Karakhanov Eduard A

Bio: Karakhanov Eduard A is an academic researcher from Moscow State University. The author has contributed to research in topics: Catalysis & Mesoporous material. The author has an hindex of 21, co-authored 210 publications receiving 1607 citations. Previous affiliations of Karakhanov Eduard A include Russian Academy of Sciences & Gubkin Russian State University of Oil and Gas.

Mesoporous Metal Catalysts Templated on Clay Nanotubes

Abstract: Halloysite is a natural tubular aluminosilicate clay of ca. 50 nm diameter and 0.5–1.5 micrometers in length. The nanoarchitectural modification of halloysite inner/outer surfaces can be achieved t...

Core/Shell Ruthenium–Halloysite Nanocatalysts for Hydrogenation of Phenol

Abstract: Halloysite tubular nanoclay was applied as a template for synthesis of ruthenium core–shell composite catalysts for the first time; 50 nm diameter ceramic tubular systems with metal seeded interiors were produced. The procedure for the metal deposition and prior halloysite modification had a significant influence on properties of the catalyst and, as a consequence, on its activity in hydrogenation of phenol. Cyclohexanol was the main reaction product, but its yield depended on the substrate conversion and nanoarchitectural composition of the catalysts used. The maximum catalytic activity (turnover frequency, TOF) achieved was 17 282 h–1 in terms of hydrogen uptake per surface Ru atoms. The substrate selectivity of halloysite-based catalysts was also demonstrated at the comparative hydrogenation of phenol and various cresols.

Hydrodeoxygenation of guaiacol as a model compound of bio-oil in methanol over mesoporous noble metal catalysts

Abstract: The liquid phase hydrodeoxygenation (HDO) of guaiacol (GUA), a model compound of bio-oil, was studied on bimetallic (PtPd) and monometallic (Ru) catalysts supported on mesoporous aluminosilicate of Al-HMS(X) type with different Si/Al (X) ratios and on mesoporous zirconia modified with silica (m-ZrO2-SiO2) in the presence of methanol as a solvent. The catalysts were characterized by NH3-TPD, TEM, XPS, 27Al and 29Si solid-state NMR and N2 adsorption–desorption methods. The influence of сatalyst loading, temperature, solvent/guaiacol ratio and contact time on the catalytic performance was investigated. It was established that, decreasing the Si/Al ratio and, correspondingly, increasing the acidity of the catalysts based on Al-HMS led to increasing conversion of guaiacol. Phenol, catechol, and their methylated derivatives were the main products of guaiacol HDO reaction in methanol at low catalyst loading (guaiacol/metal ratio, 800). It was found that the fraction of completely hydrodeoxygenated products (cyclohexane and methylcyclohexane) greatly increased as the catalyst loading grew (guaiacol/metal ratio, 160). Conversion of guaiacol on PtPd/m-ZrO2-SiO2 catalyst was higher than that on PtPd/Al-HMS(10), in accordance with the larger number of acid sites on the catalyst surface; however, the undesirable heavy fraction of methylated by-products was also higher. Ru-based catalysts exhibited the highest catalytic activity and showed unusually high selectivity toward fully hydrodeoxygenated products (cyclohexane, methylcyclohexane) in the HDO of guaiacol in the presence of methanol. Guaiacol can be efficiently converted into alkanes, with quantitative conversion and selectivity to cyclohexanes of 78% over Ru/Al-HMS(10) catalyst under relatively mild conditions (200 °C, 5 MPa H2). Methylation under the influence of methanol, deoxygenation on acid sites and aromatic ring hydrogenation on metal sites proceeded in a parallel way according to the suggested reaction pathways.

Functional supramolecular systems: design and applications

Abstract: The interest in functional supramolecular systems for the design of innovative materials and technologies, able to fundamentally change the world, is growing at a high pace. The huge array of publications that appeared in recent years in the global literature calls for systematization of the structural trends inherent in the formation of these systems revealed at different molecular platforms and practically useful properties they exhibit. The attention is concentrated on the topics related to functional supramolecular systems that are actively explored in institutes and universities of Russia in the last 10–15 years, such as the chemistry of host–guest complexes, crystal engineering, self-assembly and self-organization in solutions and at interfaces, biomimetics and molecular machines and devices. The bibliography includes 1714 references.

Oxidative Desulfurization of Fuels Using Heterogeneous Catalysts Based on MCM-41

Abstract: Mesoporous silicas of MCM-41 type modified by transition metal oxides, such as molybdenum, vanadium, and tungsten, were synthesized These materials were characterized by low-temperature nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, X-ray spectral fluorescence analysis, and transmission electron microscopy techniques and applied for the removal of sulfur compounds in model and real fuels by oxidative desulfurization The catalysts obtained were tested under optimal conditions Dibenzothiophene was removed completely, and sulfur removal in gasoline and diesel fractions could reach 91 and 63%, respectively These catalysts retain their activity in gasoline fraction desulfurization for 5 cycles

Activation of c-h bonds by metal complexes

Abstract: ion. The oxidative addition mechanism was originally proposed22i because of the lack of a strong rate dependence on polar factors and on the acidity of the medium. Later, however, the electrophilic substitution mechanism also was proposed. Recently, the oxidative addition mechanism was confirmed by investigations into the decomposition and protonolysis of alkylplatinum complexes, which are the reverse of alkane activation. There are two routes which operate in the decomposition of the dimethylplatinum(IV) complex Cs2Pt(CH3)2Cl4. The first route leads to chloride-induced reductive elimination and produces methyl chloride and methane. The second route leads to the formation of ethane. There is strong kinetic evidence that the ethane is produced by the decomposition of an ethylhydridoplatinum(IV) complex formed from the initial dimethylplatinum(IV) complex. In D2O-DCl, the ethane which is formed contains several D atoms and has practically the same multiple exchange parameter and distribution as does an ethane which has undergone platinum(II)-catalyzed H-D exchange with D2O. Moreover, ethyl chloride is formed competitively with H-D exchange in the presence of platinum(IV). From the principle of microscopic reversibility it follows that the same ethylhydridoplatinum(IV) complex is the intermediate in the reaction of ethane with platinum(II). Important results were obtained by Labinger and Bercaw62c in the investigation of the protonolysis mechanism of several alkylplatinum(II) complexes at low temperatures. These reactions are important because they could model the microscopic reverse of C-H activation by platinum(II) complexes. Alkylhydridoplatinum(IV) complexes were observed as intermediates in certain cases, such as when the complex (tmeda)Pt(CH2Ph)Cl or (tmeda)PtMe2 (tmeda ) N,N,N′,N′-tetramethylenediamine) was treated with HCl in CD2Cl2 or CD3OD, respectively. In some cases H-D exchange took place between the methyl groups on platinum and the, CD3OD prior to methane loss. On the basis of the kinetic results, a common mechanism was proposed to operate in all the reactions: (1) protonation of Pt(II) to generate an alkylhydridoplatinum(IV) intermediate, (2) dissociation of solvent or chloride to generate a cationic, fivecoordinate platinum(IV) species, (3) reductive C-H bond formation, producing a platinum(II) alkane σ-complex, and (4) loss of the alkane either through an associative or dissociative substitution pathway. These results implicate the presence of both alkane σ-complexes and alkylhydridoplatinum(IV) complexes as intermediates in the Pt(II)-induced C-H activation reactions. Thus, the first step in the alkane activation reaction is formation of a σ-complex with the alkane, which then undergoes oxidative addition to produce an alkylhydrido complex. Reversible interconversion of these intermediates, together with reversible deprotonation of the alkylhydridoplatinum(IV) complexes, leads to multiple H-D exchange