5-7 OCTOBERISFR2011

59

TOLEDO (SPAIN)PYROLYSIS OF A WASTE FRACTION OF ACRYLONITRILE BUTADIENE STYRENE(ABS) CONTAINING BROMINATED FLAME RETARDANTS IN A FLUIDIZED BED
REACTOR: EFFECT OF VARIOUS Ca-BASED ADDITIVES (CaO, Ca(OH)2 AND
OYSTER SHELLS) ON THE PYROLYSIS OIL CHARACTERISTICS
Su-Hwa Jung, Min-Hwan Cho, and Joo-Sik Kim
Faculty of Energy and Environmental System Engineering, University of Seoul, 90 Jeonnong-Dorhng,
Donggaemun-Gu, Seoul 130-743, Republic of Koreae-mail: pysoo80@gmail.com

Abstract
A waste fraction of acrylonitrile butadiene styrene (ABS) containing brominated flame retardant and antimony trioxide(Sb2O3) as synergist was pyrolyzed in a bench-scale plant equipped with a fluidized bed and char separation system.
Experiments were carried out to find out the effect of the three additives (CaO, Ca(OH)2, oyster shells) on the characteristicsof pyrolysis oil. The oil and gas fraction were quantitatively and qualitatively analyzed by GC-FID/TCD and a GC-MS and thecontent of bromine and chlorine in the oil fraction was determined by EPA 5050 method. The antimony content of pyrolysis
products was analyzed by an ICP-AES. Analysis of the pyrolysis oil obtained in the absence of additive that was mainlycomposed of toluene, ethylbenzene, styrene, cumene, α-methylstyrene, phenol, benzenebutanenitrile and (1-chloroethyl)benzene. The contents of bromine and chlorine in the pyrolysis oil produced at 484 °C without any additive were about 2000
and 2700 ppm, respectively. The bromine and chlorine contents of the pyrolysis oil produced in the presence of Ca(OH)2,decreased down to 500 and 600 ppm, respectively.

Keyword: Pyrolysis, Fluidized bed, Acrylonitrile butadiene styrene, Halogen compounds, Additive

1. Introduction
The management and treatment of waste electrical andelectronic waste (WEEE), which is generating about 50
million tons worldwide, is becoming a major topic [1].
WEEE is continuously increasing and consequently gives
rise to environmental problems. Among the WEEE
materials, plastics are difficult to be recycled mainly due
to the flame retardants in them. According to the EU
directive, however, the fraction of major plastics of WEEE
demands for recovery [2]. To convert WEEE plastics
containing brominated flame retardants into either fuel oil
or useful chemicals, pyrolysis, which is one of thepromising techniques, has been widely investigated bymany researchers. Pyrolysis of ABS containing
brominated flame retardant has been mostly carried out
in the fixed bed reactor, and the research using a
fluidized bed reactor was rare.
In this work, a waste fraction of acrylonitrile butadienestyrene containing flame retardants was pyrolyzed in apyrolysis plant equipped with a fluidized bed and charseparation system. The goal of this study was to find out
the influence of various additives (CaO, Ca(OH)2, oystershells) on the characteristics of pyrolysis oil

2. Materials and Methods
Material. Waste acrylonitrile butadiene styrene
containing brominated flame retardant was provided by
local recycling center in Korea. First, the feed materialinteriores libro.indd 59

was grounded and sieved to reduce the particle size witha diameter of 2~3.35 mm. It contained brominated flame
retardants with synergist (Sb2O3). The bromine, chlorine
and antimony content of feed material were about 3.2,0.4 and 3.8 wt.%, respectively. The additives (CaO,Ca(OH)2, and oyster shells) were powder type and weremixed the feed material before pyrolysis experiment.
Pyrolysis plant and procedure. Fig.1 shows thepyrolysis plant.

Fig. 1 Pyrolysis plant
It consisted mainly of feeding system, fluidized bedreactor, char separation system, quenching system andproduct gas circulating system. The fluidized bed reactor,

26/9/11 13:12:53

60

6th International Symposium on Feedstock Recycling of Polymeric Materials

which was indirectly heated by electricity, was made of asus-316 steel tube with a height of 390 mm and an innerdiameter of 110 mm. The char separation system wascomposed of a cyclone and a hot ceramic filter, which
could designed to capture the particle size bigger than 10and 2 μm, respectively. The quenching system wasconsisted of one steel condenser which was watercooled at 20 °C and two glass condensers which were
ethanol-cooled at -25 °C. The latter part of the quenchingsystem was electrostatic precipitator that can capture anaerosol phase in the pyrolysis gas. The non-condensable
gas was circulated into the fluidized bed reactor throughthe pre-heater by a compressor.
Reaction conditions. All the experiments were carriedout around 485 °C, with feed rates of around 3.8 g/min
and at fluidizing flow rates of about 64 NL/min. Table 1shows the other experimental parameters.
Table 1. Reaction conditions
ParametersRun
1

Additive
Amount ofadditive (g)

