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Mosca, Alessandra
Publications (9 of 9) Show all publications
Rezaei, F., Mosca, A., Hedlund, J., Webley, P., Grahn, M. & Mouzon, J. (2011). The effect of wall porosity and zeolite film thickness on the dynamic behavior of adsorbents in the form of coated monoliths (ed.). Paper presented at . Separation and Purification Technology, 81(2), 191-199
Open this publication in new window or tab >>The effect of wall porosity and zeolite film thickness on the dynamic behavior of adsorbents in the form of coated monoliths
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2011 (English)In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 81, no 2, p. 191-199Article in journal (Refereed) Published
Abstract [en]

The effects of wall porosity, channel width distribution and zeolite film thickness on the performance of 400 and 1200 cells per square inch (cpsi) cordierite monoliths coated with zeolite X films with thicknesses of 1.5 and 2.5 μm were examined. To investigate the effect of wall porosity and restrict growth of zeolite to the external surface of the monolith channels, the macro pores in the walls of the 1200 cpsi cordierite monoliths were filled with colloidal α-alumina particles. The adsorbents were characterized by Scanning Electron Microscopy, Mercury Intrusion Porosimetry and carbon dioxide breakthrough experiments and a mathematical model describing the diffusion and adsorption in the system was fitted to the data. The model accounted for carbon dioxide uptake by filling the pores in the support by carbon dioxide gas and adsorption of carbon dioxide on cordierite, alumina and zeolite. The model indicates that the uptake of carbon dioxide by adsorption on cordierite is much slower than by pore filling and too slow to influence the very fast breakthrough experiments with monoliths without zeolite film that are over in less than 1 minute. It was shown that the pores in the cordierite monolith result in dispersion by pore filling with carbon dioxide gas, not adsorption. The CO2 adsorption capacity of a 1200 cpsi monolith coated with a 2.5 μm film was 0.13 mmol/cm3 adsorbent, which should be compared to the adsorption capacity of zeolite X beads, which is about 2.3 mmol/cm3 adsorbent. To increase adsorption capacity of a non-porous zeolite coated monolith, film thickness could be increased. The model indicated that the film thickness could be increased up to about 10 μm without increasing the dispersion and thereby approach the adsorption capacity for beads. However, simulation of the whole cycle must be performed in order to find the optimum film thickness for a real cyclic process. This work has lead to better understanding of the role of the support porosity and pore size distribution and film thickness for coated monolith adsorbents.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-12441 (URN)10.1016/j.seppur.2011.07.027 (DOI)000296108500010 ()2-s2.0-80052422013 (Scopus ID)b9717b71-b7fc-4247-abbe-92989c57b3d0 (Local ID)b9717b71-b7fc-4247-abbe-92989c57b3d0 (Archive number)b9717b71-b7fc-4247-abbe-92989c57b3d0 (OAI)
Note
Validerad; 2011; 20110808 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Rezaei, F., Mosca, A., Webley, P., Hedlund, J. & Xiao, P. (2010). Comparison of traditional and structured adsorbents for CO2 separation by vacuum swing adsorption (ed.). Paper presented at . Industrial & Engineering Chemistry Research, 49(10), 4832-4841
Open this publication in new window or tab >>Comparison of traditional and structured adsorbents for CO2 separation by vacuum swing adsorption
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2010 (English)In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 49, no 10, p. 4832-4841Article in journal (Refereed) Published
Abstract [en]

