Characterization of VOx-TiO2 catalysts and their activity in the partial oxidation of methyl ethyl ketone

The present work focuses on the partial oxidation of methyl ethyl ketone to acetic acid over TiO₂ supported vanadia catalysts with V loadings from 1 to 13.5 wt.%. In order to elucidate the relation between catalytic activity and the structure of the catalysts, the catalysts were also characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction with hydrogen (TPR), and temperature programmed desorption of lattice oxygen (TPD-O₂). The investigations show that with increasing V loading the MEK conversion increased whereas the turn-over frequency decreased. At lower V loading (1–4 wt.%) the total oxidation to CO_x was favoured and the selectivities to acetic acid and other oxygenated products were low. The highest selectivities to acetic acid were achieved at V loadings of 4–6 wt.%. Based on literature data and our results, a scheme of the reaction pathways for the partial oxidation of MEK to AcOH and other by-products was developed.     

Synthesis and crystal chemistry of the NaMSO4F family (M = Mg, Fe, Co, Cu, Zn)

Our work in metal fluorosulphate chemistry, which was triggered by the discovery of the tavorite-phase of LiFeSO₄F, has unveiled many novel Li- and Na-based phases with desirable electrochemical and/or transport properties. Further exploring this rich crystal chemistry, we have synthesized the Na-based magnesium, copper and zinc fluorosulphates, which crystallise in the maxwellite (tavorite-like framework) structure just as their Fe and Co counterparts, which were previously reported. These phases show ionic conductivities in the range of ∼10⁻⁷ S cm⁻¹ or ∼10⁻¹¹ S cm⁻¹ depending upon their synthesis process and no reversible electrochemical activity versus Na.     

Über Polynome,die in einem gegebenen Intervalle möglichst wenig von Null abweichen

Ohne Zusammenfassung     

The Generalized Buckley–Leverett System: Solvability

We propose a new approach to the mathematical modeling of the Buckley–Leverett system, which describes two-phase flows in porous media. Considering the initial-boundary value problem for a deduced model, we prove the solvability of the problem. The solvability result relies mostly on the kinetic method.     

3-Methoxypyrazoles from 1,1-dimethoxyethene,few original results

From the condensation between 1,1-dimethoxyethene and anhydrides, synthetically useful β,β–dimethoxy–α,β-unsaturated ketones were prepared. Upon addition of hydrazine, followed by iodination, 4-iodinated 3-methoxypyrazoles were obtained. The occurrence of a side compound also provided insights in the scope of this synthesis. In a second part, 1-(4-chlorophenyl)-3,3-dimethoxyprop-2-en-1-one was obtained from 1,1-dimethoxyethene and 4-chlorobenzoylchloride. The subsequent addition of hydrazine or phenylhydrazine led to 5-(4-chlorophenyl)-3-methoxy-1H-pyrazole or 1-phenyl-5-(4-chlorophenyl)-3-methoxypyrazole in unprecedented 64 or 54% overall yield. Unexpectedly, addition of 2-pyridylhydrazine led to the 2-([1,2,4]triazolo[4,3-a]pyridin-3-yl)-1-(4-chlorophenyl) ethanone. This led us to design original conditions, which led to the target 1-(2-pyridyl)-5-(4-chlorophenyl)-3-methoxypyrazole in a 39% overall yield. Additional examples are provided, starting from various carboxychlorides.     

Die Bestimmung des Wismuts und seine Trennung vom Blei und anderen Metallen durch Hydrolyse

Ohne Zusammenfassung     

Effect of binder on the properties of iron oxide sorbent for hot gas desulfurization

The most difficult problem in hot gas desulfurization in Integrated Coal Gasification Combined Cycle (IGCC) is the pulverization of sulfur removal sorbents. Appropriate binders for hot gas sulfur removal sorbents can solve the pulverization problem. In this paper, six sorbents with binders of different argillaceous minerals were prepared by mechanical mixing method. Desulfurization behavior for hot gas desulfurization sorbents was investigated in a fixed-bed reactor. Result showed that sorbent NTKW2 with binder of clay had a better sulfidation performance. NTKW2 had a more stable performance than other sorbents in the continuous sulfidation-regeneration cycles. Sulfur capacity of sorbent remained the same in each cycle. The desulfurization efficiency and mechanical strength of NTKW2 were the best among the tested sorbents. The behavior of NTKW2 at different temperatures showed different performances, and the best reaction temperature was 550 ℃. Higher heat stability, sulfur capacity and desulfurization efficiency were found on NTKW2 in six continuous sulfidation-regeneration cycles.     

Enabling the Li-ion conductivity of Li-metal fluorosulphates by ionic liquid grafting

Recently unveiled ‘alkali metal fluorosulphate (AMSO₄F)’ class of compounds offers promising electrochemical and transport properties. Registering conductivity value as high as 10⁻⁷ S cm⁻¹ in NaMSO₄F phases, we explored the fluorosulphate group to design novel compounds with high Li-ion conductivity suitable for solid electrolyte applications. In the process, we produced sillimanite-structured LiZnSO₄F by low temperature synthesis (T ≤ 300 °C). Examining this phase, we accidentally discovered the possibility of improving the ionic conductivity of poor conductors by forming a monolayer of ionic liquid at their particle surface. This phenomenon was studied by solid-state NMR, XPS and AC impedance spectroscopy techniques. Further, similar trends were noticed in other fluorosulphate materials like tavorite LiCoSO₄F and triplite LiMnSO₄F. With this study, we propose ‘ionic liquid grafting’ as an interfacial route to enable good Li-ion conductivity in otherwise poor conducting ceramics.