Petroleum Chemistry最新文献

Mixed sulfided CoMo catalysts supported on γ-Al₂O₃ and halloysite nanotubes (HNTs) were synthesized by incipient wetness impregnation with salt solutions of Keggin-type phosphorus- and vanadium-containing heteropolyacids. The synthesized materials were characterized by low-temperature nitrogen adsorption, energy dispersive X-ray fluorescence analysis, temperature-programmed reduction (both for the oxide and sulfide catalysts), and Raman spectroscopy, and were tested in hydrogenation of naphthalene and hydrodesulfurization of dibenzothiophene. The HNT-supported catalyst exhibited a greater activity in these reactions.

This review discusses the theoretical basis and examples of implementation of various molecular modeling approaches to the investigation of the properties of surfactants. These surfactant properties include the ability to reduce the interfacial tension and alter the wettability and viscosity of solutions for the purposes of chemical flooding of crude oil reservoirs. A comparative analysis of the advantages and disadvantages of the existing molecular dynamics simulation methods is further provided. It is shown that molecular modeling methods can significantly facilitate the choice of surfactants for specific oil field conditions and can serve as a potential alternative to experimental measurements.

Regular trends in the distribution of hydrocarbon biomarkers (n-alkanes, isoprenanes, steranes, and terpanes) and hydrocarbons of the adamantane series in low-maturity crude oil from the Anastasievsko-Troitskoe oil field (horizon IV) and in products formed by thermolysis of asphaltenes, resins, and acids from this oil were studied by gas chromatography–mass spectrometry. Thermolysis of high-molecular-mass oil precursors yields the same hydrocarbons (HCs) as those present in the initial oil, and also protoadamantanes (precursors of adamantanes). HCs of the adamantane series are not formed, and their presence in this crude oil is due to their supply from other oil source strata. The experiments show that the n-alkanes present in the initial oil in small amounts are released under more severe conditions.

The study investigates interactions between palladium and silver in Pd–Ag bimetallic catalysts supported on a mesoporous carbon material Sibunit and, in particular, the dependence of these interactions on the deposition sequence of the metal precursors. Using XRD and TEM results, it was shown that impregnating the support with an aqueous solution that contained nitrate salts of both metals, followed by hydrogen treatment at 500°C, generates uniformly sized Pd_0.6Ag_0.4 particles (d_av = 5.6 nm). These particles exhibit high selectivity (79%) in the reaction of acetylene hydrogenation to ethylene. The catalysts synthesized by sequential impregnation of the support with solutions of Pd and Ag nitrates interleaved with heat treatment in H₂ exhibited a lower selectivity (68–73%) due to the formation of particles non-uniform both in composition and size (about 4 to 60 nm). The IR spectroscopy data suggest this effect is presumably associated with the removal of O-containing functional groups from the carbon surface during the reduction of the supported precursor. Given that O-groups act as anchoring sites for the precursors of active components and suppress the ability of Sibunit to reduce metals from their salt solutions, the subsequent deposition of the second metal salt causes a non-uniform distribution of this metal on the surface and the generation of larger particles.

The results obtained in the second part of the study of vicinal (tert-butoxy)alkanols as additives to automobile gasolines are presented. Mono-tert-butyl ethers of ethylene glycol (ETBE) and 2,3-butanediol (BTBE) were prepared by direct acid-catalyzed alkylation of the corresponding diols with tert-butanol. The substances obtained were characterized by main physical properties (density, viscosity, boiling point, crystallization point, specific heat of combustion) and were studied as additives to automobile gasolines. The effect of ether additives on the main physicochemical properties of gasolines (fractional composition, saturated vapor pressure, concentration of actual resins, knock resistance), including ethanol-containing gasolines, was studied. The mean research/motor blending octane numbers for ETBE and BTBE were 130/103 and 115/97, respectively. Inclusion of ETBE/BTBE into the formulations of ethanol-containing gasolines allowed the cloud point to be considerably reduced without unambiguous synergistic effect on the knock resistance.

