Effect of pretreatment synergistics on Shenfu low-rank coal pyrolysis in molten metal

The two key factors that significantly impact coal pyrolysis are its structural composition and the medium in which it is carried out. In this study, effects of acid pretreatment (AP), hydrothermal pretreatment (HTP), and acid-hydrothermal synergistic pretreatment (AP-HTP) on Shenfu Low-rank coal (SF) structure were investigated. In molten metals (MM), the distribution and composition of coal pyrolysis products were investigated to evaluate the impact of pretreatment synergistics. The results showed that changing the structure of the coal had a significant effect on the pyrolysis behavior. The molten metal stimulated the pyrolytic conversion of the coal. Pyrolysis in molten metal with AP-HTP synergistic pretreatment coal (SF-AH/MM) increased the tar yield and reduced the water yield. The tar of SF-AH/MM increased aromatic and phenolic compounds, while decreased the aliphatic and oxygen compounds. The H2 increased by 19.48 % and carbon oxides decreased for the gas of SFAH/MM. Moreover, the char of SF-AH/MM enriched the aromatic structure and the content of the perfect graphite crystal structure, while reduced the degree of graphite lattice defects. The pretreatment synergistics affected the structure of coal and the molten metals enhanced the pyrolysis process, the distribution of products was optimized. Pyrolysis of synergistic pretreatment coal in molten metals is promising to enhance the tar yield, the H2 yield and improved the quality of the char.