Analysis of equilibrium CO₂ solubility and thermodynamic models for aqueous 1‐(2‐hydoxyethyl)‐piperidine solution

Abstract

1-(2-Hydoxyethyl)-piperidine (1-(2HE)-PP) is a new tertiary amine with desirable properties and can be potentially used to formulate superior absorbents for CO 2 capture. The equilibrium CO 2 solubility of 1-(2HE)-PP solution is measured over temperatures from 298 to 333 K, CO 2 partial pressures from 8.1 to 101.3 kPa and initial amine concentrations from 1 to 5 M. Two thermodynamic models, namely semiempirical model and activity coefficient model are developed for the system. The activity coefficient model shows better estimation solubility with an absolute average relative deviation (AARD) of 7.6%. In the comparison between the two models, a comprehensive analysis is presented. Some suggestions are provided for the similar model development. In addition, the speciation plot of CO 2 loaded 1-(2HE)-PP solution is predicted based on the activity coefficient model. The predictive pH values agree well with experimental data with AARD of 1.0%. Finally, the potential of 1-(2-HE)PP to be an alternative amine in CO 2 capture is evaluated. K E Y W O R D S 1-(2-hydoxyethyl)-piperidine, CO 2 capture, equilibrium CO 2 solubility, speciation, thermodynamic model 1 | INTRODUCTION Excessive CO 2 emission from the combustion of fossil fuel has to be controlled due to global warming and climate change. However, fuel energy is still an important part of worldwide energy structure in the short and medium term. It requires a feasible technology to capture CO 2 from coal-fired power plants. Post-combustion capture of CO 2 (PCC) using amine solution is recognized to be one of the most viable technologies to reduce anthropogenic CO 2 emission in the visible future. 1,2

Experimental study on CO2 capture by MEA/n-butanol/H2O phase change absorbent

“…17, and then plotted linearly between In(P CO 2 ) and 1/ T. Multiply the slope of the line shown in the diagram by the gas constant 8.314 J (mol −1 K −1 ) to get the corresponding DH abs . 21 As calculated from Fig. 18a, 30 wt% MEA absorbent DH abs is 82.1 kJ mol −1 .…”

“…Multiply the slope of the line shown in the diagram by the gas constant 8.314 J (mol −1 K −1 ) to get the corresponding Δ H abs . 21…”

“…The Δ H abs is measured in two ways, either by a calorimeter or by the Gibbs Helmholtz equation. In this paper, the gas–liquid equilibrium experimental device used by Xiao 21 et al and Zhang 22 et al was used to measure the CO 2 equilibrium solubility of each amine solvent at different temperatures and different CO 2 partial pressures, and the Δ H abs was calculated by Gibbs Helmholtz equation. The Gibbs Helmholtz equation is shown in formula (8):where P CO 2 is the partial pressure of CO 2 , kPa; T is the reaction temperature, K; Δ H abs is the heat of reaction, kJ mol −1 ; R is the gas constant, 8.314 J (mol −1 K −1 ).…”

“…The DH abs is measured in two ways, either by a calorimeter or by the Gibbs Helmholtz equation. In this paper, the gas-liquid equilibrium experimental device used by Xiao 21…”

CO2 absorption intensification using three‐dimensional printed dynamic polarity packing in a bench‐scale integrated CO2 capture system

“…Speciation profiles of 5 mol/kg CAER Solvent are presented in Figure S4 to clarify the calculation for normalized free amine. The species concentration is predicted based on the activity coefficient thermodynamic model as described in the previous work 27 . The concentration of free amine decreases with CO 2 absorption to form protonated amine and carbamate products.…”