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Effect of the Presence of Hydrogen Sulfide on the Formation of Light Gases, Soot, and PAH during the Pyrolysis of Ethylene

Abstract:

The formation of light gases, soot, and 16 polycyclic aromatic hydrocarbons (EPA-PAH), classified as priority pollutants by the United States Environmental Protection Agency (USEPA), has been studied during the pyrolysis of mixtures of ethylene with hydrogen sulfide (H<inf>2</inf>S) in a tubular flow reactor setup. The study was made using a constant concentration of ethylene and different inlet concentrations of H<inf>2</inf>S, in a temperature range from 1075 to 1475 K. The light gases produced were quantified by a chromatographic method. The soot amount formed was also quantified at the outlet of the reactor. The speciation of the individual EPA-PAH compounds was made by a combination of Soxhlet extraction, extract concentration by a rotary evaporator, and gas chromatography coupled to mass spectrometry. The present study shows that, under pyrolysis conditions, there is an effective interaction between H<inf>2</inf>S and hydrocarbons, forming significant amounts of CS<inf>2</inf> and bonding sulfur to soot. The presence of H<inf>2</inf>S in the pyrolysis of ethylene contributes to slightly decrease the formation of soot and EPA-PAH, which indicates a positive effect of the sulfur compound under pyrolysis conditions.