Petroleum Chemistry (v.58, #10)

Synthesis of Hierarchical MWW Zeolites and Their Catalytic Properties in Petrochemical Processes (Review) by A. V. Shkuropatov; E. E. Knyazeva; O. A. Ponomareva; I. I. Ivanova (815-826).
Approaches to the synthesis of hierarchical MWW zeolites by the pillaring, delaminating, and recrystallization methods are surveyed and systematized. The influence of the characteristic features of the micro–mesoporous structure of MWW on their physicochemical and catalytic properties has been assessed. The results of investigation of the catalytic activity and selectivity of hierarchical MWW zeolites in petrochemical processes are discussed.
Keywords: MWW zeolite; hierarchical zeolite; pillaring; delamination; recrystallization; petrochemical processes

Regeneration of Zeolite Catalyst for Isobutane Alkylation with Olefins by I. M. Gerzeliev; V. A. Temnikova; A. L. Maksimov; S. N. Khadzhiev (827-832).
The reductive regeneration of a PdCaLaHY zeolite catalyst for isobutane alkylation with butylenes has been studied for the process carried out in the reaction–reductive regeneration–reaction mode. It has been found that the composition of regeneration products was identical to the alkylate composition, suggesting the proceeding of mild hydrocracking of hydrocarbon deposits on the catalyst surface. The optimal maximum temperature of catalyst regeneration has been determined using the TGA/DSC method. The catalyst regeneration conditions found to ensure almost complete recovery of the initial activity of the catalyst are as follows: a temperature up to 320°C, pressure of 1.2 MPa, and a hydrogen space velocity of 1000 h−1.
Keywords: alkylation; isobutane; butylenes; alkylate gasoline; high-octane component, heterogeneous catalyst, reductive regeneration

The effect of different binders (aluminum hydroxide (sample K-1), silica gel (sample K-2), pseudoboehmite (sample K-3), a kaolin–silica sol mixture (sample K-4), and a kaolin–aluminum hydroxide mixture (sample K-5)) on the set of the textural, acidic, and catalytic properties of catalysts based on nanocrystalline zeolite Beta has been studied. It has been shown that the introduction of aluminum hydroxide, silica gel, and a kaolin–aluminum hydroxide mixture as binders does not lead to the blocking of the pore structure of the zeolite, while the introduction of pseudoboehmite and a kaolin–silica sol mixture into the catalyst composition leads to a decrease in the micropore volume. Using the NH3 TPD method, it has been found that the use of aluminum hydroxide, pseudoboehmite, and a kaolin–aluminum hydroxide mixture as a binder leads to an increase in the number of acid sites of the catalyst compared with the respective parameter of the original BEA-25 zeolite. The observed changes are attributed to the migration of aluminum from the binder to the zeolite structure to form new acid sites, as evidenced by 27Al MAS NMR data. It has been assumed that an increase in acidity for the K-4 sample is associated with the interaction of silica with the extra-framework aluminum of the Beta zeolite. With respect to activity in the benzene alkylation with propylene, the catalysts can be arranged in the following order: K-1 > K-3 > K-2 > K-5 ≈ BEA > K-4, which correlates with the number of acid sites in the samples. The best process parameters have been achieved in the presence of the K-1 sample exhibiting a stable on-stream behavior for 10 h and providing a selectivity for alkylation products (cumene + DIPB) of 99.7% and a cumene selectivity of 89.7 wt % at 100% propylene conversion.

The activity of 0.1%Pt and 0.35%Pt catalysts supported on iron-pillared Na- and Ca-saturated montmorillonite has been tested in the n-hexane isomerization reaction. It has been found that a decrease in the platinum content to 0.1% leads to the formation of high amounts of diisomeric hexanes and heptanes. The activity of the catalysts has been correlated with their physicochemical characteristics determined by the BET, ammonia TPD, electron microscopy, and Mossbauer spectroscopy methods. The high strength of the proposed catalysts, high yields of C6 and C7 di- and tri-isomers from n-hexane in the presence of catalysts with a low Pt content, the use of available and cheap natural materials, and a fairly high n-hexane conversion suggest that these catalysts can be used in the isomerization of low-octane light naphtha to high-octane isomers.
Keywords: Pt catalysts; iron; pillared montmorillonites; isomerization

