kinetics of the chemical looping reduction of cuo ... of the chemical looping reduction of...
TRANSCRIPT
CFB8 - REM, 5/3/2005
Kinetics of the chemical looping reduction of CuO/bentonite by
methane (CH4)
Esmail R. Monazam1,2, Ranjani Siriwardane, Lawrence J. Shadle, George
Richard, Hanjing Tian2 , David E. Huckaby, and Stephen Carpenter2
National Energy Technology Laboratory
U. S. Department of Energy
3610 Collins Ferry Rd.
Morgantown, West Virginia 26507-08801REM Engineering Services, PLLC
3537 Collins Ferry Rd.
Morgantown, West Virginia 265052URS Energy & Construction, Inc.
3610 Collins Ferry Rd.
Morgantown, WV. 26505
CFB8 - REM, 5/3/2005
Objective
Extract kinetic parameters from experimental test data
using Thermo-gravimetric Analysis (TGA) and Mass
spectrometry (MS) on selected metal oxygen carrier
(Cu-based and Fe-based/Bentonite) developed at the
National Energy Technology Laboratory (NETL).
Thermo-gravimetric Analysis (TGA)–Used to record the change in mass of ~40 mg samples
over- time
Mass spectrometry (MS)
-Used to determining the elemental composition of a sample or molecule
CFB8 - REM, 5/3/2005
Chemical Looping
Combustion Products
CO2 , H2ODepleted Air
O2 , N2
Fuel
CnHm
MeO
Me
Air
O2 , N2
Air
Reactor
Fuel
Reactor
Oxygen is removed from air stream and transported to a fuel reactor via
a metal or other oxygen carrier. The metal must then be separated
from ash once oxygen is freed in the reactor and returned to the air
reactor
4 2 24 4 2CuO CH Cu CO H O
∆G=−590 kJ/mol, ∆H=−217 kJ/mol
2
2 2
2 2
2 2
4 2
2 4
Cu O CuO
Cu O Cu O
Cu O O CuO
Fuel Reactor
Air Reactor
CFB8 - REM, 5/3/2005
Typical mass and temperature measurement for
CuO/bentonite particle and 100% CH4 for reduction
and air for oxidation reactions
0
200
400
600
800
1000
30
32
34
36
38
40
42
44
0 500 1000 1500 2000T
emp
erat
ure
(oC
)
Mas
s (m
g)
Time (min)
dp=150-250 m
NETL TGA Data for Cu base sorbent
4 2 24 4 2CuO CH Cu CO H O
100% CH4, 800 oC
0.E+00
1.E-14
2.E-14
3.E-14
4.E-14
5.E-14
0
0.5
1
1.5
2
0 0.5 1 1.5 2
Conce
ntr
atio
n-C
H4
,CO
2
Conver
sion (
X)
Time (min)
T =900 oC
CH4
CO2
X
→
→
Conversion, X, and outlet gas analysis of CH4 and CO2
for the reduction of copper oxide (CuO) with methane
(100%CH4)
1 rr
ox r
m mX
m m
CFB8 - REM, 5/3/2005
Eight different rate equations
were indentified and examined,
including shrinking core model
(diffusion and reaction control),
linear, parabolic and cubic rate
laws, first and second order
global reaction rate, and Jonson-
Mehl-Avarmi (JMA) rate, to fit the
TGA experimental data for CuO-
bentonite/methane reduction
reaction. None of the models
gave satisfactory results over the
range of 750-900 oC with the
exception of JMA equation.
0
0.2
0.4
0.6
0.8
1
0 0.2 0.4 0.6 0.8 1
Conv
ersi
on (
X)
t/
Ideal diff. cont.
Ideal Rxn Cont.
Measured Exp. data
JMA rate
T=850 oC
Rate Analysis (Cu-base Reduction)
Typical curve fitting of experimental reduction data
using shrinking core model (diffusion and reaction
control) and JMA rates for 100% methane and 850 oC.