The development of structured adsorbents with attractive characteristics is an important step in the improvement of adsorption-based gas-separation processes. The improved features of structured adsorbents include lower energy consumption, higher throughput, and superior recovery and purity of product because of the even flow distribution, very low mass-transfer resistance, and low pressure drop in combination with a reasonable adsorption capacity. This study examines the vacuum-swing adsorption (VSA) CO2 separation performance of structured adsorbents in the form of thin NaX films grown on the walls of ceramic cordierite monoliths, and the results are compared with NaX pellets. Adsorption equilibrium and dynamic properties are explored experimentally. The CO2 breakthrough front for the NaX film grown on the 400 cells/in.2 (cpsi) monolith was close to ideal and indicated that axial dispersion was very small and that the mass-transfer resistance in the film was very low. The breakthrough front for the structured adsorbent with 400 cpsi was sharper than that for the structured adsorbent with 900 cpsi and only shifted to shorter breakthrough times because of the lower amount of zeolite and higher effective diffusivity of the former sample. In addition, the CO2 breakthrough fronts for the 400 and 900 cpsi structured adsorbents were both sharper than the breakthrough front for NaX beads. This indicates that the flow distribution in the structured adsorbents is more even and that the mass-transfer resistance in the film is very low because of the small film thickness and high effective diffusivity for CO2 in the NaX film. Experimental data were used to obtain overall mass-transfer linear-driving-force constants, which were subsequently used in a numerical simulation program to estimate the performance of the adsorbents for CO2/N2 separation in a VSA process. It was found that the recovery of structured adsorbents was superior to that of a packed bed because of the much shorter mass-transfer zone. The purity, on the other hand, was not as high as that obtained with a packed bed because of excessive voidage in the structured adsorbents. Increased cell density or improved zeolite loading of the structured adsorbents would improve the CO2 purity without sacrificing recovery for the structured adsorbents, and this represents a path forward to improved VSA performance for CO2 capture.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-10549 (URN)10.1021/ie9016545 (DOI)000277443100042 ()2-s2.0-77952354397 (Scopus ID)95f46790-c951-11de-b769-000ea68e967b (Local ID)95f46790-c951-11de-b769-000ea68e967b (Archive number)95f46790-c951-11de-b769-000ea68e967b (OAI)
Note
Validerad; 2010; 20091104 (linste)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mosca, A., Hedlund, J., Webley, P., Grahn, M. & Rezaei, F. (2010). Structured zeolite NaX coatings on ceramic cordierite monolith supports for PSA applications (ed.). Paper presented at . Microporous and Mesoporous Materials, 130(1-3), 38-48
Open this publication in new window or tab >>Structured zeolite NaX coatings on ceramic cordierite monolith supports for PSA applications
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2010 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 130, no 1-3, p. 38-48Article in journal (Refereed) Published
Abstract [en]

Novel structured adsorbents in the form of thin zeolite films grown on substrates designed for low pressure drop have a great potential to improve pressure swing adsorption (PSA) processes. In the present work, template free films of NaX zeolite were grown on the walls of ceramic cordierite supports using a seeding technique. The supports had 400 parallel channels per square inch. Films were grown both from a gel and a clear synthesis solution. The materials were analyzed by scanning electron microscopy, X-ray diffraction, N2 adsorption/desorption measurements, Hg-porosimetry as well as CO2 breakthrough experiments. When a gel was used for film growth, a film consisting of well intergrown crystals with a thickness of about 1 μm was obtained. However, a large amount of sediments were deposited on top of the film, which resulted in a dispersed CO2 adsorption breakthrough front. Zeolite films grown in one longer hydrothermal treatment in a clear solution were less intergrown and consisted of both NaX and hydroxysodalite crystals and, in addition, some sediments were deposited on top of the film, which again resulted in a dispersed breakthrough front. By using a multiple-step synthesis procedure and a clear synthesis solution, well intergrown NaX films, free from sediments and with only a very small fraction of hydroxysodalite crystals could be prepared. The CO2 breakthrough front for the latter adsorbent was sharper than the front for an empty adsorption column and only shifted in time. This indicates that the flow distribution in the adsorbent is even and that the mass transfer resistance in the film is very low due to the small film thickness and high effective diffusivity for CO2 in the NaX film and still, the adsorption capacity is considerable. The even flow distribution, very low mass transfer resistance and low pressure drop in combination with considerable adsorption capacity in this adsorbent indicates that it is a promising adsorbent for PSA applications. The findings from the present work will be important for the development of structured adsorbents to use as a competitive alternative to traditionally used adsorbents in PSA.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-14557 (URN)10.1016/j.micromeso.2009.10.010 (DOI)000275702600007 ()2-s2.0-76049125172 (Scopus ID)dee3dd30-908c-11de-8da0-000ea68e967b (Local ID)dee3dd30-908c-11de-8da0-000ea68e967b (Archive number)dee3dd30-908c-11de-8da0-000ea68e967b (OAI)
Note
Validerad; 2010; 20090824 (linste)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mosca, A., Öhrman, O., Hedlund, J., Indra, P. & Creaser, D. (2009). NO2 and N-2 sorption in MFI films with varying Si/Al and Na/Al ratios (ed.). Microporous and Mesoporous Materials, 120(3), 195-205
Open this publication in new window or tab >>NO2 and N-2 sorption in MFI films with varying Si/Al and Na/Al ratios
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2009 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 120, no 3, p. 195-205Article in journal (Refereed) Published
Abstract [en]

