In-situ analysis of catalytic gasification reaction characteristics of coal char-CO₂ with K₂CO₃ additive

Interactions of catalyst (K₂CO₃) with Shenfu (SF)/Zunyi (ZY) char during gasification were observed by in-situ heating stage microscope. The effects of gasification temperature (750~950℃) and catalyst loading amount (2.2%, 4.4%, 6.6%) were investigated in a thermogravimetric analyzer. The results show that loading K₂CO₃ on SF/ZY stimulates development of pore structure in pyrolysis process. The in-situ heating stage experiments indicates that most of the char particles react with CO₂ in shrinking core mode below the melting point of K₂CO₃. Above this temperature, for SF char, obvious molten potassium catalyst diffusion can be observed in the later reaction stage with rapid consumption of carbon skeleton; but for ZY char, most of the molten potassium exists on the surface of coal char with slower consumption of stable carbon skeleton. Gasification reactivity of SF/ZY char increases with increasing loading amount of K₂CO₃. Catalytic efficiency of potassium catalyst on SF char initially increases and then decreases with gasification temperature, the turning point of gasification temperature is close to the melting point of K₂CO₃. This may be due to blocking of a fraction of pore structure resulted from the good fluidity of molten potassium catalyst.