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Publications (10 of 15) Show all publications
Grahn, M., Faisal, A., Öhrman, O. G. ., Zhou, M., Signorile, M., Crocellà, V., . . . Hedlund, J. (2019). Small ZSM-5 crystals with low defect density as an effective catalyst for conversion of methanol to hydrocarbons. Catalysis Today
Open this publication in new window or tab >>Small ZSM-5 crystals with low defect density as an effective catalyst for conversion of methanol to hydrocarbons
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2019 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308Article in journal (Refereed) Epub ahead of print
Abstract [en]

This work presents the synthesis of nearly defect-free ZSM-5 nanosized crystals, prepared in fluoride medium by seeding with silicalite-1. This material was carefully characterized and its catalytic performances in the methanol to hydrocarbons (MTH) reaction were assessed. Such fluoride-based material was compared to a reference ZSM-5, produced through a conventional alkaline synthesis but from the same seeding. Despite both the materials show closely identical morphology and they have a comparable acid site population, the catalyst prepared using the fluoride route showed significantly longer lifetime in MTH compared to the catalyst prepared using conventional synthesis at high pH. The slower deactivation for the samples prepared using the fluoride route was ascribed, thanks to a thorough in situ IR spectroscopy study, to its lower density of internal defects. According to the UV-Raman characterization of coke on the spent catalyst, the fluoride-based ZSM-5 catalyst produces less molecular coke species, most probably because of the absence of enlarged cavities/channels as due to the presence of internal defects. On the basis of these observations, the deactivation mechanism in the ZSM-5 synthesized by fluoride medium could be mostly related to the deposition of an external layer of bulk coke, whereas in the alkali-synthesized catalyst an additional effect from molecular coke accumulating within the porous network accelerates the deactivation process.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
ZSM-5, defects, hydrocarbons, deactivation, MTH, IR spectroscopy, OH groups
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-76102 (URN)10.1016/j.cattod.2019.09.023 (DOI)2-s2.0-85073006485 (Scopus ID)
Available from: 2019-09-24 Created: 2019-09-24 Last updated: 2019-10-21
Nabavi, M. S., Zhou, M., Mouzon, J., Grahn, M. & Hedlund, J. (2019). Stability of colloidal ZSM-5 catalysts synthesized in fluoride and hydroxide media. Microporous and Mesoporous Materials, 278, 167-174
Open this publication in new window or tab >>Stability of colloidal ZSM-5 catalysts synthesized in fluoride and hydroxide media
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2019 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 278, p. 167-174Article in journal (Refereed) Published
Abstract [en]

ZSM-5 zeolite crystals with carefully controlled thicknesses in the range 20–110 nm, i.e. in the colloidal domain, were synthesized in fluoride and hydroxide media. The crystals were treated in steam at high temperature to evaluate the stability and evaluated by SEM, XRD, NMR and NH3-TPD. The results showed that the framework of crystals synthesized in fluoride media was more stable than the framework of crystals synthesized in hydroxide media. This should be an effect of lower concentration of structural defects and silanol groups in the former zeolites as reported by other groups. However, independently of the synthesis conditions, all crystals dealuminated rapidly when treated with steam at the conditions investigated in the present work.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
ZSM-5, Catalyst, Stability, Framework, Steam, Dealumination
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-71897 (URN)10.1016/j.micromeso.2018.11.007 (DOI)000459841900020 ()2-s2.0-85057248871 (Scopus ID)
Note

Validerad;2019;Nivå 2;2018-12-05 (svasva)

Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2019-04-12Bibliographically approved
Zhou, M. & Hedlund, J. (2018). Facile Preparation of Hydrophobic Colloidal MFI and CHA Crystals and Oriented Ultra-thin Films. Angewandte Chemie International Edition, 130(34), 11132-11136
Open this publication in new window or tab >>Facile Preparation of Hydrophobic Colloidal MFI and CHA Crystals and Oriented Ultra-thin Films
2018 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 130, no 34, p. 11132-11136Article in journal (Refereed) Published
Abstract [en]

