Effect of Na on the condensation reaction of naphthalene molecules during coal pyrolysis

Abstract

The soot produced in the process of coal pyrolysis seriously affect the atmosphere environment and health of human beings. This study used naphthalene-the most abundant precursor species in coal tar-was used as a raw material to conduct pyrolysis experiments in a self-designed drop tube furnace, combined with density functional theory, to explore the influence mechanism of Na in the formation of coal-derived soot. The microstructure and functional group information of soot derived from the pyrolysis of naphthalene are obtained through transmission electron microscopy, infrared spectroscopy, Raman spectroscopy and XPS analysis. The experimental result shows that Na can inhibit the aggregation of polycyclic aromatic hydrocarbons, resulting in a shorter average length of graphite-like crystallites in the soot particles, and promoting the oxidation of the soot surface. The simulation result shows that Na inhibits the polymerization of aromatic rings. These experiments and simulation results show that the ions formed by gaseous Na form a Na+-π structure with naphthalene, which increases the energy barrier of the reaction between naphthalene molecules and naphthalene radicals and inhibits the polymerization of aromatic rings.