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Development of NiO/CeO2 for hydrogen production via
chemical looping reforming of methane
Apichaya Yahom1
, Jonathan Powell2
, Varong Pavarajarn1
, Patiwat Onbhuddha3
, Sumittra Charojrochkul3
, and Suttichai
Assabumrungrat1*
1 Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand
2 Newcastle University International – Singapore, School of Chemical Engineering and Advanced Materials, Faculty of Science, Agriculture and Engineering,
Newcastle University, NE1 7RU, United Kingdom
3 National Metal and Materials Technology Center (MTEC), 114 Paholyothin Road, Klong 1, Klongluang, Pathumthani, 12120 Thailand
Catalysis and Chemical Engineering
10/1/2012
Acknowledgements
Thai Research Fund
SummaryObjectives
Approach
Background – H2 production, Autothermal
reforming, Chemical Looping
Simulation Method & Results
Experimental Method & Results
Conclusions
Objectives & Approach
Study Ni/Al2O3 and Ni/CeO2 catalysts for use in SECLR and CLR
Simulation of CLR and SECLR reactors to find optimum operating conditions
Experiment – H2 purities and yields using NiO/Al2O3 and NiO/CeO in unmixed reformer reactor
Background - H2 production9 billion kg global annual production (2010)
Main production methods – Steam reformation, auto-thermal steam reformation, gasification
80 % produced by steam methane reformation
Energy intensive separation of gases
e.g. air separation unit and CO2 absorption column
Catalysts – most commonly used is Ni on various ceramic supports including Al2O3
Background - Chemical looping reforming of methane
Chemical Looping Reforming (CLR) of Methane
Example reactions in fuel reactorOxidation and partial oxidation of methane
Steam methane reformation
Carbon dioxide methane reformation
Water gas shift reaction
Sorption Enhanced Chemical Looping Reforming of Methane
(SECLR)
In situ adsorption of CO2
Promotes production of hydrogen via the following reversible reactions
Adsorbed CO2 can be sequesteredIncreased yield and purity of H2
Simulation Objectives & Approach
Identify nominal optimum operating conditions for CLR and SECLR of CH4 with NiO, which can then be used for experiments
Gibbs minimization method
Hydrogen yield and purity found for various; TemperaturesSteam/Methane ratiosNiO/Methane feed ratios
Simulated Chemical Looping Reforming (CLR) process
FUEL-REA
CH4+H2O
NIO
H2+NICYCLONE1
H2
NI
AIR-REA
AIR
N2+NIO
CYCLONE2
N2
H2,150C N2,150C
REACTAN2
HX1 HX2
REACTAN1
Simulated Sorption Enhanced CLR (SECLR) process
CH4+H2O
NIO-CAO
H2+SOLID
H2
NI+CACO3
CO2+SOLI
FUEL-REA
CYCLONE1
CALCINA
CYCLONE2
CO2
NI+CAO
AIR-REA
AIR
N2+SOLID
CYCLONE3
N2
H2,150C CO2,150C
REACTAN1 REACTAN2
N2,150C
HX2
REACTAN3
HX3HX1
Summary of Simulation Results
CLR nominal optimum operating conditions T > 800oC, H2O/CH4 ratio > 3, NiO/CH4 < 1
H2 yield 2.5 and H2 purity 75 %
SECLR nominal optimum operating conditions500oC > T < 600oC, H2O/CH4 ratio > 2,
NiO/CH4 < 1
CaO/CH4 > 1, H2 yield 3 and H2 purity > 90 %
Simulation validated using results from Ryden and Ramos
Rydén, M., Ramos, P., 2012. H2 production with CO2 capture by sorption enhanced chemical-looping reforming using NiO as oxygen carrier and CaO as CO2 sorbent. Fuel Processing Technology 96, 27-36
Experimental Method
Unmixed reforming reactor (with and without CaO)
ExperimentalObjective - Study change in H2 yield and purity with time (representing a change in NiO/CH4 and CaO/CH4)
Materials; Oxygen carriers – NiO/Al2O3, NiO/CeO2
Fuel – MethaneCO2 adsorber – CaO
SiC diluent
Operating conditions; T = 600oCP = 1
atmSteam/
CH4 feed = 2:1
Experimental Setup
CH4 = 2x10-6 mol/s
H2O = 4x10-6 mol/s
Total flow = 50 ml/min @ 600oC, 1 bar
Fixed bed reactor
Carrier gas
21 vol%
15
Sample Preparation
Experimental Results - H2 yield
0 5 10 15 25 35 45 55 650
0.2
0.4
0.6
0.8
1
Time (min)
HydrogenMethaneCarbon monoxideCarbon dioxide
Pro
du
ct/C
H4
feed
(m
ol/m
ol)
NiO/Al2O3
0 5 10 15 25 35 45 55 650
0.2
0.4
0.6
0.8
1
Time (min)
Pro
du
ct/C
H4
feed
(m
ol/m
ol)
NiO/CeO2
No
CaO
With
CaO
0 5 10 15 25 35 45 55 650
0.10.20.30.40.50.60.70.80.9
1
Time (min)
Pro
du
ct/C
H4
feed
(m
ol/m
ol)
0 5 10 15 25 35 45 55 650
0.2
0.4
0.6
0.8
1
Time (min)
Pro
du
ct/C
H4
feed
(m
ol/m
ol)
Experimental Results - H2 purityNiO/Al2O3 NiO/CeO2
No
CaO
With
CaO
0 5 10 15 25 35 45 55 650
0.2
0.4
0.6
0.8
1
Time (min)
Mol
e fr
acti
on
0 5 10 15 25 35 45 55 650
0.10.20.30.40.50.60.70.80.9
1
Time (min)
HydrogenMethaneCarbon monoxideCarbon dioxide
Mol
e fr
acti
on
0 5 10 15 25 35 45 55 650
0.10.20.30.40.50.60.70.80.9
1
Time (min)
Mol
fra
ctio
n
0 5 10 15 25 35 45 55 650
0.10.20.30.40.50.60.70.80.9
1
Time (min)
Mol
fra
ctio
n
Experimental Results - H2 purity
Packed bed composition Max H2 purity
NiO/Al2O3+SiC 60.80
NiO/Al2O3+CaO 65.45
NiO/CeO2+SiC 65.70
NiO/CeO2+CaO 72.36
ConclusionsCeria as a support of Ni catalyst, promotes hydrogen yields and purity in CLR and SECLR
Ceria previously shown to act as an oxygen carrier in chemical looping combustion
In situ CO2 adsorption using CaO promotes hydrogen yield and purity in SECLR