Propanol and Butanol are considerably less toxic and less volatile than methanol.
Butanol is a much better fuel alternative,
but it is difficult to produce from sustainable sources.
The team's key finding is that their catalysts will convert beer(or specifically,
the ethanol in beer) into Butanol.
The 3-carbon alcohol, propanol(C3H7OH), is not often used
as a direct fuel source for petrol engines(unlike ethanol, methanol and Butanol), with most being directed into use as a solvent.
The company Energy
Environment International developed a method for producing Butanol from biomass, which involves the use of two separate micro-organisms
in sequence to minimize production of acetone and ethanol byproducts.
Methanol, ethanol, propanol, and Butanol are of interest as fuels because they can be synthesized chemically
or biologically, and they have characteristics which allow them to be used in internal combustion engines.
Despite these drawbacks, DuPont and BP have recently announced that they
are jointly to build a small scale Butanol fuel demonstration plant alongside the large bioethanol
plant they are jointly developing with Associated British Foods.
The first four aliphatic alcohols(methanol, ethanol, propanol, and Butanol) are of interest as fuels because they can
be synthesized chemically or biologically, and they have characteristics which allow them to be used in internal combustion engines.
This would be useful because Butanol has a higher energy density than ethanol, and because waste fibre left over from sugar crops used to
make ethanol could be made into Butanol, raising the alcohol yield of fuel crops
without there being a need for more crops to be plant.