Moreover, PE degradation follows a free radical chain process and hydrogenation process, while PS follows a radical chain process including various steps (Kiran et al., 2000). Figure 4. Stab. The quality and yield of pyrolysis products such as liquid oil, gas, and char were studied. 98, 972979. 94, 209214. 186, 189196. The NIST08s mass spectral data library was used to identify the chromatographic peaks, and the peak percentages were assessed for their total ion chromatogram (TIC) peak area. Bomb Calorimeter and TGA (Mettler Toledo TGA/SDTA851) by adopting the standard ASTM methods. doi: 10.1016/S0141-3910(01)00264-6, De Wild, P. J., Huijgen, W. J., and Gosselink, R. J. Plastic waste production and consumption is increasing at an alarming rate, with the increase of the human population, rapid economic growth, continuous urbanization, and changes in life style. doi: 10.1016/j.fuel.2014.05.028, Keywords: catalytic pyrolysis, pyrolysis based biorefineries, natural zeolite, plastic waste, aromatic compounds, modified natural zeolite, catalyst, Citation: Miandad R, Rehan M, Barakat MA, Aburiazaiza AS, Khan H, Ismail IMI, Dhavamani J, Gardy J, Hassanpour A and Nizami A-S (2019) Catalytic Pyrolysis of Plastic Waste: Moving Toward Pyrolysis Based Biorefineries. The high production of gas may be due to the presence of PP. The produced liquid oil from catalytic pyrolysis of PE/PP contains aromatic, olefin, and naphthalene compounds. Adnan et al. Res. Also, the characteristics of this process are relatively long residence times of waste in the reactor, poor temperature control due to large temperature gradients across their internal dimensions, fouling walls of the reactor by carbon residue and low liquid product quality due to the production of a diverse number of pyrolysis products. doi: 10.1016/0141-3910(90)90002-O, Miandad, R., Barakat, M. A., Aburiazaiza, A. S., Rehan, M., Ismail, I. M. I., and Nizami, A. S. (2017b). Energy. Polish J. Environ. Furthermore, they generate substantial economic benefits and can help achieve a circular economy in any country. These biorefineries can play a significant role to reduce waste-related environmental pollution and GHG emissions. Pyrolysis 117,7281. doi: 10.1016/j.energy.2016.06.024, Lecomte, H. A., and Liggat, J. J. 1000 g of feedstock was used, with 100 g of catalyst in each experiment. (2018). The catalytic pyrolysis of individual PS plastic using TA-NZ and AA-NZ catalysts showed the highest liquid oil yields of 70 and 60%, respectively, compared to all other types of individual and combined plastic waste studied. Various researchers have reported that PE and PET degradation requires higher temperatures compared to other plastics (Dimitrov et al., 2013; Rizzarelli et al., 2016). The mesoporous and acidic catalyst leads to the production of shorter chain hydrocarbon due to its high cracking ability (Lopez et al., 2011). Pyrolysis of municipal plastic wastes for recovery of gasoline-range hydrocarbons. doi: 10.1016/S0926-3373(99)00130-7, Serrano, D. P., Aguado, J., and Escola, J. M. (2012). If it contains a lot of various contaminative materials in waste plastics, it leads to poor economics by increasing the recycling procedure cost. The disposal of plastic waste in landfills provide habitat for insects and rodents, that may cause different types of diseases (Alexandra, 2012). 1, 7484. (2002) reported that PP degradation produces maximum gas in the presence of acid catalysts. Technol. Appl. The integrated approach helps to achieve maximum economic and environmental benefits with minimal waste production. (2008) carried out pyrolysis of plastic waste with modified MCM-41 and HZSM-5 and reported that use of HZSM-5 produced lighter hydrocarbons (C3C4) with maximum aromatic compounds. The residue (char) left after the pyrolysis process can be utilized for several environmental applications. 