We report novel routes for synthesis of defect-free, hydrophobic and monodispersed 10 nm (5 unit cells) thick MFI crystals and 100 nm CHA crystals. The crystals are obtained in high yield and display very high 1-butanol adsorption from aqueous solution. These crystals are assembled in monolayers for the growth of ultra-thin and uniformly oriented films with thicknesses of 36 nm and 330 nm, respectively, using a synthesis gel in the form of a powder. This method is very simple and may open up for industrial preparation of materials with improved performances.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-70084 (URN)10.1002/anie.201806502 (DOI)000442863700029 ()29969534 (PubMedID)
Note

Validerad;2018;Nivå 2;2018-08-14 (andbra)

Available from: 2018-07-06 Created: 2018-07-06 Last updated: 2018-09-10Bibliographically approved
Korelskiy, D., Grahn, M., Ye, P., Zhou, M. & Hedlund, J. (2016). A study of CO2/CO separation by sub-micron b-oriented MFI membranes (ed.). Paper presented at . RSC Advances, 6(70), 65475-65482
Open this publication in new window or tab >>A study of CO2/CO separation by sub-micron b-oriented MFI membranes
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2016 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 70, p. 65475-65482Article in journal (Refereed) Published
Abstract [en]

Separation of CO2 and CO is of great importance for many industrial applications. Today, CO2 is removed from CO mainly by adsorption or physical or chemical absorption systems that are energy-intensive and expensive. Membranes are listed among the most promising sustainable and energy-efficient alternatives for CO2 separation. Here, we study CO2/CO separation by novel sub-micron b-oriented MFI zeolite membranes in a temperature range of 258-303 K and at a feed pressure of 9 bar. Under all experimental conditions studied, the membranes were CO2-selective and displayed high CO2 permeance ranging from 17 000 to 23 000 gpu. With decreasing temperature, the CO2/CO selectivity was increasing, reaching a maximum of 26 at 258 K. We also developed a mathematical model to describe the membrane process, and it indicated that the membrane separation performance was a result of selective adsorption of CO2 on the polar zeolite. The heat of adsorption of CO2 on the zeolite is more negative due to the high quadrupole moment and polarisability of the molecule as compared to CO. At the same time, diffusional coupling (correlation effects) at high adsorbed loadings was found to favour the overall CO2/CO selectivity of the membranes by reducing the diffusivity of the lighter CO molecule in the ca. 0.55 nm pores in the zeolite. The model also indicated that the separation performance was limited by the mass transfer resistance in the support and concentration polarisation on the feed side of the membrane.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-7211 (URN)10.1039/C6RA14544B (DOI)000379577800024 ()2-s2.0-84978766579 (Scopus ID)58af75f0-175a-4e0c-ba22-8052ab996b55 (Local ID)58af75f0-175a-4e0c-ba22-8052ab996b55 (Archive number)58af75f0-175a-4e0c-ba22-8052ab996b55 (OAI)
Note
Validerad; 2016; Nivå 2; 20160705 (dankor)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Farzaneh, A., Zhou, M., Antzutkin, O., Bacsik, Z., Hedlund, J., Holmgren, A. & Grahn, M. (2016). Adsorption of Butanol and Water Vapors in Silicalite‑1 Films with a Low Defect Density. Langmuir, 32, 11789-11798
Open this publication in new window or tab >>Adsorption of Butanol and Water Vapors in Silicalite‑1 Films with a Low Defect Density
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2016 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 32, p. 11789-11798Article in journal (Refereed) Published
Abstract [en]

