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CO2 solubility data in the natural formation brine, synthetic formation brine, and synthetic NaCl+CaCl2 brine were collected at the pressures from 100 to 200 bar, temperatures from 323 to 423 K. Experimental results demonstrate that the CO2 solubility in the synthetic formation brines can be reliably represented by that in the synthetic NaCl+CaCl2 brines. We extended our previously developed model (PSUCO2) to calculate CO2 solubility in aqueous mixed-salt solution by using the additivity rule of the Setschenow coefficients of the individual ions (Na(+), Ca(2+), Mg(2+), K(+), Cl(-), and SO4(2-)). Comparisons with previously published models against the experimental data reveal a clear improvement of the proposed PSUCO2 model. Additionally, the path of the maximum gradient of the CO2 solubility contours divides the P-T diagram into two distinct regions: in Region I, the CO2 solubility in the aqueous phase decreases monotonically in response to increased temperature; in region II, the behavior of the CO2 solubility is the opposite of that in Region I as the temperature increases.

Heterostructures between montmorillonite and embedded alpha-Fe2O3 nanoparticles are explored to create new hybrid particles with high magnetic response and magnetic-field induced tunability. α-Fe2O3 nanoparticles are hybridized to montmorillonite clays by using an intercalation technique. Also, stable aqueous fluids consisting of the heterostructured particles are prepared and the rheology of the fluids under external magnetic field is examined. When α-Fe2O3 a nanoparticles are embedded in the interlayer space of montmorillonite clays, the magnetization per Fe atom increases at most 60 times. This unique combination of the magnetization and the coercivity is traced to the suppressed growth of embedded α-Fe2O3 nanoparticles by the aluminosilicate layers, leading to the size control, anisotropic magnetic interaction, and uniaxial stress of two-dimensionally distributed α-Fe2O3 nanoparticles. Furthermore, high magnetization of heterostructured particles leads to strong dependence of fluids' viscosity on the external magnetic field. The present study indicates that the new heterostructured particles have unique magnetic fielddependent properties that are not attainable in individual clay or iron oxide particles.

Experiments were conducted to determine the solubility of CO2 in a natural brine solution of the Oriskany formation under elevated temperature and pressure conditions. These data were collected at temperatures of 22 and 75 degrees C and pressures between 100 and 450 bar. Experimentally determined data were compared with CO2 solubility predictions using a model developed by Duan and Sun (Chem. Geol. 2003, 193, 257-271). Model results compare well with Oriskany brine CO2 solubility data collected experimentally, suggesting that the Duan and Sun model is a reliable tool for estimating solution CO2 capacity in high salinity aquifers in the temperature and pressure range evaluated. The capacity for the Oriskany formation to sequester dissolved CO2 was calculated using results of the solubility models, estimation of the density of CO2 saturated brine, and available geographic information system (GIS) information on the formation depth and thickness. Results indicate that the Oriskany formation can hold approximately 0.36 gigatonnes of dissolved CO2 if the full basin is considered. When only the region where supercritical CO2 can exist (temperatures greaterthan 31 degrees C and pressures greaterthan 74 bar) is considered, the capacity of the Oriskany formation to sequester dissolved CO2 is 0.31 gigatonnes. The capacity estimate considering the potential to sequester free-phase supercritical CO2 if brine were displaced from formation pore space is 8.8 gigatonnes in the Oriskany formation.

Experiments were conducted to explore the concept of beneficially utilizing mixtures of caustic bauxite residue slurry (pH 13) and produced oil-field brine to sequester carbon dioxide from flue gas generated from industrial point sources. Data presented herein provide a preliminary assessment of the overall feasibility of this treatment concept. The Carbonation capacity of bauxite residue/brine mixtures was considered over the full range of reactant mixture combinations in 10% increments by volume. A bauxite residue/brine mixture of 90/10 by volume exhibited a CO2 sequestration capacity of greater than 9.5 g/L when exposed to pure CO2 at 20 °C and 0.689 MPa (100 psig). Dawsonite and calcite formation were predicted to be the dominant products of bauxite/brine mixture carbonation. It is demonstrated that CO2 sequestration is augmented by adding bauxite residue as a caustic agent to acidic brine solutions and that trapping is accomplished through both mineralization and solubilization. The product mixture s...

