# Study of Cocoa Pod Husks Thermal Decomposition
## 3 Results and Discussion
### Analytical Pyrolysis EGA Analysis
The results obtained in the flash pyrolysis of CPH at 400 \({}^{\circ}\)C showed an intermediate behavior between the temperature ranges of the slow pyrolysis described previously. Around 70 compounds have been detected, of which CO\({}_{2}\) (mainly), acetic acid, 1-hydroxy \begin{table}
\begin{tabular}{c c c} \hline \hline
**T process (\({}^{\circ}\)C)** & **Compound** & **\% Area \({}^{\ast}\)** \\ \hline \hline \multirow{8}{*}{150–350} & CO\({}_{2}\) & 17 \\  & water & 22 \\  & acetic acid & 8.3 \\  & 2-propanane,1-hydroxy- & 3.3 \\  & 2-cyclopenten-1-one, 2-hydroxy- & 1.4 \\
150–350 & phenol,2-methoxy-4-(1-propyl)- & 1.8 \\  & phenol,2,6-di-methoxy-4-(2-propyl)- & 4.9 \\  & hexadecanoic acid & 1.6 \\  & 9-octadecenoic acid & 1.3 \\  & octadecanoic acid & 1.2 \\ \hline \multirow{8}{*}{350–500} & CO\({}_{2}\) & 9.4 \\  & water & 12 \\ \cline{1-1}  & furan, 2-methyl & 1.0 \\ \cline{1-1}  & toluene & 1.4 \\ \cline{1-1}  & phenol,2-methoxy & 1.6 \\ \hline \multirow{8}{*}{400 (flash)} & CO\({}_{2}\) & 22 \\ \cline{1-1}  & acetic acid & 6.5 \\ \cline{1-1}  & 2-propanane,1-hydroxy- & 4.3 \\ \cline{1-1}  & 2-cyclopenten-1-one + furtural & 1.1 \\ \cline{1-1}  & 2-cyclopenten-1-one, 2-hydroxy- & 1.3 \\ \cline{1-1}  & 2-methoxy-4-vinylphenol & 1.0 \\ \cline{1-1}  & phenol,2-methoxy-4-(1-propyl)- & 1.0 \\ \cline{1-1}  & phenol,2,6-di-methoxy-4-(2-propyl)- & 1.0 \\ \cline{1-1}  & hexadecanoic acid & 3.2 \\ \cline{1-1}  & 9-octadecenoic acid & 1.9 \\ \cline{1-1}  & octadecanoic acid & 1.7 \\ \hline \hline \end{tabular} \({}^{\ast}\)Area percentage calculated with respect to (total area—CO\({}_{2}\) area), except CO\({}_{2}\) which has been referred to the total area.  
\end{table} 
Table 4: Area percentage of main compounds. 2-propanone and n-hexadecanoic acid stand out from the rest. No water has been identified in this process. A high number of cyclopentanone derivatives (2-cyclopenten-1-one, 2-cyclopenten-1-one, 2-hydroxy-, 2-cyclopenten-1-one,2-methyl-, 2-cyclopenten-1-one,2-hydroxy-3-methyl-, 3,5-dimethyl-cyclopentane-1,2-dione among others) coming from cellulose pyrolysis [35] is observed, while the number of phenolic derivatives obtained is much lower than that detected in slow pyrolysis up to 500 \({}^{\circ}\)C. Among the compounds of this group, it is worth highlighting phenol,2,6-di-methoxy-4-(2-propenyl)-, phenol,2-methoxy-4-(1-propenyl)- and 2-methoxy-4-vinylphenol, with the highest area percentages. Table 4 includes the compounds obtained with an area percentage greater than 1%. Besides the area percentage of the main compounds identified (Table 4), it is also interesting to compare the area/mg sample values for these compounds in the experiments carried out, since these values are representative of the product yields obtained in each case. Figure 5 compares the area/mg sample of different compounds obtained in the 3 types of experiments. The addition of the results corresponding to 150-350 \({}^{\circ}\)C and 350-500 \({}^{\circ}\)C has been also included in the figure, in order to have a better comparison with the flash pyrolysis result. In Figure 5, it can be seen how flash pyrolysis at 400 \({}^{\circ}\)C significantly increases the yield of some compounds compared to pyrolysis at higher temperature (up to 500 \({}^{\circ}\)C when considering the sum of the 2 slow pyrolysis intervals) but lower heating rate. These compounds are organic acids and ketones, that is, compounds that come mainly from the thermal decomposition of hemicellulose and cellulose. They are compounds that in the slow pyrolysis at 350 \({}^{\circ}\)C had already been generated fairly completely and an additional pyrolysis up to 500 \({}^{\circ}\)C does not increase their yield significantly. However, an increase in heating rate does.