Petroleum Chemistry (v.56, #1)

Physicochemical aspects of petroleum coke formation (review) by V. M. Kapustin; V. F. Glagoleva (1-9).
The current status and development of petroleum residue upgrading via coking in Russia and over the world have been surveyed with an emphasis on the role of the process in salving the problem of increasing the refining depth. Theoretical concepts of thermal conversion of heavy petroleum feedstock and the structure of asphaltenes as principal coke-forming compounds have been discussed, the results of studies on the formation of coke as either a byproduct or (to a greater extent) the desired product have been considered, and models of the coke structure have been proposed. The characteristic features of the coking process for petroleum residues of various chemical compositions have been addressed, as well as means for controlling the feedstock thermal stability and the yield and quality of coke with the use of external factors.
Keywords: oil refining depth; petroleum coke; heavy residual feedstock; asphaltenes; supramolecular structures; resistance to phase separation; thermal conversion; coke structure

Chemolysis of ether/ester and sulfide bonds in the molecules of high- and low-molecular-weight asphaltenes of heavy crude oil from the Usa oil field has been performed, and the composition of the liquid products of their cleavage has been studied. It was found that the core of the molecules of both fractions of asphaltenes is bound with alkanes, cycloalkanes, aromatic hydrocarbons, and heteroatomic organic compounds via ether/ester and sulfide bridges. High-molecular-weight asphaltenes of oil from the Usa oil field are characterized by a higher proportion of “sulfur-bound” structural elements. Compounds bound by ether/ester groups contribute substantially to the structure of the low-molecular-weight asphaltenes.
Keywords: asphaltenes; chemolysis; saturated and aromatic hydrocarbons; heteroatomic organic compounds; heavy oil

Concentrations of vanadium and nickel and their ratio in heavy oil asphaltenes by M. R. Yakubov; D. V. Milordov; S. G. Yakubova; D. N. Borisov; V. T. Ivanov; K. O. Sinyashin (16-20).
Trends in the vanadium and nickel concentrations in asphaltenes of heavy oils from different oilfields, in which the total content of these metals vary from 0.0049 to 0.1795 wt %, have been studied. It has been shown that as the vanadium and nickel content in heavy oils increases, vanadium concentrates faster than nickel in asphaltenes. In heavy oils, asphaltenes contain approximately 40–90% of total vanadium and 25–75% of total nickel. The summed concentration of vanadium and nickel in heavy oil asphaltenes can reach 1 wt %.
Keywords: vanadium; nickel; heavy oil; asphaltenes; resins

Influence of rock-forming and catalytic additives on transformation of highly viscous heavy oil by S. M. Petrov; D. A. Ibragimova; Ya. I. I. Abdelsalam; G. P. Kayukova (21-26).
The influence of the rock-forming additives kaolin and alumina in the presence of nickel compounds on the thermal catalytic conversion of heavy oil at a temperature of 360°C in a reducing atmosphere at different pressures in the system has been revealed. The effect of poly-α-olefins as a hydrogen donor has been examined. It has been found that there are predominant degradation reactions of the resinous components, aliphatic substituents in asphaltenes, and branched aliphatic structures accompanied by redistribution of n-alkanes toward homologues with a lower molecular weight, resulting in reduction in the viscosity of heavy oil. Conducting the process in the presence of Al2O3, Ni, and poly-α-olefins at a pressure of 8 MPa increases the quantity of light fractions of the oil and facilitates the degradation of asphaltenes. A decrease of pressure in the experiment on the oil with kaolin in a reducing atmosphere leads to a decrease in aromaticity of the final product and an increase in the yield of lube oil hydrocarbon and low-boiling fractions.
Keywords: heavy oil; carbonate additive; kaolin; aquathermolysis; bulk composition; molecular weight distribution of n-alkanes

Palladium hydrogenation catalysts based on nanodiamonds and activated carbon with a metal content of 1 wt % have been studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). It has been shown that the nature of the support has an effect on the electron binding energy of palladium and the stability of metal sites formed during supporting. The resulting catalysts exhibit activity in the model nitrobenzene and cyclohexene hydrogenation reactions under mild conditions (T = 318 K; $${P_{{H_2}}}$$ = 0.1 MPa; solvent, ethanol); the nanodiamond-based catalyst is significantly more active and efficient than the counterpart based on activated carbon.
Keywords: nanodiamonds; activated carbon; catalysts; hydrogenation; scanning electron microscopy; X-ray photoelectron spectroscopy

