Packed bed chemical looping and

sorption enhanced steam reforming

research at Leeds

Z.S. Abbas, R. Bloom, V. Dupont, T. Mahmud, S. J. Milne

School of Chemical and Process Engineering, The University of Leeds

Introduction to the process (Rob Bloom)

Modelling of Heterogeneous Chemical looping reforming process

in fixed bed reactor (Zaheer Syed Abbas)

Development of Novel OTMs for SECLSR (Rob Bloom)

Novel SECLSR Process Concept

Uses two packed reactors a

reformer and a

pressure/temperature swing

adsorber

3 process stages are used to

carry out the process

Achieves the production of

ready separated productions

of H2, CO2 and N2 from natural

gases

Modelling of Heterogeneous Chemical

looping reforming process in fixed bed

reactor

Zaheer Syed Abbas

Model Description

1-D heterogeneous mathematical model

Operation is adiabatic in nature

Ideal gas law is applicable

Concentration and temperature gradients along the radial direction were

negligible. So only 1-dimensional variation in concentration and

temperature i.e. in axial direction is considered.

Heterogeneous phase was considered and no temperature gradient

existed in the catalyst particles

Porosity of the bed was constant

Reaction Scheme

Reaction Reaction rate equation

CH4 g + H2O g ↔CO g + 3H2 g R1 =k1

pH22.5 pCH4

pH2O −pH23 pCO

KI

1

Ω2 Ref: [1]

CO g + H2O g ↔CO2 g + H2 g R2 =k2

pH2pCOpH2O −

pH2pCO2KIII

1

Ω2 Ref: [1]

CH4 g + 2H2O g ↔CO2 g + 4H2 g R3 =k3

pH23.5 pCH4

pH2O2 −

pH24 pCO2

KII

1

Ω2 Ref: [1]

CH4 g + CO2(𝑔)↔ 2CO g + 2H2 g R4 =k4pCH4pCO21+KCO2pCO2

Ref: [2]

CH4 g + Ni (s)↔C (s) + 2H2 g

R5 =k5KCH4,d pCH4−

pH22

Kp,d

1+1

Kr,dpH2

32 +KCH4,dpCH4

2 Ref: [2]

H2O g + C (s)↔CO (g) + H2 g

R6 =

k6KH2O,g

pH2O

pH2−pCOKp,g

1+KCH4,gpCH41

KH2O,g

pH2O

pH2+

1

Kr,gpH2

32

2 Ref: [2]

CO2(𝑔) + C (s)↔2CO (g)

R7 =

k7KCO2,g

KCO,g

pCO2pCO

−pCO2

Kp,g,CO2

1+KCO,gpCO+1

KCO2,gKCO,g

pCO2pCO

2 Ref: [2]

Reaction Reaction rate equation

CH4 g + 2NiO (s)↔2Ni (s) + 2H2 g +2CO2(𝑔) R8 = a0k8CCH4CNiOCNi(1 − X𝑁𝑖𝑂) Ref: [2]

H2 g + NiO (s)↔Ni (s) + H2O g R9 = a0k9CH2CNiO(1 − X𝑁𝑖𝑂) Ref: [2]

CO (g) + NiO (s)↔Ni (s) + CO2(𝑔) R10 = a0k10CCOCNiOCNi(1 − X𝑁𝑖𝑂) Ref: [2]

CH4 g + NiO (s)↔Ni (s) + 2H2 g +CO (g) R11 = a0k11CCH4CNiOCNi(1 − X𝑁𝑖𝑂) Ref: [2]

O2 g + 2Ni s ↔2NiO g 𝑅12 = 𝑎0𝑘12 1 − 𝑋𝑁𝑖 2 3𝐶𝑂2𝐶𝑁𝑖

′Ref: [3]

O2 g + C s ↔CO2 g 𝑅13 = 𝑎0𝑘13 1 − 𝑋𝐶 1 2𝐶𝑂2𝐶𝐶

′ Ref: [4]

O2 g + 2C s ↔2CO g 𝑅14 = 𝑎0𝑘14 1 − 𝑋𝐶 1 2𝐶𝑂2𝐶𝐶

′ Ref: [4]

O2 g + 2CO g ↔2CO2 g 𝑅15 =𝑘15𝐶𝑂2𝐶𝐶𝑂

1+𝐾𝐶𝑂,𝑜𝐶𝐶𝑂Ref: [5]

Reduction Oxidation

Experimental Setup

Experimental set-up for Sorption Enhanced Chemical Looping Steam Reforming Process

available at ERI/ SCAPE (Energy and Research Institute/ School of Chemical

and Process Engineering) ,University of Leeds

Experimental Setup

Preliminary Experiments

Diameter of catalyst [mm] Effectiveness factor Thiele modulus

1.2 0.52 4.48

1.85 0.37 6.90

0.2 0.92 1.15

Weisz-Prater (WP) criterion was used to find out the required size of the

particle. This criterion is used to find out if internal diffusion is limiting the

reaction or not.

