Table of Content

12 June 2026, Volume 57 Issue 6

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STUDY ON THE MECHANISM OF CO₂ DESORPTION CATALYZED BY Fe-CONTAINING ZSM-5 ZEOLITE

2026, 57(6):  1-8. 

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To address the issues of high regeneration energy consumption and solvent degradation loss at elevated temperatures for conventional alkanolamine-based carbon capture processes, this study investigated the catalytic regeneration reaction pathways for CO₂ desorption via carbamate decomposition through theoretical calculations. The catalytic performance and structure-activity relationships of various metal-substituted ZSM-5 zeolites for CO₂ desorption were explored, leading to the development of metal-modified ZSM-5 catalysts that facilitate C—N bond cleavage in carbamate molecules and reduce the activation energy of CO₂ desorption. Among the 16 investigated metals, Fe substituted ZSM-5 zeolite exhibited superior electron acceptance capability and significantly reduced the activation energy required for C—N bond activation. The Fe substituted ZSM-5 catalyst displayed optimal catalytic performance and stability for CO₂ desorption, effectively reducing desorption energy consumption and showing substantial potential for application in low-energy CO₂ capture technologies. Fe atoms in ZSM-5 utilize their d-orbitals to accept electrons from carbamate species, inducing electron density transfer from the C atom into the antibonding orbitals of N, resulting in C—N bond elongation and facilitating C—N bond cleavage.

STUDY ON THE MECHANISM OF MOLECULES INTERACTION BETWEEN THICKENER AND BASE OIL IN LUBRICATING GREASE SYSTEM

2026, 57(6):  9-18. 

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Quantum mechanical methods were employed to calculate the intermolecular interaction energies between lithium stearate (Li-ST) thickener and three synthetic base oils, namely polyalphaolefin (PAO3.6), alkyl naphthalene (AN3), and diisooctyl sebacate (DOS). The results showed that the interaction between PAO3.6 and Li-ST molecules was dominated by dispersion forces. For AN3 and DOS, a synergistic coupling of hybrid orbital interactions and dispersion forces was formed with the Li-ST thickener via π-electron delocalization and ester group coordination, respectively. The interaction energies between the three synthetic base oils and Li-ST increase in the order of PAO3.6 < AN3 < DOS. Frontier molecular orbital analysis confirmed that electron transfer occurs for the thickener in polar systems, accompanied by a gradual reduction in the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The performance characterization results of the as-prepared synthetic lubricating greases revealed that higher intermolecular interaction energy corresponds to superior colloidal stability and tribological performance of the greases. Accordingly, the overall performance of the three synthetic lubricating greases ranked from low to high as follows: PAO3.6-based lubricating grease < AN3-based lubricating grease < DOS-based lubricating grease.

MOLECULAR SIMULATION STUDY ON ADSORPTION BEHAVIOR OF n-HEPTANE ON MFI TYPE ZEOLITE

2026, 57(6):  19-25. 

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Using the configurational bias Monte Carlo (CBMC) simulation method, the adsorption behavior of n-heptane on MFI type zeolites (ZSM-5) was systematically studied. Over a wide temperature range (303—623 K) and pressure range (0.5—10 kPa), adsorption isotherms, isobars, adsorption heat, and adsorption site distributions were examined. The results indicate that n-heptane adsorption on MFI type zeolites follows the dual Langmuir adsorption isotherm model. At low pressures, the interactions between molecules and the framework are strong, and the adsorption amount rises rapidly. With increasing temperature, the adsorption amount decreases significantly, and the distribution of adsorption sites undergoes a configurational change. Heat of adsorption analysis shows that at low temperatures adsorption is influenced by intermolecular cooperative effects, whereas at high temperatures it is mainly controlled by the framework potential field. Especially under high temperature conditions of 623 K, n-heptane molecules exhibit pronounced shape-selective adsorption characteristics, preferentially occupying straight channels with smaller spatial hindrance and deeper potential wells, while the adsorption density in sinusoidal channels is very low. This study systematically elucidates the mechanism by which temperature and pressure affect the adsorption capacity and spatial distribution of n-heptane on MFI type zeolites, deepening the understanding of alkane adsorption behavior within zeolite channels and providing a theoretical basis for the optimized design of related adsorption separation and catalytic processes.