CFB8 - REM, 5/3/2005
Rate Analysis (Cu-base Reduction)
( )(1 )nktX e
n~kinetic exponent which depends on the
mechanism of growth and the dimensionality of
the crystal
k ~reaction rate constant, whose
temperature dependence is generally
expressed by the Arrhenius equation ,
( / )
0
E RTk k e
0
0.2
0.4
0.6
0.8
1
0 0.4 0.8 1.2 1.6 2
Co
nv
ers
ion
(X
)
Time (min)
750
800
850
900
T (oC)
Effect of reaction temperature and fitting of
Jonson-Mehl-Avarmi (JMA) equation
Jonson-Mehl-Avarmi (JMA) equation100% CH4
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5
Xre
du
ctio
n
Time (Min)
T=850 oC
20%50%
100% CH4
Effect of methane concentration on reduction
for T=850 oC
CFB8 - REM, 5/3/2005
Rate Analysis (Cu-base Oxidation)
0
0.2
0.4
0.6
0.8
1
1.2
0 2 4 6
Xre
du
cti
on
Time (Min)
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
T=850 oC20% CH4
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5
Xre
du
ctio
n
Time (Min)
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
T=850 oC50% CH4
0
0.2
0.4
0.6
0.8
1
0 1 2 3 4 5
Xre
du
ctio
n
Time (Min)
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
T=850 oC100% CH4
Reduction’s conversion increases as cycle
increased at given temperature
CFB8 - REM, 5/3/2005
0
1
2
3
0 2 4 6 8 10 12
n
# of Cycles
750
800
850
900
T (oC)
Effect of Cycles on n and k of JMA rate (CuO/CH4)
100% CH4
Diffusion controlled growth All shapes growing from small dimensions
Increasing nucleation rate >2.5
Constant nucleation rate 2.5
Decreasing nucleation rate 1.5-2.5
Zero nucleation rate 1.5
100% CH4-There is a slight increase (~10%)
in n with increasing cycles @ T= 750, 800,
and 850 oC (1.7-1.93 ) and about 30%
increase for T=900 oC (1.6-2.1) average
n=1.9.
50% CH4, n=1.6-1.74 for all T with average
n=1.66)
Rate constant, k, also increases (~20%) with
increasing cycles @ T= 750, 800, and 850 oC
and about 37% increase for T=900 oC.
0
1
2
3
0 2 4 6 8 10 12
k (m
in-1
)
# of Cycles
750
800
850
900
100% CH4
CFB8 - REM, 5/3/2005
y = -4484.2x + 4.2648
y = -4354.3x + 4.2504
y = -4316.1x + 4.0824
y = -4313.3x + 3.6573
y = -4358.7x + 3.1394
-1.4
-1
-0.6
-0.2
0.2
0.6
1
0.0008 0.00085 0.0009 0.00095 0.001
ln(d
X/d
t)
1/T (K-1)
0.2
0.4
0.6
0.8
0.9
X
Arrehenius plot for CuO/bentonite and CH4reaction
Kinetics Parameters for Reduction of Cu-base Sorbent
100%
CH4
Temperature and CH4 concentration dependence
of the rate constant, k (1/min.).
0
1ln( ) ln
dX Ek
dt R T
-1.5
-1
-0.5
0
0.5
1
0.0008 0.00085 0.0009 0.00095 0.001
ln(k
) (m
in-1
)
1/T (K-1)
E=36.5 kJ/mole
E=38.74 kJ/mole100% CH4
50%
E=36.56 kJ/mole
20%
Plot of ln(dx/dt) vs 1/T shows that activation
energy is uniform as a function of conversion
4
( 4482.34/ ) 0.654(1/ min) 91CH
Tk e y
CFB8 - REM, 5/3/2005
11
(1 )[ ln(1 )] ndX
kn X Xdt
0
0.5
1
1.5
2
0 0.5 1 1.5 2
dX
/dt
(min
-1)
Time (min)
750
800
850
900
T (oC)dX/dt,max
Rate Analysis (Cont.)
Effect of reaction temperature on the rate reduction of
CuO/bentonite particle and CH4 reaction
0.E+00
1.E-14
2.E-14
0
0.5
1
1.5
2
0 0.5 1 1.5 2
Co
nce
ntr
atio
n-
CO
2
Xr&
dX
r/d
t (m
in-1
)Time (min)
T =900 oC
dXr/dt
CO2
Xr
→
Rate reduction of CuO/bentonite particle and CO2
production
CFB8 - REM, 5/3/2005
-20
-10
0
10
20
30
40
0 2 4 6 8 10 12
(O,C
uO
-T,M
ass
lost
)x1
00
/ O
,Cu
O
Cycle #
750
800
850
900
100% CH4100% CH4
-20
-10
0
10
20
30
40
0 2 4 6 8 10 12
(O,C
uO
-T,M
ass
lost
)x10
0/O
,CuO
Cycle #
750
800
850
900
50% CH4
Mass balance during reduction of CuO with methane
CFB8 - REM, 5/3/2005
Reduction kinetics test
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100
Xre
du
ctio
n
Time (s)
model
exp
750 oC800
850
900
100% CH4
0
0.2
0.4
0.6
0.8
1
1.2
0 40 80 120 160 200
Xre
du
ctio
n
Time (s)
750 oC
850
900
50% CH4
Comparison between kinetic model predictions and experimental data at several
temperatures.
