# Influences of the Pretreatments of Residual Biomass on
## 4 Discussion
### Peak Quantities
[38], who experimentally found that carbonaceous gases (CO\({}_{2}\) and CO) are more easily released than H\({}_{2}\) during the preliminary torrefaction pretreatment;* With regard to CH\({}_{4}\) release (Figure 6a), a significant differentiation between WSP and pretreated wheat straw pellets emerged at 900 \({}^{\circ}\)C, with \(Y^{p}_{CH_{4}\_out}\) of WSP resulting as the highest value at that temperature;
* As to CO (Figure 6c), a poorer influence from devolatilization temperature emerged, also taking into account the distribution of the \(Y^{p}_{CO,out}\) experimental points which originated the regression lines (Figure 4);
* As far as hydrocarbons are concerned (C\({}_{3}\)H\({}_{\text{geq}}\), Figure 6e), at 700 \({}^{\circ}\)C WSP-T1W and WSP-T2W showed the highest \(Y^{p}_{C_{3}H_{80},out}\), but at higher temperatures, the behavior of all biomasses became uniform;
* When considering torrefied (WSP-T1, WSP-T2, WSP-T3) and torrefied-washed pellets (WSP-T1W, WSP-T2W, WSP-T3W) as two groups, they showed a slight behavioral difference in terms of CO\({}_{2}\) peak release (Figure 6d); for all other gas components, when individually considered, clear effects ascribable to the specific pre-treatment or the variation of torrefaction temperature could not be inferred;
* For each biomass, the H\({}_{2}\)/CO molar ratio related to peak analyses (\(Y^{p}_{H_{2},out}\)/\(Y^{p}_{CO,out}\)) was calculated as the ratio between the respective \(Y^{p}_{H_{2},out}\) and \(Y^{p}_{CO,out}\) straight lines in Figure 6b,c at a given temperature, obtaining the results summarized in Table 6; remarkably, a direct influence from torrefaction temperature emerged: the higher this parameter, the greater the H\({}_{2}\)/CO molar ratio related to peaks (with a negligible exception of the very close values of WSP-T2W and WSP-T3W at 700 \({}^{\circ}\)C), in fair agreement with evidences obtained by the analysis of integral-average quantities and the already cited literature evidence from [PERSON] et al. (2016) (Section 4.1); in addition, relative percentage variation of H\({}_{2}\)/CO ratio related to peaks were calculated with WSP values as references (\(\Delta(H_{2}/CO)^{p}\), Table 6), and WSP-T3 always exhibited the greatest variation at each temperature, with the absolutely most pronounced at 700 \({}^{\circ}\)C. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & \multicolumn{2}{c}{**700 \({}^{\circ}\)C**} & \multicolumn{2}{c}{**800 \({}^{\circ}\)C**} & \multicolumn{2}{c}{**900 \({}^{\circ}\)C**} \\ \cline{2-7}
**Biomass** & \(\mathbf{Y^{p}_{H_{2},out}}\mathbf{{}^{p}_{CO,out}}\) & \(\mathbf{\Delta(\text{H}_{2}/CO)^{p}}\) & \(\mathbf{Y^{p}_{H_{2},out}}\mathbf{{}^{p}_{CO,out}}\) & \(\mathbf{\Delta(\text{H}_{2}/CO)^{p}}\) & \(\mathbf{\chi^{p}_{H_{2},out}}\mathbf{{}^{p}_{CO,out}}\) & \(\mathbf{\Delta(\text{H}_{2}/CO)^{p}}\) & \(\mathbf{\chi^{p}_{H_{2},out}}\mathbf{{}^{p}_{CO,out}}\) & \(\mathbf{\Delta(\text{H}_{2}/CO)^{p}}\) \\  & \(\mathbf{(\text{mol}_{H_{2}}\text{mol}_{CO}^{-1})}\) & **(\%)** & \(\mathbf{(\text{mol}_{H_{2}}\text{mol}_{CO}^{-1})}\) & **(\%)** & \(\mathbf{(\text{mol}_{H_{2}}\text{mol}_{CO}^{-1})}\) & **(\%)** \\ \hline WSP & 0.28 & 0 & 0.58 & 0 & 0.92 & 0 \\ WSP-T1 & 0.37 & 32 & 0.68 & 17 & 1.00 & 9 \\ WSP-T2 & 0.39 & 41 & 0.70 & 21 & 1.01 & 10 \\ WSP-T3 & 0.43 & 57 & 0.75 & 29 & 1.06 & 15 \\ WSP-T1W & 0.33 & 21 & 0.65 & 11 & 0.95 & 4 \\ WSP-T2W & 0.40 & 46 & 0.70 & 20 & 0.97 & 5 \\ WSP-T3W & 0.40 & 45 & 0.73 & 24 & 1.05 & 14 \\ \hline \end{tabular}
\end{table} 
Table 6: Peak analyses at 700, 800, and 900 \({}^{\circ}\)C: H\({}_{2}\)/CO molar ratio related to peaks, obtained as the ratio between regression lines of \(Y^{p}_{H_{2},out}\) and \(Y^{p}_{CO,out}\) (Equation (7), \(m\) and \(q\) from Tables 3 and 4) for each biomass; relative percentage variation of H\({}_{2}\)/CO ratio related to peaks, referred to WSP values \(\Delta(H_{2}/CO)^{p}\).