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MODEL FREE KINETICS OF MALAYSIAN COAL AND WASTE PLASTICS
BLENDS DURING CO-PYROLYSIS PROCESS
Nurfarahima Binti Ibrahim and Sharmeela Matali.
Faculty of Chemical Engineering, Universiti Teknologi Mara 40450 Shah Alam, Selangor.
Model free kinetics algorithms was applied to determine
conversion, iso-conversion and activation energy during
co-pyrolysis of high density polyethylene (HDPE) and coal.
The kinetics data were be obtained from TGA data at
different heating rate and model fitting methods. Thermal
behavior of the polyethylene and coal material was be
investigated by knowing thermal degradation kinetics.
Thermal degradation of polymer is a more complex
reaction, thus the reliable model of kinetics models is very
important to get a best results. To estimate the kinetics
data of degradation, the Kissinger’s and Ozawa-Flynn
Wall model free kinetics method were applied. The data
have been obtained via thermogravimetry analysis during
co-pyrolysis of Silantek coal and waste plastics (HDPE)
blends at nitrogen atmosphere, under dynamic conditions
at different heating rate of 10, 20 and 40oC/min. The
kinetics parameters, activation energy (Ea), and pre-
exponential factors (A) of the blends were calculated using
these model equations by function of peak temperature
and heating rate. Therefore, from the calculated results
showed that the activation energy of the coal/HDPE
blends is 238.128 kJ/mol and 250.822 kJ/mol respectively
between temperature range of 300-600oC, and it can be
characterized by first order reaction. DTG curves
coal/HDPE blends are found to be overlapping and due to
possible chemical interaction between these material [1].
1. Sample preparation
Results Results
Conclusion
Recommendation
Acknowledgement
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Figure 1: Sample Preparation
 To determine the best model free kinetics to represent
experimental data.
 Application of free model kinetics for the co-pyrolysis
process.
2. Proximate Analysis & Thermal Degradation
Kinetics analysis
Figure 2: Thermogravimetric Analyzer (Mettler Toleda/TGA/SDRA51e)
3. Calorific Value Analysis
Mass ratio of blending will affected the calorific value
were increasing amount of mass ratio HDPE reduces
the calorific values of blended samples.
The low degree of branching and required higher energy
to break the stronger intermolecular forces in the
polymeric chain of HDPE [2].
4. Thermogravimetric Profile (TG)
 The weight loss during the pyrolysis process in the
temperature range 300-600°C due mainly to gases
emission gases emission with a mass loss between
60wt%.
 The decomposition curves of the blends are
overlapped which may be due to interactions of solid-
solid and solid-gas [1] .
3. Ultimate Analysis
The model free kinetics study is one of the methods to
obtain the activation energy and pre-exponential factors
from the co-pyrolysis study via thermogravimetric analysis.
Under the pyrolysis conditions, the material decomposition
start to degrade at approximately 300°C with progressively
and rapidly up to 450°C to 600°C.
8. Ozawa-Flynn Wall (OFW) Model Kinetics
4. Model Free Kinetics Methods
Figure 3:Thermo Finnigan Flashed 1112 analyser
 If the percentage of volatile matter increasing, the
percentage of char yield will decrease.
 At range weight ratio 40wt% to 60wt%, the curves of
char yield and volatile matter intersect, assumed that
the char yield produced is inversely proportional to the
volatile matter contents blended sample.
Table 3 : Thermal decomposition of Silantek coal/HDPE blends at different heating rates.
lgβ= log AE/βR -2.315 - 0.4567 E/RT (Eq2)
References
Thank you to my Research Project supervisor, Mdm
Sharmeela Matali and Universiti Teknologi Mara (UiTM).
1. Z. Mikulová and J. F. , Marek Večeř. Study Of Pyrolysisis Of Polymers And
Coal And Co-Pyrolysis Of Their Blends, Kinetics Of The Process. Trans. VŠB –
Tech. Univ. Ostrava, Mech. Ser., vol. LVIII, no. 1, pp. 147–155, 2012.