DEVELOPMENT AND APPLICATION OF A COMBINED PROCESS FOR DEEP RECOVERY OF LIGHT HYDROCARBONS FROM SATURATED REFINERY DRY GAS

2026, 57(6):  26-35. 

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Aiming at the problems existing in the recovery process of light hydrocarbons (C₂+ components) from saturated refinery dry gas, such as high residual C₂+ content in dry gas, low recovery rate of ethane and light hydrocarbons, and relatively high energy consumption, an efficient combined absorption (ECA) process for deep recovery of light hydrocarbons was developed. The process adopts the technical route of “three-stage absorption and multi-stage separation”. Through the optimal combination of propane, butane and toluene as well as sequential graded absorption, efficient capture of C₂+ components in saturated dry gas is realized. Process simulation results show that the ECA process can increase the recovery rate of ethane and light hydrocarbons to more than 98%, the mole fraction of C₂+ components in the treated dry gas is no more than 1.0%, and the unit comprehensive energy consumption is reduced by more than 17% compared with the traditional scheme. After the newly built industrial unit was put into operation, the recovery rates of ethane and C₂+ light hydrocarbons reached 98.85% and 98.23% respectively, and the mole fraction of C₂+ components in dry gas was no more than 1.0%, realizing the deep recovery and high-value utilization of C₂+ light hydrocarbons. The process has technical advantages of low absorbent circulation rate, high product purity and low energy consumption, with remarkable economic benefits and broad prospects for industrial popularization and application.

IMPACT OF FEEDSTOCK PROPERTIES ON THE REACTION PERFORMANCE OF RESIDUE HYDROTREATING

2026, 57(6):  36-43. 

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To elucidate the influence of feedstock properties on the reaction performance in fixed-bed residue hydrotreating, five blended feedstocks comprising vacuum residues from different sources and catalytic cracking diesel were selected for fixed-bed hydrotreating experiments under identical catalyst grading and process conditions. Based on the feedstocks’ macroscopic properties combined with the aromatic carbon ratio, correlation analysis and model construction were conducted with the hydrotreating reaction rate constants. The results indicate that the macroscopic properties of the feedstock can effectively correlate with the difficulty of asphaltene hydroconversion, vanadium removal, and carbon residue reduction, but show lower correlation with other reactions. After introducing the aromatic carbon ratio, the correlation of the macro-micro hybrid model with the hydrodesulfurization reaction rate constant improved significantly; however, it did not enhance correlations with other hydroprocessing reactions. The sulfur-to-carbon-residue ratio is identified as the core factor affecting residue hydroprocessing performance. A higher sulfur content coupled with a lower carbon residue corresponds to better reaction performance of the residue feedstock.

FIRST COMMERCIAL APPLICATION OF VACUUM GAS OIL TWO-PHASE LOW-TEMPERATURE DE-PHOSPHORIZATION AND DE-IRONIZATION TECHNOLOGY

2026, 57(6):  44-48. 

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To address the issue of increasing pressure drop in downstream vacuum gas oil (VGO) hydrogenation units, CNOOC Ningbo Daxie Petrochemical Co., Ltd. commissioned a 0.70 Mt/a VGO de-phosphorization and de-ironization unit in August 2024. This unit utilizes the two-phase low-temperature de-phosphorization and de-ironization technology for VGO, along with its proprietary adsorbent, both developed by SINOPEC Research Institute of Petroleum Processing Co., Ltd., marking the first industrial application of this technology. The industrial calibration results indicate that at an adsorption temperature of approximately 237 °C, the average removal rates of phosphorus and iron reached 90.0% and 78.7%, respectively. This effectively achieved the targeted removal of these contaminants, exceeding the guaranteed design values. Two months of stable industrial operation indicate consistent adsorbent efficiency, confirming its suitability for long-term operation. Compared to the previous operation cycle, the rate of pressure drop increase in the downstream 2.10 Mt/a VGO hydrogenation unit has been significantly reduced, thereby substantiating the role of the de-phosphorization and de-ironization unit in alleviating pressure drop rise in downstream facilities.

