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Abstract
Raman spectroscopy is a promising tool for measuring the composition of natural gas. However, to obtain high measurement accuracy, it is necessary to take into account changes in the spectral characteristics of methane, since its spectrum overlaps the characteristic bands of other species. In this study we present a technique for natural gas analysis based on polarized Raman spectroscopy. It is shown that the use of only isotropic components of spectra simplifies the procedure for extracting concentrations and improves the measurement accuracy of components whose spectral bands are significantly overlapped in conventional Raman spectra. The presented technique will be very useful both in the field of analysis of various multicomponent gas mixtures and in the field of measuring the isotopic composition of molecules.
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Affiliation(s)
- Dmitry Petrov
- Institute of Monitoring of Climatic and Ecological Systems, Tomsk 634055, Russia
- Tomsk State University, Tomsk 634050, Russia
| | - Ivan Matrosov
- Institute of Monitoring of Climatic and Ecological Systems, Tomsk 634055, Russia
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Singh J, Muller A. High-Precision Trace Hydrogen Sensing by Multipass Raman Scattering. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23115171. [PMID: 37299898 DOI: 10.3390/s23115171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 05/18/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023]
Abstract
Despite its growing importance in the energy generation and storage industry, the detection of hydrogen in trace concentrations remains challenging, as established optical absorption methods are ineffective in probing homonuclear diatomics. Besides indirect detection approaches using, e.g., chemically sensitized microdevices, Raman scattering has shown promise as an alternative direct method of unambiguous hydrogen chemical fingerprinting. We investigated the suitability of feedback-assisted multipass spontaneous Raman scattering for this task and examined the precision with which hydrogen can be sensed at concentrations below 2 parts per million. A limit of detection of 60, 30, and 20 parts per billion was obtained at a pressure of 0.2 MPa in a 10-min-long, 120-min-long, and 720-min-long measurement, respectively, with the lowest concentration probed being 75 parts per billion. Various methods of signal extraction were compared, including asymmetric multi-peak fitting, which allowed the resolution of concentration steps of 50 parts per billion, determining the ambient air hydrogen concentration with an uncertainty level of 20 parts per billion.
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Affiliation(s)
- Jaspreet Singh
- Physics Department, University of South Florida, Tampa, FL 33620, USA
| | - Andreas Muller
- Physics Department, University of South Florida, Tampa, FL 33620, USA
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Tanichev AS, Petrov DV. Pressure broadening in Raman spectra of CH 4-N 2, CH 4-CO 2, and CH 4-C 2H 6 gas mixtures. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 291:122396. [PMID: 36696859 DOI: 10.1016/j.saa.2023.122396] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 06/17/2023]
Abstract
Different molecular environments change the spectrum of a given gas sample involved in a mixture compared to the spectrum of a pure gas. It is necessary to account for this effect to improve the accuracy of the analysis of the natural gas composition by Raman spectroscopy. First, the change in the main components of natural gas (methane, nitrogen, carbon dioxide, and ethane) must be considered. This work is devoted to the mutual influence of CH4-N2, CH4-CO2, and CH4-C2H6 on their characteristic Raman bands in the range of 300-2500 cm-1. The half-width and asymmetry of the Q branches of N2, CO2, and C2H6 as a function of methane concentration were obtained in the range of 1-50 bar. The averaged broadening coefficients of the rotational-vibrational lines of the ν2 band of CH4 perturbed by N2, CO2, and C2H6 are measured. A high-sensitivity spectrometer with a resolution of 0.5 cm-1 based on spontaneous Raman scattering was used to obtain reliable results. The algorithm and all the necessary parameters for simulating the effect of various molecular environments on the Raman bands of the main components of natural gas are presented.
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Affiliation(s)
- Aleksandr S Tanichev
- Laboratory of Ecological Instrumentation, Institute of Monitoring of Climatic and Ecological Systems, 634055 Tomsk, Russia.
