## 3 Results and Discussions
### Physical Characterization of Pyrolytic Oil  
In previous work by [PERSON] et al. [34], a study was carried out on the liquid yields using these catalysts, obtaining a liquid yield of 37% for HY, 39% for HUSY and 43% for HBeA.  
The pH and viscosity of oil samples were determined in previous work [35]. The pH of all the samples was 6. The oil obtained with the HY catalyst had a viscosity of 137 cSt, the oil obtained with the HUSY zeolite had a viscosity of 209 cSt, and the oil obtained with the ammonium beta zeolite had a viscosity of 89 cSt at 313 K [33]. Other physical properties measured for the different oils are shown in Table 3.  
The values for carbon and hydrogen contents differ only slightly between samples. The oils obtained with the different catalysts had a carbon content between 83.4 and 84.5%, similar to that obtained without a catalyst (83.2%) and an almost hydrocarbon-carbon ratio. Similar elemental analysis was observed by [PERSON] et al. [36] for oils obtained from the pyrolysis of a mixture of PE, PP, PS, poly(ethylene terephthalate) (PET) and poly(vinyl chloride) (PVC) at 713 K for 30 min using a zeolite as a catalyst. Similar elemental analysis was also observed by [PERSON] et al. [37] in oils derived for HDPE using a pyrolysis-catalytic cracking process with a copper carbonate catalyst. The density of the four samples was 0.816 to 0.825 g/cm\({}^{3}\). Their API gravities were within 40-42\({}^{\circ}\), and the calorific values varied between 45.8 and 48.0 MJ/kg. The values of the HHV show an interesting result since they are among those of gasoline (46.1-48.2 MJ/kg) and kerosene/diesel (44.0-46.9 MJ/kg). The liquid product obtained by the HBeA catalyst is closer to the diesel range, whilst the density was within the range of kerosene (0.774-0.840 g/cm\({}^{3}\)).  
As was indicated in the materials and methods section, the API gravity is used to classify the pyrolytic oils as light, medium, heavy or extra-heavy. According to values reported in Table 3, the pyrolytic oils are categorized as light oils.  
The high values show the need for a viscosity reduction process regarding viscosity. For example, a viscosity range between 1 and 100 cSt at 293 K is the most common range for commercial fuels. It could be adequate for pyrolysis oils to facilitate its recovery, transportation and final use. However, adding the ammonium beta CP 814E catalyst promoted a decrease in viscosity. Nevertheless, it was still a very high value due to the characteristics and proportion of the catalyst used.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Catalyst** & **Without Catalyst** & **HY** & **HUSY** & **Ammonium Beta** \\  & & **CBV 600** & **CBV 720** & **CP 814E** \\ \hline C (wt\%) & 83.2 & 83.8 & 84.5 & 83.4 \\ H (wt\%) & 14.0 & 13.5 & 13.8 & 12.8 \\ N (wt\%) & 0.28 & 0.44 & 0.18 & 0.22 \\ O (wt\%) & 2.61 & 2.24 & 1.55 & 3.58 \\ H/C (molar ratio) & 2.01 & 1.93 & 1.96 & 1.84 \\ O/C (molar ratio) & 0.024 & 0.020 & 0.014 & 0.032 \\ Density (g/cm\({}^{3}\)) & 0.823 & 0.816 & 0.825 & 0.817 \\ API gravity & 40.2 & 41.8 & 39.8 & 41.6 \\ Viscosity (cSt *) & 1352 & 137 & 209 & 89 \\ HHV (MJ/kg) & 47.6 & 47.2 & 48.0 & 45.8 \\ pH * & 5.9 & 6.0 & 6.0 & 6.0 \\ \hline \end{tabular}  
* Data from [12; 34; 35].  
\end{table}
Table 3: Physical characterization of the pyrolytic oil samples using different zeolites.