28
reactor) which is constantly produced throughout the process, thus avoiding the
concern of selecting an adequate catalyst that is easy to regenerate.
Biochar formed via TCR can be considered as an inexpensive sacrificial catalyst.
It has excellent chemical and morphologic characteristics such as structure, surface
area and high active sites, making this carbonized solid catalytically active in converting organic vapours to high-quality pyrolysis liquids [139, 145]. It has been
proven that upgrading treatment of the volatiles before their condensation is presently the most efficient way to minimize the amount of water and oxygen in the
pyrolysis liquid, which leads to a higher calorific value bio-oil composed of low
molecular weight elements [81].
7.6 Hydrotreatment
Hydrotreatment reaction removes O 2 as water and CO 2 by a catalytic reaction with
H 2 . Active catalysts for a hydrotreatment reaction are Co–Mo and Ni–Mo supported
on Al 2 O 3 and zeolites. Pindoria et al. tested hydrotreatment upgrading in a two-step
reactor. In the first step, hydrocracking was performed without catalysts, and in the
second step, zeolite catalytic hydrotreatment was operated with the same pressure
(4 MPa) but lower temperatures (300–400 °C) in comparison with the first step
[175]. The experiment showed that the zeolite catalyst becomes deactivated during
the reaction not because of the carbon content but because of volatile component
embodiments which block the zeolite active sites. The hydrotreatment process
formed a lot of water and some impure bio-oils [175]. Furthermore, this process
needs superior techniques and complicated equipment and has a high cost [82].
7.7 Aqueous Phase Processing
Aqueous phase reforming (APR) of materials such as glucose, glycerol and sorbitol
can produce light alkanes and hydrogen in a single reaction vessel. Alkane production is performed with a bifunctional reaction pathway which forms hydrogen and
CO 2 at low temperatures (150–265 °C) on an active metal catalyst such as Pd or Pt
and then dehydration of sorbitol over a solid acid catalyst (alumina and silica).
These steps are followed on the metal catalyst by hydrogenation of the dehydrated
reaction intermediates. The produced hydrogen converts sorbitol into an alkane,
CO 2 and H 2 O. A large bio-oil fraction is water- soluble, and the aqueous phase contains mainly oxygenated hydrocarbons [176–178].
H. Jahangiri et al.
reactor) which is constantly produced throughout the process, thus avoiding the
concern of selecting an adequate catalyst that is easy to regenerate.
Biochar formed via TCR can be considered as an inexpensive sacrificial catalyst.
It has excellent chemical and morphologic characteristics such as structure, surface
area and high active sites, making this carbonized solid catalytically active in converting organic vapours to high-quality pyrolysis liquids [139, 145]. It has been
proven that upgrading treatment of the volatiles before their condensation is presently the most efficient way to minimize the amount of water and oxygen in the
pyrolysis liquid, which leads to a higher calorific value bio-oil composed of low
molecular weight elements [81].
7.6 Hydrotreatment
Hydrotreatment reaction removes O 2 as water and CO 2 by a catalytic reaction with
H 2 . Active catalysts for a hydrotreatment reaction are Co–Mo and Ni–Mo supported
on Al 2 O 3 and zeolites. Pindoria et al. tested hydrotreatment upgrading in a two-step
reactor. In the first step, hydrocracking was performed without catalysts, and in the
second step, zeolite catalytic hydrotreatment was operated with the same pressure
(4 MPa) but lower temperatures (300–400 °C) in comparison with the first step
[175]. The experiment showed that the zeolite catalyst becomes deactivated during
the reaction not because of the carbon content but because of volatile component
embodiments which block the zeolite active sites. The hydrotreatment process
formed a lot of water and some impure bio-oils [175]. Furthermore, this process
needs superior techniques and complicated equipment and has a high cost [82].
7.7 Aqueous Phase Processing
Aqueous phase reforming (APR) of materials such as glucose, glycerol and sorbitol
can produce light alkanes and hydrogen in a single reaction vessel. Alkane production is performed with a bifunctional reaction pathway which forms hydrogen and
CO 2 at low temperatures (150–265 °C) on an active metal catalyst such as Pd or Pt
and then dehydration of sorbitol over a solid acid catalyst (alumina and silica).
These steps are followed on the metal catalyst by hydrogenation of the dehydrated
reaction intermediates. The produced hydrogen converts sorbitol into an alkane,
CO 2 and H 2 O. A large bio-oil fraction is water- soluble, and the aqueous phase contains mainly oxygenated hydrocarbons [176–178].
H. Jahangiri et al.