The adsorption and desorption of CO2 and SO2 on an amine-grafted SBA-15 sorbent has been studied by in situ infrared spectroscopy coupled with mass spectrometry. CO2 adsorbed on an amine-grafted sorbent as carbonates and bicarbonates, while SO2 adsorbed as sulfates and sulfites. The CO2 adsorption capacity of the amine-grafted sorbent was almost twice as much as that of a commercial sorbent. The adsorption of CO2 in the presence of H2O and D2O shows an isotopic shift in the IR frequency of adsorbed carbonate and bicarbonate bands, revealing that water plays a role in the CO2 adsorption on amine-grafted sorbents. Although the rate of adsorption of SO2 was slower than that of CO2, the adsorbed S surface species is capable of blocking the active amine sites for CO2 adsorption. A temperature-programmed degradation study of the amine-grafted sorbent showed that the surface amine species are stable up to 250 °C in air.

The adsorption and desorption of CO2 on diamine-grafted SBA-15 have been studied by infrared spectroscopy coupled with mass spectrometry. Diamine was grafted onto the SBA-15 surface by the reaction of [N-(2-aminoethyl)-3-aminopropyl]trimethoxysilane with the surface OH. CO2 is adsorbed on the diamine-grafted SBA-15 as bidentate carbonate and bidentate and monodentate bicarbonates at 25 °C. Bidentate carbonate and monodentate bicarbonates are the major surface species formed and decomposed during the concentration-swing adsorption/desorption process at 25 °C. Temperature-programmed desorption revealed that the monodentate and bidentate bicarbonates bound stronger to the diamine-grafted SBA-15 surface than the bidentate carbonate. The amount of CO2 desorbed from the carbonate and bicarbonate between 30 and 120 °C is 2 times more than that of CO2 adsorbed/desorbed during each cycle of the concentration-swing adsorption/desorption. Desorption at 120 °C removes the majority of the captured CO2 and regenerates ...

CO2 adsorption/desorption on SBA-15 grafted with γ-(aminopropyl)triethoxysilane (APTS) has been studied by infrared spectroscopy coupled with temperature-programmed desorption. SBA-15, a mesoporous silica material with a uniform pore size of 21 nm and a surface area of 200−230 m2/g, provides an OH functional group for grafting of γ-(aminopropyl)triethoxysilane. The amine-grafted SBA-15 adsorbed CO2 as carbonates and bicarbonates with a total capacity of 200−400 μmol/g. The heat of CO2 desorption was determined to be 3.2−4.5 kJ/mol in the presence of H2O and 6.6−11.0 kJ/mol in the absence of H2O during temperature-programmed desorption. Repeated CO2 adsorption/desorption CO2 cycles shifted the desorption peak temperature downward and decreased the heat of CO2 adsorption.

Powder and lumps of the Argonne Premium Upper Freeport coal were compared in a 9-month-long CO2 sorption−desorption study. On the basis of the slope analysis, CO2 induced the lumps swelling by 7%. The powder swelled by 8% and then rapidly shrank by 3% on desorption. This was verified by a “single point” injection of helium and the pressure-and-density technique, which was sufficiently sensitive. Low-pressure Langmuir-fit parameters suggest that the microporous textures of the powder and lumps are similar. The samples demonstrated greatly increased sticking coefficients and a slightly larger number of the “sorption ready” sites, after the CO2-induced swelling and structural rearrangement resulted in variable degrees of the matrix shrinkage. No permanent changes in the void volume and dry mass were detected after complete desorption. The observed hysteresis in sorption−desorption behavior of both samples upon the approach to the CO2 density fluctuation ridge is interpreted as a contribution of condensation ...

The application of the three-phase slurry reactor system for coal liquefaction processing and chemical industries has recently received considerable attention. To design and efficiently operate a three-phase slurry reactor, the degree of dispersion of the solid (catalyst) in the reactor must be understood and controlled. An ultrasonic technique was developed to measure the concentration of solids in an autoclave reactor. Preliminary measurements were conducted on slurries consisting of molten paraffin wax, glass beads, and nitrogen bubbles at 189 C. The data show that the velocity and attenuation of the sound are well-defined functions of the solid and gas concentrations in the molten wax. The results suggest possibilities for directly measuring solids concentration during operation of a three-phase slurry reactor.

For heterogeneous catalysis, ordinary differential equations in time can be used to interpret transient tracer data obtained in a continuous stirred tank reactor or gradientless reactor in which a steady-state reaction is occurring. The same procedure is often used for plug-flow reactor modeling. However, for transient tracing data obtained with a plug-flow reactor operating under differential conversion, it is necessary to use a set of partial differential equations involving distance through the reactor as well as time. In this paper, the authors present a case study of methanation on a nickel catalyst to illustrate the modeling procedure needed to estimate the desired parameters.