Comprehensive Evaluation of the Physical and Chemical Properties of 1-dimethylamino-2-propanol for Post Combustion CO2 Capture

Abstract

Recently the worsening global warming issue caused by emissions and accumulation of greenhouse gases in the atmosphere has become a subject of public concern. Carbon dioxide (CO2) is widely considered as the predominant contributor of greenhouse gases. The absorption of CO2 into aqueous amine solution is regarded to be one of the most promising technologies for CO2 capture due to its maturity, cost effectiveness, and capacity to handle large amounts of exhaust streams. Recently, a new tertiary amine, 1- dimethylamino-2-propanol (1DMA2P), has drawn significant attention for its good performance in capturing CO2. The objectives of the overall work are to study the physical properties and chemical properties of the potential solvent (1DMA2P) for use in the field of CO2 capture. In order to achieve this goal, the study of the physical and chemical properties of 1DMA2P was presented in terms of density, viscosity, specific heat capacity, the physical solubility, diffusivity, CO2 equilibrium solubility, ions speciation plots and reaction kinetics. The densities, viscosities, and specific heat capacity of pure 1DMA2P, unloaded 1DMA2P solution and loaded 1DMA2P solution were measured over different 1DMA2P concentration and temperature ranges. In order to correlate the obtained results, some empirical models were employed to represent the experimental physical properties of 1DMA2P. In addition, ANNs models (BPNN and RBFNN model) were developed and used to correlate the physical properties of 1DMA2P. Henry’s law constants of N2O in pure 1DMA2P as well as in 1DMA2P solutions were measured over temperature and concentration ranges. The N2O diffusivity in aqueous 1DMA2P solution was measured over concentration and temperature ranges of 1.0-3.0mol/L and 298K-333K. The present ii models and the newly developed model were used to represent those results. In order to better correlate the experimental results of N2O diffusivity and understand the process of diffusivity, a new model mechanism was developed in the present work. The equilibrium CO2 solubility in 1DMA2P solution were measured at the different conditions of concentration, temperature range, and CO2 partial pressure. All experimental values of CO2 solubility were represented by applying correlation models for K2, for the present models (Kent-Eisenberg model, Austgen model, and Li-Sheng model). A new K2 correlation model has been developed to predict CO2 solubility. In addition, the CO2 absorption heat in 1DMA2P solution was estimated by using Gibbs-Helmholtz equation. Ions (1DMA2P, 1DMA2PH+, HCO3 -, CO3 2-) speciation plots for the 1DMA2P-H2O-CO2 system were developed based on the 13C NMR technique. A new method for selecting the protonation calibration curve was also developed by considering the charge balance in the 1DMA2PH2O- CO2 system in order to give better accuracy. A comprehensive reaction kinetics model for CO2 absorption in 1DMA2P solution was developed. The reaction constant (k1DMA2P) of CO2 with 1DMA2P solution was extracted from the model. Based on the CO2 capture performance of 1DMA2P in CO2 absorption parameters, the 1DMA2P could be considered as one of the alternative solvents as DEAB and, AMP for mixing with the solvents with higher reaction rate and higher absorption heat (i.e. MEA and PZ). On the basis of the absorption parameters provided in this work, both the conventional amines and this alternative amine were analyzed for the purpose of providing the guidelines or information on how to effectively screen solvents. Key words: 1DMA2P, physical properties, Henry’s law constants, diffusivity, CO2 equilibrium solubility, ions speciation plots, comprehensive kinetics model.