2. Sharmeela Matali, Mohd Ridzuan Mohatar. Thermogravimetric Analysis of the
Pyrolysis Characteristics on Sarawak Silantek Coal, Waste Tyre, Waste HDPE
and their blends Shah Alam : International Journal of Chemical Engineering,
2015.
Cutting → Drying → Grinding → Sieving
 Kissinger’s Method.
 Ozawa-Flynn Wall Method.
Chemical Element Silantek Coal (wt%) HDPE (wt%)
Carbon 74.186 80.58
Hydrogen 4.350 8.406
Nitrogen 1.454 9.359
Sulphur 0.010 0.526
Oxygen 20.00 1.129
Table 1: Proximate Analysis of Silantek Coal and Waste Plastic HDPE
Figure 4: The Calorific Value of the HDPE, Silantek Coal and their Blends .
0
2
4
6
8
10
12
14
16
18
20
22
0 70 140 210 280 350 420 490 560 630 700 770 840 910 980
WeightRatio(mg)
Temperature (°C)
Thermogravimetric Profile (TG)
HR40
HR20
HR10
Figure 5: Thermogravimetric (TG) Profile of the Silantek Coal and Waste HDPE blends at different heating
rates at weight ratio blends of 40% Silantek Coal.
5. Derivatives Thermogravimetric Profile (DTG)
 The peak temperature for this thermal event for heating
rate 10°C/min is 479°C with peak height, R of 3.05
mg/min.
 The peak temperature for this thermal event for heating
rate 20°C/min is 497°C with peak height, R of 6.210
mg/min. .
 The peak temperature for this thermal event for heating
rate heating rate 40°C/min is 504°C with peak height, R
of 10.34 mg/min.
-11
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-8
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-6
-5
-4
-3
-2
-1
0
1
0 70 140 210 280 350 420 490 560 630 700 770 840 910 980
weightratio(mg/min)
Temperature (°C)
Derivatives Thermogravimetric Profile (DTG)
HR40
HR20
HR10
Figure 6: Derivatives Thermogravimetric (TG) Profile of the Silantek Coal and Waste HDPE blends at
different heating rates at weight ratio blends of 40% Silantek Coal.
6. Thermal Degradation
HR Blend TEP 1 R TEP 2 R CY(%) VM(%)
°C/min SC:HDPE Tmax mg/min Tmax mg/min
10 100:0 61.15 0.21 452.10 0.20 45.22 54.78
80:20 60.95 0.21 475.23 0.90 53.30 46.70
60:40 58.35 0.14 482.71 2.13 46.29 53.71
40:60 51.72 0.11 478.88 3.05 42.31 57.69
20:80 49.69 0.01 484.37 4.71 20.21 79.79
0:100 452.09 0.94 44.05 55.95
20 100:0 79.39 0.43 445.52 0.59 49.89 50.11
80:20 497.60 2.60 68.98 31.02
60:40 493.33 2.98 60.78 39.22
40:60 497.39 6.21 37.40 62.60
20:80 495.87 8.08 29.61 70.39
0:100 493.73 9.28 22.09 77.91
40 100:0 441.92 0.91 51.97 48.03
80:20 85.39 0.89 493.83 3.54 59.67 40.34
60:40 85.06 0.85 503.07 6.49 46.74 53.26
40:60 79.28 0.65 503.55 10.34 34.81 65.19
20:80 76.70 0.26 504.23 14.19 30.86 69.14
0:100 101.91 0.11 502.98 19.12 12.40 87.6
Abstract
Results
1. Proximate Analysis
Aspect Silantek Coal (wt%) HDPE (wt%)
Volatile Matter 48.36 87.51
Fixed Carbon 45.22 0
Ash 6.42 12.49
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
100.0% 80.0% 60.0% 40.0% 20.0% 0.0%
Weightrartio%
Weight Ratio % (COAL:HDPE)
