Thermal cracking of waste biomass/plastics mixtures

Table 4. Composition of feedstock samplesSampleComposition (%wt.)LLDPE LDPE HDPE PP PS PET PVC beech used tireswood1 22.9 22.9 22.9 9.5 9.5 10.7 1.1 0 02 0 0 0 0 0 0 0 100 03 0 0 0 0 0 0 0 0 1004 11.5 11.5 11.5 4.8 4.8 5.3 0.5 50 05 11.5 11.5 11.5 4.8 4.8 5.3 0.5 0 506 0 0 0 0 0 0 0 50 507 7.7 7.7 7.7 3.2 3.2 3.5 0.4 33.4 33.43. Results and DiscusionIn gas products we focused on quantitative analysis of carbon monoxide, carbon dioxide,methan, ethan, ethylene, propane, propene and hydrogen. In liquid products from mixture ofplastics we focused on 1-alkenes and alkanes, from beech wood on oxygene derivates andfrom tires on aromates and isoprene (Table 5.). We compared yields with previous study.There are differences in yields of carbon monoxide and carbon dioxide in this study (traces)in comparison with the prewious study [4]. Yields of other main products from thermalcracking of plastic mixtures were increased. There is a compilance with study [7] in yields ofcarbon oxides in the gas fraction from pyrolysis if beech wood. In liquid fraction from usedtires pyrolysis we noted increased yields of aromatics compared with study [5].Material balance was calculated after each experiment. These dates are given in table6.

Table 5. Comparison of yields of main agents for individually materialsSample/component1 2 3 4 5 6 7exp. [4] exp. [7] exp. [5] exp. [8] exp. exp. exp.Yields of gaseous components [%wt.]Carbon oxide traces 0.6 3.5 12.9 0.3 0.7 0.2 1.7 0.3 2.6 0.3Carbon dioxide traces 6.8 16.6 8.7 3.7 5.2 19.4 24.6 4.7 2.6 11.4Hydrogen - - - traces 0.2 - - - traces -Methane 1.6 1.0 1.2 1.9 0.8 1.0 0.4 1.2 0.4 1.3 0.3Ethane 6.6 2.7 0.7 0.4 1.1 0.7 0.6 0.4 1.0 1.9 0.2Ethylene 4.5 3.9 0.3 0.3 0.4 0.5 0.3 0.6 0.5 1.1 0.1Propane 11.6 2.6 0.3 0.1 1.2 0.6 0.5 0.2 1.4 2.7 0.1Propene 14.3 6.4 0.4 0.3 1.0 0.9 0.6 0.4 1.6 3.2 0.2Yields of liquid components [%wt.]1-Heptene- 3.7 - - - - 3.9 1.3 0.4 - 0.5+heptane1-Octene2.0 3.0 - - - - 0.2 0.9 0.8 - -+octane1-Tetradecene 1.0 2.0 - - - - traces 0.9 - - -+tetradecane1-Hexadecene 0.6 1.1 - - - - - 0.4 0.9 - 0.3+hexadecane1-Heptadecene 0.7 1.0 - - - - - 0.2 - - -+heptadecaneMethanol - - 4.3 0,6 - - 1.4 3.9 - 3.7 -Acetic acid - - 13.5 4,3 - - 3.4 2.6 - 0.7 -Formic acid - - 2.1 4,7 - - 0.6 1.4 - 8.2 -Furfural - - 1.0 2,4 - - 0.2 1.5 - 0.5 -Lactic acid - - 0.4 1,0 - - 0.9 0.4 - - -Phenol - - 0.3 - - - traces 1.4 - - -Levoglukosane - - 0.8 0.4 - - - 0.4 - - -Benzene - - - - 9.3 3.2 - - - - -Isoprene - - - - 11.1 5.0 - - 4.7 1.8 2.2Toluene - - - - 5.8 2.1 - - 3.9 2.9 8.3Ethylbenzene - - - - 0.2 1.0 - - 0.1 - -p+m-Xylene - - - - 0.5 1.2 - 2.0 0.3 - -Methylstyrene - - - - 0.2 1.2 - - 1.6 - -d,l-Limonene - - - - 2.7 9.0 - - 3.6 0.9 1.6Naphthalene - - - - 0.1 1.7 - - - 1.5 -Other componentsin gas and liquidproducts57.1 65.2 54.6 62.0 61.4 66.0 67.4 53.8 73.8 64.4 74.5Table 6. The comparison of experimental and theroetical yields of gases, liquids and solidresidueSample 1 2 3 4 5 6 7exp. [4] exp. [7] exp. [5] exp. teor. [8] exp. teor. exp. teor. exp. teor.Gas 28.4 30.5 35.4 25.1 16.4 11.1 35.7 31.9 30.3 17.4 22.4 29.8 25.9 16.9 26.7Liquid 70.5 65.9 40.5 44.3 48.9 42.6 49.0 55.5 43.8 48.5 59.7 34.3 44.7 53.7 53.2Solid residue 1.2 3.6 24.1 30.6 34.7 46.3 15.3 12.6 25.9 34.1 17.9 35.9 29.4 29.4 20.0

