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In this work, the low-temperature pyrolysis of a real plastic mixture sample collected at a WEEE-authorised recycling facility has been investigated. The sample was pyrolysed in a batch reactor in different temperature and residence time conditions and auto-generated pressure by following a factorial design, with the objective of maximising the liquid (oil) fraction. Furthermore, the main polymers constituting the real sample were also pyrolysed in order to understand their role in the generation of oil. The pyrolysis oils were characterised and compared with commercial fuel oil number 6. The results showed that in comparison to commercial fuel oil, pyrolysis oils coming from WEEE plastic waste had similar heating values, were lighter and less viscous and presented similar toxicity profiles in fumes of combustion. [ABSTRACT FROM AUTHOR]

The aim of this paper is for the production of oils processed in refineries to come from the pyrolysis of real waste from the high plastic content rejected by the recycling industry of the Basque Country (Spain). Concretely, the rejected waste streams were collected from (1) a light packaging waste sorting plant, (2) the paper recycling industry, and (3) a waste treatment plant of electrical and electronic equipment (WEEE). The influence of pre-treatments (mechanical separation operations) and temperature on the yield and quality of the liquid fraction were evaluated. In order to study the pre-treatment effect, the samples were pyrolyzed at 460 °C for 1 h. As pre-treatments concentrate on the suitable fraction for pyrolysis and reduce the undesirable materials (metals, PVC, PET, inorganics, cellulosic materials), they improve the yield to liquid products and considerably reduce the halogen content. The sample with the highest polyolefin content achieved the highest liquid yield (70.6 wt.% at 460 °C) and the lowest chlorine content (160 ppm) among the investigated samples and, therefore, was the most suitable liquid to use as refinery feedstock. The effect of temperature on the pyrolysis of this sample was studied in the range of 430–490 °C. As the temperature increased the liquid yield increased and solid yield decreased, indicating that the conversion was maximized. At 490 °C, the pyrolysis oil with the highest calorific value (44.3 MJ kg−1) and paraffinic content (65% area), the lowest chlorine content (128 ppm) and more than 50 wt.% of diesel was obtained. [ABSTRACT FROM AUTHOR]

• Promising results have been obtained in the slow pyrolysis of recycled HDPE. • Oil produced at 430 °C / 15 min is appropriate to be co-fed to FCC unit with VGO. • Oil obtained at 430°C / 37.5–60 min and at 460°C / 15 min can be treated with LCO. The slow pyrolysis of recycled high-density polyethylene (HDPE) has been investigated in a batch autoclave reactor at 430–490 °C and reaction times of 15–60 min, with the aim of obtaining the maximum yield of plastic oil (PO) with an adequate composition for its subsequent valorization in refinery. Specifically, PO yields up to 85–90 wt% have been achieved operating at 430 °C and 15–37.5 min, noting that the obtained yields strongly depend on temperature and, to a lesser extent, on reaction time. Simulated distillation and gas chromatography analyses of PO have shown its potential for its valorization in a waste refinery scheme targeting the production of alternative fuels. Thus, the PO obtained at 430 °C and 15 min is suitable to be cofed to the fluidized catalytic cracking (FCC) unit since it has a simulated distillation curve similar to that of vacuum gasoil (VGO). On the other hand, the PO obtained at 430 °C at the longest reaction time and those obtained at 460 °C are suitable to be fed together with light cycle oil (LCO) into a hydroprocessing unit. The composition of naphtha and middle distillates of PO reveals that these fractions are appropriate for their blending with commercial diesel and gasoline pools after a mild hydrotreating to reduce their olefin content. [ABSTRACT FROM AUTHOR]