Corrosion Behavior of Carbon Steel in Piperazine Solutions for Post-Combustion CO2 Capture

Abstract

The corrosion behavior of A106 carbon steel in 30 wt.% piperazine (PZ, a cycling amine) solutions was investigated by potentiodynamic polarization, EIS, LPR, SEM/EDS, and XRD. For comparison, the corrosion was also conducted in the benchmark solvent of monoethanolamine (MEA) solution. Similar to MEA, initial corrosion testing results in PZ solvent showed that the corrosion rate increases with increases either in CO2 loading from 0.23 to 0.43 mol CO2/mol alkalinity (C/N) or in temperature from 20 to 80 oC. Short term corrosion investigations showed an approximately two orders of magnitude lower corrosion rate for A106 in 0.43 C/N CO2 loaded 30 wt.% PZ at 80 oC than in the same conditions but with 30 wt.% MEA. The difference was due to the ability to form a dense and protective FeCO3 layer on the metal surface in PZ as opposed to in MEA solutions. Possible mechanisms are discussed.