F. K. Schmidt
Irkutsk State University
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Featured researches published by F. K. Schmidt.
Kinetics and Catalysis | 2010
N. I. Skripov; L. B. Belykh; L. N. Belonogova; V. A. Umanets; E. N. Ryzhkovich; F. K. Schmidt
The effect of the nature of the acido ligand in the precursor and the modifying action of elemental phosphorus on palladium catalysts for hydrogenation are reported. The large turnover frequency (TOF) and turnover number (TON) values observed for styrene hydrogenation on the Pd blacks prepared in situ by PdCl2 reduction with hydrogen in DMF are due to the formation of fine-particle catalyst with a base particle size of 6–10 nm. This is explained by the high PdCl2 reduction rate and by the formation of a palladium cluster stabilizer—dimethylammonium chloride—in the reaction system via the catalytic hydrolysis of the solvent (DMF). The modifying action of elemental phosphorus on the properties of the palladium catalysts depends on the nature of the acido ligand in the precursor. In the case of oxygen-containing precursors at small P/Pd ratios, elemental phosphorus exerts a promoting effect, raising the TON and TOF values by a factor of about 9. In the case of palladium dichloride as the precursor, white phosphorus exerts an inhibiting effect. At the same time, it enhances the stability of the catalyst, raising the TON value at P/Pd = 0.3. The causes of these distinctions are considered.
Kinetics and Catalysis | 2010
L. B. Belykh; N. I. Skripov; L. N. Belonogova; V. A. Umanets; F. K. Schmidt
The applicability of elemental phosphorus as a modifier of palladium catalysts for hydrogenation was demonstrated, and the conditions for the synthesis of nanoparticles that are highly efficient in hydrogenation catalysis were optimized. The modifying effect of elemental phosphorus depends on the P/Pd ratio; it is associated with changes in the catalyst dispersity and the nature of the formed nanoparticles containing various palladium phosphides (PdP2, Pd5P2, and Pd6P) and Pd(0) clusters. The main stages of the formation of palladium catalysts for hydrogenation were determined, and a model of an active catalyst, in which the Pd6P phosphide is the core of a nanoparticle and Pd(0) clusters form a shell, was proposed.
Kinetics and Catalysis | 2011
L. B. Belykh; N. I. Skripov; L. N. Belonogova; V. A. Umanets; T. P. Stepanova; F. K. Schmidt
The catalytic properties and nature of the nanoparticles forming in the system based on Pd(dba)2 and white phosphorus are reported. A schematic mechanism is suggested for the formation of nanosized palladium-based hydrogenation catalysts. The mechanism includes the formation of palladium nanoclusters via the interaction of Pd(dba)2 with the solvent (N,N-dimethylformamide) and substrate and the formation of palladium phosphide nanoparticles. The inhibiting effect exerted by elemental phosphorus on the catalytic process is due to the conversion of part of the Pd(0) into palladium phosphides, which are inactive in hydrogenation under mild conditions, and the formation of mainly segregated palladium nanoclusters and palladium phosphide nanoparticles. By investigating the interaction between Pd(dba)2 and white phosphorus in benzene, it has been established that the formation of palladium phosphides under mild conditions consists of the following consecutive steps: Pd(0) → PdP2 → Pd5P2 → Pd3P. It is explained why white phosphorus can produce diametrically opposite effects of on the catalytic properties of nanosized palladium-based hydrogenation catalysts, depending on the nature of the palladium precursor.
Russian Journal of General Chemistry | 2013
L. B. Belykh; N. I. Skripov; V. V. Akimov; V. L. Tauson; T. P. Stepanova; F. K. Schmidt
The size, nature, and surface state of nanoparticles formed by reduction of Pd(acac)2 with hydrogen in the presence of P4 have been elucidated by means of X-ray photoelectron spectroscopy, X-ray powder diffraction analysis, and transmission electron microscopy. The nanoparticles (average diameter of 5.6 nm) consist of Pd6P and palladium nanoclusters (at initial ratio P/Pd = 0.3). Dimethylammonium dihydro- and hydrophosphates are found in the surface layer of the catalyst nanoparticles. The nanoparticles are stabilized by ammonium salts formed via dimethylformamide hydrolysis.
Kinetics and Catalysis | 2003
F. K. Schmidt; L. B. Belykh; T. V. Goremyka
Findings on the formation and features of nanosized particles based on palladium complexes, which are active in hydrogenation catalysis, are summarized. Depending on the nature of a reducing agent, nanosized particles formed by the reduction of palladium(II) phosphine complexes are either metallic nuclei stabilized by organophosphorus ligands or associates of polynuclear phosphido or phosphinideno palladium complexes whose surface contains immobilized Pd(0) clusters. The ensembles of the Pd(0) atoms are active in hydrogenation.
