Table of Content

12 April 2025, Volume 56 Issue 4

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RESEARCH PROGRESS IN UNDERSTANDING AND ANALYTICAL METHODS OF HYDROGENATION CATALYST STRUCTURE

2025, 56(4):  1-10. 

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The active phase structure of hydrogenation catalysts and its influencing factors in the preparation process were reviewed, and the analysis of the active phase structure by using traditional characterization methods, in-situ characterization techniques and theoretical calculation methods were focused. By summarizing the analytical characterization techniques and theoretical computational results for the active phase structure, the essence of hydrogenation catalysts has been analyzed. In addition, the problems existing in the current structural analysis methods were also pointed out, and the future development of the research direction of hydrogenation catalyst structure was prospected, aiming to offer a theoretical foundation for the development of high-performance hydrogenation catalysts.

ADVANCES OF RESEARCH ON COLLISION-INDUCED DISSOCIATION IN CHARACTERIZING PETROLEUM MOLECULAR STRUCTURE

2025, 56(4):  11-17. 

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Mass spectrometry has been widely used in petroleum chemistry. With the continuous improvement of mass resolution, the use of high/ultra-high resolution mass spectrometry to study the detailed composition of petroleum has become an important direction of petrochemical research. Significant progress has been made in the field of petroleum molecular composition research. Based on the collision-induced dissociation technology, the parent structure and side chain structure of the compounds can be explored on the basis of high-resolution mass spectrometry, so as to realize the fine characterization of the molecular structure of petroleum, and provide a scientific basis for petroleum molecular chemistry and heavy oil hydrogenation process. The research progress of collision-induced dissociation on the characterization of petroleum molecular structure is reviewed, including the principle of collision-induced dissociation, the calculation of dissociation energy and the control of collision energy, as well as the application of collision-induced dissociation characterization of model compounds and real petroleum molecules. Through collision-induced dissociation characterization, the fine structure of petroleum molecules can be deeply understood in order to guide the related processes of heavy oil hydrogenation and provide references for the development and optimization of catalysts.

RESEARCH PROGRESS AND OUTLOOK IN THE GASIFICATION OF PLASTIC WASTES

2025, 56(4):  18-24. 

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In view of the current situation that the recycling of low-value plastic wastes are difficult, and in response to a series of problems caused by their high volatility, low fixed carbon, complex composition and other characteristics, the research progress of existing gasification technologies of plastic wastes are reviewed based on the understanding of existing chemical recycling technologies. The influences of reactor type, gasification medium, temperature, catalysts and other carbonaceous feedstocks on the process of gasification are highlighted. The domestic and foreign industrialization projects of plastic waste gasification are also presented. Finally, the existing problems of plastic waste gasification technology are analyzed, and the future development strategy of gasification technology is described. At last, the development prospects of gasification technology are proposed.

RESEARCH PROGRESS ON GREEN THERMAL UPGRADING TECHNOLOGY OF HEAVY OIL

2025, 56(4):  25-32. 

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Unconventional oil has high viscosity and poor fluidity, which severely restricts its transportation and downstream processing. How to upgradeit has become the key to its development and utilization. Driven by stringent environmental protection requirements and the dual-carbon policy, the upgrading of unconventional oil is bound to move towards a green and clean direction. Based on this, this paper reviews the research progress in the greenthermal upgrading technologies for unconventional oil, with heavy oil as a typical representative. These technologies include traditional hydrogen/hydrogen donor thermal cracking , upgrading with supercritical water , upgrading with hydrogen from water-gas shift reaction, and upgrading under methane. The theoretical research foundations, technical advantages, constraints, industrial application progress, and prospects of various green upgrading technologies are analyzed, providing reference and guidance for the innovation and development of green upgrading technology for heavy oil.

REVIEW OF HYDROGEN SULFIDE REMOVAL TECHNOLOGY FROM NATURAL GAS

2025, 56(4):  33-41. 

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With the proposed goal of "carbon peak" and "carbon neutrality", the Chinese government has increasingly strict requirements for the waste gas treatment of sulfur-containing industries. As a clean and low-carbon fossil energy, natural gas is an important part of the construction of China's new energy system. H₂S, a colorless highly toxic gas, widely exists in natural gas, which will have great damage to the health of equipment and mining personnel during its mining process, so the removal of H₂S in natural gas is very important. The research progress of H₂S removal technology from natural gas is reviewed, the technical characteristics of the method are summarized, and the new desulfurization technology is prospected, which can provide ideas for the development of desulfurization technology.