CFB8 - REM, 5/3/2005
Rate Analysis (Cu-base Oxidation)
rdOxd
oxd rd
m mX
m m
Conversion rate decreases as temperature increases
2
2 2
2 2
2 2
4 2
2 4
Cu O CuO
Cu O Cu O
Cu O O CuO
0.0
0.2
0.4
0.6
0.8
1.0
0 10 20 30 40
Conver
sion (
X)
Time (min)
750
800
850
900
T (oC)
0.0E+00
2.0E-14
4.0E-14
6.0E-14
8.0E-14
1.0E-13
1.2E-13
1.4E-13
0 20 40 60
Ga
s C
on
cen
tra
tio
n C
O2,
O2
Time (min)
750
800
850
900
T (oC)
O2
CO2
Effect of reaction temperature on oxidation
conversion for Cycle #5
Effect of reaction temperature on CO2 and O2
gas concentration
100% CH4 reduction
CFB8 - REM, 5/3/2005
Rate Analysis (Cu-base Oxidation)
rdOxd
oxd rd
m mX
m m
Conversion rate decreases as temperature increases
2
2 2
2 2
2 2
4 2
2 4
Cu O CuO
Cu O Cu O
Cu O O CuO
Effect of reaction temperature on oxidation
conversion for Cycle #5
Effect of reaction temperature on CO2 and O2
gas concentration
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20
XO
xd
Time (Min)
750
800
850
900
T (oC)
50%CH4
0.0E+00
2.0E-14
4.0E-14
6.0E-14
8.0E-14
1.0E-13
1.2E-13
1.4E-13
0 10 20 30 40 50 60
Gas
Co
ncentr
ati
o (
O2,C
O2)
Time (min)
750
800
850
900
T (oC)
O2
CO2
CFB8 - REM, 5/3/2005
0.0E+00
2.0E-14
4.0E-14
6.0E-14
8.0E-14
1.0E-13
1.2E-13
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30
Gas
Conce
ntr
atio
n
Conv
ersi
on (
X)
Time (min)
O2
CO2
Cycle #5 Oxid.T=850 oC
100% CH4 Red.
0.0E+00
2.0E-14
4.0E-14
6.0E-14
8.0E-14
1.0E-13
1.2E-13
1.4E-13
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30
Gas
Co
nce
ntr
atio
n
Co
nver
sio
n (
X)
Time (min)
O2
CO2
Cycle #5 Oxid.T=850 oC
50% CH4 Red.
0.0E+00
2.0E-12
4.0E-12
6.0E-12
8.0E-12
1.0E-11
1.2E-11
1.4E-11
1.6E-11
1.8E-11
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Gas
Co
ncen
trati
on
Co
nvers
ion
(X
)
Time (min)
O2
CO2
Cycle #5 Oxid.T=850 oC
20% CH4 Red.
Effect of methane concentration during reduction
process on oxidation of Cu
0
0.2
0.4
0.6
0.8
1
1.2
0 4 8 12 16 20
XO
xid
ati
on
Time (Min)
100% CH4
50%
20%
T=850 oC
Oxidation’s conversion is for higher Ch4
concentration during reduction
CFB8 - REM, 5/3/2005
Rate Analysis (Cu-base Oxidation)
y = 6465.1x - 7.5157R² = 0.9582
-3
-2.5
-2
-1.5
-1
-0.5
0
0.0008 0.00085 0.0009 0.00095 0.001
ln(k
) (m
in-1
)
1/T (K-1)
E=53.75 kJ/mole
y = 2483x - 3.2434
-3
-2.5
-2
-1.5
-1
-0.5
0
0.0008 0.00085 0.0009 0.00095 0.001
ln(k
) (m
in-1
)
1/T (K-1)
E=20.64 kJ/mole
50% CH4 reduction20% CH4 reduction
CFB8 - REM, 5/3/2005
Fuel Reactor Analysis
For reaction aA(g) +bB(s)=cR(g)+dS(s)
4 2 24 4 2CH CuO Cu CO H O
Gas phase mass transport4CH
g
dmaR
dy
Where “a” is contact area between solid and gas per
unit volume of bed
6(1 )
p
ad
Solid phase mass transport
,(1 )
CuO mix
g
dmabR
dy
"0.6*( )1
3
oxyr o s oAA
s s CuO
MWm m Rdm dX dXR
A dt A dt MW dt
CFB8 - REM, 5/3/2005
Summary
Completed kinetics rate CuO/bentonite sorbent{1}
-Rate of reaction increases as temperature increased.
