Charlotte Pham

Efficient Synthesis of Dimethyl Ether over HZSM‐5 Supported on Medium‐Surface‐Area β‐SiC Foam

In this study, we aimed to produce a highly selective and stable catalyst for the production of dimethyl ether by methanol dehydration. The activities were compared of different active phases of the employed system, zeolite HZSM-5 or gamma-alumina, supported on silicon carbide as foam, and it was found that the supported zeolite catalysts are more active than and as selective as the alumina-based catalysts. The as-prepared zeolite/SiC composites reveal good stability in long-term tests in the presence or absence of steam. The high stability is attributed to the presence of highly dispersed micrometer-sized zeolite particles, which make the active sites more accessible to the reactants and promote the quick transfer of the desired product, dimethyl ether, out of the catalyst bed, minimizing deactivation of the catalyst.

1D SiC decoration of SiC macroscopic shapes for filtration devices

The synthesis of a hierarchical support, constituted of a network of SiC nanofibers deposited on a SiC foam host resulting in a ceramic material with a controlled macroscopic shape and associated high specific surface area superior to 50 m2 g−1, has been reported for the first time. The new composite combines the nanoscopic properties of the SiC nanofibers’ network and controlled macroscopic shape and open porosity, typical of a SiC foam structure. The introduction of the nanostructures onto the host material allows a dramatic increase in the effective surface area which is extremely useful for the chosen field of application. This new type of material has been efficiently employed as a diesel particulate filter at high space velocity and without a detrimental pressure drop. In addition, the combination of such a hierarchical structure with high thermal conductivity could give rise to unexpected results in the field of heterogeneous catalysis where the mass and heat transport limitations still need to be improved.

TiO2/β-SiC foam-structured photoreactor for continuous wastewater treatment.

IntroductionThis study of photocatalytic degradation of wastewater was carried out in alveolar cell β-SiC foam-structured photocatalytic reactors working in a recirculation mode. The immobilization of TiO2 on β-SiC foams was efficiently obtained through a sol–gel technique in acidic conditions.DiscussionIn order to optimize degradation yields obtained by the foam-structured prototype reactor for the photocatalytic water treatment, the operating conditions of the photoreactor have been investigated and the efficiency of the process was evaluated by measuring the photocatalytic degradation of Diuron (3-(3,4-dichlorophenyl)-1,1-dimethyl-urea)) under UV irradiation. Kinetic studies were carried out by investigating the influence of different parameters controlling the reaction (TiO2 loading and β-SiC foam cell size). The ageing of TiO2/β-SiC foam photocatalytic materials and the mineralization (TOC, Cl−, NO3− and NH4+) of Diuron were investigated.