost effective. Using bacteria might work, though not necessarily in the desired volumes.
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lehpron
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RE: Separating Chemicals From Another?

Sat Oct 09, 2004 3:21 pm

What aspect of this process would make it costly? Size, output volume, rate of previous, the fact that there might not be this many number of units, etc.

Gimme an idea.
The meaning of life is curiosity; we were put on this planet to explore opportunities.
 
Southamerica
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RE: Separating Chemicals From Another?

Sun Oct 10, 2004 2:30 am


Not to mention time, which can also be a huge issue. While the vast majority of inorganic/mineral reactions take no more than a few seconds to happen, almost all organic proceedures take a lot of time and patience, unless an accelerator (which can be sometimes very expesive) is used.

A lot of energy, as Oly720man said, is to be used. While the C=C type of ties are relatively easy to brake, the C-C groups, representative of saturated hydrocarbons, are extremely stable and hard to break. That's why saturated or simple hydrocarbons do not tend to participate much in chemical reactions, while other type of hydrocarbons (insaturated ones) do.


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