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The article presents a comparative assessment of various processes of demetallization of heavy petroleum feedstock (HPF). By the example of TAIF-NK JSC, which operates a slurry hydrocracking unit based on VCC process, the possibility of mastering secondary processes aimed at deepening oil refining is shown.

Experimental discovery of ultralarge elastic deformation in nanoscale diamond and machine learning of its electronic and phonon structures have created opportunities to address new scientific questions. Can diamond, with an ultrawide bandgap of 5.6 eV, be completely metallized, solely under mechanical strain without phonon instability, so that its electronic bandgap fully vanishes? Through first-principles calculations, finite-element simulations validated by experiments, and neural network learning, we show here that metallization/demetallization as well as indirect-to-direct bandgap transitions can be achieved reversibly in diamond below threshold strain levels for phonon instability. We identify the pathway to metallization within six-dimensional strain space for different sample geometries. We also explore phonon-instability conditions that promote phase transition to graphite. These findings offer opportunities for tailoring properties of diamond via strain engineering for electronic, photonic, and quantum applications.

Refiners downstream worldwide are devoting more attention to managing industrial impacts and environmental contamination as an approach of reducing the trace metal content of heavy crude oil and its refined products. The removal of Cr 2+ , Ni 2+ , V 4+ , and Zn 2+ (the most significant metal ions) from Egyptian heavy crude oil at the Belayim Desert (BD) oil field has been studied in this work applying the adsorption demetallization technique. Two types of zeolitic materials have been used in the metal removal experiments. Different operating parameters such as contact time, adsorbent concentration and initial metal ions concentration (crude oil quantity) were investigated for their effects on metal removal efficiency. The experimental results of adsorption test showed that the optimal removal conditions using NZ occurred after 6 h contact time, when using 0.5 g of NZ stirred with 50 ml crude oil, these experimental conditions produced maximum V, Ni, and Cr removal efficiencies as 75.6, 73.9, and 81.8% respectively, that cleared at PXRD and EDX analysis to confirm the highly tendency of NZ to remove metal ions from BD crude oil. While the optimal removal conditions using SZ occurred after 12 h contact time, when using 2 g of SZ stirred with 50 ml crude oil, these experimental conditions produced maximum Zn and Cr removal efficiencies as 70.5, 69.17% respectively, but the maximum removal efficiency of V and Ni obtained after 26 h contact time, 2 g SZ with 50 ml crude oil reached to 68.9%. In addition to the results revealed that Natural Zeolite (NZ) is more efficient than Synthetic Zeolite (SZ) in extracting metal ions mainly Ni and V ions from BD crude oil. Also, the selectivity of NZ for heavy metals removal efficiencies are Cr > V > Ni > Zn. Whilst the selectivity of SZ for heavy metals removal efficiencies are Cr > Zn > V > Ni.

The well-known probiotic GRAS Saccharomyces boulardii (CNCM I-745) was used for the first time to produce glutathione (GSH). The culture conditions affecting GSH biosynthesis were screened using a Plackett–Burman design (PBD). Analyzing the regression coefficients for 12 tested variables, yeast extract, glucose, peptone, cysteine, temperature and agitation rate had a positive significant effect on GSH production with a maximum yeild 192 mg/L. The impact of kinetics of adding cysteine was investigated in 19 experiments during the growth time course (0–36 h), and the maximum yield of glutathione (235 mg/L) was obtained by addition of cysteine after 8 h post-inoculation. The most significant variables were further explored at five levels using central composite rotatable design (CCRD), giving a maximum production of GSH (552 mg/L). Using baffled flasks, the yield of GSH was increased to 730 mg/L, i.e., 1.32-fold increment. The two rate-limiting genes of GSH biosynthesis “γ-glutamyl cysteine synthetase (GSH1) and GSH-synthetase (GSH2)” were amplified and sequenced to validate the GSH biosynthetic potency of S. boulardii. The sequences of genes showed 99% similarity with GSH1 and GSH2 genes of S. cerevisiae. Glutathione peroxidase was purified and characterized from S. boulardii with molecular mass and subunit structure of 80 kDa and 35 kDa as revealed from native and SDS-PAGE, ensuring its homodimeric identity. The activity of GPx was reduced by 2.5-fold upon demetallization confirming its metalloproteinic identity. The GPx was strongly inhibited by hydroxylamine and DTNB, ensuring the implication of surface lysine and cysteine residues on the enzyme active site domains.

