Corrosion Benefits of Piperazine As an Alternative CO₂ Capture Solvent

Abstract

The corrosion behavior of A106 carbon steel in piperazine, an advanced alternative postcombustion CO2 capture solvent to monoethanolamine, has been investigated. Electrochemical corrosion testing methods such as linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) have been used to evaluate the corrosion of A106 in 0.43 mol CO2/mol alkalinity (C/N) loaded 30 wt % piperazine at 80 °C for 150 h. In addition, immersion corrosion has been carried out up to 1050 h in a traditional corrosion cell with the same CO2 loaded solution but at 100 °C and 110 psi. Subsequently, as-corroded A106 samples were characterized by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD). The results showed that a sharp decrease in the corrosion rate occurred before reaching a steady-state corrosion process. This was due to the growth of a protective and stable layer of FeCO3. Possible mechanisms are discussed.

Recent progress and new developments in post-combustion carbon-capture technology with amine based solvents

“…The corrosion rate of this newly blended solvent has been found to be 6-7 times lower than conventional MEA and AMP/PZ blends possibly due to a limited concentration of proton (H + ) available in the reduction reaction on the cathodic side of the system. 30 wt% PZ, proposed as an alternative solvent for CO 2 capture, has also been evaluated to show its reduced corrosion rate compared to that of benchmark MEA (Zheng et al, 2014). Based on scanning electron microscopy (SEM) and Xray diffractometric (XRD) analysis, a stable iron carbonate (FeCO 3 ) that formed quickly on the entire surface of corrosion specimen (carbon steel A106) exposed to CO 2 loaded 30 wt% PZ and has been found to be a protective layer on the metal, cutting down the corrosion rate.…”

Corrosion of Carbon Steel in MDEA-Based CO2Capture Plants Under Regenerator Conditions: Effects of O2and Heat-Stable Salts

“…16 For typical CO 2 corrosion, the formation of an iron carbonate (FeCO 3 ) layer under high-temperature conditions is favorable, [17][18][19] which can drastically depress the corrosion rate. 18,20 The objective of the present study was to investigate the effects of O 2 and HSS on the corrosion behavior of carbon steel UNS K02600 (1) in CO 2 -loaded MDEA solution under regenerator conditions related to the CO 2 capture process in coal-fi red power plants, especially to monitor the variations in corrosion rate with time. Carbon steel was selected because it is widely used in regenerator shells and easily develops corrosion problems.…”

Understanding the corrosion of CO2-loaded 2-amino-2-methyl-1-propanol solutions assisted by thermodynamic modeling

“…A corrosion cell with a standard three-electrode setup was used for electrochemical testing with a saturated calomel electrode (SCE) as the reference electrode and a graphite rod as the counter electrode. The LPR method was employed to study corrosion behavior over an extended time period, and the details of this method can be found elsewhere (Zheng et al, 2015;Zheng et al, 2014a;Zheng et al, 2014b). The corrosion current density (i corr , A cm -2 ) was calculated using standard Tafel slopes of 100 mV/decade for both the anodic ( a ) and cathodic ( c ) reactions with equation 1.…”

“…To further understand the corrosion as well as formation of corrosion products, surface characterization by scanning electron microscopy (SEM) and X-ray diffraction (XRD), and solution analysis such as solution alkalinity, CO 2 loading, and pH were carried out. The details of these methods are described elsewhere (Zheng et al, 2014b;Zheng et al, 2016b). Moreover, to better identify the formed corrosion layers on the surface during different steps, the cross-section of corroded samples was prepared and characterized by FEI Helios Nanolab 660 (including focused ion beam (FIB) techniques and SEM characterization, FIB/SEM).…”

“…To understand the differences in corrosion behavior of carbon steel in AMP and MEA solutions with CO 2 loading, SEM and XRD were used to characterize the corroded samples after electrochemical testing (Figures 2 and 3). An approximately 5 m-thick and dense layer of FeCO 3 (a known protective corrosion layer), with a typical morphology of cubic clusters (Zheng et al, 2014a;Zheng et al, 2014b), was formed on the A106 surface in the AMP solution at 80°C after approximately 115 h. This is consistent with the observation of FeCO 3 on the surface of 1018 CS after 144 h in a deaerated 45 wt.% AMP solution with a continuous flow of CO 2 at 80°C (Campbell et al, 2016). In addition, the formation of a dense layer of FeCO 3 is similar to that in piperazine (a secondary amine, PZ) and methyl diethanolamine (a tertiary amine, MDEA)…”