Effects of different atmospheres on sulfur transformation during K₂CO₃ catalytic pressurized pyrolysis of coal

The effects of K₂CO₃ and atmospheres on sulfur distribution and forms during pressurized coal pyrolysis were investigated in a lab-scale reactor. The results show that K₂CO₃ increases the sulfur remained in char by capturing H₂S during coal pyrolysis. The surface of the coal char is activated in the presence of K₂CO₃, and then the nascent sulfur releasing from the pyrite is captured by the organic matrix in coal to form new organic sulfur. Hydrogen shows positive effects on removal of pyrite and organic sulfur, and the released H₂S is partly fixed in char in the form of K₂S when K₂CO₃ was added. The decomposition of pyrite is enhanced in H₂O atmosphere. Meanwhile, K₂S in char can not exist due to effect of water vapour, so the sulfur remained in char is notably reduced. The catalytic property of K₂CO₃ on char gasification is not changed after pyrolysis in two-stage catalytic coal gasifier.