Petroleum Chemistry最新文献

A series of bifunctional cobalt composite catalysts supported on mixed zeolites were synthesized to enhance the selectivity towards liquid fuels rich in branched hydrocarbons. Given that the catalysts were prepared with an alumina binder and that the mixed zeolites consisted of two molecular sieves, the finished samples were generally formulated as Co–Al₂O₃/SiO₂ + [ZSM-5 + (ZSM-23, Beta, SAPO-11)] + Al₂O₃. The catalysts were tested in Fischer–Tropsch synthesis at 240°C, 2.0 MPa, an H₂/CO ratio of 2 : 1, and a syngas hourly space velocity (GHSV) of 1000 h^–1. The catalyst supported on ZSM-5+Beta exhibited the highest selectivity towards C₅–C₁₀ hydrocarbons. The ZSM-5+ZSM-23-supported catalyst turned out to be the most selective towards branched hydrocarbons, which, in turn, favored the production of a diesel fraction with optimal low-temperature properties.

The physicochemical properties and group composition of crude oil from the Tailakovskoye oil field were examined. As the temperature was lowered from 50 to 10°C, the structural and mechanical properties of the 20, 40, 60, and 70% water-in-oil emulsions (WOEs) of this oil were characterized and investigated. The mean molecular weights and spectral characteristics were evaluated for the resins and asphaltenes isolated both from the crude oil under study and from the stabilizing layers of the emulsions. The average molecule of the stabilizing layer asphaltenes was found to have a higher molecular weight than that of the parent oil asphaltenes. It was further shown that the WOE viscosity abruptly increases with rising water cut, especially at low temperatures: at 10°C the viscosity of the 70% WOE exceeded that of the parent crude oil by a factor of over 50. This is associated with the strengthening of the protective interfacial films surrounding water droplets. The emulsion stabilizers were found to mainly consist of asphaltenes. IR spectroscopy showed that the asphaltenes isolated from the stabilizing layer had a greater content of condensed and aliphatic moieties than the resins and asphaltenes from the parent crude oil. Finally, the effect of ultrasonic treatment on the dispersion of the WOEs was investigated for different water contents. The greatest sonication effect was observed for the WOEs with high water cuts.

The effect of hydrogen donors, tetralin and 1-propanol, and of the Ni–Fe catalyst in combination with 1-propanol on the thermal degradation of the organic matter of the carbonate–siliceous rock from the Romashkino field with 7.07% C_org content in supercritical water at 374°С and pressures from 18 to 24 MPa was revealed. 1-Propanol, compared to tetralin, influences the kerogen degradation in supercritical water more efficiently and suppresses the coking. The degradation of alkyl chains of the organic matter to form saturated hydrocarbons occurs in the presence of 1-propanol most intensely. Introduction of 1-propanol into the reaction system in combination with the Ni–Fe catalyst initiates the kerogen degradation to liquid petroleum fractions to a lesser extent but activates the condensation leading to the formation of large amounts of carbenes/carboids and coke. Depending on introduction of various additives into the reaction system, the most significant differences are observed in the structural-group composition of resins in which the ratio of the СН₃/СН₂ groups decreases and the content of oxygen-containing S=O, С=О, and О–Н groups increases as the extent of condensation of their structure decreases. In contrast to resins, the degree of aromaticity and degree of condensation of asphaltenes increase owing to an increase in the number of hydrogen atoms in the structure of the rings. A common trend for asphaltenes and resins in all the experiments is an increase in the content of hydroxyl О–Н groups. The carbenes/carboids are characterized by relatively low content of aliphatic CH₂ and CH₃ groups and oxygen-containing СО groups and by high degrees of aromaticity and condensation of their structure.

Nickel, cobalt, molybdenum, tungsten, and iron phosphides were prepared in situ from oil-soluble precursors and red phosphorus in the presence of a chlorinated substrate, 1,4-dichlorobenzene. Their catalytic activity was studied in competing processes of the hydrogenolysis of model feedstock containing a chlorinated derivative (1,4-dichlorobenzene) and heteroatomic compounds (benzothiophene, guaiacol, terephthalic acid, quinoline). Analysis of the phase composition of the catalysts by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) confirmed the formation of the phases of the metal phosphides, chlorides, and phosphates. The activity of the phosphides in the 1,4-dichlorobenzene hydrodechlorination increases in the order Mo < Fe < W < Co < Ni, and that in the joint process of 1,4-dichlorobenzene hydrodechlorination and benzothiophene hydrodesulfurization, in the order Co < W < Fe ≈ Ni < Mo. In the hydrodechlorination of 1,4-dichlorobenzene in a mixture with guaiacol, the activity of all the phosphides except iron phosphide decreases as compared to the 1,4-dichlorobenzene hydrodechlorination in the single-component system. Iron phosphide shows promise as a protective bed catalyst in the hydrotreating of polymer waste pyrolysis products, and nickel phosphide, as a catalyst for the hydrotreating of products formed by pyrolysis of polyvinyl chloride in polymer waste mixtures.