IMPROVEMENT MEASURES OF SLURRY FRACTIONATION SYSTEM IN SLURRY BED HYDROTREATING UNIT

2026, 57(6):  49-55. 

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To maximize the utilization of crude oil resources, the efficient processing of residue oil is of paramount importance. Slurry bed residue oil hydrogenation technology, due to its high conversion rate, is regarded as a critical pathway for the upgrading of inferior heavy residue oil. Based on the operational performance of three 3.0 Mt/a slurry bed residue oil hydrogenation units (A, B, and C), an analysis of the process design characteristics of the slurry fractionation system was conducted. From perspectives such as the design of the slurry fractionation system, control of the primary reaction conversion rate, optimization of operational parameters, and selection of internal equipment components, optimization strategies for the long-term stable operation of the slurry fractionation system were proposed. After implementing these optimization strategies, the slurry fractionation system has experienced no spiral plate leakage over extended periods, and the separation efficiency of products has improved. Consequently, the slurry bed residue oil hydrogenation unit can achieve long-term stable operation.

PROCESS DESIGN AND FEASIBILITY ANALYSIS OF SELECTIVE CATALYTIC OXIDATIVE DESULFURIZATION FOR WELLHEAD GAS

2026, 57(6):  56-64. 

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Conventional desulfurization technologies employed for small- and medium-scale sour wellhead gas suffer from several drawbacks, including complex process flow, high energy consumption, large reagent dosage, and difficult disposal of sulfur paste. Aimed at wellhead gas with H₂S volume fraction below 1.5% and based on the irreversible and exothermic characteristic of the selective catalytic oxidation of H₂S, an automated fixed-bed selective catalytic oxidative desulfurization process (SCO-DO) was proposed and designed, and its feasibility for wellhead gas desulfurization was systematically analyzed. The SCO-DO process integrates dual-reactor switching and regeneration, waste heat recovery, and supplementary refining, thereby addressing the bottlenecks of catalyst deactivation caused by sulfur deposition, excessive energy consumption, and difficulty in meeting purification standards. In comparison with the traditional high-pressure chelated iron process and amine absorption coupled with self-circulating chelated iron process, the SCO-DO process features simpler flow path and lower operating cost. The desulfurization product is commercial-grade elemental sulfur, leading to outstanding environmental benefits and great potential for industrial application.

TRANSFORMATION AND EFFECT OF No.60 INDUSTRIAL HEXANE SOLVENT OIL PROJECT

2026, 57(6):  65-71. 

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The aromatics extraction unit of a petrochemical company was put into operation in 1995, and the original design did not take into account the production of hexane solvent oil.After a transformation in May 2001, it became capable of producing hexane solvent oil that could meet the internal supply standards of the enterprise. To further improve the quality of hexane solvent oil, a transformation plan for the No.60 industrial hexane solvent oil project was proposed. Through the selection of several transformation plans, it was decided to move the No.6 solvent extraction line of the solvent oil separation tower downward to the original No.120 solvent extraction line position and add a packing section between the hexane component and the No.6 solvent oil extraction to enhance their separation effect. At the same time, by simply adjusting the process and reusing the existing pump, the transformation cost was reduced. After implementation in August 2024, No.60 industrial hexane solvent oil that can meet the GB/T 17602—2018 standard was produced, and the output of No.60 industrial hexane solvent oil was also increased.