DEVELOPMENT AND APPLICATION OF ULTRA-DEEP DESULFURIZATION AND DEAROMATIZATION COMPOSITE DIESEL HYDROTREATING TECHNOLOGY BY DUAL REACTOR ZONE

2025, 56(4):  42-49. 

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In order to solve the problem that nitride affects the diesel ultra-deep desulfurization and the high hydrogen consumption caused by oversaturation during PAHs hydrotreating, based on the axial feed properties and reaction environment changes of fixed-bed diesel hydrotreating reactor, the dual-zone ultra-deep desulfurization and dearomatization composite diesel hydrotreating process (RTS-Apro) technology was developed. The results of the pilot test showed that the dearomatization of PAHs can be enhanced and the saturation of monocyclic aromatic hydrocarbons can be reduced when the temperature difference of the dual-zone reaction was 20―40 ℃ at the beginning of the operation and the preferable temperature difference in the middle and late stages was 40 ℃. Increased volume ratio of hydrogen to oil is favorable to the removal of refractory sulfides and the moderate saturation of PAHs. The results of industrial application showed that the average sulfur content of refined diesel products obtained was only 5 μg/g, and the average mass fraction of PAHswas only 1.6%, with low catalyst inactivation rate of only 0.5 ℃/month (calculated as 30 days in a month), which is conducive to the long-term stable operation of the catalyst.

INVESTIGATION ON BEHAVIORS OF THERMAL CONVERSION OF ASPHALTENE IN THE PRESENCE OF HYDROGEN AND CATALYST

2025, 56(4):  50-58. 

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The analysis results of the composition and molecular structure of several typical asphalt molecules show: Several types of asphalt are mainly composed of continental asphalt structure (generally>75%), most asphalt molecules have a high content of heteroatoms, especially sulfur(generally 3%-8%), and there may be multiple heteroatoms in one asphalt molecule. The sulfur in asphaltene is mainly thiophene sulfur(generally>80%), nitrogen is mainly in the form of pentacyclic pyrrole(generally>79%), and the form of oxygen is relatively complex.Experiments using asphaltene and inferior residue with high asphaltene content showed that most of the asphaltene molecules from different sources could be cracked(general cracking rate>77%). The experimental results of inferior residue catalytic hydrothermal conversion showed that asphaltene with five-membered heterocyclic rings was easier to convert, and asphaltene without heterocyclic rings was more difficult. The higher content of five-membered heterocyclic rings (especially five-membered thiophene rings) the asphaltene had, the higher the cracking rates was. Experiments on catalytic hydrothermal conversion of inferior residue with high asphaltene content showed that asphaltene could be cracked efficiently with appropriate reaction temperature(≯435℃), higher hydrogen partial pressure(≮12 MPa), longer reaction time(≮10 h) and higher catalyst concentration(≮1000 μg/g).

STUDY ON LIQUEFACTION CHARACTERISTICS OFRECYCLED WASTE PLASTIC PARTICLE

2025, 56(4):  59-63. 

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By using a specific composition of solvent oil and subjecting the recycled waste plastic particles produced by a domestic waste plastic processing plant to liquefaction treatment under the conditions of a certain temperature and stirring rate, the liquefaction rate of recycled waste plastic particles in the specific solvent oil and the viscosity of waste plastic liquefied liquid were measured, and the correlation formula between the viscosity of waste plastic liquefied liquid and the concentration of recycled waste plastic particles was established. The experimental results demonstrated that the mass fraction of recycled waste plastic particles in the waste plastic liquefied liquid is the main factor affecting the liquefaction rate of recycled waste plastic particles and the viscosity of waste plastic liquefied liquid.

INDUSTRIAL TECHNOLOGY PRACTICE OF REDUCING DIESEL CONTAINING HEAVY AROMATIC HYDROCARBON IN REFINING ENTERPRISES

2025, 56(4):  64-69. 

