Amine regeneration tests on MEA, DEA, and MMEA with respect to cabamate stability analyses

Abstract

The CO2 desorption analyses of several amines were performed to reveal the behaviour of the amine regeneration process. A typical primary amine (MEA) and two other secondary amines (MMEA and DEA) were selected, in preparation for amine solutions under different concentrations, from 1–7 mol/L. The regeneration curves were generated and plotted to describe the process. It was discovered that the specific CO2 loadings (mol/mol) that distinguish the amine regeneration curves into different regions were the same for the specific amine, despite different concentrations. These points were defined as “turning points” on regeneration curves. The turning points of MEA, MMEA, and DEA are located at CO2 loadings of 0.40 mol/mol, 0.38 mol/mol, and 0.28 mol/mol, respectively. The carbamate stabilities of the three amines were compared with each other based on the slope of regeneration curves at slow region. The amine regeneration tests compared the relative heat duty at the first 2 h: MMEA > MEA > > DEA, which is the same order as carbamate stability.

CO2 desorption tests of blended monoethanolamine–diethanolamine solutions to discover novel energy efficient solvents

“…For solvent improvement studies, CO 2 desorption tests were studied on both single and blended amines solutions . Galindo et al and Shi et al studied regeneration of primary amine MEA and secondary amines (diethanolamine and MMEA) under different aspects. Other researchers studied tertiary amine (methyldiethanolamine [MDEA], triethanolamine, and diethyl ethanolamine [DEEA]) and 2‐amino‐2‐methyl‐1‐propanol (AMP) as well .…”

“…Blending minor DEA into MEA cannot increase cyclic capacity . On the other hand, we generated a new method of solvent improvement: to blend minor MEA (<40%) into DEA as mixture, to compare heat duties with 5 M DEA as reference, which contributes approximately 55% heat duty of 5 M MEA . These blended DEA‐MEA solutions were good candidates for energy efficient solvent development.…”

“…Tertiary amines were not studied here. The experimental procedures were similar to peer researchers, by heating of preloaded rich solvents under a recirculation process. The CO 2 productions and heat duties were calculated first and then plotted to compare with 5 mol/L MEA and DEA solutions as references.…”

“…Later on, the CO 2 desorption curves were studied to investigate the focus of blended solvents: critical point (specific CO 2 loading that distinguish fast/slow stages) . We already studied the regeneration curves of MEA and DEA solutions, the critical points are 0.40 mol/mol for MEA and 0.28 mol/mol for DEA solutions under 1–7 mol/L concentrations .…”

“…Later on, the CO 2 desorption curves were studied to investigate the focus of blended solvents: critical point (specific CO 2 loading that distinguish fast/slow stages) . We already studied the regeneration curves of MEA and DEA solutions, the critical points are 0.40 mol/mol for MEA and 0.28 mol/mol for DEA solutions under 1–7 mol/L concentrations . From the ion speciation plots of MEA‐CO 2 ‐H 2 O and DEA‐CO 2 ‐H 2 O systems, these specific loadings are the exact loadings where bicarbonate (HCO 3 − ) started to be detectable .…”