Petroleum Chemistry最新文献

While drilling an oil well, the bit will penetrate different geological formations, and these formations will contaminate the drilling fluid either through rocky crumbs or formation water. The amount of alternation caused in the drilling fluid depends on the lithological type of the drilled formation and the percentage of ions in the formation water. Water is the main component of drilling mud, especially water-based mud, and it can be fresh water or salt water. One of the most important duties of the mud engineer when preparing drilling mud is to do a water test to measure the salinity: chloride (Cl^–) and calcium (Ca²⁺). This study relied on field information for oil well in southern Iraq, which was adopted as a model for this case study. The study concluded that the presence of some ions in drilling mud such as Cl, sodium (Na) and Ca either reduces or increases the rheological properties of the mud system and in turn affects the rate of penetration, and it could also lead to serious drilling problems. The results proved that one of the most important indicators of mud contamination is a rise in the proportions of magnesium (Mg), Ca, carbonate (H₂CO₃) bicarbonate (HCO₃), in addition to a low potential hydrogen (H). The rheology of the mud was also affected by contamination, depending on the type of ion polluting the drilling mud and the amount of its percentage. On the other hand, neglecting the treatment and monitoring of mud properties lead to serious problems. The results showed that adding silica dust contributed to treating drilling mud contaminated with calcium ions by 20%, as an increase in the value of the mud’s viscosity was observed after adding silica. When the concentration of sodium chloride (NaCl) was about 8% or less, an increase in the rheological properties of the clay was observed, and the opposite was observed at concentrations of 10% or more.

The stability index of petroleum disperse systems can be calculated using continuous scanning of the optical profile of the asphaltene precipitation, taking into account the induction period of the asphaltene particle aggregation under the preset external conditions. Modification of the ASTM D7061 procedure allows taking into account the induction period of the asphaltene aggregation and different aggregation mechanisms (diffusion- and reaction-limited aggregation). This opens prospects for improving the procedures for express analysis of asphaltene-containing dispersions in the future. The control of the stability of asphaltene-containing systems is the base element for developing of a mathematical model of the kinetics of chemical processes occurring in a stratum, pipeline, or reactor.

Chemical degradation and chromatography–mass spectrometry methods were employed to identify resin components interlinked via ester, ether, and sulfide bridges. The resins were preliminarily isolated from liquid products prepared by thermolysis, at 300 and 450°C, of high-resin heavy oil asphaltenes from the Usinskoye oil field. Unlike the resins isolated at 300°C, their 450°C counterparts predominantly contained compounds that consisted of heteroatoms (i.e., S, N, and O). The particular distribution of bound moieties in the resin samples isolated at these thermolysis temperatures likely indicates that the Usinskoye field heavy oil asphaltenes consist of molecules that vary both in the type and location of ester, ether, and sulfide bridges.

Abstract

Two samples of PdAg/Al₂O₃ egg–shell single-atom catalysts, with Ag/Pd ratios of 1 : 1 and 3 : 1, were synthesized and characterized by TEM, XPS, and DRIFTS-CO methods. The formation of bimetallic PdAg alloy nanoparticles with single-atom Pd₁ active sites was demonstrated. Furthermore, a physicochemical characterization showed a egg–shell distribution of the active component. The catalytic performance of the samples was tested in front-end selective hydrogenation of acetylene. The H₂/C₂H₂ ratio in the model mixture was varied from 20 to 60. Under front-end acetylene hydrogenation conditions, the highest ethylene selectivity (about 87 at 90% acetylene conversion) was achieved in the presence of the Pd₁Ag₃/Al₂O₃ catalyst at H₂/C₂H₂ = 20. Finally, it was shown that, unlike the monometallic Pd catalyst, the Ag-promoted catalysts were completely free of any local thermal runaway effect.

Understanding the value of refinery by-products is crucial for assessing their potential in bitumen production. To achieve this task, the asphaltic residue, vacuum residue, and three different aromatic extracts obtained as by-products in the refining process of base oils have been characterized using various methods, including standard methods for bitumen grading (penetration, softening point, Fraass breaking point, and ageing stability), SARA analysis, proton nuclear magnetic resonance spectroscopy (¹H NMR), and high-performance gel permeation chromatography (HP-GPC). Additionally, the penetration index and three significant colloidal indices based on SARA fractions have been calculated. The results show that the by-products possess distinct properties and chemical compositions. The most striking fact is that the asphaltic residue lacks saturates, while the three aromatic extracts lack asphaltenes. Due to different processing conditions, the two solvent-neutral (SN) type extracts were found to be similar, though distinct from the bright stock (BS) extract, which had a higher content of saturates and a lower content of aromatics. The comprehensive characterization of these by-products (residues and extracts) is essential for understanding their structure and planning their valorization in oil refineries, for example in the production of bitumens with specific properties. When combined with statistical and phenomenological modeling, the systematic analytical procedure presented here is useful for guiding the repurposing of oil refinery by-products.

