Microwave-Assisted Pyrolysis of Low-Rank Coal with K2CO3, CaCl2, and FeSO4 Catalysts

Combined with the advantages of microwave pyrolysis and catalytic pyrolysis, the microwave pyrolysis experiment of low-rank coal under the synergism of catalyst was carried out. The dielectric response of coal samples and metal compound catalysts to microwave was analyzed quantitatively. The microwave pyrolysis behavior and product distribution of low-rank coal were studied. The effects of microwave heating and catalyst properties on the properties of pyrolysis products were analyzed in depth. Results show that the heating effect of dielectric loss and ionic conduction loss of metal compound catalysts could further promote the rapid temperature rise of coal samples. The catalysts could effectively improve the product distribution and properties in the process of microwave pyrolysis of low-rank coal. Compared with the control group, the output of syngas (H 2 + CO) increases by a maximum of 1.72 times, and the content of asphaltene in tar reduces by a maximum of 0.66 times. The introduction of K 2 CO 3 and CaCl 2 is conducive to the formation of a more developed pore structure and the increase of the specific surface area of semicoke. The co-action of the developed pore structure of semicoke and properties of residual catalysts could significantly improve the CO 2 gasification activity of semicoke.