Absorption and desorption mass transfer rates in chemically enhanced reactive systems. Part II: Reverse kinetic rate parameters
Highlights
► Forward and reverse kinetic rate parameters have been experimentally determined. ► Kinetic rate parameters were analytically and numerically derived. ► The reaction order of the forward reaction was close to unity. ► Arrhenius equations were modified to correlate reverse kinetic rate parameters. ► Kinetic rate parameters were related by a chemical equilibrium constant.
Introduction
In previous work [1], [2], it has been established that the liquid phase mass transfer coefficients for non-reactive systems and the chemical enhancement factors for reactive systems are identical for absorption and desorption mass transfer processes given identical operating conditions for the two processes. It is usually assumed and accepted that the forward and reverse kinetic rate parameters are related to each other by an overall chemical equilibrium constant at specific operating conditions; however, measurements of reverse kinetic rate parameters are very limited in the open literature, despite the industrial importance of desorption as a unit operation. Absorption and desorption mass transfer rates of in aqueous methyldiethanolamine (MDEA) solutions have previously been reported by Cadours et al. [3], Glasscock et al. [4], Jamal et al. [5], [6], Mshewa and Rochelle [7], Pacheco [8], Ramachandran et al. [9], Shi and Zhong [10], and Xu et al. [11]. In these publications, the absorption and desorption mass transfer rates are given at different experimental conditions, e.g. temperatures, liquid concentrations, partial pressures, etc., but not necessarily the reverse kinetic rate parameters. Jamal et al. [5], [6] experimentally measured the absorption and desorption mass transfer rates and numerically solved a comprehensive system of differential equations describing each individual species throughout the film in order to calculate the absorption and desorption kinetic rate parameters. The development of numerical techniques usually requires efforts, and it would be desirable to experimentally determine reverse kinetic rate parameters via simple analytical relations, as is usually carried out for determination of forward kinetic rate parameters. The purpose of the current work is to:
- 1.
determine forward and reverse kinetic rate parameters from experimental results obtained in previous work [1], [2]. The kinetic rate parameters are to be derived from simplified analytical relations based on the Higbie penetration theory and a numerically solved system of differential equations also based on the Higbie penetration theory describing each species exactly throughout the film. The results are to be compared to one another in order to investigate the possibility of using a simple analytical relation for the determination of reverse kinetic rate parameters from experimental work at different conditions;
- 2.
determine the order of the reaction of with aqueous MDEA at different temperatures and loadings in order to verify the proposed reaction mechanism;
- 3.
determine whether the experimentally determined reverse kinetic rate parameters can be correlated by Arrhenius type of equations, similar to the Arrhenius type of equations used to correlate forward kinetic rate parameters;
- 4.
determine whether the experimentally determined forward and reverse kinetic rate parameters can be related by a temperature dependent overall chemical equilibrium constant.
Section snippets
Experimental procedure
The reversible reaction of finite rate of aqueous MDEA with was applied for the determination of the forward and reverse kinetic rate parameters:with the following reaction rate equation:where c is the concentration, k is the kinetic rate parameter, the subscripts 2 and −2 refer to the respective forward and reverse reactions, and the concentration of water was set to unity. The current work treats an aqueous 2.0 M MDEA solution, and
Diffusivities of in loaded aqueous 2.0 M MDEA solutions
The experimentally determined mass transfer coefficients of , the dimensionless Re, Sc, and Sh numbers, and the diffusivities of and in loaded aqueous 2.0 M MDEA solutions are given in Table 2 at different temperatures and loadings. The densities and viscosities were taken from Weiland et al. [13]. The determined diffusivities are seen to decrease with increased loadings and increase with increased temperatures, the similar pattern seen for the mass transfer coefficients.
Analytical and numerical solutions of mass transfer theories
Conclusion
The forward and reverse kinetic rate parameters have been determined for absorption and desorption mass transfer processes in aqueous 2.0 M MDEA solutions at temperatures of 298.15, 313.15, and 333.15 K and the loading of ranging from 0 to 0.8. The derived kinetic rate parameters were based on the results of experimental work carried out in a controlled environment in a batch operated stirred tank reactor.
