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: Suttichai.A@chula.ac.th

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

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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

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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%

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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

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Results and discussion

• Reduction

• Oxidation

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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

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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 %

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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 %

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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 %

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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 %

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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

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Oxidation

• 1 g NiO/Al2O3 + 1 g SiC

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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

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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

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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

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Results and dicussion

• EDX

Oxygen carrier % Weight carbon  NiO/Al2O3 2.83NiO/CeO2 1.79  

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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.

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

Conclusions

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• 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

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Acknowledgements

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

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