No abstract

No abstract

In the literature, aqueous amine absorbents are widely used for post-combustion CO2 capture. Recently, benzylamine (BZA) aqueous solutions have been identified as promising solvents for CO2 capture. In this work, the kinetics of CO2 absorption in aqueous BZA, containing a primary amino group, has been studied using a stirred cell reactor with a horizontal gas liquid interface in a reaction calorimeter. Experiments were performed over a temperature range from 303.15 K to 333.15 K and the amine concentration ranging from 5 mass % to 30 mass %. Absorption rate experiments were performed in the pseudo-first-order regime to determine the overall kinetic rate constant using a fall-in-pressure technique. Both the zwitterion and termolecular mechanisms were applied to model the kinetic data and to estimate the individual reaction rate constants from experimental overall pseudo-first-order rate constants, k OV. The experimental kinetic data are better correlated by a termolecular mechanism (AAD 14.7%) compared to a zwitterion mechanism (AAD 38.02%). The density and viscosity of pure and aqueous binary mixtures of BZA are also measured over experimental temperature and concentration ranges. Empirical models are proposed to predict pure component density and viscosity data with AAD of 0.006% and 1.16% respectively. A Redlich–Kister type equation in terms of molar fraction is fitted to experimental density data, and the viscosity data for binary mixtures are correlated with Grunberg–Nissan model with AAD of 0.02% and 5.05% respectively. The reaction activation energy (E a) calculated from the Arrhenius power law model are 25.82 and 25.98 kJ/mol for zwitterion and termolecular mechanisms respectively, which indicates a lower energy barrier (∼26 kJ/mol) for the BZA–H2O–CO2 reaction system.

No abstract

In this work, carbon dioxide solubility in N-(2-aminoethyl) ethanolamine (AEEA) activated aqueous benzylamine (BZA) solutions are studied using a stirred-cell reactor in the temperature and pressure range of 313.15-333.15 K and 0.2-219 kPa, respectively. AEEA is a linear diamine with a primary and secondary amine groups, and BZA is a primary cyclic amine. The concentration of the aqueous blends used are (20mass% BZA + 10mass% AEEA), (24mass% BZA + 6mass% AEEA), and (28mass% BZA + 2mass% AEEA).Density and viscosity of unloaded aqueous amine blends are also measured in experimental temperature and concentration ranges and correlated using Joubian-Acree mathematical model. Model-predicted density and viscosity data are in good agreement with experimental results showing 0.05% and 3.41% AAD, respectively. To correlate experimental vapor-liquid-equilibrium data, Kent-Eisenberg (KE), artificial neural network (ANN), and soft models are used. Equilibrium constants of monocarbamate formation reaction of BZA and AEEA are regressed as a function of temperature and CO 2 loading to fit the experimental data with KE model expression. KE model is also utilized to estimate the pH of CO 2 loaded aqueous amine solutions. ANN model is found to predict CO 2 solubility with better accuracy (1.56% AAD) in comparison of KE model (8.27% AAD) and soft model (15.5%). The CO 2 absorption capacity of (20mass% BZA + 10mass% AEEA) solvent (~0.8 mol CO 2 /mol amine) is higher than that of monoethanolamine (~0.5 mol CO 2 /mol amine).Heats of absorption values of (BZA + AEEA) solvents (~25 kJ/mol CO 2 ) predicted from Gibbs-Helmholtz relationship are found to be lower than that of MEA (~87 kJ/mol CO 2 ) and PZ (~66 kJ/mol CO 2 ).