Biomass As A Source Of Raw Materials

 http://www.sciencedaily.com/releases/2009/05/090512102549.htm

Biomass As A Source Of Raw Materials


Scientists have now developed a new catalytic process to convert
components of bio-oil directly into alkanes and methanol. The process
is based on a “one-pot” reaction catalyzed by a precious metal on a
carbon support combined with an inorganic acid. (Credit: Copyright
Wiley-VCH)ScienceDaily (May 18, 2009) — For the protection of the
environment, and because of the limited amount of fossil fuels
available, renewable resources, such as specially cultivated plants,
wood scraps, and other plant waste, are becoming the focus of
considerable attention.

Processes such as pyrolysis or liquefaction allow the conversion of
biomass into bio-oil, a highly promising renewable source of energy. A
team of German and Chinese scientists led by Johannes A. Lercher at
the Technical University of Munich has now developed a new catalytic
process to convert components of bio-oil directly into alkanes and
methanol. As reported in the journal Angewandte Chemie, the process is
based on a “one-pot” reaction catalyzed by a precious metal on a
carbon support combined with an inorganic acid.

Bio-oil is an aqueous, acidic, highly oxidized mixture. However, its
high oxygen content and instability turn out to have a negative
impact: bio-oil cannot be used directly as a liquid fuel. It would,
however, be highly interesting as a source of basic raw materials if
it were possible to convert it to alkanes. Alkanes, which are also
commonly called paraffins, are saturated hydrocarbons; they are among
the most important raw materials for chemical industry, and in
particular as starting materials for the production of plastics.
Furthermore, they are among the primary fuels in the world’s economy.

Bio-oil contains a phenolic fraction consisting of compounds with the
main framework being an aromatic ring made of six carbon atoms with
some hydroxy (-OH) groups attached. With the new process, the phenolic
components of bio-oil can be converted with high selectivity to
cycloalkanes (ring-shaped alkanes) and methanol. The researchers were
able to demonstrate this with various model substances. As catalyst,
they used palladium metal on a carbon support, with phosphoric acid as
the proton source for the reaction.

The reaction is a “one-pot” reaction, meaning a one-step reaction
whose partial reactions (hydrogenation, hydrolysis, and dehydration)
occur in the same reactor, with no intermediate work-up. The secret is
in the catalyst, which works on all of these different reactions. The
end result is a mixture of various alkanes that separates into a
second phase, making it easy to separate from the aqueous bio-oil
phase. The new process is a practical approach for the direct use of
bio-oil for the production of alkanes.


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Journal reference:

1.. Highly Selective Catalytic Conversion of Phenolic Bio-Oil to
Alkanes. Angewandte Chemie International Edition 2009, 48,
4047%u20134050 DOI: 10.1002/anie.200900404
Adapted from materials provided by Wiley-Blackwell.
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