Two different series of bifunctional hydroisodeparaffinization catalysts with deposited palladium and based on SAPO-11 and SAPO-31 are fabricated and studied, with (1) varied activity of the acidic component at a constant activity of the hydro–dehydrogenating component and (2) varied activity of the hydro–dehydrogenating component at a constant activity of the acidic component. It is shown that the temperature of 90% n-decane conversion on the catalysts with the same hydro–dehydrogenating activity depends linearly on the overall activity of the acidic catalyst component. The character of this dependence is identical for both structural types of SAPO-11 and SAPO-31 silicoalumophosphates. The bifunctional catalysts based on SAPO-31 are much more active than those based on SAPO-11. At the same overall activity of the acidic component, the temperature of 90% n-decane conversion on the Pd/SAPO-31 catalysts is 50°C lower than on the Pd/SAPO-11 catalysts. Ways of controlling the overall activity and selectivity of a hydroisodeparaffinization catalyst by varying the activity of the acidic and/or hydro–dehydrogenating component of a bifunctional catalyst are shown. An increase in the hydro–dehydrogenating activity of the catalyst enhances the hydroisomerizing activity of a bifunctional catalyst with virtually no changes in selectivity toward isomers. An increase in the overall activity of the acidic component also enhances the hydroisomerizing activity of a bifunctional catalyst, but appreciably alters its selectivity toward isomers.

The formation of coke on active sites in the entire volume of zeolite Y crystals has been experimentally confirmed. However, complete deactivation in the case of decationated zeolites is due to the blocking of zeolite space by coke deposition on the outer surface of the crystals. In this case, blocking occurs long before complete poisoning of the active sites in the bulk and filling the large cavities of zeolite Y with the coke. The model of the “inner” deactivation of zeolites Y is applicable only to dealuminated zeolites with a silica ratio equal to or greater than 70–75 or in the case of selective dealumination of the outer surface of the zeolite crystals.

The resistance to sulfur compounds is considered for nickel, platinum, and palladium metals deposited onto acidic supports, depending on the nature of a support. Catalysts containing nickel, platinum, palladium, and their sulfides as hydro-dehydrogenating components are studied in the reaction of n-octane hydrocracking. The supports are HY, ZSM-5, ZSM-23, and ZSM-12 zeolites and SAPO-11 and SAPO-31 silicoalumophosphates. It is shown that the deposited metals in the hydrocracking catalysts have different resistances to sulfur compounds, regardless of the properties of the acidic support under the conditions of the reaction. The hydrocracking process follows two different pathways, depending on the nature of the hydro–dehydrogenating component (a metal or its sulfides), its activity, and the ratio between the activities of the acidic and hydrogenating components. The first of these determines the predominant cracking of the initial paraffin at the initial stage, while the initial paraffin is subjected to dehydrogenation on the second pathway.

Palladium-containing catalyst based on binder-free granular sulfated zirconium oxide for n-butane isomerization has been investigated. It has been found that Pd content of 0.2–1.0 wt % slightly influences textural characteristics and other physicochemical properties of bifunctional catalysts; however, it determines their activity and selectivity in the reaction studied, with the optimal palladium content being 0.5 wt %. Parameters of the isomerization process have been studied depending on the composition of industrial n-butane fractions. It has been shown that impurities of isobutane, propane, neopentane, isopentane and pentane in an amount of no more than 2% do not exert a effect on isobutane production; nonetheless, the conversion of n-butane and selectivity for isobutane both increase when more pure n-butane fractions are used. It has been found that the process for isobutane production by isomerization of the n-butane fraction under the optimal conditions at H2 /n-C4 = 0.1 and 140–150°C makes it possible to obtain a high isobutane yield (up to 52 wt %) and avoid the undue formation of С1–С3 alkanes.

