1. Huazhong University of Science and Technology，China
Co-production of hydrogen and carbon nanotubes from catalytic pyrolysis of waste plastics on Ni-Fe bimetallic catalyst
Dingding Yao a, Haiping Yang a, Yeshui Zhang b, Mohamad A. Nahil b, Chunfei Wu c , Daqian Wang a,
Hanping Chen a, Paul T. Williams b
Good afternoon to everyone. Today I would like to present
a Huazhong University of Science and Technology, Wuhan, , China
b Energy Research Institute, The University of Leeds, Leeds, LS2 9JT, UK
c School of Engineering, The University of Hull, Hull, HU6 7RX, UK
PYRO 2016, MAY 11TH, 2016

2. Outline Background about plastics waste Materials and methods
Huazhong University of Science and Technology
Background about plastics waste
Materials and methods
Mass balance and gas production
Morphologies and quality of solid product
Here are the outline for my presentation. I have divide the presentation in 4 parts, I will start with very brief introduction on this studies where I will explain the most relevant background of these research, Next I will give some explanations about the experimental equipment, the main results, the conclusion of my finding
Summary 2

3. Plastics production 3 Huazhong University of Science and Technology
For more than 100 years, plastics materials have been key enablers for innovation (healthcare, enenrgy generation, construction, electronics,packing) and have contributed to the development and progess of society. 3

4. Plastics production World and European plastics production 2002-2013 4
Huazhong University of Science and Technology
For more than 100 years, plastics materials have been key enablers for innovation (healthcare, enenrgy generation, construction, electronics,packing) and have contributed to the development and progess of society.
Generally, Plastics production grows globally year by year, in EU, the production stablized in 2013 after increase may come from the fast-growing developing countries like China
World and European plastics production
References: Plastics - the Facts 2014/2015, PlasticsEurope 4

5. Plastics production
Huazhong University of Science and Technology
China ranks first in the global plastics materials production
China ranks first in the global plastics materials production
2013 World production of plastic materials 5

6. Plastics waste in China
Huazhong University of Science and Technology
《废塑料综合利用行业规范条件》
Plastics waste in China
References: 《废塑料综合利用行业规范条件》,Ministry of Industry and Information Technology, China, 2016. 6

7. Plastics waste management
Huazhong University of Science and Technology
Plastics Waste
Traditional way
Burning
Landfill
How to
manage
Greenhouse
 effect
Dioxin
Used tires
Land 
occupation
With the huge plastics production,it generates the
So tackle thses wastes in a renewable way, that is, make full use ….convert them to high value products, wil be a promising technology
Renewable way
Make full use of high C, H content in waste
Clean
energy
Other high C，H
content wastes 7

8. Gasification of plastics waste
Huazhong University of Science and Technology
Heat
Gases
Liquid
(tar, oil)
Solid (char)
Coke deposition
On catalyst
Pyrolysis
Gas-phase reactions
(cracking, shift
combustion,)
Reforming H2
CH4
Plastics
Drying
Gas-solid
Interaction
Modification
CNTs growth
Fe, Co, Ni based catalyst
 amorphous carbon to ordered CNTs without much loss in catalyst reactivity
bi-/trimetallic are relatively cheap, better catalytic performances , higher stability
smaller metal particle size and synergetic effect between Ni and Co particles.
Co-production H2 and CNTs from catalytic pyrolysis of plastics waste
References: [1] Yao et al Internal. Hydrogen Energy, 39(27): 14642–14652
[2] Wu et al.2014.Environ. Sci. Technol., 48(1): 819–826 8

9. Aim Fe-Cu Fe Ni Bimetallic catalyst Ni-Co Ni-Fe
Huazhong University of Science and Technology
Co-production H2 and CNTs from catalytic pyrolysis of plastics waste
Fe-Cu Fe Ni
Bimetallic catalyst
Relatively cheap
Synergetic effect
Higher stability
Better catalytic performances
Smaller metal particle size
Ni-Fe
Ni-Co
there are limited data about using the combination of both metals for CNTs and hydrogen productions from waste plastics.
How about Ni-Fe bimetallic catalyst?
Effect of mixture of Ni and Fe with different molar ratios on hydrogen and CNTs productions from waste plastics
References: [1] Shen et al Applied Catalysis B: Environmental, 181:
[2] Wei et al International Journal of Hydrogen Energy, 40(46): 9

10. Outline Background about plastics waste Materials and methods
Huazhong University of Science and Technology
Background about plastics waste
Materials and methods
Mass balance and gas production
Morphologies and quality of solid product
Here are the outline for my presentation. I have divide the presentation in 4 parts, I will start with very brief introduction on this studies where I will explain the most relevant background of these research, Next I will give some explanations about the experimental equipment, the main results, the conclusion of my finding
Summary 10

