Fuel production from waste polystyrene via pyrolysis: Kinetics and products distribution

A review on value-addition to plastic waste towards achieving a circular economy

Plastic and mixed plastic waste (PW) has received increased worldwide attention owing to its huge rate of production, high persistency in the environment, and unsustainable waste management practices. Therefore, sustainable PW management and upcycling approaches are imperative to achieve the objectives of the United Nations Sustainable Development Goals. Numerous recent studies have shown the application and feasibility of various PW conversion techniques to produce materials with better economic value. Within this framework, the current review provides an in-depth analysis of cutting-edge thermochemical technologies such as pyrolysis, gasification, carbonization, and photocatalysis that can be used to value plastic and mixed PW in order to produce energy and industrial chemicals. Additionally, a thorough examination of the environmental impacts of contemporary PW upcycling techniques and their commercial feasibility through life cycle assessment (LCA) and techno-economical assessment are provided in this review. Finally, this review emphasizes the opportunities and challenges accompanying with existing PW upcycling techniques and deliver recommendations for future research works.

Global trends of pyrolysis research: a bibliometric analysis

Pyrolysis has become an interesting waste valorization method leading to an increasing number of research studies in this field in the last decade. The present study aims to provide a comprehensive knowledge map of scientific production in pyrolysis, discuss the current state of research, and identify the main research hotspots and trends in recent years. The systematic review, supported by analysis of countries and institutions, keyword co-occurrence analysis, analysis of keyword trends, journal analysis, and article impact, was carried out on 6234 journal articles from the Science Citation Index Expanded database of the Web of Science Core Collection. As a result, four main research hotspots were identified: 1) characterization techniques and pyrolysis kinetic models, 2) biochar production and its main applications, 3) bio-oil production and catalytic pyrolysis, and 4) co-pyrolysis, which has become a consolidated research hotspot since 2018. Additionally, the main challenges and opportunities for future research have been identified, such as 1) the development of multi-step kinetic models for studying complex wastes, 2) the integration of biochar into other valorization processes, such as anaerobic digestion, and 3) the development of catalytic hydropyrolysis for the valorization of organic waste. This bibliometric analysis provides a visualization of the current context and future trends in pyrolysis, facilitating future collaborative research and knowledge exchange.

Effects of ZSM-5 zeolite on pyrolysis of polystyrene: from stabilizing to catalyzing

Nonisothermal pyrolysis measurements of polystyrene (PS)/ZSM-5 zeolite hybrids are conducted in N2 and thermogravimetric results have been kinetically analyzed with different isoconversional methods. Experimental results show that the addition of 5 and 10 wt.% ZSM-5 zeolite has increased the initial pyrolysis temperature of PS while the addition of 20 and 30 wt.% ZSM-5 zeolite can significantly decrease the initial pyrolysis temperature of PS. Elevated activation energy is resulted by adding low zeolite amount whereas reduced activation energy is obtained by adding high ZSM-5 amounts. The effect of zeolite ZSM-5 on PS pyrolysis can thus be observed to transfer from stabilizing to catalyzing. Furthermore, the pyrolysis mechanism functions of PS/zeolite hybrids are determined by integrating the master plots method with a new compensation effect method, and the most appropriate reaction models are found to be F0.92, F0.85, F0.56 and A1.32 for describing the pyrolysis of the PS/ZSM-5 hybrids with a zeolite loading of 5, 10, 20 and 30 wt.%, respectively. With the kinetic parameters thus available, the temperature-dependent mass conversion curves have been recast, leading to satisfactory simulations for PS/ZSM-5 hybrids.

