Thiophenic Sulfur Transformation in a Carbon Anode during the Aluminum Electrolysis Process

Given the continued increase of sulfur (mostly formed by thiophenic 5) content of petroleum coke and the inefficient desulfurization in the carbon anode process, the sulfur content of anode is becoming increasingly difficult to control. All of the sulfur in anode will be brought into the aluminum electrolysis process directly and discharged into the atmosphere. Before trying to control the S emissions, realizing the generation and transformation mechanisms of S during aluminum electrolysis process is important. We investigated the mechanisms by organic high-temperature thermodynamic calculations and simulating two representative extreme atmosphere environments of aluminum electrolysis in the experiment. Carbonyl sulfide (COS) was predicted to be the first and major product produced by thiophenic S during electrolysis. Second, based on X-ray photoelectron spectroscopy, scanning electron microscopy, arid energy dispersive spectrometry, elemental sulfur (S-x) was generated in electrolysis. Finally, cyclic reactions of thiophenic S -> COS -> H2S -> SO2, COS, thiophenic S -> COS -> SO2, -> S-x -> COS, and thiophenic S -> COS -> S-x -> CS2 -> COS, which showed that thiophenic S transformation's existed during the electrolysis process, were deduced and summarized.