1. STEAM REFORMING OF COAL TAR BY USING CHEMICAL-LOOPING CARRIERS
The 1st Australia-Japan Symposium on Carbon Resource Utilisation
STEAM REFORMING OF COAL TAR BY USING CHEMICAL-LOOPING CARRIERS
Melbourne, Australia November 2016
Department of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University
Battsetseg Tsedenbal, Naokatsu Kannari and Takayuki Takarada

2. COAL Coal will be still keeping as very important energy source.
It has rich resources with stable low price, distributed widely all over the world.
Fig.1 World power generation by source in 2014 and 2040
The future use of coal faces challenges such as high efficiency, low pollution and reduced CO2 emission.
Reference: World Energy Outlook 2015

3. CARBON CAPTURE TECHNOLOGY
Carbon Capture Technologies: Pre-Combustion, Post-combustion, Oxy-combustion. However these CO2 capturing technologies may increase the energy consumption of power plant by 25-40%.
Chemical-looping process
CO2-enriched flue gas
No energy loss for CO2 capture
Fuel Reactor (Reduction)
Air Reactor (Oxidation)
MexOy
MexOy-1
Fuels
Air
CO2/H2O
N2/O2
Gaseous
Solids
H2O(l)
CO2
MexOy-1+½O2→MexOy+Heat
Fuel+MexOy→MexOy-1+H2O+CO2
Fig.2 Schematic diagram of chemical-looping process 3

4. Coal reactions in the fuel reactor
PYROLYSIS
CHAR
GASES
(CO, H2, CH4, CO2, H2O, etc.)
Primary TAR
(Heavy hydrocarbons, etc.)
REFORMING
GASIFICATION
CRACKING Products
(CO, H2, CH4, CO2, H2O, Light hydrocarbons, etc.)
CO, H2, CH4, CO2, H2O,
unconverted carbon
CL OXYGEN CARRIER
Unconverted Gas
(CO, CH4)
Unconverted
carbon
Carbon Stripper
Oxygen Polishing
CO2, H2O
Fig.3 Coal reactions in the fuel reactor of chemical looping process

5. THE OBJECTIVE Tar removal
By performing steam reforming experiment of coal tar under chemical-looping conditions, to investigate the reactivity of Fe-based chemical-looping carriers for tar reforming.
Natural Fe-based carrier: Ilmenite FeTiO3
Synthetic Fe-based carrier: Fe2O3/Al2O3
Tar removal
COAL
TAR
causes operation failure due to clogging
and blockage of pipeline

6. SAMPLES Adaro coal: Subbituminous (Indonesia)
Particle size: 1.0mm
Table 1 Proximate and Ultimate analyses of Adaro Coal
Proximate analysis (wt%, d.b.)
Ultimate analysis (wt%, d.b.)
V.M.
Ash
F.C. C H N S
Odiff
42.9
2.9 44
71.0
5.01
0.62
0.11
19.1
Natural oxygen carrier: Ilmenite FeTiO3 (Australia)
Particle size: μm
Synthetic oxygen carrier: Fe2O3/Al2O3 provided by JCOAL
Table 2 Metal composition of carriers
FeTiO3
Fe2O3/Al2O3
Fe (wt%)
Ti (wt%)
Fe (%)
Al (%)
51.5
43.8
57.8
39.5

7. TAR REFORMING EXPERIMENT
Thermocouples
Reforming temperature
900℃
Steam generator
Micro　Feeder
on/off
Experimental condition Gas flow: N₂+Steam
120ml/min
S/C ratio: 0.5
Upper furnace: 25℃ to 900℃
Heating rate: 10℃/min　　
Lower furnace: 900℃
Coal: 1.0g
Furnaces
Calculation
of gas yield
Carrier: 3.5g
Water trap
Gas bag
Heavy tar trap
(silica wool)
Product gas
Water-soluble tar
TOC
GC-FID
GC-TCD
Fig.4　Experimental apparatus

8. COMBUSTION OF SOOT, CHAR AND HEAVY TAR
Thermocouples
CHAR
SOOT
HEAVY TAR
Gas bag O₂
Combustion gas
GC-FID
Calculation
of carbon yield
Experimental condition Gas flow： O₂ 90 ml/min
Heater: 25℃ to 750℃ for 30 min
Holding time: min
Fig.5 Experimental apparatus for combustion

9. The Carbon balance after steam reforming
Results & Discussion:
Char
Soot
Gas
Heavy tar
Light tar
Carbon balance （with Char）
Carbon balance （wo Char）
Light tar
Heavy tar
Gas
Char
Soot
Sand
FeTiO3
Fe2O3/Al2O3
Sand
FeTiO3
Fe2O3/Al2O3
・ The carbon yield of tar was decreased by using chemical looping carriers.
FeTiO3, Fe2O3/Al2O3 promotes tar decomposition.

