This work extends our experimentally studies with simulation of Titan's atmosphere by atmospheric glow discharge. This work is devoted to estimate the influence of CO2 and/or CO on reactivity in the Titan's atmosphere. The exploration of planetary atmosphere is being advanced by the exciting results of the Cassin-Huygens mission to Saturn and Titan, its most famous moon. Most of the studies were mainly interested in the reactivity of the N2-CH4 gaseous mixture and with the primary products of reactions, but the atmosphere of Titan also contains oxygenated volatile species

Krcma, F.

Mason, Nigel

Matejcik, S.

Mazankova, V.

Torokova, L.

This work extends our experimentally studies with simulation of Titan’s atmosphere by atmospheric glow discharge. This work is devoted to estimate the influence of CO2 and/or CO on reactivity in the Titan’s atmosphere. The exploration of planetary atmosphere is being advanced by the exciting results of the Cassin-Huygens mission to Saturn and Titan, its most famous moon. Most of the studies were mainly interested in the reactivity of the N2-CH4 gaseous mixture and with the primary products of reactions, but the atmosphere of Titan also contains oxygenated volatile species

Mason, N. J.

CTU Open Journal Systems (Czech Technical University, Prague / České vysoké učení technické v Praze)

Torokova L. et al.: The Influence of Admixtures on the Composition of Products by Nitrogen-Methane…  Plasma Physics and Technology 2015, 2, 1, 88-91 The Influence of Admixtures on the Composition of Products by Nitrogen-Methane Atmospheric Glow Discharge Torokova L.1,2, Mazankova V.1, Krcma F.1, Mason N.J.2, Matejcik S.3 1Faculty of Chemistry, Brno University of Technology, Purkynova 119, 612 00, Brno, Czech Republic 2Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA, UK 3Department of Experimental Physics, Comenius University, Mlynska dolina F-2, 842 48 Bratislava, Slovakia This work extends our experimentally studies with simulation of Titan’s atmosphere by atmospheric glow discharge. This work is devoted to estimate the influence of CO2 and/or CO on reactivity in the Titan’s atmosphere. The exploration of planetary atmosphere is being advanced by the exciting results of the Cassin-Huygens mission to Saturn and Titan, its most famous moon. Most of the studies were mainly interested in the reactivity of the N2-CH4 gaseous mixture and with the primary products of reactions, but the atmosphere of Titan also contains oxygenated volatile species.  Keywords: Titan’s atmosphere, atmospheric glow discharge, FTIR spectroscopy 1 INTRODUCTION Atmospheric pressure glow discharges are of significant interest for a wide range of applica-tions such as pollution control, material pro-cessing or surface treatment. Among the many different types of  atmospheric pressure dis-charges the DC glow discharges is one of the most deeply studied [1, 2]. The gliding arc configuration has been shown to be a good mimic of planetary atmospheres [3] being used to replicate physical and chemical condi-tions in Titan. Titan is the largest moon in Saturn’s lunar system and the only one with a dense atmosphere-atmospheric pressure is ap-proximately1.5105 Pa [4-6]. It is the only lu-nar body with a substantial containing signifi-cant quantities of methane (CH4) and nitrogen (N2) in its atmosphere [7]. Chemical processes in Titan’s atmosphere are therefore able to create complex molecules containing C, N and H. This makes Titan our only planetary-scale laboratory for the synthesis of complex organ-ics molecules [8]. In Titan’s atmosphere, the dissociation of N2 and CH4 by solar ultraviolet radiation initiates chemical reactions that re-sult in the formation of complex organic mol-ecules.  The present work is focused on the experi-mental study of gaseous products produced in an atmospheric pressure glow discharge fed by N2-CH4 gas mixtures with CH4 concentrations in the range from 1 % to 4 % plus admixture of carbon dioxide (CO2) from 1% to 4 %. The gaseous products were analyzed by Fourier-Transform-Infra-Red spectroscopy (FTIR). 2 EXPERIMENTAL APPARATUS A simplified schematic drawing of the exper-imental set up is presented in Fig. 1. An at-mospheric pressure DC glow discharge was created between two stainless steel electrodes separated by a 2 mm gap. The electrodes sys-tem had standard configuration of the gliding arc discharge but due to low applied power and low gas velocity the discharge is not mov-ing along the electrodes. The discharge was formed in the stable abnormal glow regime with plasma channel of 1 mm in its diameter. The stainless steel vacuum chamber (volume of 1 litre) was evacuated by a rotary oil pump to maintain an oxygen free system. The dis-charge was operated with an applied power in range 4 to 15 W in pure nitrogen enriched by 1-4 % of CH4 with admixture of 1-3% of CO2 total flow rate of 200 sccm. The flow rates through the reactor for both methane and ni-trogen were regulated using MKS mass flow controllers. The exhaust gas was analyzed in-situ by FTIR spectroscopy.   