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Farzaneh, A., DeJaco, R. F., Ohlin, L., Holmgren, A., Siepmann, J. I. & Grahn, M. (2017). Comparative Study of the Effect of Defects on Selective Adsorption of Butanol from Butanol/Water Binary Vapor Mixtures in Silicalite-1 Films. Langmuir, 33(34), 8420-8427
Open this publication in new window or tab >>Comparative Study of the Effect of Defects on Selective Adsorption of Butanol from Butanol/Water Binary Vapor Mixtures in Silicalite-1 Films
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2017 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, no 34, p. 8420-8427Article in journal (Refereed) Published
Abstract [en]

A promising route for sustainable 1-butanol (butanol) production is ABE (acetone, butanol, ethanol) fermentation. However, recovery of the products is challenging because of the low concentrations obtained in the aqueous solution, thus hampering large-scale production of biobutanol. Membrane and adsorbent-based technologies using hydrophobic zeolites are interesting alternatives to traditional separation techniques (e.g., distillation) for energy-efficient separation of butanol from aqueous mixtures. To maximize the butanol over water selectivity of the material, it is important to reduce the number of hydrophilic adsorption sites. This can, for instance, be achieved by reducing the density of lattice defect sites where polar silanol groups are found. The density of silanol defects can be reduced by preparing the zeolite at neutral pH instead of using traditional synthesis solutions with high pH. In this work, binary adsorption of butanol and water in two silicalite-1 films was studied using in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy under equal experimental conditions. One of the films was prepared in fluoride medium, whereas the other one was prepared at high pH using traditional synthesis conditions. The amounts of water and butanol adsorbed from binary vapor mixtures of varying composition were determined at 35 and 50 °C, and the corresponding adsorption selectivities were also obtained. Both samples showed very high selectivities (100-23 000) toward butanol under the conditions studied. The sample having low density of defects, in general, showed ca. a factor 10 times higher butanol selectivity than the sample having a higher density of defects at the same experimental conditions. This difference was due to a much lower adsorption of water in the sample with low density of internal defects. Analysis of molecular simulation trajectories provides insights on the local selectivities in the zeolite channel network and at the film surface.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-65148 (URN)10.1021/acs.langmuir.7b02097 (DOI)000409292500008 ()28767246 (PubMedID)2-s2.0-85028620796 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-09-05 (rokbeg)

Available from: 2017-08-17 Created: 2017-08-17 Last updated: 2018-07-10Bibliographically approved
Ohlin, L., Farzaneh, A., Holmgren, A., Hedlund, J. & Grahn, M. (2017). Ternary Adsorption of Methane, Water and Carbon Dioxide in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy. The Journal of Physical Chemistry C, 121(27), 14703-14711
Open this publication in new window or tab >>Ternary Adsorption of Methane, Water and Carbon Dioxide in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy
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2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 27, p. 14703-14711Article in journal (Refereed) Published
Abstract [en]

The main component in biogas and natural gas is methane but these gases also contain water and carbon dioxide that often have to be removed in order to increase the calorific value of the gas. Membrane and adsorbent-based technologies using zeolites are interesting alternatives for efficient separation of these components. To develop efficient processes, it is essential to know the adsorption properties of the zeolite. In the present work, adsorption of methane, carbon dioxide and water from ternary mixtures in high silica zeolite Na-ZSM-5 was studied using in-situ ATR (Attenuated Total Reflection) – FTIR (Fourier Transform Infrared) spectroscopy. Adsorbed concentrations were extracted from the infrared spectra and the obtained loadings were compared to values predicted by the Ideal Adsorbed Solution Theory (IAST). The IAST could not fully capture the adsorption behavior of this ternary mixture, indicating that the adsorbed phase is not behaving as an ideal mixture. The CO2/CH4 adsorption selectivities determined for the ternary mixtures were compared to selectivities determined for binary mixtures in our previous work, indicating that the presence of water slightly improves the CO2/CH4 adsorption selectivity at lower temperatures. Further, the results show that water and carbon dioxide are adsorbed preferentially over methane in high silica zeolite Na-ZSM-5.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-64397 (URN)10.1021/acs.jpcc.7b04405 (DOI)000405761600035 ()2-s2.0-85024101175 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-08-08 (rokbeg)

