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Kataliz v promyshlennosti

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No 5 (2011)
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2011 - INTERNATIONAL YEAR OF CHEMISTRY

5-19 102
Abstract

In the early 1990’s, the progress in modern microelectronic technologies gave an impetus to studies of specific behavior of microchannel systems in various physicochemical processes. The microchannel systems were shown, with heat exchangers, mixers and microchannel reactors (microreactors) as examples, to intensify all the processes in the microchannels. In the present review paper, principal criteria, that make possible to classify a flow system as the microchannel one, are discussed. Three main catalytic processes – steam conversion, partial oxidation and autothermal conversion of light hydrocarbons and alcohols into hydrogen-containing gas – are considered and analyzed. It is shown with methane and methanol as examples that the process of hydrogen generation is enhanced indeed in the microreactor. In steam conversion of methanol catalyzed by Zn/TiO2 at 450 °C, the specific hydrogen productivity per catalyst weight was as high as 78,6 L/(h·gcat), the outlet quantity of carbon monoxide being no more than 1 mol.%. In partial oxidation of methane over catalyst La0,2Zr0,4Ce0,4/LaNiPt (0,48 g) in a microreactor at 700 °C, the specific hydrogen productivity was 521 L/(h·gcat) per catalyst weight and 42 L/(h·cm3) per reaction zone volume. When so, the thermal capacity (heat generated at hydrogen combustion) is 117 kW for the microreactor with 1,0 dm3 reaction volume that is comparable to the power of the gasoline engine of a modern vehicle. Hydrogen production from bioethanol, gasoline and diesel fuel also seems promising. Inspection of relevant literature in the field demonstrated that these fuels can compete successfully with methanol and methane, even though the catalytic conversion proceeds at temperatures 650 °C or higher. Results obtained in developing fuel cell – catalytic generators of hydrogen-containing gas with a low content of carbon monoxide (less than 20 ppm) – are reported in the last Section. Integrated microchannel systems are shown to be the most promising fuel cells.

20-34 53
Abstract

Widely applicable of industrial bi-and polyfunctional catalysts necessitates a new approaches to the development of kinetic models that take into account the coexistence of different types of active sites on catalysts surface, with different activity and selectivity for the main and byreaction, adsorption properties, structure, including nanostructure, the coordination environment, resistance to deactivation, components of the reaction medium or extraneous chemical impurities. From the perspective of this approach, the authors suggest in their work kinetic data, taking into account the contribution of different types of active sites in the catalytic process. We consider the practical application of the proposed approach to develop models of the kinetics and mechanism of industrial specific processes followed with catalyst deactivation: catalytic combustion of xylene on Pd catalysts, with the participation of two types of active sites, and dehydrogenation of isobutane on Pt nonpromoted and promoted catalysts, suggesting the participation of three types of active sites.

34-44 98
Abstract

An electrical discharge in liquid is considered. The conditions of the discharge existence are analyzed. The conditions of nanoparticles producing by the electrical discharge in liquid are described. The description of reactor and the results of obtaining of copper sols are presented. The results of obtaining of nanometals by the electric discharge in liquid for the using in three-phase catalytic processes are considered. The using of fine-grained metals in the catalytic processes of epoxidation, liquid-phase oxidation, hydrogenation is resulted. The perspectives of the using metal sols for the obtaining of deposited metal catalysts are shown. The elements of a plasma multiphase mixing reactor design are described.

44-53 137
Abstract

The review presents data on the main areas of application of molybdenum and tungsten carbides as catalysts for several industrially important reactions and the basic solutions for the synthesis of catalysts. Some of these methods can be considered as the initial phase of technology development of industrial catalysts based on molybdenum and tungsten carbides. The greatest prospect as a catalyst in the CO conversion by water vapor have a composition based on Mo2C.

54-61 120
Abstract

A mathematical model for isoamylene to isoprene dehydrogenation on an industrial self-regeneration iron-potassium catalyst is proposed. The model takes into account the size distribution of catalyst particles, the effective diffusion coefficient, rate constants and activation energies of forward and reverse reactions. The mathematical model can adequately describe the process of dehydrogenation in industrial reactors by varying operational parameters (feed rate, the degree of dilution and temperature at the reactor inlet).