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In view of the problems such as large output of heavy aromatics diesel, high ratio of fuel to gasoline, low proportion of vehicle diesel and low cetane index, LTAG process combining hydrofining and catalytic cracking was used to convert heavy aromatics diesel into gasoline. RLG technology was used to convert aromatics in diesel distillate into high-octane gasoline components, which further improved the conversion rate of diesel and the quality of gasoline products. RLG diesel oil is smelted in the second riser reactor of RTC unit, and heavy aromatics diesel oil is deeply transformed into light aromatics, and the industry chain of light aromatics is expanded. The results show that the ratio of fuel to gasoline decreases from 1.18 to 0.95 after the transformation of LTAG. After the RLG unit is put into operation, the ratio of fuel to gasoline is further reduced to 0.74. After the RLG diesel is reheated in the second riser reactor of RTC, the fuel to gas ratio is reduced to 0.42. The results of economic benefit calculation show that the application of “RTC+RLG+AromaticsExtraction” combination technologyreduces the production of heavy aromatics diesel oil, increases the production of gasoline, aromatics, LPG and other high-value products, and increases the economic benefit of about 58.2241 million yuan per month.

EFFECT OF UITRASOUND ON MOLECULAR STRUCTURE OF RESIN AND ASPHALTENE IN RESIDUE

2025, 56(4):  70-76. 

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This paper mainly studies the causes and the mechanisms of how ultrasonic waves affect and change the resin and the asphaltene in residue. The results show that initial temperature of ultrasoinc operation has the greatest effect on the distribution of the saturate, aromatic, resin, asphaltene, and the ultrasoinc power takes the second, while operation time has no distinct effect. According to the infrared spectroscopic analysis, the types of functional groups of asphaltene and resins do not change significantly, merely the contents change slightly. Proton nuclear magnetic resonance analysis show that free heteroatoms produced from resin cyclize with the side chains on asphaltene surface and heterocyclic unsaturated compounds are formed on asphaltene structure at low temperature and low power, thus these effects are conducive to asphaltene polymerization. High temperature and high power promote the aromatic structure of asphaltene to open the ring and form side chain, which is favorable for asphaltene cracking. The aromatic compounds of the resin pyrolysis is adsorbed on its surface, while there is a certain limit to this adsorption at high temperature and high power.

EFFECT OF ALKALI TREATMENT ON CATALYTIC PERFORMANCE OF ZSM-11 FOR XYLENE ISOMERIZATION

2025, 56(4):  77-85. 

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ZSM-11 zeolite was synthesized by dynamic crystallization method and treated with different intensity of alkali to obtain the modified samples. The physical and chemical properties of the samples before and after alkali treatment were characterized and compared by using XRD,N₂ adsorption-desorption,XRF,NMR,SEM,NH₃-TPD and Py-FTIR. The results showed that part of the skeleton siliconation of the ZSM-11 zeolite could be removed by alkali modification, changing the crystal morphology and crystallinity of samples, and a certain amount of mesoporous was introduced, forming a more interconnected hierarchical pore structure,which increased the specific surface area. Alkali treatment also could modulate the acid amount of ZSM-11 with more exposed acid sites which significantly enhance isomerization activity. The catalytic performances of the samples were evaluated by using m-xylene isomerization. The results showed that ZSM-11 treated with 0.5 mol/L NaOH solution exhibited the best enhancement in m-xylene isomerization activity.

CHARACTERIZATION OF DEPOSITED CARBON ON SPENT CATALYST OF LONG-TERM OPERATED RESIDUE HYDROGENATION INDUSTRIAL UNIT

2025, 56(4):  86-91. 

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In the process of residue hydrogenation, the feed passes through the bed of protective catalyst and demetal catalyst in turn, intercepting mechanical impurities, removing most of the metal elements, and then enters the bed of transition catalyst and desulfurization catalyst. Carbon deposition is an important cause of inactivation of catalysts. The spent catalyst in long-term operated residue hydrogenation unit was collected, and the carbon deposition characteristics of the catalystswere investigated using a combination of thermogravimetric analysis and mass spectrometry. It was found that the burning temperature of deposited carbon increased significantly with the logistics direction, indicating that the carbon deposition formed on the catalyst gradually changed from soft carbon to hard carbon with the increase of residue hydrogenation depth along the logistics direction. The result of X-ray photoelectron spectroscopy analysis showed that the carbon deposits could be divided into C in the sp² form, sp³ form, and C in the C—O or C=O structure. The electron probe X-ray microanalysis showed that the distribution of carbon deposits on the catalyst was uniform.

