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Title: High pressure supercritical carbon dioxide adsorption in coal: Adsorption model and thermodynamic characteristics

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of CO2 Utilization
Additional Journal Information:
Journal Volume: 18; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-12-12 21:33:09; Journal ID: ISSN 2212-9820
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Citation Formats

Tang, Xu, and Ripepi, Nino. High pressure supercritical carbon dioxide adsorption in coal: Adsorption model and thermodynamic characteristics. Netherlands: N. p., 2017. Web. doi:10.1016/j.jcou.2017.01.011.
Tang, Xu, & Ripepi, Nino. High pressure supercritical carbon dioxide adsorption in coal: Adsorption model and thermodynamic characteristics. Netherlands. doi:10.1016/j.jcou.2017.01.011.
Tang, Xu, and Ripepi, Nino. Wed . "High pressure supercritical carbon dioxide adsorption in coal: Adsorption model and thermodynamic characteristics". Netherlands. doi:10.1016/j.jcou.2017.01.011.
title = {High pressure supercritical carbon dioxide adsorption in coal: Adsorption model and thermodynamic characteristics},
author = {Tang, Xu and Ripepi, Nino},
abstractNote = {},
doi = {10.1016/j.jcou.2017.01.011},
journal = {Journal of CO2 Utilization},
number = C,
volume = 18,
place = {Netherlands},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}

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Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.jcou.2017.01.011

