# Influences of the Pretreatments of Residual Biomass on
## 4 Discussion
### Peak Quantities  
Figures 4 and 5 summarize the results of devolatilization data analysis focused on peak quantities. In general, for all kinds of biomass, Figures 3a and 4 suggest that:  
* \(Y_{CH_{4},out}^{p}\), \(Y_{CO_{2},out}^{p}\), \(Y_{C_{3}H_{6},\ \mathrm{eq},out}^{p}\) (Equation (5)) decreased as the devolatilization temperature was increased, for all kinds of biomasses; qualitative identification analyses with the \(\mu\)GC AGILENT 490 found a high number of hydrocarbons species at 700 \({}^{\circ}\)C (\(i\)-C\({}_{4}\)H\({}_{10}\), \(n\)-C\({}_{4}\)H\({}_{10}\), C\({}_{5}\)H\({}_{12}\), i-C\({}_{5}\)H\({}_{12}\), \(n\)-C\({}_{5}\)H\({}_{12}\), \(n\)-C\({}_{5}\)H\({}_{12}\), \(C_{6}\)H\({}_{6}\), C\({}_{2}\)H\({}_{4}\)/C\({}_{2}\)H\({}_{2}\), C\({}_{2}\)H\({}_{6}\), C\({}_{3}\)H\({}_{8}\), C\({}_{3}\)H\({}_{4}\)), just some of them at 800 \({}^{\circ}\)C (\(n\)-C\({}_{4}\)H\({}_{10}\), C\({}_{6}\)H\({}_{6}\), C\({}_{2}\)H\({}_{4}\)/C\({}_{2}\)H\({}_{2}\), C\({}_{2}\)H\({}_{6}\), C\({}_{3}\)H\({}_{8}\)), while at 900 \({}^{\circ}\)C none of them was detected;
* \(Y_{H2,out}^{p}\) (Equation (5)) increased as the temperature was increased for all kinds of biomasses;
* \(Y_{CO,out}^{p}\) (Equation (5)) of pretreated pellets (Figure 4), was quite constant or slightly increased as the temperature was increased, while \(Y_{CO,out}^{p}\) of WSP (Figure 3a) decreased. These observations matched well with the discussion about integral-average parameters in Section 4.1, which highlighted that the higher the devolatilization temperature the higher the H\({}_{2}\)/CO ratio, hypothesizing an enhancement of reforming and cracking reactions of hydrocarbons due to the increasing of devolatilization temperature. Tables 3 and 4 show the coefficients \(m\) and \(q\) of regression straight lines obtained for \(Y_{i,out}^{p}\):  
* \(m\) is an index of the effects due to the variations of devolatilization temperature on the \(Y_{i,out}^{p}\) distribution in the syngas; for a generic gaseous species \(i\), a positive \(m\) means that \(Y_{i,out}^{p}\) increases as the temperature was increased (and vice versa), and the higher of the absolute value of \(m\), the more abrupt the \(Y_{i,out}^{p}\) variation due to temperature (somehow related to similar temperature effects represented by values of the Arrhenius activation energy);
* \(q\) may not have a proper physical-chemical interpretation for a given \(i\) species (anyway, it is likely interpretable analogously to the preexponential factor of Arrhenius function); in any case, being \(m\) equal, the higher the \(q\) the greater the tendency of a given biomass to release \(i\);  
Overall, for all investigated biomasses, \(m\) and \(q\) values related to \(Y_{i,out}^{p}\) (\(i\) = H\({}_{2}\), CO, CO\({}_{2}\), CH\({}_{4}\), and C\({}_{3}\)H\({}_{8,\mathrm{eq},}\), Equation (5)) did not severely differ one to another for each considered gaseous species (Tables 3 and 4); this was in agreement with the abovementioned observations about Figures 3a and 4, which generally showed quite similar trends and absolute values for \(Y_{i,out}^{p}\) of the seven investigated biomasses. Nevertheless, without prejudice to what was said in the previous sentence, the quantifications offered by \(m\) and \(q\) highlighted some minor differences between the behaviors of biomasses, associated to their devolatilization peaks; in this regard, Figure 6 compares regression lines obtained by \(m\) and \(q\) values from Tables 3 and 4 for \(Y_{i,out}^{p}\) (\(i\) = H\({}_{2}\), CO, CO\({}_{2}\), CH\({}_{4}\), and C\({}_{3}\)H\({}_{8,\mathrm{eq},}\), Equation (5)):  
* WSP appeared as less likely to release H\({}_{2}\) (Figure 6b) and more likely to release CO\({}_{2}\) (Figure 6d) than pretreated wheat straw pellets; this could be related to the results of [PERSON] et al.