A particle size of 200μm is required to virtually eliminate diffusion control

(i.e. ƞ = 0.92)

Calculated values for Thiele modulus and effectiveness factor

Kinetics of Steam methane

reforming

Activation Energy,

kJ/mol

Pre-exponential factor

E1 E2 E3

ko,1

(mol.bar0.5/(gs))ko,2 (mol/(bar.gs))

ko,3

(mol.bar0.5/(gs))

257.01 89.23 236.70 5.19×109 9.90×103 1.32×1010-20

-18

-16

-14

-12

-10

-8

-6

0.001 0.00116 0.00132 0.00148 0.00164 0.0018

ln k

i

1/T (K-1)

k1 k3 k2

Reduction Kinetics of 18 wt%

NiO/αAl2O3

-2.00

-1.50

-1.00

-0.50

0.00

2.00 3.00 4.00 5.00 6.00

ln [

-ln

(1-α)]

lnt

550C n = 1.92

600C n = 1.84

650C n = 1.94

700C n = 1.95

750C n = 1.98

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.90 1.12 1.34 1.56 1.78 2.00

NiO

fra

ctio

nal

conver

sion

Time [min]

a) 750°C

EXP

R2

AE2

AE1.5

D1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.90 1.12 1.34 1.56 1.78 2.00

NiO

fra

ctio

nal

conver

sion

Time [min]

b) 700°C

EXP

R2

AE2

AE1.5

D1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

1 2 3 4

NiO

fra

ctio

nal

conver

sion

Time [min]

c) 650°C

EXP

R2

AE2

AE1.5

D1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

1 2 3 4

NiO

fra

ctio

nal

conver

sion

Time [min]

d) 600°C

EXP

R2

AE2

AE1.5

D1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 70 140 210 280 350

NiO

fra

ctio

nal

Co

nv

ersi

on

Time [min]

750 C

700 C

650 C

600 C

550 C

Model fitting(AE2)

Model Validation

GHSV

(h-1)

Feed C

(moles)

C in outlet gases (moles)Exp. Cout

(moles)

Exp. Cout/Cin

(%)

CH4 CO CO2

1.62 0.030Exp: 2.2×10-3

Mod: 1.8×10-3

Exp: 1.38×10-2

Mod: 1.53 ×10-2

Exp: 1.35×10-2

Mod: 1.38 ×10-20.0295 98.30

2.58 0.049Exp: 4.13×10-3

Mod: 5.1×10-3

Exp: 2.00 ×10-2

Mod: 2.18 ×10-2

Exp: 2.32 ×10-2

Mod: 2.18 ×10-20.0472 96.33

4.54 0.086Exp: 1.85×10-2

Mod: 1.77×10-2

Exp: 2.55 ×10-2

Mod: 2.79 ×10-2

Exp: 3.60×10-2

Mod: 3.39 ×10-20.0800 93.02

Far From Equilibrium

Molar carbon balance for SMR experiments over 18wt % NiO/α-Al2O3 catalyst. Experiments were run over the duration of

4500 sec, at 700°C, 1 bar pressure and S/C of 3.0

a) Fractional Conversion of CH4 &

H2O

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000

Fra

ctio

nal

conver

sion

Time [sec]

CH4_Exp CH4_Mod

H2O_Exp H2O_Mod

(a)

0.2

0.4

0.6

0.8

1.0

0 1000 2000 3000 4000 5000

Fra

ctio

nal

conver

sion

Time [sec]

CH4_Exp CH4_Mod

H2O_Exp H2O_Mod

(c)

0.2

0.4

0.6

0.8

1.0

0 1000 2000 3000 4000 5000

Fra

ctio

nal

conver

sion

Time [sec]

CH4_Exp CH4_Mod

H2O_Exp H2O_Mod

(b)

Comparison between measured and estimated methane & water conversion at 700°C, 1 bar pressure and S/C 3. (a) 1.62 h-1 GHSV (b) 2.58 h-1 GSHV (c) 4.54 h-1 GHSV

Effect of Gas hourly space velocity

(GHSV)