Torokova L. et al.: The Influence of Admixtures on the Composition of Products by Nitrogen-Methane…   89  Fig.1: Schematic diagram of the experimental setup used for FTIR analysis of gaseous products of a DC glow discharge fed by various mixtures of N2-CH4-CO2. 3 RESULTS A typical FTIR spectrum revealing the prod-ucts formed in the nitrogen discharge fed by 2% of CH4 and 1% of CO2 is shown in Fig. 2.  Similar spectra were observed for other N2-CH4-CO2 molar ratios. The HITRAN spectral data individual absorption features was used for recognizing of specific compounds.  Hydrogen cyanide (HCN) was found to be the most abundant product at wavenumbers of 1430 cm-1 and of 720 cm-1. The other major products were ammonia (NH3) -966 cm-1 and acetylene (C2H2) -729 cm-1 as well as carbon monoxide (CO) and water. These products were recognized in all N2-CH4-CO2 gas mix-tures. The products concentrations are strongly depended on compositions of the gas mixture. Increasing the initial CH4 concentration from 2% to 4 % and also increasing admixture from 1% to 3% of CO2 lead to increase in the prod-ucts yield.     Fig.2: Sample spectrum of analysed products formed in a gas mixture 2 % of CH4 + 1 % of CO2 in N2.  Torokova L. et al.: The Influence of Admixtures on the Composition of Products by Nitrogen-Methane…   91   Fig.3: Concentration of hydrogen cyanide dependence on initial concentration of methane and also admixture of carbon dioxide. Fig. 3 shows the quantitative analysis of HCN at 1430 cm-1 formed under different experi-mental conditions. Since these experiments have been carried out for different CH4-N2 mixture ratios and the same gas flow rates, the evolution of different product concentrations was found to depend strongly on the initial gas ratios. The dependence of product concentra-tions is strongly dependent on the different CH4-N2 gas mixtures. On the other hand it was proofed [9] that the kinetics of HCN formation slows down in presence of CO, showing an inhibiting role of CO on HCN formation. In our experiments this influence was not recog-nize. 4 CONCLUSION The gaseous phase products formed in the atmospheric glow discharge fed by different mixtures of N2 plus CH4 (2 % and 4 %) and admixture of CO2 (1 and 3%) were determined by in situ FTIR analysis. The discharge was Torokova L. et al.: The Influence of Admixtures on the Composition of Products by Nitrogen-Methane…   92 operated in the flowing regime at different discharge currents at laboratory temperature. In situ FTIR technique for the exhaust gas phase sampling was successfully used for chemical analysis to deduce the gas composition in the N2-CH4-CO2 reactive gas mixture mimics of Titan’s atmosphere. Various nitrile compounds and hydrocarbons were observed in all experiments. HCN was identified as the major gas phase product in all of measurements. Others minor products detected were C2H2, NH3, CO2, CO and also some nitrile oxides. These results are consistent with the Titan’s atmospheric composition because the same compounds were detected during the Cassini-Huygens space mission. This fact clearly demonstrates that laboratory experiments can be used for prediction of both the presence and possible concentrations of compounds which have not been detected, yet. These simple organics should be tracers of the chemical groups constituting the dusty products. Acknowledgements This work has been supported by the EUROPLANET TNA2 and CEEPUS network AT-0063.  REFERENCES [1] Machala Z, Marode E, Laux C O, Kruger Ch, Journal of Advanced Oxidation Technologies 7 (2004) 133. [2] Kloc P, Wagner H E, Trunec D, Navratil Z, Fedoseev G, Journal of Physics D-Applied Physics 43 (2010) 34. [3] Torokova L, Watson J, Krcma F, Mazankova V, Mason N J, Horvath G, Matejcik S, Contributions to Plasma Physics 55 (2015) DOI 10.1002/ctpp.201400052 – in print. [4] Aplin K L, Surveys in Geophysics 27 (2006) 63. [5] Lavvas P, Yelle R V, Koskinen T, Bazin A, Vuitton V, Vigren E et al., Proceedings of the National Academy of Sciences of the United States of America 110 (2013) 2729. [6] Shebanits O, Wahlund J E, Mandt K, Agren K, Edberg N J T, Waite J H, Planetary and Space Science 84 (2013) 153. [7] Horst S M, Tolbert M A, Astrophysical Journal.  [8] Jagota S, Kawai J, Deamer D, McKay C, Khare B, Beeler D, Planetary and Space Science. 103 (2014) 167. [9] Fleury B, Carrasco N, Gautier T, Mahjoub A, He J, Szopa C, et al., Influence of CO on Titan atmospheric reactivity, Icarus, 2014 8//;238(0):221-9.   

