## 4 Conclusions  
Catalytic pyrolysis experiments of PE from the non-selectively collected fraction from municipal solid waste were investigated in this work. Figure 8: The effect of the micropore and mesopore area ratio in: (**a**) catalytic conversion of the oil obtained by thermal pyrolysis; (**b**) liquid fraction percentage of the oil obtained by thermal pyrolysis. Figure 7: The effect of the Br\(\Theta\)nsted/Lewis acid site ratio in: (**a**) catalytic conversion of the liquid fraction obtained by thermal pyrolysis; (**b**) bottom percentage of the liquid fraction obtained by thermal pyrolysis. Thermal pyrolysis of PE residue produces greater quantities of liquids than gases, while catalytic pyrolysis with HY, HUSY and HHEA catalysts produces a greater quantity of gases. This fact demonstrates the role of catalysts in the degradation of plastic materials, facilitating the cracking process. With the use of Y and \(\beta\) catalysts, we could reduce the temperature and reaction time compared to the thermal pyrolysis process since the use of this typology of catalysts favors the breaking of the C-C bonds of the polymeric chains, obtaining higher yields of the gaseous fractions, especially with HY and HUSY catalysts. This result may be associated with the acidic properties of HY and HUSY zeolites, which significantly promote polymer degradation. The characteristics of the liquid oil resulting from catalytic pyrolysis reveal values of density, API gravity, ash content and calorific value similar to those of fuels from fossil fuels. It is noteworthy how the use of the HY, HUSY and HHEA catalysts greatly reduces the viscosity of the liquid product when compared to the wax obtained in thermal pyrolysis; in this area, the HHEA zeolite stands out as the one that reduces the viscosity of the liquid product the most. The thermal degradation is similar for the three catalysts used. All TG curves show a great weight loss between 370 to 670 K. This weight loss occurs at a higher rate than in the product obtained from thermal pyrolysis. Thermal pyrolysis of the PE residue resulted in a liquid product composed mainly of olefins and n-paraffins. However, catalytic pyrolysis caused a decrease in the concentration of paraffinic compounds and increased the content of, in some cases, aromatic and naphthalene compounds. Additionally, the range of carbon number of compounds was changed to C\({}_{7}\)-C\({}_{32}\). Although there are numerous catalysts available for the pyrolysis process, the suitability depends on numerous variables, operating conditions, reactor typology and most importantly, the nature of the feed, which is very unfavorable in our work since the residue used comes from the fraction not selectively collected. Hence, it is quite heterogeneous both in the dirt that accompanies it and in the difference in the proportion found of LDPE and HDPE in the sample chosen in each experiment. All the catalysts used in this work produce a quality liquid product with similar properties, the most relevant differences being the viscosity and calorific value. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app12084043/s1](https://www.mdpi.com/article/10.3390/app12084043/s1)]([https://www.mdpi.com/article/10.3390/app12084043/s1](https://www.mdpi.com/article/10.3390/app12084043/s1)), Figure S1: N\({}_{2}\) adsorption-desorption isotherms at 77 K of: (a) HY CBV 600 zeolite; (b) HUSY CBV 720 zeolite; (c) ammonium beta CP 814E zeolite; Figure S2. X-ray pattern of: (a) HY CBV 600 and HUSY CBV 720 zeolite; (b) HHEA CP 814E; Figure S3: GC-MS chromatogram and simulated distillation curve of the pyrolytic oil samples from non-catalytic and in situ pyrolysis: (a) without catalyst; (b) with HY; (c) with HUSY; (d) with HBEA; Table S1: Summary of the hydrocarbon type results of GC-MS chromatogram of pyrolytic oil samples from non-catalytic and in situ pyrolysis according to designations ASTM D2425, D2786, D2789 and ASTM D3239. Contextualization and methodology, M.C. and M.A.M.-L.; Formal analysis: L.Q.