Environmental Engineering Reference
In-Depth Information
600°C
Charcoal
500°C
Phenols,
methanol
400°C
Anhydrosugurs
(levoglucosan),
hydroxymethylfurfural
300°C
Acids (acetic acid),
furans (furfural)
200°C
Extractives
(terpenes, lipids)
100°C
Moisture
(drying)
Use of catalysts
Overlapping thermochemical stability
complicates selective product devolatilisation!
Torrefaction for
enhanced wood fuels (250-290ºC)
Fast pyrolysis for
bio-oil (450-550ºC)
Carbonization
for charcoal
100ºC
200ºC
300ºC
400ºC
500ºC
600ºC
Lignin
Cellulose
Hemicellulose
Drying
FIGURE 15.5 Stepwise pyrolysis for generation of different classes of chemical compounds.
(Source: Reproduced with permission from De Wild et al. (2011). © Future Science Ltd.)
It is aimed at closing different elemental cycles. Thus, based on a wide variety of bio-
mass input, even very wet biomass
as torrefaction can be performed under hydro-
thermal conditions (see Chapter 12)
the following classes of energy carriers and
compounds can be generated:
￿
Gaseous fuels
￿
Transportation fuels
￿
Base chemicals, both organic and inorganic
￿
Fertilizers
￿
Fine chemicals and wood impregnation organics
￿
Clean water
￿
Heat and power
Another concept has been published by De Wild et al. (2011) (see Figure 15.5),
which illustrates that pyrolysis as thermochemical conversion technology can be used
in a stage-wise manner by increasing the temperature so as to produce different classes
of compounds until a charcoal is produced, which can have multifunctional use.
Catalysts are needed to selectively produce targeted products.
15.2.2
(Bio)chemical Biorefinery Concepts
Biorefineries based on biochemical conversion technologies make use of lower tem-
perature processes, and processing takes place in the aqueous phase. Pretreatment is
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