This study investigated the segregation of metal complexes compounds from Iraqi heavy crude oil in the existence of choline chloride-based deep eutectic solvents (DESs). Using polyethylene glycol (PEG), choline chloride-based (ChCl) deep eutectic solvents were created, and their properties were assessed using Fourier-transform infrared (FT-IR) analyses plus density and viscosity measurements. A method combining ultrasonic assisted oxidative demetallization and deep eutectic solvents is proposed for the separation and removal of these metals from heavy crude oil. The removal of the most abundant elements in crude oil samples was investigated, namely, iron (Fe), zinc (Zn), sodium (Na), nickel (Ni), and vanadium (V). This method was used to evaluate the ability of ionic liquids (ILs) to eliminate metals from heavy crude oil. It was shown that different elements exhibited various elimination rates attributed to their electrochemical properties. Ionic liquids demonstrated complete removal capabilities towards three metals (i.e., Fe, Zn, and Na), while the removal rates reached 42% for V and 39% for Ni, indicating that ILs have significant potential for removing metal complexes from heavy oil. Therefore, deep eutectic solvents showed potential as solvents for liquid–liquid extraction to remove metals ions from heavy crude oil.

The past decade has witnessed a rapid surge of interest in the research and development of non-precious metal-based electrocatalysts for the oxygen reduction reaction （ORR）. Until now, the best catalysts in acidic electrolytes have exclusively been Fe-N-C-type materials from high-temperature pyrolysis. Despite the ORR activities of metal phthalocyanine or porphyrin macrocydes having long been known, their durability remains poor. In this work, we use these macrocycles as a basis to develop a novel organic-carbon hybrid material from in-situ polymerization of iron phthalocyanine on conductive multiwalled carbon nanotube scaffolds using a low-temperature microwave heating method. At an optimal polymer- to-carbon ratio, the hybrid electrocatalyst exhibits excellent ORR activity with a positive half-wave potential （0.80 V）, large mass activity （up to 18.0 A/g at 0.80 V）, and a low peroxide yield （〈3%）. In addition, strong electronic coupling between the polymer and carbon nanotubes is believed to suppress demetallization of the macrocycles, significantly improving cycling stability in acids. Our study represents a rare example of non-precious metal-based electrocatalysts prepared without high-temperature pyrolysis, while having ORR activity in acidic media with potential for practical applications.

The laws of thermal degradation of the mixture of the heavy fraction of low-temperature coal tar and coal shale were investigated using dynamic thermogravimetry. The kinetic characteristics of the process were determined using various methods, including the Ozawa–Flynn-Wall, Friedman, non-parametric kinetics and Šesták–Berggren methods. It is shown that coal shale initiated changes in the kinetic parameters and decomposition rate of the heavy fraction of coal tar. It was found that a 13% content of coal shale in the mixture led to the maximum rate of weight loss of the heavy fraction of coal tar. A hydrodemetallization kinetic model of the mixture of the heavy fraction of low-temperature coal tar and coal shale is proposed. The kinetic parameters of the hydrodemetallization process were determined; in addition, the rate constants at various temperatures were estimated. The study shows that the distribution of trace elements in the hydrogenate from the initial mixture and in the hydrogenate from the solid residue was characterized by relatively low values of reaction rate constants. The maximum microelement distribution rate was achieved in the hydrogenate solid residue. Energy indicators of activation processes indicated that hydrodemetallization at low temperatures is advantageous from an energy point of view.