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Cited by: 2works
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  • Phase equilibria in mixtures containing carbon dioxide, water, and chloride salts have been investigated using a combination of solubility measurements and thermodynamic modeling. The solubility of water in the CO2-rich phase of ternary mixtures of CO2, H2O and NaCl or CaCl2 was determined, using near infrared spectroscopy, at 90 atm and 40 to 100 °C. These measurements fill a gap in the experimental database for CO2 water salt systems, for which phase composition data have been available only for the H2O-rich phases. A thermodynamic model for CO2 water salt systems has been constructed on the basis of the previously developedmore » Mixed-Solvent Electrolyte (MSE) framework, which is capable of modeling aqueous solutions over broad ranges of temperature and pressure, is valid to high electrolyte concentrations, treats mixed-phase systems (with both scCO2 and water present) and can predict the thermodynamic properties of dry and partially water-saturated supercritical CO2 over broad ranges of temperature and pressure. Within the MSE framework the standard-state properties are calculated from the Helgeson-Kirkham-Flowers equation of state whereas the excess Gibbs energy includes a long-range electrostatic interaction term expressed by a Pitzer-Debye-Hückel equation, a virial coefficient-type term for interactions between ions and a short-range term for interactions involving neutral molecules. The parameters of the MSE model have been evaluated using literature data for both the H2O-rich and CO2-rich phases in the CO2 - H2O binary and for the H2O-rich phase in the CO2 - H2O - NaCl / KCl / CaCl2 / MgCl2 ternary and multicompontent systems. The model accurately represents the properties of these systems at temperatures from 0°C to 300 °C and pressures up to ~4000 atm. Further, the solubilities of H2O in CO2-rich phases that are predicted by the model are in agreement with the new measurements for the CO2 - H2O - NaCl and CO2 - H2O - CaCl2 systems. Thus, the model can be used to predict the effect of various salts on the water content and water activity in CO2-rich phases on the basis of parameters determined from the properties of aqueous systems. Given the importance of water activity in CO2-rich phases for mineral reactivity, the model can be used as a foundation for predicting mineral transformations across the entire CO2/H2O composition range from aqueous solution to anhydrous scCO2. An example application using the model is presented which involves the transformation of forsterite to nesquehonite as a function of temperature and water content in the CO2-rich phase.« less
  • Adsorption isotherms of methane and carbon dioxide on two kinds of Australian coals have been measured at three temperatures up to pressures of 20 MPa. The adsorption behavior is described by three isotherm equations: extended three-parameter, Langmuir, and Toth. Among these, the Toth equation is found to be the most suitable, yielding the most realistic values of pore volume of the coals and the adsorbed phase density. Also, the surface area of coals obtained from CO{sub 2} adsorption at 273 K is found to be the meaningful parameter which captures the CO{sub 2} adsorption capacity. A maximum in the excessmore » amount adsorbed of each gas appears at a lower pressure with a decrease in temperature. For carbon dioxide, after the appearance of the maximum, an inflection point in the excess amount adsorbed is observed close to the critical density at each temperature, indicating that the decrease in the gas-phase density change with pressure influences the behavior of the excess amount adsorbed. In the context of CO{sub 2} sequestration, it is found that CO{sub 2} injection pressures of lower than 10 MPa may be desirable for the CH{sub 4} recovery process and CO{sub 2}-holding capacity.« less
  • The simplified local-density (SLD) theory was investigated regarding its ability to provide accurate representations and predictions of high-pressure supercritical adsorption isotherms encountered in coalbed methane (CBM) recovery and CO{sub 2} sequestration. Attention was focused on the ability of the SLD theory to predict mixed-gas adsorption solely on the basis of information from pure gas isotherms using a modified Peng-Robinson (PR) equation of state (EOS). An extensive set of high-pressure adsorption measurements was used in this evaluation. These measurements included pure and binary mixture adsorption measurements for several gas compositions up to 14 MPa for Calgon F-400 activated carbon and threemore » water-moistened coals. Also included were ternary measurements for the activated carbon and one coal. For the adsorption of methane, nitrogen, and CO{sub 2} on dry activated carbon, the SLD-PR can predict the component mixture adsorption within about 2.2 times the experimental uncertainty on average solely on the basis of pure-component adsorption isotherms. For the adsorption of methane, nitrogen, and CO{sub 2} on two of the three wet coals, the SLD-PR model can predict the component adsorption within the experimental uncertainties on average for all feed fractions (nominally molar compositions of 20/80, 40/60, 60/40, and 80/20) of the three binary gas mixture combinations, although predictions for some specific feed fractions are outside of their experimental uncertainties.« less
  • The dimeric cobalt complex Co{sub 2}(CO){sub 6}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}]{sub 2} (1) reacts reversibly with hydrogen to produce HCo(CO){sub 3}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}] (4). The carbonyl and the phosphine ligands of both 1 and 4 are very labile. Compound 1 reacts with CO to give Co{sub 2}(CO){sub 7}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}] (2), and compound 4 reacts with CO and P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3} (L) to give HCo(CO){sub 4} (5) and HCo(CO){sub 2}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}]{sub 2} (6), respectively. The {sup 31}P NMR studies show that, in the presence of 1, the line width of themore » {sup 31}P resonance of L is temperature dependent, and at constant temperature, its broadening is proportional to the square root of the concentration of 1. This broadening is attributed to its exchange reaction with the mononuclear cobalt radical (CO){sub 3}LCo{sup {sm_bullet}} (3), which is generated by the homolysis of 1. Compound 1 catalyzes the hydroformylation of olefins in supercritical carbon dioxide. In contrast to the unsubstituted Co{sub 2}(CO){sub 8}, the phosphine-modified catalyst system is stable under low CO pressures and the hydroformylation reactions can be carried out at low pressures. In situ monitoring of {sup 31}P and {sup 59}Co NMR spectra of the solution shows that the phosphine-containing hydrido cobalt complexes 4 and 6 are the only hydrido cobalt complexes present in detectable concentrations in 1-catalyzed hydroformylation reactions; nevertheless, the possibility that the observed activity for 1 comes primarily from the more active HCo(CO){sub 4}, present in concentrations below detectable limits, has not been rigorously excluded.« less
  • A high-pressure atomic force microscope (AFM) that enables in-situ, atomic scale measurements of topography of solid surfaces in contact with supercritical CO2 (scCO2) fluids has been developed. This apparatus overcomes the pressure limitations of the hydrothermal AFM and is designed to handle pressures up to 100 atm at temperatures up to ~ 350 K. A standard optically-based cantilever deflection detection system was chosen. When imaging in compressible supercritical fluids such as scCO2, precise control of pressure and temperature in the fluid cell is the primary technical challenge. Noise levels and imaging resolution depend on minimization of fluid density fluctuations thatmore » change the fluid refractive index and hence the laser path. We demonstrate with our apparatus in-situ atomic scale imaging of a calcite (CaCO3) mineral surface in scCO2; both single, monatomic steps and dynamic processes occurring on the (10¯14) surface are presented. This new AFM provides unprecedented in-situ access to interfacial phenomena at solid-fluid interfaces under pressure.« less