Pyrolysis is a promising technology for the valorisation of plastic waste by converting it into valuable products, such as fuels and chemicals. This study aims to assess the thermogravimetric behaviour and kinetic parameters of the real-world plastic waste mixture with added nickel-and iron-based catalysts on gamma-aluminium oxide as support. Thermogravimetric measurements were carried out in a nitrogen atmosphere over a set of heating rates (5, 10, 15 and 20 °C/min) within a temperature range 40-600 °C. Kinetic analysis was performed through a combined approach by using the model-free isoconversional Friedman method and regression methods (linear and multivariate nonlinear). The kinetic analysis results showed a complex decomposition mechanism of the real-world plastic waste mixture. The average apparent activation energy for the real-world plastic waste mixture (22% high-density polyethylene, 31% low-density polyethylene, 35% polypropylene, 12% polystyrene) was 205 kJ/mol. The initial value decreased by 15.6% with the addition of iron-based gamma-aluminium oxide catalyst and only 9.8% with nickel-based gamma-aluminium oxide catalyst.
Pyrolysis is gaining more significance as a technology used to produce alternative fuels and chemicals. This study dealt with the catalytic pyrolysis of a realistic waste mixture of multi-layered plastic food packaging. The thermal behavior, kinetic parameters, and kinetic model of multi-layered plastic food packaging pyrolysis were determined to show its potential for process scale-up. In particular, we aimed to evaluate the effect of a ZSM-5 zeolite catalyst, modified with iron(III) oxide. The pyrolysis process on this decagonal structure was investigated using thermogravimetric analysis under nitrogen flow at four heating rates ranging between 40 and 600 °C. The kinetic study was conducted using the model-free isoconversional Friedman method as well as advanced statistical analysis to determine the reaction mechanism of the process. The thermal decomposition occurred in the range of 350–510 °C, with a mass loss greater than 90%. The kinetic study revealed a complex pyrolysis process, which consisted of three decomposition stages, diffusion, and Avrami-Erofeev reaction types. The activation energy values determined by the Friedman method rose with the degree of conversion, from 127 kJ mol−1 at 0.01 to 219 kJ mol−1 at 0.95. The doping of the catalyst lowered the activation energy of the reaction by 44% and 8% in the first and second stages, respectively, and increased the acidity of the zeolites, thus enhancing the reactivity on the surface of the catalysts. Lower activation energy meant less energy was required to heat the pyrolysis reactor since the onset temperature of sample decomposition was reduced.
Waste management systems are modelled to provide a public waste management service and need to be able to meet environmental sustainability requirements at a cost that is acceptable to system users/citizens. Overall environmental, economic, and/or socio-economic sustainability of waste management in previous publications is done through independent analyses and comparisons of obtained results or through multicriterial ranking of different alternatives where final results do not have a meaningful physical significance and cannot be interpreted independently. At the same time, those analysis either neglect time dependant changes by focusing on moment in time, or take into account changes in some timeframe changes but report only ranking focused single-score results, thus, results neglect time-dependent developments. All of these approaches are lacking some information needed for informed decision-making and/or are difficult to understand by wider groups of people. Thus, in this study, link between economic and environmental sustainability is analysed through newly defined single-score Economic Efficiency of Resource Recovery (EERR) index that shows the specific system cost for achieving identified resource recovery, while legislation based time dependent changes are taken into account through successive analyses for legislative most important years. This approach can be used for benchmarking the overall (environmental and economic) sustainability trends, while its graphical representation enables easier presentation of sustainability results and can be used for easier comparison of possible solutions and decisionmaking. The results show that the quality decision-making process needs to take into account the impact of expected changes on overall sustainability and evaluate how they will affect the actual perception of used technologies. In this context, it is shown that overall changes in sustainability, in comparison to the existing perception, can significantly change, depending on which technologies the system is based on.
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