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The effect of the dilution of a synthesis gas with nitrogen on the activity, selectivity and productivity of a Fischer–Tropsch reactor with a fixed bed of granular catalyst during synthesis on a pilot plant of a full cycle for the conversion of natural gas into synthetic oil is studied experimentally. Experimental data are presented that were obtained at different contents of nitrogen in the synthesis gas: up to 2, 50, and 70%. Analysis of the experimental data shows that diluting the synthesis gas contributes to an increase in the selectivity to C5+, and a decrease in the selectivity to methane. A drop in the reactor’s productivity observed upon the dilution of synthesis gas can be compensated for by increasing the consumption of synthesis gas. The negative effect of decrease in the pressure of FT synthesis from 2 to 1.5 and 1.0 MPa on the catalytic FT synthesis performed on a twice-diluted synthesis gas at a synthesis gas space velocity of 4000 h–1 is demonstrated.

The effect of syngas dilution with nitrogen on the activity, selectivity and capacity of the Fischer–Tropsch reactor with a fixed granulated catalyst bed was studied during the synthesis at the integrated pilot plant for conversion of natural gas to syncrude. Experimental data were obtained at different nitrogen content in syngas: up to 2, 50 and 70 %. The analysis of experimental data shows that the dilution of syngas increases the selectivity to C5+ and decreases the selectivity to methane. The decrease in the reactor capacity observed upon dilution of syngas can be compensated by increasing the syngas flow rate. A decrease in the pressure of the Fischer–Tropsch synthesis from 2 to 1.5 and 1.0 MPa was shown to exert a detrimental effect on the catalytic performance of the process carried out with a twofold dilution of syngas at its hourly space velocity of 4000 h–1.

A cobalt Fischer–Tropsch synthesis catalyst supported on titania-doped silicon carbide is synthesized and comprehensively studied by a number of physicochemical means. The dynamics of the behavior and deactivation of the catalyst was studied after its stable operation for 1500 h during continuous experimental resource testing with a periodic change in the syngas flow rate and pressure and the process temperature. This catalyst has two types of active sites, on which products with different Schulz–Flory distribution parameters form. Depending on the process regime, the effective formation of soft waxes or more high-molecular-weight products is possible.

A cobalt catalyst supported on titania-doped silicon carbide for the Fischer – Tropsch synthesis was synthesized and comprehensively studied using various physicochemical methods. The dynamics of behavior and deactivation of the catalyst, which showed a stable operation for 1500 hours, was studied in a continuous pilot-plant lifecycle test with periodic variation of flow rate, syngas pressure and process temperature. This catalyst has two types of active sites on which products with different parameters of the Schulz – Flory distribution are formed. Depending on the process mode, the efficient formation of «soft waxes» or products with a higher molecular weight can occur.

On the basis of analysis of experimental data on the temperature in a reactor for Fischer–Tropsch synthesis, a method for prediction of loss in thermal stability of such a reactor by extrapolating the reactor temperature in time with the use of the first-order and second-order time derivatives of experimental data on this temperature has been developed. Since, in this case, the calculation of derivatives is an incorrect procedure because of the rapid changes in the reactor temperature and the accidental errors in its measurement, this problem was solved using the Tikhonov stabilizing-functional method. An integro-differential equation of calculating the first-order and second-order time derivatives of experimental temperatures of the reactor, providing a minimum of the stabilizing functional, has been derived. The possibility of predicting the behavior of the temperature in a reactor under the conditions of loss in its thermal stability was demonstrated through the comparison of calculation and experimental data on the reactor temperature. The method proposed can be used for development of an automated system for control over the working conditions of a reactor for Fischer–Tropsch synthesis for prevention of its thermal explosion.