Simulation of the Supramolecular Structure of Petroleum Disperse Systems by Kh. M. Kadiev; A. M. Gyul’maliev; M. Kh. Kadieva; S. N. Khadzhiev (849-854).
The formation of predominant structures of supramolecular entities in highly dispersed colloidal systems, the dispersion phase of which is represented by hydrocarbons, has been studied using molecular mechanics (MM+) simulation. The character of structuring in both individual groups of molecules and their mixtures yielding energetically most stable associates of supramolecular structures has been investigated for compounds taken to model paraffinic, naphthenic, and asphaltenic petroleum components. It has been shown that the number of identical molecules (n) in the associates is limited. For example, asphaltene molecules form an associate with an ordered (graphite-like) supramolecular structure at n ≈ 5–10. Consideration of a mixture of three components with regard to the values of intermolecular interaction energy E IMI shows that in colloidal solutions, asphaltenes form a core to which naphthenic and paraffin hydrocarbons are coordinated.
Keywords: petroleum; disperse system; supramolecular structure; molecular mechanics method; asphaltenes

The laws governing the formation of nanoscale iron-containing disperse systems with a dispersed-phase particle size of 2–256 nm have been studied. The main features of the Fischer–Tropsch (FT) synthesis of synthetic hydrocarbons (HCs) in the presence of these systems have been revealed; the effect of the active phase concentration in the slurry on the selectivity for products with the C11+ chain length has been determined. It has been shown that a decrease in the particle size of the disperse system leads to an increase in the resistance of the iron carbide phase to oxidation by oxygen-containing products formed in the HC synthesis reaction.
Keywords: nanoscale dispersions; Fischer–Tropsch synthesis; synthetic hydrocarbons

Ultrasound-Assisted Modification of Zeolite Catalyst for Dimethyl Ether Conversion to Olefins with Magnesium Compounds by E. E. Kolesnikova; T. K. Obukhova; N. V. Kolesnichenko; G. N. Bondarenko; O. V. Arapova; S. N. Khadzhiev (863-868).
The influence of ultrasonic treatment at various stages of modification of ZSM-5 zeolite with magnesium compounds has been studied to obtain a nanosized zeolite and increase the dispersion of the active element. It has been found that the use of sonication at various stages of magnesium incorporation into the zeolite structure alters the texture and acid properties of the catalyst. Using temperature-programmed ammonia desorption and diffuse reflectance infrared spectroscopy, it has been shown that the sonication leads to an increase in the proportion of Brønsted acid sites of medium strength.
Keywords: zeolite catalysts; modification; dimethyl ether; lower olefins; ultrasonic treatment

Selective Catalytic Hydrogenation of Alicyclic Dienes with Hydrogen in a Liquid Phase by M. V. Bermeshev; T. N. Antonova; D. R. Shangareev; A. S. Danilova; N. A. Pozharskaya (869-875).
The hydrogenation behavior of a number of alicyclic dienes (5-vinyl-2-norbornene (5-vinyl-bicyclo[2.2.1]heptene-2), dicyclopentadiene (tricyclo[5.2.1.02,6]decadiene-3,8), and cis,cis-1,5-cyclooctadiene) to the corresponding cycloalkenes in the presence of a finely divided palladium catalyst suspended in the liquid phase has been studied. The reactivities of the double bonds of these dienes have been compared. The conversion of 5-vinyl-2-norbornene and selectivity of its hydrogenation to 2-vinylnorbornane depending on the reaction conditions have been evaluated. Conditions for the selective production of desired 2-vinylnorbornane are proposed for the further implementation of this process in practice.
Keywords: 5-vinyl-2-norbornene; 2-vinylnorbornane; dicyclopentadiene; 1,5-cyclooctadiene; liquid-phase hydrogenation; finely divided catalysts; double bond reactivity

Effect of the Composition of a Nonacid n-Alkane Cyclization Catalyst on Its Physicochemical and Catalytic Properties by A. N. Loginova; S. A. Sviderskii; Ya. V. Morozova; K. B. Rudyak; V. V. Fadeev; I. A. Safatova; E. A. Isaeva (876-883).
Information is presented on the catalysts used for the cyclization of n-alkanes and the features of the relevant reactions, depending on the nature of the binder used for catalyst synthesis. A procedure for the synthesis of nonacid catalysts for the cyclization of n-alkanes is described. The results of instrumental studies and catalytic tests of synthesized catalyst samples are presented. Of the most common commercial binder materials manufactured by SASOL, boehmite Disperal P2 has been found to provide the best combination of mechanical and catalytic properties. The optimum ratio of zeolite KL and the binder in the composition of the n-alkane cyclization catalyst is 70 wt % zeolite and 30 wt % binder. This formulation makes it possible to achieve an optimal combination of mechanical strength and catalytic activity of the catalyst.
Keywords: cyclization; nonacid catalyst; zeolite

