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TOLEDO (SPAIN)PYROLYSIS OF CONTAMINATED, POLYOLEFIN REACH PLASTIC WASTES
N. Miskolczi1, N. Borsodi1, A. Angyal1, L. Bartha1 and J. Kohán1
1University of Pannonia, Chemical Engineering and Process Engineering Institute, MOL Department of Hydrocarbon andCoal Processing, Veszprém, Hungary
2 MOL Plc, Százhalombatta, Hungary
e-mail: mnorbert@almos.uni-pannon.huAbstract
Due to the increasing amount of plastics and other wastes, their utilization is in the focus of waste management. The thermal
degradation of wastes plastics is one of the suitable techniques for their recycling. Furthermore by this way wastes could beconverted into valuable hydrocarbons, which are able to use as feed stock materials. The mild pyrolysis of contaminated,polyolefin reach waste plastics was investigated in a tube reactor both absence and presence of catalyst. The effects of theparameters to the properties of products (e.g. gases, naphtha, middle distillates, heavy oil) were discussed. Gases andliquids formed in degradation reactions were analysed mainly by a gas-chromatography, Fourier-transformed infraredspectroscopy, size exclusion chromatography and other standardized methods. Both the yields and structure of products
have been significantly changed with pyrolysis conditions. Plastic wastes could be converted into valuable volatile fractions
with yields of 35-80% depending on the applied parameters. Products had significant content of unsaturated hydrocarbons,
mainly Dolefins. Naphtha and middle distillates had favourable hydrocarbon distribution for fuel-like applications, but theircontaminant levels were high occasionally. The levels of contaminants in different products have been affected by theapplied catalysts.

Keywords: pyrolysis, waste plastics, middle distillates, contaminants, utilization

1. Introduction
Each year more than 300 M tons of plastic wastes are
generated worldwide, therefore the recycling of plastic
wastes and the utilization of products from recycling
technologies are in the focus of waste managements.
Plastic wastes have high so called hidden energy
content, which reusing enormous energy could be saved
with. The R&D activity in the area of waste recycling has
been notable increasing since the 1990’s. By pyrolysis or
chemical recycling of both from plastic and solid wastes
considerable energy could be obtain in the form ofhydrocarbons. Many researchers investigate the possibleof waste to fuel processes and numerous having
prospective chance for industrial leading. Pyrolysis ofwaste plastics or polymer reach wastes both fromhouseholds and industrial companies (e.g. HDPE, LDPE,PP, PS, etc.) is one of the most attractive methods fortheir recycling and converting to valuable hydrocarbon
products.
In this work we have focused to determine the correlation
between properties of raw materials and products
quantity and quality in case of waste plastic pyrolysis.
The mild pyrolysis of contaminated, polyolefin reach
waste plastics was investigated in a tube reactor bothabsence and presence of catalyst. Gases and liquids
formed in degradation reactions were analysed mainly bya gas-chromatography, Fourier-transformed infrared
spectroscopy, size exclusion chromatography and otherstandardized methods. Mainly the product quantity, theinteriores libro.indd 31

composition, impurities level and the other fuel properties
such as densitiy, heating value, pour point have beencompared.

2. Materials and Methods
In our experimental work different waste polymers havebeen used: automotive wastes (LDPE, HDPE, PP, PS,ABS, PC and PA), packaging wastes (HDPE, LDPE, PP)
and agricultural wastes (HDPE, LDPE, PP).
To ensure the higher yields of volatile products different
catalysts were applied: Y-zeolite, E-zeolite and MCM-41
catalyst.
Pyrolysis of waste polymers was carried out incontinuous reactor with feed rate of 10kg/h at 550°C.
Raw material was mixed with the catalyst then that
mixture was fed in the reactor by an extruder, where thepolymer was preheated. The extruder was directly
connected to the reactor beginning section. Inside thegas heated reactor the waste polymer had melted andtheir carbon chain cracked into fragments with lower
molecular weights. For adjusting the temperature
constantan thermocouples and electronic PID controllers
were used both in the extruder and pyrolysis reactor. In
the distillation column hydrocarbons were separated into
different products.
Gases were analyzed using a Carlo-Erba Vega Series
GC 6000 gas chromatograph provided with a 50 m u
0.32 mm fused silica column with Al2O3/KCl coating, at
40°C.

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6th International Symposium on Feedstock Recycling of Polymeric Materials

The composition of liquids products were analyzed bygas chromatograph (TRACE GC) with a flame ionization
detector. It was provided with a 30m x 0.32mm Rtx®-1(Crossbond® 100% Dimethyl-polysiloxane) column.
The main chemical bonds of liquids were determined with
infrared technique by a TENSOR 27 type Fouriertransformed infrared spectrometer in the 400-4000cm-1
wave number range.
The average molecular weight of heavy oils and its
distribution were measured by size exclusion
chromatography (Waters system).
Hydrocarbon fraction from pyrolysis, experimental
additives and reinforced plastic composites were also
analyzed using standardized methods: determination of
distillation curve (ASTM-D 1078), flash point (ISO2719:2002 and MSZ 15967:1979), CFPP (MSZ EN116:1999), viscosity (MSZ ISO 3105:1998), corrosion
test (MSZ EN ISO2160:2000), liquid density
measurement (MSZ EN ISO 12185) determination ofsulphur content (ASTMD 6428 99), determination of
nitrogen content (ASTMD 6366 99).
The concentration of other impurities in products wasfollowed with energy dispersive X-ray fluorescencemethod (Phillips PW 4025/02 MiniPal), while octane andcetane numbers were determined from their infrared
spectra with a ZX-101c type instrument.

3. Results and Discussion
The yields of products obtained from different raw
materials have shown quite significant differences. The
highest yields of middle distillates was found in case of
raw materials from packaging sector, while the lowest
from automotive area. The yields of valuable lighter
fractions could be increased by the presence of anycatalysts. The most efficient catalyst was the Y-zeolite foroil production, while the HZSM-5 catalyst in gasproduction. Results could be blamed be the differences
in catalyst micro- and macropores surface areas.
Compositions of non-condensed products at 20°C areshown compounds from C1 to C5 hydrocarbons both
catalytic and non-catalytic cases. The formation ofalkenes were a bit higher that alkanes of same carbon
number. Detectable amount of i-butane appeared only inthe presence of catalyst, which refers to theirisomerisation of effect. The calculated heating values ofgases was 45.9-46.6kJ/mol, which is enough high forenergy generation to heat consumption of pyrolysis.
The hydrocarbon compositions the other properties of the
produced liquid fractions could be affected by the raw
materials and the presence of catalysts. The highest
impurities were found in case of products obtained fromautomotive and agricultural raw materials, but all
unfavorable properties could be improved by catalysts.
Catalysts can occur the isomerization of double bond andthe main carbon frame, moreover occasionally led todecrease the impurity level.
The other properties of liquid hydrocarbons e.g.
hydrocarbon distribution, structure, density, average
molar mass, boiling point ranges, etc. have also shown

interiores libro.indd 32

favourable properties for further energetic utilization
depending on the raw materials. The boiling points werein the range of 30-270°C in case of middle distillates,
while heavy oils could be characterized as hydrocarbons
with boiling points over 150°C. In products Na, Ca, Na,P, K, Mg and N, S, Fe, Mo, Co were identified ascontaminants.

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