Biopowered - vegetable oil and biodiesel forum
Biodiesel => Chemistry and process => Topic started by: julianf on June 21, 2013, 09:36:27 AM
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One of the side reactions (unwanted) that we have going on is the -
Acid + Base >> Salt + Water
reaction. Its often called a "neutralisation" reaction.
Its why FFAs (free fatty acids) are the problem - not only do they take out the base (which would only be a catalyst in our main transesterification reaction - ie not used / taken out), but also the reaction itself creates water, which further goes on to mess things up in the second unwanted reaction - the saponification reaction (the one that makes soap)
I just had an idea - i have not thought about it that much, but here goes -
Hot oil can be dried by bulbing / spray bars etc.
Once the methoxide is added, this is when the neutralisation reaction would normally occur - but the oil cant be dried with air then, as the methanol would be lost.
What about separating the neutralisation reaction?
Say, for example, having a setup where the oil is heated, bubbled / sprayed or whatever, but, once hot and dry, a recirculating system can be added, where the oil is pumped through a canister of captive base?
This may not work in the slightest - ive never tried it. The base may react with hot neutral oil. Or the water liberated in the neutralisation may just saponify furiously (likly, i think) and create "a right mess".
...but maybe it may be possible with a much milder base than what we usually use?
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The catalyst-in-a-can approach was mentioned once a while back on VOD but like you say the concern is not just dissolving it into the oil/methanol/water mix. Empty tin then :)
I guess you could dip it into the hot oil/methanol in a big catalyst tea bag. More bio vicar?
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Might be worth trying out with summit like Sodium Bicarbonate powder....
--That wont saponify the oil as far as I know, although if it works, will probably liberate moisture, into which the bicarb would dissolve and probably end up with a sludgy crud at the bottom if settled off...
Anyone got some high-tit to try it out with....?