Analyzed kinetics rate Fe-based/bentonite sorbent
CFB8 - REM, 5/3/2005
Publications
1. Esmail R. Monazam1,2, Ranjani Siriwardane, Lawrence J. Shadle, George Richard,
Hanjing Tian2 , David E. Huckaby, and Stephen Carpenter2 “Kinetics of the chemical
looping reduction of CuO/bentonite by methane (CH4) “ submitted for internal review
CFB8 - REM, 5/3/2005
Performance and Kinetics of a Solid Amine Sorbent for Carbon Dioxide Removal
Esmail R. Monazam+, Lawrence J. Shadle, Ranjani Siriwardane, Daniel
Fauth, James S. Hoffman, McMahan L. Gray, and Henry Pennline
National Energy Technology Laboratory+REM Engineering Services, PLLC
Morgantown, West Virginia
CFB8 - REM, 5/3/2005
Objective
To characterize a solid supported amine CO2 sorbent (Amine/Bentonite ,
and PEI/Silica) developed at the National Energy Technology Laboratory
(NETL).
- Investigate the kinetics of the CO2 uptake from
experimental data using thermo-gravimetric analyzer (TGA)
and volumetric adsorption apparatus on selected solid
supported amine.
Thermo-gravimetric Analysis (TGA)–Used to record the change in mass of ~60 mg samples of
(amine/bentonite) over time
Volumetric Adsorption Apparatus- equilibrium absorption - Pressure measurements before and after the exposure of the sample
chamber to CO2
CFB8 - REM, 5/3/2005
Reaction of CO2 + Amine (R1R2NH),
Formation of zwitterion;
1 1
1
,
1 2 2 1 2 ( )K k
kR R NH CO R R NH COO zwitterion
Proton removal step of the zwitterion by amine;
2 2
2
,
1 2 1 2 1 2 1 2 2( )K k
kR R NH COO R R NH R R NCOO carbamate R R NH
(1)
(2)
Combining Eqs (1) and (2) resulted;
3 1 2
1 2
1 2
1 2 2 1 2 2 1 22K K K
k k
k k
R R NH CO R R NH R R NCOO
(3)
(R1=CH2CH2OH=C2H4OH) R2=H for MEA, R2=R1 for DEA
CFB8 - REM, 5/3/2005
Reaction of CO2 + Amine (R1R2NH),
2 , 1 2 1 2 1[ ][ ] [ ]CO zwitr k CO R R NH k Z
2
1 2 2 2
1
1 1 2 1 2
1e
CO
R R NH CO COr
k
k k k R R NH
1
1 1 2 1 2
1
1
[ ]
appkk
k k k R R NH
2 1 2 2 2CO app er k R R NH CO CO
kapp=apparent rate coefficient for the reaction
between CO2 and amine (m3/kmol.s)
Overall reaction rate (kmole/m3.s)
CFB8 - REM, 5/3/2005
Effect of reaction temperature on
Amine/bentonite particle and CO2
reaction
0
0.2
0.4
0.6
0.8
1
0 1 2 3 4
Time (min)
X=
(m-m
o)/
(mf-m
o)
30
40
50
60
80
Temperature (oC)
Mean particle size : 70 m
Particle B
0
20
40
60
80
100
120
0 50 100 150 200 250 300
Time (min)
Tem
pera
ture
(oC
)
56
57
58
59
60
61
62
63
Mass (
mg)
Introduction
of CO2
Typical temperature and mass
measurements during TGA
experiment
Experimental data:Amine/bentonite (TGA)
Rate of reaction increases as
temperature increases
CFB8 - REM, 5/3/2005
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.5 1 1.5 2 2.5 3
Time (min)
Co
nve
rsio
n,X
TGA Exp.