Co-Pyrolysis for Pine Sawdust with Potassium Chloride: Insight into Interactions and Assisting Biochar Graphitization

This effort aimed to explore the activation and catalytic graphitization mechanisms of non-toxic salts in converting biomass to biochar from the perspective of pyrolysis kinetics using renewable biomass as feedstock. Consequently, thermogravimetric analysis (TGA) was used to monitor the thermal behaviors of the pine sawdust (PS) and PS/KCl blends. The model-free integration methods and master plots were used to obtain the activation energy (E) values and reaction models, respectively. Further, the pre-exponential factor (A), enthalpy (ΔH), Gibbs free energy (ΔG), entropy (ΔS), and graphitization were evaluated. When the KCl content was above 50%, the presence of KCl decreased the resistance to biochar deposition. In addition, the differences in the dominant reaction mechanisms of the samples were not significant at low (α ≤ 0.5) and high (α ≥ 0.5) conversion rates. Interestingly, the lnA value showed a linearly positive correlation with the E values. The PS and PS/KCl blends possessed positive ΔG and ΔH values, and KCl was able to assist biochar graphitization. Encouragingly, the co-pyrolysis of the PS/KCl blends allows us to target-tune the yield of the three-phase product during biomass pyrolysis.

Fixed Bed Batch Slow Pyrolysis Process for Polystyrene Waste Recycling

This study evaluates the potential of recycling polystyrene (PS) plastic wastes via a fixed bed (batch) slow pyrolysis reactor. The novelty lies in examining the reactor design, conversion parameters, and reaction kinetics to improve the process yield, activation energy, and chemical composition. PS samples were pyrolyzed at 475–575 °C for 30 min under 10–15 psi. Process yield and product attributes were evaluated using different methods to understand PS thermal degradation characteristics better. The results show that PS decomposition started within 2 min from all temperatures, and the total decomposition point of 97% at 475 °C at approximately 5 min. Additionally, analytical results indicate that the average necessary activation energy is 191 kJ/mol. Pyrolysis oil from PS was characterized by gas chromatography–mass spectrometry. The results show that styrene was produced 57–60% from all leading oil compounds (i.e., 2,4-diphenyl-1-butene, 2,4,6-triphenyl-1-hexene, and toluene), and 475 °C has the major average of conversion effectiveness of 91.3%. The results show that the reactor temperature remains the main conversion parameter to achieve the high process yield for oil production from PS. It is concluded that pyrolysis provides a sustainable pathway for PS waste recycling and conversion to value-added products, such as resins and polymers. The proposed method and analytical results are compared with earlier studies to identify directions for future studies.

A Thermo-Catalytic Pyrolysis of Polystyrene Waste Review: A Systematic, Statistical, and Bibliometric Approach

Global polystyrene (PS) production has been influenced by the lightness and heat resistance this material offers in different applications, such as construction and packaging. However, population growth and the lack of PS recycling lead to a large waste generation, affecting the environment. Pyrolysis has been recognized as an effective recycling method, converting PS waste into valuable products in the chemical industry. The present work addresses a systematic, bibliometric, and statistical analysis of results carried out from 2015 to 2022, making an extensive critique of the most influential operation parameters in the thermo-catalytic pyrolysis of PS and its waste. The systematic study showed that the conversion of PS into a liquid with high aromatic content (84.75% of styrene) can be achieved by pyrolysis. Discussion of PS as fuel is described compared to commercial fuels. In addition, PS favors the production of liquid fuel when subjected to co-pyrolysis with biomass, improving its properties such as viscosity and energy content. A statistical analysis of the data compilation was also discussed, evaluating the influence of temperature, reactor design, and catalysts on product yield.

Pyrolysis and combustion characteristics of typical waste thermal insulation materials

