A theoretical study of the reaction kinetics of amines released into the atmosphere from CO2 capture

Abstract

Amine solvents used in CO2 capture technologies result in the release of compounds such as nitrosamines and nitramines to the atmosphere. The reaction kinetics of monoethanolamine and the resulting degradation amines, methylamine and dimethylamine, are studied using transition state and collision theory. A simplified amine atmospheric chemistry scheme and three types of reactions,—with barrier, without a barrier and a photolysis reaction—are considered using geometric, energetic and thermodynamic data derived from quantum chemistry and kinetic modelling. The rate coefficients obtained are in excellent agreement with existing experimental and theoretical values. These coefficients are used within the Amine Chemistry Module of the atmospheric dispersion model ADMS 5 to solve the advection-dispersion-chemical equations. A case study on the Technology Centre Mongstad is conducted to estimate the dispersion, chemical transformation and transport pathways of these amines away from the emitting facility. Reliable estimates of the concentrations of the resulting nitrosamines and nitramines are determined and compared to safety guideline values to establish the risk these discharges may pose on the environment. This study illustrates the theoretical methodology developed and its implementation within the ADMS 5 atmospheric dispersion model, which can be used at any amine based CO2 capture facility regardless of its geographical location.