Thermal Degradation of Char Yield and Volatile Matter
CR40
CR20
CR10
VM40
VM20
VM10
7. Kissinger’s Model Kinetics.
ln(β/Tm²) = lnAR/E – E/RTm (Eq1)
Where: β = heating rate
Tm = maximum temperature
A =pre-exponential factor
R = rate constant
Ratio Kinetics Data’s
SC:HDPE Slope Intercept Ea(kJ/mol) A(sˉ¹)
100:0 -32191.069 30.949 267.646 8.88E+17
80:20 -39654.125 37.920 329.696 1.17E+21
60:40 -37455.966 34.510 311.420 3.64E+19
40:60 -28640.793 23.002 238.128 2.80E+14
20:80 -39160.646 36.622 325.593 3.15E+20
0:100 -67539.227 73.400 561.541 5.09E+36
Table 4: The kinetic data of Kissinger’s Method.
Blend Kinetic Parameter
% Slope Intercept Ea(kJ/mol) A(sˉ¹)
100 -33612.668 30.949 279.466 9.275E+17
80 -41168.131 37.920 342.284 1.211E+21
60 -38987.946 34.510 324.157 3.787E+19
40 -30167.521 23.002 250.822 2.946E+14
20 -40694.531 36.622 338.347 3.269E+20
0 -69080.905 73.400 574.359 5.208E+36
Table 5: The kinetic data of Ozawa Flynn Wall Method.
267.646
297.222
311.420
238.128
325.593
561.541
279.466
308.988
324.157
250.822
338.347
574.359
200.0
250.0
300.0
350.0
400.0
450.0
500.0
550.0
600.0
0.0% 20.0% 40.0% 60.0% 80.0% 100.0%
ActivationEnergy()kJ/mol
Blend Ratio
Model Kinetic of Co-pyrolysis
Kissinger
OFW
Figure 10: : Comparision of Model Free Kinetics during co-pyrolysis of Silantek Coal and waste plastic
HDPE blends
Model
kinetic
Blends ratio
100:0 80:20 60:40 40:60 20:80 0:100
Kissinger Ea (kJ/mol) 267.6462 297.2219 311.4201 238.1281 325.5934 561.5414
A(sˉ¹) 8.88E+17 1.17E+21 3.64E+19 2.8E+14 3.15E+20 5.09E+36
R² 0.5035 0.959 0.9996 0.9115 0.9896 0.8182
Ozawa-Fynn
Wall
Ea (kJ/mol) 279.4658 308.9883 324.1575 250.8218 338.3465 574.3594
A(sˉ¹) 9.28E+17 1.21E+21 3.79E+19 2.95E+14 3.27E+20 5.21E+36
R² 0.5251 0.9627 0.9997 0.9195 0.9904 0.8248
Table 6 : Comparision of Model Free Kinetics data
2. Ultimate Analysis
Table 2: Ultimate Analysis of Silantek Coal and Waste Plastic HDPE
Figure 7: Thermal Degradation of Char Yield and Volatile Matter
 The lowest Ea is obtained weight ratio of 40:60 and
corresponding R2 value be represent the best fit model
for experimental, calculated were 0.9115 ofr
Kissinger’s model and 0.9195 for OZW model which
are considered acceptable and fits well with there two
models.
Used the various type of the waste material blends with
natural sources and continues for other heating rate for
further study of model kinetics.
Methodology
Objectives
 The lowest activation energy (Ea ) was obtained at
weight ratio of 40:60 with 238 kJ/mol and pre-
exponential factor is 2.8x10¹⁴sˉ¹ were the best blended
ratio of the blended sample.
 Form the table, the activation energy increasing from
the pure Silantek Coal until purely HDPE which is
268kJ/mol ad 561kJ/mol respectively.
 The lowest activation energy (Ea) value was obtained
at weight ratio of 40:60 with 251 kJ/mol and pre-
exponential factors is 2.95x10¹⁴sˉ¹ were the best
blended ratio of the blended sample.
 The activation energy (Ea) value increasing from the
pure Silantek Coal until purely HDPE which is 279
kJ/mol ad 574 kJ/mol respectively.