| | - Dmitry V Petrov
- Laboratory of Ecological Instrumentation, Institute of Monitoring of Climatic and Ecological Systems, 634055 Tomsk, Russia; Department of Optics and Spectroscopy, Tomsk State University, 634050 Tomsk, Russia
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Tanichev AS, Petrov DV. Broadening of the ν 2 Raman Band of CH 4 by C 3H 8 and C 4H 10. Molecules 2023; 28:molecules28083365. [PMID: 37110599 PMCID: PMC10146573 DOI: 10.3390/molecules28083365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/05/2023] [Accepted: 04/09/2023] [Indexed: 04/29/2023] Open
Abstract
Raman spectroscopy is a promising method for the analysis of natural gas. It is necessary to account for the broadening effects on spectral lines to improve measurement accuracy. In this study, the broadening coefficients for methane lines in the region of the ν2 band perturbed by propane, n-butane, and isobutane at room temperature were measured. We estimated the measurement errors of the concentration of oxygen and carbon dioxide in the case of neglecting the broadening effects on the methane spectrum by the pressure of C2-C6 alkanes. The obtained data are suited for the correct simulation of the methane spectrum in the hydrocarbon-bearing gases and can be used to improve the accuracy of the analysis of natural gas by Raman spectroscopy.
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Affiliation(s)
- Aleksandr S Tanichev
- Institute of Monitoring of Climatic and Ecological Systems, Siberian Branch of the Russian Academy of Sciences, 634055 Tomsk, Russia
| | - Dmitry V Petrov
- Institute of Monitoring of Climatic and Ecological Systems, Siberian Branch of the Russian Academy of Sciences, 634055 Tomsk, Russia
- Department of Optics and Spectroscopy, Tomsk State University, 634050 Tomsk, Russia
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Mazza F, Thornquist O, Castellanos L, Butterworth T, Richard C, Boudon V, Bohlin A. The ro-vibrational ν 2 mode spectrum of methane investigated by ultrabroadband coherent Raman spectroscopy. J Chem Phys 2023; 158:094201. [PMID: 36889980 DOI: 10.1063/5.0138803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023] Open
Abstract
We present the first experimental application of coherent Raman spectroscopy (CRS) on the ro-vibrational ν2 mode spectrum of methane (CH4). Ultrabroadband femtosecond/picosecond (fs/ps) CRS is performed in the molecular fingerprint region from 1100 to 2000 cm-1, employing fs laser-induced filamentation as the supercontinuum generation mechanism to provide the ultrabroadband excitation pulses. We introduce a time-domain model of the CH4 ν2 CRS spectrum, including all five ro-vibrational branches allowed by the selection rules Δv = 1, ΔJ = 0, ±1, ±2; the model includes collisional linewidths, computed according to a modified exponential gap scaling law and validated experimentally. The use of ultrabroadband CRS for in situ monitoring of the CH4 chemistry is demonstrated in a laboratory CH4/air diffusion flame: CRS measurements in the fingerprint region, performed across the laminar flame front, allow the simultaneous detection of molecular oxygen (O2), carbon dioxide (CO2), and molecular hydrogen (H2), along with CH4. Fundamental physicochemical processes, such as H2 production via CH4 pyrolysis, are observed through the Raman spectra of these chemical species. In addition, we demonstrate ro-vibrational CH4 v2 CRS thermometry, and we validate it against CO2 CRS measurements. The present technique offers an interesting diagnostics approach to in situ measurement of CH4-rich environments, e.g., in plasma reactors for CH4 pyrolysis and H2 production.
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Affiliation(s)
- Francesco Mazza
- Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands
| | - Ona Thornquist
- Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands
| | - Leonardo Castellanos
- Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands
| | - Thomas Butterworth
- Faculty of Science and Engineering, Maastricht University, Paul Henri Spaaklaan 1, 6229 GS Maastricht, The Netherlands
| | - Cyril Richard
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université Bourgogne Franche-Comté, 9 Avenue Alain Savary, BP 47 870, F-21078 Dijon Cedex, France
| | - Vincent Boudon
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université Bourgogne Franche-Comté, 9 Avenue Alain Savary, BP 47 870, F-21078 Dijon Cedex, France
| | - Alexis Bohlin
- Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands
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Raman Natural Gas Analyzer: Effects of Composition on Measurement Precision. SENSORS 2022; 22:s22093492. [PMID: 35591181 PMCID: PMC9099776 DOI: 10.3390/s22093492] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 04/29/2022] [Accepted: 05/01/2022] [Indexed: 11/17/2022]
Abstract
Raman spectroscopy is a promising method for analyzing natural gas due to its high measurement speed and the potential to monitor all molecular components simultaneously. This paper discusses the features of measurements of samples whose composition varies over a wide range (0.005-100%). Analysis of the concentrations obtained during three weeks of experiments showed that their variation is within the error caused by spectral noise. This result confirms that Raman gas analyzers can operate without frequent calibrations, unlike gas chromatographs. It was found that a variation in the gas composition can change the widths of the spectral lines of methane. As a result, the measurement error of oxygen concentration can reach 200 ppm. It is also shown that neglecting the measurement of pentanes and n-hexane leads to an increase in the calculated concentrations of other alkanes and to errors in the density and heating value of natural gas.
