Catalytic torrefaction of beech, oak and pine woods

In this study, the effect of potassium, which plays an important role in plant growth and as a natural catalyst in the thermochemical conversion of biomass, on the torrefaction process of oak, pine and beech woods was investigated. For this purpose, powder samples of three woods were treated with potassium carbonate at different concentrations (0.005M, 0.010M, 0.015M and 0.030M) and pellets were prepared from raw wood samples with powder samples impregnated with potassium carbonate. Torrefaction was carried out in a fixed bed system. The effect of process temperature, catalyst amount and biomass type on the solid, liquid and gas product yields obtained after torrefaction process was tried to be revealed. Torrefaction was carried out at temperatures of 250 and 300 °C for 60 minutes. To determine the properties of the solid product obtained at the end of the process and to compare it with the raw biomass; proximate analysis, elemental analysis and FTIR analysis were performed. It was determined that the torrefaction process temperature was effective on the solid product yield, while the amount of catalyst was generally not effective in the medium torrefaction process. It was observed that the catalyst had an effect on the solid product yield when compared with the raw samples in the severe torrefaction process. It was concluded that the ash amount of the solid product obtained from the torrefaction process increased with both the processing temperature and the addition of catalyst. In addition, the volatile matter content of the solid product decreased significantly with the amount of catalyst and processing temperature. When the H/C and O/C ratios of the raw and potassium carbonate impregnated wood samples were reflected on the Van Krevelen diagram, it was determined that the atomic H/C and O/C ratios of the raw wood samples were higher than the torrified samples. Van Krevelen diyagramında potasyum karbonat emdirilmiş kayın ve çam ağaçlarının şiddetli kavurma işleminden elde edilen ısıl işlem görmüş örneklerin linyit bölgesine yaklaştığı görülmüştür.