Thermal insulation materials are important for building energy conservation, but their wastes have increased sharply. Furthermore, pyrolysis and combustion are increasingly utilized to dispose of solid wastes and convert them into value-added fuels. To better understand the pyrolysis and combustion characteristics of these materials, typical thermal insulation materials (expanded polystyrene (EPS) and extruded polystyrene (XPS)) were investigated by employing thermogravimetry and differential scanning calorimetry as well as cone calorimetry experiments. Pyrolysis behavior, kinetic parameters, pyrolysis index, thermodynamic parameters, endothermic properties and combustion parameters were estimated comprehensively. The results showed that EPS had better pyrolysis properties, while XPS had better combustion characteristics. Activation energies of EPS and XPS were 158.82 kJ/mol and 200.70 kJ/mol, respectively. Additionally, EPS had a higher pyrolysis stability index and comprehensive pyrolysis index, meaning a more intense reaction. Moreover, thermodynamic parameters indicated that the devolatilization products could be obtained easily from the two materials, and EPS and XPS could be converted into fuels. For the combustion, XPS had a smaller fire performance index and a larger fire growth index. These results can guide the reactor design and optimization for better converting polymer wastes into fuels and managing wastes.

Polypropylene pyrolysis kinetics under isothermal and non-isothermal conditions: a comparative analysis

The kinetics of polypropylene pyrolysis has been studied under isothermal and non-isothermal conditions using Arrhenius and Kissinger–Akahira–Sunose (KAS) equations. Under isothermal conditions, applying first order kinetic model, activation energy (Ea) and pre-exponential factor (A) were investigated and observed as 119.7 kJ mol−1 and 1.2 × 1010 min−1, while in case of non-isothermal kinetics using Kissinger–Akahira–Sunose method, the average Ea and A were found to be 91.23 kJ mol−1 and 2.3 × 107 min−1, respectively. A comparison among the isothermal and non-isothermal reactions was made on the basis of kinetics parameters. The results from both the methods showed trivial variation in kinetic parameters of the pyrolysis reaction which may be due to two major reasons. Firstly, the selection of the kinetic model applied and secondly the inconsistency due to various experimental conditions used which can be reduced at optimized conditions. As the disposal of plastic materials need reliable kinetics information to model their decomposition reactions, therefore, the kinetics data thus obtained from pyrolysis reaction of model polypropylene will help in the utilization of polypropylene waste as energy source on industrial scale.

Production and Analysis of the Physicochemical Properties of the Pyrolytic Oil Obtained from Pyrolysis of Different Thermoplastics and Plastic Mixtures

The constant search for the proper management of non-degradable waste in conjunction with the circular economy makes the thermal pyrolysis of plastics an important technique for obtaining products with industrial interest. The present study aims to produce pyrolytic oil from thermoplastics and their different mixtures in order to determine the best performance between these and different mixtures, as well as to characterize the liquid fraction obtained to analyze its use based on said properties. This was carried out in a batch type reactor at a temperature of 400 °C for both individual plastics and their mixtures, from which the yields of the different fractions are obtained. The liquid fraction of interest is characterized by gas chromatography and its properties are characterized by ASTM standards. The product of the pyrolysis of mixtures of 75% polystyrene and 25% polypropylene presents a yield of 82%, being the highest, with a viscosity of 1.12 cSt and a calorific power of 42.5 MJ/kg, which has a composition of compounds of carbon chains ranging between C6 and C20, for which it is proposed as a good additive agent to conventional fuels for industrial use.

Production and Characterization of Maximum Liquid Oil Products through Individual and Copyrolysis of Pressed Neem Oil Cake and Waste Thermocol Mixture

In this study, individual and copyrolysis experiments were performed with pressed neem oil cake (NOC) and waste thermocol (WT) to produce high grade liquid oil. The effects of reactor temperature, heating rate, feed ratio, and reaction time on product yields were investigated to identify the optimum parameters for maximum oil yield. The maximum oil yield of 49.3 wt%, 73.4 wt% and 88.5 wt% was obtained from NOC pyrolysis, copyrolysis, and WT pyrolysis under optimized conditions. During copyrolysis, the maximum oil product was obtained under NOC/WT ratio of 1 : 2 and at the temperature of 550°C. The liquid oils obtained from thermal and copyrolysis were subjected to detailed physicochemical analysis. When compared to biomass pyrolysis, the copyrolysis of WT and NOC had a substantial improvement in oil properties. The copyrolysis oil shows higher heating value of 40.3 MJ/kg with reduced water content. In addition to that, the copyrolysis oil obtained under optimized conditions is analyzed with Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography–mass spectrometry (GC-MS) analysis to determine the chemical characterization. The analysis showed the presence of aliphatic and aromatic hydrocarbons in the oil.