61-68 88
Abstract

Currently, more and more interest grow to use a renewable biomass for producing fermentable sugars, organic and amino acids, which can be transformed into various useful products: polymers, materials for the pharmaceutical industry, food and fodder products. The conversion of vegetable polysaccharides to fermentable sugars is one of the most important stages in the processing chain of the bioconversion of cellulose wastes, taking place on the hydrolytic enzyme biocatalysts. Creation of recombinant strains P.verruculosum, producing cellulase complex with an additional increase in the activity of β-glucosidase, and xylanase is an urgent task in obtaining industrial strains of microorganisms that produce enzymes needed for high conversion of vegetable material. In this paper we obtain enzymes, biocatalysts for the conversion of biomass into simple sugars, with the increased activity of the heterologous exo- 1,4-β-glucosidase A.niger and endo-1,4-β-xylanase P.canescens using histone expression system in recombinant strains of P. Verruculosum; there is analysis of properties of new enzymes, studied fermentable ability of these drugs in the hydrolysis of shredded aspen and pine wood, which is waste of wood-processing, also a agricultural waste – bagasse. The utilization of these enzymes has the advantage compared to known analogs, because the compositions of new biocatalysts are more balanced, that offers you the highest yield of sugars without the cost of preparing the mixed individual drugs. It is shown that increased levels of xylanase and β-glucosidase (cellobiase) activities in the new biocatalyst resulting in 20–30 % increase yield of sugars and glucose reducing in the hydrolysis of powdered plant material – pine and aspen wood, also bagasse. The resulting enzyme preparations have potential applications in the woodworking industry and agriculture at the stage of polysaccharides cell wall making in fermentable sugars, such as the production of biobutanol. Appropriateness of using of new biocatalysts is a fermentable high performance of natural substrates, resulting from the balanced component of the enzyme preparations. Multienzyme complex of new biocatalysts can reduce the dosage of enzyme preparations in the hydrolysis process of vegetable waste.

69-75 72
Abstract

It’s established experimentally that the precious metals: gold, silver, platinum, rhodium, palladium, iridium and ruthenium are contained in the gas and liquids moving in nonconcentrated nitric acid plants, working by W. Ostwald (1902) technology on platinum, rhodium-palladium catalyst with the formation of nitrous gases. It is established that noble metals are allocated to nitrous gases, condensation of nitric acid and nitric acid due to loss of catalyst and ammonia-air mixture and the water feed to the stage of absorption of nitrogen oxides, as well as from the materials of units devices. The precious metals are nanoparticles in feed and unit materials, thay pass into the nitrous gas, condensate and nitric acid. It is noted that the total mass of noble metals in the condensate of nitric acid and nitric acid, much higher than the total mass of platinum, rhodium and palladium, the catalyst lost to the condensate, for example, in approximately three times. At pilot plant the experiments to allocate the concentrate containing 92–95 % precious metals, from the condensation of nitric acid and nitric acid were carried out. There are technology and key equipment for the unit to select a precious metals from nitric acid by the domestic non-concentrated nitric acid unit type UKL-7 capacity of 120000 tonnes per year, based on 100 % HNO3. There are approximate technical and economic indices of the node in the unit UKL-7 JSC «Dorogobuzh». It’s shown that the timing of cost recovery unit will not exceed 7 and 10 months at 100 % and 70 % feed loading of the unit.

75-80 225
Abstract

The paper is devoted to the thirtieth anniversary of polypropylene production, contained information about technical activities implemented in «Tomskneftekhim» company to improve the process. The article presents the results of the polypropylene production company «Tomskneftekhim» using propylene polymerization catalytic systems based on δ-TiCl3 type «Stauffer», which made at «Tomskneftekhim»; micro-spherical TiCl3, produced from 1986 to 2009 at the unit designed by oun domestic technology; pilot batch of titanium-magnesium catalyst IK-8-21, produced in 2008 at a pilot plant by Boreskov Institute of Catalysis technology; and commercial titanium-magnesium catalyst series Lynx manufactured by BASF (I, II and IV generations on standard classification). The package of scientific and technical measures were implemented to modernize the production of polypropylene, to organize the production of more efficient catalysts, to improve the polymerization process, to develop and implement the technology of production of new types of polymers, to increase competitiveness of the products in the market and profit. The results of the production transfer to use the advanced titanium-magnesium Lynx series catalysts are presented. Similar experience of such independent modernization of large polymer production without using engineering companies and licensors services in our country is not available. The complexof designed and implemented technical improvements for the process are currently patenting.



ISSN 1816-0387 (Print)
ISSN 2413-6476 (Online)