Nitrogen-containing and sulfur-containing aromatic compounds in coal tar are important industrial raw materials, which can be recovered in various ways, and the SOx and NOx generated by the combustion of unrecovered compounds pollute the environment. With the progress of coking technology in recent years, the output of coal tar tends to decrease. As a valuable raw material for pharmaceuticals and functional materials, indole is urgently needed to increase its separation and refining yield.