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The Influence of Admixtures on the Composition of Products by Nitrogen-Methane Atmospheric Glow Discharge

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Kent Academic RepositoryFull text document (pdf)Copyright & reuseContent in the Kent Academic Repository is made available for research purposes. Unless otherwise stated allcontent is protected by copyright and in the absence of an open licence (eg Creative Commons), permissions for further reuse of content should be sought from the publisher, author or other copyright holder. Versions of researchThe version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record.EnquiriesFor any further enquiries regarding the licence status of this document, please contact: researchsupport@kent.ac.ukIf you believe this document infringes copyright then please contact the KAR admin team with the take-down information provided at http://kar.kent.ac.uk/contact.htmlCitation for published versionTorokova, L. and Mazankova, V. and Krcma, F. and Mason, Nigel and Matejcik, S.  (2015) Theinfluence of admixtures on the composition of products by nitrogen-methane atmospheric glowdischarge.    In:  Plasma Physics and Technology Journal.   2 (1).  pp. 88-91. Brno Universityof TechnologyDOILink to record in KARhttps://kar.kent.ac.uk/74691/Document VersionPublisher pdfTorokova L. et al.: The Influence of Admixtures on the Composition of Products by Nitrogen-Methane…  Plasma Physics and Technology 2015, 2, 1, 88-91 The Influence of Admixtures on the Composition of Products by Nitrogen-Methane Atmospheric Glow Discharge Torokova L.1,2, Mazankova V.1, Krcma F.1, Mason N.J.2, Matejcik S.3 1Faculty of Chemistry, Brno University of Technology, Purkynova 119, 612 00, Brno, Czech Republic 2Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA, UK 3Department of Experimental Physics, Comenius University, Mlynska dolina F-2, 842 48 Bratislava, Slovakia This work extends our experimentally studies with simulation of Titan’s atmosphere by atmospheric glow discharge. This work is devoted to estimate the influence of CO2 and/or CO on reactivity in the Titan’s atmosphere. The exploration of planetary atmosphere is being advanced by the exciting results of the Cassin-Huygens mission to Saturn and Titan, its most famous moon. Most of the studies were mainly interested in the reactivity of the N2-CH4 gaseous mixture and with the primary products of reactions, but the atmosphere of Titan also contains oxygenated volatile species.  Keywords: Titan’s atmosphere, atmospheric glow discharge, FTIR spectroscopy 1 INTRODUCTION Atmospheric pressure glow discharges are of significant interest for a wide range of applica-tions such as pollution control, material pro-cessing or surface treatment. Among the many different types of  atmospheric pressure dis-charges the DC glow discharges is one of the most deeply studied [1, 2]. The gliding arc configuration has been shown to be a good mimic of planetary atmospheres [3] being used to replicate physical and chemical condi-tions in Titan. Titan is the largest moon in Saturn’s lunar system and the only one with a dense atmosphere-atmospheric pressure is ap-proximately1.5105 Pa [4-6]. It is the only lu-nar body with a substantial containing signifi-cant quantities of methane (CH4) and nitrogen (N2) in its atmosphere [7]. Chemical processes in Titan’s atmosphere are therefore able to create complex molecules containing C, N and H. This makes Titan our only planetary-scale laboratory for the synthesis of complex organ-ics molecules [8]. In Titan’s atmosphere, the dissociation of N2 and CH4 by solar ultraviolet radiation initiates chemical reactions that re-sult in the formation of complex organic mol-ecules.  The present work is focused on the experi-mental study of gaseous products produced in an atmospheric pressure glow discharge fed by N2-CH4 gas mixtures with CH4 concentrations in the range from 1 % to 4 % plus admixture of carbon dioxide (CO2) from 1% to 4 %. The gaseous products were analyzed by Fourier-Transform-Infra-Red spectroscopy (FTIR). 2 EXPERIMENTAL APPARATUS A simplified schematic drawing of the exper-imental set up is presented in Fig. 1. An at-mospheric pressure DC glow discharge was created between two stainless steel electrodes separated by a 2 mm gap. The electrodes sys-tem had standard configuration of the gliding arc discharge but due to low applied power and low gas velocity the discharge is not mov-ing along the electrodes. The discharge was formed in the stable abnormal glow regime with plasma channel of 1 mm in its diameter. The stainless steel vacuum chamber (volume of 1 litre) was evacuated by a rotary oil pump to maintain an oxygen free system. The dis-charge was operated with an applied power in range 4 to 15 W in pure nitrogen enriched by 1-4 % of CH4 with admixture of 1-3% of CO2 total flow rate of 200 sccm. The flow rates through the reactor for both methane and ni-trogen were regulated using MKS mass flow controllers. The exhaust gas was analyzed in-situ by FTIR spectroscopy.   