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