INDUSTRIAL SIDESTREAM TEST OF A NOVEL CATALYST FOR ETHYLBENZENE PRODUCTION VIA DRY GAS VAPOR-PHASE ALKYLATION

2025, 56(4):  92-97. 

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A 1.0 kt/a industrial sidestream unit was built by simulating the alkylation reaction unit process of an industrial ethylbenzene plant in a refinery. Taking the new nano-ZSM-5 molecular sieve catalyst HC-501 as the research object, the performance of gas-phase alkylation of catalytic cracking dry gas and benzene was investigated. The catalyst loading method corresponds to the single-stage reaction bed layer of the industrial unit. The test results show that under the conditions of a reaction temperature of 330—370 °C, a molar ratio of benzene to ethylene (referred to as benzene-ethylene ratio) of 20—24, and an ethylene mass space velocity of 0.20—0.50 h^-1, the ethylene conversion rate is greater than 99.8%, the selectivity of ethylbenzene (including ethylbenzene and diethylbenzene, the same below) is greater than 99.0%, and the mass fraction of the main by-product xylene is less than 800 μg/g. Referring to the process conditions of the existing industrial unit, an energy consumption calculation model was established by using the simulation software Aspen Hysys to study the energy consumption under different temperatures and different benzene-ethylene ratios. The results show that for the existing industrial unit, when the benzene-ethylene ratio of the single-stage bed is reduced to 20—24 by using the catalyst developed in this study, the energy consumption of the alkylation + benzene circulation unit can be reduced by 12%—20%.

SYNTHESIS OF Sn-DOPED CERIUM MOLYBDATE AND ITS OXIDATIVE DESULFURIZATION PROPERTIES

2025, 56(4):  98-106. 

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Sn-doped cerium molybdate[Ce(MoO₄)₂] catalysts were synthesized using a reflux method, with ammonium molybdate, stannous chloride, and cerium nitrate hexahydrate serving as reactants. The structures of the catalysts were subsequently analyzed using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy, among other characterization techniques. The results demonstrated that tin was successfully doped into cerium molybdate. The removal of dibenzothiophene (DBT) from a simulated oil was investigated using a Sn-doped cerium molybdate catalyst in the presence of oxygen as the oxidant. It was demonstrated that the doping of Sn ions led to an increase in the concentration of oxygen vacancies in the catalyst, resulting in a 23% enhancement in the desulfurization rate in comparison to the undoped catalyst. After a series of experiments, the optimal reaction conditions were determined to be: 5.0% Sn doping, a reaction temperature of 120 ℃, a catalyst addition of 0.05 g, and an oxygen flow rate of 150 mL/min. Under the optimal conditions, the desulfurization rate reached 98.7%. The catalyst demonstrated the ability to be recycled for five cycles, exhibiting minimal reduction in oxidative desulfurization activity. The desulfurization mechanism of the catalyst was investigated through free radical capture experiments.The results showed that superoxide radical [.O₂^-] was the main active species in the oxidative desulfurization reaction.

DEVELOPMENT OF ENVIRONMENTALLY FRIENDLY CATALYTIC CRACKING MULTIFUNCTIONAL ADDITIVE

2025, 56(4):  107-113. 

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In order to inhibit the poison of heavy metals to catalytic cracking catalysts and improve product distribution, a simple, efficient and environmentally friendly multifunctional additive for catalytic cracking was successfully developped with non-toxic components. The action mechanism of the multifunctional additive was studied by TPR, BET, XRD and other methods, and the performance of the additive was further investigated in the catalytic cracking unit with riser reactor. The results showed that the additive can inhibit Ni contamination because its effective components undergo lattice substitution with Ni²⁺, slowing down the formation of Ni⁰; and the effective components can interact with V₂O₅ to generate highly thermally stable compounds, weakening the migration of V₂O₅ within the catalyst pores and the damage of vanadium acid to the catalyst structure. This multifunctional additive, used in catalytic cracking unit, can reduce the dry gas yield by 0.4 percentage point, hydrogen yield by 15.8%, coke yield by 1.09 percentage points, and heavy oil yield by 0.45 percentage point. At the same time, the gasoline yield increased by 2.18 percentage points and the overall light oil yield increased by 2.87 percentage points. It showed good effect of inhibiting nickel and vanadium contamination and improving product distribution.

