Model About the Course of Corrosion Reactions of Austenitic Steels in H2S-, HCl- and CO2-Containing Atmospheres at 680 °C

Abstract

Material selection for thermal cracking processes of anthropogenic resources is challenging. H 2 S and HCl are formed, and corrosion occurs at high temperatures. Several steels were investigated in the past. In all cases, corrosion layers were characteristically structured. On top, large chromium sulfide crystals are located, followed by a Cr 2 O 3 layer, followed by a layer enriched in chlorine and nickel. In this paper, we propose a model on the course of the corrosion reactions. By considering the water-gas shift reaction as well as the influence of H 2 S, the layer formation can be explained. As an example S31400, 240 h corrosion time at 680 °C was chosen.

Effect of Varying H2S Content on High-Temperature Corrosion of Ferritic and Austenitic Alloys in a Simulated Pyrolysis Process of Post-Consumer Plastics

“…Thereby the findings of the EDX mappings and the XRD results can be explained. This mechanism has been identified in previous studies, and a detailed explanation can be found elsewhere [17].…”

“…The test gas leaving the test chamber was neutralized in 10% KOH and 10% NaOH solution. A detailed experimental procedure and a scheme of the testing equipment can be found elsewhere [17].…”

“…At low H2S amounts and at 580°C, HCl is able to penetrate the initial oxide layer on the material and react with the base metal in order to form the corresponding metal chlorides. The Gibbs free energy of formation at 580°C is negative for chromium and iron, and positive for nickel [17]. Thus, nickel remains metallic, while HCl is consumed by the formation of CrCl2 and FeCl2.…”

Corrosion of N10276 in a H2S, HCl, and CO2 Containing Atmosphere at 480 °C and 680 °C

“…After corrosion tests with N10276 under the same conditions as in the prior experiments, the material N10276 showed a different behavior. The results of N10276 are compared with the findings of the materials S31400 and N06600, which were published in previous studies [15,16]. A detailed comparison can be found in the Discussions section in Section 4.3.…”

“…These should be specified in future works to find an appropriate reactor material. Thus, the corrosion resistance of several austenitic steels was investigated under conditions simulating the pyrolysis process of our industrial partner and some corrosion mechanisms to explain the formation of the complex corrosion layers for these materials were developed [2,3,15,16].…”