The layered silicate RUB-39 can be transformed by topotactic condensation into RUB-41 (RRO), a ze... more The layered silicate RUB-39 can be transformed by topotactic condensation into RUB-41 (RRO), a zeolite with 8-and 10-ring pores. If the layered RUB-39 is first silylated with dichlorodimethylsilane (DCDMS) or hexamethyldisiloxane (HMDS), an interlayer expanded structure is created after calcination. The DCDMS expanded material contains 10-and 12-ring pores instead of 8-and 10-ring pores. Detailed physicochemical characterization showed that the Al content is not significantly changed during the expansion. In the hydroconversion of decane, the expanded materials have a significantly increased activity, as demonstrated by the lower temperatures at which isomerization and cracking occur. Detailed comparison of the product selectivities obtained with RUB-41 or with its expanded analogs shows that the void structure of the expanded materials is significantly less constrained, as reflected in the distribution of methylnonane isomers, of the ethyloctane vs. methylnonane isomers, and in the ratio of monobranched vs. dibranched isomers.
Conversion of linear butenes over ZSM-5 zeolites leads to a large variety of products, from olefi... more Conversion of linear butenes over ZSM-5 zeolites leads to a large variety of products, from olefins to aromatics. At low temperature, these products are mainly olefins from C 3 = to C 13 = , with a predominance of dimeric products. The analysis of the product stream obtained by the reaction of n-butenes over several materials with MFI topology, but with different aluminum content provides evidence for an oligomerization-cracking-realkylation mechanism. The reactions occur predominantly in the catalyst bulk or at the external surface, depending on the amount of coke developed inside the catalyst. This behavior is determined by the concentration of framework Al and associated silanol groups, inducing coking. For Al-rich MFI samples, the amount of hard coke is sufficient to block the access of reactants to internal acid sites. As a result, extra-crystalline catalysis dominates, while the appearance of the individual products is consistent with that predicted by classical carbocation theory. For siliceous samples, hard coke formation is less pronounced, and evidence for shape selective product formation is present. Expected relations among structural, morphological and acidic properties of all MFI materials have been confirmed by XRD, SEM and BET and by 27 Al MAS NMR, NH 3-TPD and FTIR.
International Journal of Coal Geology, Oct 1, 2014
The full-text may be used and/or reproduced, and given to third parties in any format or medium, ... more The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Conversion of linear butenes over ZSM-5 zeolites leads to a large variety of products, from olefi... more Conversion of linear butenes over ZSM-5 zeolites leads to a large variety of products, from olefins to aromatics. At low temperature, these products are mainly olefins from C 3 = to C 13 = , with a predominance of dimeric products. The analysis of the product stream obtained by the reaction of n-butenes over several materials with MFI topology, but with different aluminum content provides evidence for an oligomerization-cracking-realkylation mechanism. The reactions occur predominantly in the catalyst bulk or at the external surface, depending on the amount of coke developed inside the catalyst. This behavior is determined by the concentration of framework Al and associated silanol groups, inducing coking. For Al-rich MFI samples, the amount of hard coke is sufficient to block the access of reactants to internal acid sites. As a result, extra-crystalline catalysis dominates, while the appearance of the individual products is consistent with that predicted by classical carbocation theory. For siliceous samples, hard coke formation is less pronounced, and evidence for shape selective product formation is present. Expected relations among structural, morphological and acidic properties of all MFI materials have been confirmed by XRD, SEM and BET and by 27 Al MAS NMR, NH 3-TPD and FTIR.
Le Centre pour la Communication Scientifique Directe - HAL - Archive ouverte HAL, Apr 3, 2019
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Dredged river sediments produce a huge volume of mineral materials, which could be incorporated i... more Dredged river sediments produce a huge volume of mineral materials, which could be incorporated into building materials. Considering the raw sediment preparation, mineral processing techniques fit perfectly to this purpose. This work describes two procedures to prepare river sediments, according to the final beneficial use. The first is a dry procedure of deagglomeration to prepare river sediments with the aim of being incorporated into a concrete formulation to build a bicycle path. A large amount of deagglomerated sediment was prepared, requiring upscaling of the deagglomeration process. Successive steps of sieving and roll crushing were used to obtain deagglomerated sediments. To use it as raw material to produce pozzolanic materials and lightweight aggregates, a second procedure consisting of a wet classification at 63 µm was carried out. Steps of wet sieving, followed by hydrocycloning and screw classifying, were used to prepare several silt fractions under 63 µm.