Part III of this work continues the study of the catalytic properties of new molybdenum carbide based hydroisomerization catalysts, which are resistant to sulfur compounds and allow the synthesis of waxy diesel fuels with the same quality characteristics as those of platinum-containing catalysts. The catalytic properties of such bifunctional catalysts as 7%Mo 2 C/SAPO-31 (LCCH-2) and 7%Mo 2 C/SAPO-11 (LCCH-2-2) in diesel fraction hydroisomerization in the temperature range of 320–400°C are compared. It is shown that LCCH-2 ensures a higher yield of the hydroisomerized diesel fraction with a lower freezing point as compared to LCCH-2-2 at temperatures above 320°C. The ratio between mono- and di-isomers in reaction products is analyzed. It is concluded that SAPO-31 based catalyst is more selective to the formation of terminal monosubstituted alkanes than SAPO-11 based catalyst. The resistance of both catalysts to deactivation with coke deposits (tests over 100 h at 320 and 360°C in hydroisomerization) is studied. It is established that LCCH-2-2 is less resistant to deactivation than LCCH-2. These findings are due to differences in acidity, the degree of uniformity in the distribution of acidic hydrogenating/dehydrogenating sites in the catalysts, and the structural type of their acidic supports.

The aim of this work is to develop a new hydroisomerization catalyst based on molybdenum carbides that is resistant to the influence of sulfur compounds and applicable for the synthesis of low-pour-point diesel fuels that are similar in parameters to the fuel synthesized using platinum-containing catalysts. In the first part of the work, supports with different porous structures and acidities (Beta, ZSM-5, ZSM-12, and SAPO-31) are synthesized and studied. In the second part of the work, bifunctional catalysts prepared by modifying these supports with nanosized molybdenum carbides are studied. All samples contain the same amount of Mo 2 C (10% in terms of the equivalent amount of MoO 3 ). The catalysts are tested using a model isomerization reaction of n -decane. The catalyst based on silicoaluminophosphate ATO (SAPO-31) proves to be the most effective one. In order to optimize its composition, larger batches of samples with different Mo 2 C contents (5, 7 and 10% in terms of the equivalent amount of MoO 3 ) are prepared. The catalytic properties are studied using the hydroisomerization of actual diesel fractions. The optimum content of Mo 2 C (7 wt %) in the bifunctional catalyst is determined.

Hydroisomerization catalysts based on nanosized molybdenum carbides are developed. Such catalysts are resistant to sulfur compounds and can be used for the synthesis of waxy diesel fuels with the same characteristics as on platinum-containing catalysts. In the first part of this work, acidic supports with different types of porous structure and concentrations and strengths of Brønsted acidic sites (e.g., silicoaluminophosphate SAPO-31, zeolite ZSM-12, modified zeolite Beta, and desiliconized zeolite ZSM-5) are synthesized for a new type of catalysts. Their physicochemical properties are studied by means of adsorption, temperature- programmed desorption of ammonia (TPD-NH 3 ), nuclear magnetic resonance (NMR) spectroscopy, and scanning electron microscopy (SEM).

Part 3 of the studies dealt with catalytic properties of the new catalysts based on molylbdenum carbides, resistant to sulfur compounds and providing manufacturing of low pour point diesel fuel with the quality indices identical to those obtained with platinum-containing catalysts. Catalytic properties of bifunctional catalysts 7%Mo2C/SAPO-31 (LCCH-2) and 7%Mo2C/SAPO-11 (LCCH-2-2) for hydroisomerization of diesel fractions were compared at the temperature range between 320 and 400 °C. It was shown that at above 320 °C the catalyst LCCH-2, against LCCCH-2-2, provided the formation of the hydroisomerized diesel fraction at a higher yield and freezing at a lower temperature. Inspection of the data on the ratio of total quantities of monomers and diisomers in the reaction products led to conclude that the former catalyst is more selective than the latter to the formation of terminal monosubstituted alkanes. Studies of the stability of both catalysts to deactivation with coke deposits (100 hour testing at 320 and 360 °C during hydroisomerization) revealed that LCCH-2-2 is less stable to deactivation than LCCH-2. The observed regularities were accounted for by differences in the acidities, degree of homogeneity of distribution of acid and hydrating-dehydrating centers through the catalysts under study, and types of structures of the acid support.

