--- In biofuel@yahoogroups.com, Donald Allwright
<[EMAIL PROTECTED]> wrote:
> I am no chemist, so please correct me if I'm wrong.
> 
> Your suggestion would involve splitting the Carbon-Carbon bonds in the
> glycerol part of the molecule. This is certainly possible, as it's what
> happens with catalytic cracking. However if you're doing this to the
> glycerol part of the molecule you're probably also doing it to the
> Carbon-Carbon bonds in the fatty acid chains as well.

The picture is not so dark :)
Some catalysts (especialy organic ones - enzymes) are highly selective
in that they would break only some of the links but not the other. But
you are quite right, I too have a doubt for this direct conversion
step. The breakage of glycerol is much more probable.
There might even be some organisms which will ferment the glycerol for
you and make methanol, as Ken Provost correctly pointed out. Or
ethanol - this is much more probable, because methanol is very toxic
to living organisms ant ethanol is less toxic :).


so the fermenting bacteria or yeasts could do something like this:

2 CH2OH-CHOH-CH2OH + O2 ==> 2 CH3-CH2OH + 2 CO2 + 2 H2O

We can then feed the resulting ethanol back into our process.
Unfortunately ethanol will be hydrated, and will need some serious
distilation/dehydration.

The ethanol solution is a little less elegant than methanol. If you
achieve the later, then you do not need to supply the methanol to your
process at all. If you achieve the former, then you would only be
recycling 1/3 of the input of ethanol into the process. You get 3
methanol molecules if you break 1 glycerol molecule apart, but you get
only 1 ethanol for 1 glycerol (plus some carbon escapes in the form of
CO2).

so, has ANYONE here seen any mention on the web about such type of
yeast/bacteria? could be interesting....


> And in any case I doubt having a catalytic cracker in your kitchen,

Hmmm, IMHO, any biodiesel production process is not very suitable for
the kitchen. You could do a demo project in a kitchen, but if you try
to use biodiesel seriously, for your car, you will probably be scaling
up to a drum-sized batches. It's more likely a backyard or a garage
project. And once in backyard, there is much more freedom to toy with
chemistry :)


> plus a suitable supply of hydrogen
As I said, hydrogen need not be provided in gaseous form, it might be
some chemical. Like sodium borhydride

NaBH4 + H2O ==> NaBO2 + 4H2

This chemical is stable, and releases hydrogen only in the presence of
catalyst.

Of course you would then need to secure the source of the sodium
borhydride :). Good news is that borax, the final product of the above
reaction can be recycled back into borhydride with the coal reforming.
So in theory it could be recycled. Unfortunately this is far less user
friendly process, and it is better left to the industries (though not
insurmountable at home. Again, the catalyst is the key).


(be sure to check http://www.millenniumcell.com/solutions/index.html
for the interesting stuff about this chemical. These people are trying
to get fuel cell car on top of this chemical process)


So, lots of buts/ifs, but no showstoper problems in the overal design....






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