11. Schematic diagram of the pyrolysis-catalysis of plastics
Materials and methods
Huazhong University of Science and Technology
Feedstock:
Mixed plastics: HDPE:LDPE:PP:PS = 4:3.5:2:0.5
Catalyst: Ni-Fe/Al2O3, impregnation
Ni:Fe molar ratio=1:3, 1:2, 1:1, 2:1, 3:1
NFxy means Ni:Fe=x:y
Materials
Element C H O
Content, wt.%
84.51
13.85
1.63
Plastics: g
Carrier gas: Ar (110mL/min, 99.99%)
Temperature: T1 500 ℃
T2 800 ℃
Catalyst: g
Operation parameters
However, there are limited data about using the combination of both metals for CNTs and hydrogen productions from waste plastics. In this work, a two stage fixed bed reaction system was used to obtain the effect of mixture of Ni and Fe with different molar ratios on hydrogen and CNTs productions.
We choose some kinds of plastics and mix them together, the proportion of each kind is like this, which is a
typical waste plastics composition in China
Schematic diagram of the pyrolysis-catalysis of plastics 11

12. Materials and methods Methodology Gas chromatography (GC);
Huazhong University of Science and Technology
Methodology
Gas chromatography (GC);
Mass spectroscopy (MS);
Temperature programmed oxidation (TPO);
Scanning electron microscopy (SEM);
Transmission electron microscopy (TEM);
Raman spectroscopy.
Characterize Morphology and quality of carbon deposition 12

13. Outline Background about plastics waste Materials and methods
Huazhong University of Science and Technology
Background about plastics waste
Materials and methods
Mass balance and gas production
Morphologies and quality of solid product
Then I will talk about the main results
Summary 13

14. Gas emission None catalyst Ni : Fe=1:3 Ni : Fe=1:2 Ni : Fe=1:1
Huazhong University of Science and Technology
None catalyst
Ni : Fe=1:3
Ni : Fe=1:2
Ni : Fe=1:1
Ni : Fe=2:1
Ni : Fe=3:1
Syngas from pyrolysis of plastic wastes mainly consist of CH4, CO, H2 and C2H2. When Ni/Fe catalysts were applied, more hydrogen and CH4 were produced. More O containing gas like CO and CO2 were formed at the beginning of the reaction. Hydrogen and CH4 reached maximum value in the range of 400 to 450 °C. It can be seen NF12 and NF13 have higher H2 selectivity than other catalysts. Gas emission are similar at higher ratio of Ni to Fe, which is consistent with Table
both
Ni:Fe=1:2 and Ni:Fe=1:3 have higher H2 selectivity. 14

15. Mass balance and gas production
Huazhong University of Science and Technology
Mass balance and gas production with different Ni-Fe catalyst
None
NF13
NF12
NF11
NF21
NF31
H2 yield (%)
11.42
61.17
56.15
49.85
48.92
52.30
Gas yield (wt.%)
50.51
39.48
38.01
43.24
43.87
39.64
Carbon deposition (wt.%)
2.2
50.9
49.9
45.8
45.1
Mass balance (%)
80.51
99.18
101.41
96.14
98.87
95.74
Gas composition (vol.%) H2
24.74
73.93
73.59
64.81
63.84
69.98 CO
2.98
3.90
3.74
4.19
3.76
4.37
CH4
49.36
16.77
15.12
26.40
27.16
19.15
CO2
0.67
0.62
0.64
0.77
0.65
0.76
C2H4
19.81
3.43
4.88
3.12
3.60
4.15
C2H6
2.24
1.30
1.97
0.63
0.92
1.56
C2H2
0.20
0.04
0.05
0.08
0.07 ／
For the yield, more than 40 to 50 of H2 yield are increased when using catalyst
Gas composition also changes a lot. CH4 takes nearly 50 per in the pyrolysis gases, but it decrease greatly and up to 70 perc of H2 are generated with catalyst.
The carbon deposition yield are about
Both the H2 concentration and yield reached maximum values of vol.% and %, respectively, in the presence of NiFe13 catalyst. 15

16. Outline Background about plastics waste Materials and methods
Huazhong University of Science and Technology
Background about plastics waste
Materials and methods
Mass balance and gas production
Morphologies and quality of solid product
Here are the outline for my presentation. I have divide the presentation in 4 parts, I will start with very brief introduction on this studies where I will explain the most relevant background of these research, Next I will give some explanations about the experimental equipment, the main results, the conclusion of my finding
Summary 16

