How butanol is made
We have covered a few times the potential of biobutanol as a biofuel: It seems to have better properties than ethanol and it can be used in cars without modifications. It also has almost the same energy content as gasoline, thus reducing fuel consumption in comparison to ethanol.
In a deep article about the use of butanol for ICE (internal combustion engines) published by Consumer, a magazine created by a chain of Spanish supermarkets, there is an interesting section about the origin of butanol.
Before World War I, several scientists worked on systems with bacteria that could result in industrial applications (hey, there isn't much new under the sun). One of this scientists was Chaim Weizmann (who would later become Israel's first president) who in 1916 used a bacteria called Clostridium actobutylicum to produce acetone, which was then used for the manufacturing of explosives. This process, called Acetobutilic Fermentation (ABE), gave two interesting byproducts: ethanol and butanol.
The process was used in several countries until the 1950s, when new systems to obtain acetone from oil were discovered. It's making a comeback.
Related:
[Source: Consumer]
Reader Comments (Page 1 of 1)
rgseidl 8:50PM (9/24/2007)
The problem with ABE is that yields are low because the particular strain of bacteria you mention cannot tolerate high concentrations of their own metabolic waste product butanol in the growing medium. Butanol has four isomers with different properties, include octane numbers.
ButylFuelLLC, BP and DuPont are some of the companies tackling the yield issue, in collaboration with universities. One alternative bacteria species that has been investigated is clostridium beijerinckii. See e.g. here:
http://www.ingentaconnect.com/content/hum/abab/2002/00000099/F0030001/art00012
Traditional biobutanol fermentation systems require pure glucose solution as the input. Cellulosic materials can be broken down into a mix of sugars, primarily glucose and xylose. Ideally, you'd want bacterial fermentation systems that can produce useful amounts of butanol and/or ethanol directly from this mix, preferably with as little as possible butyric acid.
http://www.springerlink.com/content/r16r811051267830/
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=171883
Note that biobutanol is considered a potential substitute for bulk gasoline whereas ethanol is used as an oxygenate and octane improver. The upper limit for butanol content is defined primarily by the official fuel formulations for gasoline, which specify permissible ranges for density, oxygen content etc. Engine designers assume that on-road fuel grades satisfy these specifications.
The acetone that is always co-produced with biobutanol is a useful feedstock for various plastics. Perhaps it could also be used as a fuel component but it is a powerful solvent, so the whole fuel system would have to be designed to handle it. Like ethanol, it is highly miscible in water, i.e. it is highly hygroscopic. That means neither can be transported in pipelines due to an elevated risk of corrosion. By contrast, butanol separates out of aqueous solution at concentration above 11%.
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Scott 9:36AM (9/25/2007)
What is the appeal of biobutanol? Current ICEs can't use it, right? That means there is no market for it until such ICEs are produced. Is butanol a byproduct of popular ethanol production methods, and companies want to find a market for it? If so, perhaps turbines driven by butanol combustion would be a better route than ICEs.
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1985 Gripen 12:40PM (9/25/2007)
Scott: wrong. Actually current ICE cars can use straight butanol without modification, unlike ethanol. It also has a higher energy content so you don't get quite the decrease in fuel economy running on butanol instead of gasoline that you do when running on ethanol.
Most current ethanol production facilities could be converted to produce biobutanol at very little expense and modification.
Further, as rgseidl (as best I can tell as I don't "speak chemistry) points-out you can run 100% butanol in your existing car whereas you can't run more than say E15 in most cases without modification. So ethanol in most cases would be a fuel additive whereas butanol could be the fuel itself.
Read the link at the beginning of the ABG 'blog post for the virtues of bio-butanol.
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