# Management of Plastic Wastes through Recent Advanced Pyrolysis Processes
## 3 Recent Advances in Fuel Production from Plastic Pyrolysis
The low yield of PC was denoted by the presence of oxygen, which causes a moisture content in the product, resulting in low oil yield. However, for the pyrolysis of HDPE and LDPE, the mixture of oil and wax was difficult to separate, and hence the pyrolysis oil could not be extracted. The different pyrolysis oils of the plastic wastes had different components. The oils obtained from pyrolysis PP, LDPE, and HDPE were rich in aliphatic hydrocarbons, which are paraffin, cycloalkanes, cycloalkenes, and olefins. Plastic oil from PS consists of aromatic hydrocarbons, which are monocyclic aromatic hydrocarbons and polycyclicaromatic hydrocarbons. The main oil components from the pyrolysis of PC were phenols. Other components present in the oils were MAHs (Monocyclic Aromatic Hydrocarbons) and PAHs (Polycyclic Aromatic Hydrocarbons), which contribute to the production of aviation oil. The aviation oil hydrocarbon molecular chains are normally between C8 and C16. Despite PC, the amounts of C8-C16 hydrocarbons found in PP, HDPE, PS, and LDPE were high, and were 91.02 area%, 77.52 area%, 64.79 area%, and 59.73 area%. The low-carbon hydrocarbons in pyrolysis oils from PS were much higher than high-carbon hydrocarbons. This resulted in pyrolysis oil with low viscosity and higher heating value, and hence the pyrolysis oils from PS are very similar to aviation oils. Pyrosis oils derived from HDPE and LDPE were rich in alkanes and alkenes, which are also ideal sources for oil production because of the high conversion of alkenes and alkanes. Microwave-assisted pyrolysis of plastic waste can not only efficiently solve the environmental problem of plastic pollution but also contribute to the production of valuable products, illustrating a simple and cleaner production approach. **Pyrolysis Plasma Reactor:** A very recent study [38] investigated the viability of a novel plasma pyrolysis reactor, for converting plastic waste into hydrogen-rich fuel gas. A schematic of the experimental set-up for the plasma pyrolysis reactor can be found in Figure 5d. The plastic waste tested in the study consisted of PP, PET, LDPE, and HDPE. Also, the study evaluated the effect of feed flow rate and reactor temperature on the yield and efficiency of gas, the yield of solid residue, and the ratio of H\({}_{2}\)/CO using the response surface method. The pyrolysis process was carried out at different temperatures in the range of 700-1000 \({}^{\circ}\)C, and the feed flow rate of 2.5, 5, 9, and 10 kg/h was tested. The plasma in the reactor increases the reactivity by heating the plastic feed molecules rapidly. This rapid heating leads to fast thermal cracking of the plastic, converting it to CO, CH\({}_{4}\), H\({}_{2}\), and other lighter hydrocarbons. It was observed that the plasma pyrolysis of plastic generated combustible hydrogen-rich gas and solid residue, but no liquid products were observed, unlike conventional pyrolysis. The results of the study revealed that increasing the reaction temperature increases the gas product and reduces the solid residue yield for all the plastic samples. However, for some samples like PET, the gas yield did not vary significantly with temperature. Therefore, the optimum temperature for the samples was in the range of 700-900 \({}^{\circ}\)C. The gas yield and efficiency were also found to increase with an increase in feed flow rate. An overall mass balance showed that 79.4-90.8% of the mass of the feed has been converted to product gas, with PP having the highest % yield. The technology proposed in this study is relatively fast and produces negligible amounts of CO\({}_{2}\) and tar compared to other methods. Therefore, this technique presents a novel, fast, and clean method to convert plastic waste into syngas/hydrogen fuels. **Pyrolysis natural-zeolite catalyst:** Another recent study [39] reports the conversion of HDPE and PP from plastic packaging waste into fuel oil by a pyrolysis process assisted by a natural zeolite.