The mechanism of synergism for mixtures of phase-transfer carriers QХ with tertiary amines and pyridine in the epoxidation reaction of allyl chloride has been established. It has been shown that tertiary amines (triethylamine, tributylamine, N,N-dimethylaniline, and N-methyldiethanolamine) and pyridine oxidizable in situ to N-oxides promote the transfer of the organic substrate (allyl chloride) to the interface (PB). It is assumed that the synergism of mixtures of phase-transfer carriers QХ with a tertiary amine oxide or pyridine oxide can also be due to the formation of a mixture of two catalysts, Q3[PW4O24] and WO(O2)2L (where L = a tertiary amine oxide or pyridine oxide). The WO(O2)2L complex will provide the stage of reoxidation of the complex Q3[PW4O24 − х ] in the organic phase and, hence, the possibility for the development of the process of epoxidation not only at the interface but also in the bulk of the organic phase. The maximum coefficient of synergistic effect (k s = 2) is observed for a mixture of cetylpyridinium bromide (90 mol %) and pyridine N-oxide (10 mol %).
Keywords: allyl chloride epoxidation; phase-transfer catalysis; phase transfer; interface; epichlorohydrin; phosphorus–tungsten oxo–peroxo heteropoly compounds

Catalytic Condensation of Carbonyl Compounds during the Synthesis of Cyclohexanone in the Production of Caprolactam by E. A. Martynenko; S. V. Levanova; I. L. Glazko; A. A. Morgun (889-894).
Kinetic features of the condensation processes of carbonyl and unsaturated impurities in cyclohexanone have been studied using model mixtures in a heterophase system in the presence and absence of phase-transfer catalysts. It has been shown that linear aldehydes are condensed with cyclohexanone in the heterophase system in the presence and absence of phase-transfer catalysts under mild conditions (30–50°C). Noncarbonyl unsaturated compounds (e.g., 2-cyclohexene-1-ol) can be removed only at temperatures above 100°C in the presence of acidic catalysts (e.g., high-temperature sulfonated cation-exchange resins). Unsaturated cyclic ketones are characterized by both alkylation reactions over acid catalysts and aldol condensation reactions in the presence of an alkali, thereby suggesting the possibility of their elimination at different cyclohexanone purification steps. The theoretical models built can be used to develop an effective cyclohexanone purification technology that will substantially enhance the manufacturability of high-purity caprolactam and polyamide.
Keywords: cyclohexanone; caprolactam; condensation; phase-transfer catalysis

Theory and Practice of the Preparation of Adamantylarenes by S. V. Tarazanov; V. A. Shakun; T. N. Nesterova; V. S. Sarkisova; P. V. Naumkin; I. A. Nesterov; O. V. Repina (895-904).
The adamantylation of diphenyl oxide and phenol with 1-chloro(bromo)adamantanes in a liquid phase has been studied. The reaction has been performed under kinetic control and under the conditions of reaching chemical equilibrium using the following catalysts: Amberlyst 36 Dry, in situ HBr, and AlCl3. The kinetics of isomerization of (1-adamantyl)- and (2-adamantyl)diphenyl oxides has been studied at 333 and 417 K in the presence of AlCl3 and Amberlyst 36 Dry, respectively. The equilibrium of the positional and structural “bridge–bridgehead” isomerization has been studied in the range of 333–523 K. It has been found that high selectivity of the adamantylation of diphenyl oxide or phenol can be achieved in the case of the use of sulfonated cation-exchange resins as a catalyst. In the presence of aluminum halides or HBr, the reaction mixture has been represented by all the possible isomers and adamantane.
Keywords: isomerization; kinetics; chemical equilibrium; adamantane; sulfonated cation-exchange resins; acids

The basic features of purification of the butylene–butadiene fraction for the removal of acetylene hydrocarbons by catalytic hydrogenation in industrial reactors have been studied. It has been shown that the use of gas distributor nozzles to deliver hydrogen with a flux spread of no more than 10% makes it possible to reduce butadiene losses to 1.2 wt % and to decrease the hydrogen/(acetylene hydrocarbons) molar ratio from 6.8 to 3.8.
Keywords: catalytic hydrogenation; butylene–butadiene fraction; butadiene-1,3; gas distributor nozzles