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.

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.