The solubility of carbon dioxide in aqueous mixtures of 2,2′-methyliminodiethanol (N-methyldiethanolamine, MDEA) and 1,4-diazacyclohexane (piperazine, PZ) was measured at low gas loadings (at stoichiometric molar ratios of carbon dioxide to (MDEA + PZ) between about 0.02 and 0.83) and consequently low partial pressures of carbon dioxide (from about (0.1 to 150) kPa) at three temperatures (313 K, 353 K, and 393 K) by headspace gas chromatography. The molality of MDEA in the aqueous mixture was varied between (2 and 8) mol·(kg of water)−1 and the molality of piperazine was varied between (1 and 4) mol·(kg of water)−1. The new experimental data supplement recently published high-pressure data for the same systems. Comparisons with prediction results from a formerly published thermodynamic model reveal that the set of model parameters from that previous publication should be revised.
The solubility of hydrogen sulfide in 2 m (about 0.146 mass fraction) aqueous solutions of 1,4-diazacyclohexane (piperazine, PIPH 2 ) was measured at low gas loadings (at stochiometric molar ratios of hydrogen sulfide to PIPH 2 between about 0.14 and 1.04) and low partial pressures of hydrogen sulfide (from about (1.3 to 98.7) kPa) at (313.5 and 392.2) K by headspace gas chromatography. The new experimental results are a supplement to previously published data in the high gas-loading region. The new experimental data are compared to prediction results from a thermodynamic model that was based only on gas solubility data in the high gas-loading area. That thermodynamic model for describing the vapor-liquid equilibrium uses Pitzer's molality-based equation for the excess Gibbs energy of the aqueous solution. The average relative deviation between the new experimental results and the predictions for the partial pressure of hydrogen sulfide amounts to 10 %.
The solubility of hydrogen sulfide in an aqueous mixture
of 2,2′-methyliminodiethanol
(N-methyldiethanolamine, [CAS 105-59-9], MDEA) and
1,4-diazacyclohexane (piperazine, [CAS 110-85-0], PIPH2) was measured over a wide range of gas-loadings (stoichiometric
molar ratios of hydrogen sulfide to (MDEA + PIPH2) between
about 0.014 and 1.67) at three temperatures (about 313 K, 353 K, and
393 K) by headspace gas chromatography as well as by a synthetic gas
solubility method. The molality of MDEA in the aqueous mixture was
about 4.5 mol·(kg water)−1 and that of PIPH2 about 1.6 mol·(kg water)−1. The headspace
gas chromatography technique was applied in the low pressure range
(partial pressure of H2S between 0.64 and 125.7 kPa, stoichiometric
molar ratio of H2S to (MDEA + PIPH2) between
about 0.014 and 0.73). The synthetic method was applied in the high
pressure range (total pressure between 0.2 and 5.5 MPa, stoichiometric
molar ratio of H2S to (MDEA + PIPH2) between
about about 0.51 and 1.67). The new experimental
results are compared to prediction results from a thermodynamic model
that was parametrized using only experimental results for the solubility
of H2S data in the aqueous solution of the single amines
in the high pressure range.
In the Hot Potassium Carbonate Process, carbon dioxide (CO 2 ) is removed from gaseous streams by chemical absorption in an aqueous solution of potassium carbonate (K 2 CO 3 ). It is common to activate the solvent by adding borates and vanadates as promoters. In the present investigation, we investigate the influence of borates and vanadates on the equilibrium solubility of CO 2 in aqueous solutions of K 2 CO 3 . The solubility of CO 2 in four activated aqueous solutions of K 2 CO 3 was determined experimentally at two temperatures that are typical for CO 2 absorption (343 K) and solvent regeneration (383 K) in the Hot Potassium Carbonate Process. The mass fraction of K 2 CO 3 in the solvent was 0.26 g/g, and the mass fractions of boron (vanadium) was varied between 0.006 g/g and 0.013 g/g (0.01 g/g and 0.02 g/g). Two experimental setups were used: A headspace gas chromatography technique was applied to determine the solubility of CO 2 at partial pressures of CO 2 between 1 kPa and 140 kPa, and the synthetic gas solubility technique was applied for total pressures between 0.4 MPa and 10 MPa. The new experimental results are compared to predictions from a physicochemical thermodynamic model for the solubility of CO 2 in aqueous solutions of K 2 CO 3 that is based on the extended Pitzer equation for describing the nonidealities of the electrolyte solution. The results reveal that both the borate and the vanadate reduce the solubility of CO 2 in such solutions. The new model provides a physicochemically sound basis for process simulation of the Hot Potassium Carbonate Process.a Potassium dichromate is ineffective when H 2 S is present in the raw gas. 52 b For example, piperidine, morpholine, imidazole.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.