The pore structure of a hydrotreating catalyst plays a pivotal role in hydrodemetallization (HDM) reactions. To effectively construct a meso-macroporous catalyst, we employed a CTAB-guided in situ TEOS hydrolysis approach to prepare silica-coated γ-Al2O3@SiO2 composite supports. The silica shell incorporation significantly enhances specific surface area and reduces the metal–support interactions, thereby improving the dispersion of NiMo active components and boosting the deposition of metal impurity. Hence, the NiMo/Al2O3@SiO2 catalyst (2.8 wt.% NiO, 4.3 wt.% MoO3) exhibits much higher HDM activity than that of NiMo/Al2O3. This is evidenced by markedly higher demetallization rate constant (1.38 h−1) and turnover frequency (0.56 h−1) of the NiMo/Al2O3@SiO2. The NiMo/Al2O3@SiO2 catalyst further demonstrates excellent recyclability during sequential HDM reactions. This superior catalytic behavior stems from the hierarchical meso-macroporous structure, which simultaneously facilitates the deposition of metal impurities and mitigates deactivation by pore blockage.

Demetallization pretreatment is of great significance for the re-refining of used lubricating oil (ULO) by catalytic hydrogenation. Calcium-containing detergents colloidal stability, pyrolysis properties and kinetics studies have great significance for the demetallization pretreatment, re-refining, and resource utilization of ULO. The present study is focused on the pyrolysis mechanism and determining an accurate pyrolysis kinetic model for the removal of calcium from ULO using vulcanized calcium alkylphenolate (T-115B) colloidal as a model compound. Colloidal stability, pyrolysis process and thermal decomposition products have been studied by DLS, TEM, FTIR spectroscopy and XPS. The reaction energy for primary and secondary dissociation is calculated using the B3LYP-D3(BJ)/6-31g* method. The pyrolysis characteristics at different heating rates have been investigated by TG/DTA, and based on iso-conversional and master plot methods, E and kinetic equation have been determined, which revealed that the process can be divided into two distinct phases and the pyrolysis mechanism and function are necessarily described by a two-step model. The colloid was relatively stable when the temperature is lower than 395 K. When the temperature rises, compounds occur thermal decomposition, alkyl-CH 2 –S bond may be the trigger bond in the initiation process, and CaCO 3 is the main degradation product. Based on iso-conversional methods (KAS and FWO) and master plot methods, values of E are determined as 96.67 and 100.78 kJ mol −1 , respectively. And the pyrolysis reaction in stage 1 indicated that the most probable kinetic model followed an F n mechanism with n  = 1.39, and the second stage was also controlled by an F n mechanism, but with n  = 0.86.

Cellulose was chemically derivatized via the 6-deoxy-6-chloro cellulose (CCl) and 6-deoxy-6-(ethylene-1,2-diamine) cellulose (CCl-En) intermediates synthesis followed by azomethine coupling with salicylaldehyde to obtain 6-deoxy-6-(ethylene-1,2-diamine) cellulose salicylaldehyde azomethine base (CCl-En-Sal). These modified cellulose derivatives were characterized by FT-IR, 13C CP/MAS NMR, TG and SEM–EDX techniques. The cellulose azomethine salicylaldehyde (CCl-En-Sal) were exploited for demetallization of Ni and V from the metal porphyrins present in crude oil. For this, diluted mangla crude oil was mixed with water doped CCl-En-Sal with varying amounts ranging from 100 to 1000 ppm. The emulsion was made by using the 0.1% (m/v) SDBS (sodium dodecylbenzenesulfonate) emulsifier. The de-emulsification was carried out and Ni and V content analysis in the separated oil layer revealed that CCl-En-Sal is effective as demetallization agent for both Ni and V from crude oil. At 1000 ppm concentration the % removal of Ni and V reaches to a maximum of 43.24% and 50.67%, respectively.