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

Abstract

The alloys K90941 and N08811 were tested under conditions simulating a pyrolysis process of post-consumer plastics. Impurities in the plastic feedstock like chlorine containing materials or organic components yield HCl and H 2 S respectively during the cracking process. The reactor material must be able to withstand these harsh corrosive conditions. In lab-scale test equipment, process conditions of the reactor zone of the pyrolysis process were simulated at temperatures of 420 °C and 580 °C for 72 h. The gas atmosphere consisted of either 200 ppm or 20000 ppm H 2 S and 3.8 vol% HCl, 1.9 vol% CO 2 , 0.3 vol% CO, 2.8 vol% H 2 , bal. N 2 . After the corrosion experiments, the samples were analyzed by metallography, SEM/EDX, and XRD. Additionally, the mass loss was evaluated. Results show that the ferritic K90941 is more aggressively attacked than the austenitic N08811 and that for both materials the mass loss rises with increasing H 2 S content in the gas atmosphere and increasing temperature.

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