Fwd to to Vo:
"Tungsten carbide as catalyst for cost-effective conversion of cellulose
into industrially useful carbon compounds"
http://www.futurepundit.com/archives/005569.html
http://www3.interscience.wiley.com/journal/26737/home/press/200837press.html?CRETRY=1&SRETRY=0
"Alternatives to fossil fuels and natural gas as carbon sources and fuel are
in demand. Biomass could play a more significant part in the future.
Researchers in the USA and China have now developed a new catalyst that
directly converts cellulose, the most common form of biomass, into ethylene
glycol, an important intermediate product for chemical industry. As reported
in the journal Angewandte Chemie, the catalyst is made of tungsten carbide
and nickel on a carbon support.
© Wiley-VCHCurrently, biomass is mainly used in the form of starch, which is
degraded to make sugars and then fermented to make ethanol. It would be
cheaper to use cellulose, which is the main component of plant cell walls
and thus the most plentiful organic compound on Earth. In contrast to starch
from corn and grain, cellulose is not a food, so there would be no
competition between its use as food or as raw material and fuel. At the
moment, cellulose is mainly processed by fermentation. However, splitting
cellulose into its individual sugar components, which can then be fermented,
is a slow and cost-intensive process. The direct conversion of cellulose
into useful organic compounds is thus an attractive alternative.
Initial reactions using various noble-metal catalysts have been developed.
Their disadvantage is that large amounts of expensive metal are needed to
break down the cellulose. On an industrial scale, these processes are thus
not economical. A less costly and more effective catalyst is needed.
A team led by Tao Zhang at the Dalian Institute of Chemical Physics (China)
and Jingguang G. Chen at the University of Delaware (Newark, USA) has now
developed just such a system. The catalyst is made of tungsten carbide
deposited on a carbon support. Small amounts of nickel improve the
efficiency and selectivity of the catalyst system: a synergetic effect
between the nickel and tungsten carbide not only allows 100 % conversion of
cellulose, but also increases the proportion of ethylene glycol in the
resulting mixture of polyalcohols to an amazing 61 %. Ethylene glycol is an
important intermediate in the chemical industry. For example, in the
plastics industry it is needed for the production of polyester fibers and
resins, and in the automobile industry it is used as antifreeze.
(2411 characters)
- Release Date: 9/24/2008 6:29 AM"
CQ
