Boris V. Romanovsky

An approach to heterometallic alkoxide-β-diketonate complexes with a M4O4 cubane-like core and new prospects of their application in preparation of solid catalysts. X-ray single crystal study of (Co,Ni)4(acac)4(μ3-OMe)4(MeOH)4, Co2Ni2(acac)4(μ3-OMe)4(OAc)2 and Mg4(acac)4(μ3-OMe)4(MeOH)4

Abstract The interaction of the individual M4(acac)4(μ3-OMe)4(MeOH)4 complexes, M=Co, Ni in toluene/methanol media provided crystals of (Co,Ni)4(acac)4(μ3-OMe)4(MeOH)4 (I) — the product of co-crystallization of isomorphous products. The oxidation of a MeOH solution of I in air in the presence of NaOAc and aminoalcohols as catalysts gave Co2Ni2(acac)4(μ3-OMe)4(OAc)2 (II), an individual heterometallic derivative. The interaction of Mg(OCH(CH3)CH2NMe2)2 with Cu(acac)2 in toluene/methanol media produced Mg4(acac)4(μ3-OMe)4(MeOH)4 (III) as the only isolatable product. The starting Co and Ni homometallic complexes as well as the heterometallic CoNi complex II were used to prepare the zeolite-supported oxide catalysts which exhibited extremely high activity towards methanol oxidation.

Synthetic strategy for Fe-MCM-41 catalyst: a key factor for homogeneous or heterogeneous phenol oxidation

Iron(III) was introduced into the mesoporous molecular sieve MCM-41 using two protocols: (i) iron nitrate was added in situ in the course of MCM-41 synthesis; (ii) a nitrate or triiron oxoacetate complex was loaded into the as-synthesized MCM-41 sieve by using incipient wetness impregnation method. In both cases the iron content was in the range of 1–11 wt%. The prepared materials were characterized by N2-BET, XRD, H2-TPR, NH3-TPD, ESR and Mossbauer spectroscopy techniques. All the catalysts were found to exhibit high enough activity in the liquid phase oxidation of phenol by hydrogen peroxide. At 25 °C the oxidation of phenol occurs in homogeneous phase and is mediated only by the Fe3+ ions leached from the solid, while at 80 °C the framework iron atoms mainly contribute into the total activity so that the mechanism of true heterogeneous catalysis is operative. For iron content of 0.25 wt% and less, the framework iron is fairly stable and highly resistant to the acidic conditions of liquid-phase reactions.

Lanthanum cobaltite perovskite supported onto mesoporous zirconium dioxide: Nature of active sites of VOC oxidation

Novel catalytic nano-sized materials based on LaCoO(x) perovskite nanoparticles incapsulated in the mesoporous matrix of zirconia were prepared, characterized by physicochemical methods and tested in complete methanol oxidation. LaCoO(x) nanoparticles were prepared inside the mesopores of ZrO(2) by decomposition of bimetallic La-Co glycine precursor complexes. The catalysts have been studied by diffuse-reflectance FTIR-spectroscopy using such probe molecules as CO, CD(3)CN and CDCl(3) to test low-coordinated metal ions. At low temperatures of decomposition of complexes (up to 400°C), low-coordinated Co(3+) ions predominate in the LaCoO(x) nanoparticles, whereas basically Co(2+) ions are found upon increasing the decomposition temperature to 600°C. The novel nano-sized perovskite catalysts exhibit a very high catalytic activity in the abatement of volatile organic compounds present in air, like methanol and light hydrocarbons.

Selective benzene isopropylation over Fe-containing zeolite beta

Ferrisilicate analogs of zeolite beta have been investigated as catalysts for benzene isopropylation. Activity, selectivity, reaction kinetics and catalyst deactivation have been examined. Results have been compared with those obtained over Al-beta catalysts. Mixed Fe-Al-beta catalysts showed remarkably high activity and selectivity to cumene and diisopropylbenzene.

Benzene alkylation with propylene over Ga, B and Al pentasils

Summary Benzene alkylation with propylene using Ga-, B- and Al-containing pentasil zeolites as catalysts was studied. Ga-zeolites were found to be more selective towards cumene formation than Al-zeolites, the overall activities being similar. The activity of Ga-containing catalysts increases with gallium content for zeolites having the concentration up to 0.5 atom of Ga per unit cell; at higher Ga-concentration it remained almost constant. Framework boron appeared to have no effect on the activity of MFI-catalysts.