MFI crystals or films with controlled thicknesses and different Si/Al ratios were grown on seeded cordierite monoliths using a clear synthesis mixture with template or a template-free gel. The materials were analyzed by scanning electron microscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectrometry, X-ray photoelectron spectroscopy, thermogravimetric analysis and sorption experiments using N2 or NO2 adsorbates. The films were uniformly distributed over the support surface. As expected, the specific monolayer N2 adsorption capacity (mol/gzeolite) was constant and independent of film thickness. The specific molar NO2 adsorption capacity was significantly lower than the specific molar monolayer N2 adsorption capacity, indicating that NO2 is adsorbed at specific sites rather than evenly distributed in a monolayer. A number of NO2 adsorption sites with varying strengths were observed by TPD experiments. At 30 °C, the amount of adsorbed NO2 in the MFI films increased with increasing Al and Na content as opposed to the N2 adsorption capacity, which was independent of these parameters. At 200 °C, the adsorbed amount of NO2 was lower than at 30 °C and apparently independent on Al concentration in the Na-MFI films. These results indicate that different mechanisms are involved in NO2 adsorption. NO2 may adsorb weakly on Na+ cations and also react with silanol groups and residual water in the zeolite, the latter two results in more strongly bound species. Upon NO2 adsorption, formation of NO was observed. This work represents the first systematic study of the effects of Al and Na content on NO2 adsorption in MFI films.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-11450 (URN)10.1016/j.micromeso.2008.10.018 (DOI)000264971200002 ()2-s2.0-60949111945 (Scopus ID)a69f8d10-3098-11de-bd0f-000ea68e967b (Local ID)a69f8d10-3098-11de-bd0f-000ea68e967b (Archive number)a69f8d10-3098-11de-bd0f-000ea68e967b (OAI)
Note

Validerad; 2009; 20090424 (bajo)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mosca, A. (2009). Structured zeolite adsorbents for PSA applications (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Structured zeolite adsorbents for PSA applications
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Zeolites are microporous crystalline aluminosilicates with unique properties, and are therefore used in adsorption processes, for membrane separation, and as catalysts. Thin zeolite films grown on honeycomb monolith supports represent a new type of material and may be used as structured catalysts and adsorbents, and improve the processes significantly.Pressure swing adsorption (PSA) and vacuum swing adsorption (VSA) are commonly used technologies for gas separation. Currently, adsorbents in form of zeolite beads or pellets are used in PSA and VSA processes. Although these adsorbents exhibit high adsorption capacity, the main drawback of these materials is the limited mass- and heat-transfer, which reduce the performance of the PSA and VSA processes.Novel structured adsorbents with reduced heat and mass transfer limitations may represent a competitive alternative to currently used adsorbents. In this work novel adsorbents in the form of thin zeolite films of NaX and ZSM-5 type were grown on ceramic cordierite monoliths and the CO2 and NOx adsorption properties were studied. NaX zeolite films with controllable thickness and free from sediments were grown with a multiple step synthesis procedure on the walls of porous ceramic cordierite monolith supports with different cell density.The structured adsorbents have lower adsorption capacity per gram adsorbent compared to beads. However, the pressure drop for the structured adsorbents is much lower than for beads.CO2 breakthrough fronts for the best structured NaX adsorbents were much sharper than for NaX beads. The sharp breakthrough fronts indicate that the flow distribution in the structured adsorbent is even and that the mass transfer resistance is very low due to the small film thickness and high effective diffusivity for CO2 in the film. At the same time, the adsorption capacity of the structured adsorbents is considerable.NOx adsorption for structured ZSM-5 adsorbents with varying Si/Al and Na/Al ratio was also systematically studied for the first time. An increased aluminium and sodium content in the films resulted in a higher amount of physisorbed NO2 at low temperature, due to increased number of weak adsorption sites. At higher temperature, the amount of NO2 adsorbed was nearly independent of aluminium and sodium concentration for all ZSM-5 film samples, which indicated that an increase in Al and Na concentration in the films increased only the number of weak adsorption sites.The VSA separation performance of the structured adsorbents was compared with that of adsorbent beads by numerical simulation. These results demonstrate the potential advantage of structured adsorbents, in particular in rapid cycle adsorption processes. The even flow distribution, very low mass transfer resistance and low pressure drop in combination with considerable adsorption capacity in the best structured adsorbents indicate that these novel materials are promising adsorbents for PSA and VSA applications.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2009. p. 45
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Natural sciences - Chemistry, Naturvetenskap - Kemi
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-26404 (URN)e1f0b7c0-c3c0-11de-b769-000ea68e967b (Local ID)978-91-7439-024-7 (ISBN)e1f0b7c0-c3c0-11de-b769-000ea68e967b (Archive number)e1f0b7c0-c3c0-11de-b769-000ea68e967b (OAI)
Note

