# Management of Plastic Wastes through Recent Advanced Pyrolysis Processes
## 3 Recent Advances in Fuel Production from Plastic Pyrolysis
[36] used an auger reactor (shown in Figure 5b) to generate fuel from the fast pyrolysis of organic and plastic waste. This study aimed to measure and analyze the density, pH, kinematic viscosity, water content, and calorific value of plastic oil to assess the applicability of the oil as a fuel for transportation. This assessment was achieved by comparing the properties of the pyrolysis oil with those of typical engine fuel. Different types of organic waste were collected and studied; these were macadamia nutshell, beauty leaf fruit husk (BLFH), and municipal green waste. The plastic waste used in the study was HDPE. The pyrolysis was performed at varied temperatures in the range of 400 \({}^{\circ}\)C to 550 \({}^{\circ}\)C, at intervals of 25 \({}^{\circ}\)C.  
Each type of waste generated the maximum pyrolysis oil yield at different temperatures. For BLFH, the maximum yield, 42.75%, was obtained at 475 \({}^{\circ}\)C and at 500 \({}^{\circ}\)C for the macadamia nutshell (45.09%) and municipal green waste (44.72%). The pyrolysis of HDPE at 525 \({}^{\circ}\)C resulted in the highest pyrolysis oil yield (61.29%). It is interesting to note that below 425 \({}^{\circ}\)C, HDPE was converted primarily to wax, which caused the auger to stop rotating, resulting in incomplete pyrolysis. However, increasing the temperature up to 550 \({}^{\circ}\)C decreased the oil yield for all the samples, because of the secondary cracking of vapor at high temperatures. Different analytical techniques such as FT-IR, TGA, GC-MS, and elemental and physicochemical-properties analyses were used to analyze the chemical and physical properties of the pyrolysis oils. The results showed that the oils produced from BLFH, municipal green waste, and macadamia nutshell are rich in aromatic, phenolic, and oxygenated compounds, while the oil obtained from HDPE is made up of mostly aromatics and hydrocarbons. Moreover, the HDPE-derived oil had lower density and viscosity, and a lower calorific value compared to that of the other oils. Based on these results, the pyrolysis oils generated from organic wastes are not appropriate for engine application and require further refinement if used. However, they can still be utilized as a heating source for boilers and furnaces. On the other hand, the characteristics of HDPE-derived oil are very similar to that of light fuel, and hence have a potential for engine application, showing the superiority of plastic waste over organic waste to produce better alternative fuels. The oil derived from HDPE can also be used to produce various fine chemicals, while the other obtained oils can be refined and used in the biofuel industry. In the future, new catalytic methods and separation approaches could be used to selectively enhance and extract valuable components from the pyrolysis oils. **Microwave-assisted pyrolysis quartz reactor:** In another recent study [37], microwave-assisted pyrolysis (MAP) of different plastic wastes was conducted to produce cleaner aviation oil. A schematic of the MAP experimental setup can be found in Figure 5c. Five different types of plastic waste were used in this study, which are polypropylene (PP), high-density polyethylene, low-density polyethylene, polystyrene (PS), and polycarbonate (PC). The reaction system consisted of a quartz reactor filled with plastic waste and microwave absorbents. Different reaction parameters such as microwave power, microwave absorbent loads, and reactor temperatures were investigated. At a temperature of 450 \({}^{\circ}\)C and microwave power of 650 W, the plastic oil generated from polystyrene had the highest yield (98.78 wt%) at a microwave absorbent load of 60 g SiC (Silicon carbide), which is currently the highest oil yield worldwide. Fixing the microwave absorbent load of 60 g, and the microwave power at 650 W, the maximum oil yield was obtained at a temperature of 460 \({}^{\circ}\)C. The plastic oil yield at these conditions for PP, PS, and PC were 78.22 wt%, 98.78 wt%, and 39.78 wt%, respectively.