Z. R. Ismagilov

Direct conversion of methane on Mo/ZSM-5 catalysts to produce benzene and hydrogen: achievements and perspectives

Development of highly effective catalysts for one-stage conversion of light hydrocarbons with high selectivity to valuable products will solve such problems as efficient utilization of natural and oil-associated gases, and environmental protection. Methane dehydroaromatization (DHA) over Mo/ZSM-5 catalysts is a promising process for direct production of valuable aromatic compounds and hydrogen from methane. This review focuses on the range of issues dealing with the effect of catalyst composition, preparation, pretreatment and operation conditions on the physicochemical properties and activities of Mo/ZSM-5 catalysts in DHA reaction. The concepts of the reaction mechanism and the nature of the active molybdenum forms are reviewed. Various aspects of the Mo/ZSM-5 deactivation under reaction conditions and methods of their regeneration are discussed. Some approaches for improvement of the Mo/ZSM-5 performance in DHA reaction are addressed in the review in detail. The perspectives of the methane dehydroaromatization process are also presented.

New technology for production of spherical alumina supports for fluidized bed combustion

Abstract Fluidized bed catalytic combustion has proved to be very promising for industrial application. The milestone problem is the development of support and catalyst with a high mechanical and thermal stability. We have developed a new technology for production of alumina supports with desired spherical shape, texture and structure. In this paper several pathways to produce aluminum hydroxide of a pseudoboehmite structure including conventional and new technologies are discussed. Properties of spherical granules depend on the method of granulation and most attention has been paid to development and optimization of hydrocarbon–ammonia molding to produce uniform alumina spheres. Several methods to estimate mechanical strength of spherical aluminas are applied to evaluate mechanical durability of prepared catalysts in a fluidized bed. Optimization of high quality spheres production focused on study of the effect of initial hydroxide properties and molding conditions on properties of the final product. Modification of spherical alumina with oxides of Mg, Ce, La and Si proved to be effective to substantially improve the mechanical and thermal stability. This effect is most pronounced when pairs of these dopes are introduced simultaneously.

Selective catalytic oxidation of ammonia to nitrogen

The activity of catalysts of different nature in ammonia partial oxidation has been studied. Vanadium-titanium, copper-titanium catalysts and copper-substituted zeolites are the most active in the reaction. These catalysts are promising if used as honeycomb monoliths.

A catalytic heat-exchanging tubular reactor for combining of high temperature exothermic and endothermic reactions

A multifunctional catalytic heat-exchanging (HEX) tubular reactor for combining exothermic and endothermic reactions has been developed and tested for catalytic methane oxidation and methane steam reforming. The methane combustion and steam reforming catalysts were synthesized on the heat-conducting metal foam support materials by application of preliminary plasma spraying of alumina in order to increase adhesive properties of the active layer. The HEX rector with perovskite-supported catalyst on Ni-Cr foam material on the external surface of the HEX tube and with Ni containing reforming catalyst on the internal Ni foam was successfully tested in methane combustion reaction combined with methane steam reforming.

Metal foam supported perovskite catalysts

The impregnation technique and the polymer coating method were applied to synthesize a LaCoO3 perovskite catalyst on a metal foam support. The synthesized catalysts were examined by X-ray diffraction analysis, BET method, scanning electron microscopy. The perovskite phase was characterized by temperature-programmed reduction and diffused reflectance electron spectroscopy. The activity of the catalysts was tested in the methane oxidation reaction.

Detoxication of water containing 1,1-dimethylhydrazine by catalytic oxidation with dioxygen and hydrogen peroxide over Cu- and Fe-containing catalysts

Abstract A number of Cu- and Fe-hydroxide containing catalysts, supported on oxide carriers, were prepared to provide the removal of 1,1-dimethylhydrazine from aqueous solutions via its oxidation by hydrogen peroxide and air oxygen. The Cu-containing samples as well as Fe/ZSM-5 are the most active catalysts in this reaction. The reaction products were analyzed by gas chromatography and UV–Vis spectroscopy. The effect of nature of the oxidizer and catalyst, pH and temperature on both the reaction rate and product composition was studied.

Application of plasma spraying in the preparation of metal-supported catalysts

Abstract Catalysts supported on metals are widely used today, but room still remains for further improvement of catalyst characteristics. The subject of this paper is the application of a plasma spray for the deposition of alumina coatings on metal substrates of different geometry (plates, foams) for subsequent synthesis of catalysts. The alumina layer sprayed successfully solves two different problems: (i) it serves as a washcoat on which a catalyst is synthesized, and (ii) it protects the metal surface from oxidation at high temperatures.

POROUS ALUMINA AS A SUPPORT FOR CATALYSTS AND MEMBRANES. PREPARATION AND STUDY

Porous alumina as single tubes and as a multihole structure with controlled properties has been prepared. It is shown that the porous structure of these supports can be controlled without burning out additives but by a variation of the ratio between the main alumina component (α-Al2O3) and aluminium hydroxide (binder) in the extrusion masses and thermal treatment conditions. Gas permeability measurements have been used for the characterization of the supports. The properties of the ceramics are shown to satisfy the requirements of membrane supports.

Properties and deactivation of the active sites of an MoZSM-5 catalyst for methane dehydroaromatization : Electron microscopic and EPR studies

The MoZSM-5 (4.0 wt % Mo) catalyst has been characterized by high-resolution transmission electron microscopy, EDXA, and EPR. Two types of molybdenum-containing particles are stabilized in the catalyst in the course of nonoxidative methane conversion at 750°C. These are 2-to 10-nm molybdenum carbide particles on the zeolite surface and clusters smaller than 1 nm in zeolite channels. According to EPR data, these clusters contain the oxidized molybdenum form Mo5+. The surface Mo2C particles are deactivated at the early stages of the reaction because of graphite condensation on their surface. Methane is mainly activated on oxidized molybdenum clusters located in the open molecular pores of the zeolite. The catalyst is deactivated after the 420-min-long operation because of coke buildup on the zeolite surface and in the zeolite pores.

Supported honeycomb monolith catalysts for high-temperature ammonia decomposition and H2S removal

Abstract Catalysts that have potential in simultaneous removal of H 2 S and NH 3 decomposition were developed. The monolith supports of high surface area and acceptable mechanical strength based on titania and silica–alumina precursors were prepared and tested. Preparation routine and composition of Mn, Fe and Cu oxides supported honeycomb catalysts have been optimized. Impregnated and washcoated monolith catalysts were tested in ammonia high-temperature decomposition.