# Plant Design for the Conversion of Plastic Waste into Valuable Chemicals (Alkyl Aromatics)
## 2 Materials and Methods
### Thermal Treatment or Pyrolysis in the Reactor  
In a pyrolysis reactor, the plastic feed is thermally degraded at a high temperature of more than 500 \({}^{\circ}\)C into a variety of gaseous, solid, and liquid products. The retention time decreases as the temperature is increased from 400 \({}^{\circ}\)C for 760 min to 450 \({}^{\circ}\)C for 290 min, then 500 \({}^{\circ}\)C for 68 min and 550 \({}^{\circ}\)C for 54 min. However, the technique can benefit from additional reductions in temperature and retention time. Both thermal and catalytic processes can be used to accomplish pyrolysis. The following reactors are used for pyrolysis [14]:  
* Fixed-Bed Reactor  
Since fixed-bed furnaces are simple to construct, they are the go-to choice for small-scale studies conducted in the lab. The feedstock is placed in the reactor (usually made of stainless steel) and heated outside. An electric furnace is the most popular option. To create anaerobic conditions, the engine is flooded with an inert gas (such as nitrogen or argon) before the experiment begins, and the supply line is maintained throughout the entire operation [13]. Char is typically removed after pyrolysis, but the collected gases and vapors are released during the process. A characteristic of the batch reactor is a relatively slow rate of heating. In addition, the feedstock remains stationary during the process, making large-scale, consistent heating of municipal solid waste (MSW) challenging to predict. * Fluidized Bed Reactor  
Studies of rapid pyrolysis behavior and secondary oil cracking at extended residence durations are common applications of fluidized bed reactors. The feedstock is heated rapidly and thoroughly mixed in a fluidized bed reactor. Such reactors are widely used in laboratory experiments to characterize the effect of the calcination temperature on pyrolysis behavior and products. For the pyrolysis of unwanted polymers, this type of reactor appears to be a viable choice. Since polymers have very poor high-thermal-stability viscosity, polymer combustion in a deionization reactor may yield noticeable benefits over other reactors, where heat is not transmitted as well for the shattering of polymers. * Spouted Bed Reactor  
This reactor works well with irregularly shaped, small particles, as well as materials that stick together and have a large size range. In addition, the system's gas flow is highly variable, allowing it to function with minimal gas residence times. This reactor is well-suited for flash pyrolysis because of the good movement of the materials within it, which results in rapid transfer rates of heat between phases. For larger-scale applications of biomass pyrolysis, the octagonal spouted bed reactor's suitability for continuous operation is of paramount importance. Facility locations in Germany and Japan, among others, have used rotary kiln reactors for the slow degradation of MSW. The typical treatment temperature is around 500 \({}^{\circ}\)C, and the typical residence time is around 1 h. This type of reactor is the only one that has been widely implemented as a practical industrial solution across a range of scales. However, it may sometimes call for multistage entropy (MSE) pretreatment before pyrolysis can begin. Waste needs to be sorted, then shredded to get rid of junk. Microwave-assisted Reactors  
Microwaves can be found in electromagnetic, infrared, and radio waves. Microwaves have a frequency of about 300 GHz and a wavelength of about 1 m. Both 915 MHz and 2.45 GHz are widely used in the microwave industry. Most home microwave ovens use electricity as a source of microwave energy and have a frequency of 2.45 GHz. [PERSON] and [PERSON] investigated the use of microwave pyrolysis in waste-to-energy systems [11]. They were able to define the process, but they also noted that advancements in commercial microwave equipment for this type of pyrolysis are hampered by a general lack of understanding of high-frequency applications and the technical details required for their construction.