Forward and reverse kinetic rate parameters have been derived from simple analytical
Acknowledgments
This research has been carried out in the context of the CATO-2 program. CATO-2 is the Dutch national research program on Capture and Storage technology (CCS). The program is financially supported by the Dutch government (Ministry of Economic Affairs) and its consortium partners.
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Comparative kinetics of homogeneous reaction of CO<inf>2</inf> and unloaded/loaded amine using stopped-flow technique: A case study of MDEA solution
2020, Separation and Purification TechnologyCitation Excerpt :Modified k2 of loaded system in this work compare favorably with most literature, including those obtained from gas-liquid apparatus and rapid mixing method, which demonstrates that the modified method of kinetics of loaded MDEA and CO2 in this work is valid. The activation energy in this work, 43.9 kJ/mol, is in line with 44.9 kJ/mol from Ko and Li [22], 48.0 kJ/mol from Rangwala et al. [25], 42.4 kJ/mol from Versteeg et al. [28], 42.31 kJ/mol from Hamborg and Versteeg [19], 42.3 kJ/mol from Pani et al. [24]. k2 of unloaded system obtained from previous model, described by Eq. (7), is in a good agreement with values reported by Kierzkowska-Pawlak et al. [20], derived from a stopped-flow apparatus and estimated by kinetic model the same with this work.
Mathematical modeling of absorption accompanied by a non-elementary reversible chemical reaction
2020, Chemical Engineering Research and DesignCitation Excerpt :In order to study this phenomenon, many investigations have been conducted. Also, based on different theories, several mathematical models have been developed for diffusion and reaction of gas in the liquid to obtain the enhancement factor and mass transfer rate for gas–liquid systems (Bhat et al., 2000; Biard and Couvert, 2013; Gaspar and Fosbøl, 2015; Hamborg and Versteeg, 2012; Kierzkowska-Pawlak, 2012; Luo et al., 2015; Mathews and Panda, 2012; Oh et al., 2011; Panda and Mathews, 2014; Pashaei et al., 2016; Tizaoui and Grima, 2011; Zhu et al., 2017). The modeling of absorption with a general reaction kinetic is very complex due to the nonlinear terms in the governing differential equations.
Desorption of carbon dioxide from aqueous MDEA solution in a microchannel reactor
2017, Chemical Engineering JournalPorous media Eulerian computational fluid dynamics (CFD) model of amine absorber with structured-packing for CO<inf>2</inf> removal
2015, Chemical Engineering ScienceKinetics of the carbon monoxide reactive uptake by an imidazolium chlorocuprate(I) ionic liquid
2014, Chemical Engineering JournalCitation Excerpt :Therefore, apart from the equilibrium data, knowledge of the reaction kinetics is required for a proper design of reactive absorption units [14]. While there is a huge number of kinetic studies regarding the reactive absorption of CO2 in alkanolamines and piperazine aqueous solutions [15–18], amino-functionalized ionic liquids [19], ionic liquids containing amino acids anions [20–22] and mixtures of amines with ionic liquids [23,24], the number of kinetic studies concerning the reactive absorption of CO with copper(I) is very scarce in literature and they are limited to COSORB solutions [25–27]. In ionic liquid media, only the equilibrium data of absorption have been reported in few works: Sharma et al. [28] determined the solubility and mass transfer of CO and H2 in [bmim][PF6] in the study of the use of ionic liquids as new reaction media to perform hydroformylation of olefins [29]; in addition, pursuing the purpose of flue gas purification, we studied the reactive absorption of CO in a copper(I)-based ionic liquid at pressures up to 2 MPa and Raeissi et al. [30] obtained the solubility of CO and other gas impurities at high pressures, up to 10 MPa, in the ionic liquid [bmim][Tf2N].
Desorption Kinetics of CO<inf>2</inf> from water and aqueous Amine Solutions
2014, Energy Procedia
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Present address: Statoil Research Centre, NO-3908 Porsgrunn, Norway.