Kazakhstan journal for oil & gas industryKazakhstan journal for oil & gas industry2707-42262957-806XKMG Engineering10898210.54859/kjogi108982Review ArticleAnalysis of the influence of process parameters on the formation of liquid products during the pyrolysis of polystyrene wasteKizatovYessmagambet M.k1z4.workstation@gmail.comhttps://orcid.org/0009-0001-1078-3059DyussovaRizagul M.<p>Cand. Sc. (Engineering)</p>dyussova_rm@enu.kzhttps://orcid.org/0000-0003-3083-5255KopishevEldar Ye.<p>Cand. Sc. (Chemistry), Associate Professor</p>kopishev_eye@enu.kzhttps://orcid.org/0000-0002-7209-2341KaliyevOlzhas Ye.kaliyev_oye_3@enu.kzhttps://orcid.org/0009-0008-4860-060XEurasian National University30062026821051180605202622052026Copyright © 2026, Kizatov Y.M., Dyussova R.M., Kopishev E.Y., Kaliyev O.Y.2026<p>This study examines the thermal treatment of polystyrene waste as an effective alternative to conventional mechanical recycling. Given the growing volume of plastic waste and the complexity of processing foamed materials, an analysis was conducted of recent publications on the influence of process parameters on the yield and composition of liquid pyrolysis products. Particular attention was paid to the effects of temperature and residence time in the reaction zone. Based on the analysis, it was established that the most optimal temperature range is 400–500°C. It is under these conditions that the maximum yield of the liquid fraction, enriched with valuable aromatic compounds, including styrene, benzene, toluene, and ethylbenzene is achieved. As a result, it was found that deviations from the optimal temperatures lead either to incomplete polymer degradation or to excessive gas formation. The advantages of pyrolysis in the processing of contaminated and expanded polystyrene materials were highlighted. Additionally, the importance of improving the efficiency of polymer waste processing technologies in the context of increasing environmental pressure is emphasized. It is concluded that the technology has significant potentialfor the production of chemical feedstocks and the development of a circular economy, provided that systems for sorting, purifying, and subsequent fractionation of pyrolysis products are improved.</p>recyclingpyrolysispolystyreneprocess temperatureresidence timeқайта өңдеупиролизполистиролпроцесс температурасыпроцесс ұзақтығыпереработкапиролизполистиролтемпература процессапродолжительность процессаPerreard S, Boucher J, Gallato M. Plastic Overshoot Day – Report 2025. EA-Earth Action; 2025.kaz-waste.kz [Internet]. KazWaste – Kazakhstan Association for Waste Management. Ministerstvo ekologii podvelo itogi: rezul’taty v sfere upravleniya otkhodami [cited 2026 March 13]. Available from: kaz-waste.kz/news/936/. (In Russ).caclimate.fund [Internet]. CACF. More than 30% of waste was recycled and 95% of illegal dumpsites were eliminated in Kazakhstan in 2025 [cited 2026 March 13]. Available from: caclimate.fund/novosti/bolee-30-othodov-utilizirovano-i-95-stihiynyh-svalok-likvidirovano-v-kazahstane-v-2025-godu.Lee Y, Cho J, Sohn J, Kim C. Health Effects of Microplastic Exposures: Current Issues and Perspectives in South Korea. Yonsei Med J. 2023;64(5):301–308. doi: 10.3349/ymj.2023.0048.Schyns ZOG, Shaver MP. Mechanical recycling of packaging plastics: a review. Macromolecular Rapid Communications. 2021;42(3):2000415. doi: 10.1002/marc.202000415.Kulakovskaya A, Wiprächtiger M, Knoeri C, Bening CR. Integrated environmental-economic circular economy assessment: Application to the case of expanded polystyrene. Resources, Conservation and Recycling. 