Available from: 2017-06-22 Created: 2017-06-22 Last updated: 2018-05-28Bibliographically approved
Ohlin, L., Berezovsky, V., Öberg, S., Farzaneh, A., Holmgren, A. & Grahn, M. (2016). Effect of Water on the Adsorption of Methane and Carbon Dioxide in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy. The Journal of Physical Chemistry C, 120(51), 29144-29152
Open this publication in new window or tab >>Effect of Water on the Adsorption of Methane and Carbon Dioxide in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy
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2016 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 51, p. 29144-29152Article in journal (Refereed) Published
Abstract [en]

Methane is the main component in biogas and natural gas along with contaminants such as water and carbon dioxide. Separation of methane from these contaminants is therefore an important step in the upgrading process. Zeolite adsorbents and zeolite membranes have great potential to be cost-efficient candidates for upgrading biogas and natural gas, and in both of these applications, knowing the nature of the competitive adsorption is of great importance to further develop the properties of the zeolite materials. The binary adsorption of methane and carbon dioxide in zeolites has been studied to some extent, but the influence of water has been much less studied. In the present work, in situ ATR (attenuated total reflection)–FTIR (Fourier transform infrared) spectroscopy was used to study the adsorption of water/methane and water/carbon dioxide from binary mixtures in a high-silica Na-ZSM-5 zeolite film at various gas compositions and temperatures. Adsorbed concentrations for all species were determined from the recorded IR spectra, and the experimental values were compared to values predicted using the ideal adsorbed solution theory (IAST). At lower temperatures (35, 50, and 85 °C), the IAST was able to predict the binary adsorption of water and methane, whereas the values predicted by the IAST deviated from the experimental data at the highest temperature (120 °C). For the binary adsorption of water and carbon dioxide, the IAST could not predict the adsorption values accurately. This discrepancy was assigned to the particular adsorption behavior of water in high-silica MFI forming clusters at hydrophilic sites. However, the predicted values did follow the same trend as the experimental values. The adsorption selectivity was determined, and it was found that the H2O/CH4 adsorption selectivity was decreasing with increasing water content in the gas phase at low temperatures whereas the selectivity was increasing at higher temperatures. The H2O/CO2 adsorption selectivity was increasing with increasing water content at all temperatures.

National Category
Chemical Process Engineering Other Physics Topics
Research subject
Chemical Technology; Applied Physics
Identifiers
urn:nbn:se:ltu:diva-61272 (URN)10.1021/acs.jpcc.6b09224 (DOI)000391160400028 ()2-s2.0-85008428222 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-01-11 (rokbeg)

Available from: 2016-12-27 Created: 2016-12-27 Last updated: 2018-07-10Bibliographically approved
Farzaneh, A., Zhou, M., Potapova, E., Bacsik, Z., Ohlin, L., Holmgren, A., . . . Grahn, M. (2015). Adsorption of Water and Butanol in Silicalite-1 Film Studied with in-situ ATR-FTIR Spectroscopy (ed.). Paper presented at . Langmuir, 31(17), 4887-4894
Open this publication in new window or tab >>Adsorption of Water and Butanol in Silicalite-1 Film Studied with in-situ ATR-FTIR Spectroscopy
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2015 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 17, p. 4887-4894Article in journal (Refereed) Published
Abstract [en]

Biobutanol produced by, e.g., acetone–butanol–ethanol (ABE) fermentation is a promising alternative to petroleum-based chemicals as, e.g., solvent and fuel. Recovery of butanol from dilute fermentation broths by hydrophobic membranes and adsorbents has been identified as a promising route. In this work, the adsorption of water and butanol vapor in a silicalite-1 film was studied using in situ attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy to better understand the adsorption properties of silicalite-1 membranes and adsorbents. Single-component adsorption isotherms were determined in the temperature range of 35–120 °C, and the Langmuir model was successfully fitted to the experimental data. The adsorption of butanol is very favorable compared to that of water. When the silicalite-1 film was exposed to a butanol/water vapor mixture with 15 mol % butanol (which is the vapor composition of an aqueous solution containing 2 wt % butanol, a typical concentration in an ABE fermentation broth, i.e., the composition of the gas obtained from gas stripping of an ABE broth) at 35 °C, the adsorption selectivity toward butanol was as high as 107. These results confirm that silicalite-1 quite selectively adsorbs hydrocarbons from vapor mixtures. To the best of our knowledge, this is the first comprehensive study on the adsorption of water and butanol in silicalite-1 from vapor phase.

Abstract [sv]

Bio-butanol produced by e.g. acetone–butanol–ethanol (ABE) fermentation is a promising alternative to petroleum-based chemicals as e.g. solvent and fuel. Recovery of butanol from dilute fermentation broths by hydrophobic membranes and adsorbents has been identified as a promising route. In this work, the adsorption of water and butanol vapor in a silicalite-1 film was studied using in-situ ATR-FTIR spectroscopy in order to better understand the adsorption properties of silicalite-1 membranes and adsorbents. Single component adsorption isotherms were determined in the temperature range of 35-120°C and the Langmuir model was successfully fitted to the experimental data. The adsorption of butanol is very favorable compared to that of water. When the silicalite-1 film was exposed to a butanol/water vapor mixture with 15 mol% of butanol (which is the vapor composition of an aqueous solution containing 2 wt% of butanol, a typical concentration in an ABE fermentation broth, i.e. the composition of the gas obtained from gas stripping of an ABE broth) at 35 °C, the adsorption selectivity towards butanol was as high as 107. These results confirm that silicalite-1 quite selectively adsorbs hydrocarbons from vapor mixtures.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-11363 (URN)10.1021/acs.langmuir.5b00489 (DOI)000354154100010 ()25871262 (PubMedID)2-s2.0-84928975335 (Scopus ID)a506afed-96a6-4841-b99b-143794fb680d (Local ID)a506afed-96a6-4841-b99b-143794fb680d (Archive number)a506afed-96a6-4841-b99b-143794fb680d (OAI)
Note
Validerad; 2015; Nivå 2; 20150420 (magr)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ohlin, L. (2015). An in-situ ATR-FTIR Spectroscopy Study of Adsorption in MFI Zeolites: A step towards effective upgrading of biofuels (ed.). (Doctoral dissertation). Paper presented at . : Luleå tekniska universitet
Open this publication in new window or tab >>An in-situ ATR-FTIR Spectroscopy Study of Adsorption in MFI Zeolites: A step towards effective upgrading of biofuels
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Global warming is believed to be caused by the extensive emission of greenhouse gases, for example carbon dioxide, into the atmosphere by combustion of fossil fuels, such as coal, oil and natural gas. To reduce the emission of carbon dioxide and hence avoid global warming, alternative fuels derived from renewable resources are desired. Another reason for the worldwide interest in finding alternative fuels is that the reserves of the fossil fuels are limited and the oil and gas sources will eventually run out. Biogas and biobutanol are renewable biofuels which are interesting alternatives to fossil fuels. Biogas is produced during degradation of organic material forming a mixture of mainly methane and carbon dioxide with water as a common trace component. Biobutanol is produced from ABE (acetone, butanol and ethanol) fermentation of biomass. Purification of biogas and biobutanol is essential to increase the heat value of the fuels. Traditional purification processes are energy demanding and expensive. Therefore, other separation processes are currently sought for. Zeolites are promising alternatives due to their great potential both as selective adsorbents and as membranes. Due to the unique pore structure, zeolites are capable of separating components based on their adsorption properties. In the present work, single component adsorption of biogas components such as methane, carbon dioxide and water in zeolite ZSM-5 was studied as well as adsorption of water and butanol in silicalite-1 using in-situ ATR-FTIR spectroscopy. The method was successfully further used to study multicomponent adsorption. For single gas adsorption experiments, recorded infrared spectra of adsorbed methane, carbon dioxide and water showed characteristic, well separated, bands for each gas. Adsorbed concentrations were determined from the recorded infrared spectra. The Langmuir model was fitted to the adsorption isotherms and the model matched the experimental data very well. The fitted Langmuir parameters obtained in the present work was in agreement with values reported in the literature. For multicomponent adsorption experiments, the Ideal Adsorbed Solution Theory (IAST) was used to predict the adsorbed concentrations of methane, carbon dioxide and water using the single component adsorption isotherm parameters as input. In general, the IAST was shown to be a fairly good model for predicting the adsorbed concentrations of methane and carbon dioxide from binary mixtures. For the amount of adsorbed methane from mixtures including water, the IAST predicted the values fairly well. However, for mixtures containing water and carbon dioxide, the IAST could not fully describe the adsorption behavior of the two components. The CO2/CH4 adsorption selectivity was determined for various gas compositions and temperatures showing a general increase in the selectivity with decreasing temperature. This indicates that the separation of carbon dioxide from biogas should be more efficient at lower temperatures. Compared to the literature, the selectivity observed in the present work is relatively high indicating that Na-ZSM-5 may be an effective membrane material for upgrading biogas. Moreover, butanol was preferentially adsorbed over water in silicalite-1, indicating that silicalite-1 may be a promising material for recovery of butanol from dilute water solutions.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2015
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-16809 (URN)02488613-953a-4162-95bd-4660c7f2c8bd (Local ID)978-91-7583-318-7 (ISBN)978-91-7583-319-4 (ISBN)02488613-953a-4162-95bd-4660c7f2c8bd (Archive number)02488613-953a-4162-95bd-4660c7f2c8bd (OAI)
Note
Godkänd; 2015; 20150325 (linohl); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Lindsay Ohlin Ämne: Kemisk Teknologi /Chemical Technology Avhandling: An in-situ ATR-FTIR Spectroscopy Study of Adsorption in MFI Zeolites Opponent: Professor Niklas Hedin, Avd för materialkemi, Stockholms universitet, Stockholm Ordförande: Biträdande professor Mattias Grahn, Avd för kemiteknik, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet, Luleå Tid: Fredag 29 maj kl 10.15 Plats: C305, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-05-28Bibliographically approved
Ohlin, L. & Grahn, M. (2014). Detailed Investigation of the Binary Adsorption of Carbon Dioxide and Methane in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy (ed.). Paper presented at . The Journal of Physical Chemistry C, 118(12), 6207-6213
Open this publication in new window or tab >>Detailed Investigation of the Binary Adsorption of Carbon Dioxide and Methane in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy
2014 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 12, p. 6207-6213Article in journal (Refereed) Published
Abstract [en]