28, 131151. Int. The studies were carried out to explore the potential of produced liquid oil in the context of engine performance and vehicle exhaust emission. A continuous condensation system using a water bath and ACDelco Classic coolant was used to ensure the condensation temperature was kept below 10C, and to ensure the maximum condensation of vapor to liquid oil. Waste Manag. Influence of temperature and reaction time on the conversion of polystyrene waste to pyrolysis liquid oil. The char production was lowest in this case, 7.2 and 13.0% with AA-NZ and TA-NZ, respectively. Received: 15 November 2018; Accepted: 22 February 2019; Published: 19 March 2019. Yield and composition of gases and oils/waxes from the feedstock recycling of waste plastic. In Feeds Tock Recycling and Pyrolysis of Waste Plastics: Converting Waste Plastics into Diesel and Other Fuels, eds J. Scheirs and W. Kaminsky (West Sussex: John Wiley & Sons Press), 285309. Energy Fuels 29, 60686077. Kinetics of the thermal and thermo-oxidative degradation of polystyrene, polyethylene and poly (propylene). Technol. By preheating the plastic feedstock the melting time in the melting reactor can be shorted thus improving production rates. (2015) and Rehan et al. (2006) carried out pyrolysis of PS with PE with a ratio of 10 and 90%, respectively, and reported the maximum production of aromatics even at a very low ratio of PS. Catalysts have a very critical role in promoting process efficiency, targeting the specific reaction and reducing the process temperature and time (Serrano et al., 2012; Ratnasari et al., 2017). The energy and value- added products from pyrolysis of waste plastics, in Recycling of Solid Waste for Biofuels and Bio- Chemicals, eds O. P. Karthikeyan, K. H. Subramanian, and S. Muthu (Singapore: Springer), 333355. 119, 162175. Degrad. doi: 10.1016/S0141-3910(01)00162-8, Lin, Y. H., Yang, M. H., Yeh, T. F., and Ger, M. D. (2004). For the processes of different reactor types, kiln and retort pyrolysis processes are characterized by a relatively low capital investment. A similar two-stage degradation pattern was observed for PET plastic and the initial degradation started at 400C with a sharp decrease in weight loss. The pyrolysis oil was characterized using different techniques such as gas chromatography coupled with mass spectrophotometry (GC-MS), Fourier transform infrared spectroscopy (FT-IR). However, microporous and less acidic catalysts favor the production of long chain hydrocarbons as the cracking process occurred only on the outer surface of the catalysts. Thermochim. doi: 10.1016/j.jaap.2015.12.014, Saptoadi, H., and Pratama, N. N. (2015). Polym. doi: 10.1016/0141-3910(91)90119-C, McNeill, I. C., Zulfiqar, M., and Kousar, T. (1990). The lowest HHV of 41.7 MJ/ kg was found in liquid oil obtained from PS using the TA-NZ catalyst, whereas the highest HHV of 44.2 MJ/kg was from PS/PE/PP using the AA-NZ catalyst. PEs initial degradation started at 270C and propagated slowly but gradually until the temperature reached 385C.

Nizami, A. S., Ouda, O. K. M., Rehan, M., El-Maghraby, A. M. O., Gardy, J., Hassanpour, A., et al. Utilization of plastics waste oil as partial substitute for kerosene in pressurized cookstoves. Batool et al. J. Sci. Table 2. Copyright 2019 Miandad, Rehan, Barakat, Aburiazaiza, Khan, Ismail, Dhavamani, Gardy, Hassanpour and Nizami. (A,B) GC-MS of liquid oil produced from different types of plastic waste with TA-NZ. (2018). TGA was carried out on feedstock to obtain the optimal process conditions such as temperature and reaction time (75 min) under controlled conditions. The catalytic pyrolysis of PS with PE (50/50% ratio) in the presence of TA-NZ catalyst produced 44% liquid oil, however 52% liquid oil was obtained using the AA-NZ catalyst. A slight decrease in the liquid oil yield from AA-NZ could be due to its high acidity. doi: 10.1016/S0920-5861(00)00409-0, Waqas, M., Rehan, M., Aburiazaiza, A. S., and Nizami, A. S. (2018). Biodegrad. Finally, the product obtained is separated from the distillation tower, such as gas product, light oil product and heavy oil product. Further comparison with known (CRM) standards enabled confirmation of the identified compounds. Waste plastics mixture of polystyrene and polypropylene into light grade fuel using Fe2O3 catalyst. The aromatic compounds found in oil, from PS and PE, were higher than PP using the TA-NZ catalyst. In addition, the short life span of plastic accelerates the production of plastic waste on a daily basis. doi: 10.1016/j.proenv.2014.03.028, Syamsiro, M., Cheng, S., Hu, W., Saptoadi, H., Pratama, N. N., Trisunaryanti, W., et al. Catalytic degradation of waste polypropylene by pyrolysis. Ma et al. Liquid and gaseous fuel from waste plastics by sequential pyrolysis and catalytic reforming processes over indonesian natural zeolite catalysts. Stab. The experiments were carried out in a small pilot-scale pyrolysis reactor at 450C, using a heating rate of 10C/min and reaction time of 75 min (Figure 1). 2/S/1438.