Abstract

Modification of MFI-type zeolites with tin involves impregnating the zeolite with an SnCl₂ solution in excess NaCl, calcination (to fix the tin oxide), and water washing (to remove excess NaCl). Loading platinum on the tin-modified support results in a highly active (5–10 mol of C₃H₆ per mol of Pt per second), selective (96–98% towards propylene), and stable catalyst for dehydrogenation of propane. Due to the high dispersion of tin, which serves as an anchor for platinum, the average Pt particle size is 1.2 nm. The dispersion of tin is facilitated not only by the molecular dilution of its precursor with sodium chloride but also by the redispersion of tin across the surface due to the formation of volatile SnCl₄ during calcination.

The effects of the p-toluenesulfonic acid monohydrate (TsOH∙H₂O) concentration on the alkoxycarbonylation of cyclohexene over a Pd(PPh₃)₂Cl₂–PPh₃–TsOH∙H₂O catalytic system were quantified at 363–383 K. Within this temperature range, the correlation between the cyclohexyl cyclohexanecarboxylate production rate and the TsOH∙H₂O concentration was found to be similar to an S-shaped curve. Based on these data, as well as previous findings with regard to the effects of water and TsOH∙H₂O concentrations on the cyclohexene methoxycarbonylation rate, the hydride mechanism for the alkoxycarbonylation process was updated by adding relevant ligand exchange reactions between ballast palladium complexes, specifically reactions that produce a palladium aqua complex. The accordingly-modified kinetic equation for cyclohexene alkoxycarbonylation with cyclohexanol and CO was found to be consistent with the experimental data. Effective constants were evaluated for the modified kinetic equation over the studied temperature range. A number of relevant parameters—namely, the effective activation energy and the changes in enthalpy, entropy, and Gibbs free energy during the ligand exchange between the complexes Pd(PPh₃)₂(C₆H₁₁OH)₂ and Pd(PPh₃)₂(H₂O)₂—were further evaluated in light of the activated complex theory. This reaction was found to be nearly equilibrium at 373 K.

This review presents an analysis of the existing concepts for the utilization of electric power for heating chemical reactors, primarily those designed for heterogeneous catalytic processes. The paper provides a brief outline of major electric heating methods in the context of chemical applications, mentions important examples of the industrial implementation of electric heating, and evaluates the prospects for industrial use of electric heating instead of conventional heating systems.

Thermochemical transformations of the organic matter and mineral matrix of the bituminous oil-containing rock from the productive stratum of Permian heavy crude deposits (Ashal’cha oilfield) at 350 and 600°С in a hydrogen medium were studied by electron paramagnetic resonance (EPR) spectroscopy. A rock sample taken from a depth of 117.5–118.5 m was studied before and after hydrothermal treatment at 300°С in the presence of an aqueous phase. Comparison of the EPR spectra shows that, as compared to the initial rock, an increase in the temperature to the “oil window” level, 350°С, leads to a fourfold increase in the intensity of the signal from free organic radicals (С₃₅₀), and after hydrothermal treatment its intensity increases by a factor of 5. This fact characterizes the oil-generation potential of the rock with the formation of liquid and gaseous hydrocarbons. On reaching the “oil and gas window” temperature (600°С), organic carbon radicals (С₆₀₀) were not detected. This fact suggests that the rock from productive deposits of the Permian age virtually completely realizes its oil-generation potential at 350°C. The amount of Mn²⁺ ions in calcite after the hydrothermal treatment gradually decreases with an increase in the pyrolysis temperature. Iron oxides and hydroxides were detected as concomitant compounds. They can exhibit catalytic properties in hydrothermal and pyrolytic processes. The presence of minerals of iron and manganese in different oxidation states suggests nonequilibrium conditions of the rock alteration. Thus, EPR can serve as a nondestructive method for simultaneous monitoring of the mineral composition and organic matter of rocks.

It was shown by EPR spectroscopy that Ti(IV) was gradually reduced to Ti(III) when a titanium(IV) dichloride complex with a saligenin ligand was used as a model pre-catalyst in the presence of (Et_nAlCl_3–n + Bu₂Mg) as an activator. Pre-activation of this complex (by stirring in an inert atmosphere with a half-load of the Al/Mg activator before being introduced into the reactor) significantly (about twofold) enhanced its catalytic activity, up to 4100 kg_PE mol_Ti^–1 h^–1 atm^–1. All the synthesized polyethylene samples were linear ultrahigh-molecular-weight polymers (UHMWPEs) with M_v = 1.0–3.5×10⁶ g/mol. This pre-activation technique was further employed to test a series of Al/Mg activators that differed in the nature of their organometallic compounds and in their Al/Mg molar ratio. The test data suggest that the catalytic system under study had active sites with titanium being present mainly in the oxidation state of +3. Most samples of UHMWPE produced with the pre-activated complex proved suitable for solvent-free processing into high-strength oriented films.