ANALYSIS OF LEAKAGE CAUSES AND COUNTERMEASURES OF DRYING TOWER IN ACID REGENERATION UNIT OF ALKYLATION PLANT

2026, 57(6):  72-78. 

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Continuous corrosion leakage occurred on the wall of the drying tower in the concentrated acid area of the acid regeneration unit of an alkylation plant in a petrochemical company. To investigate its failure mechanism, systematic tests were carried out on the failed samples by means of macroscopic observation, chemical composition analysis, metallographic examination, scanning electron microscopy and energy spectrum analysis. Combined with actual process operation parameters, it is determined that excessively high operating temperature and replacement of the tower wall material are the root causes of the failure.Based on the analysis results, targeted improvement measures were formulated from two aspects: optimizing process operation and improving the corrosion resistance of materials, so as to effectively ensure the long-term safe and stable operation of the equipment.

STEAM-ASSISTED SYNTHESIS OF CORE-SHELL ALUMINA WITH FIVE-COORDINATE Al3+ FOR PREPARING HIGHLY ACTIVE PALLADIUM CATALYSTS

2026, 57(6):  79-87. 

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Through steam-assisted method, we achieved in situ reconstruction of commercial alumina to synthesize a core-shell alumina support with abundant penta-coordinated Al³⁺. By optimizing the reconstruction conditions, the irregular nanoparticles on the commercial alumina surface were transformed into the micron-thick layer of columnar alumina, increasing the specific surface area from 148 m²/g to 377 m²/g. The proportion of unsaturated penta-coordinated aluminum species reached 16.25%. Using the alumina as the catalyst support, Pd-based noble metal catalysts were fabricated; the unsaturated penta-coordinate Al³⁺ active sites on the support exhibited a strong anchoring effect on the noble metal species, effectively inhibiting their agglomeration. Compared with commercial alumina, the Pd species supported on the optimally restructured alumina exhibited improved dispersion and a reduced particle size, which decreased from 2.5 nm to 1.0 nm. The as-prepared noble metal catalyst was employed for the anthraquinone hydrogenation reaction, and its hydrogen efficiency was improved by 12% compared with the commercial noble metal catalyst. These results demonstrate the feasibility of synthesizing the core-shell alumina support with five-coordinate Al³⁺ via the steam-assisted method, and provide guidance for the development of industrial noble metal catalysts.

STUDY ON PREPARATION AND CATALYTIC PERFORMANCE OF NiMoZn/γ-Al₂O₃ CATALYST FOR METHANE-ASSISTED RESIDUE UPGRADING

2026, 57(6):  88-98. 

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Metal catalysts loaded with Ni, Mo, and different metal promoters M (M = Zn, Co, Ce, Ag) were prepared using mesoporous γ-Al₂O₃ as a support via the impregnation method. The catalyst was characterized using scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption, pyridine infrared, and NH? programmed temperature desorption. The effects of different mixed reaction atmospheres (methane-nitrogen, nitrogen-hydrogen, methane-hydrogen) and various metal promoters M (M = Zn, Co, Ce, Ag) on catalytic performance. The effects of reaction temperature (390–420 ℃) and varying promoters metal loading on the reforming of residue oil were also systematically investigated. Results indicate that in methane-hydrogen mixed atmosphere, the introduction of a small amount of hydrogen aids methane activation and enhances the reforming effect of residue oil over methane. In the NiMo/γ-Al₂O₃ catalyst, Ni and Mo species are highly dispersed, exhibiting an increase in B acid sites and a decrease in L acid sites. The optimal loading amounts for Ni and Mo are 10% and 20%, respectively. The introduction of metal additives M improved residue oil quality, with Zn exhibiting the best reaction performance. Metal Zn increased L-acid sites in the catalyst and synergized with active metals Ni and Mo to enhance methane activation capacity. Moderately elevated reaction temperatures (390–420 ℃) enhance oil upgrading. Under 420 ℃ conditions, optimal upgrading yields were achieved: upgraded oil viscosity decreased by 98.55%, asphaltene content dropped by 88.41%, desulfurization rate reached 38.65%, and denitrification rate reached 37.14%.

