CATALYSIS IN CHEMICAL AND PETROCHEMICAL INDUSTRY
The research proved that N-hydroxyphthalimid and its structural analogues are the catalysts for liquid phase oxidation of alkylaromatic hydrocarbons, use them without change of oxidation technology to isopropylbenzene hydroperoxide, will increase the productivity of the process of obtaining phenol and acetone. The quantum chemical method PM3 proved their practicability. The mechanism of oxidation reaction of isopropylbenzene, ethylbenzene and cyclohexylbenzene to relevant hydroperoxides in the presence of N-hydroxyphthalimid was justified. The correlation of the constants of speed of hydrogen atom abstraction from N-hydroxyphthalimid molecule and hydrogen molecule was determined.
Interlamellar space of the smectite clay minerals have been found as an excellent nano phase reactor due to their easy swelling property and the adsorption capacity. In this work size quantized nano particles of catalytically active noble metals have been generated within the interlamellar space of the smectite type clay minerals. Platinum and ruthenium intercalated/impregnated montmorillonite and hectorite catalysts were synthesised and characterized by various instrumental techniques. Catalytic activity of the synthesised catalysts was evaluated towards hydrogenation of cinnamaldehyde in liquid phase. The effect of various reaction parameters such as temperature, hydrogen pressure, solvents, and amount of catalyst and time on stream on conversion and selectivity were studied and the results are discussed. The studies revealed that noble metal intercalated/impregnated clay catalysts were very effective in hydrogenation reactions as they showed significant conversion and selectivity. Comparison of catalytic activity made with the impregnated catalysts showed that the intercalated catalysts were better than impregnated catalysts in terms of conversion and selectivity.
СATALYSIS IN PETROLEUM REFINING INDUSTRY
In order to increase the yield of C2–C4 light olefins compared to conventional catalytic cracking we studied experimentally the effect of temperature and catalyst/feed ratio on the main products distribution of crude oil catalytic cracking on bizeolite catalyst and industrial catalyst LUX. Bizeolite catalyst contains ultrastable zeolite Y and ZSM-5 in equal amounts, the catalyst LUX – 18 % mass fraction of Y zeolite in HREE form. Test results showed that in the range of ratios catalyst/feed 5-7 and temperatures 540-560 °C with a deep catalytic cracking of the hydrotreated vacuum gasoil on bizeolite catalyst C2–C4 olefin yield reaches 32–36 wt.%. The yield of gasoline is about 30 wt.%. Under similar conditions, the cracking catalyst in a series of suites overlook light olefins and gasoline are 12–16 and 37–45 wt.%, respectively. The distribution of final products in deep catalytic cracking of various hydrocarbon fractions (vacuum gasoil, gas condensate and its fractions after distillation of boiling up to 216 °С, as well as the heavy residue hydrocracking) to bizeolite catalyst. It is shown that the fraction of gas condensate and residue hydrocracking may be an additional source of hydrocarbons in the olefin production.
In order to develop an effective catalyst for the low-temperature
hydrogenation of aromatic hydrocarbons the authors prepared and
studied a series of catalysts containing precious metals on the support – hyper-cross-linked polystyrene, which has developed specific surface area (> 1000 m2/g) and high thermal stability. There are tests of Pt-and Pd-containing catalysts based on hyper-cross-linked polystyrene, carbon and alumina supports in hydrogenation reactions of simple (benzene, toluene), branched (n-butylbenzene) and polycyclic (terphenyl) aromatic compounds. Found that in reactions of hydrogenation of aromatic hydrocarbons on the activity of hypercross-linked polystyrene catalysts are comparable or higher than the activity of catalysts with noble metal catalysts based on Al2O3 and sibunit; the hyper-cross-linked polystyrene catalysts have higher selectivity for the hydrogenation of benzene in a mixture of benzene and toluene. By IR spectroscopy of adsorbed CO the electronic state of metals was studied in the Pt (Pd)/hyper-cross-linked polystyrene catalysts. When the catalysts testing in hydrogenation of terphenyl it was found that the Pt-containing catalyst at hyper-crosslinked polystyrene can reversibly work in cycles of hydrogenationdehydrogenation (terphenyl – tercyclohexane), what is promising for the use such catalytic systems for the creation of composite materials for hydrogen storage.
