Spectroscopy of Hydrothermal Reactions. Part XI: Infrared Absorptivity of CO<sub>2</sub> and N<sub>2</sub>O in Water at Elevated Temperature and Pressure

Maiella, P. G.; Schoppelrei, J. W.; Brill, T. B.

doi:10.1366/0003702991946578

Cited by 40 publications

(62 citation statements)

References 26 publications

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“…Only the asymmetric stretch of aqueous CO 2 centered at 2343 cm −1 was observed in the band pass of sapphire windows. The band area of CO 2 was converted to concentration by using the Beer–Lambert law and the previously determined molar absorptivity of aqueous CO 2 28. The weighted least‐squares regression 29 was performed in which the statistical weight was set to be 1/σ 2 , where σ is the standard deviation of the variables.…”

Section: Methodsmentioning

confidence: 99%

Spectroscopy of hydrothermal reactions, 19: pH and salt dependence of decarboxylation of α‐alanine at 280–330°C in an FT‐IR spectroscopy flow reactor

Li¹,

Wang²,

Klein³

et al. 2002

Int J of Chemical Kinetics

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The spontaneous decarboxylation of 0.5 m aqueous α-alanine solutions as a function of pH (1-9 at 320 • C, where neutrality is approximately 6) was determined with a flow reactor at 280-330 • C and 275 bar by FT-IR spectroscopy. The kinetics for the cationic and anionic forms have not been previously reported. The rate constants for the cationic form [CH 3 (NH 3 + )CHCO 2 H], the anionic form [CH 3 (NH 2 )CHCO 2 − ], and the zwitterion form [CH 3 (NH 3 + )CHCO 2 − ] were obtained and followed the first-order rate law. The rate of decarboxylation of the zwitterion is three times greater than that of the cationic and anionic forms in the temperature and pH ranges of study. The corresponding Arrhenius parameters were determined and compared with previously reported data. The addition of KCl (1 and 2 m) at the natural pH of α-alanine resulted in a reduction of the decarboxylation rate, suggesting that the transition state is less polar than the zwitterion and/or that the activity of the zwitterion has been reduced. The α-alanine solution is therefore somewhat more robust in solutions of high ionic strength, such as seawater, than it is in pure water.

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Section: Methodsmentioning

confidence: 99%

Spectroscopy of hydrothermal reactions, 19: pH and salt dependence of decarboxylation of α‐alanine at 280–330°C in an FT‐IR spectroscopy flow reactor

Li¹,

Wang²,

Klein³

et al. 2002

Int J of Chemical Kinetics

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show abstract

“…To obtain the kinetic parameters, the band area of CO 2 was converted to concentration at each condition by using the Beer-Lambert Law and the previously determined molar absorptivity of aqueous CO 2 . 15 Weighted least-squares regression 16 was performed in which the statistical weight was set to be 1/σ 2 , where σ is the standard deviation of the variables.…”

Section: Methodsmentioning

confidence: 99%

Spectroscopy of Hydrothermal Solutions 18: pH-Dependent Kinetics of Itaconic Acid Reactions in Real Time

Brill

2001

J. Phys. Chem. A

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The kinetics of decarboxylation of the R-substituted acrylic acid itaconic acid were analyzed at 280-330°C, 275 bar, and solution pH 25 ) 0.8-5.75 using an FTIR spectroscopy flow reactor. As the pH was increased, the observed rate constant initially decreased to a minimum at pH 25 ) 1.82, then increased and reached its maximum at pH 25 ) 3.75, and then decreased again up to the limit of study at pH 25 ) 5.75. The decarboxylation rate depends on the molecular form of itaconic acid in the order of itaconate monoanion > protonated itaconic acid > neutral itaconic acid ≈ itaconate dianion. Insight into possible reasons for this trend was obtained from geometry-optimized structures using density functional theory with the B3LYP method at the 6-31+G* level.

