Corrosion Behavior of Different Steels for Sulfuric Acid Alkylation System in Ammonium Sulfate Solution

Aiming at the problem of corrosion risk of ammonium sulfate as a by-product in the sulfuric acid alkylation process, 304H steel, 316L steel and 20 steel were used as test materials, and the corrosion behavior of the test steels immersed in 6wt%, 10wt% and 44wt% (saturated state) ammonium sulfate solution for 60 d, as well as the electrochemical behavior in saturated ammonium sulfate solution of specimens after immersion for 60 d was studid. The results show that with the increase of the mass fraction of ammonium sulfate solution, the amount of flocculent corrosion products such as Fe₃O₄ and Cr₂O₃ on the surface of 304H steel increased, the corrosion mass loss and the free-corrosion current density increased, indicating the corrosion rate increased. After soaking in saturated ammonium sulfate solution for 60 d, the surface of 20 steel had multiple corrosion pits and a large amount of corrosion products, with severe intergranular corrosion, and the free-corrosion current density was the highest, indicating that its corrosion resistance was the worst. The surface of 316L steel formed a considerable amount of corrosion products and obvious intergranular corrosion, and the free-corrosion current density was moderate. The corrosion products on the surface of 304H steel were relatively few, with the lowest free-corrosion current density and the best corrosion resistance.