Composition Analysis of CO₂−NH₃−H₂O System Based on Raman Spectra

Abstract

We used Raman spectroscopy to systematically and comprehensively measure the concentrations of the main ion components (NH2COO−, HCO3 −, and CO3 2−) in the CO2−NH3−H2O system for an initial total ammonia concentration [A] = 0.69, 0.88, 1.09, 1.34, 1.60, and 2.10 mol·L−1 and CO2 loading [C]/[A] = 0.18, 0.35, 0.43, 0.50, and 0.67, respectively. The experimental data were processed using two existing theoretical methods, and the analysis on results allowed us to propose a number of improvements based on these theoretical methods. Experimental results show that upon increasing [C]/[A], the ratios of [NH2COO−] and [CO3 2−] to total carbon decrease linearly, whereas the ratio of [HCO3 −] to total carbon increases linearly. The reaction process can be divided into three steps. Considering the impacts of experiment errors, [A] has little effect on the relative composition of the system in the range we studied. Results calculated with a revised theoretical method are in better agreement with the experimental data.

Post-combustion CO2 capture by aqueous ammonia: A state-of-the-art review

“…As the concentration of CO 2 increases, carbamic acid gradually converts into carbonic acid through the so-called decomposition-recombination pathway. (Zhao et al, 2011). The similar conclusion was theoretically supported by an extended UNIQUAC electrolyte model developed by Thomsen and Rasmussen in a temperature range from 0 to 110 • C and pressure up to 100 bars (Darde et al, 2009(Darde et al, , 2011.…”

Effect of Carbonate Ion Species on Direct Ammonia Fuel Cell Employing Anion Exchange Membrane

“…The platinum wire and reversible hydrogen electrode (RHE) were used as a counter electrode and a reference electrode, respectively, in the conventional three-electrode cell. [15][16][17][18] and following relationships were used for the chemical equilibrium calculation; mass balance of carbon species (Eq. 6) and nitrogen species (Eq.…”

“…is the band intensity of ClO , was determined by the procedure described in the previous report, 18 and it was derived from the band intensity of H 2 NCO were 0.27, 0.089, and 0.088 L mol −1 , respectively. The concentrations of ion species in the KOH-K 2 CO 3 -KHCO 3 -NH 3 electrolyte solutions were determined by the following procedure.…”

Chemical speciation of CO2 absorption in aqueous monoethanolamine investigated by in situ Raman spectroscopy

“…To eliminate these factors, a ratio of species peak is normalized against another component. For CO 2 absorption in solution with amine functional group, sodium perchlorate (NaClO 4 ) was commonly used as internal intensity reference (Kim et al, 2008;Wen and Brooker, 1995;Zhao et al, 2011). NaClO 4 (AR grade, Merck Sdn Bhd) was added to all solutions to concentration of 0.517 mol/kg.…”

“…It is relatively fast, suitable for measurements in aqueous system because of the weak Raman scattering of water molecules and application of fiber optic probes allows easy handling for in situ reaction monitoring (Pelletier, 2003). Raman was used to characterize and measure species distribution in CO 2 loaded ammonia solution (Kim et al, 2008;Wen and Brooker, 1995;Zhao et al, 2011). Several researchers published speciation data in CO 2 loaded aqueous amine based solvent system.…”