Petroleum Chemistry最新文献

Though alumina and silica are well-known and widely used supports, they have notable drawbacks, such as the formation of the AlPO₄ phase and inadequate metal–support interactions with nickel phosphide. This study investigates the synergistic effects of silica and alumina on the physicochemical properties and catalytic performance of nickel phosphide catalysts. Catalysts supported by alumina (Al₂O₃), silica (SiO₂), and a composite silica-alumina (ASA) have been simultaneously prepared using a straightforward isopyknic co-impregnation method in order to eliminate the influence of preparation conditions. The results indicated that Ni₂P/SiO₂ exhibited poor dispersion, while Ni₂P/Al₂O₃ showed a larger particle size along with the formation of the AlPO₄ phase. The coordination between silicon and aluminum facilitated the reduction of nickel phosphate to nickel phosphide (Ni₂P) and inhibited the formation of AlPO₄. Ni₂P/ASA demonstrated an improved dispersion and smaller particle size. Therefore, a comparative study of the Ni₂P/SiO₂, Ni₂P/ASA, and Ni₂P/Al₂O₃ performance revealed the superior catalytic efficacy of the SiO₂–Al₂O₃ supported Ni₂P in the naphthalene hydrogenation.

This paper proposes a novel approach to the extraction of cluster structures from a ZSM-5 zeolite lattice. The approach involves transforming the zeolite crystalline structure into a directed molecular graph followed by identifying cycles from which cluster structures are generated. One advantage of this approach is the complete similarity of the resultant cluster structures at equal input data, making the DBSCAN clustering method applicable to the identification of unique structures. Furthermore, this approach is effective in identifying the active and extended regions within a multilevel ONIOM model for subsequent quantum-chemical calculations. Finally, the proposed approach makes it possible to automate the extraction of cluster structures from ZSM-5 crystals and to select the most important structures for further analysis. To validate its efficiency, the novel approach was applied to identify the most probable location of Zn²⁺ cation-exchange sites in ZSM-5.

Based on quantum-chemical computation, a solution with periodic boundary conditions (PBC) was employed within density functional theory (DFT) simulations in order to assign the chemical shifts in the ²⁷Al MAS NMR spectra of Al-BEA (HBEA) zeolite (Si/Al = 31) to the individual crystallographic T-sites calculated for polymorph B of an identical zeolite. The results were compared both to relevant published reports (Si/Al = 71 and 75) and to the experimental data previously obtained by the authors for a mixture of polymorphs (Si/Al = 25). Deconvolution of the ²⁷Al MAS NMR spectrum into Al signals at different T-sites of polymorph B was compared to a similar deconvolution for polymorph A.

Two series of zeolites, vis., the MEL and MFI types, with different Si/Al molar ratios were synthesized by a steam-assisted crystallization method, specifically dry gel conversion (DGC). Their physicochemical properties were characterized by low-temperature nitrogen adsorption, scanning electron microscopy, and X-ray fluorescence analysis. The acidic properties were examined by IR spectroscopy of adsorbed pyridine and 2,6-di-tert-butylpyridine as well as by ammonia temperature-programmed desorption. The DGC-synthesized zeolites were distinguished by high crystallinity, small crystal size, and well-developed surface. All the samples exhibited high activity and deactivation resistance in the oligomerization of a butane–butylene fraction. A comparative assessment of the catalytic performance the MEL and MFI samples demonstrated that the structural difference between the MEL and MFI types barely affects their deactivation resistance. Therefore, MEL zeolite is a valid alternative to the MFI type in the development of oligomerization catalysts.

In order to determine the viscosity of liquid and gaseous chlorofluorocarbons, various experimental approaches and graphs have been developed, but they had a limited use. In this study, the viscosity of chlorofluorocarbons and hydrocarbon mixtures has been determined by applying a reliable model based n the Peng–Robinson cubic equation of state and the mixing rule for hydrocarbon mixtures. Finally, the Fminsearch algorithm has been used to optimize the result of 531 data points including 451 points for pure chlorofluorocarbons (167 points for saturated liquid chlorofluorocarbons, 284 points for unsaturated gaseous chlorofluorocarbons (R13, R32) and 80 points for binary mixtures. In this study, a large chlorofluorocarbon data set obtained for a wide pressure (3237–5805 kPa), and temperature (301.84–487.40 K) ranges has been used. The results show a similarity between the experimental data and the model results. For 17 pure chlorofluorocarbons considered in this study, the calculated average absolute deviation is 1.92%, and the average relative error for four two-component hydrocarbon mixtures is 5.28%. A difference between the predicted and the experimental viscosity for R13 and R32 was mainly 0.1. In general, the analyzed model is accurate and does not require the bulk density that represents its main advantage.

