Etude de la combustion de gaz de synthèse issus d'un processus de ...

Bibliographic revision
Hydrogen
Hydrogen is currently produced in large quantities via steam reforming of hydrocarbons
over a nickel catalyst at about 800ºC (Nieminen, 2004). This process produces a
syngas that must be further processed to produce high-purity hydrogen. The syngas
conditioning required for steam reforming is similar to that which would be required for
a biomass gasification derived syngas. However, tars and particulates are not so
worrying. To raise the hydrogen content, the syngas is fed to one or more water gas
shift reactors, which converts CO in H 2 according with the reaction CO + H 2 O = H 2 +
CO 2 .
Methanol
tel-00623090, version 1 - 13 Sep 2011
Methanol synthesis involves the reaction of CO, H 2 and steam in a copper-zinc oxide
catalyst in the presence of small amounts of CO 2 at a temperature of about 260ºC and
a pressure of about 70 bar (Paisley and Anson, 1997). The formation of methanol from
syngas proceeds via the following reactions:
CO + H 2 O = H 2 + CO 2 (water-gas shift reaction)
3H 2 + CO 2 = CH 3 OH + H 2 O (hydrogenation of carbon dioxide)
2H 2 + CO = CH 3 OH
Methanol production also occurs by means of direct hydrogenation of CO, but at a
much slower rate (Engstrom, 1999):
2H 2 + CO = CH 3 OH (hydrogenation of carbon monoxide)
To best use the raw product syngas in methanol synthesis and limit the extent of
additional treatment or steam reforming, it is essential to maintain the parameters
indicated in Table 2.3.
2.3. Syngas characterization
The quality of the producer gas depends upon several factors including type of fuel,
gasifier type and operational conditions (temperature, pressure and oxidizing agent).
Following each one is described.
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