0

20

40

60

80

100

1.62 3.24 4.86 6.47 8.09 9.71

Hyd

rogen

yie

ld [

wt

%]

and p

uri

ty [

%]

GHSV [hr-1]

Yield_Mod

Purity_Mod

Yield_Equ

Purity_Equ

0.0

0.2

0.4

0.6

0.8

1.0

1.62 3.24 4.86 6.47 8.09 9.71

Fra

ctio

nal

Conver

sion

GHSV [hr-1]

CH4_Mod

H2O_Mod

H2O_Equ

CH4_Equ

(a)

0

20

40

60

80

100

1.62 3.24 4.86 6.47 8.09 9.71

Sel

ecti

vit

y o

f

pro

du

ct

gas

es [

%]

GHSV [hr-1]

CH4_Mod

CO_Mod

CO2_Mod

H2_Mod

CH4_Equ

CO_Equ

CO2_Equ

H2_Equ

(b)

(c)

Gas hourly space

velocity (GHSV) plays a

vital role in overall

conversion of fuel and

performance of the

system.

The higher the GHSV,

i.e. the shorter the

residence time through

the reactor, the lower

will be the fuel

conversion of fuel due

to high gas velocities

limiting the time for

reactions to achieve

high conversions.

0.00

0.20

0.40

0.60

0.80

1.00

0 10 20 30 40 50 60

Rat

e o

f R

educt

ion (

R1,R

2,R

3&

R4)

x 1

E4

[m

ol/

g/s

]

Time [s]

Entrance of the Reactor(z = 2.00 E-04 m)

R1

R2

R3

R4

-2.00

0.00

2.00

4.00

6.00

8.00

0 10 20 30 40 50 60Rat

e o

f R

educt

ion (

R5,

R6,

R7,

R8,

R9

& R

10)

x 1

E5

[m

ol/

g/s

]

Time [s]

Entrance of the Reactor (z = 2.00 E-04 m)

R5

R6

R7

R8

R9

R10

0.00

0.10

0.20

0.30

0.40

0.50

0 10 20 30 40 50 60

Rat

e o

f R

educt

ion (

R1,R

2,R

3&

R4)

x 1

E4

[m

ol/

g/s

]

Time [s]

Middle of the Reactor(z = 3.80 E-03 m)

R1

R2

R3

R4

-2.00

0.00

2.00

4.00

6.00

8.00

0 10 20 30 40 50 60

Rat

e o

f R

educt

ion (

R5,

R6,

R7,

R8,

R9

& R

10)

x 1

E5

[m

ol/

g/s

]

Time [s]

Middle of the Reactor (z = 3.80 E-03 m)

R5

R6

R7

R8

R9

R10

Rate of reaction

0.00

0.10

0.20

0.30

0.40

0.50

0 10 20 30 40 50 60

Rat

e of

Red

uct

ion (

R1,R

2,R

3&

R4)

x 1

E4 [

mol/

g/s

]

Time [s]

Reactor exit (z = 7.652 E-03 m)

R1

R2

R3

R4

-2.00

0.00

2.00

4.00

6.00

8.00

0 10 20 30 40 50 60Rat

e of

Red

uct

ion (

R5, R

6, R

7, R

8,

R9

& R

10)

x 1

E5 [

mol/

g/s

]

Time [s]

Reactor exit (z = 7.652 E-03 m)

R5

R6

R7

R8

R9

R10

Development of Novel OTMs for

Sorption Enhanced Chemical Looping

Steam Reforming

Robert Bloom

Active Metal Selection

Use of Nickel as an OTM for SECLSR is well reported in the

literature

Cobalt has not been investigated for use in the SECLSR process

due to unwanted interactions with support materials and

difficulties with oxidation states

Bi metallic OTMs have been neglected in the SECLSR literature

Ni-Co bimetallic catalysts can offer many advantages

Novel Support Selection

Use of polycrystalline alumina fibres

as a support offers many

advantages:

• High Porosity (SSA ~150 m2/g)

• Thermally stable

• Advantageous physical properties

Novel OTM Synthesis

Ni, Co and Ni-Co supported by polycrystalline alumina has been

achieved using wet impregnation

18wt% Ni 9wt% Ni / 9wt% Co18wt% Co

Acknowledgements

We would like to thank the UK EPSRC for both the low carbon

CDT scholarship for Robert Bloom and the UKCCSRC Call 2

grant in Industrial CCS

Additionally we would to acknowledge University of

Engineering and technology (UET) Lahore, Pakistan and

University of Leeds, UK for The financial support.