Modeling the Formation of Degradation Compounds during Thermal Degradation of MEA

Lucas Braakhuis,Karen Karolina Høisæter,Hanna K Knuutila

doi:10.1021/acs.iecr.1c04496

Lucas Braakhuis, Karen Karolina Høisæter + Show 1 more

Open Access

https://doi.org/10.1021/acs.iecr.1c04496

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Abstract

A kinetic model has been developed to predict thermal degradation of aqueous solutions of monoethanolamine (MEA) in carbon capture. The model focusses on both the degradation rate of the amine and the formation rates of selected degradation products as a function of time, temperature, and loading. Experimental literature data on thermal degradation of MEA were used to develop, fit, and evaluate the model. The model was found to have an average relative deviation of 17.5%, most of which was caused by uncertainty in experimental data. The degradation model was also compared to a cyclic degradation campaign. The concentration of 1-(2-hydroxyethyl)-2-imidazolidinone (HEIA), one of the more stable thermal degradation products, is well-predicted with the thermal degradation model. However, the results also indicate that oxidative and thermal degradation mechanisms interact and that this interaction influences the concentration of several thermal degradation products.

Highlights

A reduction in carbon emissions is essential in reaching climate goals
The rate coefficients are significantly lower for reactions 1 and 5, the reaction rate is in the same order of magnitude for all the reactions
The reason for this is that both reactions 1 and 5 have MEA as a reagent, which is present in much higher concentrations compared to the other compounds

Summary

■ INTRODUCTION

A reduction in carbon emissions is essential in reaching climate goals. One of the most promising processes for reducing these emissions in the short term is amine-based postcombustion carbon capture, as it is a process that can be retrofitted to current industrial installations. Several degradation models have been proposed to predict thermal degradation rates of MEA.[5,6] The role of these models is to predict solvent losses in the process and the formation of degradation products. Depending on which amine group reacts with CO2, two different isomers can be formed: N-(2-aminoethyl)N′-(2-hydroxyethyl)imidazolidinone (AEHEIA) or N-[2-[(2hydroxyethyl)amino] ethyl]imidazolidin-2-one (HEAEIA).[5,10,12] Because the isomers are similar in structure and no commercial standard was available, no consensus has been reached as to which isomer is the most likely product.[10] Another common degradation product is the urea of MEA, known as 1,3-bis(2-hydroxyethyl)urea (BHEU). AThe concentration of OZD was measured using GC−MS and possibly contains BHEU (see analytical methods)

■ METHODOLOGY

Objective

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES