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The use of magnesium fluoride support for ruthenium active phase allowed obtaining new catalysts of high activities in the hydrogenation of toluene and ortho-chloronitrobenzene. Ruthenium colloid catalysts (1 wt.% of Ru) were prepared by impregnation of the support with the earlier produced polyvinylpyrrolidone (PVP)-stabilized ruthenium colloids. The performances of the colloidal catalysts and those obtained by traditional impregnation were tested in the reactions of toluene hydrogenation to methylcyclohexane and selective hydrogenation of ortho-chloronitrobenzene (o-CNB) to ortho-chloroaniline (o-CAN). It was shown that the use of chemical reduction method allows obtaining highly monodisperse ruthenium nanoparticles of 1.6-2.6 nm in size. After reduction in hydrogen at 400oC, the colloidal ruthenium nanoparticles were found to strongly interact with MgF2 surface (SMSI), which decreased the catalyst ability to hydrogen chemisorption, but despite this, the colloid catalysts showed higher activity in o-CNB hydrogenation and higher selectivity to o-CAN than the traditional ones. It is supposed that their higher activity can be a result of high dispersion of Ru in colloid catalysts and the higher selectivity can be a consequence of the lower availability of hydrogen on the surface. [ABSTRACT FROM AUTHOR]

Novel magnesium oxo-fluoride supports containing different amounts of MgO, prepared by the sol–gel method have been proposed for the synthesis of gold catalysts. The MgF2–MgO supports have mesoporous structure and their surface area is a few times larger than those of pure MgF2 or pure MgO. Gold catalysts have been prepared by impregnation of the MgF2–MgO supports with HAuCl4 in the amount corresponding to 1 wt.% Au. The gold catalysts has been characterized by XRD, TEM measurements and the catalytic activity in CO oxidation at temperatures 30–300 °C have been performed. The Au/MgF2–MgO catalysts show higher activities (depending on the content of MgO in the support) as compared to Au/MgF2 and Au/MgO prepared under the same conditions. Their activities fall into the upper range of gold catalysts supported on other carrier reported in literature. [ABSTRACT FROM AUTHOR]

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]

The paper presents results of studies on the structure of MgF2 support, performed using various experimental methods such as XRD, IR, temperature programmed techniques and low temperature nitrogen adsorption. MgF2 is characterized by an XRD spectrum with over 40 patterns, which enabled us to follow the changes in crystallite size and internal tension caused by the thermal treatment. TPE H2O and TG allowed an estimation of the surface OH groups concentration as ∼3–4 nm-2. [ABSTRACT FROM AUTHOR]

The modification of commercial silica with solutions of NH4F or NH4Cl salts, followed by thermal treatment, enabled generation of the acidic sites in SiO2 and changed its textural properties. The use of ammonium salts solution also caused the generation of additional porosity. Using NH4F solution caused significant decrease in the specific surface area and the increase in the average pore diameter. The number and strength of resulting acid sites depend on the nature of anion in the applied ammonium salt and the concentration of salt solution. It has been found that the sample treated with NH4F presented higher total acidity (TPD–NH3) and the amount as well as the strength of acid sites increased with the concentration of the used modifier. As modified amorphous SiO2 materials used as a support for iridium (1 wt %, Ir(acac)3) nanoparticles permitted to obtain highly active catalysts for toluene hydrogenation under atmospheric pressure. The highest activity (expressed as the apparent rate and TOF) was obtained for iridium catalysts supported on silica modified by NH4F with the highest acidity. The modification of silica with NH4F favors the generation of centers able to adsorb toluene, which results in higher activity of this catalyst. [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]

