Vol 90, No 12 (2017)

Data are presented on the modification of cracking catalysts in order to improve their resistance to the poisoning effect of nitrous compounds of various classes. The modification of the catalyst matrix consists in that special additives are introduced into the catalyst formulation to improve its resistance to the poisoning action of nitrous compounds. Acid-activated clays and mixed oxides are considered as these additives.

Effect of the calcination temperature of the MnOx/Ga2O3 system on its structural and catalytic properties in the reaction of oxidation of CO and hydrocarbons. The dependences of the catalytic activity of MnO_x/Ga₂O₃ in the reactions of CO and ethane oxidation on the calcination temperature exhibit an extremal behavior. The maximum values of activity are observed upon calcination of the system at 700°C, i.e., at the temperature that is limiting for the existence of a solid solution of manganese ions in γ-Ga₂O₃. The structural changes occurring with increasing calcination temperature are accompanied by a substantial decrease in the specific surface area of a sample. The observed rise in the specific catalytic activity (by a factor of ~7 upon an increase in the preliminary-calcination temperature from 600 to 800°C) confirms that the thermal activation effect exists for the given system.

Effect of cyclohexane and benzene on the isomerization of n-heptane on Pt/BEA-Al₂O₃ and Pt/MORAl₂O₃ catalysts was studied. In the presence of catalysts with platinum deposited from a [Pt(NH₃)₄]Cl₂ solution, cyclohexane and benzene inhibit the conversion of n-heptane. At the same time, the presence of cycloalkanes and aromatic hydrocarbons leads to an increase in the isomerization selectivity due to the suppression of side reactions of hydrocracking. Samples based on the BEA zeolite were found to be more active as compared with similar samples based on mordenite.

Tungstate-containing aluminum oxide is suitable as a catalyst support for hydrodeoxygenation of sunflower oil, ensuring 81–83 wt % yield of liquid products at 380°С, 4.0 MPa, and feed space velocity of 1 h^–1. The catalyst acidity increases with increasing tungsten oxide content, leading to an increase in the content of decarboxylation/decarbonylation products and isoparaffins in the product mixture.

The relationships of the formation of aluminum oxide from aluminum hydroxide peptized with organic acids (propionic, maleic, malonic, tartaric) were studied. The pore structure parameters of the hydroxide samples and of aluminum oxide samples obtained from them are strongly influenced by acid peptization. The nature of the acid influences the extent of defectiveness of the γ-Al₂O₃ structure, manifested in the density of aluminum oxide, measured by helium pycnometry. The possibility and conditions for preparing mesoporous γ-Al₂O₃ suitable for use in chemical and petrochemical processes were determined.

The structure and electrochemical properties (specific capacitance and electrical resistance) of various grades of carbon black before and after high-temperature gas-chemical treatment were studied. The textural and structural parameters were determined by the methods of low-temperature nitrogen adsorption, dibutyl phthalate absorption, X-ray diffraction analysis, and Raman spectroscopy. The results are compared to the characteristics of Printex XE2-B extra-conductive carbon black.

The effect of chemical treatment (with nitric acid, sodium hydroxide, or superheated steam) of sapropel carbonization products on the properties of the final carbon–mineral materials was studied. Steam activation exerts the strongest effect on the samples of carbon–mineral materials prepared from organic sapropel, leading to the maximal increase in the surface area and to a change in the textural characteristics. All kinds of treatment lead to a considerable increase in the fraction of micropores (to 26% of the total pore volume) and to a decrease in the fraction of macropores (from 44 to 14% of the total pore volume). The strongest changes in the properties of carbon–mineral materials prepared from mineral sapropel are observed upon acid treatment.

Adsorption properties of carbon sorbents modified with glycolic and lactic acid oligomers and copolymers of these toward organic dyes of varied nature: Methylene Blue and Metanil Yellow were studied. Differences in the adsorption of the dyes by the modified sorbents, due to the nature of their surface, were found.

An efficient highly diluted synthetic approach to the synthesis of 1,9-dicarbonyl-2,8-dioxo-butyne ester ferrocenophane (L) has been developed. The title compound was characterized by IR, UV, FL, 1H NMR, spectroscopies, elemental analysis and so on. Further complex L shows fluorescence responses to Co²⁺ and Cu²⁺ in CH3OH, The results indicate that the complex could be applied in multianayte detection. The binding ability of receptor L CH3OH was tested for various cations (Co²⁺, Cu²⁺, Zn²⁺, and Ni²⁺ in water) and the binding constants for Co²⁺ and Cu²⁺ were the computed, having a distinct absorbance shift. The receptor is a very attractive array because its distinct absorbance shift profile in a semi-aqueous phase, making it applicable in the area of biology, environmental sciences and material chemistry.

Conductive hierarchically porous LiFePO₄ blocks enhanced by carbon fiber were successfully obtained, which is benefited from nice sinter-activity of hydrothermal synthesized LiFePO₄. In combination with hierarchically porous and carbon-fiber-reinforced electric-conductive topologies, metal-current-collector- and binder-free design, the as-prepared bulk electrodes present excellent rate capability and cycle life. Our proofof- concept study on LiFePO₄-based bulk electrodes shows facile approach to improve energy density and lower cost of Li-ion batteries.

Electrodeposited PdNi and Pd samples were tested for methanol and ethanol oxidation reaction (MOR and EOR) in alkaline solution using cyclic voltammetry (CV) and chronoamperometric (CA) measurements. Among the CVs for the MOR, all alloy samples showed higher current densities than pure Pd. Also the peak current densities for MOR of PdNi coatings are 5 to 8 times higher than that obtained on Pd coating depending on composition. Based on the ratio of the forward peak current to the backward peak current the tolerance of the catalysts to accumulation of carbonaceous species is determined. Besides this ratio increased with extending the anodic potential limit. The most tolerant catalyst is found to be Pd_0.74Ni_0.28 in methanol oxidation. Comparative study of methanol and ethanol electrooxidation in the alkaline media reveals that Pd_0.74Ni_0.26 alloy has a higher catalytic activity, as well as a better tolerance to accumulation of carbonaceous species.

Al-MCM-41 materials were prepared with different Al contents and used as supports for NiW catalysts. The supports and catalysts were characterized by XRD, N₂ adsorption-desorption, XPS, Raman, H₂-TPR techniques. The XPS result showed that the Al added to MCM-41 promoted the dispersion of W and Ni species. The Raman result showed that the Al added to MCM-41 favored the formation of the suitable W species. The H₂-TPR result showed that the Al added to MCM-41 can reduce the reduction temperature of W species on the catalysts. The hydrodenitrogenation (HDN) results showed that the HDN activity followed the order of NiW/Al-2 > NiW/Al-1 > NiW/Al-4 > NiW. Moreover, this tendency was also valid for the ratio of propylcyclohexane/propylbenzene (PCH/PB). The high HDN activity and PCH/PB ratio of NiW/Al-2 are due to the well dispersion of the W and Ni species, the suitable W species and the low reduction temperature of W species.