2

0

3

45CaO

൮
1530

678Ca(OH)260

1530

910

Oyster shell
60

153060In each experiment, the input of the feed material was0.3 kg, and 3.8 kg quartz sand was used as the fluidized
bed material. The experiments (R2-R4: CaO, R5-R7:
Ca(OH)2 and R8-R10: oyster shells) were performed tofind out the effect of the calcium based additives on thecharacteristics of the pyrolysis oils. The weight ratio of
the feed material to an additive was 1:0.05 (CaO),1:0.1(Ca(OH)2 ) and 1:0.2 (oyster shells), respectively.
Analysis of products. As pyrolysis products, the threefractions, namely, oil, gas and char were obtained. A
fraction of oil produced from each run was distilled in alaboratory scale apparatus under reduced pressure(210 °C, 13.3 Kpa) to obtain a light fraction. Thisdistillation condition corresponded to the boiling point of
9H-fluorene (boiling point = 295 °C at atmosphericpressure). An analysis of each oil components wasquantitatively and qualitatively analyzed using response
factor of each component. The applied capillary columnof both GC-FID and GC-MS was a HP-5MS and helium
was used as the carrier gas. The bromine content of oil
was analyzed by the EPA 5050 method which was usedby a bomb calorimeter and by an Ion chromatography.
The product gas produced was analyzed with GCs usinga TCD and a FID, and argon was used as a carrier gas.
The applied columns were a Carboxen 1000 for TCD andan HP-plot Al2O3/KCl for FID. The antimony content in
the oil, distillation residue was analyzed by an ICP-AES.

3. Results and Discussion
Organic mass balance. In each experiment, the oil yield
was determined by weighing liquid product. The gas yield
was calculated by multiplying the volume, which wasmeasured the gas meter, and the gas density. The charyield was calculated by difference. After the distillation ofpyrolysis oils, we obtained the light phase, which can beanalyzed by GC-MS, and the viscous phase. In thisstudy, the light phase and the viscous phase wereinteriores libro.indd 60

designated as the oil and the distillation residue,respectively. Finally, the char and the distillation residue
were burnt in furnace to find out the organic content inthem. The organic mass balance of each experiment isshown in Table 2.
Table 2. Total organic mass balance.
Total organic
mass balance(wt.%)
Gas
Oil
BenzeneTolueneEthylbenzene
m/p/o-xylene
StyreneCumeneα-methylstyrene
Phenol
1,3diphenlypropane
N-compounds
Br-compounds
Cl-compounds
OthersNot detected
Char
Distillation
residue

Run
1

2

3

4

5

6

7

8

9

104
74.7
1.1
9.3
18.9
0.2
16
4.2
2.5
3.3

2.7
67
0.2
4.6
6.4
0.3
17
2.4
4.1
4.4

2.3
61.7
0.2
6.1
6.6
0.1
18.8
2.1
5.9
5.7

2.4
49.8
0.1
3.5
3.8
0.1
11.6
1.3
3.5
2.8

2.7
61.3
0.2
4.5
6.3
0.1
11.52.3
4
4

1.6
58.6
0.3
4.6
5.5
0.1
16.2
1.9
4.5
3.8

2.2
53.4
0.2
3.4
3.2
0.1
12
0.9
3.7
1.8

3.5
64.6
0.2
4.3
11.7
0.3
3
3.7
2.4
4.3

3.8
58.9
0.3
4.2
10.8
0.1
10.1
3.5
4.1
6.2

4.3
65.4
0.2
3.8
7.2
0.1
9.4
2.4
4.7
5.8

0.3

1.7

0.3

1.7

0.5

1.6

1.9

3.2

1.2

2.7

9.9
0.4
1.7
4
2.9
8.4

12.9
0.3
1.2
7.5
4.2
18.5

7.1
1.2
0.3
4.9
2.4
26.4

10.30.3
1.1
6
3.7
35.6

11.8
0.2
1.4
9.6
4.9
23.7

10.5
0.4
0.9
5.4
3
26.6

11.9
0.4
1.1
7.3
5.5
35.3

14.1
0.9
1.1
10.5
4.8
20.8

8.4
0.2
1.1
6.3
2.3
25.8

13.8
0.6
11.2
3.6
22.7

12.9

11.7

9.7

12.3

12.3

13.2

9.1

11.2

11.5

7.6

Bromine, chlorine and antimony content in pyrolysis
oil. To reduce the bromine and chlorine content in the oil,calcium-based additives (CaO, Ca(OH)2, and oystershells) were applied the feed material per additive inweight ratios of 1:0.05, 1:0.1 and 1:0.2. Table 3 shows
the amount of bromine and chlorine in the oil with (Run4,Run7 and Run10) and without (Run1) the additives. The
antimony content of oil and distillation residue (Run7)
was 0.001 and 0.002 wt.%, respectively. Most ofantimony was concentrated in the char.
Table 3. Content of Bromine and Chlorine in the oils.
Run1
4
710

Concentration (wt.%)
Bromine
0.2
0.17
0.05
0.2

Chlorine
0.27
0.07
0.06
0.04

4. Conclusions
In this study, the acrylonitrile butadiene styrene withbrominated flame retardant was pyrolyzed in a fluidized
bed reactor equipped with char separation system. To
achieve the dehalogenation of oil, the three calciumbased additives (CaO, Ca(OH)2, and oyster shell) wereapplied by mixing with the feed material. The pyrolysis oil
obtained in the absence of additive consisted mainly of
toluene, ethylbenzene, cumene, α-methylstyrene, phenol,
benzenebutanenitrile and (1-chloroethyl)-benzene. In thepresence of additive, especially Ca(OH) 2, the bromine
and chlorine content in the oil decreased down to 0.05
and 0.06 wt.%, respectively. It was found that the Caadditives were very effective for the dehalogenation ofoil.

References[1] S. Heart. Environmental impacts and use ofbrominated flame retardants in electrical and electronicequipment. Environmentalist 28 (2008) 348–357.
[2] W. J. Hall. and P. T. Williams. Pyrolysis of brominatedfeedstock plastic in a fluidized bed reactor. J. Anal. Appl.
Pyrolysis 77 (2006) 75–82.

26/9/11 13:12:54