277284. 2, 4451. (2011). Lee (2gold necklace for teenage girl

91, 277284. 2, 4451. (2011). Lee (2012) reported that PS degradation occurred via both random-chain and end chain scissions, thus leading to the production of the stable benzene ring structure, which enhances further cracking and may increase liquid oil production. The produced liquid oil from catalytic pyrolysis of PE/PP contains aromatic, olefin, and naphthalene compounds. Energy Sources A 38, 25982603. The chemical composition of oil was studied using a GC-MS (Shimadzu QP-Plus 2010) with FI detector. Catalytic degradation of polystyrene over natural clinoptilolite zeolite. 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). Figure 3. Polym. 207, 421425. Life cycle optimization for sustainable design and operations of hydrocarbon biorefinery via fast pyrolysis, hydrotreating and hydrocracking. Stab. Detailed parameters of the pyrolysis reactor were published earlier (Miandad et al., 2016b, 2017b). Comput. Degrad. Technol. Peterson, J. D., Vyazovkin, S., and Wight, C. A. 98, 972979. To obtain a homogenous mixture, all the waste samples were crushed into smaller pieces of around 2 cm2. Polym. 34, 676682. The chemical composition of pyrolysis oil, by different functional groups, was studied using FT-IR. In addition, due to rapid urbanization, the land available for landfills, especially in cities, is reducing. The obtained data revealed the presence of aromatics and aliphatic functional groups in the oil (Figures 6, 7). The identified peaks were matched with the NIST and mass bank spectra library. The use of HZSM-5 increased liquid oil production with the composition of aromatics and isoalkanes compounds. Lin et al. 91, 517526. Res. 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. Miskolczi, N., Bartha, L., and Deak, G. (2006). 76, 6167. (2002) catalyst with low acidity and BET surface areas with microporous structures, favor the initial degradation of PP which may lead to the maximum production of gases. Furthermore, the addition of PET with PS, PE and PP (20/40/20/20% ratio) reduced the liquid oil yields down to 28 and 30% overall, using TA-NZ and AA-NZ catalysts, respectively, with higher fractions of char and gas. Tekin et al. Polym. Biorefineries have a great potential to convert waste into energy and other valuable products and could help to achieve circular economies. This is the first study to investigate the effect of modified Saudi natural zeolite, on product quality and yield from catalytic pyrolysis of plastic waste. Eng. 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. (2015) and Rehan et al. Int. Catalytic thermal cracking of postconsumer waste plastics to fuels. Dawood, A., and Miura, K. (2002). 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). (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. (2004). 34, 187204. (2016) carried out the thermal and catalytic pyrolysis of PE and reported that produced liquid oil contained alkanes and alkenes as a major functional group. TGA was carried out on feedstock to obtain the optimal process conditions such as temperature and reaction time (75 min) under controlled conditions. The initial degradation of PE and PET may be due to the presence of some volatile impurities such as the additive filler used during plastic synthesis (Dimitrov et al., 2013). Biodeterior. The availability of plastic and biomass waste streams as feedstocks for pyrolysis based biorefineries, is another major challenge, since recycling is not currently very efficient, especially in the developing countries. Stab. (2014). Similarly, more focus is needed to conduct further research and development work on enriching the biorefinery concept and to tap into its true potential. These findings are in line with other studies that carried out catalytic pyrolysis of PP with various catalysts (Marcilla et al., 2004). (2000). Ramli et al. doi: 10.1021/ef970055v. doi: 10.1002/1097-4628(20000829)77:9<1894::AID-APP5>3.0.CO;2-Y, Frigo, S., Seggiani, M., Puccini, M., and Vitolo, S. (2014). Energy Inst. Kim et al. Lee (2012) reported that PE has a long chain branched structure and that its degradation occurs via random chain scission, thus requiring a higher temperature, while PET degradation follows the ester link random scission which results in the formation oligomers (Dziecio and Trzeszczynski, 2000; Lecomte and Liggat, 2006). Alexandra, L. C. (2012). The liquid oil produced from the individual plastic types such as PS, PP and PE contained a mixture of aromatics, aliphatic and other hydrocarbon compounds. doi: 10.1016/j.tca.2006.09.013, Kim, J. R., Yoon, J. H., and Park, D. W. (2002). FT-IR analysis of liquid oil produced from catalytic pyrolysis with AA-NZ. doi: 10.1016/j.jtice.2015.01.015, Siddiqui, M. N., and Redhwi, H. H. (2009). MR and A-SN acknowledge the Center of Excellence in Environmental Studies (CEES), King Abdulaziz University (KAU), Jeddah, KSA and the Ministry of Education, KSA for financial support under Grant No. Moreover, the produced aromatic compounds can be used as raw material for polymerization in various chemical industries (Sarker and Rashid, 2013; Shah and Jan, 2015). Pyrolysis 72, 2733. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). Figure 6. 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). Saptoadi and Pratama (2015) successfully used pyrolytic liquid oil as an alternative in a kerosene stove. 18, 22312239. The pyrolysis oil was characterized using different techniques such as gas chromatography coupled with mass spectrophotometry (GC-MS), Fourier transform infrared spectroscopy (FT-IR). Ramli et al. Conversion of styrene into its derivate was increased in the presence of protonated catalysts due to hydrogenation (Kim et al., 2002). In TGA, a 10 g of each type of plastic waste was taken and heated with a rate of 10C from 25 to 900C under a continuous flow of nitrogen (50 ml/min). Bioresour. The liquid oil produced from the catalytic pyrolysis of PP/PE was 44 and 40% from TA-NZ and AA-NZ catalysts, respectively. (2012) and Panda and Singh (2013) also reported the presence of aromatics with some alkanes and alkenes from catalytic pyrolysis of PP. 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 catalytic pyrolysis of PS produced the highest liquid oil (70 and 60%) compared to PP (40 and 54%) and PE (40 and 42%), using the TA-NZ and AA-NZ catalysts, respectively. Conserv. The FT-IR analysis was conducted using a minimum of 32 scans with an average of 4 cm1 IR signals within the frequency range of 5004,000 cm1. The Combustion of Organic Polymers. doi: 10.1016/S0920-5861(00)00409-0, Waqas, M., Rehan, M., Aburiazaiza, A. S., and Nizami, A. S. (2018). The difference in TGA curves of various types of plastics could be due to their mesoporous structure (Chandrasekaran et al., 2015). Biodegrad. Lin et al. Appl. Conversion of methoxy and hydroxyl functionalities of phenolic monomers over zeolites. Fuel Process. J. Wu et al. The selection of these plastic materials was made based on the fact that they are the primary source of plastic waste produced in KSA. Lignin pyrolysis for profitable lignocellulosic biorefineries. Technol. The mesoporous and acidic catalyst leads to the production of shorter chain hydrocarbon due to its high cracking ability (Lopez et al., 2011). Manag. doi: 10.1016/j.jaap.2008.11.002, Ma, C., Yu, J., Wang, B., Song, Z., Xiang, J., Hu, S., et al. Biofuels Bioprod. (2017) also reported the dealkylation of styrene, due to the delay in evaporation inside the reactor, which may lead to an enhanced reforming process and result in the production of a styrene derivate. doi: 10.1016/j.energy.2015.07.030, Nizami, A. S., Rehan, M., Waqas, M., Naqvi, M., Ouda, O. K. M., Shahzad, K., et al. Eng. 31, 19731983. Investigation of catalytic degradation of high density, polyethylene by hydrocarbon group type analysis. Technol. Res. Appl. Stab. doi: 10.1016/j.fuel.2013.08.044. 5:18. doi: 10.5539/eer.v5n1p18, Lee, S. Y., Yoon, J. H., Kim, J. R., and Park, D. W. (2001). (2017). Appl. In addition, Lopez et al. Dev. The global plastic production was estimated at around 300 million tons per year and is continuously increasing every year (Miandad et al., 2016a; Ratnasari et al., 2017). Effect of zeolite catalysts on pyrolysis liquid oil. Proc. These biorefineries can play a significant role to reduce waste-related environmental pollution and GHG emissions. Utilization of plastics waste oil as partial substitute for kerosene in pressurized cookstoves. 2, 19241941. Figure 2. Gaca et al. Catalytic pyrolysis of low density polyethylene using cetyltrimethyl ammonium encapsulated monovacant keggin units and ZSM-5. Shah and Jan (2015) and Ukei et al. Effect of polyethylene terephthalate on the catalytic pyrolysis of polystyrene: Investigation of the liquid products. Analysis of recycled PET bottles products by pyrolysis-gas chromatography. Polym. In addition, the short life span of plastic accelerates the production of plastic waste on a daily basis. Resour. Eng. Fuel 116, 399408. According to Lee (2012) and Williams (2006), PE has a long chain carbon structure, and its degradation occurs randomly into smaller chain molecules via random chain scission, which may promote gas production. Sarker, M., and Rashid, M. M. (2013). The compounds were chosen based on the similarity index (SI > 90%). doi: 10.1016/j.jaap.2004.01.005, Chandrasekaran, S. R., Kunwar, B., Moser, B. R., Rajagopalan, N., and Sharma, B. K. (2015). Application of waste plastic pyrolysis oil in a direct injection diesel engine: For a small scale non-grid electrification. doi: 10.1002/bbb.1474, Demirbas, A. doi: 10.1016/j.joei.2016.11.005, Gebreslassie, B. H., Slivinsky, M., Wang, B., and You, F. (2013). Saudi natural zeolite (NZ), collected from Harrat-Shama located in the northwest of Jeddah city, KSA (Nizami et al., 2016), was modified by thermal and acid treatment and used in these catalytic pyrolysis experiments. (2004) used different kinds of catalysts and reported that even mixing of HZSM-5 with mesoporous SiO2-Al2O3 or MCM-41 led to the maximum production of liquid oil with minimal gas production. Kinetics and optimization. The studies were carried out to explore the potential of produced liquid oil in the context of engine performance and vehicle exhaust emission. 