Page 263 - Biosystems Engineering

Biomass Pyr olysis and Bio-Oil Refineries 241

using a series of unit operations (Fernando et al. 2006). Bridgwater
(2005) cited the separation of phenolics for the production of resins
with the use of the remaining aqueous phase to produce hydrogen at
NREL, and the production of liquid smoke and other specialty chem-
icals with the burning of the remaining organics in boilers—only two
examples of the bio-oil–based refineries implemented. However,
many other concepts could be developed following some of the sepa-
ration schemes described by Fagernas (1995), Oasmaa et al. (1997),
and Mohan (2006). The development of several new bio-oil–based
refinery concepts is possible today thanks to the important progress
made in the last 20 years in the production, separation, and uses of
bio-oils (Czernik and Bridgwater 2004; Bridgwater 2005).
The potential exists to integrate several of the products described
in the previous section into a new bio-oil biorefinery concept allow-
ing the full utilization of crude bio-oils. For example, the organic
compounds present in family A could be separated in a scheme simi-
lar to the one used in the old wood-distillation industry (Klar and
Rule 1925) to produce salts from the acids (Oehr et al. 1993) and distil-
lated spirits rich in methanol. These compounds could be also
reformed to produce part of the hydrogen needed to hydrotreat bio-
oils. The hydroxyacetaldehyde could be recovered using a concept
very similar to the one presently used by Red Arrow Products (Him-
melblau et al. 1991). The water-soluble fraction rich in sugars, furans,
and polar oligomers could be used as a feedstock for the production
of more hydrogen either using vapor or liquid reforming (Czernik
et al. 2002; Rioche et al. 2005; Huber and Dumesic 2006) or as a feed-
stock for the production of hydrocarbons through aqueous phase
catalytic processing or via bio-oil hydrotreatment (Huber and Dume-
sic 2006). Phenol formaldehyde resins could be produced using the
pyrolytic lignin precipitated from the bio-diesel insoluble fraction
(Himmelblau et al. 1991; Chum and Kreibich 1993; Roy et al. 2000;
Giroux et al. 2001).
New separation strategies will have to be developed to cope with
the unique properties of bio-oils. For example, the difficulties of dis-
tilling a reactive material with a tendency to polymerize, as well as
the lack of viable products from biopitches, has been commonly cited
as hurdles against distillation at the core of bio-oil–based biorefiner-
ies. Several new products, such as polyurethane elastomers and bio-
carbon electrodes, have been recently developed from biopitches
(Carvalho et al. 1999; Coutinho et al. 2000; Araujo and Pasa 2002, 2003,
2004; Rocha et al. 2002), making distillation-based refineries more
attractive. The use of advanced distillation techniques such as molec-
ular distillation remains practically unexplored.
Although there is considerable room for innovation and creativ-
ity to develop new concepts for bio-oil refineries, using the infrastruc-
ture created by the petroleum industry seems to be the fastest way to
deploy this technology. In this regard, bio-oil hydrotreatment to