Determination of the Thermodynamic Parameters of the Pyrolysis Process of Post-Consumption Thermoplastics by Non-Isothermal Thermogravimetric Analysis

Currently, the pyrolysis process is an important technology for the final treatment of plastic waste worldwide. For this reason, knowing in detail the chemical process and the thermodynamics that accompany cracking reactions is of utmost importance. The present study aims to determine the thermodynamic parameters of the degradation process of conventional thermoplastics (polystyrene (PS), polyethylene terephthalate (PET), high-density polyethylene (HDPE), polypropylene (PP) and polyvinyl chloride (PVC)) from the study of their chemical kinetics by thermogravimetric analysis (TG). Non-isothermal thermogravimetry was performed at three heating rates from room temperature to 550 °C with an inert nitrogen atmosphere with a flow of 20 mL min⁻¹. Once the TG data is obtained, an analysis is carried out with the isoconversional models of Friedman (FR), Kissinger–Akahira–Sunose (KAS), and Flynn–Wall–Ozawa (FWO) in order to determine the one that best fits the experimental data, and with this, the calculation of the activation energy and the pre-exponential factor is performed. The validation of the model was carried out using the correlation factor, determining that the KAS model is the one that best adjusts for the post-consumer thermoplastic degradation process at the three heating rates. With the use of the kinetic parameters, the variation of the Gibbs free energy is determined in each of the cases, where it is necessary that for structures containing aromatic groups a lower energy is presented, which implies a relative ease of degradation compared to the linear structures.

Kinetic study of the pyrolysis of polypropylene over natural clay

Clay is widely used in numerous industrial activities; however, its application as an efficient catalyst for the decomposition of plastic waste on a commercial scale is scanty. Therefore, in this study, we have made efforts to use natural clay as the catalyst for the thermal decomposition of polypropylene in a pyrolysis setup. The pyrolysis oil obtained was found rich in hydrocarbons ranging from C8–C35. Kinetics of the pyrolysis reaction was determined utilizing thermogravimetric data and the activation energy (E) and A-factor were observed as 70.33–94.80 kJ/mol and 6 × 105–2.3 × 108 min−1 using the Ozawa-Flynn-Wall method and 58.19–74.82 kJ/mol and 4.1 × 102–4.2 × 103 min−1 applying Tang Wanjun equation. The activation energy was found to increase with enhancement in conversion presenting a complex decomposition reaction. Comparing the activation energy determined in this work with previous studies confirmed that natural clay has reduced E of decomposition reaction at high fraction conversion. The pyrolysis results supported with the kinetic investigation in this work would have potential applications in disposing of plastic waste on an industrial scale and a step forward in the field of waste management.

Thermal behaviour and kinetic study of co-pyrolysis of microalgae with different plastics

The coexistence of plastics and microalgae in the ocean has brought great challenges to the environment. Therefore, co-pyrolysis of microalgae Dunaliella salina (DS) and typical plastics (polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC)) were investigated using thermogravimetric analyzer with Fourier transform infrared spectrometer. The results showed that the coating effect of the molten plastics promoted the pyrolysis of DS. The solid residue amounts of DS-PP, DS-PS, and DS-PET blends were reduced by 1.55 wt%, 1.39 wt%, 1.69 wt%, respectively, as a result of the hydrogenation reaction between the unsaturated products generated by plastics and biochar. While for DS-PVC, attributed to the physical and chemical effects during the co-pyrolysis process, the solid residue was increased by 1.36 wt%. For the other three blends, the solid residues were reduced due to the hydrogenation reaction between the unsaturated products generated by plastics and biochar. FTIR analysis of gaseous products indicated the total CO₂ production increased significantly for DS-PET. Besides, the alkyls generated by DS reacted with HCl during DS-PVC co-pyrolysis, the resulting products were then fixed in biochar. Kinetic results suggested that due to the co-pyrolysis with DS, the activation energies of PP, PS, and PET were reduced by 1/2, 1/3, and 3/4, respectively, and this value for PVC in its second stage was reduced by 1/4. Our results indicated the advantage to co-pyrolyze the microalgae and marine plastics.