The separation of carbon dioxide from methane is an important process when purifying biogas and natural gas. Zeolite membranes and adsorbents are among the technologies suggested for efficient separation of carbon dioxide from these gases. In the present work, the adsorption of carbon dioxide and methane from binary mixtures in a low alumina Na-ZSM-5 zeolite film at various gas compositions and temperatures was studied using in situ ATR-FTIR (attenuated total reflection Fourier transform infrared) spectroscopy. Adsorbed concentrations were successfully extracted from infrared spectra. The experimental values of the adsorbed phase mole fraction of carbon dioxide and methane were compared to values predicted using the ideal adsorbed solution theory (IAST). The values predicted with the IAST agreed very well with values determined experimentally. The CO2/CH4 adsorption selectivity was determined, and at 35 °C a selectivity of 15.4 was obtained for an equimolar gas mixture. At the highest (0.9) and lowest (0.03) investigated mole fractions of carbon dioxide in the gas phase, the selectivity was higher compared to the other investigated mole fractions. At 35 °C the highest observed selectivity values were 31.1 and 20.4 for the highest and the lowest adsorbed mole fraction, respectively. At compositions closest to those found in biogas and natural gas, there was a decrease in the selectivity at higher temperatures, indicating that separation of carbon dioxide from methane in biogas and natural gas may be more efficient at low temperatures

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-12075 (URN)10.1021/jp4110097 (DOI)000333578300025 ()2-s2.0-84897471611 (Scopus ID)b20eb16e-f742-498e-b8f3-f599daf1d8ef (Local ID)b20eb16e-f742-498e-b8f3-f599daf1d8ef (Archive number)b20eb16e-f742-498e-b8f3-f599daf1d8ef (OAI)
Note
Validerad; 2014; 20140402 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Faisal, A., Zarebska, A., Saremi, P., Korelskiy, D., Ohlin, L., Rova, U., . . . Grahn, M. (2014). MFI zeolite as adsorbent for selective recovery of hydrocarbons from ABE fermentation broths (ed.). Paper presented at . Adsorption, 20(2-3), 465-470
Open this publication in new window or tab >>MFI zeolite as adsorbent for selective recovery of hydrocarbons from ABE fermentation broths
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2014 (English)In: Adsorption, ISSN 0929-5607, E-ISSN 1572-8757, Vol. 20, no 2-3, p. 465-470Article in journal (Refereed) Published
Abstract [en]

