Separation and structural analysis of soot from typical entrained flow coal gasification fine slag

Abstract Soot is a flocculent carbon nanoparticle that results the imperfect combustion of fossil fuel, and numerous studies are dedicated to the reduction of soot production to alleviate the associated environmental problems. However, soot as a functional material is also widely used in energy storage and superhydrophobic materials. As a partial oxidation technology, the entrained flow coal gasification process will produce part of the soot. It is important to separate soot from the coal gasification fine slag (CGFS) and understand its structural characteristics for soot utilization. For this purpose, two industrial typical pulverized coal gasification fine slag (PCGFS) and coal-water slurry gasification fine slag (WCGFS) were selected for this study. The results showed that both fine slags were rich in soot, and the dry ash free mass fraction of soot in PCGFS and WCGFS was 6.24 % and 2.91 %, respectively, and the soot of PCGFS had a hollow carbon nanosphere morphology, while the soot of WCGFS showed a flocculent irregular morphology. The average fringe length, fringe tortuosity, and fringe spacing of the soot were 0.84 nm, 1.21, and 0.45 nm, respectively. Compared to the WCGFS, the soot particles of PCGFS have less continuity of molecular bonds within the lattice, the larger the defects within the lattice, the fewer isolated lattice carbon layers there are. This study provides important theoretical support for understanding the structural characteristics and next applications of soot in the entrained flow coal gasification fine slag.