Etude des proprietes redox d'oxydes de terres rares en tant que supports de catalyseurs par spectroscopies de photoemission et photoabsorption X. Applications a la synthese CO/H2

Available from INIST (FR), Document Supply Service, under shelf-number : T 82541 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

IR spectroscopy evidence of MoS2 morphology change by citric acid addition on MoS2/Al2O3 catalysts – A step forward to differentiate the reactivity of M-edge and S-edge

International audienc

Fluoride etching opens the structure and strengthens the active sites of the layered ZSM-5 zeolite

International audienc

Pyrolysis investigation of food wastes by TG-MS-DSC technique

International audienc

Fluoride etching opens the structure and strengthens the active sites of the layered ZSM-5 zeolite

International audienceThe NH4F etching is a chemical approach for the preparation of hierarchical zeolites without substantial modification of their framework composition and acidic properties. We employed this approach to modify the 2-dimensional form of ZSM-5 and obtain a catalyst for bulky molecules conversion. The etching conditions were varied in order to obtain hierarchical ZSM-5 with different level of dissolution. Thus, obtained derivatives of 2-dimensional ZSM-5 were thoroughly studied in order to get deep insights into the effect of fluoride treatment. The 2-dimensional ZSM-5 was found unexpectedly stable under etching conditions, which is a consequence of the high quality of zeolite crystals containing a limited number of defect zones and misoriented crystalline domains, in contrast to conventional ZSM-5. Fluoride etching was also used to de-pillar 2-dimensional ZSM-5. The morphology and textural properties of the de-pillared ZSM-5 were very similar to those of the parent layered ZSM-5. Accordingly, amorphous and extra-framework species were dissolved first, resulting in the complete removal of extra-framework Al, thereby strengthening the active sites. In summary, the fluoride etching opens the structure of layered ZSM-5 and strengthens its acid sites when combined with dealumination during calcination

Self-assembled titanosilicate TS-1 nanocrystals in hierarchical structures

International audienceHierarchical structures consisting of microporous titanosilicate TS-1 nanocrystals (MFI-type structure) are obtained by controlled evaporation of colloidal suspensions. The TS-1 nanocrystals with diameter of 60-80 nm are prepared by hydrothermal treatment of clear precursor suspension. The purified TS-1 colloidal suspensions are dried under controlled conditions in order to form hierarchical structures with uniform micropores originated from the TS-1 nanocrystals, mesopores coming from the interparticles spacing and macropores emerging from the controlled evaporation of the solvent. The as-prepared micro/meso/macroporous TS-1 materials are treated by non-thermal plasma to remove the organic template and subsequently characterized by spectroscopy (DLS, IR, UV-vis), microscopy (TEM, SEM), X-ray diffraction, nitrogen sorption and mercury intrusion porosimetry. Besides, the sorption and confinement of 2,4,6-trimethylpyridine (collidine) probe molecule in the micro/meso/macroporous TS-1 structure is followed by FTIR. (C) 2011 Elsevier B.V. All rights reserved

Self-assembled titanosilicate TS-1 nanocrystals in hierarchical structures

International audienceHierarchical structures consisting of microporous titanosilicate TS-1 nanocrystals (MFI-type structure) are obtained by controlled evaporation of colloidal suspensions. The TS-1 nanocrystals with diameter of 60-80 nm are prepared by hydrothermal treatment of clear precursor suspension. The purified TS-1 colloidal suspensions are dried under controlled conditions in order to form hierarchical structures with uniform micropores originated from the TS-1 nanocrystals, mesopores coming from the interparticles spacing and macropores emerging from the controlled evaporation of the solvent. The as-prepared micro/meso/macroporous TS-1 materials are treated by non-thermal plasma to remove the organic template and subsequently characterized by spectroscopy (DLS, IR, UV-vis), microscopy (TEM, SEM), X-ray diffraction, nitrogen sorption and mercury intrusion porosimetry. Besides, the sorption and confinement of 2,4,6-trimethylpyridine (collidine) probe molecule in the micro/meso/macroporous TS-1 structure is followed by FTIR. (C) 2011 Elsevier B.V. All rights reserved

Incorporation of clusters of titanium oxide in Beta zeolite structure by a new cold TiCl4-plasma process: physicochemical properties and photocatalytic activity

International audienceA new post-synthetic approach, involving cold plasma treatment, was employed for the preparation of TiO2–Beta zeolite. Zeolite Beta nanoparticles were first subjected to plasma induced deposition of TiCly (with y ≤ 3), which were further converted into TiOx (with x ≤ 2) upon O2-plasma treatment. Different steps of the new elaborated plasma approach were monitored using in situ FTIR spectroscopy. D2O isotopic exchange was used in order to shed light on the formation of Si–O–Ti bonds induced by TiCl4-plasma followed by O2-plasma treatments. The obtained TiO2–Beta materials were studied by a set of complementary characterization techniques including FTIR, TEM, SEM-EDS, XRD, N2 sorption, NMR and UV-Vis. The silanol content and the acidic properties of TiO2–Beta composites were also studied. The elaborated materials were tested as photocatalysts for methanol photooxidation in the gas phase. TiO2–Beta presents a methanol photooxidation rate 8 times higher than a conventional P25-TiO2 catalyst under UV irradiation

Incorporation of clusters of titanium oxide in Beta zeolite structure by a new cold TiCl4-plasma process: physicochemical properties and photocatalytic activity

International audienceA new post-synthetic approach, involving cold plasma treatment, was employed for the preparation of TiO2–Beta zeolite. Zeolite Beta nanoparticles were first subjected to plasma induced deposition of TiCly (with y ≤ 3), which were further converted into TiOx (with x ≤ 2) upon O2-plasma treatment. Different steps of the new elaborated plasma approach were monitored using in situ FTIR spectroscopy. D2O isotopic exchange was used in order to shed light on the formation of Si–O–Ti bonds induced by TiCl4-plasma followed by O2-plasma treatments. The obtained TiO2–Beta materials were studied by a set of complementary characterization techniques including FTIR, TEM, SEM-EDS, XRD, N2 sorption, NMR and UV-Vis. The silanol content and the acidic properties of TiO2–Beta composites were also studied. The elaborated materials were tested as photocatalysts for methanol photooxidation in the gas phase. TiO2–Beta presents a methanol photooxidation rate 8 times higher than a conventional P25-TiO2 catalyst under UV irradiation