Validation of a Liquid Chromatography Tandem Mass Spectrometry Method for Targeted Degradation Compounds of Ethanolamine Used in CO 2 Capture: Application to Real Samples

Validation of a Liquid Chromatography Tandem Mass Spectrometry Method for Targeted Degradation Compounds of Ethanolamine Used in CO2 Capture: Application to Real Samples — In the field of greenhouse gas emission, a promising approach consists in CO2 storage and capture. However most of the processes are based on amine solutions which are likely to Oil & Gas Science and Technology – Rev. IFP Energies nouvelles, Vol. 69 (2014), No. 5, pp. 821-832 Copyright 2014, IFP Energies nouvelles DOI: 10.2516/ogst/2014021 degrade and produce potentially harmful compounds. So there is a need for analytical methods to identify and quantify these products. Monoethanolamine was used as a model compound for the amines used for CO2 capture. A liquid chromatography tandem mass spectrometry method was developed and validated for the quantification of six products of degradation of monoethanolamine (Glycine, N-(2-hydroxyethyl) glycine, N-glycylglycine, bicine, N,N0-bis-(2-hydroxyethyl) urea (BHE Urea), and diethanolamine) that were systematically detected with a LC-MS Scan method in real samples from CO2 capture and storage processes. The main difficulty of this study and its originality ly in the strategy developed to overcome the complexity of the matrix which is a mix of water and amine (70/30): the combined use of deuterated internal standards and a recent chemiometric approach to validate the method, i.e. the accuracy profile. For five compounds, it was possible to validate the method with acceptance limits of 20%. This method was then successfully applied to real samples from pilot plant and lab-scale experiments. HIGHLIGHTS – An analytical method based on LC/MS-MS was developed and validated using the accuracy profile; – 6 priority compounds issued from MEA degradation were quantified in pilot plant and lab-scale experiments samples; – Use of deuterated internal standards was found to be relevant to overcome the complexity of the matrix. INTRODUCTION CO2 capture and storage is one of the promising technologies to reduce greenhouse gas emissions. To be used, this technology needs economic but also environmental acceptance. In some processes, amines are known to react with flue gas components (O2, CO2, NOx, SOx, etc.) to form degradation products, and some of them could be potentially dangerous to humans or environment according to their toxicity and their concentration. These products could be discharged to the atmosphere essentially with treated flue gas. Such amine degradation causes also amine loss, therefore additional costs, and can lead to corrosion [1], solid deposit [2] and foaming. Therefore it is necessary to list all the degradation products of amines used in CO2 capture, to understand their formation and to study their toxicity. Alkanolamines are the most studied molecules. The benchmark molecule is MonoEthanolAmine (MEA) [3-8], but some other amines were studied: mainly DiEthanolAmine (DEA) [9-11], MethylDiEthanolAmine (MDEA) [12-14], PiperaZine (PZ) [15] and 2-Amino-2-MethylPropan-1-ol (AMP) [16]. Some alkyl amines and polyamines were studied [17-20]. The identification of amine degradation products and their mechanisms of formation were recently reviewed [21]. Amine degradation in post-combustion CO2 capture is a main problem because of its consequences on process units and the potential impact of degradation products on environment. Therefore, amine degradation study is a key point for CO2 capture acceptance. This is the reason why methods are required to detect, identify and quantify degradation products. 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. A recent article [22] showed the presence of ten new degradation products (pyrazine and nine alkyl derivatives) using an analytical method based on Head Space Solid Phase Micro Extraction (HS-SPME) and Gaz Chromatograhy Mass Spectrometry (GC–MS). To go further into the analysis of degradation products, the study focused on six other compounds (Glycine, N-(2-hydroxyethyl)glycine, N-glycylglycine, bicine, N,N0-bis-(2-hydroxyethyl) urea, and diethanolamine) which were systematically detected with a LCMS Scan method in real samples from IFP Energies nouvelles (IFPEN) pilot plant and lab-scale experiments. As those six compounds were considered as priority compounds by people in charge of the CO2 capture process (IFPEN) and as most of them were not compatible with GC-MS analysis, a liquid chromatography approach had to be developed and validated to determine if they can be quantified in such a complex matrix. The use of a porous graphitic carbon column was found to be relevant in this study according to the complexity of the matrix and the high range of polarity of compounds. Validation was carried out using the total error concept and the accuracy profile which will be detailed in Section 1.4. 822 Oil & Gas Science and Technology – Rev. IFP Energies nouvelles, Vol. 69 (2014), No. 5