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Professor Franz Fischer ...
... and Dr Hans Tropsch, the inventors of a
process to create liquid hydrocarbons from carbon monoxide gas and
hydrogen using metal catalysts.
Images: Max Planck Institute of Coal Research
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In 1925, Professor Franz Fischer, founding
director of the Kaiser-Wilhelm Institute of Coal Research in Mãlheim
an der Ruhr, and his head of department, Dr Hans Tropsch, applied for
a patent describing a process to produce liquid hydrocarbons from
carbon monoxide gas and hydrogen using metal catalysts. The
hydrocarbons synthesised in the process are made primarily of liquid
alkanes, also known as paraffins. Other by-products are olefins,
alcohols, and solid paraffins (waxes).
The required gas mixture of carbon monoxide and
hydrogen -the so called synthesis gas - is created through a reaction
of coke or coal with water steam and oxygen, at temperatures over 900
degrees Celsius. In the past, town gas and gas for lamps were a carbon
monoxide-hydrogen mixture, made by gasifying coke in gas works. In the
1970s it was replaced with imported natural gas (methane). Coal
gasification and Fischer-Tropsch hydrocarbon synthesis together bring
about a two-stage sequence of reactions which allows the production of
liquid fuels like diesel and petrol out of the solid combustible coal.
The second, direct method of liquifying coal was
invented a few years before Fischer-Tropsch Synthesis, in 1913 in
Hanover by Friedrich Bergius. Coal hydrogenation, now called coal
liquefaction, involves converting coal into an oil that, like crude
oil, can be processed in refineries to make petrol. The Bergius
process, however, can only be performed with brown coal and "geologically
young" black coal, called highly-volatile. For indirect coal
liquefaction, Fischer-Tropsch Synthesis can be used on all types of
coal as well as other raw materials which contain coal.
Fischer-Tropsch Synthesis took its first serious
place in industry in 1935 at Ruhrchemie in Oberhausen, now the
Ruhrchemie site of the Celanese AG chemical company. By the beginning
of the 1940s, some 600,000 tonnes of liquid hydrocarbons were produced
per year in German facilities, made from coal using Fischer-Tropsch
Synthesis. Licensed by Ruhrchemie, four facilities in Japan, as well
as a plant in France and in Manchuria, were in service. After World
War II, competition from crude oil made petrol production from coal
unprofitable. The only new production facilities were in South Africa,
for political reasons, built starting in 1950 in Sasolburg. Currently,
the two plants operated by Sason Synfuels fulfil about 28 percent of
South Africa's diesel and petrol needs, processing 45 million tonnes
of coal per year.
Synthesis gas can also be created from natural gas
- and this is less costly than from coal. Since 1993, Shell in
Malaysia (Bintulu) and PetroSA in South Africa (Mossel Bay) have been
operating industrial Fischer-Tropsch Synthesis facilities, which
produce liquid fuels from synthesis gas which comes originally from
natural gas (Gas To Liquid, GTL). A third similar plant is being built
by Sasol and Qatar Petroleum in Qatar in the Persian Gulf. Last year
nine more GTL-facilities were being planned world-wide; most of them
are to use Fischer-Tropsch Synthesis.
For a number of years, institutions in Germany have
been developing processes to create liquid fuels from biomass (Biomass
to Liquid, BTL). Among those institutions are the Forschungszentrum
Karlsruhe, the Clausthal University of Technology, and Choren
Industries GmbH, Future Energy GmbH, and a university in Freiburg.
Fischer-Tropsch Synthesis is used in all these technologies. The
synthesis gas is produced from wood, straw, and other raw materials of
plant origin.
Given the quick rise in the price of crude Max
Planck Institute of Coal Researchoil -
and the dramatic consequences of this year's hurricane season for
American oil production and processing - the US is rethinking how it
deals with its large domestic coal inventory. In 2006 the first US
coal-to-diesel production facility is planned in Gilberton,
Pennsylvania. It will use indirect coal liquefaction (Coal To Liquid,
CTL), via coal gasification and Fischer-Tropsch Synthesis. Two further
similar US projects are in discussion. China, too, has been investing
recently in CTL technology using indirect Fischer-Tropsch Synthesis.
Already in 2002 it began planning a commercial coal liquefaction (coal
hydrogenation) facility in Inner Mongolia. |