Patent information on the production of catalytic systems containing molybdenum and tungsten carbides and their application in the hydroisomerization of paraffinic hydrocarbons is reviewed. Analysis shows that modifying acid supports with molybdenum and tungsten carbides solves the problem of creating a stable catalyst for the hydroisomerization of paraffinic fractions. The resulting catalyst is resistant to sulfur-containing impurities in hydroisomerization feedstock.

The increasing the stability of the MFI type zeolite catalysts is actual for creating of high active catalysts for methanol conversion to C2–C4 hydrocarbon gases or hydrocarbons to aromatics – an important industrial processes. Three new approach to improve the stability of zeolite catalysts are proposed in the work: the selective dealumination on the outer surface of the MFI zeolite crystals; the structure-selective ion exchange on the external surface of the crystals, the use of isothermal (tubular) reactor. The influence of conditions of selective dealumination and structurally selective ion exchange on the molar ratio SiO2/Al2O3 of the zeolite and time between regeneration running in the conversion of methanol into hydrocarbons is studied. It is found that the selective dealumination of external surface leads to an increase of between regeneration running up to 3–5 times. Structure-selective ion exchange on the outer surface of the zeolite crystals can increase the time of running in 2–4 times, reduce the temperature and duration of recovery due to changes in the properties of the deposited coke. Application of the tubular reactor allows to facilitate the regeneration process compared with an adiabatic reactor by the formation of less condensed coke.

It is shown that catalysts based on Pt/SAPO-31 can be used for the single-stage conversion (in contrast to the two-stage commercial process) of vegetable oil into waxy diesel fuel components. The effect of the content of metal (0.5–2 wt % Pt) in the catalyst on its physicochemical and catalytic properties is studied. It is found that regardless of the platinum content, the activity of the catalysts diminishes during the reaction, as is indicated by a drop in their isomerization ability and the presence of oxygen-containing compounds in the reaction products. The physicochemical properties of Pt/SAPO-31 catalysts are studied via the IR spectroscopy of adsorbed pyridine, hydrogen chemisorption, and transmission electron microscopy. It is shown that the catalytic degradation is caused by the poisoning of the acid sites and a reduction in the active surface area of the metallic component. Possible ways of improving the on-stream stability of Pt/SAPO-31 samples in the hydroconversion of vegetable oil are described.

Increasing the operational stability of MFI-type zeolite catalysts is topical for the creation of highly efficient catalysts for the conversion of methanol or C2-C4 hydrocarbon gases into aromatic hydrocarbons, i.e., important industrial processes. This study proposes three new approaches to increasing the stability of zeolite catalysts: selective dealumination on the outer surface of MFI zeolite crystals, structurally selective ion exchange on the outer surface of crystals, and the application of an isothermal (multitube) reactor. The effect of selective dealumination and structurally selective ion exchange conditions on the SiO2/Al2O3 molar ratio in the zeolite on the interregeneration period duration in the conversion of methanol into hydrocarbons has been studied. It has been established that the selective dealumination of the outer surface increased the interregeneration period duration by 3–5 times. Structurally selective ion exchange on the outer surface of zeolite crystals allows us to increase the interregeneration period duration by 2–4 times and to decrease the regeneration temperature and duration due to the change of the properties of deposited coke. The application of a multitube reactor facilitates the procedure of regeneration in comparison with an adiabatic reactor due to the formation of less condensed coke depositions.

Microporous aluminophosphates and silicoaluminophosphates were obtained by hydrothermal synthesis with a number of symmetrical di- n -alkylamines as templates. The influence of the reagents and chemical composition of the starting reaction gel on the phase composition of the products obtained was studied. Pure ATO-type crystals were formed when the organic component was abundant in the reaction mixture and aluminum isopropoxide served as an aluminum source. Various physicochemical investigations revealed that the properties of the products obtained depend on the amine nature.

