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Catalytic reduction of NO by CO over Pd - doped Perovskite-type catalysts

100%
Khristova M., Petrović S., Terlecki-Baričević A., Mehandjiev D.
Open Chemistry
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2009
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vol. 7
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issue 4
857-863
EN
The perovskite type oxides (nominal formula LaTi0.5Mg0.5O3) with addition of Pd were prepared by annealing the ethanol solution of precursors in nitrogen flow at 1200°C and characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption of NO (NO-TPD). Their activity was evaluated for NO reduction by CO under stoichiometric and oxidizing conditions and for direct decomposition of NO. Pd substituted samples exhibited high NO reduction activity and selectivity towards N2. Nearly complete elimination of NO was achieved at 200°C. Two simultaneous reactions, NO reduction by CO and direct decomposition of NO as well as two forms of NO adsorption were observed on the surface of Pd substituted perovskite samples. The distribution of Pd in different catalytically active sites or complexes on at the catalyst surface may be responsible for the proceeding of two reactions: NO reduction with CO and direct NO decomposition. [...]
2
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Investigation on the catalytic activity of doped low-percentage oxide catalysts Mn/ZnO obtained from oxalate precursor

100%
Donkova B., Milenova K., Mehandjiev D.
Open Chemistry
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2008
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vol. 6
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issue 1
115-124
EN
The precursors with a low manganese content ≤ 0.07% Mn were synthesized by spontaneous crystallization from Zn2+, Mn2+ and C2O42−-containing solutions. The initial ratio Zn2+:C2O42− = 1:1 and 1:2 influences the morphology and prevailing orientations of the crystallites in the oxalate samples. The presence of such small Mn content in the samples does not change the morphology or size of the crystals. The ZnO and Mn/ZnO oxides with manganese content from 0.51×10−2 to 15.1×10−2 Wt % are obtained after thermal decomposition of the oxalates. The oxides preserved the morphology of the precursors. The catalytic tests show that the pure ZnO has a poor activity for CO oxidation reaction. Its doping with Mn promotes the catalytic activity (up from twice to five times) in spite of the very low contents of the dopants. The observed increase of the activity depends on both dopant concentration and Zn2+:C2O42− ratio, probably due to the different mechanism of the manganese inclusion and different morphology of the oxides. The catalysts of the 1:2 series are more active in CO oxidation reaction. [...]
3
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Visible light photocatalytic activity of TiO2 deposited on activated carbon

76%
Eliyas A., Ljutzkanov L., Stambolova I., Blaskov V., Vassilev S., Razkazova-Velkova E., Mehandjiev D.
Open Chemistry
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2013
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vol. 11
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issue 3
464-470
EN
Abstract Four photocatalyst samples, prepared from beech sawdust, were synthesized by an original method, combining pyrolysis and impregnation - two of them: TiO2 + activated carbon and other two - only activated carbon. The pyrolysis process has been carried out at two different temperatures - 680°C and 830°C. The prepared samples were characterized by a series of methods - XRD, BET, SEM and DTA/TG. The most important result was achieving visible light photocatalytic activity with an azo dye pollutant for both materials. The TiO2/AC-680°C sample demonstrated higher activity under visible light illumination than the TiO2/AC-830°C sample. The visible light activity was attributed to the active carbon component in the composite materials, which was evidenced by the photocatalytic tests with bare carbon (without any TiO2) manifesting visible light activity. The AC-680°C carbon was superior to the AC-830°C under visible illumination probably due to its higher specific surface area and porous texture. UV-light testing of the photocatalytic activity revealed that the TiO2/AC-680°C sample was higher than that of the TiO2/AC-830°C under polychromatic UV-A illumination (320–400 nm with a maximum at l = 365 nm). The TiO2/AC-680°C sample was also more efficient with the monochromatic UV-C illumination (l = 254 nm). Graphical abstract [...]
4
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Copper(II) complexes of the antihypertensive drug nadolol

76%
Getova V., Pantcheva I., Ivanov D., Mehandjiev D., Skumryev V., Bontchev P.
Open Chemistry
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2007
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vol. 5
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issue 1
118-131
EN
The complexation of the non-selective β-blocker nadolol, HL, 1 with copper(II) leads to formation of mono-and dinuclear complexes depending mainly on the metal-to-ligand molar ratio. The mononuclear violet complex CuL2·2Solv, 2, was obtained in a soluble form at metal-to-ligand molar ratio Cu(II): HL ≤ 1: 10 in methanolic or slightly alkaline aqueous solutions. The dinuclear green complex Cu2L2Cl2·H2O, 3 was synthesized at Cu(II): HL ≥ 1: 2 molar ratio in methanolic solutions. The complexes were studied using spectral (UV-Vis, FT-IR, EPR), magnetochemical, thermogravimetric methods and elemental analysis. In the complexes nadolol acts as a monoanionic bidentate ligand coordinated to copper(II) through the NH-and the deprotonated OH-groups of its aminoalcohol fragment. [...]
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