77, 18941901. Technol. doi: 10.1021/cs3003403, Shah, J., and Jan, M. R. (2015). Fuel Process. Volatile products of poly (ethylene terephthalate) thermal degradation in nitrogen atmosphere. Stab. doi: 10.1016/j.jcis.2017.10.029, Miandad, R., Nizami, A. S., Rehan, M., Barakat, M. A., Khan, M. I., Mustafa, A., et al. 1, 7484. FT-IR analysis of liquid oil produced from catalytic pyrolysis with TA-NZ. In recent years, NZ has gained significant attention for its potential environmental applications. Chem. Renew. In this study, modified NZ catalysts were added in the reactor with the feedstock. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Energy Eng. Stab. 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. Pyrolysis is a common technique used to convert plastic waste into energy, in the form of solid, liquid and gaseous fuels. (2016). doi: 10.1016/j.polymdegradstab.2004.06.001, Zeaiter, J. The liquid oil has a high heating value (HHV) range of 41.744.2 MJ/kg, close to conventional diesel. Pyrolysis studies of PP/PE/PS/PVC/HIPS-Br plastics mixed with PET and dehalogenation (Br, Cl) of the liquid products. Moreover, the presence of an acidic catalyst and free hydrogen atom may lead to alkylation of toluene and benzene, converting intermediate alkylated benzene to the production of naphthalene due to aromatization (Xue et al., 2017). Plastics are made of petrochemical hydrocarbons with additives such as flame-retardants, stabilizer, and oxidants that make it difficult to bio-degrade (Ma et al., 2017). Today 62, 6775. The activation process increased the BET surface area and reduced the pore size of the char (Lopez et al., 2009). However thermal pyrolysis of the only PE without a catalyst converted it into wax instead of liquid oil due to its strong long chain branched structure (Lee, 2012; Miandad et al., 2016b). However, microporous catalysts hinder the entrance of larger molecules and thus higher carbon chain compounds are produced from catalytic pyrolysis of PE with microporous catalysts. (2002) reported that PP degradation produces maximum gas in the presence of acid catalysts. Lopez et al. (2016) also reported the maximum production of gas from catalytic pyrolysis of PE, with highly acidic ZSM-5 catalyst. The obtained yield of each pyrolysis product was calculated based on weight, after the completion of each experiment. (2015) and Lee et al. J. Degrad. The quality and yield of pyrolysis products such as liquid oil, gas, and char were studied. doi: 10.1016/j.psep.2016.06.022, Miandad, R., Barakat, M. A., Rehan, M., Aburiazaiza, A. S., Ismail, I. M. I., and Nizami, A. S. (2017a). Several researchers activated the char via steam and thermal activation (Lopez et al., 2009; Heras et al., 2014). ThermalCatalytic cracking of real MSW into Bio-Crude Oil. Degrad. Dawood and Miura (2002) also reported the high production of these compounds from the catalytic pyrolysis of PP with a high acidic modified HY-zeolite. Int. Polym. (2018). doi: 10.1016/j.compchemeng.2012.10.013, Heras, F., Jimenez-Cordero, D., Gilarranz, M. A., Alonso-Morales, N., and Rodriguez, J. J. doi: 10.1016/B978-0-444-64017-8.00017-8. (1998) carried out catalytic pyrolysis of polyethylene (PE) with HZSM-5 catalysts. doi: 10.1080/15567036.2016.1153753, Rizzarelli, P., Rapisarda, M., Perna, S., Mirabella, E. F., La Carta, S., Puglisi, C., et al. Green Chem. Thilakaratne et al. In addition, the presence of the oxygen atom also favors the high production of char from catalytic pyrolysis of PET (Xue et al., 2017). 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. doi: 10.1016/j.polymdegradstab.2013.02.013, Dziecio, M., and Trzeszczynski, J. 1. Polym. Lopez et al. The NZ was modified by thermal activation (TA-NZ) at 550C and acid activation (AA-NZ) with HNO3, to enhance its catalytic properties. Catalytic pyrolysis of plastic waste: a review. 29, 273283. Liquid and gaseous fuel from waste plastics by sequential pyrolysis and catalytic reforming processes over indonesian natural zeolite catalysts. Degrad. Different kinds of catalysts are used to improve the pyrolysis process of plastic waste overall and to enhance process efficiency. J. Anal. Miskolczi et al. (2010) reported that the aromatic production from PP/PE catalytic pyrolysis might follow the DielsAlder reaction mechanism and is then followed by dehydrogenation. In addition, in the presence of acidic catalysts, due to carbenium mechanism, the formation of aromatic and olefin compound production may increase (Lee, 2012). J. Anal. Other aspects for optimization of pyrolysis based biorefineries, such as new emerging advanced catalysts including nano-catalysts, have to be developed and applied in pyrolysis processes in order to increase the quality and yield of products, and to optimize the overall process. 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.