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Abstract: Two lamellar organosilica films made up of stacks of head-to-head and head-to-tail alkyl bilayers were synthesized by a UV-driven polymerization of n-C18H37SiCl3 and n-C18H37Si(OCH3)3, respectively. In addition to thermogravimetry and small-angle X-ray scattering, the characterization of these multilayer systems was focused on a variety of multinuclear solid-state NMR methods (1H, 29Si, 13C, 2D WISE). The chemical structure of the siloxane interlayer, the alkyl chain conformation and thermal stability were systematically investigated and compared. Through its marked sensitivity to molecular motion, solid-state NMR was used to investigate the effect of interdigitation on alkyl chain dynamics. [Copyright &y& Elsevier]

Abstract: Whereas the hegemony of the Fischer–Tropsch synthesis is well established for the valorization of methane in the case of important gas fields, the methane dehydro-aromatization reaction remains an interesting solution to convert methane obtained as by-product of oil extraction and thus fight against flaring and global warming. Until now, it was generally accepted that the molybdenum is anchored on the Brønsted acid sites of the zeolite as (Mo2O5)2+ species. The molybdenum performs the dehydrogenation and coupling of CH4 to ethylene which is consecutively oligomerized to benzene over the Brønsted acid sites. In the present work, we bring evidence that this picture is actually more complicated than it seems. The Si/Al ratio of the zeolite, and consequently the density of available Brønsted acid sites, plays a dramatic role on the anchoring mode of the molybdenum and on its catalytic activity. [Copyright &y& Elsevier]

Abstract: Binderless beta zeolite has been anchored on a silicon carbide foam with a monolithic shape. The catalytic activity of the resulting composite was evaluated for a Friedel–Crafts reaction carried out in a fixed-bed configuration: the benzoylation of anisole to p-methoxybenzophenone. The results obtained were compared with those of a commercial beta zeolite. Significantly higher product yields along with a stable activity were obtained with the BEA/SiC composite. It has been suggested that the opened structure of the β-SiC foam and the absence of any binder allow a fast desorption of the p-ketone which is the main product of the reaction but also the major source of deactivation due to strong adsorption and/or coke formation inside the microporosity of the zeolite. [Copyright &y& Elsevier]

Nanostructured silicon carbide (SiC) is an exceptional material with numerous applications, for example, in catalysis, biomedicine, high‐performance composites, and sensing. In this study, a fast and scalable method of producing nanostructured SiC from plant materials by magnesiothermic reduction via self‐propagating high‐temperature synthesis (SHS) route was developed. The produced biogenic material possessed a high surface area above 200 m2/g with a SiC crystallite size below 10 nm, which has not been done previously by SHS. This method enables affordable synthesis of the material plant‐based precursors in a reaction that only takes a few seconds, thereby paving a way for nanostructured SiC production in high volumes using renewable resources. The material was also functionalized with carboxylic acid and bisphosphonate moieties, and its use as metal adsorbent in applications such as wastewater remediation was demonstrated. [ABSTRACT FROM AUTHOR]

Photoacid-catalyzed sol–gel polymerization isnow recognizedas a powerful single-step synthetic approach to the synthesis of hybridfilms, which can be distinguished from conventional sol–gelmethods by higher reactivity and a solvent-free process. Despite itsutility, the mechanism is not yet understood, in particular what chemical,physical, and photochemical parameters determine the precise sequence,kinetics, and advancement of this UV inorganic photopolymerization.Here, using mainly transmission real-time Fourier transformed infrared(RT-FTIR) spectroscopy, we characterize in situthehydrolysis–condensation reactions of oligomeric silicon alkoxidesand the formation of byproducts. Systematic review and assessmentof numerous processing variables (relative humidity, film thickness,precursor structure, nature, and the concentration of photoacid generator)prove that the reaction kinetics are controlled by the two independentphenomena: the intrinsic chemical reaction rates and the water vaporpermeation into the film. [ABSTRACT FROM AUTHOR]

In contrast with the conventional CoMoS/alumina catalyst, the use of amorphous mesostructured ZrO2 as support for the dispersion of the CoMoS active phase in deep hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene led to a higher promotion rate and a better sulfidation of the cobalt species. The CoMoS, dispersed over mesostructured amorphous ZrO2 as catalyst, also induced a modification of the main desulfurization way; in this case, a shift towards direct desulfurization selectivity was observed. This result was unexpected regarding the literature. Indeed, the hydrogenated route was observed for commercial zirconia. The designed catalysts are therefore more eco-friendly, since they consume less hydrogen. This implies a better use of the fossil resources. [ABSTRACT FROM AUTHOR]