## 2 Thermal Pyrolysis
### Feedstock Types and Possible Degradation Reactions
According to [35], pyrolysis of plastics can generate hydrocarbon-rich gas with a calorific value of 24-25 MJ/kg, making it attractive for energy recovery. Pyrolysis uses thermal cracking at 350-900 \({}^{\circ}\)C. Depending on the heat, pyrolysis can be done at different rates. Slow (non-isothermal), rapid (isothermal), and ultra-fast/flash pyrolysis are described. This process can be managed based on the desired outcome (gas, char, or oil). Slow pyrolysis, 10 \({}^{\circ}\)C/s heating rate, allows for the partial \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Type of Polymers for Plastics**} & \multicolumn{5}{c}{**Proximate Analysis of Plastics**} & \multirow{2}{*}{
\begin{tabular}{c} **Global** \\ **Consumption \%** \\ \end{tabular} } \\ \cline{2-2} \cline{4-5}  & **Moisture** & **FC (Fixed Carbon)** & **Volatile Matter** & **Ash** & **Consumption \%** \\  & **(wt. \%)** & **(wt. \%)** & **(wt. \%)** & **(wt. \%)** & **(wt. \%)** \\ \hline Polyethylene terephthalate (PET) & 0.46 & 7.77 & 91.75 & 0.02 & 5.5 \\ \hline Polyethylene (PE) & \multirow{2}{*}{0.10} & \multirow{2}{*}{0.04} & \multirow{2}{*}{98.87} & \multirow{2}{*}{0.99} & \multirow{2}{*}{33.5} \\ High-density polyethylene (HDPE) & & & & & \\ \hline Polyvinyl chloride (PVC) & 0.00 & 6.3 & 93.7 & 0 & 16.5 \\ \hline Polypropylene (PP) & 0.15 & 1.22 & 95.08 & 3.55 & 19.5 \\ \hline Polystyrene (PS) & 0.25 & 0.12 & 99.63 & 0 & 8.5 \\ \hline Acrylonitrile butadiene styrene (ABS) & 0.00 & 1.12 & 97.88 & 1.00 & \\ \hline Polyamide (PA) or Nylons & 0.00 & 0.69 & 99.31 & 0.00 & 3.5 \\ \hline Polybutylene terephthalate (PBT) & 0.00 & 2.88 & 97.12 & 0.00 & \\ \hline Blends, high performance and & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{13.00} \\ specialty plastics, thermosetting & & & & & \\ plastics & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Main plastic types, their parameters, and global consumption [33], with permission from Elsevier. evaporation of organic materials, and the residual product (char) is over 80% carbon. Fast pyrolysis at 100 \({}^{\circ}\)C/s targets liquid pyrolusite. It is one of the most popular pyrolytic plastic processing methods. Flash pyrolysis involves rapid heating. Compound decomposition is fast and produces gas [36]. In terms of end products, the type of material used and the construction of the reactor, the technique used, and the meaning of regulating heating rate and temperature in the chamber are important for pyrolysis of plastics. This allows for variations in pyrolysis end-product oil, gas, and liquid levels. The authors of [37] did extensive research. HDPE (high-density polyethylene) pyrolyzed at 350 \({}^{\circ}\)C in a horizontal steel reactor yielded 80% oil and 16% gas. Fixed-bed reactors for low LDPE (low density polyethylene) pyrolysis at 500 \({}^{\circ}\)C produced 95% particle-free pyrolysis oil. Batch, semi-batch, vacuum, and pressurised batch reactors operate under different conditions and use different plastic fractions. In most cases, pyrolysis of plastics is used to create pyrolytic oil, whose calorific value ranges from 21.1 to 43 MJ/kg for PVC (polyvinyl chloride) and PS (polystyrene), respectively. Changing the parameters allows for flexible product selection [37]. In some cases, the pyrolysis oil obtained had physical properties similar to gasoline and diesel. The current international situation may affect the development of the following transportation solutions.