1-Butanol and butyric acid are two interesting compounds that may be produced by acetone, butanol, and ethanol fermentation using e.g. Clostridium acetobutylicum. The main drawback, restricting the commercialization potential of this process, is the toxicity of butanol for the cell culture resulting in low concentrations of this compound in the broth. To make this process economically viable, an efficient recovery process has to be developed. In this work, a hydrophobic MFI type zeolite with high silica to alumina ratio was evaluated as adsorbent for the recovery of butanol and butyric acid from model solutions. Dual component adsorption experiments revealed that both butanol and butyric acid showed a high affinity for the hydrophobic MFI zeolite when adsorbed from aqueous model solutions. Multicomponent adsorption experiments using model solutions, mimicking real fermentation broths, revealed that the adsorbent was very selective to the target compounds. Further, the adsorption of butyric and acetic acid was found to be pH dependent with high adsorption below, and low adsorption above, the respective pKa values of the acids. Thermal desorption of butanol from MFI type zeolite was also studied and a suitable desorption temperature was identified.

National Category
Chemical Process Engineering Bioprocess Technology
Research subject
Chemical Technology; Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-4194 (URN)10.1007/s10450-013-9576-6 (DOI)000331971600026 ()2-s2.0-84896900141 (Scopus ID)219f81ce-cf91-4675-ab58-fdd5b675d8f7 (Local ID)219f81ce-cf91-4675-ab58-fdd5b675d8f7 (Archive number)219f81ce-cf91-4675-ab58-fdd5b675d8f7 (OAI)
Note
Validerad; 2014; 20130920 (dankor)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ohlin, L., Bazin, P., Thibault-Starzyk, F., Hedlund, J. & Grahn, M. (2013). Adsorption of CO2, CH4, and H2O in zeolite ZSM-5 studied using in situ ATR-FTIR spectroscopy (ed.). Paper presented at . The Journal of Physical Chemistry C, 117(33)
Open this publication in new window or tab >>Adsorption of CO2, CH4, and H2O in zeolite ZSM-5 studied using in situ ATR-FTIR spectroscopy
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2013 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 33Article in journal (Refereed) Published
Abstract [en]

