1. Hydrogen production from methane via chemical looping reforming on NiO/CeO2
 Apichaya Yahom1, Varong Pavarajarn2, Patiwat Onbhuddha3, Sumittra Charojrochkul3, Suttichai Assabumrungrat1 *
1 Center of Excellence in Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Pathumwan, Bangkok, Thailand
2 Center of Excellence in Particle Technology (CEPT), Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Pathumwan, Bangkok, Thailand
3 National Metal and Materials Technology Center (MTEC), 114 Paholyothin Road, Klong 1,
Klongluang, Pathumthani, Thailand *

2. Outline Hydrogen production Chemical looping reforming
Metal oxides and supports
Carbon dioxide sorption
Objectives
Experimental
Results and discussion
Conclusions
Acknowledgements

3. Hydrogen production Steam reforming
CH4 + H2O CO + 3H2 ΔH298K = kJ/mol
CO + H2O CO2 + H2 ΔH298K = kJ/mol
Highly endothermic
Partial oxidation
CH4 + 1/2O CO + 2H2 ΔH298K = kJ/mol
Exothermic but less hydrogen

4. Hydrogen production Autothermal reforming
CH4 + H2O CO + 3H2 ΔH298K = kJ/mol
CO + H2O CO2 + H2 ΔH298K = kJ/mol
CH4 + 1/2O CO + 2H2 ΔH298K = kJ/mol
Combined steam reforming with partial oxidation to need less energy for hydrogen production

5. Chemical looping reforming
Like autothermal reforming
But has two reactors which air (oxygen) does not contact directly with methane that this process does not need energy for separating gas.

6. Chemical looping reforming
H2, CO, CO2 N2
Fuel
Reactor
(Reducer) Me
Air
Reactor
(Oxidizer)
MeO
Fuel, H2O
Air (O2,N2)

7. Metal oxides and supports
NiO is the most popular oxygen carrier (metal oxide) because of its high reactivity and oxygen transport capacity[1,2].
Support of oxygen carrier is the important factor to boost the reactivity.
[1] N.V. Gnanapragasam, B.V. Reddy, M.A. Rosen. Hydrogen production from coal using coal direct chemical looping and syngas chemical looping combustion systems: Assessment of system operation and resource requirements. International journal of hydrogen energy 2009;34:
[2] Alberto Abad, Juan Adánez, Francisco García-Labiano, Luis F. de Diego, Pilar Gayán, Javier Celaya. Mapping of the
range of operational conditions for Cu-, Fe-, and Ni-based oxygen carriers in chemical-looping combustion.
Chemical Engineering Science 2007;62:

8. Metal oxides and supports
Alumina support (Al2O3) is often used because it is low cost and has less tendency to agglomeration.
However, solids for chemical looping should be used many times, and one of problems is carbon formation on solids that deactivates the oxygen carriers[3].
[3] Meng Ni, Dennis Y.C. Leung, Michael K.H. Leung. A review on reforming bio-ethanol for hydrogen production. International Journal of Hydrogen Energy 2007;32:

9. Metal oxides and supports
Ceria support (CeO2) is famous in high oxygen storage that will release carbon on solid easier[4].
[4] A. Iriondo, V.L. Barrio, J.F. Cambra, P.L. Arias, M.B. Guemez, M.C. Sanchez-Sanchez, R.M. Navarro, J.L.G. Fierro.
Glycerol steam reforming over Ni catalysts supported on ceria and ceria-promoted alumina. International journal of
hydrogen energy 2010;35:

10. Carbon dioxide sorption
CaO increases hydrogen purity and makes methane conversion higher because CO2 which is adsorbed allows equilibrium of the reactions shifted[5].
[5] Shiyi Chen, Dong Wang, Zhipeng Xue, Xiaoyan Sun, Wenguo Xiang. Calcium looping gasification for high
concentration hydrogen production with CO2 capture in a novel compact fluidized bed: Simulation and operation
requirements. International journal of hydrogen energy 2011;36:

11. Objectives
Extend life of solid (metal oxide) used in chemical looping reforming.
Produce more purity of hydrogen by using CO2 sorbent.

12. Total flow = 50 ml/min @ 600oC, 1 bar
Experimental
H2O = 6 ml/min
CH4 = 3 ml/min
Total flow = oC, 1 bar
Carrier gas
21 vol%
Fixed bed reactor

13. Experimental No sorption : 1 g NiO/Al2O3 + 1 g SiC
1 g NiO/CeO2 + 1 g SiC
Sorption : 1 g NiO/Al2O3 + 1 g CaO
1 g NiO/CeO2 + 1 g CaO

14. Results and discussion
Reduction
Oxidation

15. Chemical looping reforming
H2, CO, CO2 N2
Fuel
Reactor
(Reducer) Me
Air
Reactor
(Oxidizer)
MeO
Fuel, H2O
Air (O2,N2)

16. Reactions in reduction reactors
R1 : CH4 + 4NiO CO2 +2H2O+4Ni ΔH298K = kJ/mol
R2 : CH4 + NiO CO +2H2+Ni ΔH298K = kJ/mol
R3 : CH4 + 2NiO CO2 +2H2+2Ni ΔH298K = kJ/mol
R4 : CH4 + H2O CO + 3H ΔH298K = kJ/mol
R5 : CH4 + CO CO + 2H ΔH298K = kJ/mol
R6 : H2O + CO CO2 + H ΔH298K = kJ/mol
In case of using CaO:
R7 : CaO + CO CaCO3 ΔH298K = kJ/mol

17. Reduction
1 g NiO/Al2O3 + 1 g SiC
H2 = 60.8 %

18. Reduction
1 g NiO/CeO2 + 1 g SiC
H2 = 65.7 %

19. Reduction
1 g NiO/Al2O3 + 1 g CaO
H2 = %

20. Reduction
1 g NiO/CeO2 + 1 g CaO
H2 = %

21. Chemical looping reforming
H2, CO, CO2 N2
Fuel
Reactor
(Reducer) Me
Air
Reactor
(Oxidizer)
MeO
Fuel, H2O
Air (O2,N2)

22. Reactions in oxidation reactors
R8 : Ni + ½O NiO ΔH298K = kJ/mol
In case of using CaO
R7 : CaO + CO CaCO3 ΔH298K = kJ/mol

23. Oxidation
1 g NiO/Al2O3 + 1 g SiC

24. Oxidation
1 g NiO/CeO2 + 1 g SiC

25. Oxidation
1 g NiO/Al2O3 + 1 g CaO

26. Reduction
1 g NiO/CeO2 + 1 g CaO

27. Results and discussion
solids
maximum hydrogen purity (percent)
NiO/Al2O3 + SiC
60.8
NiO/CeO2 + SiC
65.7
NiO/Al2O3 +CaO
65.45
NiO/CeO2 + CaO
72.36

28. Results and dicussion EDX Oxygen carrier % Weight carbon NiO/Al2O3
NiO/Al2O3
2.83
NiO/CeO2
1.79

29. Conclusions
Chemical looping reforming using Ni-based oxygen carrier on ceria support can produce hydrogen higher than alumina support because ceria support can release oxygen by itself to react with methane together with oxygen on metal oxide.

30. Conclusions
Moreover, after regeneration of Ni by oxidation, NiO/CeO2 has less carbon than NiO/Al2O3 that will prolong its age.

31. Conclusions
CaO as CO2 sorbent is proposed. CaO does not only adsorb CO2 from product stream but also can shift reaction, resulting in higher methane conversion and hydrogen purity.

32. Acknowledgements
The authors would like to thank the ceria support from The Thailand research fund (TRF).