Reactivity of the Biomass Chars Originating from Reed, Douglas Fir, and Pine

In this study, the oxidation reactivity of the chars derived from the pyrolysis of reed, pine pellets, and Douglas fir wood chips was investigated. The direct reactivity measurements were compared to the results from the indirect reactivity methods used to characterize the physical properties and chemical composition of material, such as proximate and ultimate analyses, ash chemical analysis, and specific surface area measurements. The direct reactivity measurements of the chars showed that the reed chars had lower reactivity compared to the chars derived from woods. The pine pellet char exhibited higher reactivity compared to the reed and Douglas fir wood chip char. The reed char showed the lowest reactivity because of high reaction inhibitor silicon content in the char, and in comparison to the Douglas fir wood chip char, the contents of alkali, alkali earth, and iron together were lower as well. The reed sample exhibited the highest char gasification yield on a dry and ash-free basis and the highest total residue yield after pyrolysis and gasification as well. The results of this study imply that the highly microporous structure together with a higher internal surface area and number of active sites and low Si content of the pine pellet char had a stronger impact on the gasification reactivity than the alkali/alkali earth metal contents of the Douglas fir wood chip and reed chars. The activity of alkali/alkali earth metals on gasification catalysis was inhibited by high Si content in the case of Douglas fir wood chip and reed chars, and the higher Si content and lower alkali, alkali earth, and iron contents together for the reed char are expected to be a main reason for the lower gasification reactivity compared to the Douglas fir wood chip char.