17. Morphologies of reacted catalysts
Huazhong University of Science and Technology
NF13
NF12
NF11
NF21
NF31
the deposits on the catalyst surface are predominantly mainly filamentous type carbons. There was a dense covering of these carbons, as we expect, fairly long and thin 17

18. Crystal size corresponding to main peaks of each catalyst (D, nm)
XRD analysis of reacted catalysts
Huazhong University of Science and Technology
Scherrer Equation:
Crystal size corresponding to main peaks of each catalyst (D, nm)
Catalyst
Main peak, 2θ(°)
33.2
35.9
37.1
NF13
40.8
35.0 —
NF12
43.1
19.5
NF11
18.1
NF21
19.1
10.5
NF31
19.8
The diameter of carbon nanotubes was associated with the crystal size of catalyst. 18

19. Morphologies of reacted catalysts
Huazhong University of Science and Technology
NF13
NF12
NF11
Tip-growth mechanism of CNTs formation
NF21
NF31
From TEM, as the metal particle is found in nanotubes, which was far from catalyst support, the tip-growth mechanism of CNTs formation was deduced during the catalysis-pyrolysis of plastic wastes in the presence of Ni-Fe catalyst. 19

20. TPO results of reacted catalysts
Huazhong University of Science and Technology
The carbon deposited on catalyst became less reactive when Ni to Fe molar ratio increased, as the oxidation peak from DTG analysis moved to higher temperature with Ni content increased. It indicated Ni composition in catalyst enhanced the thermal stability of formed carbon.
TPO results shows that Ni composition in catalyst enhanced the thermal stability of formed carbon.
Carbon deposited on catalyst became less reactive when Ni to Fe molar ratio increased, indicating Ni composition in catalyst enhanced the thermal stability of formed carbon. 20

21. Raman analysis of coke deposition
Huazhong University of Science and Technology
D: defects within the graphitic lattice
G: Graphitic carbon
G’: Purity of CNTs
Raman spectroscopy is often used to characterise CNTs。 peak at 1589 cm−1 Wavelength corresponds to the G peak associated with graphitic carbon
 the peak at 1348 cm−1 corresponds with the D peak indicate defects within the graphitic lattice. G’  indicating the purity of CNTs.
based on these two ratios, we can see how ordered and graphitic they are,and then evaluate the quality of the carbon nanotubes.
…carbon deposition at this higher Ni to Fe ratio has a higher purity and ordered carbon nanotubes.
Despite there being less carbon deposition, the quality of the filamentous carbon at higher Ni to Fe ratio is higher with more ordered carbon walls.
CNTs produced at higher Ni to Fe ratio have higher purity. 21

22. Comparison with other reports
Huazhong University of Science and Technology
Comparison of gas yield and carbon deposition between this work and relevant references
Material
Catalyst
H yield (g/100g sample)
Carbon (g/100g sample)
ID/IG
Source
Mixed plastics
Ni-Fe/Al2O3
6.8~7.3 46
0.55~0.71
This work
LDPE
Ni/Al2O3
3.3 52
0.588
[1] PP 25
0.84 PS
2.7
0.93
Fe/Al2O3
3.9 27
0.51
[2]
Waste tires
1.5 38
0.89
[3]
3.6 39
0.88
Motor oil container
Ni-Mn-Al
12.2
0.9
[4]
At last, we make a comparision between our work and relevant references. Shown in this table. Bimetallic catalysts generate
References: [1] Acomb et al.2014.Applied Catalysis B: Environmental,147:571–584.
[2] Acomb et al.2015.Journal of Analytical and Applied Pyrolysis,113:231–238.
[3] Zhang et al.2015.Energy Fuels, 29 (5): 3328–3334
[4] Wu et al.2014.Environ. Sci. Technol., 48(1): 819–826. 22

23. Summary Ni:Fe=1:3 catalyst has higher H2 concentration and yield.
Huazhong University of Science and Technology
Ni:Fe=1:3 catalyst has higher H2 concentration and yield.
Catalyst with higher Ni to Fe ratio produced more ordered and higher purity carbon nanotubes.
Ni addition enhanced the thermal stability of formed carbon.
The tip-growth mechanism of CNTs formation was concluded.
800oC,Fe-Ni H2
Carbon Nanotubes
500oC
Cracking
Dehydrogen
Both hydrogen and carbon yield reach maximum with NF13 catalyst. 23

24. Acknowledgment Pyro2016 organizer
Huazhong University of Science and Technology
Pyro2016 organizer
Co-workers: Paul T. Williams, Chunfei Wu, Yeshui Zhang,
Mohamad A. Nahil, Haiping Yang
The National Natural Science Foundation of China
State Key Laboratory of Science and Technology
Both hydrogen and carbon yield reach maximum with NF13 catalyst. 24

25. Thanks for your attention!