Pure silica zeolites are potentially hydrophobic and have therefore been considered to be interesting candidates for separating alcohols, e.g., 1-butanol, from water. Zeolites are traditionally synthesized at high pH, leading to the formation of intracrystalline defects in the form of silanol defects in the framework. These silanol groups introduce polar adsorption sites into the framework, potentially reducing the adsorption selectivity toward alcohols in alcohol/water mixtures. In contrast, zeolites prepared at neutral pH using the fluoride route contain significantly fewer defects. Such crystals should show a much higher butanol/water selectivity than crystals prepared in traditional hydroxide (OH−) media. Moreover, silanol groups are present at the external surface of the zeolite crystals; therefore, minimizing the external surface of the studied adsorbent is important. In this work, we determine adsorption isotherms of 1-butanol and water in silicalite-1 films prepared in a fluoride (F−) medium using in situ attenuated total reflectance−Fourier transform infrared (ATR−FTIR) spectroscopy. This film was composed of well intergrown, plate-shaped b-oriented crystals, resulting in a low external area. Single-component adsorption isotherms of 1-butanol and water were determined in the temperature range of 35− 80 °C. The 1-butanol isotherms were typical for an adsorbate showing a high affinity for a microporous material and a large increase in the amount adsorbed at low partial pressures of 1-butanol. The Langmuir−Freundlich model was successfully fitted to the 1-butanol isotherms, and the heat of adsorption was determined. Water showed a very low affinity for the adsorbent, and the amounts adsorbed were very similar to previous reports for large silicalite-1 crystals prepared in a fluoride medium. The sample also adsorbed much less water than did a reference silicalite-1(OH−) film containing a high density of internal defects.The results show that silicalite-1 films prepared in a F− medium with a low density of defects and external area are very promising for the selective recovery of 1-butanol from aqueous solutions.

National Category
Other Chemical Engineering Chemical Process Engineering
Research subject
Chemical Technology; Chemistry of Interfaces
Identifiers
urn:nbn:se:ltu:diva-60688 (URN)10.1021/acs.langmuir.6b03326 (DOI)000388156000009 ()2-s2.0-84995812342 (Scopus ID)
Note

Validerad; 2016; Nivå 2; 2016-12-02 (andbra)

Available from: 2016-11-25 Created: 2016-11-25 Last updated: 2018-07-10Bibliographically approved
Faisal, A., Zhou, M., Hedlund, J. & Grahn, M. (2016). Erratum to: Recovery of butanol from model ABE fermentation broths Using MFI adsorbent: A comparison between traditional beads and a structured adsorbent in the form of a film (ed.). Adsorption, 22(3), 409
Open this publication in new window or tab >>Erratum to: Recovery of butanol from model ABE fermentation broths Using MFI adsorbent: A comparison between traditional beads and a structured adsorbent in the form of a film
2016 (English)In: Adsorption, ISSN 0929-5607, E-ISSN 1572-8757, Vol. 22, no 3, p. 409-Article in journal, Editorial material (Refereed) Published
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-12599 (URN)10.1007/s10450-016-9782-0 (DOI)000372598400012 ()2-s2.0-84959342163 (Scopus ID)bc25ce80-746d-4076-8012-2125f597034d (Local ID)bc25ce80-746d-4076-8012-2125f597034d (Archive number)bc25ce80-746d-4076-8012-2125f597034d (OAI)
Note

Godkänd; 2016; 20160307 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Faisal, A., Zhou, M., Hedlund, J. & Grahn, M. (2016). Recovery of butanol from model ABE fermentation broths Using MFI adsorbent: A comparison between traditional beads and a structured adsorbent in the form of a film (ed.). Adsorption, 22(2), 205-214
Open this publication in new window or tab >>Recovery of butanol from model ABE fermentation broths Using MFI adsorbent: A comparison between traditional beads and a structured adsorbent in the form of a film
2016 (English)In: Adsorption, ISSN 0929-5607, E-ISSN 1572-8757, Vol. 22, no 2, p. 205-214Article in journal (Refereed) Published
Abstract [en]

Butanol, a promising biofuel, can be produced by ABE (acetone, butanol and ethanol) fermentation using e.g. Clostridium acetobutylicum. However, the butanol concentration in the resulting broth is limited to only ca. 20 g/L due to the toxicity for the microorganisms. This low product concentration demands an efficient recovery process for successful commercialization of this process. In this study, a structured adsorbent in the form of steel monolith coated with a silicalite-1 film was prepared using the in situ growth method. The adsorbent was carefully characterized by SEM and XRD. The performance of the adsorbent was evaluated by performing breakthrough experiments at room temperature using model ABE fermentation broths and the performance was compared with that of traditional adsorbents in the form of beads. The structured silicalite-1 adsorbent showed less saturation loading time as compared to commercial binder free silicalite-1 beads, reflecting the different dimensions of the columns used, set by experimental constraints. Studies of the desorption process showed that by operating at appropriate conditions, butanol with high concentration i.e. up to 95.2 wt% for butanol–water model system and 88.5 wt% for ABE fermentation broth can be obtained using the structured silicalite-1 adsorbent. Commercial silicalite-1 beads also showed good selectivity but the concentration of butanol in the desorbed product was limited to 70 % for the butanol–water model system and 69 % for ABE fermentation broth, probably as a result of entrained liquid between the beads.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-9027 (URN)10.1007/s10450-016-9759-z (DOI)000371234200010 ()2-s2.0-84957434968 (Scopus ID)79653da1-6c61-431c-bf70-59c334e8bd7f (Local ID)79653da1-6c61-431c-bf70-59c334e8bd7f (Archive number)79653da1-6c61-431c-bf70-59c334e8bd7f (OAI)
Note

