Friday, December 15, 2006

Purifying Bio-Diesel After Transesterification

Given the current and projected world-wide energy demands, I have been seeing more literature, newsletter, and journal references to biomass derived energy sources to reduce demand for petroleum-based fuels and be better for the environment. One area of development is the production of biodiesel, but it has a serious downside. As a major ion exchange supplier, we are seeing substantial developments in the purification of biodiesel using specialized ion exchange resins.

Chemical Process:
The process to manufacture biodiesel requires transesterification of a vegetable based oil in the presence of a catalyst and methanol. What results are raw biodiesel (methyl ester), soap, catalyst, glycerol, and methanol. This raw biodiesel needs to be purified to applicable standards, EN14214 or ASTM D6751.

The typical purification process uses as many as 8 successive water washings of the raw biodiesel. This transfers water soluble impurities soap, catalyst, glycerol, methanol, and some biodiesel to the water. This results in a huge amount of organic and catalyst contaminated wastewater. So for every gallon of biodiesel produced, you end up with 8 gallons of liquid waste. Not a very environmentally friendly byproduct of biodiesel production.

A very elegant solution is available and being used extensively in Europe, a leader in biodiesel production. The raw biodiesel or once washed raw biodiesel is flowed through a tank of a special ion exchange resin. The resin readily removes the glycerol, soap, and catalyst, all corrosive to diesel engine components, and water from the raw biodiesel. It can take the glycerin from 500 ppm down to less than 10 ppm. This is significantly below the standard of 200 ppm. This potentially allows for higher concentration of biodiesel in blends with petroleum diesel.

From literature and papers published by several ion exchange manufacturers, depending upon the process, 1 lb of ion exchange resin can treat 900 - 2000 lbs of biodiesel. Work is being done to have a way to regenerate the resin to allow for reuse.


Anonymous said...

It is very nice to see about subject you have chosen, it is surprising for me that I am also making 'informational research' on the same subject you indicated,i.e. purification of bio diesel by ion exchange.
I would like to give you some information that "LEWATIT K 2567" RESIN is useful in purification of biodiesel.
I think we should live in touch to share more information, this will beneficial to both.
with warm regards..

T Dupnik said...

M. Parmar:
Yes, I would be interested in discussing your experience with the LANXESS LEWATIT K 2567 product. I tried to find the product bulletin on site without success. All I found was a press release. What I was hoping to find was whether they use any water washings before ion exchange purification or do they simply purify the raw biodiesel.

I know that Purolite has their PD 206. They have in their literature using one water washing of the raw biodiesel. Rohm and Haas, another ion exchange resin manufacturer with a biodiesel purification product, treats the raw biodiesel. The R&H product is called Amberlite BD10DRY.

Anonymous said...

can you please help me by answering how exactly an ion exchange for biodiesel works, including material balance and intial and final products? please, i need it dor my plant design which includes this process. thanks!

T Dupnik said...

Ion exchange resins can be used to purify biodiesel. A major resin supplier, Purolite, has an excellent applications bulletin for their product is called Purolite(R) PD 206. They have in their literature using the PD 206 ion exchange resin after one water washing of the raw biodiesel. This may help you size your biodiesel plant.

Purolite Biodiesel Applications Bulletin
Purolite PD 206 Biodiesel FAQ Bulletin
Purolite PD 206 Biodiesel Product Bulletin

Magical said...

Hi all,

I know that Lanxess is having a product call Lewatit GF 202 for Biodiesel purification. This is a great product and the best part is there is no water involved plus this product. U can check up more from

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Anonymous said...

I wanted to say that it’s nice to know that someone else also mentioned this as I had trouble finding the same info elsewhere. This was the first place that told me the answer. Thanks.

Anonymous said...

Pretty insightful post. Never thought that it was this simple after all. I had spent a good deal of my time looking for someone to explain this subject clearly and you’re the only one that ever did that. Kudos to you! Keep it up

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