Degradation of Amines in Liquid Matrix and Analysis : Toxicity or Innocuousness for ENvironment? – DALMATIEN

The following scientific and technical barriers have to be broken down:
1. Development of an experimental protocol representative of the industrial case. It is essential to be able to predict degradation in industrial process thanks to studies in the laboratory or on small pilot plants.
2. Development of sampling and analysis methods allowing a reliable and exhaustive identification of the degradation products and a validated quantification for a selection of target compounds. Breaking down this barrier is a central issue since all the studies are based on the analysis of gaseous or liquid samples. This project complements the many but insufficient liquid phase analysis methods. For gas analysis, the contribution is considerable since very few methods are shared in the literature.
3. Understanding of the amine degradation mechanisms of benchmark amines, monoethanolamine (MEA) and piperazine(PZ). All chemical reactions which take place in process conditions are listed to help prediction of other amines degradation. The influence of metallic materials used in industrial units is also studied.
4. Systematic study of the toxicity of the compounds formed and assessment thereof through an original QSAR approach for the missing data. The toxicological data are the ultimate results of the project. There is no such complete study today. Furthermore, an original approach is developed to calculate data that are not available in literature, so as to have a first estimation of the toxicity of the products concerned: such an approach does not exist in the literature devoted to this field of application. Besides, this study enables to highlight critical products.

Representative experimental protocols were developed in the case of MEA. They enable to obtain the same degradation products as in industrial units and are directly applicable to other amines (e.g. piperazine).
Novel analytical methods were developed for liquid phase study. They are based on chromatography coupled with mass spectrometry and may use a preliminary step of concentration of the compounds to be analysed (liquid-liquid extraction or vaporisation and concentration on solid sorbent). An innovative method was also developed to analyse traces in gas phase. Traces are adsorbed on solid sorbents which are then thermo-desorbed and analysed by GC-MS.
All these methods enabled to identify 90 MEA degradation products, 40 of which were never reported elsewhere and 30 in the case of PZ, 19 of which were novel ones. Thus novel chemical families were discovered: pyrazines, pyridines, pyrroles, oxazolines, oxazolidines, and a novel nitrosamine, the N-nitroso-2-méthyl-oxazolidine.
A mechanism was proposed to explain the formation of each degradation product. All chemical reactions which take place in process conditions were listed to help prediction of other amines degradation as PZ for example.
A catalytic effect of stainless steel on MEA oxidation was proven and it was shown that in the presence of some dissolved metallic ions some degradation products are formed to the detriment of others.
Concerning toxicity assessment, most of degradation products were classified according to Carcinogenic Mutagenic and Reprotoxic criteria. For some of them a toxicological report was established (e.g. pyrazines) and also some Acceptable Exposure Levels (AELs) for the general population (e.g. nitrosamines). Two QSAR methods were used to estimate some missing data. As a result, except for a few well-known compounds, the compounds identified in gas phase, it means potentially emitted to atmosphere, are of low concern classified.

The results of this project are very useful for CO2 capture:
• Public acceptance of CO2 capture: a list of degradation products and toxicity data are given in the case of benchmark molecules.
• Analysis methods: all methods developed in this project may be used or adapted for pilot or industrial plants monitoring.
• Tools for new CO2 capture solvents development: laboratory protocols to study amine degradation in conditions representative of industrial case, chemical reactions which may occur in function of amine structure in CO2 capture conditions and an efficient approach to assess toxicity of degradation products.

Future work would be to quantify high concern products present in gas effluent, to study their dispersion and their transformation in atmosphere and to determine their Acceptable Exposure Levels for the general population. Some in vivo studies may be done if necessary. A risk assessment for human health would be then possible. Countermeasures could be considered in the case of risk for the population.

The novel analysis methods developed in this project were described in SEP13 conference and in a paper in Oil & Gas Science and Technology. Novel degradation products and their formation mechanisms were presented in two international conferences (UTCCS2 and GHGT12), in a workshop dedicated to emissions of CO2 capture plants and were detailed in three papers (International Journal of Greenhouse Gas Control and Energy Procedia). Toxicity assessment of pyrazines discovered in this project was given in a paper in International Journal of Greenhouse Gas Control. Acceptable Exposure Levels (AELs) for the general population of nitrosamines were presented in two Eurotox conferences (2013 and 2014) and in a workshop. Seven other papers are in progress.

DALMATIEN (Degradation of Amines in Liquid Matrix and Analysis : Toxicity or Innocuousness for ENvironment?) is an industrial research project dedicated to post-combustion. The goal of this project is to list all the degradation products of amines used in CO2 capture, to understand their formation and to study their toxicity.
CO2 capture must have the lower environmental impact as possible to be used industrially. But amines used in CO2 capture process are known to react with O2, CO2, NOx and SOx to form degradation products which can be emitted in atmosphere with treated flue gas. These products aren't all known and are potentially dangerous for human living and environment.
This project is based on 4 tasks.
In the first task, laboratory conditions will be established in order to represent industrial scale conditions. Degradation will be studied in the function of O2, CO2, NOx and SOx amounts which depend on the flue gas to be treated. The influence of the type of metallic material will also be studied because it is different from an unit to another and it is known to catalyse amine degradation. MEA and piperazine will be studied because they are benchmark molecules. MEA is used in EconamineTM process (Fluor) and HiCapt+TM process (IFPEN). Piperazine is used in the process proposed by the team of G.T. Rochelle of the University of Texas and is an excellent activator for tertiary and sterically hindered amines.
In the second task, sampling and analyse methods will be created in order to identify and quantify degradation products in gas and liquid phases.
Analyses will be carried on gas and liquid effluent from a pilot plant in order to determine the impact of operation conditions (flue gas temperature, CO2 partial pressure, washing section design).
This identification is also necessary in order to understand the degradation mechanisms and the definition of reactions pathways.
A third task will be the validation of experimental procedures by considering results obtained on the lab and pilot set-ups operated by the different partners. Analyses of gas and liquid phases will be carried with the sampling and analyse method elaborated in Task 2 and compared.
Finally, a fourth task will consist in toxicology studies to be carried out on the different identified degradation products. This studies will be based on existing literature. For the compounds without any published data, a Quantitative Structure-Activity Relationship will be used to estimate a supposed toxicology. The study will take into account the impact on Human Health in order to highlight the critical compounds. This project will be used to develop countermeasures to avoid emissions or limit their impact.