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.

The purpose of this study is to determine the influence of the temperature and reaction time on the thermal pyrolysis process of compact polystyrene residues based on the percentage of liquid obtained at a heating cup of 15 C min-1 and cooling system for the condensation of pyrolytic gases at 10 ° C. It worked with temperatures between 375 and 425 °C and times of 5 and 10 minutes. The results showed that the reaction time has no representative influence on the liquid fraction, while the temperature has a great importance in the liquid yield reaching a maximum contribution at 400 °C, after this the percentage of liquid oils tends to decrease by guiding the formation of the gas fraction. The maximum production was 81.4% with a kinematic viscosity of 1,026 mm2 s-1, relative density 0.9352, flash point 24 °C and a caloric power of 48.5 MJ kg-1. The mixture of aromatic hydrocarbons obtained, with carbon chains between C6 and C20, are present in 75% by mass.

Modelado de la biodegradación en biorreactores de lodos de hidrocarburos totales del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)

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.

In the present study, the thermodynamic parameters of Polylactic Acid (PLA) under conditions of thermal degradation were determined. The PLA material, previously sampled and characterized, was analyzed by dynamic thermogravimetry (TG) at heating rates of 5, 10 and 15 °C min−1 with a nitrogen flow of 20 mL min−1 from a temperature of 25 to 900 °C. The data were treated using isoconversional kinetic models to obtain the activation energy and the pre-exponential factor of each model. To fit the DTG curves, the Arrhenius equation was used applying the Contraction Sphere reaction model: two-dimensional phase limit reaction (R2). The thermodynamic parameters such as enthalpy, Gibbs free energy and entropy were determined from the kinetic parameters of suitable models for each heating rate after statistical validation and comparison with other studies. The results showed that as the heating rate increases, the degradation temperature also increases, while the activation energy, enthalpy and pre-exponential factor decrease. According to the value of ∆G (171.65 kJ mol−1), PLA has a significant potential to be used as a raw material to produce bioenergy/biofuels by pyrolysis.

Esta investigación tuvo como objetivo estudiar las condiciones óptimas de pirólisis usando plástico de invernadero (LDPE) residual para obtener la mayor cantidad de ceras líquida. Para cada ensayo 100 g de plástico se alimentaron a un reactor batch con atmósfera inerte de nitrógeno y un sistema de refrigeración con agua (10°C) para la recolección de condensables. Para evaluar el efecto de la temperatura en el rendimiento del proceso se realizaron pruebas a cinco temperaturas entre 350–450°C, con una tasa de calentamiento de 13°C/min. A la fracción liquida obtenida se caracterizó por cromatografía de gases y se determinó propiedades como: gravedad API, punto de inflamación, poder calórico y contenido de azufre. El producto de pirólisis fue una cera oleosa compuesta por parafinas, naftenos y olefinas, de alto poder calorífico (46.49 MJ/Kg), relativamente limpia, capaz de ser utilizada para obtener combustibles refinados. La temperatura que genera mayor rendimiento (67.85%) de productos líquidos es de 400°C, con un tiempo de residencia de 6 min. Por lo que, se concluye que la pirólisis de LDPE genera una mezcla rica de hidrocarburos alifáticos (93.52%) a esa temperatura; mientras que temperaturas mas altas se favorece la formación de gases no condensables y ceras pesadas.

In many countries, Heavy Fuel Oil (HFO) is still a common fuel in industrial applications due to its low price and high energy density. However, the complex and incomplete combustion of HFO results in high levels of emissions and low efficiency, which causes the search for additives to improve its properties without affecting its heating value. The present paper aims to use as an additive the liquid fraction from pyrolysis of the polystyrene for fuel oil, replacing conventional additives such as cutter stock, improving its fluidity without using heat to pump it. As for pyrolysis for obtaining pyrolytic oil, the effect of temperature on the chemical composition of the liquid fraction from the thermal pyrolysis of compact polystyrene was studied. PS pyrolysis was carried out in a temperature range between 350 to 450 °C at a heating rate of 15 °C min−1 in a batch type reactor, with a condensation system, in order to analyze the best fraction liquid yield. At 400 °C we obtained a liquid fraction of 81%. This product presented a kinematic viscosity of 1.026 mm2 s−1, a relative density of 0.935, a flash point of 24 °C, and a gross heating value of 48.5 MJ kg−1. Chromatographic analysis indicates that 75% by mass of the components corresponds to C6 to C20 hydrocarbons, showing the high generation of isomers of the polystyrene monomer and aromatic compounds. The product obtained is mixed with base fuel oil at 60 °C at 250 rpm for a period of one hour, in percentages of 10 to 50% by mass. The 10% mixture has properties very close to those required by the standard fuel oil, presenting a viscosity of 108 mm2 s−1 that adjusts to the requirements in burners for industrial applications; additionally, it has a Sulphur content lower than that of fuel oil without affecting its heating value.

The increasing generation of plastic wastes forces us to search for final disposal technologies. Pyrolysis becomes an interesting technique in the last few years because it takes advantage of the wastes obtaining important products. Moreover, catalytic pyrolysis develops a great selectivity in the products so, the recovered of catalysts from other processes gain significant interest. In this study, we report the evaluation of the catalytic pyrolysis carried out in a batch reactor with a regenerated FCC catalyst using thermogravimetry (TGA). The regeneration studies were carried using two solvents (ethanol and toluene) at different contact times, then a thermal regeneration at two heating ramps was developed. The catalysts were characterized by SEM-EDS and BET, then used to compare with a commercial catalyst in the pyrolysis process in a 1:10 ratio (catalyst-plastic). The catalytic pyrolysis of polypropylene (PP) was carried out at 450 °C, and the products were quantified. The results showed a better solvent action of the ethanol in 14 hours of contact and longer gasification. The degradation process using recovered catalyst decreases the degradation temperature compared to the no-catalyst process. As a consequence, the yield of the liquid fraction decreases by 10% with greater orientation to aliphatic components.