Biogas and natural gas are interesting fuels with high H/C ratio. However, these gases frequently contain carbon dioxide and water which lowers the heat value of the gas and may induce corrosion. Therefore, the development of more efficient processes, such as membrane processes and improved adsorbents, for the separation of carbon dioxide and water from biogas and natural gas is of great importance. Zeolite ZSM-5 membranes are promising for this separation which is controlled by the adsorption and diffusion of the different species in the zeolite. Multicomponent adsorption data are therefore required for development of new membrane and adsorption processes. In the present work, the adsorption of water, carbon dioxide, and methane in a Na-ZSM-5 zeolite film at various temperatures was studied by in situ Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy for the first time. Adsorption isotherms were retrieved from the experimental data and the Langmuir model fitted the isotherms very well. Limiting heat of adsorption was determined from the Henrýs law regime and the values determined agreed well with previously reported data. A few experiments were conducted with multicomponent mixtures and the experimentally determined amounts adsorbed were compared with values predicted by the Ideal Adsorbed Solution Theory (IAST). It was found that for the binary mixture of carbon dioxide and methane there was good agreement between the experimental values and those predicted by the IAST. However, when water was also introduced, the IAST could not fully capture the adsorption behavior of the multicomponent mixture, probably because the adsorbed phase is not ideal. These findings are in line with previous reports for adsorption in zeolites. The multicomponent adsorption behavior of this system will be further investigated in forthcoming work.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-7448 (URN)10.1021/jp4037183 (DOI)000323593100025 ()5d409293-eb1a-47d1-91ec-4a4b3e790ced (Local ID)5d409293-eb1a-47d1-91ec-4a4b3e790ced (Archive number)5d409293-eb1a-47d1-91ec-4a4b3e790ced (OAI)
Note
Validerad; 2013; 20130913 (magr)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ohlin, L. (2013). Adsorption of water, carbon dioxide and methane in zeolite ZSM-5 studied using in-situ ATR-FTIR spectroscopy (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Adsorption of water, carbon dioxide and methane in zeolite ZSM-5 studied using in-situ ATR-FTIR spectroscopy
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Global warming is believed to be caused by the extensive emission of greenhouse gases, such as carbon dioxide, into the atmosphere by combustion of fossil fuels, such as coal, oil and natural gas.To reduce the emission of carbon dioxide and hence avoid global warming, alternative fuels derived from renewable resources are desired. Another reason for the worldwide interest in finding alternative fuels is that the reserves of the fossile fuels are limited and the oil and gas resources will eventually run out.Biogas and natural gas are interesting alternatives with no or at least reduced emission of fossil carbon dioxide to the atmosphere as compared to coal and oil. Both gases mainly consist of methane (60–95%) but may also contain a large fraction of carbon dioxide and water. Removal of carbon dioxide and water from biogas and natural gas is of great importance mainly to lower the transportation costs and to increase the heat value of the gas. The most commonly used separation technique is amine absorption. This is an expensive and complex process and alternative techniques are desired. Zeolites are an interesting alternative due to their great potential both as selective adsorbents and membranes. Due to the unique pore structure zeolites are capable of separating species in a mixture based on the molecule size and adsorption properties. Since water, carbon dioxide and methane all have a molecular size smaller than the pore size of the zeolite ZSM-5 studied in the present work, the molecules can enter and adsorb in the pores and hence the separation is based on adsorption rather than size.In the present work, the single component adsorption of water, carbon dioxide and methane in zeolite ZSM-5 was studied using in-situ Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and the method was successfully further used to study multicomponent adsorption in zeolites.For single gas adsorption experiments, recorded infrared spectra of adsorbed water, carbon dioxide and methane showed characteristic well separated bands for each gas. Adsorbed concentrations of water, carbon dioxide and methane were determined from the recorded infrared spectra. For single gas experiments, the Langmuir model was fitted to the adsorption isotherms and the model matched the experimental data very well. The fitted Langmuir parameters obtained in the present work showed good agreement with values reported in the literature.For multicomponent adsorption experiments, the Ideal Adsorbed Solution Theory (IAST) was used to predict the adsorbed concentrations of water, carbon dioxide and methane using the single component adsorption isotherm parameters as input. The IAST accurately predicted the adsorbed concentrations of both carbon dioxide and methane when adsorbed from binary mixtures. Internary mixtures, also including water, the IAST accurately predicted the adsorbed concentration of methane, however it severely underestimated the adsorbed concentration of carbon dioxide.The latter is probably an effect of a non-ideal behavior of carbon dioxide in the presence of water.The CO2/CH4 adsorption selectivity was determined for various gas compositions and temperatures showing a general increase in the selectivity with decreasing temperature, which is related to the higher heat of adsorption of carbon dioxide. This indicates that the separation of carbon dioxide from biogas and natural gas should be more efficient at lower temperatures. Compared to the literature, the selectivity observed in the present work is relatively high indicating that low silica Na-ZSN-5 may be an effective membrane material.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2013
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-17956 (URN)60979b0a-e4b9-43e9-84e9-f08c557e3f08 (Local ID)978-91-7439-576-1 (ISBN)978-91-7439-577-8 (ISBN)60979b0a-e4b9-43e9-84e9-f08c557e3f08 (Archive number)60979b0a-e4b9-43e9-84e9-f08c557e3f08 (OAI)
Note
Godkänd; 2013; 20130308 (andbra); Tillkännagivande licentiatseminarium 2013-04-04 Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Lindsay Ohlin Ämne: Kemisk teknologi/Chemical Technology Uppsats: Adsorption of Water, Carbon Dioxide and Methane in Zeolite ZSM-5 Studied Using in-situ ATR-FTIR Spectroscopy Examinator: Bitr professor Mattias Grahn, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Researcher Zoltán Bacsik, Institutionen för material- och miljökemi, Stockholms universitet Tid: Fredag den 26 april 2013 kl 10.30 Plats: F531, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-05-28Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1404-9505

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