## 3 Results and Discussion
### Impact of Moisture Content on Tar Formation
Phenol has the highest decreasing value of tar concentration, as the moisture content increased. The standard deviation range corresponds to a 95% confidence interval (CI). For example, phenol compound decreased in tar concentration from \(14.73\pm 1.69\) g/Nm\({}^{3}\) in 2 wt. % moisture content to \(10.97\pm 0.76\) g/Nm\({}^{3}\) in 6 wt. %, including in heterocyclic aromatic compounds. Besides, the minority of the tar formation is toluene and indene, which had declining concentration in the rising of moisture \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Stoichiometry** &
\begin{tabular}{c} **Standard Heat of** \\ **Reaction (k/mol)** \\ \end{tabular} & **Name** & **Number** \\ \hline Biomass \(\rightarrow\) char + tar + H\({}_{2}\)O + light gas (CO + CO\({}_{2}\) + H\({}_{2}\) +CH\({}_{4}\) + C\({}_{2}\) + N\({}_{2}\) +... ) & Endothermic & Biomass de-volatilization & R1 \\ \hline \multicolumn{4}{c}{_Char combustion_} \\ C + 1/2O\({}_{2}\)\(\rightarrow\) CO & \(-\)111 & Partial combustion & R2 \\ C + O\({}_{2}\)\(\rightarrow\)CO\({}_{2}\) & \(-\)394 & Complete combustion & R3 \\ Char gasification & & & \\ C + CO\({}_{2}\)\(\rightarrow\)2 CO & +173 & Boudouard reaction & R4 \\ C + H\({}_{2}\)O \(\rightarrow\) CO +H\({}_{2}\) & +131 & Steam gasification & R5 \\ C +2H\({}_{2}\)\(\rightarrow\)CH\({}_{4}\) & \(-\)75 & Hydrogen gasification & R6 \\ \hline \multicolumn{4}{c}{_Homogeneous volatile oxidation_} \\ CO + 1/2O\({}_{2}\)\(\rightarrow\)CO\({}_{2}\) & \(-\)283 & Carbon monoxide & R7 \\ H\({}_{2}\) + 1/2O\({}_{2}\)\(\rightarrow\)H\({}_{2}\)O & \(-\)242 & Hydrogen oxidation & R8 \\ CH\({}_{4}\) + 2O\({}_{2}\)\(\rightarrow\)CO\({}_{2}\) + 2H\({}_{2}\)O & \(-\)283 & Methane oxidation & R9 \\ CO + H\({}_{2}\)O \(\rightarrow\) CO\({}_{2}\) + H\({}_{2}\) & \(-\)41 & Water gas-shift reaction & R10 \\ CO +3H\({}_{2}\)\(\rightarrow\) CH\({}_{4}\) + H\({}_{2}\)O & \(-\)206 & Methanation & R11 \\ \hline \multicolumn{4}{c}{_Tar reaction (tar assumed C\({}_{n}\)H\({}_{m}\))_} \\ C\({}_{n}\)H\({}_{m}\) + (n/2)O\({}_{2}\)\(\rightarrow\) nCO + (n/2)H\({}_{2}\) & Endothermic & \\ (200–300) & & Partial oxidation & R12 \\ C\({}_{n}\)H\({}_{m}\) + nH\({}_{2}\)O \(\rightarrow\) (n/2 + n)H\({}_{2}\) +nCO & Steam reforming & R13 \\ C\({}_{n}\)H\({}_{m}\) + nCO\({}_{2}\)\(\rightarrow\) 2 nCO + (n/2)H\({}_{2}\) & Dry reforming & R14 \\ C\({}_{n}\)H\({}_{m}\) + (2n-m)/2H\({}_{2}\)\(\rightarrow\) nCH\({}_{4}\) & Hydrogenation & R15 \\ C\({}_{n}\)H\({}_{m}\)\(\rightarrow\) (n/4)CH\({}_{4}\) + (n-m/4)C & Thermal cracking & R16 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Chemical reactions from gasification [23]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Compound** & **Chemical Formula** & **Molecular Weight(g/mol)** & **Boiling Point (\({}^{\circ}\)C)** \\ \hline Phenol & C\({}_{6}\)H\({}_{5}\)OH & 94.11 & 181.7 \\ Toluene & C\({}_{7}\)H\({}_{8}\) & 92.14 & 110.6 \\ Indene & C\({}_{9}\)H\({}_{8}\) & 116.16 & 181.6 \\ Naphthalene & C\({}_{10}\)H\({}_{8}\) & 128.17 & 218 \\ Biphenyl & C\({}_{12}\)H\({}_{10}\) & 154.21 & 255 \\ Fluorene & C\({}_{13}\)H\({}_{10}\) & 166.22 & 295 \\ Phenanthrene & C\({}_{14}\)H\({}_{10}\) & 178.23 & 336 \\ Fluoranthene & C\({}_{16}\)H\({}_{10}\) & 202,26 & 375 \\ Pyrene & C\({}_{16}\)H\({}_{10}\) & 202.25 & 404 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: The nine tar compounds in biomass. content. Toluene is a light hydrocarbon aromatic compound (1 ring) which does not cause a problem in condensability and solubility. Indene is a light polyaromatic hydrocarbon compound (2-3 rings), which condenses at low temperatures, even at very low concentrations. Toluene had a decreasing value of tar concentration from \(1.68\pm 0.28\) g/Nm\({}^{3}\) in 2 wt. % moisture content to \(0.23\pm 0.05\) g/Nm\({}^{3}\) in 6 wt. %. In indene, the value decreased from \(0.57\pm 0.16\) g/Nm\({}^{3}\) in 2 wt. % to \(0.38\pm 0.11\) g/Nm\({}^{3}\) in 6 wt. %.