Kinetics of the Oxidative Degradation of Aqueous Monoethanolamine in a Flue Gas Treating Unit

Abstract

An investigation of the kinetics of the oxidative degradation of aqueous monoethanolamine (MEA) was conducted in a 300-mL autoclave in the temperature range 393−443 K and MEA concentration range 2−11 kmol/m3 at 241−345 kPa O2 pressure (i.e., O2 concentration range). The results show that MEA oxidative degradation depends on both the O2 and the initial MEA concentrations, as well as the temperature, according to the intrinsic kinetic model −r MEA = 2.5 × 105e-(66 288.9/ RT )[MEA][O2]1.5. This work represents the first attempt at both obtaining intrinsic kinetic data for the oxidative degradation of MEA and formulating a kinetic model that fits the data based on the initial rate. The values obtained for the reaction orders for MEA and O2 imply that oxidative degradation of MEA is more sensitive to increases in the O2 concentration than in the MEA concentration. It also shows that, even though our experimental conditions enabled us to model the reaction as a homogeneous liquid-phase reaction, MEA oxidative degradation itself is not an elementary reaction.

Oxidative degradation of 2-ethanolamine: The effect of oxygen concentration and temperature on product formation

“…Thermal degradation has been studied by several research groups over a long period of time (Davis and Rochelle, 2009;Eide-Haugmo, 2011;Lepaumier et al, 2009a;Polderman et al, 1955) while oxidative degradation has received increased attention the last decade (Goff and Rochelle, 2004;Lepaumier et al, 2009;Rooney et al, 1998;Supap et al, 2001) as it was discovered that oxidative degradation compounds are the main products under real plant conditions (da Silva et al, 2012;Lepaumier et al, 2011a;Strazisar et al, 2003). Increased insight into the degradation mechanisms, through knowledge of stoichiometry, kinetics, and chemical pathways, may result in methods for eliminating or strongly reducing degradation.…”

“…Either the amine loss was studied working in a closed-batch reactor at elevated temperatures and oxygen pressures (Lepaumier et al, 2009;Supap et al, 2001;Wang and Jens, 2011), or in an open-batch reactor at 55 °C where the CO2-loaded amine solution would be sparged with a wet gas blend of CO2 and air (da Silva et al, 2012;Goff and Rochelle, 2004;Lepaumier et al, 2011a;Lepaumier et al, 2011b). Lately there has been increased focus on the effect of temperature swing under industrial operation and an integrated solvent degradation apparatus (ISDA) was developed where the solvent is exposed to both oxidative and thermal degradation conditions in a single system (Closmann and Rochelle, 2011).…”

“…Lately there has been increased focus on the effect of temperature swing under industrial operation and an integrated solvent degradation apparatus (ISDA) was developed where the solvent is exposed to both oxidative and thermal degradation conditions in a single system (Closmann and Rochelle, 2011). Over the years several oxidative degradation experiments were performed by researchers studying different aspects of degradation like overall degradation rate (Blachly and Ravner, 1966;Chi and Rochelle, 2002), degradation products formed (da Silva et al, 2012;Lepaumier et al, 2009;Sexton and Rochelle, 2011;Supap et al, 2006), stability of the amines (Kohl and Nielsen, 1997;Lepaumier et al, 2009;Rooney et al, 1998) and the effects of oxidation catalyst (Goff and Rochelle, 2006), CO2 loading (Bello and Idem, 2006;Chi and Rochelle, 2002;Lawal et al, 2005;Rooney et al, 1998;Supap et al, 2009;Uyanga and Idem, 2007), inhibitors (Chi and Rochelle, 2002;Goff and Rochelle, 2006), amine and oxygen concentration (Bello and Idem, 2006;Goff and Rochelle, 2004;Supap et al, 2009;Uyanga and Idem, 2007), agitation rate (Goff and Rochelle, 2004), temperature (Bello and Idem, 2006;Lawal et al, 2005;Supap et al, 2009;Supap et al, 2001). The overall degradation rate was often determined by monitoring the evolution of NH3 (Chi and Rochelle, 2002) or a combination of NH3 and peroxide (Blachly and Ravner, 1966).…”

Pilot Plant Studies for CO2Capture from Waste Incinerator Flue Gas Using MEA Based Solvent

“…Indeed, MEA has strong interaction with oxygen (Supap et al, 2001(Supap et al, , 2006Bello and Idem, 2005;Chi and Rochelle, 2002;Goff andRochelle, 2004, 2006;Sexton and Rochelle, 2009;Bedell, 2009Bedell, , 2011Bedell et al, 2011;Lepaumier et al, 2009b, c). Working closer to the absorption conditions, Sexton and Rochelle (2009) have shown that ammonia is the major by-product in the gas phase and is a good indicator of MEA oxidative degradation.…”

Oxidative degradation of amines using a closed batch system

“…Increased attention on oxidative degradation was seen after pilot plant samples showed high degree of similarity to degradation compounds found in oxidative degradation experiments (da Silva et al, 2012;Lepaumier et al, 2011a;Strazisar et al, 2003). The oxidative degradation experiments reported have been performed in variations of two setups, either in a closed-batch reactor at elevated temperature and oxygen pressure (Lepaumier et al, 2009b;Supap et al, 2001;Wang and Jens, 2011) or in an open-batch reactor at 55 °C, where the solution would be sparged with a wet gas blend of CO2 and O2/air (da Silva et al, 2012;Goff and Rochelle, 2004;Lepaumier et al, 2011b;Sexton and Rochelle, 2011). Lately, also the temperature swing The present paper describes results from oxidative degradation experiments on five amines and two amino acids in a laboratory scale closed setup at atmospheric pressure.…”