СATALYSIS AND ENVIRONMENT PROTECTION
Modified LaCoO3 and LaMnO3 were investigated as catalysts for low
temperature flameless combustion of methane. Modifications were
carried out by the substitution part of La for Sr+2 and Ce+4, by the addition of 0,5 % of Pt or Pd and by the substitution with Ag, which have limited solubility in the perovskite structure and may exist as intraframework Ag+ and extraframework metallic silver. Catalysts were synthesized by flame pyrolysis, which lead to a significant increase of both surface area and thermal resistance in comparison with the catalysts prepared by traditional sol-gel method. Samples were mainly characterized by XRD, BET and TPR techniques. Catalytic activity for the flameless combustion of methane was investigated by means of bench scale continuous apparatus, equipped with a quadrupolar mass spectrometer. In addition the resistance of every catalysts against sulphur poisoning was tested by using tetrahydrothiophene (THT) as poisoning agent. In most cases modification of perovskites led to an activity improvement, which was much more evident in the case of silver substitution. All the FP-prepared catalysts showed full methane conversion below 600 °C, with CO2 and H2O as the sole detected products. Sr-substitution and addition of noble metals increased resistance to sulphur poisoning, while silver was not effective from this point of view, its main advantage being a substantial increase of the initial activity, which lead to satisfactory performance even after poisoning.
INDUSTRY ENGINEERING PROBLEMS. OPERATION AND PRODUCTION
Extending the life of the industrial catalyst is possible by improving
the technological conditions of its operation. This will help eliminate
possible factors deactivation of the catalyst. Feature of the process
of catalytic dehydrogenation of hydrocarbons is unsteady due to the
deactivation of the catalysts.The article presents the results of the
simulation of industrial process catalytic dehydrogenation of higher
alkanes C9–C14 – a key stage in the production of linear alkyl benzene. Described in stages: 1) thermodynamic analysis of the reactions by quantum chemistry methods, 2) estimation of parameters of the kinetic model solution of the inverse kinetic problem, 3) the choice of catalyst deactivation by coke of the equation, 4) development of methods to increase the resources of the dehydrogenation catalyst with time-dependent model based on quantitative records added to the water reactor in the range 470–490 °C. Proposed on the basis of these models, technological system of higher alkanes dehydrogenation allows calculation of the forecast of the reactor under different conditions of water supply. It is shown that when water resource is increasing portions of the catalyst is increased by an average of 20–30 %.
DOMESTIC CATALYST
The article shows the possibility of improving the porous structure and adsorption properties of commercial activated carbons by ε-caprolactam modifying. The use of ε-caprolactam (the product of large-tonnage organic synthesis) as modifying agents can regulate directionally specific surface area and mesopore volume of activated carbons, and the conditions of modification change the chemical composition of the surface of carbon adsorbents and, consequently, their adsorption properties. The process of modifying was conducted in three phases. First: the adsorption of ε-caprolactam from an aqueous solution and heating at 300 °С in the presence of atmospheric oxygen. Second, the carbonization in argon at 900 °С, and three: gas-vapor activation of adsorbents obtained at 900 °С. After each stage, the parameters of porous structure on the adsorption of N2 and adsorption characteristics in relation to benzene, iodine, aqueous solutions of ε-caprolactam and copper sulfate (CuSO4).During the modification of carbonized samples with an initial ε-caprolactam content of 2 %, there is increase in mesopore volume up to 100 % compared to the original industrial activated carbon AG-OV-1. Depending on the stage of modification increases the adsorption: benzene at 50 %, the adsorption of iodine from aqueous solution at 20 %, ε-caprolactam adsorption from aqueous solutions by more than 30 % of the copper ions (II) more than 70 %, compared with the adsorption these substances in the original coal AG-OV-1. A method of producing these modified adsorbents has no analogues abroad, is patented and can be used in the industry. The initial is possible to use a budget industrial activated carbons. Can be obtained carbon adsorbents with given structural and adsorption properties.
Identifying the role of microwave radiation in the synthesis of porous Al/γ-Al2О3 support used in catalysts, is a fundamentally new direction of research processes, stimulated by a microwave field. This paper presents the results of the synthesis of porous Al/γ-Al2О3 support actively absorbing electromagnetic radiation of the microwave range. Expected to further its use of catalysts for heterogeneous catalytic reactions, stimulated by the energy of the microwave field. The possibility of strong absorption of microwave radiation with a frequency of 2450 MHz samples obtained by hydrothermal treatment of industrial aluminum powders in the presence of the hydrogel of aluminum hydroxide, followed by sintering in the microwave. The average temperature of the sample mass Al/γ-Al2О3 support, achieved under the influence of microwave radiation of varying intensity, comparable to the
temperature required for the occurrence of heterogeneous catalytic
reactions in the gas phase, in traditional heating the catalyst mixture. It is established that the hydrothermal treatment of aluminum powders in the presence of pre-cooked the hydroxide is only needed for the chemical bonding of aluminum crystallites with the surrounding oxide shell. The properties of the carrier to absorb microwave energy determined by a combination of metal and oxide phases.
INFORMATION
ISSN 2413-6476 (Online)