Hydrocarbons obtained by pyrolysis of contaminated waste plastics

45th International Petroleum Conference, June 13, 2011, Bratislava, Slovak Republic 4100Composition, %80604020GasLiquidHeavy oil0Thermal Y-zeolite Thermal Y-zeolite Thermal Y-zeoliteOriginal Motor oil flasks Washed motor oilflasksFig. 3 – Product yieldsComposition of gas and liquid productsComposition of gases was analyzed by a gas-chromatograph. All of the gaseous productswere in the carbon number range C 1 -C 5 . In every case two dominant componentscould be observed: C 2 and C 4 . This could be explained with the structure and degradationmechanism of polyethylene because it is built up from C 2 monomers. In thermalcases saturated and unsaturated linear hydrocarbons were dominant. The gasesevolved during thermo-catalytic pyrolysis contained i-C 4 and i-C 5 molecules.100Composition, %806040AromaticBranchedn-Alkenesn-Alkanes200Thermal Y-zeolite Thermal Y-zeolite Thermal Y-zeoliteOriginal Motor oil flasks Washed motor oilflasksFig. 4 – Composition of liquid productsComposition of liquid products is shown in Fig. 3. According to Fig.3 it can be seenthat the n-alkanes and n-alkenes were the major components of the liquid fractions.Moreover branched and aromatic hydrocarbons could be also detected. The use ofcatalyst did not affect significantly the composition of liquid products obtained by thepyrolysis of motor oil flask. However in the case of the pyrolysis of original HDPEthe catalyst increased the concentration of the branched and aromatic hydrocarbons inthe liquid product. Thus it can be stated that the isomerisation effect of the catalyst

45th International Petroleum Conference, June 13, 2011, Bratislava, Slovak Republic 5was not realized at the pyrolysis of the contaminated raw materials, because contaminantsdeactivated the applied catalyst.(a)25Composition, %2015105ThermalY-zeolite05 6 7 8 9 10 11 12 13 14 15 16 17 18Carbon number(b)Composition, %1816141210864205 6 7 8 9 10 11 12 13 14 15 16 17 18Carbon numberThermalY-zeolite(c)Composition, %201816141210864205 6 7 8 9 10 11 12 13 14 15 16 17 18Carbon numberThermalY-zeoliteFig. 4 – Composition of liquid products: (a) Original raw material (b) Motor oil flasks (c) Washed motoroil flasks

45th International Petroleum Conference, June 13, 2011, Bratislava, Slovak Republic 6Carbon number distribution of liquid products is shown in Fig. 4 a-c. All of the liquidproducts were consisted of hydrocarbons from C 5 to C 18 . In Fig. 4a the carbon numberdistribution of liquid products obtained from thermal and thermo-catalytic pyrolysisof original HDPE are shown. In the thermo-catalytic case the liquid product containedlighter hydrocarbons compared to the thermal product. In other words the averagemolecular weight of the liquid product became lower. This phenomenon could not beobserved on the carbon number distribution of liquid products derived from the pyrolysisof motor oil flasks (Fig 4b and c). The two maximums of the carbon number distributioncurve could be explained with the heterogeneity of the raw material. The collectedmotor oil flasks were composed of polymers with different average molecularweight.Contaminant level of pyrolysis productsChlorine, sulphur and nitrogen content of pyrolysis products were analyzed. Contaminantsof the gas products (eg. HCl, HCN, H 2 S, NH 3 ) can be derived from the heteroatomcontent of the raw material. The chlorine concentration of gases was determinedand it was between 726 and 1003 ppm. The pre-treatment of the motor oil flask coulddecrease the chlorine content of the gas products by 10-20%.The concentration of contaminants in liquid products is shown in Fig. 5a-c. Accordingto Fig. 5 it can be observed that the degradation products of original HDPE containedsulphur, chlorine and nitrogen in negligible concentrations. Liquid products derivedfrom the pyrolysis of motor oil flasks contained chlorine between 591 and 862 ppm,sulphur between 273 and 428 ppm and nitrogen between 161 and 327 ppm. The pretreatmentof the raw material could decrease the contaminant level. The chlorine contentdecreased approximately by 27%, while sulphur and nitrogen content by 31% and45%, respectively.The concentration of contaminants in the heavy oil was lower than in the liquid products.The effect of the raw material pre-treatment on the contaminant concentration ofthe heavy oil could be also observed. The application of catalyst did not affect significantlythe contaminant level of products.(a)Sulphur content, ppm450400350300250200150100500Thermal Y-zeolite Thermal Y-zeoliteMotor oil flasksWashed motor oil flasks