Godkänd; 2009; 20091028 (alemos); DISPUTATION Ämnesområde: Kemisk teknologi/Chemical Technology Opponent: Professor Joeri Denayer, Vrije University, Belgien Ordförande: Professor Jonas Hedlund, Luleå tekniska universitet Tid: Fredag den 27 november 2009, kl 10.00 Plats: F 531, Luleå tekniska universitet

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-03-15Bibliographically approved
Mosca, A., Hedlund, J., Ridha, F. & Webley, P. (2008). Optimization of synthesis procedures for structured PSA adsorbents (ed.). Paper presented at . Adsorption, 14(4-5), 687-693
Open this publication in new window or tab >>Optimization of synthesis procedures for structured PSA adsorbents
2008 (English)In: Adsorption, ISSN 0929-5607, E-ISSN 1572-8757, Vol. 14, no 4-5, p. 687-693Article in journal (Refereed) Published
Abstract [en]

Structured adsorbents in the form of supported thin zeolite films may represent a competitive alternative to traditional zeolite adsorbents in form of beads or pellets used in PSA processes, due to the reduction of mass- and heat-transfer limitations typical of packed beds. Thin NaX films were grown by hydrothermal treatment using a clear solution on cordierite monoliths. Films grown by a multiple synthesis procedure were dense and uniform with a very small amount of sediments adjacent to the film, which may be an advantage in PSA applications. The CO2 adsorption capacity and the pressure drop for the supported films were compared to those of a packed NaX bed. Although the adsorption capacity of the column filled with the structured adsorbents was 67 times lower than when the column was filled with zeolite beads, the pressure drop was 100 times lower for the structured adsorbent. The adsorption capacity can be increased by increasing the film thickness or the cell density of the monoliths without increasing the pressure drop significantly, indicating the potential advantage of structured adsorbents in PSA processes. Further investigations are needed in order to prove this hypothesis.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-11340 (URN)10.1007/s10450-008-9126-9 (DOI)000259188800026 ()2-s2.0-52149103179 (Scopus ID)a4961840-7379-11dd-a60f-000ea68e967b (Local ID)a4961840-7379-11dd-a60f-000ea68e967b (Archive number)a4961840-7379-11dd-a60f-000ea68e967b (OAI)
Note
Validerad; 2008; 20080826 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mosca, A., Hedlund, J., Ridha, F. & Webley, P. A. (2007). Optimization of synthesis procedures for structured PSA adsorbents (ed.). Paper presented at Fundamentals of Adsorption : 20/05/2007 - 25/05/2007. Paper presented at Fundamentals of Adsorption : 20/05/2007 - 25/05/2007.
Open this publication in new window or tab >>Optimization of synthesis procedures for structured PSA adsorbents
2007 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-28479 (URN)24bc95e0-7cc6-11dc-b50c-000ea68e967b (Local ID)24bc95e0-7cc6-11dc-b50c-000ea68e967b (Archive number)24bc95e0-7cc6-11dc-b50c-000ea68e967b (OAI)
Conference
Fundamentals of Adsorption : 20/05/2007 - 25/05/2007
Note
Godkänd; 2007; 20071017 (linste)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Mosca, A. & Hedlund, J. (2007). Optimizing synthesis conditions and support type for structured PSA adsorbents (ed.). Paper presented at International Zeolite Conference : 12/08/2007 - 17/08/2007. Paper presented at International Zeolite Conference : 12/08/2007 - 17/08/2007.
Open this publication in new window or tab >>Optimizing synthesis conditions and support type for structured PSA adsorbents
2007 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