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Knebl A, Domes C, Domes R, Wolf S, Popp J, Frosch T. Response to Comment on Hydrogen and C2-C6 Alkane Sensing in Complex Fuel Gas Mixtures with Fiber-Enhanced Raman Spectroscopy. Anal Chem 2021; 93:16285-16287. [PMID: 34807580 DOI: 10.1021/acs.analchem.1c04606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andreas Knebl
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, 07745 Jena, Germany
| | - Christian Domes
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, 07745 Jena, Germany
| | - Robert Domes
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, 07745 Jena, Germany
| | - Sebastian Wolf
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, 07745 Jena, Germany
| | - Juergen Popp
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, 07745 Jena, Germany.,Institute of Physical Chemistry, Friedrich Schiller University, 07743 Jena, Germany.,Abbe Center of Photonics, Friedrich Schiller University, 07743 Jena, Germany
| | - Torsten Frosch
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, 07745 Jena, Germany.,Abbe Center of Photonics, Friedrich Schiller University, 07743 Jena, Germany.,Biophotonics and Biomedical Engineering Group, Technical University Darmstadt, Merckstraße 25, 64283 Darmstadt, Germany
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Knebl A, Domes C, Domes R, Wolf S, Popp J, Frosch T. Hydrogen and C2-C6 Alkane Sensing in Complex Fuel Gas Mixtures with Fiber-Enhanced Raman Spectroscopy. Anal Chem 2021; 93:10546-10552. [PMID: 34297525 DOI: 10.1021/acs.analchem.1c01500] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Power-to-gas is a heavily discussed option to store surplus electricity from renewable sources. Part of the generated hydrogen could be fed into the gas grid and lead to fluctuations in the composition of the fuel gas. Consequently, both operators of transmission networks and end users would need to frequently monitor the gas to ensure safety as well as optimal and stable operation. Currently, gas chromatography-based analysis methods are the state of the art. However, these methods have several downsides for time-resolved and distributed application and Raman gas spectroscopy is favorable for future point-of-use monitoring. Here, we demonstrate that fiber-enhanced Raman gas spectroscopy (FERS) enables the simultaneous detection of all relevant gases, from major (methane, CH4; hydrogen, H2) to minor (C2-C6 alkanes) fuel gas components. The characteristic peaks of H2 (585 cm-1), CH4 (2917 cm-1), isopentane (765 cm-1), i-butane (798 cm-1), n-butane (830 cm-1), n-pentane (840 cm-1), propane (869 cm-1), ethane (993 cm-1), and n-hexane (1038 cm-1) are well resolved in the broadband spectra acquired with a compact spectrometer. The fiber enhancement achieved in a hollow-core antiresonant fiber enables highly sensitive measurements with limits of detection between 90 and 180 ppm for different hydrocarbons. Both methane and hydrogen were quantified with high accuracy with average relative errors of 1.1% for CH4 and 1.5% for H2 over a wide concentration range. These results show that FERS is ideally suited for comprehensive fuel gas analysis in a future, where regenerative sources lead to fluctuations in the composition of gas.
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Affiliation(s)
- Andreas Knebl
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, Jena 07745, Germany
| | - Christian Domes
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, Jena 07745, Germany
| | - Robert Domes
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, Jena 07745, Germany
| | - Sebastian Wolf
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, Jena 07745, Germany
| | - Juergen Popp
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, Jena 07745, Germany.,Institute of Physical Chemistry & Abbe Center of Photonics, Friedrich Schiller University, Jena 07745, Germany
| | - Torsten Frosch
- Leibniz Institute of Photonic Technology Jena, Albert Einstein Strasse 9, Jena 07745, Germany.,Institute of Physical Chemistry & Abbe Center of Photonics, Friedrich Schiller University, Jena 07745, Germany.,Biophotonics and Biomedical Engineering Group, Technical University Darmstadt, Merckstraße 25, Darmstadt 64283, Germany
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