The yields of gas, liquid and solid residue from pyrolysis of plastic mixture areidentical as in study [4]. Differences in this study and in previous study of beech woodpyrolysis is in increased yield of gas fraction and reduced yield of liquid fraction and solidresidue [7].By the pyrolysis of plastics and wood mixtures (1:1) was noted a deviation from thetheoertical estimates. The reduction of oxygene species was also noted. This decreasingmeans, that the addition of plastics into the feed caused the decomposition of oxygen speciesto carbon monoxide. Sharypov et al.[9] reported that the production of carbon monoxidecould be reduced to value of 6.5 wt% by using a mixture which contains beech wood andpolypropylene 1:1. The reactor was a rotary autoclave from stainlass steel. The perssure in thereactor was 3 MPa, max. 5.5 MPa. Ouminiga et al.[10] reported that higher yields of carbonoxides could be achieved by flash pyrolysis at temperatures of 800-1000°C. The amount ofcarbon dioxide was 7-12 wt% and of carbon monoxide was 19-26%. The yield of methanewas higher: 7-9 wt%, and the yields of other hydrocarbons were decreased.4. ConclusionThe possibilities of pyrolysis and copyrolysis in the recycling of plastics, biomass, usedtires and its mixtures were studied. We have also registered the possible dependences anddifferences between the theoretical and calculated values of yield for gases, liquids and solidresidue as well as individual products.AcknowledgmentWewould like to thank the VEGA Scientific Grant of the Slovak Republic, for financialsupport of this research through the Research Project No. 1/0228/12.5. References[1] Q. Cao, L. Jin, W. Bao, Y. Lu, Fuel Processing technology 90 (2009) 337- 342[2] P. T. Williams, Waste Treatment and Disposal Second Edition, John Wiley & Sons Ltd.England, 2009, pp. 326-336, ISBN 0-470-84913-4[3] E. Hájeková, M. Bajus, J. Anal. Appl. Pyrolysis 74 270-281, 2005[4] M. Bajus, E. Hájeková, Petroleum and Coal 52 (3) 164-172, 2010[5] M. Bajus, N. Olahová, Petroleum and Coal 53 (2) 98-105, 2011[6] M. Miranda, F. Pinto, J. Gulyurtlu, J. Cabrita, A. C. Nogueira, A. Matos, Fuel 89 2217-2229, 2010[7] M. Bajus, Petroleum and Coal 52 (3) 207-214, 2010[8] M. Bajus, Petroleum and Coal 53 (1) 1-7, 2011[9] V. I. Sharypov, N. Marin, N. G. Beregovtsova, S. V. Baryshnikov, B. N. Kuznetsov, V. L.Cebolla, J. V. Weber, J. Anal. Appl. Pyrolysis 64 (2002) 15-28[10] S. K. Ouminga, T. Rogaume, M. Sougoti, J. M. Commandre, J. Koulidiati, J. Anal. Appl.Pyrolysis 86 (2009) 260-268