Thin faujasite films were grown on porous and dense cordierite monoliths by hydrothermal treatment using a gel or a clear solution. A well defined FAU film with a thickness of about 1 μm could be grown on both supports using the gel. However, a relatively high weight gain after synthesis was recorded for the porous monoliths due to zeolite crystallization in the pores, which may be undesirable for PSA applications. The films grown in the clear solution consisted of both FAU and sodalite crystals and the thickness of the FAU film was about 0.5 μm. A 5 times lower weight gain was observed and much less zeolite grew in the pores of the support, which may be an advantage for PSA applications. The adsorption properties of the samples are currently under investigation.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-28517 (URN)2559d230-7cc4-11dc-b50c-000ea68e967b (Local ID)2559d230-7cc4-11dc-b50c-000ea68e967b (Archive number)2559d230-7cc4-11dc-b50c-000ea68e967b (OAI)
Conference
International Zeolite Conference : 12/08/2007 - 17/08/2007
Note
Godkänd; 2007; 20071017 (linste)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Mosca, A. (2007). Structured zeolite adsorbents (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Structured zeolite adsorbents
2007 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Zeolites are microporous crystalline aluminosilicates with unique properties, and therefore used in adsorption processes, for membrane separation, in catalysis, and in sensor technologies. Pressure swing adsorption (PSA) is a commonly used technology for purifying gases and is based on the ability of materials like zeolites, to selectively adsorb and desorb particular gas molecules as the gas pressure is increased and reduced, respectively. Adsorbents in form of beads and extrudates are traditionally used in PSA processes. When using materials in this form, there is a trade-off between pressure drop and heat- and mass-transfer limitations. Novel structured adsorbents with low pressure drop and reduced heat- and mass-transfer limitations may represent a competitive alternative to traditionally used adsorbents. Thin zeolite films grown on monolith substrates may be particularly suitable for the purpose. In this work, thin NaX and MFI zeolite films were grown on ceramic cordierite monoliths and the adsorption of CO2 and NOx was measured. NaX zeolite films with controllable thickness were grown on cordierite monoliths with different cell density. In this study, suitable synthesis conditions for the growth of supported NaX films were identified. The CO2 adsorption capacity and the pressure drop for the supported films were compared to those of a packed NaX bed. Although the adsorption capacity per gram sample was 25 times lower, the pressure drop of the structured adsorbent was 100 times lower than the NaX packed bed, indicating the potential advantage of structured adsorbents in PSA processes. NOx adsorption on supported MFI films with varying Si/Al and Na/Al ratio was also studied. An increase of Al and Na content in the films results in a higher amount of physisorbed NO2 at low temperature, due to an increase in the number of weak adsorption sites. At higher temperature, the amount of NO2 adsorbed was nearly independent of aluminum and sodium concentration for all MFI film samples. The results from this work indicate that novel structured adsorbents based on supported thin NaX and MFI zeolite films represent a competitive alternative to traditional adsorbents and can be used as selective adsorbents for CO2 and NOx adsorption.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2007. p. 125
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757 ; 2007:47
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-18045 (URN)68592df0-781a-11dc-80da-000ea68e967b (Local ID)68592df0-781a-11dc-80da-000ea68e967b (Archive number)68592df0-781a-11dc-80da-000ea68e967b (OAI)
Note
Godkänd; 2007; 20071011 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved

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