Antistatic additives are introduced into diesel and jet fuel formulations to ensure the safety of the fuel transportation and operation. Studying the structure and performance of these additives is of scientific and practical interest. Published data in this field are analyzed in the paper. The analysis shows that modern antistatic additives consist of several functional components of which the anionic component is the most important. In virtually all the formulations, this component is polysulfone, a copolymer of sulfur dioxide and α-olefins. Along with analysis of the published data, five commercial samples of antistatic additives were analyzed by spectroscopy and chromatography. The analysis confirmed critical significance of the polysulfone as an anionic component and allowed determination of the composition and structure of other components of the additive: cationic and acid components and the solvent.

The physical and chemical characteristics of oils from Western Kazakhstan have been studied in relation to their potential as raw materials for producing specialized binders for the road construction within the country. This study includes a detailed description of the features of the principal oil deposits in this region. It has been shown that these existing deposits are capable of meeting the demand for bitumen production. In addition, an assessment comparing the real and recoverable reserves of these oils in terms of the bitumen production has been conducted.

Surfactants are known as potential candidates for enhancing oil recovery by affecting interfacial tension and wettability in different types of oil reservoirs including sandstones and carbonates. The performance of these agents, may be improved (in terms of stability and activity) by addition of nanoparticles. In this study, titanium dioxide (TiO₂) and silica (SiO₂) nanoparticles taken at different concentrations, were combined with two types of surfactants including cetyltrimethylammonium bromide (CTAB) and arabic gum (GA) and evaluated as the agents providing an enhanced oil recovery in a carbonate oil reservoir in Iran. The CTAB + SiO₂, CTAB + TiO₂, GA + SiO₂, and GA + TiO₂ combinations were analyzed in terms of stability (zeta potential test), surfactant adsorption (UV-visible analysis, interfacial tension (IFT), and rock wettability alteration), and oil recovery (spontaneous imbibition experiment). TiO₂ nanoparticles improved the stability of surfactant suspensions. Moreover, they reduced adsorption of surfactants on a crushed carbonate powder. The visualization of the water film thickness in the presence of oil and rock powder confirmed that the addition of nanoparticles modified the wettability to be more water-wet. In addition, the GA + TiO₂ combination was proved to be the most effective in enhancing the oil recovery in the studied carbonate oil reservoir, showing a significant increase (up to 17%) compared to other studied suspensions in the spontaneous imbibition processes.

The regeneration (purification) of waste oils for their subsequent reuse or for preparation of other kinds of lubricants (e.g., greases) is an essential step in the closed loop of petroleum products. Numerous approaches to waste oil valorization are known today. The use of membranes for waste oil treatment has a number of advantages and is an actively developing field of science and engineering. This review discusses the latest achievements in the use of membranes for reprocessing waste motor oils, taking into account their chemical composition and physicochemical characteristics influencing the membrane performance.

The paper describes the physicochemical characterization and catalytic testing of MFI zeolites with different SiO₂/Al₂O₃ ratios synthesized by steam-assisted crystallization (SAC) and modified with phosphorus (4 wt % loading). Their physicochemical properties were characterized by X-ray diffraction analysis, X-ray fluorescence analysis, scanning electron microscopy, low-temperature nitrogen adsorption, ammonia temperature-programmed desorption, and MAS NMR spectroscopy. Both the parent and P-modified MFI zeolites were then subjected to catalytic tests in cracking of n-dodecane. The yield of light olefins was enhanced only in two cases: when MFI zeolites with SiO₂/Al₂O₃ ratios of 30–70 were modified with 4 wt % phosphorus and when parent MFI zeolites with SiO₂/Al₂O₃ ratios of 100–220 were used. It was further found that, in terms of catalytic performance in the cracking of n-dodecane, the MFI zeolites synthesized by SAC were comparable to a commercially available MFI zeolite synthesized under hydrothermal conditions. Moreover, in contrast to the commercially available zeolite, phosphorus modification of the SAC-synthesized zeolite enhanced the yield of C₂–C₄ olefins.