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Abstract: An attempt has been made at obtaining a catalyst for hydrogenation of ortho-chloronitrobenzene (o-CNB) to ortho-chloroaniline (o-CAN) which would be both selective and active. Ruthenium has been used as the active phase since it is the most selective of all metals investigated in the above reaction. Catalyst precursors, RuCl3·3H2O and NH4VO3, were introduced onto an unconventional support – MgF2 and reduced in hydrogen flow at 673K. The catalysts obtained revealed unusually high activity and selectivity in the reaction of hydrogenation of o-CNB to o-CAN, both in the gas- and liquid phase. The structural study of the Ru-V/MgF2 catalyst has shown that its high activity and selectivity were determined by the strong metal–support interactions and ruthenium–VO x species electron interactions. [Copyright &y& Elsevier]

The use of magnesium fluoride as a support for ruthenium has enabled to obtain a catalyst of high activity and selectivity for hydrogenation of ortho-chloronitrobenzene ( o-CNB) to ortho-chloroaniline ( o-CAN) in the liquid-phase at 353 K under 4 MPa of hydrogen pressure. The introduction of water to methanolic medium of the reaction (volume ratio of water to methanol equal to 1:2) has resulted in almost fivefold increase in catalytic activity, while selectivity towards o-CAN remained on the level close to 100%. The nature of ruthenium precursor and catalyst activation conditions appeared to have a clear influence on metallic phase dispersion that was reflected by the activity of Ru/MgF2 catalysts. The catalysts of poorer dispersion were more active in o-CNB hydrogenation, however, their selectivity to o-CAN was slight lower. [ABSTRACT FROM AUTHOR]

Abstract: Spherical monodispersed magnesium fluoride has been obtained using the microwave-assisted precipitation technique from magnesium nitrate and ammonium fluoride solutions. Studies aimed at optimizing synthesis conditions from the point of view of preparing spherical MgF2 particles of possibly high monodispersity were performed. Spherical MgF2 particles of 0.25–0.36μm in diameter have been obtained with relative standard deviation from the average value ranging from 7 to 15%. It has been established that a certain optimal range of Mg(NO3)2 and NH4F concentrations exists that enables a highly monodispersed MgF2 to be prepared. The range is narrow (0.01–0.03moldm−3) for both precursors. Spherical MgF2 particles have been characterized by SEM, XRD, DTG/DTA and FTIR techniques. [Copyright &y& Elsevier]

This study proposes, for the first time, the development of an analytical method using the new sorbent - magnesium fluoride (MgF 2) and ultrasound-assisted dispersive micro solid-phase extraction (UA DMSPE) for accurate preconcentration and isolation of sulphur in food samples. The further determination was conducted with high-resolution continuum source electrothermal molecular absorption spectrometry (HR-CS ET MAS). The main UA DMSPE parameters were investigated. Satisfying extraction efficiencies were obtained using 10 mL of sample solution, 20 mg of MgF 2 and 20 s extraction time. The limit of detection and the preconcentration factor were 0.001 μg mL−1 and 18, respectively, and no matrix effect was observed. The relative standard deviation (RSD) was 2–13%. The proposed method was applied, inter alia, to corn flakes and flour, dried raisins and goji berries as well as different types of tea leaves. The accuracy of the developed method was evaluated by analysis of certified reference materials: mixed polish herbs (INCT-MPH-2), soya bean flour (INCT-SBF-4), tea leaves (INCT-TL-1), wheat (NCS ZC73009) and corn (NCS ZC73010). Sulphur concentrations determined in these materials were in satisfactory agreement with the certified values (recoveries in the range of 94% to 101%). [Display omitted] • Ultrasound-assisted dispersive micro solid-phase extraction was used. • MgF 2 was used as an adsorbent to extract sulphur. • Recoveries of 95–101% were obtained in 5 min. • The procedure was successfully used for complex matrix samples. [ABSTRACT FROM AUTHOR]

Abstract: The MgF2–MgO system with different compositions is tested as a potential support of nickel oxide catalysts in the NO+C3H6 +O2 reaction as a function of the MgF2/MgO ratio in the support and the reaction conditions. The study was performed at temperatures ranging from 250 to 475°C in the reducing, oxidizing and stoichiometric conditions. The activity of NiO/MgF2–MgO catalysts was compared to those of NiO/MgF2, NiO/MgO, NiO/Al2O3 and NiO/SiO2. The highest activities were obtained for the catalysts supported on pure MgF2, especially in the reducing conditions. Mixed system MgF2–MgO gave a support on which nickel revealed much higher activities in NO reduction both in reducing and in oxidizing conditions when compared to NiO/MgO catalyst. [Copyright &y& Elsevier]

The effect of the presence of steam on the catalytic activity of MgF2 supported binary copper and manganese oxides in the reaction of NO+C3H6+O2 has been investigated in comparison to that on the activity of single metal systems such as Cu–O/MgF2 and Mn–O/MgF2. The reaction was performed for different compositions of the reaction mixture, i.e. under reducing, stoichiometric and oxidising conditions. The most resistant to steam proved to be the mixed Cu–Mn–O/MgF2 system, with a high conversion of NO to N2. When the inflow of steam was stopped, the catalyst underwent regeneration. [Copyright &y& Elsevier]