Catalysts prepared by the modification of FIBAN K-4 and FIBAN X-1 fibrous ion exchangers with the hydroxides of iron and manganese were developed and tested in a water deoxygenation process. It was established that the samples obtained by the supporting of Fe(III) hydroxide onto the FIBAN X-1 ampholyte were most effective. The conclusion that the high activity of the catalytic system is caused by the formation of a mixed phase of Fe(II) and Fe(III) hydroxides of the spinel type containing mobile (weakly bound) lattice oxygen was made. A reaction scheme was proposed to explain the reaction mechanism.

The thermal transformations of anionites synthesized on the basis of a polyacrylonitrile fiber are studied. During the heat treatment of the weakly basic anionite FIBAN A-5, the cleavage of amino groups occurs via two routes. In the case of the strongly basic anionite FIBAN A-6, dealkylation and deamination occur during heating and the dealkylation of quaternary amino groups accompanied by formation of tertiary amino groups predominates. The thermal degradation of anionites proceeds much more intensely in an aqueous medium than in an atmosphere of inert gas owing to participation of water hydroxyl in the mentioned reactions.

A procedure for the preparation of a fibrous palladium-containing catalyst for the removal of dissolved oxygen from water was developed. This procedure includes the preliminary modification of an anionexchanger fiber with carboxylate ions, which makes it possible to localize metal clusters in a thin subsurface layer of a fiber at the subsequent stages of the ion-exchange introduction of palladium into the carrier and the reduction of palladium. It was found that the higher activity of fibrous palladium-containing catalysts based on the citrate forms of anion exchangers, as compared with that of samples based on the chloride forms, was due to the predominant arrangement of reduced metal clusters on the external surface and an adjacent thin layer of the fiber.

A number of platinum-based catalysts bonded on carbon fiber karbopon were prepared using alcohol solutions of H 2 PtCl 6 . The catalytic activity of the samples was determined in the low-temperature oxidation of carbon monoxide by oxygen. The effect of the solvent nature of the precursor on the activity of the catalysts was determined. The best results were obtained in the presence of 1.5% Pt/karbopon catalyst prepared using isobutyl alcohol; 100% CO conversion was achieved in respiratory treatment (12000 h −1 , room temperature).

A number of supported-metal (Pt, Pd) catalysts based on Karbopon nonwoven carbon fibers were prepared by deposition from hydrosols and by ion exchange. The catalytic activity of the catalysts in low-temperature oxidation of carbon monoxide by atmospheric oxygen was determined. Catalyst samples were studied by transmission electron microscopy.

Changes in the nature and concentration of functional groups in the anion exchanger at oxidation of hydrogen sulfide in Fe(II)-ethylenediaminetetraacetate/anion exchanger catalytic system were studied.

Adsorption-catalytic process for carbon disulfide removal by means of the use of adsorbent and catalysts on the basis of carbon materials is developed. The process consists of adsorption of carbon disulfide from purified air, its steady desorption in inert gas flow, hydrolysis of carbon disulfide with hydrogen sulfide yielding, and oxidation of generated hydrogen sulfide to elemental sulfur. Efficient catalysts for carbon disulfide hydrolysis (5% TiO2, 1% CaO/KAU) and hydrogen sulfide oxidation (Fe-EDTA/carbopon) are developed. The most favorable parameters, which provide a complete carbon disulfide removal from air, are determined for all steps of the purification process. (c) 2005 Elsevier B.V. All rights reserved.

The distribution of acid centers with respect to their strength in sulfocationite granules and fibers with different cationic compositions was studied using a new variant of the thermal desorption method. The in fraction of strong acid centers was found to increase as the exchange capacity of the H-form of dehydrated (120 degrees C, 2 h) sulfocationite grew. The acid properties of sulfocationites with exchange cations of various natures correlated with their catalytic activity.

The effect of the complexonate solution pH on the nature and amount of ethylenediamine tetraacetate complexes of iron, immobilized on a FIBAN A-5 fibrous anionite, and their catalytic activity in H2S oxidation by molecular oxygen was studied.

The activity of fibrous ion exchangers based on polyacrylonitrile containing immobilized iron ethylenediaminetetraacetate complexes in oxidation of hydrogen sulfide to elemental sulfur with molecular oxygen was studied. The effect of various factors on the activity of the prepared catalytic systems was analyzed.

The catalytic activity of M.EDTA complexes (M = Fe, Mn, V) fixed on a fibrous ion exchanger in the oxidation of H2S to elementary sulfur was studied. IR spectra for the complexonate solutions were obtained. The physicochemical properties of the M.EDTA complexes were considered. It was concluded that the high activity of the Fe.EDTA complex is due to optimal thermodynamic properties of the Fe3+.L/Fe2+.L pair and the formation of the active intermediate complex HS-...Fe.EDTA...O-2, which provides a high rate of electron transfer.

The conversion of a mixture of NO and CO on an industrial aluminopalladium catalyst APK-2 was studied. The kinetic constants of the occurring reactions are determined, and their possible mechanism is discussed.

Oxidation of hydrogen sulfide by oxygen at 16-30 degrees C in presence of fibrous strong-base FIBAN A-1 anionite with fixed Fe-EDTA complexes has been studied. It was found that H2S conversion rises with decrease of temperature, increase in anionite humidity and complex content. A catalyst samle prepared on the basis of Cl-form of anionite displays higher activity. Elevated oxygen content ill the initial gas mixture results in considerable increase of catalyst efficiency.

The rate constants for ethane and methane conversion during the pyrolysis of methane-ethane mixtures under conditions approaching a regime of complete mixing are determined. It is shown that the ethane decomposition rate decreases in the presence of methane, and the inhibiting effect is enhanced with increasing the methane concentration. In turn, the methane conversion rate grows when the ethane concentration is increased in a mixture. The regularities obtained are explained by the participation of atomic hydrogen in competitive reactions occurring in the system. During the catalytic conversion of methane-ethane mixtures, the concentration of atomic hydrogen in the reaction zone is 3 - 8 times higher than during the thermal process. This results in the considerable increase of the methane conversion rate in the presence of a catalyst and in the reduction of methane's inhibiting effect upon ethane decomposition.

One promising trend in improvement of pyrolysis of hydrocarbon feedstocks is the use of heterogeneous catalysts in the process. The industrial use of highly effective catalysts would result in substantially increased product yields and in decrease of energy consumption in comparison with the requirements of drastic thermal processes. The aims of the present work were to obtain a mechanically strong coarse-pored ceramic support for pyrolysis catalysts and to study the influence of various factors on formation of its structure. The support material was made from an industrial ceramic mass of the following composition (%): koalin 30, plastic refractory clay 21, quartz 32, pegmatite 17. Various additives were used for formation of a porous structure: noncombustible highly porous (pumice, claydite), partially combustible (shungite), and completely combustible (SKT) activated carbon). The authors results show that 15 mass % of SKT carbon (particle size 0.1-0.2 mm) and 1-2 mass % of sodium trimetaphosphate should be added to the ceramic mass. The crushing strength of the resultant support samples reaches 550-630 kg/cm/sup 2/, with 34-35% porosity. Under the optimal conditions of pyrolysis of a straight-run gasoline fraction the catalyst obtained by deposition of 12 mass % of In/sub 2/O/sub 3/ and 4% K/sub 2/Omore » on the synthesized support gives a yield of 39-41 mass % of ethylene and 61-62 mass % of unsaturated C/sub 2/-C/sub 4/ hydrocarbons, with 88-90 mass % gasification.« less