An Introduction to
Methanol Recovery...

For those trying to lower the production cost of biodiesel, methanol recovery is a common practice.

Excess methanol is used to push the transesterification process to completion. The excess methanol can be recovered from the glycerin by-product through the use of heat and a condenser.


How It Works:

• After the biodiesel has been produced, about 70% of the methanol left over will be found in the glycerin by-product. Boiling the methanol in a closed container and funneling it into a condenser can recover this portion.

• Recovered methanol can be used in the next batch of biodiesel but because it is not as pure as the original, a bit more will be needed and some extra catalyst as well.

• Approximately 30% of the remnant methanol is in the un-washed biodiesel. It's my opinion that it takes too much energy and time to be worth reclaiming this portion. Just wash the biodiesel and dispose of the waste.


Tips:

• Methanol boils at 148.5°F (64.7°C).

• Do not heat heat the glycerin mixture in an aluminum pot as the methanol will corrode it!

• The methanol should be removed only after the glycerin has been separated off, otherwise it could cause a reverse reaction – returning your biodiesel to *gasp* GLYCERIDES!

• If you intend to separate the glycerin into its different components, that should be done before the methanol is removed. (Some reactions rely on the methanol in order to take place.)

• Methanol Recovery results in a biodiesel by-product. See what you can do with other biodiesel waste products.


Recover It!

You can build your own reflux still by following the instructions on this website: http://www.moonshine-still.com/


Test the Purity of the Methanol:

Methanol needs to have a purity of 95% or greater to avoid problems caused by having too much water in the batch.

To determine the purity of recovered methanol, use a hydrometer (about $25 USD) to measure the specific gravity. 200 proof is pure methanol, 0 proof is pure water... so 100 proof would be half and half. I'm sure you can calculate the rest :)

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