Russian Journal of Applied Chemistry | 2015
N. I. Skripov; L. B. Belykh; T. P. Sterenchuk; F. K. Schmidt
Fundamental aspects of the influence of solvent nature on the activity and selectivity of palladium catalysts modified with white phosphorus in hydrogenation of ortho-chloronitrobenzene were determined. The conditions are suggested in which the chemoselectivity of palladium catalysts modified with white phosphorus can be raised to 93–95% with respect to ortho-chloroaniline in the temperature range 30–80°C without accumulation in the reaction system of undesirable products, ortho-chlorophenylhydroxylamine and azo- and azoxychlorobenzene.
Russian Journal of General Chemistry | 2012
F. K. Schmidt; Yu. Yu. Titova; L. B. Belykh; V. A. Umanets; Spartak S. Khutsishvili
The interaction of Co(acac)2(3) with LiAlH4 or LiAlH(t-BuO)3 was studied using NMR, UV, IR, ESR spectroscopy, electron microscopy, and volumometry. The basic stages of formation of cobalt catalysts for hydrogenation were suggested. The formation of the nanoparticles that are active in the hydrogenation process is shown to occur at a ratio of reagents 5 ≤ Red/Co ≤ 12. The nanoparticles are stabilized by an excess of LiAlH4 or LiAlH(t-BuO)3, as well as by the products of their catalytic decomposition under the action of cobalt in the reduced state. At the ratio LiAlH4 / Co> 12 to obtain the particles active in catalysis their activation by a proton-donor compound is required.
Russian Journal of General Chemistry | 2016
L. B. Belykh; N. I. Skripov; T. P. Sterenchuk; V. V. Akimov; V. L. Tauson; F. K. Schmidt
Phase composition and surface layer state of the Pd–P hydrogenation catalyst formed at various P/Pd ratios from Pd(acac)2 and white phosphorus in a hydrogen atmosphere were determined. Palladium on the catalyst surface is mainly in two chemical states: as Pd(0) clusters and as palladium phosphides. As the P/Pd ratio increases, the fraction and size of palladium clusters decrease, and also the phase composition of formed palladium phosphides changes: Pd3P0.8 → Pd5P2 → PdP2. The causes of the modifying action of phosphorus on the properties of palladium catalysts for hydrogenation of unsaturated compounds were considered.
Low Temperature Physics | 2015
Yu. Yu. Titova; L. B. Belykh; F. K. Schmidt
EPR spectroscopy is used to study catalytic hydration and polymerization reaction systems based on α-diimine complexes of Ni(0) and Ni(II) with the general formula NiBr2(DAD–R) (R = –C3H7 or –CH3) or Ni(DAD–CH3)2 (DAD(–C3H7) = 1,4-bis(2,6-diiso-propylphenyl)-2,3-(dimethyl-1,4-diazabuta-1,3-diene, DAD(–CH3) = 1,4-bis(2,6-dimethylphenyl)-2,3-dimethyl-1,4-diazabuta-1,3-diene)), in combination with Lewis acids (AlEt3, AlEt2Cl, AlEtCl2, B(F5C6)3, BF3·OEt2). Ni(I) complexes of the form (DAD–R)NiX2AlX′y(C2H5)3–y composition (an aluminum atom can be replaced by a boron atom) were identified, where R = –CH3 or –C3H7, X = Br, and X′ = Cl or –C2H5 and α-diimine anion radicals are included in derivatives of aluminum or boron. Oxidation reactions of the Ni(DAD–CH3)2 complex with aluminum alkyl halides and boron derivatives with formation of paramagnetic nickel complexes are observed. It is found that there is no direct relationship between the polymerization activity of ethylene or hydration of the alkenes and the con...
Kinetics and Catalysis | 2014
Yu. Yu. Titova; L. B. Belykh; A. V. Rokhin; O. G. Soroka; F. K. Schmidt
The catalytic characteristics of the individual complex Ni(PPh3)2(C2H4) and Ni(PPh3)nCl (n = 2 or 3) and those of systems based on these complexes in combination with Brönsted and Lewis acids in ethylene and propylene oligomerization have been determined. A correlation between the BF3 · OEt2 solution storage time and the catalytic properties of the nickel systems has been established for the reactions of the lower alkenes. The observed increase in the turnover frequency and turnover number of the catalyst is due to the increase in the Brörsted acid concentration as a result of irreversible conversions of BF3 · OEt2 caused by its interaction with impurity water in the solvent. The formation of the Ni(PPh3)2(C2H4)-BF3 · OEt2 catalytic system in the presence of a substrate dramatically extends the system’s service life. The interaction of the nickel precursors with boron trifluoride etherate has been investigated using a complex of physical methods, and the main reactions yielding catalytically active species have been revealed.