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“…The carbon dioxide concentration was kept sufficiently low that vibrational excitation transfer between adjacent molecules was statistically unlikely to occur. Using the extinction coefficient of carbon dioxide in water 40 and aluminosilicate glasses, 41 the concentration was estimated to be around 2500 ion pairs per carbon dioxide from the background-subtracted FTIR spectrum (Section III A).…”

Section: A Sample Preparationmentioning

confidence: 99%

Carbon dioxide in an ionic liquid: Structural and rotational dynamics

Giammanco

Kramer

Yamada

et al. 2016

The Journal of Chemical Physics

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Ionic liquids (ILs), which have widely tunable structural motifs and intermolecular interactions with solutes, have been proposed as possible carbon capture media. To inform the choice of an optimal ionic liquid system, it can be useful to understand the details of dynamics and interactions on fundamental time scales (femtoseconds to picoseconds) of dissolved gases, particularly carbon dioxide (CO2), within the complex solvation structures present in these uniquely organized materials. The rotational and local structural fluctuation dynamics of CO2 in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EmimNTf2) were investigated by using ultrafast infrared spectroscopy to interrogate the CO2 asymmetric stretch. Polarization-selective pump probe measurements yielded the orientational correlation function of the CO2 vibrational transition dipole. It was found that reorientation of the carbon dioxide occurs on 3 time scales: 0.91 ± 0.03, 8.3 ± 0.1, 54 ± 1 ps. The initial two are attributed to restricted wobbling motions originating from a gating of CO2 motions by the IL cations and anions. The final (slowest) decay corresponds to complete orientational randomization. Two-dimensional infrared vibrational echo (2D IR) spectroscopy provided information on structural rearrangements, which cause spectral diffusion, through the time dependence of the 2D line shape. Analysis of the time-dependent 2D IR spectra yields the frequency-frequency correlation function (FFCF). Polarization-selective 2D IR experiments conducted on the CO2 asymmetric stretch in the parallel- and perpendicular-pumped geometries yield significantly different FFCFs due to a phenomenon known as reorientation-induced spectral diffusion (RISD), revealing strong vector interactions with the liquid structures that evolve slowly on the (independently measured) rotation time scales. To separate the RISD contribution to the FFCF from the structural spectral diffusion contribution, the previously developed first order Stark effect RISD model is reformulated to describe the second order (quadratic) Stark effect--the first order Stark effect vanishes because CO2 does not have a permanent dipole moment. Through this analysis, we characterize the structural fluctuations of CO2 in the ionic liquid solvation environment, which separate into magnitude-only and combined magnitude and directional correlations of the liquid's time dependent electric field. This new methodology will enable highly incisive comparisons between CO2 dynamics in a variety of ionic liquid systems.

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Spectroscopy of Hydrothermal Reactions. Part XI: Infrared Absorptivity of CO₂ and N₂O in Water at Elevated Temperature and Pressure

Cited by 40 publications

References 26 publications

Spectroscopy of hydrothermal reactions, 19: pH and salt dependence of decarboxylation of α‐alanine at 280–330°C in an FT‐IR spectroscopy flow reactor

Spectroscopy of hydrothermal reactions, 19: pH and salt dependence of decarboxylation of α‐alanine at 280–330°C in an FT‐IR spectroscopy flow reactor

Spectroscopy of Hydrothermal Solutions 18: pH-Dependent Kinetics of Itaconic Acid Reactions in Real Time

Carbon dioxide in an ionic liquid: Structural and rotational dynamics

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Spectroscopy of Hydrothermal Reactions. Part XI: Infrared Absorptivity of CO2 and N2O in Water at Elevated Temperature and Pressure

Cited by 40 publications

References 26 publications

Spectroscopy of hydrothermal reactions, 19: pH and salt dependence of decarboxylation of α‐alanine at 280–330°C in an FT‐IR spectroscopy flow reactor

Spectroscopy of hydrothermal reactions, 19: pH and salt dependence of decarboxylation of α‐alanine at 280–330°C in an FT‐IR spectroscopy flow reactor

Spectroscopy of Hydrothermal Solutions 18: pH-Dependent Kinetics of Itaconic Acid Reactions in Real Time

Carbon dioxide in an ionic liquid: Structural and rotational dynamics

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Spectroscopy of Hydrothermal Reactions. Part XI: Infrared Absorptivity of CO₂ and N₂O in Water at Elevated Temperature and Pressure