This study investigated, for the first time, the effects of the tropical climate of Vietnam on the properties of synthetic greases with urea thickeners. The greases were exposed to seven-month field tests at climatic test stations of the Joint Russian–Vietnamese Tropical Research and Technological Center in three regions of Vietnam. This short-term exposure decreased the ultimate strength and affected the colloidal stability of the samples (in the colloidal stability measurements, the amount of separated oil was reduced). At the same time, the chemical composition of the greases remained essentially unchanged, as confirmed by IR spectroscopy. It would be reasonable to assume that the degradation of polyurea greases in tropical climates is primarily associated with their colloidal structural changes. This assumption, however, requires confirmation in further research that should involve longer exposure and a larger number of grease samples prepared from different base oils. It was additionally found that introducing a heterogeneous modifier into polyurea greases impairs their stability in tropical climate.

Abstract

The study investigates the activity of in situ synthesized suspensions of nickel-promoted molybdenum disulfide particles in the hydroconversion of crude oil vacuum residues. The catalyst suspensions were prepared in situ from water-in-oil emulsions of aqueous solutions of precursors, specifically ammonium paramolybdate and nickel nitrate. The catalytic tests were carried out in a flow-type reactor at 430°C, WHSV 1 h^–1, and 7 MPa hydrogen, with the Mo:Ni atomic ratio in the catalyst particles ranging from 1:0.022 to 1:1.43. The XRD of the toluene-insoluble solids (TIS) extracted from the hydrogenates identified sulfides such as MoS₂, Ni₃S₄, and Ni₃S₂ in the dispersed catalyst. Increasing the nickel content in the catalyst favored its hydrogenation activity, which was indicated by an enhancement in the feed conversion, an increase in the content of paraffins and naphthenes, and a decrease in the sulfur content in the distillates and TIS derived from the hydrogenates. The conversion of high-molecular-weight feed components (resins, asphaltenes, and heavy aromatics) was enhanced as a result of the nickel promotion of the dispersed MoS₂.

Abstract

This paper reviews the research background and significance of foam drainage agents, foaming and foam stability mechanisms, and analyzes the advantages and drawbacks of conventional foam drainage agents. With the development of natural gas applications, the exploitation of gas fields becomes more stringent. A new type of foam drainage agent characterized by a wide applicability should be developed based on the particular needs of gas wells. A new foam drainage agent not only resolves the deficiency of conventional foam drainage agents, but also deals with the problem of high costs. It has a higher foam stability and provides a standard for the further design of special conventional and unconventional foam drainage agents for gas fields. Moreover, the polymer addition dramatically improves the performance of foam drainage agents. A Gemini surfactant opens up a new possibility for foam drainage agents. The use of nanoparticles provides the further enhancement of the foam stability for different types of gas reservoirs. The future application trends for foam drainage agents are also discussed. A low-cost and environmentally friendly natural gas promoting a low-carbon green energy, should be developed and used. Highly efficient, environmentally-friendly and recyclable low-cost foam drainage agents would become a hotly debated research point.

Abstract

Although the quality of coal tar does not meet the demands for blended marine fuel, the properties of its components after processing are improved, and they can be considered as inexpensive blending components. Three types of coal tar products including light coal tar I, light coal tar II, and hydrogenated coal tar have been obtained and used in production of residual marine fuels. To minimize costs, a linear optimization method has been used, and all properties of the resulting products have met the required criteria. In addition, a novel analytical method was used to characterize the fuel stability. The analysis of a hydrocarbon composition and a mechanism of interaction between the resin and asphaltene have shown the main coal tar components affecting fuel oil stability are polycyclic aromatic hydrocarbons (PAHs) and resin. A condensation of PAHs and resin into asphaltene and an increasing complexity of asphaltene structure causes deposition of oil products under heating. Hydrogenation is able to effectively reduce the PAH content and the volume of formation of massive asphaltenes thus preventing fuel flocculation and deposition during aging in fuel tanks.

Abstract

The composition of hydrocarbon gases formed by pyrolysis of residual Domanik shale kerogen at 800°C, preceded by hydrothermal treatment at 250–375°С, was studied by pyrolytic gas chromatography. Starting from the autoclave temperature of 320–325°C, the hydrothermal treatment of the shale affects the kerogen structures responsible for the formation of C₂₊ gases in pyrolysis at 800°C. An increase in the temperature of the shale hydrothermal treatment leads to a monotonic increase in the С₁/С₂₊ ratio in the products of the residual kerogen pyrolysis at 800°C. The methane yield at 800°C does not correlate with the content of alkyl structures, determined in kerogen by IR spectroscopy, and the yield of С₂₊ gases linearly correlates with the content of alkyl structures.