Pyrolysis of waste expanded polystyrene and reduction of styrene via in-situ multiphase pyrolysis of product oil for the production of fuel range hydrocarbons

Upgraded fuel oil was produced from the waste expanded polystyrene (WEPS) using pyrolysis and in-situ selective aromatization in a specially designed reactor. The catalytic pyrolysis of WEPS was performed keeping the catalyst in three different types of catalyst arrangements inside the reactor i.e., A-type/catalyst in liquid phase, B-type/catalyst in vapour phase, and AB-type or Multiphase/catalyst in both liquid and vapour phases, respectively. The ZSM-5 ammonium powder was used as a catalyst with varying feed to catalyst ratio and 20:1 was found to be optimum. Aromatics of fuel range like benzene, toluene, and ethylbenzene (BTE) were significantly increased and styrene got reduced by many folds when AB-type/multiphase catalytic pyrolysis was performed. The thermal pyrolysis produced maximum liquid yield of 94.37 wt% at a temperature of 650 °C and a heating rate of 15 °C/min. The maximum liquid yield of 88.05 wt%, 78.85 wt%, and 75.11 wt% were obtained for the A-type, B-type, and AB-type catalytic pyrolysis at the temperature of 600 °C, 550 °C and 550 °C, respectively using the same heating rate. The liquid oil of thermal pyrolysis contains very low amount of fuel range aromatics i.e., BTE of 11.38 wt% and the highest amount of styrene (84.74 wt%). In contrarily, BTE content for the catalytic process increased progressively in the order of 18.98 wt% (A-type) < 24.27 wt% (B-type) < 28.12 wt% (AB-type). The styrene content significantly decreased to a very low value of 46.30 wt% for AB-type/multiphase pyrolysis at the temperature of 550 °C.

Chemical recycling of plastic waste: Bitumen, solvents, and polystyrene from pyrolysis oil

As an alternative to conventional plastic-waste treatments, herein, we report a pyrolytic plastic-recovery process in which diverse compounds and materials are recovered from the pyrolysis oil obtained from the plastic waste. Distillation of the pyrolysis oil led to a bitumen and a distilled fraction. The composition of the bitumen, as determined by saturate, aromatic, resin, and asphaltene (S.A.R.A.) analysis and corroborated by Fourier-transform infrared (FTIR) spectroscopy, was found to principally contain aromatics (55.05 wt%) and saturates (33.41 wt%), and has great potential as a modifier for bitumen mixtures by decreasing the viscosities or softening points of final products. The distilled fraction was characterised and compared to pyrolysis oil in terms of its physicochemical properties and composition. Analysis by gas-chromatography/mass-spectrometry (GC-MS) revealed high levels of aromatics, namely styrene, benzene, toluene, ethylbenzene, and α-methylstyrene, which are potentially recoverable base compounds for industrial use. With this in mind, the distillate was subjected to various processes, including aromatic extraction with sulfolane and subsequent fractional distillation to recover the principal compounds in the various GC-MS fractions. Fraction 1 was found to be rich in ethylbenzene and toluene, while fraction 2 contained 73.26 wt% styrene and was used to synthesise recycled polystyrene (PS), whose yield and molecular weight (M_w) were optimised by adjusting the initiator concentration, temperature, and time. The optimised recycled PS was characterised to provide a yield of 77.64% and a M_w higher than 53,000 g/mol; this recycled PS exhibited similar thermal properties to those of conventional PS prepared using petrochemical sources.