The productivity of Fischer-Tropsch reactors is determined by the efficiency of heat and mass transfer processes inside the catalyst granules. To reduce the diffusion resistance the granules base is made from ceramic highly porous material. The porous structure of the granules causes a discrete arrangement of cobalt metallic microparticles whose size can reach tens of microns. Cobalt particles are the active centres on which the synthesis reactions are realized. The distance between these active centres significantly exceeds their characteristic size and the homogeneous model for heat and mass transfer is incorrect. In our paper a mathematical model of heat and mass transfer processes in a porous spherical granule with localised active centres is proposed. The heat of the exothermic synthesis reaction is removed from the surface of the granule by heat transfer into the synthesis gas stream washing the granule. The components of the synthesis gas enter to the granule surface as a result of mass transfer. On the basis of the mean-field approach the values of the temperature and concentration of the synthesis gas components at the active centres inside the granule were determined. In the reactor tube, where the catalyst granules are placed, there is a critical temperature. The excess of the critical temperature leads to a thermal explosion, i.e. a substantial overheating of the active centres. In this case, the surface of the catalyst granule is superheated slightly. The principal difference between the homogeneous and heterogeneous models in catalytic reactions is discussed. We analysed influence of the temperature inside the reactor tube, size of the granule, and coefficient of thermal conductivity on the thermal stability of the granule.

Composite pelletized catalysts for higher one-pass conversion and productivity in the Fischer–Tropsch process are reported. The introduction of aluminum metal powder as a thermal conductor leads to the formation of a new family of composite pelletized catalysts, very different from reference systems. In particular, these catalysts retain high activity and C5+ selectivity at increasing gas-hour space velocities of up to 5,000 h−1. The productivity of these composite catalysts increases almost fourfold for fivefold GHSV increase. Composite catalysts with different types of active cobalt (conventional, introduced by impregnation, or skeletal) show similar values of one-pass conversion and productivity but give different fractional and group composition of liquid hydrocarbon products. Testing of these highly productive catalysts in reactors with different aspect ratios showed that high productivity and one-pass conversion can be achieved in industrial-size units, where feasible liquid yield of up to 140 barrels per million standard cubic feet (MMSCF) of natural gas can be reached.

The formation of surface cobalt structures was investigated for a number of β-SiC-supported Fischer–Tropsch catalysts. Several different supports were used, both pristine and alumina-modified β-SiC. The techniques of temperature-programmed reduction, nitrogen physisorption, thermal gravimetric analysis, heat conductivity and catalytic testing in Fischer–Tropsch synthesis were employed. It was determined that despite highly similar manufacturer specifications, differences in support genesis may lead to different porosities, surface cobalt phase compositions and catalytic activity, even with the use of identical catalyst preparation procedures. The control of the formation of the surface cobalt structure can also be realized by parameters of the catalyst preparation, such as one- or multi-step impregnation from aqueous or ethanol solution and annealing in air or helium flow or without gas flow. These findings open avenues of research for the optimization of the whole catalyst formation route on the basis of identification of the most efficient surface cobalt phase composition and realization of higher thermal conductivity.

A mathematical model of heat and mass transfer processes in the grain of the Fischer-Tropsch synthesis catalyst is presented that takes into account the effect of the capillary condensation of the products of the synthesis in the pores of the catalyst. The influence of capillary condensation on the processes of the diffusion transfer of heat and mass in the catalyst grain is analyzed using the proposed model. Dependences of the efficiency factor of the grain on the pressure and temperature of the process and the partial pressure of various components of a mixture are presented. The possibility of determining the optimum pressure and temperature of carrying out the process for the catalyst of a certain structure is shown.

The possibility of synthesizing a new material—completely deuterated hydrocarbons—by the Fischer-Tropsch process has been demonstrated. This is the first step toward the formation of a research-and-production basis for the creation of a pilot plant. There was no isotope effect; consequently, the key characteristics of the synthesis and products were determined by the properties of the catalyst and reaction conditions, irrespective of whether hydrogen or deuterium was used in the starting mixture. Waxes were removed from the catalyst surface under mild conditions; this did not require any special equipment or the transfer of catalyst to another reactor. The chosen catalyst was highly stable and can be used in a pilot plant for the production of completely deuterated waxes. The first evaluation of the properties of the new materials showed that they were promising as solvents for NMR, radioactive labels, targets, neutron flux moderators, etc.