STUDY ON DEACTIVATION OF AN INDUSTRIAL VANADIUM PHOSPHORUS OXIDE CATALYST

2026, 57(6):  99-103. 

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The performance variation of industrial vanadium phosphorus oxide (VPO) catalyst for n-butane oxidation to maleic anhydride under phosphorus replenishment conditions was investigated. By comparing the fresh catalyst with the catalyst after four years of industrial operation, various physicochemical characterization techniques were employed to analyze the crystal phase structure, surface acidity, elemental composition, and valence state of the catalyst. The results indicated that the specific surface area, pore volume, and pore size of the catalyst after long-term operation changed insignificantly, but the crystal phase structure underwent significant changes. The vanadium(V) phosphate (VOPO₄) phase gradually disappeared, and the catalyst mainly existed in the form of the vanadium(Ⅳ) pyrophosphate ((VO)₂P₂O₇) phase. Meanwhile, severe phosphorus loss occurred on the catalyst surface, leading to a decrease in acidity, a reduction in the average vanadium valence, and a decrease in surface oxygen concentration. In the reactor, as the operation time extended, the average reaction temperature gradually increased, and the molar yield of maleic anhydride gradually decreased.

APPLICATION OF SULFIDED CATALYSTS FOR TAIL GAS HYDROGENATION IN SULFUR RECOVERY UNITS

2026, 57(6):  104-109. 

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In response to the issues of prolonged start-up time during the pre-sulfidation process of the original oxidized-state tail gas hydrogenation catalyst and high SO₂ emissions in the flue gas, a sulfided-state tail gas hydrogenation catalyst was adopted in the hydrogenation reactor of a 40 kt/a sulfur recovery unit at a certain company. This article summarizes the operational procedures and precautions for the sulfided-state tail gas hydrogenation catalyst during start-up, and analyzes its practical application performance and advantages. The results show that the sulfided-state tail gas hydrogenation catalyst can be safely put into operation, the start-up time significantly reduced, saving fuel gas, hydrogen, and electricity consumption, and lowering operational costs by 67 000 yuan. During the start-up period, SO2 emissions were reduced by 98%. The performance of the sulfided-state tail gas hydrogenation catalyst meets the requirements for long-term stable operation of the sulfur recovery unit, demonstrating significant environmental benefits.

PREPARATION OF HIERARCHICAL POROUS Pt/SSZ-32 AND THEIR CATALYTIC PERFORMANCE IN HYDROISOMERIZATION OF n-ALKANES

2026, 57(6):  110-118. 

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To address the issues of narrow micropores, high diffusion resistance, and low utilization of active sites in traditional n-alkane hydroisomerization catalysts, a series of hierarchical porous Pt/SSZ-32 catalysts were prepared by inorganic/organic mixed base modification. The effects of different modification times on the phase structure, pore structure, acidity and acid content of the hierarchical porous catalyst, as well as the catalytic performance in the hydroisomerization of n-hexadecane were investigated. The results showed that the addition of an organic base avoided excessive desilication and dealumination of the molecular sieve framework by the inorganic strong base, resulting in smaller and more uniform mesopores, reducing loss of acid sites, and improving the accessibility of active sites within the molecular sieve and the mass transfer capacity of the reaction products. With the increase of mixed base modification time, the pore volume and specific surface area of the modified mesopores continuously increase, while the proportion of framework Al decreases and the proportion of non-framework Al increases. This leads to a decrease in both the acidity and acid strength of the catalyst, resulting in a decline in catalyst activity. The optimal mixed base modification time for the molecular sieve is 10 min. Under this modification condition, the catalyst prepared exhibits the highest selectivity for hydroisomerization and the lowest selectivity for cracking reactions, achieving a 73.6% yield of isohexadecaneat 270 ℃. Therefore, the hydroisomerization activity and selectivity of the catalyst can be effectively controlled by adjusting the mixed base modification time.