10. Tar deposits after steam reforming
Results & Discussion:
Tar deposits after steam reforming
Sand
FeTiO3
Fe2O3/Al2O3
Tar deposit
　Sand 　 > 　　　　FeTiO3 　>　 Fe2O3/Al2O3

11. Ilmenite-Reactivity for tar decomposition
Carbon balance （wo Char）
Product gas yield
Light tar
C2, C3
Heavy tar
CH4
CO2 CO
Gas H2
Soot
Sand
FeTiO3
Fe2O3/Al2O3
Sand
FeTiO3
Fe2O3/Al2O3
As FeTiO3 is used as a carrier
Heavy tar↓, Light tar↑, Soot↑　 Heavy tar cracking
No big difference of gas component No oxidation by ilmenite
CmHn (heavy) → CjHk(Light tar)

12. Fe2O3/Al2O3-Reactivity for tar decomposition
Carbon balance （wo Char）
Product gas yield
Light tar
C2, C3
Heavy tar
CH4
CO2 CO
Gas H2
Soot
Sand
FeTiO3
Fe2O3/Al2O3
Sand
FeTiO3
Fe2O3/Al2O3
As FeTiO3 is used as a carrier
Heavy tar↓, Light tar↓, Gas↑　
H2↓, CH4↓, CO2↑
CmHn + Fe2O3(Al2O3)→ CO2 + H2O + Fe/FeO(Al2O3)
C + Fe2O3(Al2O3) → CO2 + Fe/FeO(Al2O3)
CO + Fe2O3(Al2O3) → CO2 + Fe/FeO(Al2O3)
CH4 + Fe2O3(Al2O3) → CO2 + H2O + Fe/FeO(Al2O3)
H2 + Fe2O3(Al2O3) → H2O + Fe/FeO(Al2O3)

13. XRD profiles of carriers after steam reforming
Results & Discussion:
XRD profiles of carriers after steam reforming
Ilmenite
Fe2O3/Al2O3
FeTiO3
Fe2O Al2O Fe3O4 FeAl2O4
After steam reforming
After steam reforming
Fe2O3 + Volatiles → FeAl2O4
Fresh FeTiO3
Fresh Fe2O3/Al2O3
・Ilmenite(FeTiO3): No crystal structural change
・Fe2O3/Al2O3：reduced to FeAl2O3 by volatiles

14. Carrier Reactivity for TPR & TPO
Results & Discussion:
Carrier Reactivity for TPR & TPO
TG-TPO
TG-TPR
Fe2O3/Al2O3
FeTiO3
FeTiO3
Fe2O3/Al2O3
Reduction: Oxidation:
Fe2O3/Al2O3 + 3H2 → 2Fe/Al2O3 + 3H2O
Fe/Al2O3/ + 3/2O2 → Fe2O3/Al2O3
FeTiO3 + H2 → Fe + TiO2 + H2O
2Fe + TiO2 + 3/2O2 → Fe2TiO5
Comparing to FeTiO3,
Redox reaction of Fe2O3/Al2O3 is occurred at lower temperature with higher velocity.
Fe2O3/Al2O3 was more reactive and showed a higher tar reforming activity.

15. Conclusions
We investigated the reactivity of 2 iron-based chemical looping carriers for tar reforming.
Both natural and synthetic iron-based carriers have activity for tar reforming.
Fe2O3/Al2O3 has higher tar conversion and considered the following reactions.
It indicates that the reactivity of carriers depends on their redox reactivity.
CmHn + Fe2O3(Al2O3)→ CO2 + H2O + Fe/FeO(Al2O3)
C + Fe2O3(Al2O3) → CO2 + Fe/FeO(Al2O3)
CO + Fe2O3(Al2O3) → CO2 + Fe/FeO(Al2O3)
CH4 + Fe2O3(Al2O3) → CO2 + H2O + Fe/FeO(Al2O3)
H2 + Fe2O3(Al2O3) → H2O + Fe/FeO(Al2O3)

16. Thank you for your kind attention