The decomposition of methane on catalysts prepared by metal deposition on carbon fiber was investigated. It was found that new carbon deposits having a threadlike form and a nanotube structure are formed on nickel-containing samples.

The formation of heterogeneous mercury-, zinc-, and copper-containing catalytic systems obtained by supporting salt components (SCs) without a solvent is studied. It is shown that due to strong interaction between SC and support, the size of salt clusters on the surface and their relative contribution decrease. That is, the concentration of excess salt phases decreases. The dispersity increases up to molecular distribution. When surface-linked two-dimensional disordered structures are formed, the state of salt phases in the compositions of catalytic systems changes. The surface mobility of salt clusters during the contact with the reaction medium is found. Compared to the systems obtained by impregnation with aqueous solutions, the proposed systems are 2-3 times more thermally stable, their surface is enriched in defect structures that are active in catalysis, and the processes of organochlorine synthesis become more efficient.

One of the most important problems in the synthesis of carbon nanotubes is the problem of controlling their morphology, namely: length, aspect ratio, alignment, etc. Catalytic synthesis of carbon nanotubes in a suspended bed reactor allowed to study the possibilities of controlling the growth of nanotubes by introducing a certain amount of water vapor and carbon-containing materials in the reaction zone. The synthesized long carbon nanotubes were studied by Raman spectroscopy, transmission and scanning electron microscopy. We found that water concentration influences both yield and the structure of nanotubes. It is shown that the yield of centimeter-long nanotubes can be maximized at an optimum H2O/C ratio, while deviations dramatically change morphology and thickness of the nanotubes.

1. It has been shown by means of x-ray phase analysis that in supported copper chloride catalysts for the oxidative chlorination of hydrocarbons, the salt component interacts with the support (metastable aluminum oxides or an amorphous aluminosilicate), this interaction leading to the formation of a complex multiphase system. 2. The structure of the support influences the crystallization of the excess salt component, resulting in oriented growth of the crystals. 3. On an aluminosilicate support, copper hydroxochlorides are formed selectively, so that they constitute a large part of the supported salt component.

1. In copper-containing salt catalysts for oxidative chlorination on various carriers, catalysts with the same amount of applied salt component have a different surface composition as a result of the reaction with the carrier. The formation of surface melts is a function of the nature of the carrier and the concentration of the salt component. 2. “Separation” of the KCl·CuCl2 salt system with formation of surface states characteristic of KCl/carrier and CuCl2/carrier systems takes place on carriers with a developed surface. 3. Elimination of water molecules and hydroxyl groups from the surface of the carrier is significantly facilitated under the effect of the salt component. 4. Due to the reaction with the carrier, the salt component in the catalyst decomposes more easily than the individual salt system.

1. By means of electron microscopy and an investigation of adsorption, involving x-ray diffraction and DTA, the observed morphological structures have been characterized in the catalytic systems copper(II) chloride-α-aluminum oxide and copper (II) chloride-potassium chloride-α-aluminum oxide, 2. When the catalytic, systems are heat-treated, the salt clusters acquire mobility as a consequence of the formation of fusible compositions or surface migration of salt phases in a premelting state. When this occurs, changes are observed in the structure and surface area of the salt clusters.

1. Copper chloride catalysts for oxidative chlorination of hydrocarbons are multicomponent heterogeneous systems which consist of both melts of varying composition and of coexisting solid phases formed during thermolysis of the salt component. 2. In copper-containing salt catalytic systems, the active component reacts with the carrier with the formation of new phases. 3. In thermolysis of these systems, the Headwall effect is observed, which permits identifying the phase transitions and transitions of the “order-disorder” type in the crystal lattices when the system is heated by the method of differential thermogravimetric analysis.

1. In catalysts containing copper salts on aluminum oxide support, various structures containing copper have been found that form by the reaction of the salt with the support surface. 2. The kind of structure that forms depends on the phase composition and the acid-base properties of the support surface. 3. Surface structures can affect the coalescence of catalyst particles under reaction conditions, and thus change the hydrodynamics of a fluidized bed.