45th International Petroleum Conference, June 13, 2011, Bratislava, Slovak Republic 7(b)Chlorine content, ppm10009008007006005004003002001000Thermal Y-zeolite Thermal Y-zeoliteMotor oil flasksWashed motor oil flasks(c)350Nitrogen content, ppm300250200150100500Thermal Y-zeolite Thermal Y-zeoliteMotor oil flasksWashed motor oil flasksFig. 5 – Contaminant level of liquid products: (a) Sulphur content (b) Chlorine content (c) NitrogencontentProperties of the pyrolysis productsThe properties of the products were determined which are important with respect tofurther utilization. According to Table 1 it can established that the density of liquidproducts decreased when Y-zeolite was applied. The density of the liquid productsderived from the pyrolysis of motor oil flask was higher than the sample derived fromthe HDPE pyrolysis. Corrosion tests of liquids from motor oil flasks shows that theyare in the 1/b class because of the heteroatom containing substances in the pyrolysisoils. All of the liquid products had a flashpoint below 22°C.The flashpoint, melting point and heating value of heavy oil were also determined(Table 2). Flashpoint and melting point of the samples derived from the pyrolysis oforiginal HDPE decreased by the application of catalyst, which shows the cracking activityof the Y-zeoilte. The properties of the samples derived from the pyrolysis ofmotor oil flasks did not show significant differences.

45th International Petroleum Conference, June 13, 2011, Bratislava, Slovak Republic 9[5] C. Vasile, H. Pakdel, B. Mihali, P. Onu, H. Darie, S. Ciocâlteu “Thermal and catalyticdecomposition of mixed plastics,” Journal of Analytical and Applied Pyrolysis,57 (2001) 287-303.[6] M. Blazsó, Zs. Czégény “Catalytic destruction of brominated aromatic compoundsstudied in a catalyst microbed coupled to gas chromatography/mass spectrometry,”Journal of Chromatography A, 1130 (2006) 91-96.[7] J. Aguado, D.P. Serrano, G. San Miguel, M.C. Castro, S. Madrid “Feedstock recyclingof polyethylene in a two-step thermo-catalytic reaction system,” Journal of Analyticaland Applied Pyrolysis, 79 (2007) 415-423.[8] W.J. Hall, P.T. Williams “Removal of organobromine compounds from the pyrolysisoils of flame retarded plastics using zeolite catalysts,” Journal of Analytical andApplied Pyrolysis, 81 (2008) 139-147.[9] A. López, I.de Marco, B.M. Caballero, M.F. Laresgoiti, A. Adrados, A. AranzabalČatalytic pyrolysis of plastic wastes with two different types of catalysts: ZSM-5 zeoliteand Red Mud,” Applied Catalysis B: Environmental, Article in press (2011).[10] G. Elordi, M. Olazar, G. Lopez, P. Castaňo, J. Bilbao “Role of pore structure inthe deactivation of zeolites (HZSM-5, H and HY) by coke in the pyrolysis of polyethylenein a conical spouted bed reactor,” Applied Catalysis B: Environmental, 102(2011) 224-231.[11] M.Olazar, G. Lopez, M. Amutio, G. Elordi, R. Aguado, J. Bilbao “Influence ofFCC catalyst steaming on HDPE pyrolysis product distribution,” Journal of Analyticaland Applied Pyrolysis, 85 (2009) 359-365.[12] Y.-H. Lin, M.-H. Yang, T.-T. Wei, C.-T. Hsu, K.-J. Wu, S.-L. Lee “Acid catalyzedconversion of chlorinated plastic waste into valuable hydrocarbons over postusecommercial FCC catalysts,” Journal of Analytical and Applied Pyrolysis, 87(2010) 154-162.[13] M. N. Siddiqui “Conversion of hazardous plastic wastes into useful chemicalproducts,” Journal of Hazardous Materials, 167 (2009) 728-735.[14] N. Miskolczi, A. Angyal, L. Bartha, I. Valkai “Fuels by pyrolysis of waste plasticsfrom agricultural and packaging sectors in a pilot scale reactor,” Fuel ProcessingTechnology, 90 (2009) 1032-1040.[15] H.-T. Lin, M.-S. Huang, J.-W. Luo, L.-H. Lin, C.-M. Lee, K.-L. Ou “Hydrocarbonfuels produced by catalytic pyrolysis of hospital plastic wastes in a fluidizingcracking process,” Fuel Processing Technology, 91 (2010) 1355-1363.[16] C. Wu, P.T. Williams “Pyrolysis-gasification of plastics, mixed plastics and realworldplastic waste with and without Ni-Mg-Al catalyst,” Fuel, 89 (2010) 3022-3032.