Moreover, the HHV of the produced liquid oil has been found in the range of 41.744.2 MJ/kg (Table 2) which is very close to the energy value of conventional diesel. Saudi natural zeolite catalyst was modified via novel thermal activation (TA-NZ) at 550C and acid activation (AA-NZ) with HNO3 to enhance its catalytic properties. Comput. The pyrolysis oil obtained from various plastic types need to be cleaned significantly before it is used in any application, to ensure minimal environmental impact. Overall, in the presence of catalysts, PE and PP follow the Random-chain scission mechanism, while PS follows the unzipping or end chain scission mechanism (Cullis and Hirschler, 1981; Peterson et al., 2001). Eng. Eng. Energy Res. Bernando, M. (2011). 11, 22781684. are basically shown in Figure 5.3, Waste plastics as a reactant for obtaining the valuable products are invariably contaminated with materials such as soil, iron and wood etc. doi: 10.1016/j.cej.2012.06.146, Ogawa, T., Kuroki, T., Ide, S., and Ikemura, T. (1982). Degradation mechanism of diethylene glycol units in a terephthalate polymer. 86, 499504. For a reactor with a big diameter in a large-scale plant the temperature gradient must also be taken into consideration in determining the degradation temperature, because of heat transfer limitations for viscous fluids with low thermal conductivity in the large reactor. Sci. J. Appl. (2004) reported the maximum production of gas and char with negligible liquid oil production from catalytic pyrolysis of PET. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). Catalytic degradation of polypropylene over alumina loaded mesoporous catalysts. Chem. The liquid oil produced from catalytic pyrolysis of PS, with both activated catalysts, mainly contains aromatic hydrocarbons with some paraffins, naphthalene and olefin compounds (Rehan et al., 2017). J. (1982) carried out pyrolysis of PS with the alumina-silica catalyst at 300C and found the hydrogenation of styrene to its derivate. Polym. Stab. doi: 10.1002/1521-3935(20010301)202:6<775::AID-MACP775>3.0.CO;2-G, Ramli, M. R., Othman, M. B. H., Arifin, A., and Ahmad, Z. However, the second degradation started at a slightly higher temperature (550C). In order to obtain an oil product in the pyrolysis of waste plastics, the major steps for waste plastics that are derived from the household, industry, etc. 241, 11011117. Wu, C., and Williams, P. T. (2010). (2013). Environ. The catalytic pyrolysis of PP/PE (50/50% ratio) did not show any significant difference in the overall product yields when using both AA-NZ and TA-NZ. The produced liquid oil was collected from the oil collection tank, and further characterization was carried out to uncover its chemical composition and characteristics for other potential applications. 127, 157162. doi: 10.7763/IJESD.2015.V6.619. The degradation of PP enhances the carbocation process due to the presence of tertiary carbon in its carbon chain (Jung et al., 2010). Authors are also thankful to Deanship of Scientific Research (DSR) at KAU for their financial and technical support to CEES. In reality however, oil from most plastic waste has a complex chemical structure and may contain other groups of unidentified chemicals such as sulfur, nitrogen, and oxygen-containing hydrocarbons. doi: 10.1016/j.enconman.2017.03.071, Yoshioka, T., Grause, G., Eger, C., Kaminsky, W., and Okuwaki, A. (1997) reported the production of aromatics and aliphatic compounds from the catalytic pyrolysis of PE with HZSM-5, while the use of mesoporous MCM-41 decreased the aromatic compounds produced due to its low acid catalytic activity. The TA-NZ and AA-NZ catalysts showed a different effect on the wt% of catalytic pyrolysis products and liquid oil chemical compositions, with AA-NZ showing higher catalytic activity than TA-NZ. Eng. Nileshkumar, K. D., Jani, R. J., Patel, T. M., and Rathod, G. P. (2015). The catalytic pyrolysis of PS mainly produces styrene and its derivate as the major compounds in the produced liquid oil (Siddiqui and Redhwi, 2009; Rehan et al., 2017). Figure 6. The obtained yield of each pyrolysis product was calculated based on weight, after the completion of each experiment. 18, 22312239. In addition, in the presence of acidic catalysts, due to carbenium mechanism, the formation of aromatic and olefin compound production may increase (Lee, 2012). The identified peaks were matched with the NIST and mass bank spectra library. Biorefining 8, 645657. (2014). (2016). Int. This is why a more in-depth and accurate qualitative chemical analysis is needed to fully understand the chemistry of pyrolysis oil, using advanced calibration and standardization and using different MS detectors like SCD and NCD as well as different GC columns. The use of HZSM-5 increased liquid oil production with the composition of aromatics and isoalkanes compounds. The degradation temperature must be decided by the type and composition of plastics contained in mixed thermoplastics, because of their different degradation temperatures. The high char production numbers were due to the high acidity of the catalyst, which favors char production via intense secondary cross-linking reactions (Serrano et al., 2000). 102, 822838. Phys. Part I: synthesis and thermal properties. The pyrolysis reactor can hold up to 20 L of feedstock and the maximum working safe temperature of up to 600C can be achieved with the desired heating rates. (2011) reported the possible degradation mechanism of PS on acid catalysts that may occur due to the attack of a proton associated with Bronsted acidic sites, resulting in the carbenium ion mechanism, which further undergoes -scission and is later followed by hydrogen transfer. catalytic pyrolysis psw pyrolysis plastic plant tire waste oil safety doing calculation accurate device system machine pyrolysis distillation wastetireoil polyethylene

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