PREPARATION AND PERFORMANCE OF NOVEL Fe₂O₃/g-C₃N₄ HETEROJUNCTION PHOTO-FENTON REAGENTS

2026, 57(6):  119-130. 

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In this study, a Fe₂O₃/g-C₃N₄ heterojunction photocatalyst was synthesized via a straightforward thermal polymerization approach. The material's structural features were thoroughly characterized using techniques such as XRD, XPS, and TEM. Furthermore, photoelectrochemical measurements were employed to systematically investigate the separation and migration behavior of photogenerated charge carriers. Tetracycline, a representative antibiotic contaminant, was selected as the target pollutant to evaluate the catalytic degradation efficiency and elucidate the underlying mechanism. Experimental results demonstrated that the as-prepared heterojunction catalyst achieved a tetracycline degradation efficiency of 99.5% within 90 minutes, with a reaction rate constant 30.3 times higher than that of pristine g-C₃N₄. After loading g-C₃N₄ on Fe₂O₃, the band gap width is effectively reduced, extending the light response range to the visible light region. The formed type-II heterojunction significantly promotes the separation and transfer efficiency of photogenerated carriers. Mechanistic analysis revealed that under PMS activation, the Fe₂O₃/g-C₃N₄ system generates various reactive species,including h⁺, .O^2-, ¹O₂， and .OH,that collectively contribute to pollutant decomposition. Additionally, the efficient Fe²⁺/Fe³⁺ redox cycle ensures excellent recyclability, maintaining high activity over five consecutive cycles.

APPLICATION RESEARCH OF CRUDE OIL SCHEDULING OPTIMIZATION BASED ON THE Dueling DQN ALGORITHM

2026, 57(6):  131-139. 

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Focusing on the application of deep reinforcement learning in crude oil scheduling, the scheduling process is modeled as a Markov decision process, and the Dueling DQN algorithm is adopted to solve the crude oil scheduling optimization problem. To address challenges such as disparate state scales and fluctuating reward distributions, state normalization and reward standardization mechanisms are designed to enhance training stability and convergence efficiency. Furthermore, the complexity of the action space is effectively reduced through the strategic simplification of unloading decision dimensions. Experimental results demonstrate that the proposed method can generate stable, feasible, and cost-effective scheduling plans while satisfying various process and operational constraints. These outcomes verify the effectiveness and application potential of deep reinforcement learning in optimizing complex crude oil scheduling tasks in refinery operations.

COMPARISON OF TOLUENE DISPROPORTIONATION PROCESS ROUTES AND OPTIMIZATION OF SEPARATION PROCESSES

2026, 57(6):  140-146. 

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Against the dual backdrop of the transformation from oil refining to chemical engineering and the sustained growth in demand for high-purity benzene, the disproportionation process technology for producing more benzene from toluene has attracted attention. To explore the differences between the pure toluene disproportionation process and the toluene shape-selective disproportionation process, process simulation and optimization were carried out, and their impacts on downstream units were analyzed. The results show that the energy consumption of the pure toluene disproportionation process is 41% lower than that of the toluene shape-selective disproportionation process, and the energy consumption of the product separation unit accounts for as high as 85% of the total energy consumption. A heat-integration scheme with a dividing wall column was adopted to optimize the BTX product separation process, reducing the total heat load and total cooling load by 30.8% and 32.8%, respectively. When applied to the entire toluene disproportionation process, this optimization scheme reduced utility consumption, and the operating cost could be decreased by 10%—15%. Finally, based on the same toluene feed processing capacity, the impacts of mixed xylene products with different paraxylene (PX) concentrations produced by the two disproportionation technology routes on the downstream PX separation unit were compared. The results indicate that the energy consumption of the combined process with toluene shape-selective disproportionation is approximately 9% lower than that of the combined process with pure toluene disproportionation.

