# Management of Plastic Wastes through Recent Advanced Pyrolysis Processes
## 3 Recent Advances in Fuel Production from Plastic Pyrolysis
Bentonite was used as the natural mineral catalyst while HZSM-5 zeolite was selected for comparison of performance. The feedstock consisted of LDPE, PS, HDPE, and PP. The plastic mixture was prepared to ratios determined from non-recycled plastic (NRP) data from Malaysia, the US, the UK, and globally. The pyrolysis was conducted in a fixed bed reactor at a temperature between 400 \({}^{\circ}\)C and 500 \({}^{\circ}\)C. The pyrolysis process was repeated twice for each plastic mixture with and without the catalyst. Thermal pyrolysis of the plastic mixture without a catalyst for Malaysia, the UK, the US, and globally was carried out at 500 \({}^{\circ}\)C. The highest liquid oil yield of 49.94% was obtained for the global composition. The effect of zeolite and bentonite on the oil yield was carried out using the plastic composition of Malaysia. When the zeolite catalyst was used, it was observed that the highest liquid yield of 55.99% was obtained at a temperature of 450 \({}^{\circ}\)C and using 1 g of HZSM-5. However, when the bentonite catalyst was used, a higher liquid yield of 60.06% was obtained using 1 g of catalyst at 500 \({}^{\circ}\)C. Based on the results, bentonite was found to be a better catalyst for producing a high liquid yield and the least tar residue. The optimal catalytic process conditions were then applied to the UK, US, and global plastic-waste composition. The highest liquid yield of 63.01% was obtained when the global plastic composition was used. Moreover, analyzing the liquid oil, aromatic compounds were higher in oils produced by both catalysts. Also, oil produced using bentonite had higher yields, produced more alkanes and alkenes, and had better physical properties, than oil produced using zeolite. This study showed the potential of pyrolysis to convert mixed plastic waste to an alternative sustainable fuel. **Pyrolysis Effect of Type of Catalyst:** Also, another study [42] investigated the effect of different catalysts on the pyrolysis of polyethylene film waste to produce an alternative fuel. Four different catalysts were utilized in this study; they were Zeolite Ammonium, Zeolite HUSY, Zeolite HY, and Beta (HBEA), and the pyrolysis was conducted in a fixed-bed batch reactor at an operating temperature of 500 \({}^{\circ}\)C. The obtained plastic liquid yield was 37% for zeolite HY, 39% for zeolite HUSY, and 43% for Beta HBEA. All three oils had a good calorific HHV in the range of 45.8 to 48.0 MJ/kg, while the oil obtained using Beta HBEA had the lowest viscosity of 89.0 cSt (centistokes). Also, when the oils were further analyzed, they were found to be similar to conventional fuels. The pyrolysis oil produced in this study consisted mainly of naphthene and aromatic compounds. It was found that the catalytic pyrolysis of PE reduced the high paraffin content and increased the naphthene and aromatic contents that were found in oils produced from the thermal pyrolysis of PE waste by 13% to 68% [43; 44]. Moreover, analyzing the oil using TGA, FT-IR, and GC-MS, the carbon-number compounds found in the oil changed to C7-C32, which present kerosene, heavy naphtha, and diesel fractions in different ratios based on the type of catalyst used. For instance, HBEA produced the largest amount of transportation fuels because of its high ability for cracking heavy hydrocarbons. This study showed the important role of catalysts in converting plastic waste, namely PE, to produce valuable oils with potential industrial applications.