2023;197:107069. doi: 10.1016/j.resconrec.2023.107069.Yelemessova Z, Kopishev E, Dyussova R, et al. Sustainable plastic waste management: global practices and perspectives on the case of Kazakhstan. International Journal of Innovative Research and Scientific Studies. 2025;8:1161–1179. doi: 10.53894/ijirss.v8i1.4547Silva RJDO, Graf K, Leite Ribeiro Okimoto ML. Plastic waste recycling: an overview of the mechanical, chemical, and thermal technologies. Journal of Engineering and Applied Science. 2025;72:251. doi: 10.1186/s44147-025-00799-2.Achilias DS. Thermo-chemical recycling of plastics as a sustainable approach to the plastic waste issue. Euro-Mediterranean Journal for Environmental Integration. 2025;10:2605–2618. doi: 10.1007/s41207-025-00800-7.Yaqoob H, Ali HM, Khalid U. Pyrolysis of waste plastics for alternative fuel: a review of key factors. RSC Sustainability. 2025;3(1):208–218. doi: 10.1039/D4SU00504J.Alrazen HA, Aminossadati SM, Mahmood HA, et al. A review of the pathways, limitations, and perspectives of plastic waste recycling. Materials for Renewable and Sustainable Energy. 2025;14:50. doi: 10.1007/s40243-025-00328-4.Alabi OO, Akande TO, Gbadeyan OJ, Deenadayalu N. Advanced technologies for plastic waste recycling: examine recent developments. RSC Advances. 2025;15(48):40541–40557. doi: 10.1039/D5RA06715D.Lee SW, Jeong SJ, Hidajat MJ, et al. Sustainable chemical recycling of waste polystyrene via catalytic pyrolysis. ACS Omega. 2025;10(43):51406–51418. doi: 10.1021/acsomega.5c06944.Jeswani H, Krüger C, Russ M, et al. Life cycle environmental impacts of chemical recycling via pyrolysis. Science of the Total Environment. 2021;769:144483. doi: 10.1016/j.scitotenv.2020.144483.Halba A, Thengane SK, Arora P. A critical outlook on lignocellulosic biomass and plastics co-gasification. Energy & Fuels. 2022;37(1):19–35. doi: 10.1021/acs.energyfuels.2c02907.Laghezza M, Fiore S, Berruti F. A review on the pyrolytic conversion of plastic waste into fuels and chemicals. Journal of Analytical and Applied Pyrolysis. 2024;179:106479. doi: 10.1016/j.jaap.2024.106479.Hasan MM, Haque R, Jahirul MI, Rasul MG. Pyrolysis of plastic waste for sustainable energy recovery. Energy Conversion and Management. 2025;326:119511. doi: 10.1016/j.enconman.2025.119511.Li Y, Zhang C, Wang W, et al. A study on the pyrolysis and product regulation mechanism of waste polystyrene. Molecules. 2025;30(3):727. doi: 10.3390/molecules30030727.Royuela D, Veses A, García T, et al. Advances in the circular economy of polystyrene. Journal of Environmental Chemical Engineering. 2026;14(2):121633. doi: 10.1016/j.jece.2026.121633.Gonzalez-Aguilar AM, Pérez-García V, Riesco-Ávila JM. A thermo-catalytic pyrolysis of polystyrene waste review. Polymers. 2023;15(6):1582. doi: 10.3390/polym15061582.Park KB, Jeong YS, Guzelciftci B, Kim JS. Two-stage pyrolysis of polystyrene. Appl Energy. 2020;259:114240. doi: 10.1016/j.apenergy.2019.114240.Holtkamp M, Renner M, Matthiesen K, et al. Robust downstream technologies in polystyrene waste pyrolysis. Resources, Conservation and Recycling. 2024;205:107558. doi: 10.1016/j.resconrec.2024.107558.Gonzalez-Aguilar AM, Cabrera-Madera VP, Vera-Rozo JR, Riesco-Ávila JM. Effects of heating rate and temperature on the thermal pyrolysis of expanded polystyrene. Polymers. 2022;14(22):4957. doi: 10.3390/polym14224957.Miandad R, Nizami AS, Rehan M, et al. Influence of temperature and reaction time on the conversion of polystyrene waste. Waste Manag. 2016;58:250–259. doi: 10.1016/j.wasman.2016.09.023.