Torokova L. et al.: The Influence of Admixtures on the Composition of Products by Nitrogen-Methane…   89  Fig.1: Schematic diagram of the experimental setup used for FTIR analysis of gaseous products of a DC glow discharge fed by various mixtures of N2-CH4-CO2. 3 RESULTS A typical FTIR spectrum revealing the prod-ucts formed in the nitrogen discharge fed by 2% of CH4 and 1% of CO2 is shown in Fig. 2.  Similar spectra were observed for other N2-CH4-CO2 molar ratios. The HITRAN spectral data individual absorption features was used for recognizing of specific compounds.  Hydrogen cyanide (HCN) was found to be the most abundant product at wavenumbers of 1430 cm-1 and of 720 cm-1. The other major products were ammonia (NH3) -966 cm-1 and acetylene (C2H2) -729 cm-1 as well as carbon monoxide (CO) and water. These products were recognized in all N2-CH4-CO2 gas mix-tures. The products concentrations are strongly depended on compositions of the gas mixture. Increasing the initial CH4 concentration from 2% to 4 % and also increasing admixture from 1% to 3% of CO2 lead to increase in the prod-ucts yield.     Fig.2: Sample spectrum of analysed products formed in a gas mixture 2 % of CH4 + 1 % of CO2 in N2.  Torokova L. et al.: The Influence of Admixtures on the Composition of Products by Nitrogen-Methane…   91   Fig.3: Concentration of hydrogen cyanide dependence on initial concentration of methane and also admixture of carbon dioxide. Fig. 3 shows the quantitative analysis of HCN at 1430 cm-1 formed under different experi-mental conditions. Since these experiments have been carried out for different CH4-N2 mixture ratios and the same gas flow rates, the evolution of different product concentrations was found to depend strongly on the initial gas ratios. The dependence of product concentra-tions is strongly dependent on the different CH4-N2 gas mixtures. On the other hand it was proofed [9] that the kinetics of HCN formation slows down in presence of CO, showing an inhibiting role of CO on HCN formation. In our experiments this influence was not recog-nize. 4 CONCLUSION The gaseous phase products formed in the atmospheric glow discharge fed by different mixtures of N2 plus CH4 (2 % and 4 %) and admixture of CO2 (1 and 3%) were determined by in situ FTIR analysis. The discharge was Torokova L. et al.: The Influence of Admixtures on the Composition of Products by Nitrogen-Methane…   92 operated in the flowing regime at different discharge currents at laboratory temperature. In situ FTIR technique for the exhaust gas phase sampling was successfully used for chemical analysis to deduce the gas composition in the N2-CH4-CO2 reactive gas mixture mimics of Titan’s atmosphere. Various nitrile compounds and hydrocarbons were observed in all experiments. HCN was identified as the major gas phase product in all of measurements. Others minor products detected were C2H2, NH3, CO2, CO and also some nitrile oxides. These results are consistent with the Titan’s atmospheric composition because the same compounds were detected during the Cassini-Huygens space mission. This fact clearly demonstrates that laboratory experiments can be used for prediction of both the presence and possible concentrations of compounds which have not been detected, yet. These simple organics should be tracers of the chemical groups constituting the dusty products. Acknowledgements This work has been supported by the EUROPLANET TNA2 and CEEPUS network AT-0063.  REFERENCES [1] Machala Z, Marode E, Laux C O, Kruger Ch, Journal of Advanced Oxidation Technologies 7 (2004) 133. [2] Kloc P, Wagner H E, Trunec D, Navratil Z, Fedoseev G, Journal of Physics D-Applied Physics 43 (2010) 34. [3] Torokova L, Watson J, Krcma F, Mazankova V, Mason N J, Horvath G, Matejcik S, Contributions to Plasma Physics 55 (2015) DOI 10.1002/ctpp.201400052 – in print. [4] Aplin K L, Surveys in Geophysics 27 (2006) 63. [5] Lavvas P, Yelle R V, Koskinen T, Bazin A, Vuitton V, Vigren E et al., Proceedings of the National Academy of Sciences of the United States of America 110 (2013) 2729. [6] Shebanits O, Wahlund J E, Mandt K, Agren K, Edberg N J T, Waite J H, Planetary and Space Science 84 (2013) 153. [7] Horst S M, Tolbert M A, Astrophysical Journal.  [8] Jagota S, Kawai J, Deamer D, McKay C, Khare B, Beeler D, Planetary and Space Science. 103 (2014) 167. [9] Fleury B, Carrasco N, Gautier T, Mahjoub A, He J, Szopa C, et al., Influence of CO on Titan atmospheric reactivity, Icarus, 2014 8//;238(0):221-9.   

The influence of admixtures on the composition of products by nitrogen-methane atmospheric glow discharge

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The influence of admixtures on the composition of products by nitrogen-methane atmospheric glow discharge

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