21
represented in Fig. 9. TCR procedure has two crucial stages which are (1) intermediate pyrolysis at mild temperatures in which biomass thermal heating happens in
the absence of oxygen and (2) reforming step at raised temperatures in which vapour
catalytic cracking occurs to improve the formation of organic vapours and syngas
with superior physicochemical properties [129].
In the TCR technology, the intermediate pyrolysis step happens at 400–500 °C in
an auger reactor with solid residence times between 5 and 10 min [133]. Biochar is
being formed during the intermediate pyrolysis of biomass in the auger reactor, and
then it is collected in the reforming section (fixed bed reactor). The reforming treatment is executed between produced vapours and biochar, thus generating a catalytic
effect in all products and enhancing their physicochemical properties [134].
The post-reformer temperature is between 500 and 700 °C [135]. The higher
temperature of post-reformer produces a higher yield of syngas. The upgraded
vapours are then condensed and generate three different products which are syngas
fraction (27–44 wt%), a bio-oil fraction (6–11 wt%) and an aqueous phase
(21–26 wt%). The significant compounds of syngas are H 2 and methane [134].
During the reforming step, different kinds of chemical reactions take place, which
are as follows [72]:
1. C + H 2 O ↔ H 2 + CO (Water gas reaction).
2. CO + H 2 O ↔ CO 2 + H 2 (Water gas shift reaction).
3. CH 4 + H 2 O ↔ CO + 3H 2 (Steam reforming reaction).
4. C + 2H 2 ↔ CH 4 (Hydrogasification reaction).
5. CO 2 + C ↔ 2CO (Boudouard reaction).
6. C + ½O 2 ↔ CO (Partial oxidation reaction).
Fig. 9 TCR process flow diagram (PFD). (Reproduced with permission from [131], Copyright ©
2020, Elsevier)
Thermochemical Conversion of Biomass and Upgrading of Bio-Products to Produce…
represented in Fig. 9. TCR procedure has two crucial stages which are (1) intermediate pyrolysis at mild temperatures in which biomass thermal heating happens in
the absence of oxygen and (2) reforming step at raised temperatures in which vapour
catalytic cracking occurs to improve the formation of organic vapours and syngas
with superior physicochemical properties [129].
In the TCR technology, the intermediate pyrolysis step happens at 400–500 °C in
an auger reactor with solid residence times between 5 and 10 min [133]. Biochar is
being formed during the intermediate pyrolysis of biomass in the auger reactor, and
then it is collected in the reforming section (fixed bed reactor). The reforming treatment is executed between produced vapours and biochar, thus generating a catalytic
effect in all products and enhancing their physicochemical properties [134].
The post-reformer temperature is between 500 and 700 °C [135]. The higher
temperature of post-reformer produces a higher yield of syngas. The upgraded
vapours are then condensed and generate three different products which are syngas
fraction (27–44 wt%), a bio-oil fraction (6–11 wt%) and an aqueous phase
(21–26 wt%). The significant compounds of syngas are H 2 and methane [134].
During the reforming step, different kinds of chemical reactions take place, which
are as follows [72]:
1. C + H 2 O ↔ H 2 + CO (Water gas reaction).
2. CO + H 2 O ↔ CO 2 + H 2 (Water gas shift reaction).
3. CH 4 + H 2 O ↔ CO + 3H 2 (Steam reforming reaction).
4. C + 2H 2 ↔ CH 4 (Hydrogasification reaction).
5. CO 2 + C ↔ 2CO (Boudouard reaction).
6. C + ½O 2 ↔ CO (Partial oxidation reaction).
Fig. 9 TCR process flow diagram (PFD). (Reproduced with permission from [131], Copyright ©
2020, Elsevier)
Thermochemical Conversion of Biomass and Upgrading of Bio-Products to Produce…