Isomerization of n-hexane on binder-free shaped platinum-containing mordenite by O. S. Travkina; R. Z. Kuvatova; I. N. Pavlova; Ahmed Kanaan Ramadan; A. F. Akhmetov; B. I. Kutepov (33-37).
A catalyst has been prepared as binder-free shaped MOR-type zeolite in the H form promoted with 0.5 wt % platinum, and n-hexane conversion over this catalyst has been studied. It has been found that the selectivity for C4–C6 isoparaffins on the new catalyst is about 90% at 300°C, a feed space velocity of 1.5 h–1, and a hydrogen pressure of 3 MPa, with the hexane conversion being 80.0–83.0 wt % and the selectivity for isohexane making 83.0–86.0%. It has been shown that the new catalyst is stable for 50 h on-stream under these conditions.
Keywords: MOR type zeolite; pellets; catalyst; isomerization; n-hexane

Features of dicyclopentene formation during hydrogenation of dicyclopentadiene by N. V. Vereshchagina; T. N. Antonova; A. A. Il’in; Zh. V. Chirkova (38-43).
General trends and specific features of the reaction of dicyclopentadiene (tricyclo[5.2.1.02.6]decadiene-3,8) hydrogenation to dicyclopentene (tricycle[5.2.1.02.6]decene-3) with hydrogen in the liquid phase under mild conditions at atmospheric pressure over a finely divided 1% Pd/C catalyst have been studied. The kinetic parameters that characterize the effect of the solvent nature, catalyst concentration, and temperature on the rate of hydrogen uptake in the hydrogenation process have been determined. To substantiate the conclusion of the sequence of saturation of the dicyclopentadiene double bonds in terms of the mechanism of heterogeneous catalysis, their reactivity has been compared. It has been shown that in the presence of a number of functionalized aromatic compounds as a stabilizing additive, the yield of desired dicyclopentene increases to 98.5–99 mol % with the complete conversion of dicyclopentadiene. The structure of dicyclopentadiene and its hydrogenation product dicyclopentene has been confirmed using spectroscopic methods.
Keywords: dicyclopentadiene; dicyclopentene; liquid-phase hydrogenation; finely divided catalyst; double-bond reactivity

Synthesis of nickel–tungsten sulfide hydrodearomatization catalysts by the decomposition of oil-soluble precursors by I. A. Sizova; A. B. Kulikov; M. I. Onishchenko; S. I. Serdyukov; A. L. Maksimov (44-50).
Nickel–tungsten sulfide catalysts for the hydrogenation of aromatic hydrocarbons have been prepared by the in situ decomposition of an oil-soluble tungsten hexacarbonyl precursor in a hydrocarbon feedstock using oil-soluble nickel salt nickel(II) 2-ethylhexanoate as a source of nickel. The in situ synthesized Ni–W–S catalyst has been characterized by X-ray photoelectron spectroscopy. The activity of the resulting catalysts has been studied in the hydrogenation of bicyclic aromatic hydrocarbons and dibenzothiophene conversion in a batch reactor at a temperature of 350°C and a hydrogen pressure of 5.0 MPa. It has been shown that the optimum W : Ni molar ratio is 1 : 2. Using the example of the hydrofining of feedstock with high sulfur and aromatics contents, it has been shown that the synthesized catalyst exhibits high activity in the hydrogenation of aromatic hydrocarbons.
Keywords: tungsten hexacarbonyl; oil-soluble precursors; nickel–tungsten sulfide catalyst; dehydrodearomatization; light cycle oil

Catalytic cracking of hydrotreated vacuum gas oil over a zeolite-containing catalyst modified with nickel and cobalt nanoparticles by I. M. Gerzeliev; R. M. Arslanov; V. M. Kapustin; G. N. Bondarenko; S. N. Khadzhiev (51-55).
The effect of the concentration of nickel and cobalt precursors on the catalytic cracking performance has been studied. A FTIR study of the catalyst surface after cracking in the presence of nickel and cobalt precursors has been conducted. It has been shown that the surface of industrial catalysts can be in situ modified with compounds of Group VIII metals in the acid-catalyzed conversion of a vacuum distillate.
Keywords: catalytic cracking; hydrotreated vacuum distillate; nickel; cobalt; FTIR analysis

