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We report the first synthesis of a powdery heterogeneous catalyst using spark ablation technology. A TiO2 powder is aerosolized in a vortex and injected close to the electrode of a spark ablation nanoparticle generator, to be decorated with Ni nanoparticles. The resulting Ni/TiO2 catalyst is readily active in the hydrogenation of CO2 to methane. [ABSTRACT FROM AUTHOR]

Ruthenium catalysts supported on TiO2 have been shown to have competitive activity and selectivity for the methanation of CO2. In particular, a catalyst using preformed RuO2 nanoparticles deposited on a TiO2 support showed competitive performances in a previous study. In this work, ambient-pressure X-ray photoelectron spectroscopy was employed to determine the chemical state of this catalyst under reaction conditions. The active state of ruthenium was found to be the metallic one. Surface adsorbates were monitored in the steady state, and CHx species were found to be favored over adsorbed carbon monoxide at increasing temperatures.

This paper focuses on the hydrogenolysis of 2‐phenoxy‐1‐phenylethanone, modelling a pre‐oxidized form of lignin using five catalysts of similar metal content, prepared by impregnation of Ni(II), Rh(III) and both metals onto Aerosil‐380 in the presence of NH3, followed by a reduction step. The materials were characterized in the dried as‐synthesized state and after consecutive reductive and oxidative treatments, showing the great dispersion of the metal (oxide nanoparticles with sizes<2 nm). Working with 1 mol % of the reduced metal (500 °C) per substrate at 180 °C with isopropanol as H‐donor, the most active catalyst, but also the least selective towards phenol, was initially found to be the Ni‐based one. Under similar conditions, the lower capacity of the Rh‐based catalyst to induce H transfer from isopropanol favoured phenol formation but resulted in much slower C−OAr cleavage. Despite a very high dispersion of the two metals in the bimetallic catalysts, no synergy was found, suggesting that Ni would be segregated at the surface. Finally, the best phenol productivity could be reached by reducing the Ni‐based catalyst at 650 °C, which led to a more efficient cleavage of C−OAr bonds. In this way, it was possible to produce 8 times more phenol per hour. [ABSTRACT FROM AUTHOR]

Magnesium silicates combining acidic and basic surface properties are known to be interesting as heterogeneous catalysts. Nevertheless, their catalytic performances are highly dependent on the synthesis method used. In this study, a series of magnesium silicates was synthesized for the first time using a coprecipitation method with a micromixer. It is first shown that changes in synthesis/precipitation pH led to magnesium silicates with different Mg/Si ratios: the higher the synthesis pH, the higher the Mg/Si ratio. Moreover, prepared silicates with a final Mg/Si ratio greater than 0.7, thus prepared at high pH, exhibit negligible specific surface area, whereas relatively high values (>180 m2/g) have been obtained for lower Mg/Si ratios. A set of experimental characterization data obtained by N2 physisorption, SEM, XRD, TGA-DTA as well as Raman and 29Si NMR spectroscopies are presented and discussed. They show the existence of two distinct families with a similar Magnesium Silicate Hydrate (MSH) phase, but they reveal different aggregation states and textural properties. Finally, the surface acid–base reactivity of the co-precipitated magnesium silicates was determined using the model reaction of 2-methylbut-3-yn-2-ol (MBOH) conversion. The results obtained suggest that it is possible to prepare silicates with a wide range of surface acid–base properties, from purely basic solids to those with both acidic and basic properties, by adjusting the final Mg/Si ratio via the control of the synthesis parameters. [ABSTRACT FROM AUTHOR]

Mixed‐anion compounds widen the chemical space of attainable materials compared to single anionic compounds, but the exploration of their structural diversity is limited by common synthetic paths. Especially, oxychlorides rely mainly on layered structures, which suffer from low stability during photo(electro)catalytic processes. Herein we report a strategy to design a new polar 3D tetrahedral framework with composition Zn4Si2O7Cl2. We use a molten salt medium to enable low temperature crystallization of nanowires of this new compound, by relying on tetrahedral building units present in the melt to build the connectivity of the oxychloride. These units are combined with silicon‐based connectors from a non‐oxidic Zintl phase to enable precise tuning of the oxygen content. This structure brings high chemical and thermal stability, as well as strongly anisotropic hole mobility along the polar axis. These features, associated with the ability to adjust the transport properties by doping, enable to tune water splitting properties for photoelectrocatalytic H2 evolution and water oxidation. This work then paves the way to a new family of mixed‐anion solids [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of CO2 into CH4 is an effective method to convert waste CO2 and green hydrogen into clean fuel on a large scale. However, the viability of such process largely relies on the development of highly active heterogeneous catalysts. Here, a tailored methanation catalyst, Co nanoparticles immobilized into a highly porous N‐doped carbon matrix, is prepared by the carbonization of a cobalt‐based layered zeolitic imidazolate framework (ZIF−L) material under an argon atmosphere. This catalyst displays a specific activity of 22.3 molCH4/gcat.min at 350 °C, significantly outperforming a similar catalyst derived from the more conventional ZIF‐67 (11.7 molCH4/gcat.min). This is explained by the stabilization of small Co nanoparticles (∼20 nm) and by the presence of abundant medium‐strength basic sites related to the nitrogen doping in the catalyst prepared from ZIF−L. Notably, the new catalyst shows high stability; no deactivation is observed up to 60 hours on stream. [ABSTRACT FROM AUTHOR]

Research has been conducted on Mo (sub)7 O (sub)16 (O (sub)3 PCH (sub)2 PO (sub)3) (sub)3] (super)8- compounds with diphosphono-polyoxometalate anions and diprotonated ethylenediamine and piperazine countercations. The hydrothermal synthesis of these compounds has been carried out and the results indicate that the compounds are diamagnetic.

Research has been conducted on hybrid borophosphate-phenylphosphonate polyoxometalate polyanion. The authors report the hydrothermal synthesis of this compound starting from imidazole, molybdenum oxide and phosphoric, boric and phenylphosphonic acids.

Natural abundance 43Ca solid state NMR experiments are reported for the first time at ultra-high magnetic field (35.2 T) on a series of Ca-(pyro)phosphate and Ca-oxalate materials, which are of biological relevance in relation to biomineralization processes and the formation of pathological calcifications. The significant gain in both sensitivity and resolution at 35.2 T leads to unprecedented insight into the structure of both crystalline and amorphous phases. [ABSTRACT FROM AUTHOR]