ZSM-12 zeolites synthesized by using different templates were modified by desilication treatment in alkaline medium. The samples before and after alkaline treatment were characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), N 2 physical adsorption, solid state NMR ( 29 Si MAS NMR), ammonia temperature programmed desorption (NH 3 -TPD) and FT-IR spectroscopy of adsorbed pyridine (Py-IR). The effects of desilication on the structure, acidity and catalytic performance in the alkylation of naphthalene with methanol over ZSM-12 zeolites were investigated. The results showed that acidity of ZSM-12 zeolites could be adjusted and mesopores were generated after alkaline treatment, so catalytic performance was effectively improved, and increase of naphthalene conversion, selectivity to 2,6-DMN and 2,6-/2,7-DMN ratio were observed over the alkaline treated samples.

The nonoxidative conversion of methane into aromatic hydrocarbons on high-silica zeolites ZSM-5 containing nanosized powders of molybdenum (4.0 wt %) and nickel (0.1–2.0 wt %) was studied. Data on the acid characteristics of the catalysts and the nature and amount of coke deposits formed on the surface of the catalysts were obtained using the thermal desorption of ammonia and thermal analysis. The microstructure and composition of Ni-Mo/ZSM-5 catalysts were studied by high-resolution transmission electron microscopy and energy-dispersive X-ray analysis. The formation of various chemical species in the samples was detected: oxide-like clusters of Mo within zeolite channels (∼1 nm), molybdenum carbide particles (5–30 nm) on the outer surface of the zeolite, and Ni-Mo alloy particles with different compositions (under reaction conditions, carbon filaments grew on these particles). It was found that, as the Ni content was increased from 0.1 to 2.0 wt %, the rate of deactivation of the catalytic system increased because of blocking pores in the zeolite structure by filamentous carbon up to the formation of condensed coke deposits.

The influence of the nature of anion X in the tetraethylammonium salt [N(C 2 H 5 ) 4 ]X on the selectivity of the formation zeolite beta in the SiO 2 -Al 2 O 3 -Na 2 O-[N(C 2 H 5 ) 4 ]X-H 2 O system under hydrothermal conditions without seed crystals was studied. It was shown that the test anions can be arranged in the following series in terms of the preferential formation of zeolite beta: F − , SO 4 2− , PO 4 3− , (CH 2 COO) 2 2− > HCOO − > (COO) 2 2− , CH 3 COO − ≫ Cl − ∼ NO 3 − ≫ Br − ≫ I − ≫ ClO 4 − . In particular, the fluoride and the anions of polybasic acids facilitate the formation of zeolite, whereas perchlorate, bromide, and iodide ions inhibit its formation. The experiments showed that anions facilitating the formation of zeolite beta make it possible to synthesize zeolite within the same broad range of chemical composition of the reaction mixture as in the case of [N(C 2 H 5 ) 4 ]OH. The reveled classification of anions into groups coincides with their categorization by Samoilov into anions with positive and negative hydration.

Nonoxidative methane conversion into aromatic hydrocarbons on a zeolite modified with nanosized tungsten powder has been studied. The highest methane conversion and the maximum yield of aromatic hydrocarbons are attained on the catalyst containing 8.0 wt % W. The nature and the distribution of the active phases in the W-containing zeolite were investigated by high resolution transmission electron microscopy and energy dispersive x-ray spectroscopy. The deactivation of the W-HZSM-5 catalyst was studied at different stages of methane conversion. The distribution of coke deposits on the surface of the W-HZSM-5 catalyst was determined.

The effects of the tungsten concentration and of the method of tungsten introduction into ZSM-5 pentails with different SiO2/Al2O3 molar ratios on the acidity and the activity of the resulting catalysis in nonoxidative methane conversion into aromatic hydrocarbons are considered. The catalysts obtained from the SiO2/Al2O3 = 40 pentasil and a nanosized tungsten powder are the most active and the most stable. The maximum methane conversion and the highest yield of aromatic hydrocarbons are achieved on the zeolite containing 8.0 wt % tungsten nanopowder.