Curve fit (Eq. 9)
Mean particle size:70 m
Temperature:40 oC
Particle B
Curve fitting to experimental data to obtain k and n
( ( ) )
( )
o
f o
m t mX
m m
(1 )ndXk X
dt1
11 1 (1 ) nX kt n
T (K) k (s-1
) n
303 0.014 0.88
308 0.016 0.88
313 0.022 1.01
318 0.019 0.99
323 0.019 1.05
333 0.023 1.17
353 0.035 1.48
363 0.037 1.41-5
-4.5
-4
-3.5
-3
0.0025 0.0027 0.0029 0.0031 0.0033 0.0035
1/T (0K
-1)
ln (
k)
1687.6ln 1.37k
T
CFB8 - REM, 5/3/2005
Volumetric Adsorption data- Adsorption Equilibrium
2
2
2
max( )CO
eq CO
CO
dK
dC
2
2 max 1 eq COK C
CO e
Experimental variation of CO2 loading with equilibrium partial
pressureCurve fitting of experimental data to obtain Keq
CFB8 - REM, 5/3/2005
max
2
max
1
1 2eqeq
COK
max 1.923 .0048T
(Alatiqi et al., 1994)
Variations of CO2 concentration with CO2 loading
y = -0.0048x + 1.9272R² = 0.8062
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
300 320 340 360 380 400
ma
x
T (oK)
Equil. Exp.
TGA
CFB8 - REM, 5/3/2005
1batX e
a~scale parameter
b~shape parameter
Weibull distribution function
Experimental data:PEI/silica, 196C (TGA)
Effect of reaction temperature on PEI/silica particle with CO2 reaction
Rate of reaction decreases as temperature
increased.
Typical temperature and mass measurements
during TGA experiment (10%CO2, 40 oC)
CFB8 - REM, 5/3/2005
0
0.2
0.4
0.6
0.8
1
0.0 0.5 1.0 1.5 2.0
Co
nv
ers
ion
(X
)
Time (min)
T=40 C
T=60 C
T=80 C
T=100 C
T=110 C
Effect of reaction temperature on immobilized PEI sorbent
particle and CO2 reaction using 100% CO2
( ) o
f o
m t mX
m m
(1 )batX e
0
0.4
0.8
1.2
1.6
2
0.0 0.5 1.0 1.5 2.0
dX
/dt
Time (min)
T=40 C
T=60 C
T=80 C
T=100 C
T=110 C
Effect of temperature on reaction rate
2
662
0.6930.42 (1 ) ln(1 )TCO
dXe y X X
dt
For b=2
Rate Analysis
CFB8 - REM, 5/3/2005
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0.0E+00 1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05
(mo
le C
O2/m
ole
am
ine
)
[CCO2] mol/CC
40 oC
60
80
100
2 2ln( ) ln( )e eq CO eq CO
RTK C B K C
H
2ln( ) ln( )e eq COB K B C
Temkin’s model assumes that the heat of adsorption of all
molecules in the layer would decrease linearly with coverage
0.0
1.0
2.0
3.0
4.0
-14 -13 -12 -11 -10
(mo
le C
O2/m
ole
am
ine
)
Ln[CCO2] mol/CC
40 oC
60
100
80
Adsorption Equilibrium-TGA data
CFB8 - REM, 5/3/2005
Summary
Completed kinetics rate Amine/bentonite sorbent (1, 2)
-Rate of reaction increases as temperature increased.
Completed kinetics rate PEI/silica sorbent (3)
-Rate of reaction appear to be faster at lower temperatures (apparent negative
activation energy)
CFB8 - REM, 5/3/2005
Publications
Esmail R. Monazam, Lawrence J. Shadle, and Ranjani Siriwardane “Equilibrium and
Absorption Kinetics of Carbon Dioxide by Solid Supported Amine Sorbent “AIChE J. 2011,
DOI 10.1002,
Esmail R. Monazam, Lawrence J. Shadle, and Ranjani Siriwardane “Performance and Kinetics
of a Solid Amine Sorbent for Carbon Dioxide Removal” Accepted for publication Ind. & Eng.
Chem. Res. (July 2011) ie-2011-01214q
Esmail R. Monazam, Lawrence J. Shadle, Daniel Fauth, James S. Hoffman, McMahan L. Gray,
and Henry Pennline “Kinetics Analysis of Carbon Dioxide Capture on Immobilized Amine on
Meso-Porous Silica” AIChE J. 2011, submitted.