The paper describes the physicochemical characterization and catalytic testing of MFI zeolites (both parent and P-modified) with crystal sizes varying from 0.15 to 6 μm. Their physicochemical properties were examined by X-ray diffraction analysis, X-ray fluorescence analysis, scanning electron microscopy, low-temperature nitrogen adsorption, IR spectroscopy, and ²⁷Al and ³¹P MAS NMR spectroscopy. Both the parent and P-modified MFI zeolites were then tested in toluene disproportionation. In the case of parent zeolites, a 15-fold reduction in the crystal size doubles toluene conversion but has no effect on p-selectivity. Phosphorus modification reduces the concentration of acid sites in the samples. In this case, increasing the crystal size to 3–6 μm enhances the p-selectivity up to 78.2%.

NiMo sulfide catalysts supported on zeolites of various structural types were prepared by incipient wetness impregnation. The materials, supports, and catalysts based on them were characterized by low-temperature nitrogen adsorption, energy-dispersive X-ray fluorescence analysis, Fourier IR spectroscopy of adsorbed pyridine, and transmission electron microscopy. The catalytic properties of the systems in the hydrodeoxygenation/hydroisomerization of the triglyceride feedstock were studied using a fixed-bed flow-through reactor at T = 280–340°С, P = 4 MPa, hydrogen to feed ratio H/F of 600 nl/l, and liquid hourly space velocity LHSV of 1–2 h^–1. For all the catalytic systems irrespective of the support type, the degree of deoxygenation reaches 100%, and at T = 320°С and LHSV = 1 h^–1 the relative content of alkane isomerization products decreases in the order NiMoS/A (SiO₂/Al₂O₃ = 30) > NiMoS/B (SiO₂/Al₂O₃ = 300) > NiMoS/D (SiO₂/Al₂O₃ = 30) > NiMoS/C (SiO₂/Al₂O₃ = 48).

A high-copper CuO/ZnO/Al₂O₃ catalyst was synthesized by the oxalate technique. The catalyst prepared in this manner was distinguished by a narrow mesopore size distribution (3.5–8.5 nm) as well as by well-developed specific and active surface areas (140 and 95 m²/g, respectively). Its catalytic activity and selectivity were tested in a flow-type setup under near-industrial process conditions. A variety of characterization methods such as X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), low-temperature nitrogen adsorption, and chemisorption analysis were used to identify the composition and physicochemical properties of the catalyst. The data obtained demonstrate the catalyst’s high performance in processing CO-rich gas mixtures. An investigation of the process selectivity at 210°C showed that methanol is the predominant byproduct and that its concentration correlates with the CO concentration in the gas feed. In terms of catalytic performance, the synthesized catalyst is comparable to its available commercial counterparts.

CoMo sulfide catalysts supported on an MCM-41-type ordered mesoporous silica and on a hierarchical aluminosilicate material based on halloysite nanotubes (MCM-41@HNT) were synthesized by incipient wetness impregnation. Both the supports and related catalysts were characterized by low-temperature nitrogen adsorption–desorption, energy dispersive X-ray fluorescence analysis, FTIR spectroscopy of adsorbed pyridine, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalyst samples were further tested in hydrodesulfurization of 4,6-dimethyldibenzothiophene. The MCM-41@HNT-supported catalyst exhibited the greatest activity in the main reaction (hydrodesulfurization) due to its hierarchical porous structure and the presence of high-temperature Brønsted acid sites.

A series of SAPO-11 and SAPO-41 molecular sieve samples were synthesized using two different aluminum sources. The physicochemical properties of the samples were characterized, and their catalytic performance was tested in hydroisomerization of n-hexadecane. The effects of the aluminum source on the morphology and size of SAPO-11 and SAPO-41 crystals were identified. Specifically, the SAPO-11 and SAPO-41 samples synthesized using aluminum isopropoxide were found to have a higher specific surface area and a higher mesopore volume than their counterparts prepared with boehmite as an aluminum source. It is further shown that SAPO-11 and SAPO-41 samples with similar acidity and similar porosity characteristics exhibit comparable catalytic performance in hydroisomerization of higher n-paraffins.

Catalytic properties that mesoporous amorphous titanosilicate catalysts differing in physicochemical characteristics exhibit in cyclohexene oxidation with hydrogen peroxide to a mixture consisting mainly of alcohol and ketone were studied. The cyclohexene conversion and selectivity of formation of oxidation products depend both on the physicochemical properties of the titanosilicates studied (nature of active sites, porosity, etc.) and on the reaction conditions. The total selectivity with respect to the enol + enone fraction of 94% at the maximal cyclohexene conversion of 55% was reached in the presence of TSMa titanosilicate (Si/Ti = 40).