Pyrolysis of polystyrene waste for recovery of combustible hydrocarbons using copper oxide as catalyst

The present work is focused on pyrolysis of polystyrene waste for production of combustible hydrocarbons. The experiments were performed in an indigenously made furnace in the presence of a laboratory synthesised copper oxide. The pyrolysis products were collected and characterised. The Fourier transform infrared spectra showed that the liquid fraction contains C-H, C-O, C-C, C=C and O-H bonds, which correspond to various aliphatic and aromatic compounds. Gas chromatography-mass spectrometry traced compounds ranging from C₁ to C₄ in the gaseous fraction, whereas in the liquid fraction 15 components ranging from C₃ to C₂₄ were detected. From the results it has been concluded that CuO as a catalyst not only increased the liquid yield but also reduced the degradation temperature to great extent. Fuel properties of the pyrolysis oil were determined and compared with standard values of commercial fuel oil. The comparison suggested potential application of pyrolysis oil for domestic and commercial use.

Energy Utilization of Building Insulation Waste Expanded Polystyrene: Pyrolysis Kinetic Estimation by a New Comprehensive Method

Expanded polystyrene (EPS) has excellent thermal insulation properties and is widely applied in building energy conservation. However, these thermal insulation materials have caused numerous fires because of flammability. Pyrolysis is necessary to support combustion, and more attention should be paid to the pyrolysis characteristics of EPS. Moreover, pyrolysis is considered to be an effective method for recycling solid waste. Pyrolysis kinetics of EPS were analyzed by thermogravimetric experiments, both in nitrogen and air atmospheres. A new method was proposed to couple the Flynn–Wall–Ozawa model-free method and the model-fitting method called the Coats–Redfern as well as the particle swarm optimization (PSO) global algorithm to establish reaction mechanisms and their corresponding kinetic parameters. It was found that the pyrolysis temperature of EPS was concentrated at 525–800 K. The activation energy of EPS in nitrogen was about 163 kJ/mol, which was higher than that in air (109.63 kJ/mol). Furthermore, coupled with Coats–Redfern method, reaction functions g(α) = 1 − (1 − α)³ and g(α) = 1 − (1 − α)^1/4 should be responsible for nitrogen and air reactions, respectively. The PSO algorithm was applied to compute detailed pyrolysis kinetic parameters. Kinetic parameters could be used in further large-scale fire simulation and provide guidance for reactor design.

Kinetic and volatile products study of micron-sized PMMA waste pyrolysis using thermogravimetry and Fourier transform infrared analysis

Much attention has been devoted to disposing traditional-sized poly(methyl methacrylate) (PMMA) waste by pyrolysis for methyl methacrylate (MMA). The pyrolysis of micron-sized PMMA waste, which may be different from that of traditional-sized PMMA waste, received little concern. The present study investigated the kinetics and volatile products of micron-sized PMMA waste pyrolysis in inert atmosphere using thermogravimetry and Fourier transform infrared analysis. A global optimization algorithm namely Shuffled Complex Evolution (SCE) was employed to simultaneously optimize the kinetic parameters. Results indicated that one shoulder and one peak occurred in the MLR variations with temperature. The values of the MLR at the shoulder and peak, the average MLR all increased with the heating rate. The optimized kinetic parameters by SCE can be utilized to well reproduce the experimental thermogravimetric data. The values of activation energy and natural logarithm of pre-exponential factor were in the range of 235.95-248.61 kJ/mol and 16.96-28.76 min^-1, respectively. The value of activation energy of micron-sized PMMA waste pyrolysis under the present study was greater than that of the traditional-sized PMMA pyrolysis in the previous studies. MMA and CO₂ were the major volatile products generated from the micron-sized PMMA waste pyrolysis. The volatile products yield at peak was much larger than that at shoulder. The MMA and CO₂ yield were in the range of 87.98-93.54% and 6.46-12.02%, respectively. High MMA yield may be obtained from the pyrolysis of micron-sized PMMA waste in inert atmosphere by appropriately increasing the heating rate adopted in the reactors in the practical applications.