New Preparation Method Of Ox-Red Catalysts Via Topological Heterogenization Of Metallocomplexes

Abstract New synthetic way for zeolite-included metal phthalocyanines using preadsorbed bis-cyclopentadienyl as well as bi- and trinuclear carbonyl complexes of Ni, Ru, Fe, Co and Os as precursors is reported. The zeolite-included complexes were characterized by ES, FT-IR and XPS techniques. The formation of phthalocyanine complexes in zeolite matrix can proceed to completion. The molecules of PcM are distiributed rather homogeneously through the matrix bulk, the PcMs being localized inside the zeolite large cages. Bivalent state for the included Fe, Co and Ni complexes was found while the Ru and Os phthalocyanines seem to contain trivalent metals. Nitrogen oxides can be reduced by both carbon monoxide and molecular hydrogen at 200–300°C using the zeolite inclusion PcMs as catalysts. Their catalytic activity depends on central atom nature, its valency and coordination state.

Modification of MCM-41 and SBA-15 mesoporous silicas by imidazolium ionic liquids

MCM-41 and SBA-15 mesoporous molecular sieves are modified with imidazolium ionic liquid (IL) via both physical adsorption and covalent grafting. The considerable effect of IL grafting on the porous structure and the particle morphology of mesoporous supports is shown. The pore size of these supports is found to be a key parameter determining the possibility of loading IL into such support materials.

Iron(III) chloride supported on MCM-41 molecular sieve as a catalyst for the liquid-phase oxidation of phenol

FeCl3 was supported on MCM-41 mesoporous molecular sieve via adsorption or coordination bonding and by embedding as an anionic constituent of covalently immobilized imidazolium ionic liquid (IL). The synthesized materials were characterized by N2-BET, SEM, TEM, FT-IR, 1H, 13C, and 29Si NMR, and DSC-TG. All of the catalysts were shown to be active for the liquid-phase oxidation of phenol by hydrogen peroxide. Supported FeCl3 species present as tetrachloroferrate counterions of immobilized IL are the most resistant to iron leaching.

Mesoporous MgO: Synthesis, physico-chemical, and catalytic properties

Mesoporous MgO was obtained via the hydrothermal synthesis using both ionogenic and non-ionogenic surfactants as structure-directing templates. The materials prepared were characterized by SEM, BET-N2, XRD, and TG-DTA techniques. MgO particles are spherical 20-μm aggregates of primary oxide particles well shaped as rectangular parallelepipeds. Magnesium oxide samples have the specific surface area of 290–400 m2/g and pore sizes of 3.3–4.1 nm. Their mesoporous structure remained unchanged after calcination up to 350°C. Catalytic activity of mesoporous MgO was studied in acetone condensation reaction.

Molecular catalyst design. Synthesis, characterization and properties of zeolite NaY catalysts made with a tetranuclear copper(II) complex

Abstract Highly active oxidation catalysts have been made by treating dehydrated zeolite NaY with excesses of the neutral tetranuclear copper(II) precursor (μ4-O)L4Cu4Cl6 (A, L = N,N-diethylnicotinamide) in methylene chloride, followed by methylene chloride washing, drying and oxidation with O2 at 220°C. The loaded samples contain from 3.4 to 14.3% w/w total copper, depending on the amount of A used. Previous measurements with a different ‘titration’ loading method together with analytical and spectroscopic data for materials loaded with different excesses of A indicate 2.9–13.8% w/w copper on the zeolite surface (50 m2/g) due to a zeolite-solution equilibrium with A. Oxidation of the most heavily loaded sample with O2 gives a catalyst that is ten times more active per gram for CO oxidation than bulk CuO at 450°C. The most lightly loaded sample oxidizes CO 115 times faster than bulk CuO on a per gram CuO basis. Turnover numbers at infinitely dilute CuO loading approach 75% of the TON for bulk CuO, suggesting that CO oxidation on bulk CuO involves more than one CuO site. Prospects for catalyst development through transmetallation chemistry and different loading methods are discussed.