Investigations on the synergistic effects of oxygen and CaO for biotars cracking during biomass gasification

In this study, thermogravimetric analysis coupled with Fourier transform infrared (TG-FTIR) spectroscopy was primarily used to investigate the extent of biotar cracking apparent from biomass pyrolysis and partial oxidative gasification with and without the addition of CaO. TG kinetic analysis indicated that the gasification process reaction rate increased as the the oxygen and CaO content increased. The effect of oxygen in the gasification environment was more significant for biotars cracking, in comparison to CaO addition, but resulted in higher CO and CO₂ yields in the syngas. However, the presence of CaO resulted in greater catalytic conversion of tars into higher H₂/CO syngas ratios at lower temperatures. In the present study, syngas with a H₂/CO ratio of ∼1.5 can be achieved under conditions of a Ca/B ratio of 3 and an O₂ content of 5%. Therefore, it is crucial to control both the oxygen and CaO content in the biomass gasification process in order to achieve synergetic effects related to biotar cracking and, ultimately, to produce syngas of the desired compositional requirement.