Pyrolytic degradation of peanut shell: Activation energy dependence on the conversion

This study focuses on the thermo-kinetic analysis of solid peanut shell waste, through dependence of the activation energy with the conversion degree. Three model-free kinetics, Kissinger (K), Friedman (Fr) and Kissinger-Akahira-Sunose (KAS), were applied to thermogravimetric (TGA) data to calculate the effective activation energy E_α during a pyrolysis process. The results obtained by Kissinger's method showed that the pyrolytic breakdown pathway of hemicellulose, cellulose, and lignin in a ligno-cellulosic biomass is independent of the heating rate and can be described through a simple first-order kinetic reaction (f(α) = 1 - α). The thermo-kinetic behavior obtained by isoconversional methods (Fr and KAS) of the hemicellulose degradation shows a progressive and monotonic increase in E_α with the conversion, between ~140 and ~195 kJ mol^-1 with an average value of 172 kJ mol^-1, which reveals the competitive character of the process (multi-step process). Conversely, in the cellulose degradation, the dependence of E_α on α, shows the typical behavior of a reaction controlled by a single rate-determining step, with constant average E_α values of ~209 kJ mol^-1. Meanwhile, the lignin pyrolytic degradation shows an increase in E_α from ~220 up to ~300 kJ mol^-1 with the conversion, indicating that this stage is kinetically controlled by an energy barrier that comprises multiple and simultaneous processes. Finally, the kinetic analysis confirmed the absence of autocatalytic reactions (thermally auto-catalyzed process) during the pyrolysis, although the global process is highly exothermic.

Thermo-catalytic decomposition of polystyrene waste: Comparative analysis using different kinetic models

Due to a huge increase in polymer production, a tremendous increase in municipal solid waste is observed. Every year the existing landfills for disposal of waste polymers decrease and the effective recycling techniques for waste polymers are getting more and more important. In this work pyrolysis of waste polystyrene was performed in the presence of a laboratory synthesized copper oxide. The samples were pyrolyzed at different heating rates that is, 5°Cmin^-1, 10°Cmin^-1, 15°Cmin^-1 and 20°Cmin^-1 in a thermogravimetric analyzer in inert atmosphere using nitrogen. Thermogravimetric data were interpreted using various model fitting (Coats-Redfern) and model free methods (Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose and Friedman). Thermodynamic parameters for the reaction were also determined. The activation energy calculated applying Coats-Redfern, Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose and Friedman models were found in the ranges 105-148.48 kJmol^-1, 99.41-140.52 kJmol^-1, 103.67-149.15 kJmol^-1 and 99.93-141.25 kJmol^-1, respectively. The lowest activation energy for polystyrene degradation in the presence of copper oxide indicates the suitability of catalyst for the decomposition reaction to take place at lower temperature. Moreover, the obtained kinetics and thermodynamic parameters would be very helpful in determining the reaction mechanism of the solid waste in a real system.

Pyrolysis of polypropylene over zeolite mordenite ammonium: kinetics and products distribution

The present work reveals pyrolysis kinetics of polypropylene (PP) over zeolite modernite using thermogravimetry. The activation energy (Ea) and frequency factor (A) were calculated applying Ozawa Flynn Wall, Coats-Redfern, and Tang Wanjun methods. The Ea calculated by all the methods were found in accord with each other. The pyrolysis was also performed in a salt bath in the temperature range 350°C–390°C. It was observed that a temperature of 370°C is the optimum temperature for maximum liquid fuel production. Moreover, the amount of solid residue decreases with the rise in temperature. Similarly, gas fraction also shows linear relationship with temperature. The condensable and noncondensable fractions were collected and analyzed by gas chromatography-mass spectrometry. The fuel properties of the oil produced were assessed and compared with commercial fuel. These properties agree well with fossil fuel and therefore have potential applications as fuel.