## 3 Results
### Analysis of the Syngas Produced  
The gasification parameters and results obtained for the tests carried out are presented in Table 9. The results demonstrate the feasibility of this type of reactor to gasify the studied fuels. In fact, hydrogen, carbon monoxide and methane are the main gases responsible for the LHV of synthesis gas. Figure 3: Raw materials used for joint gasification in the reactor. (**a**) Olive biomass residues (pellet). (**b**) Plastic waste. (Source: self-made). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Analysis**} & \multirow{2}{*}{**Parameters**} & \multirow{2}{*}{**Units**} & \multicolumn{2}{c}{**PE lights**} & \multicolumn{2}{c}{**Olive seed**} \\  & & & **Polymeric Fuel** & **Lignocellulosic Fuel** \\ \hline \multirow{4}{*}{Proximate} & Moisture & \% & 0.2 & 9.4 \\  & Volatile Matter & \% & 78.3 & 66.5 \\  & Fixed Carbon & \% & 20.9 & 19.7 \\  & Ashes & \% & 0.6 & 4.4 \\ \hline \multirow{4}{*}{Ultimate} & Nitrogen & \% & 0.46 & 1.7 \\  & Carbon & \% & 81.89 & 53.4 \\ \cline{1-1}  & Hydrogen & \% & 12.37 & 7.5 \\ \cline{1-1}  & Sulphur & \% & 1.92 & 0.1 \\ \cline{1-1}  & Oxygen & \% & 2.76 & 32.9 \\ \hline LHV (Low Heating Value) & MJ/kg & 41.8 & 20.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Fuel analysis. (Source: self-made). After a first analysis of the results obtained, it is possible to demonstrate that the gas produced contains a greater quantity of carbon monoxide than hydrogen. This situation occurred in all experiments of the mixtures tested. A lesser percentage of methane appears in the syngas. The high percentage of Nitrogen is because co-gasification has been carried out with atmospheric air [72]. For the blank test, accomplished only with olive seeds, the results present an expected rich syngas in the first analysis. In water gas shift reaction, CO and H\({}_{2}\)O are consumed, whereas CO\({}_{2}\) and H\({}_{2}\) are synthesized. The consumption rate is higher than the formation rate for CO, especially at higher temperatures [73], because CO is consumed to form hydrogen and methane in the water-gas shift and methanation reactions:  
CO + H\({}_{2}\)O \(<\)-\(>\) CO\({}_{2}\) + H\({}_{2}\) (water-gas shift)  
2 CO + 2H\({}_{2}\) \(<\)-\(>\) CH\({}_{4}\) + CO\({}_{2}\) (Methane reforming)  
The amount of H\({}_{2}\) is higher than the other experiments with polymeric mixtures. This observation is due to the relatively high experimental temperatures during the experiments. Besides, the H\({}_{2}\) concentration increase may also be related to the promotion of tar-reforming reactions [74; 75]. During the gas chromatographic analysis, small amounts light hydrocarbons, such as C\({}_{2}\)H\({}_{4}\) and C\({}_{2}\)H\({}_{6}\), were observed. Note that, under similar experimental conditions, for the non-catalytic gasification of olive seed, higher temperatures increased the formation of hydrogen and light hydrocarbons such as methane [76]. The cracking of tars can contribute to the increase in the CH\({}_{4}\) and to the consumption of CO\({}_{2}\); however, both can be consumed through the enhancement of methane reforming, in the gasification process with the rise in temperature [77]. This behavior may be the reason for the decreasing tendency observed in the values of CO\({}_{2}\) concentration, compared with the other experiments.