Fast pyrolysis of cotton stalk biomass using calcium oxide.

We herein investigate the various roles of calcium oxide in the pyrolysis of biomass at a variant temperatures. The evolution of pyrolysis products was examined to propose the various roles of Ca at a range of temperatures and CaO addition ratios with cotton stalk on a fixed-bed reactor. We found that upon the addition of CaO, the content of ketones produced increased, while that of acidic compounds decreased. Under similar conditions, the concentration of evolved H2 and CH4 increased, while that of CO2 decreased. Thus, variation in the CaO/biomass (Ca/B) mass ratios and pyrolysis temperatures indicated that CaO could act as a reactant, an absorbent, and a catalyst at Ca/B ratios of <0.2, >0.2, and >0.4, respectively. Moreover, at temperatures >600°C, the roles of CaO as an absorbent and a reactant were less apparent, while its role as a catalyst was enhanced.