IMPROVING DUAL-PREVENTION INSPECTION QUALITY BY INTEGRATING VIDEO SURVEILLANCE PLATFORM AND PERSONNEL POSITIONING SYSTEM

2026, 57(6):  147-152. 

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This paper proposes an intelligent inspection solution integrating video surveillance and personnel positioning systems to address issues such as blind spots and data fragmentation in traditional dual-prevention inspections. Through precise location management, multimodal anomaly detection, and dynamic visual management, closed-loop inspection control is achieved. The system innovatively combines positioning data with video analytics to automatically verify inspection completion rates, identify trajectory anomalies, and optimize resource allocation via heatmaps.

MOLECULAR STRUCTURE CHARACTERIZATION OF POLYETHYLENE PYROLYSIS OIL BY COMPREHENSIVE TWO-DIMENSIONAL GAS CHROMATOGRAPHY–TIME-OF-FLIGHT MASS SPECTROMETRY

2026, 57(6):  153-159. 

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The detailed molecular composition of pyrolysis oil derived from waste polyethylene (PE) plastic was systematically characterized using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOF MS). The results show that the main components of the PE pyrolysis oil are n-alkanes (mass fraction 27.88%), α-olefins (mass fraction 31.54%), and linear dienes (mass fraction 5.07%). Concurrently, hydrocarbon compounds such as cyclic olefins, alkenylbenzenes, and polycyclic aromatic hydrocarbons were detected. Furthermore, non-hydrocarbon components including oxygenated compounds (e.g., benzoic acid), nitrogenous compounds (e.g., caprolactam), and trace chlorinated compounds were identified. These substances primarily originate from plastic additives or feedstock contamination. A comparative analysis of two PE pyrolysis oils from different sources revealed significant differences in their molecular composition, indicating that the pyrolysis process, catalysts, and feedstock type have a substantial impact on the product distribution. Consequently, this technique can provide crucial data support for the precise molecular characterization, product control, and subsequent processing and utilization of waste plastic pyrolysis oils.

STUDY ON SYNTHESIS AND PERFORMANCE OF BIOLOGICAL SLIME DISPERANT

2026, 57(6):  160-166. 

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A series of organic guanidine-based biological slime disperants have been synthesized, with oil-based guanidinium acetate GA5 presenting the best performance. It demonstrated favorable dispersion capacity on biological slime and excellent bactericidal activity against heterotrophic bacteria, sulfate-reducing bacteria and iron bacteria. When its mass concentration exceeded 10 mg/L, the dispersion efficiency on biological slime was evaluated over 70% through the photoelectric effect method, significantly outperforming existing chemicals. The dispersion efficiency was almost unaffected with the total alkalinity at 0-600 mg/L and calcium hardness at 0-1000 mg/L. It was found that this guanidine derivative has minimal interaction with corrosion and scale inhibitors, demonstrating their good compatibility. This compound could effectively reduce the surface tension, infiltrate and penetrate into the biological slime, and disperse it into tiny particles.

PERFORMANCE AND COMPOSITION CHANGES OF MINERAL INSULATING OILS UNDER ELECTRIC FIELD IONIZATION

2026, 57(6):  167-176. 

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In order to investigate the performance and compositional changes of transformer oil under long-term, low-intensity partial discharge conditions, ionization tests were conducted on mineral insulating oil under high-voltage AC fields in hydrogen/nitrogen atmospheres. The insulation properties, physicochemical characteristics, and hydrocarbon composition of the oil samples were systematically analyzed after different durations of ionization. The results show that, with increasing ionization time, the hydrocarbon group composition of aromatic-free insulating oil remains essentially stable and is less affected by the ambient atmosphere. In contrast, in aromatic-containing insulating oil, the content of monocyclic aromatics increases while that of bicyclic aromatics decreases, and these changes are significantly influenced by nitrogen and hydrogen atmospheres. A high concentration of hydrogen promotes the conversion of bicyclic aromatics to monocyclic aromatics and further to naphthenes, while inhibiting the dehydrogenation of naphthenes to form aromatics. After ionization, all insulating oil samples exhibit increased average relative molecular mass, density, kinematic viscosity, and dielectric loss factor, along with degraded insulation performance. Moreover, the gas absorption capacity of high-aromatic oil decreases after ionization, while the gas evolution property of low-aromatic oil improves. However, throughout the entire test process, the gas evolution behavior of high-aromatic oil remains superior to that of low-aromatic oil.