The Interreg FWVL VALSE project aims to promote sustainable dredged sediment reuse. Reuse options... more The Interreg FWVL VALSE project aims to promote sustainable dredged sediment reuse. Reuse options and supporting research were investigated during an earlier project. In order to provide waterways operators and related industries, with case studies, full scale pilot tests are planned at Belgian and French sites. A former sediment disposal site of the French Waterways (VNF) at Saint Omer, Northern France, is considered as a potential source of mature sediment (14 to 40 years old) for reuse applications (landscaping, cycle paths, dikes). Sediments are now comparable to soil in terms of water content and mechanical behaviour. Sediment environmental characteristics are assessed with laboratory methods, and its variability with on-site methods...
Beneficial use of dredged sediments, either in harbours or waterways, is based on their potential... more Beneficial use of dredged sediments, either in harbours or waterways, is based on their potential as alternative resources. Such sediments can be considered as bulk materials for industrial needs, which is predicated on their current waste status or meeting end-of-waste constraints. They also can be an integral part of beneficial use projects using sediments as a bulk component, including civil engineering and landscaping. This is particularly important for beneficial use projects focusing on climate change effects mitigation, such as flood protection works, coastline defence or littoral urban areas redevelopment. When dredged sediment is used as a bulk material, its acceptability is based on an assumed homogeneity of its properties. On-site analyses allow pre-dredging detailed mapping at a denser scale than laboratory ones; monitoring dredgings during operations and during processing; and continuous control of their properties at the implementation site. This is currently possible ...
Conversion of linear butenes over ZSM-5 zeolites leads to a large variety of products, from olefi... more Conversion of linear butenes over ZSM-5 zeolites leads to a large variety of products, from olefins to aromatics. At low temperature, these products are mainly olefins from C 3 = to C 13 = , with a predominance of dimeric products. The analysis of the product stream obtained by the reaction of n-butenes over several materials with MFI topology, but with different aluminum content provides evidence for an oligomerization-cracking-realkylation mechanism. The reactions occur predominantly in the catalyst bulk or at the external surface, depending on the amount of coke developed inside the catalyst. This behavior is determined by the concentration of framework Al and associated silanol groups, inducing coking. For Al-rich MFI samples, the amount of hard coke is sufficient to block the access of reactants to internal acid sites. As a result, extra-crystalline catalysis dominates, while the appearance of the individual products is consistent with that predicted by classical carbocation theory. For siliceous samples, hard coke formation is less pronounced, and evidence for shape selective product formation is present. Expected relations among structural, morphological and acidic properties of all MFI materials have been confirmed by XRD, SEM and BET and by 27 Al MAS NMR, NH 3-TPD and FTIR.
The full-text may be used and/or reproduced, and given to third parties in any format or medium, ... more The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.
The layered silicate RUB-39 can be transformed by topotactic condensation into RUB-41 (RRO), a ze... more The layered silicate RUB-39 can be transformed by topotactic condensation into RUB-41 (RRO), a zeolite with 8-and 10-ring pores. If the layered RUB-39 is first silylated with dichlorodimethylsilane (DCDMS) or hexamethyldisiloxane (HMDS), an interlayer expanded structure is created after calcination. The DCDMS expanded material contains 10-and 12-ring pores instead of 8-and 10-ring pores. Detailed physicochemical characterization showed that the Al content is not significantly changed during the expansion. In the hydroconversion of decane, the expanded materials have a significantly increased activity, as demonstrated by the lower temperatures at which isomerization and cracking occur. Detailed comparison of the product selectivities obtained with RUB-41 or with its expanded analogs shows that the void structure of the expanded materials is significantly less constrained, as reflected in the distribution of methylnonane isomers, of the ethyloctane vs. methylnonane isomers, and in the ratio of monobranched vs. dibranched isomers.
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