Co-hydrotreating of straight-run diesel fraction and vegetable oil on Co(Ni)-PMo/Al2O3 catalysts by P. A. Nikul’shin; V. A. Sal’nikov; Al. A. Pimerzin; Yu. V. Eremina; A. S. Koklyukhin; V. S. Tsvetkov; A. A. Pimerzin (56-61).
The process of co-hydrotreatment of straight-run diesel fraction (DF) and vegetable oil (VO) on Co(Ni)-PMo/Al2O3 catalysts prepared from H3PMo12O40 and cobalt (nickel) citrate has been studied. It has been shown that under conditions close to those in the industry, the complete conversion of fatty acid triglycerides (FATG) is achieved on the catalysts of both types to give an ultraclean hydrotreating product in a 97% yield and a cetane number of 5 points above that of the hydrotreating product of the DF alone. The degree of hydrodesulfurization (HDS) is reduced more significantly on the Co-PMo/Al2O3 catalyst than in the case of Ni-PMo/Al2O3. The catalysts are more susceptible to deactivation in the hydrotreating of the blended feedstock containing VO. The Co-PMo/Al2O3 sample is less stable than Ni-PMo/Al2O3. Examination of the spent catalysts by transmission electron microscopy has shown that the average particle length of the active phase of Co-PMo/Al2O3 increases, whereas this increment for Ni-PMo/Al2O3 is insignificant, indicating higher stability of particles of the NiMoS phase. Thus, the co-hydrotreating of petroleum fractions and vegetable oil is more reasonable to carry out on NiMo/Al2O3 catalysts.
Keywords: co-hydrotreating; straight-run diesel fraction; hydrodesulfurization; hydrodeoxygenation; vegetable oil; NiMoS; CoMoS

Cyclododecene cometathesis with hexene-1 on the MoCl5/SiO2–Me4Sn catalytic system by V. I. Bykov; B. A. Belyaev; T. A. Butenko; E. Sh. Finkel’shtein (62-64).
The stereochemistry of the cometathesis of cyclododecene (CDD) with hexene-1 in the presence of the MoCl5/SiO2–Me4Sn heterogeneous catalytic system has been studied. It has been established that CDD is the mixture of cis- (Z) and trans- (E) stereoisomers with the ratio of 30/70, respectively. It has been shown that the reactivity of the E-stereoisomer of CDD in the reaction of cometathesis is higher when compared to the Z-stereoisomer. Thus, when the conversion of CDD is 92%, the ratio E/Z = 6 : 94, i.e., the amount of the E-stereoisomer decreases from 70 to 7%, while the amount of the Z-stereoisomer increases from 30 to 93%, respectively.
Keywords: stereochemistry; cometathesis; cyclododecene; heterogeneous catalysis

Improvement in the viscosity characteristics of boiler oil by additives by E. R. Zvereva; G. R. Mingaleeva; R. V. Khabibullina; G. R. Akhmetvalieva (65-67).
The viscosity of a mixture of fuel oil with the liquid additive Diproxamine and a solid additive based on the carbonate sludge of water treatment has been experimentally studied. It has been found that these additives affect the viscosity characteristics of fuel oil. The economic efficiency of automated systems for dispensing the solid and liquid additives in fuel oil has been evaluated.
Keywords: fuel oil; dynamic viscosity; shear rate; non-Newtonian fluid; Diproxamine additive; carbonate sludge; automatic dosing system

Poly(alkyl (meth)acrylate) depressants for paraffin oils by O. A. Kazantsev; G. I. Volkova; I. V. Prozorova; I. V. Litvinets; D. V. Orekhov; S. I. Samodurova; D. M. Kamorin; A. A. Moikin; A. S. Medzhibovskii (68-72).
The peculiarities of synthesis of higher poly(alkyl (meth)acrylate)s bearing C16–C26 alkyl fragments are considered, and a comparison of their functioning as depressants for paraffin oils from different deposits is carried out. It is shown that the highest efficiency in oils under study is manifested by the sample of C16–C20 poly(alkyl acrylate) with a weight-average molecular mass of 70000.
Keywords: (meth)acrylic acid; higher fatty alcohols; esterification; alkyl (meth)acrylates; radical polymerization; depressants; oils

The anticorrosion properties of hexamethylenetetramine, boric acid, and a mixture of individual polyethylene polyamines have been investigated, as well as the dependence of steel corrosion rate in inhibited hydrochloric acid on the molar ratio of the components, reaction temperature, and synthesis time. The optimal molar ratios of boric acid, polyethylene polyamines, and hexamethylenetetramine and synthesis time and temperature have been determined. It has been shown that boric acid can be used as a component of the active base of a corrosion inhibitor. The use of boric acid is due to the synergistic effect of the test components of the active base and a low cost and nonhazardous nature of the material.
Keywords: corrosion inhibitor; polyethylene polyamine; boric acid; degree of protection