Decomposing anharmonicity and mode-coupling from matrix effects in the IR spectra of matrix-isolated carbon dioxide and methane

Dinu, Dennis F.; Podewitz, Maren; Grothe, Hinrich; Loerting, Thomas; Liedl, Klaus R.

doi:10.1039/d0cp02121k

Cited by 10 publications

(19 citation statements)

References 130 publications

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“…To simplify the procedure for the reduction of CO 2 methanation catalysts, the activation of Ni-Al 2 O 3 -SSC and NIAP-07-01 catalysts in a flow of reaction mixture (H 2 :CO 2 :Ar = 16:4:80) was studied. Since CO 2 and CH 4 have characteristic absorption bands [63] a qualitative assessment of the nickel reduction with varying the temperature of activation was performed by FTIR spectroscopy.…”

Section: Nio + H2 → Ni + H2omentioning

confidence: 99%

CO2 Methanation: Nickel–Alumina Catalyst Prepared by Solid-State Combustion

et al. 2021

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The development of solvent-free methods for the synthesis of catalysts is one of the main tasks of green chemistry. A nickel–alumina catalyst for CO2 methanation was synthesized by solid-state combustion method using hexakis-(imidazole) nickel (II) nitrate complex. Using X-ray Powder Diffraction (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Hydrogen temperature-programmed reduction (H2-TPR), it was shown that the synthesized catalyst is characterized by the localization of easily reduced nickel oxide on alumina surface. This provided low-temperature activation of the catalyst in the reaction mixture containing 4 vol% CO2. In addition, the synthesized catalyst had higher activity in low-temperature CO2 methanation compared to industrial NIAP-07-01 catalyst, which contained almost three times more hard-to-reduce nickel–aluminum spinel. Thus, the proposed approaches to the synthesis and activation of the catalyst make it possible to simplify the catalyst preparation procedure and to abandon the use of solvents, which must be disposed of later on.

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Section: Nio + H2 → Ni + H2omentioning

confidence: 99%

CO2 Methanation: Nickel–Alumina Catalyst Prepared by Solid-State Combustion

et al. 2021

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“…We performed multiple MI-IR experiments on stable, small molecules, such as water [29], carbon dioxide, and methane [30], fluoroethane [74], methanol, and others. In all those studies, we use argon and neon as host systems and utilize various dilutions and temperature changes to learn about the influence of matrix effects.…”

Section: Case Studies On the Synergy Of Mi-ir And Vscf/ Vcimentioning

confidence: 99%

“…However, especially the history of spectral assignments of CO 2 , CH 4 , and CD 4 shows that the interpretation of their MI-IR spectra is very controversial. We have recently shown that the matrix effects for these two molecules in different host materials are far from being systematic [30] and that methane might also rotate in Ne matrices.…”

Section: Carbon Dioxide and Methane: Matrix Effects Are Not Systematicmentioning

confidence: 99%

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On the synergy of matrix-isolation infrared spectroscopy and vibrational configuration interaction computations

et al. 2020

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The key feature of matrix-isolation infrared (MI-IR) spectroscopy is the isolation of single guest molecules in a host system at cryogenic conditions. The matrix mostly hinders rotation of the guest molecule, providing access to pure vibrational features. Vibrational self-consistent field (VSCF) and configuration interaction computations (VCI) on ab initio multimode potential energy surfaces (PES) give rise to anharmonic vibrational spectra. In a single-sourced combination of these experimental and computational approaches, we have established an iterative spectroscopic characterization procedure. The present article reviews the scope of this procedure by highlighting the strengths and limitations based on the examples of water, carbon dioxide, methane, methanol, and fluoroethane. An assessment of setups for the construction of the multimode PES on the example of methanol demonstrates that CCSD(T)-F12 level of theory is preferable to compute (a) accurate vibrational frequencies and (b) equilibrium or vibrationally averaged structural parameters. Our procedure has allowed us to uniquely assign unknown or disputed bands and enabled us to clarify problematic spectral regions that are crowded with combination bands and overtones. Besides spectroscopic assignment, the excellent agreement between theory and experiment paves the way to tackle questions of rather fundamental nature as to whether or not matrix effects are systematic, and it shows the limits of conventional notations used by spectroscopists.