Abstract: A combination of iridium catalytic phase and a new MgF2–MgO support, obtained by the sol–gel method, has been shown to be an active catalyst for CO oxidation reaction. A series of catalysts containing 1wt.% Ir were obtained by impregnation of MgF2–MgO and pure MgF2 or MgO supports with different precursors, i.e. H2IrCl6, Ir(acac)3 and Ir4(CO)12. The surface areas and pore size distributions of the catalysts obtained were determined by the BET and BJH methods, respectively. Dispersion of iridium and the mean size of the crystallites were evaluated on the basis of hydrogen chemisorption. The activity of the catalysts in the CO oxidation reaction was measured. The effect of MgO content in the support and the influence of iridium precursor on the structure and activity of the iridium catalysts in the CO oxidation reaction were studied. The results show that the use of MgF2–MgO support with 60mol % content of MgO and the use of Ir(acac)3 precursor lead to the catalyst with high surface area, high iridium dispersion and the best catalytic performance in CO oxidation. [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]

Abstract: The monooxides copper, manganese, molybdenum and chromium catalysts supported on MgF2 were tested in NO decomposition and reduction by propene. The effect of the oxides content, time on stream and O2 concentration in reaction mixture during NO reduction on their catalytic activity was investigated. All the catalysts showed the optimum active phase concentration corresponding to 2–4wt.% of the metal. For the best copper catalyst an effect of introduction of another oxide (manganese or chromium oxide) on the catalytic performance was studied. The double copper-manganese oxide sample containing 2wt.% Cu and 4wt.% Mn was proved to ensure the best catalytic performance. [Copyright &y& Elsevier]

The oxide system TiO 2 -SiO 2 as well as a TiO 2 -SiO 2 /lignin system have been obtained by the sol-gel synthesis method and applied as supports in Supported Ionic Liquid Phase (SILP) materials. In total 24 SILP systems were obtained with ionic liquids containing imidazolium, pyridinium, phosphonium or sulfonic cations and bis(trifluoromethylsulfonyl)imide or methylsulfate anions, and homogeneous complexes of rhodium or platinum as the active phase. The supports and catalytic materials were subjected to thorough characterization by elemental analysis, XRD, SEM-EDX, IR, and TGA, and their particle size distribution and porous properties were assessed. The new SILP materials were used in hydrosilylation of 1-octene with 1,1,1,3,5,5,5-heptamethyltrisiloxane. The effectiveness of hydrosilylation reaction catalyzed by the obtained SILP materials for the polar and nonpolar reagents was assessed. All the catalytically active materials were proved to be easy to isolate and reuse, and the best SILP systems have been shown to be active in 10 or more subsequent catalytic cycles., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Research was carried out on the incorporation of divalent cobalt cations into the crystalline structure of MgF 2 to form Mg x Co 1- x F 2 binary fluorides, which had not been investigated before. The above fluorides were obtained by the precipitation from aqueous solution of magnesium and cobalt nitrates with ammonium fluoride. Binary fluorides containing 0.6, 7.5 and 37.7 mol% CoF 2 were prepared. The effects of treatment temperature (300, 400 °C) and atmosphere (oxidizing or reducing) on the structure (XRD, TPR-H 2 , UV-Vis), texture (low-temperature N 2 adsorption), surface composition (XPS) and surface acidity (NH 3 -TPD) of the binary fluorides were determined. It has been found that in Mg x Co 1- x F 2 an isomorphic substitution occurs of Mg 2+ cations by Co 2+ cations which results in the formation of a rutile-type solid solution. The obtained binary fluorides are characterized by a mesoporous structure and relatively large surface area. It has been found that thermal treatment of the binary fluorides in oxidizing conditions results in the oxidation of CoF 2 to Co 3 O 4 even at 300 °C; therefore it is not possible to obtain pure Mg x Co 1- x F 2 binary fluorides in the presence of air. The preparation of the latter requires reducing conditions, namely thermal treatment of dry precipitate at 300 °C in an atmosphere of hydrogen. If the treatment is conducted at a higher temperature (400 °C), CoF 2 undergoes a partial reduction to metallic cobalt. An XPS study has shown the presence of hydroxyl groups in the investigated samples. However, these are solely surface groups because their presence was not detected by XRD measurements. The binary fluorides obtained by our method are characterized by a very narrow optical energy gap (5.31-3.50 eV), considerably narrower than that recorded for bulk fluorides. Measurements of temperature-programmed desorption of ammonia have shown that the incorporation of cobalt cations into the crystal structure of MgF 2 results in a decrease in the surface acidity of the binary fluorides., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)