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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, 10330 Thailand2 Center of Excellence in Particle Technology (CEPT), Department of Chemical Engineering, Faculty of
Engineering, Chulalongkorn University, Pathumwan, Bangkok, 10330 Thailand3 National Metal and Materials Technology Center (MTEC), 114 Paholyothin Road, Klong 1,
Klongluang, Pathumthani, 12120 Thailand
*E-mail: [email protected]
1
Outline• Hydrogen production• Chemical looping reforming• Metal oxides and supports• Carbon dioxide sorption• Objectives• Experimental• Results and discussion• Conclusions• Acknowledgements
2
Hydrogen production
• Steam reformingCH4 + H2O CO + 3H2 ΔH298K = 206.1 kJ/mol
CO + H2O CO2 + H2 ΔH298K = -41.2 kJ/mol
Highly endothermic• Partial oxidation
CH4 + 1/2O2 CO + 2H2 ΔH298K = -35.7 kJ/mol
Exothermic but less hydrogen3
Hydrogen production
• Autothermal reformingCH4 + H2O CO + 3H2 ΔH298K = 206.1 kJ/mol
CO + H2O CO2 + H2 ΔH298K = 206.1 kJ/mol
CH4 + 1/2O2 CO + 2H2 ΔH298K = -35.7 kJ/mol
Combined steam reforming with partial oxidation to need less energy for hydrogen production
4
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.
5
Chemical looping reforming
FuelReactor
(Reducer)
AirReactor
(Oxidizer)
H2, CO, CO2 N2
Air (O2,N2)
Me
MeO
Chemical looping reforming
Fuel, H2O 6
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.
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[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: 2606-2615.
[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;62:533-549.
• 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].
Metal oxides and supports
8[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;32:3238-3247.
• Ceria support (CeO2) is famous in high oxygen storage that will release carbon on solid easier[4].
Metal oxides and supports
9[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;35:11622-11633.
Carbon dioxide sorption
• CaO increases hydrogen purity and makes methane conversion higher because CO2 which is adsorbed allows equilibrium of the reactions shifted[5].
10[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;36:4887-4899.
Objectives
• Extend life of solid (metal oxide) used in chemical looping reforming.
• Produce more purity of hydrogen by using CO2 sorbent.
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Experimental
CH4 = 3 ml/min
H2O = 6 ml/min
Total flow = 50 ml/min @ 600oC, 1 bar
Fixed bed reactor
Carrier gas
21 vol%
12
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
13
Results and discussion
• Reduction
• Oxidation
14
Chemical looping reforming
FuelReactor
(Reducer)
AirReactor
(Oxidizer)
H2, CO, CO2 N2
Air (O2,N2)
Me
MeO
Chemical looping reforming
Fuel, H2O 15
Reactions in reduction reactors
• R1 : CH4 + 4NiO CO2 +2H2O+4Ni ΔH298K = 174.9 kJ/mol
• R2 : CH4 + NiO CO +2H2+Ni ΔH298K = 208.6 kJ/mol
• R3 : CH4 + 2NiO CO2 +2H2+2Ni ΔH298K = 169.9 kJ/mol
• R4 : CH4 + H2O CO + 3H2 ΔH298K = 206.1 kJ/mol
• R5 : CH4 + CO2 2CO + 2H2 ΔH298K = 357.8 kJ/mol
• R6 : H2O + CO CO2 + H2 ΔH298K = -41.2 kJ/mol
In case of using CaO:• R7 : CaO + CO2 CaCO3 ΔH298K = -178.8 kJ/mol
16
Time (min)
0 10 20 30 40 50 60
Mo
le f
rac
tio
n p
erc
en
t
0
20
40
60
80
100HydrogenMethaneCarbon monoxideCarbon dioxide
Reduction
• 1 g NiO/Al2O3 + 1 g SiC
H2 = 60.8 %
17
Time (min)
0 10 20 30 40 50 60
Mo
le f
rac
tio
n p
erc
en
t
0
20
40
60
80
100
HydrogenMethaneCarbon monoxideCarbon dioxide
Reduction
• 1 g NiO/CeO2 + 1 g SiC
H2 = 65.7 %
18
Time (min)
0 10 20 30 40 50 60
Mo
le f
rac
tio
n p
erc
en
t
0
20
40
60
80
100HydrogenMethaneCarbon monoxideCarbon dioxide
Reduction
• 1 g NiO/Al2O3 + 1 g CaO
H2 = 65.45 %
19
Time (min)
0 10 20 30 40 50 60
Mo
le f
rac
tio
n p
erc
en
t
0
20
40
60
80
100HydrogenMethaneCarbon monoxideCarbon dioxide
Reduction
• 1 g NiO/CeO2 + 1 g CaO
H2 = 72.36 %
20
Chemical looping reforming
FuelReactor
(Reducer)
AirReactor
(Oxidizer)
H2, CO, CO2 N2
Air (O2,N2)
Me
MeO
Chemical looping reforming
Fuel, H2O 21
Reactions in oxidation reactors
• R8 : Ni + ½O2 NiO ΔH298K = -244.3 kJ/mol
In case of using CaO• R7 : CaO + CO2 CaCO3 ΔH298K = -178.8 kJ/mol
22
Oxidation
• 1 g NiO/Al2O3 + 1 g SiC
23
Time (min)
0 10 20 30 40 50 60
Mo
le f
rac
tio
n p
erc
en
t
0
20
40
60
80
100
Carbon monoxideCarbon dioxideOxygen
Oxidation
• 1 g NiO/CeO2 + 1 g SiC
24
Time (min)
0 10 20 30 40 50 60
Mo
le f
rac
tio
n p
erc
en
t
0
20
40
60
80
100Carbon monoxideCarbon dioxideOxygen
Oxidation
• 1 g NiO/Al2O3 + 1 g CaO
25
Time (min)
0 10 20 30 40 50 60
Mo
le f
rac
tio
n p
erc
en
t
0
20
40
60
80
100
Carbon monoxideCarbon dioxideOxygen
Reduction
• 1 g NiO/CeO2 + 1 g CaO
26
Time (min)
0 10 20 30 40 50 60
Mo
le f
rac
tio
n p
erc
en
t
0
20
40
60
80
100
Carbon monoxideCarbon dioxideOxygen
Results and discussion
solidsmaximum hydrogen
purity (percent)
NiO/Al2O3 + SiC 60.8
NiO/CeO2 + SiC 65.7NiO/Al2O3 +CaO 65.45
NiO/CeO2 + CaO 72.36
27
Results and dicussion
• EDX
Oxygen carrier % Weight carbon NiO/Al2O3 2.83NiO/CeO2 1.79
28
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.
29
• Moreover, after regeneration of Ni by oxidation, NiO/CeO2 has less carbon than NiO/Al2O3 that will prolong its age.
Conclusions
30
• 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.
Conclusions
31
Acknowledgements
• The authors would like to thank the ceria support from The Thailand research fund (TRF).
32