Validerad; 2016; Nivå 2; 20160105 (magr)

Available from: 2016-09-29 Created: 2016-09-29 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
Zhou, M., Korelskiy, D., Ye, P., Grahn, M. & Hedlund, J. (2014). A Uniformly Oriented MFI Membrane for Improved CO2 Separation (ed.). Paper presented at . Angewandte Chemie, 126(13), 3560-3563
Open this publication in new window or tab >>A Uniformly Oriented MFI Membrane for Improved CO2 Separation
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2014 (English)In: Angewandte Chemie, ISSN 0044-8249, Vol. 126, no 13, p. 3560-3563Article in journal (Refereed) Published
Abstract [en]

Membrane separation of CO2 from natural gas, biogas, synthesis gas, and flu gas is a simple and energy-efficient alternative to other separation techniques. But results for CO2-selective permeance have always been achieved by randomly oriented and thick zeolite membranes. Thin, oriented membranes have great potential to realize high-flux and high-selectivity separation of mixtures at low energy cost. We now report a facile method for preparing silica MFI membranes in fluoride media on a graded alumina support. In the resulting membrane straight channels are uniformly vertically aligned and the membrane has a thickness of 0.5 μm. The membrane showed a separation selectivity of 109 for CO2/H2 mixtures and a CO2 permeance of 51×10−7 mol m−2 s−1 Pa−1 at −35 °C, making it promising for practical CO2 separation from mixtures

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-13946 (URN)10.1002/ange.201311324 (DOI)d43b3565-7127-4875-b266-b31760c069dd (Local ID)d43b3565-7127-4875-b266-b31760c069dd (Archive number)d43b3565-7127-4875-b266-b31760c069dd (OAI)
Note
Validerad; 2014; 20140304 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-04-04Bibliographically approved
Zhou, M., Korelskiy, D., Ye, P., Grahn, M. & Hedlund, J. (2014). A Uniformly Oriented MFI Membrane for Improved CO2 Separation (ed.). Paper presented at . Angewandte Chemie International Edition, 53(13), 3492-3495
Open this publication in new window or tab >>A Uniformly Oriented MFI Membrane for Improved CO2 Separation
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2014 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 53, no 13, p. 3492-3495Article in journal (Refereed) Published
Abstract [en]

Membrane separation of CO2 from natural gas, biogas, synthesis gas, and flu gas is a simple and energy-efficient alternative to other separation techniques. But results for CO2-selective permeance have always been achieved by randomly oriented and thick zeolite membranes. Thin, oriented membranes have great potential to realize high-flux and high-selectivity separation of mixtures at low energy cost. We now report a facile method for preparing silica MFI membranes in fluoride media on a graded alumina support. In the resulting membrane straight channels are uniformly vertically aligned and the membrane has a thickness of 0.5m. The membrane showed a separation selectivity of 109 for CO2/H-2 mixtures and a CO2 permeance of 51x10(-7)molm(-2)s(-1)Pa(-1) at -35 degrees C, making it promising for practical CO2 separation from mixtures

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-8218 (URN)10.1002/anie.201311324 (DOI)000333001500038 ()24590761 (PubMedID)2-s2.0-84896476984 (Scopus ID)6b024022-b777-4f2c-bc21-d8f500b889af (Local ID)6b024022-b777-4f2c-bc21-d8f500b889af (Archive number)6b024022-b777-4f2c-bc21-d8f500b889af (OAI)
Note
Godkänd; 2014; 20140424 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-7477-4960

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