# Microwave Pyrolysis of Biomass: The Influence of Surface Area and Structure of a Layer
## 5 Conclusions  
The shift of the biomass sample relative to the center to the crucible wall made it possible to double the CO yield as compared with its placement in the center and to increase it by 1.5 times as compared with the distribution of the biomass over the entire bottom of the crucible. The smallest solid residue (3.4% of the initial mass) was recorded during the pyrolysis of a biomass sample displaced from the center to the crucible wall. When the biomass was distributed along the crucible wall, the proportion of the solid residue was 4.2%, and when the sample was distributed over the entire bottom of the crucible, it was 4.5%. The creation of artificial pores in the near-surface layer of biomass intensifies the diffusion of the pyrolyzing agent into the material. The processes of thermal decomposition and release of pyrolysis gas components were accelerated. Due to this approach, it was possible to increase the yield of carbon monoxide by 18% and 32% compared to \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Variable Parameter** & **Gas** & **Maximum Value** & **Minimum Value** & **K\({}_{\text{eff.}}\)** \\ \hline \multirow{6}{*}{Distribution of biomass in the crucible} & CO & 15.5\% & 8.6\% & 1.8 \\  & CO\({}_{2}\) & 7.02\% & 6.31\% & 1.11 \\  & CH\({}_{4}\) & 2.88\% & 1.8\% & 1.6 \\  & H\({}_{2}\) & 1.16\% & 0.88\% & 1.3 \\  & H\({}_{2}\)S & 67.66 ppm & 37.59 ppm & 1.7 \\  & SO\({}_{2}\) & 34.46 ppm & 16.5 ppm & 2.08 \\  & NO & 12.31 ppm & 2.77 ppm & 4.44 \\ \hline \multirow{6}{*}{Fragmented distribution of biomass} & CO & 15.5\% & 8.72\% & 1.7 \\  & CO\({}_{2}\) & 7.01\% & 5.27\% & 1.3 \\  & CH\({}_{4}\) & 3.67\% & 2.88\% & 1.2 \\  & H\({}_{2}\) & 1.47\% & 0.88\% & 1.6 \\  & H\({}_{2}\)S & 90.53 ppm & 37.59 ppm & 2.4 \\  & SO\({}_{2}\) & 28.5 ppm & 16.5 ppm & 1.7 \\  & NO & 28.63 ppm & 12.31 ppm & 2.32 \\ \hline \multirow{6}{*}{Surface structure} & CO & 16.47\% & 14.63\% & 1.12 \\  & CO\({}_{2}\) & 8.03\% & 7.01\% & 1.14 \\  & CH\({}_{4}\) & 6.45\% & 2.88\% & 2.2 \\  & H\({}_{2}\) & 1.33\% & 0.88\% & 1.5 \\  & H\({}_{2}\)S & 101.78 ppm & 37.59 ppm & 2.7 \\  & SO\({}_{2}\) & 36.81 ppm & 16.5 ppm & 2.34 \\  & NO & 12.31 ppm & 3.55 ppm & 3.46 \\ \hline \multirow{6}{*}{Average size of biomass particles} & CO & 17.38\% & 10.2\% & 1.7 \\  & CO\({}_{2}\) & 8.07\% & 6.91\% & 1.18 \\ \cline{1-1}  & CH\({}_{4}\) & 7.1\% & 2.88\% & 2.4 \\ \cline{1-1}  & H\({}_{2}\) & 1.09\% & 0.62\% & 1.75 \\ \cline{1-1}  & H\({}_{2}\)S & 106 ppm & 37.59 ppm & 2.81 \\ \cline{1-1}  & SO\({}_{2}\) & 45.05 ppm & 16.5 ppm & 2.73 \\ \cline{1-1}  & NO & 42.57 ppm & 12.31 ppm & 3.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Coefficients of microwave pyrolysis efficiency. biomass pyrolysis with artificial channels and without any artificial elements in a layer. The creation of artificial channels in a biomass layer did not lead to significant changes in the concentration of pyrolysis gas components. Microwave pyrolysis of small biomass particles (140 and 250 \(\upmu\)m) was more efficient than pyrolysis of 2000 \(\upmu\)m particles. Smaller particle size increased the concentrations of the main combustible gas components by 42%. For example, the CO yield during the pyrolysis of sawdust with a particle size of 140 \(\upmu\)m increased by 42% and 11% compared to the pyrolysis of sawdust with a particle size of 250 and 2000 \(\upmu\)m, CO\({}_{2}\) decreased by 15% and 1.5%, and CH\({}_{4}\) yield increased by 30% and 60%. During the pyrolysis of small particles, the solid residue decreases and the gas yield increases. The results obtained are of high importance for choosing the designs of reactors and platforms for loading biomass. M.K. : methodology, investigation, formal analysis; G.N. : methodology, investigation, writing-original draft; A.S.: methodology, investigation, visualization, writing-original draft; K.V. : investigation, writing-original draft, writing--review and editing; A.O.P.J. : project administration, supervision, conceptualization.