The use of plastic as material in various applications has been essential in the evolution of the technology industry and human society since 1950. Therefore, their production and waste generation are high due to population growth. Pyrolysis is an effective recycling method for treating plastic waste because it can recover valuable products for the chemical and petrochemical industry. This work addresses the thermal pyrolysis of expanded polystyrene (EPS) post-industrial waste in a semi-batch reactor. The influence of reaction temperature (350–500 °C) and heating rate (4–40 °C min⁻¹) on the liquid conversion yields and physicochemical properties was studied based on a multilevel factorial statistical analysis. In addition, the analysis of the obtaining of mono-aromatics such as styrene, toluene, benzene, ethylbenzene, and α-methyl styrene was performed. Hydrocarbon liquid yields of 76.5–93% were achieved at reaction temperatures between 350 and 450 °C, respectively. Styrene yields reached up to 72% at 450 °C and a heating rate of 25 °C min⁻¹. Finally, the potential application of the products obtained is discussed by proposing the minimization of EPS waste via pyrolysis.

Effects of heating rate and temperature on thermal-pyrolytic yield of a plastic-waste mixture were studied in a semi-batch reactor. The temperature in the range of 380–460 °C and heating rates of 10, 19, and 28 °C/min were evaluated through an experimental multi-level design. The results show that higher temperatures or lower residence time reduce the yield of pyrolytic oil at the expense of increasing the yield of gaseous products. The maximum liquid yield was 69%, obtained at 410 °C and a heating rate of 10 °C/min. The composition of pyrolytic oil covers a wide range of hydrocarbons; thus, a fractionation is necessary before using it as fuel in internal combustion engines. The fractionation process yielded 21.12 wt% of light fraction (gasoline-like), 56.52 wt% of medium fraction (diesel-like), and 22.36 wt% of heavy fraction (heavy diesel-like). The light fraction has an octane index and caloric value within the range of the typical gasoline values. On the other hand, the cetane index and caloric value of the medium fraction meet the requirements of the standards for diesel.

Pyrolysis of plastic waste generates alternative fuels that are useful for thermal devices. However, it is the subsequent fractionation process that truly distinguishes itself, refining these fuels to a quality comparable to petroleum derivatives such as diesel and gasoline, thereby making them suitable for direct use in internal combustion engines. This study evaluated the effect on emissions of an internal combustion engine fueled with waste plastic oil diesel-like fuel and its blend with biodiesel. The tests were conducted on-road using a typical light-duty diesel vehicle for passenger or courier transportation. Three tests were carried out, the first one with petroleum diesel (D100) as the reference fuel, the second one with waste plastic oil diesel-like fuel (WPO-DL), and the last with a blend of 80% WPO-DL and 20% biodiesel obtained from waste cooking oil (WPO-DL80WCO20). The main findings were a reduction in the generation of NOx when using WPO-DL. However, using WPO-DL increased the production of CO and HC, attributed to the presence of more heavy hydrocarbons compared to that of D100. Additionally, for the WPO-DL80WCO20 blend under acceleration conditions HC decreased under all acceleration conditions. These findings demonstrate that the distilled fuel obtained from the pyrolytic oil product of non-recyclable plastic waste by conventional methods would contribute to the global energy transition and reduce the presence of tons of non-recyclable plastic waste by traditional methods.

This work presents a polynomial regression model for the optimization of the content of fatty acid methyl esters and the conversion yield of waste vegetable oil to biodiesel. The equations are optimized to obtain the maximum fatty acid methyl esters yield, which is the product of the conversion yield and the fatty acid methyl esters content in the biodiesel. The independent variables considered are the type of catalyst used (KOH and NaOH), percentage of catalyst (0.6%, 1.0%, and 1.5% w/w with respect to oil), and the methanol: oil molar ratio (6:1, 7.5:1, and 9:1). The prediction models are obtained by using nine experimental points for each catalyst. The validation is developed with four main experimental points from the mapping. A polynomial relation is obtained as a consequence, which correlates each of the experimental variables with the fatty acid methyl esters and conversion yield. The optimization of the proposed models shows an error of 2.66% for the fatty acid methyl esters, and an error of less than 1% for the conversion yield are obtained. This work presents a straight forward methodology to obtain the best chemical conditions in the production of biodiesel by using a small number of experiments, obtaining good results. This methodology can be applied for biodiesel production from any raw material, recalculating each of the regression constants thus allowing to obtain the highest quantity of oil to be converted in fatty acid methyl esters.

Los ácidos grasos provienen de múltiples aceites animales y vegetales, donde este es el principal reactivo para la producción de biodiésel y representa cerca del 80% de su costo comercial. Adicional se requiere de un alcohol de cadena corta como etanol y metanol, también de catalizadores para producir la reacción de transesterificación por la cual se obtienen ésteres (biodiésel). Los ácidos grasos varían dependiendo de su origen, comúnmente en cadenas de doce a veinte carbonos y en su mayor proporción se encuentran el ácido palmítico (C16) y los ácidos oleicos (C18). Existe una mayor afinidad de algunos ácidos grasos con el alcohol en reacción, la cual depende de múltiples parámetros como agitación, calentamiento y contacto entre estas dos sustancias inmiscibles en reacción. Este trabajo presenta la producción, caracterización y afinidad del biodiésel producido de dos materias primas de origen animal bajo una relación molar metanol:aceite de 6:1 e hidróxido de potasio (KOH) como catalizador al 1.5 %. La caracterización del biodiésel se desarrolla de acuerdo con la UNE-EN 14214 determinando el FAME (Fatty Acid Methyl Esters) por cromatografía de gases, densidad, viscosidad y poder calorífico de cada una de las materias primas seleccionadas.