STUDY ON CORROSION BEHAVIOR OF TYPICAL MATERIALS IN PROCESSING HIGH ORGANIC CHLORIDE-CONTAINING CRUDE OIL

2026, 57(6):  177-184. 

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This study statistically examines 16 domestic and international corrosion failure cases in refineries induced by processing organic chloride-containing crude oil, focusing on affected units, equipment,and root causes. The corrosion behaviors of 20# carbon steel and 2205 duplex stainless steel (DSS) in varying NH₄Cl solutions and wet NH₄Cl salt deposits were investigated via thermodynamic calculations of NH₄Cl environments, mass loss tests, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), as well as characterization by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and 3D optical microscopy. Results indicate that atmospheric-vacuum distillation and hydrogenation units (including reforming pre-hydrogenation systems) are most vulnerable to corrosion during organic chloride crude processing, with heat exchangers and pipelines suffering localized leakage, ammonium salt deposition,and chloride stress corrosion cracking. Water washing mitigates salt deposition but generates a highly corrosive low-pH NH₄Cl environment: the pH of 5 000 mg/L NH₄Cl solution decreases from 5.17 (25°C) to 3.85 (150°C) with rising temperature. 20# carbon steel undergoes uniform corrosion in NH₄Cl solution, with controllable rates at low concentrations (<200 μg/g), but complete corrosion failure under wet salt deposits. 2205 DSS exhibits low general corrosion rates, yet its pitting breakdown potential drops sharply with increasing NH₄Cl concentration; EDS analysis confirms preferential corrosion of the austenite phase. Sulfides inhibit chloride corrosion: They promote protective film formation on carbon steel to reduce corrosion rates, and decrease pitting sensitivity of 2205 DSS.

PROGRESS IN THE SYNTHESES OF TWO-DIMENSIONAL ZEOLITE NANOSHEETS

2026, 57(6):  185-194. 

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Two-dimensional (2D) zeolite nanosheets, which combine an ultra-large external surface area with intracrystalline microporous channels, can effectively alleviate diffusion limitation. Their controllable preparation have attracted widespread attention. Herein, the syntheses of representative MWW, MFI, and FER 2D zeolite nanosheets, along with strategies to construct interlayer architectures using nanosheet layers, are systematically summarized, including post-treatment methods such as swelling-exfoliation/pillarization, the use of special organic structure-directing agents, and direct crystallization assisted by organic/inorganic additives. The characteristics of different methods in terms of structural control and scalable production are also analyzed. Finally, the challenges in the synthesis of 2D zeolite nanosheets are summarized, and future directions for development are prospected.

REVIEW OF PHOTOCATALYTIC BEHAVIOR OF MICROPLASTICS IN PETROCHEMICAL WASTEWATER

2026, 57(6):  195-204. 

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Petrochemical wastewater typically exhibits characteristics such as high pollutant loads and complex oil-water multiphase structures. Under typical operating conditions like crude oil desalting and certain refining process effluents, it also demonstrates elevated salinity levels, thereby posing significant environmental hazards.This review systematically analyzes the dynamic regulation mechanisms of microplastics in photocatalytic degradation of pollutants. By integrating the characteristics of petrochemical wastewater, it elucidates radical conversion under high salinity, mass transfer limitations in oily systems, enhanced π-π interactions between aromatic pollutants and microplastics, and the radical quenching effect of natural organic matter. This provides a mechanistic framework for photocatalytic treatment of complex systems.