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“…Thus, we investigate the IR spectrum of carbon dioxide using matrix isolation to quench rotational transitions and use anharmonic calculations to assign all observed vibrational transitions. Previously, we successfully assigned all CO 2 monomer bands, 11 where we also provided a short review of the theoretical and experimental spectroscopy of carbon dioxide and its dimer. For a detailed review on computational studies on the (CO 2 ) 2 dimer and also recent calculations we refer to Maystrovsky et al, 12 who demonstrated that variational calculations using a tailor-made potential energy surface for the dimer on explicitly correlated coupled cluster theory yield excellent results.…”

Section: Introductionmentioning

confidence: 99%

Increase of Radiative Forcing through Midinfrared Absorption by Stable CO₂ Dimers?

et al. 2022

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We performed matrix-isolation infrared (MI-IR) spectroscopy of carbon dioxide monomers, CO 2 , and dimers, (CO 2 ) 2 , trapped in neon and in air. On the basis of vibration configuration interaction (VCI) calculations accounting for mode coupling and anharmonicity, we identify additional infrared-active bands in the MI-IR spectra due to the (CO 2 ) 2 dimer. These bands are satellite bands next to the established CO 2 monomer bands, which appear in the infrared window of Earth’s atmosphere at around 4 and 15 μm. In a systematic carbon dioxide mixing ratio study using neon matrixes, we observe a significant fraction of the dimer at mixing ratios above 300 ppm, with a steep increase up to 1000 ppm. In neon matrix, the dimer increases the IR absorbance by about 15% at 400 ppm compared to the monomer absorbance alone. This suggests a high fraction of the (CO 2 ) 2 dimer in our matrix experiments. In atmospheric conditions, such increased absorbance would significantly amplify radiative forcings and, thus, the greenhouse warming. To enable a comparison of our laboratory experiment with various atmospheric conditions (Earth, Mars, Venus), we compute the thermodynamics of the dimerization accordingly. The dimerization is favored at low temperatures and/or high carbon dioxide partial pressures. Thus, we argue that matrix isolation does not trap the gas composition “as is”. Instead, the gas is precooled to 40 K, where CO 2 dimerizes before being trapped in the matrix, already at very low carbon dioxide partial pressures. In the context of planetary atmospheres, our results improve understanding of the greenhouse effect for planets of rather thick CO 2 atmospheres such as Venus, where a significant fraction of the (CO 2 ) 2 dimer can be expected. There, the necessity of including the mid-IR absorption by stable (CO 2 ) 2 dimers in databases used for modeling radiative forcing, such as HITRAN, arises.

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Decomposing anharmonicity and mode-coupling from matrix effects in the IR spectra of matrix-isolated carbon dioxide and methane

Abstract: A combined experimental and computational approach revealed similarities and differences in the vibrational signature of matrix-isolated carbon dioxide and methane.

Cited by 10 publications

References 130 publications

CO2 Methanation: Nickel–Alumina Catalyst Prepared by Solid-State Combustion

CO2 Methanation: Nickel–Alumina Catalyst Prepared by Solid-State Combustion

On the synergy of matrix-isolation infrared spectroscopy and vibrational configuration interaction computations

Increase of Radiative Forcing through Midinfrared Absorption by Stable CO₂ Dimers?

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Decomposing anharmonicity and mode-coupling from matrix effects in the IR spectra of matrix-isolated carbon dioxide and methane

Abstract: A combined experimental and computational approach revealed similarities and differences in the vibrational signature of matrix-isolated carbon dioxide and methane.

Cited by 10 publications

References 130 publications

CO2 Methanation: Nickel–Alumina Catalyst Prepared by Solid-State Combustion

CO2 Methanation: Nickel–Alumina Catalyst Prepared by Solid-State Combustion

On the synergy of matrix-isolation infrared spectroscopy and vibrational configuration interaction computations

Increase of Radiative Forcing through Midinfrared Absorption by Stable CO2 Dimers?

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Increase of Radiative Forcing through Midinfrared Absorption by Stable CO₂ Dimers?