STUDY ON THE KINETICS OF PYROLYSIS REACTION OF MIXED PLASTICS

2025, 56(4):  114-122. 

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Three types of plastic particles, polypropylene (PP), high-density polyethylene (HDPE), and polystyrene (PS), were selected and mixed in different proportions, and the thermogravimetric apparatus was used to analyze the pyrolysis temperature range and weight loss of the separate and mixed samples of the three types of plastics. Friedman, KAS and finite parallel reaction model were used to solve the pyrolysis reaction kinetic parameters of plastics. The results demonstrated that the order of pyrolysis reactions of several plastic samples from easy to difficult and the order of average activation energy calculated by Friedman and KAS method from small to large of several plastic samples followed: PS＜PP-PS＜PP-HDPE-PS(1:1:1)＜HDPE-PS＜PP-HDPE-PS(actual proportions)＜PP＜PP-HDPE＜HDPE. The activation energies of PP, HDPE, PS, PP-HDPE, PP-PS, HDPE-PS, PP-HDPE-PS(1:1:1) and PP-HDPE-PS (actual proportions) plastic samples estimated by the finite parallel reaction model were concentrated in the range of 198–314, 231–317, 192–297, 200–314, 194–299, 186–301, 171–242 and 196–312 kJ/mol, respectively.

NUMERICAL SIMULATION ON MICROMIXING EFFICIENCY IN MICROREACTORS

2025, 56(4):  123-131. 

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To analyze the internal information in microreactors, numerical simulations of the micromixing process in a T-type round tube, a T-type square tube, and a square Y-type microreactors were carried out using computational fluid dynamics (CFD) methods. The results simulated by Laminar-Finite-Rate model were consistent with the experimental data reported in the literature, which demonstrated the accuracy and reliability of the chosen CFD model. The flow field, velocity distribution, distributions of H⁺ and I₂, and the distribution of the segregation index X_S of each microreactor in the Villermaux-Dushman reaction system were analyzed, which provided a reference for the evaluation of the micromixing efficiency in microreactors. The results showed that the flow of fluids in all three microreactors was laminar, and H⁺ was quickly and completely consumed in the T-type round tube microreactor, whereas it was always present in the T-type square tube and Y-type square tube microreactors. The segregation index X_S was small in all three microreactors, which showed excellent micromixing efficiency.

FIRST-PRINCIPLES CALCULATION OF HYDROGEN SENSITIVITY OF DOMESTIC FOURTH-GENERATION ZIEGLER-NATTA CATALYST

2025, 56(4):  132-139. 

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Based on the Density Fundtional Theory(DFT),a Ziegler-Natta catalyst molecular model was established,the adsorption on the catalyst surface was calculated, and the adsorption sites and dominant internal electron donors were studied that can improve the hydrogen modulation sensitivity of the catalyst by simulating the adsorption mechanism. The results show that the Mg atom on the complete MgCl₂ crystal plane is mainly composed of 5 coordinations, without redundant active sites, which is not conducive to the chemical adsorption of TiCl₄. TiCl₄ has chemical adsorption at the single atomic defects on the β crystal (110) crystal plane and the β crystal (100) crystal plane. Among them, the adsorption energy at the single atomic defects on the β crystal (110) surface is generally higher than that at the atomic defects on the β crystal (100) surface, with more charge transfer and more stable adsorption. Although the diatomic defects on the β-crystalline (100) surface can provide more active adsorption sites, the adsorption capacity of the surface for TiC1₄ does not increase accordingly. TiC1₄ is more inclined to adsorb in the single-atom surface defect structure on the (100) surface to form a dichloro bridge. On the β-crystalline (110) surface, the configuration of diatomic defects is more conducive to the adsorption of TiC1₄. The Cl atom in the Ti-Cl bond replaces the Cl atom position in the original complete surface to form a new Mg-Cl bond with the Mg atom, thereby forming an active center. The calculation results of the internal electron donor show that the adsorption energy of diisobutyl phthalate on both surfaces is higher than that of ethyl benzoate, making it more suitable as an internal electron donor for the catalyst.

THEORETICAL STUDY ON PROPERTY OF BR?NSTED ACID SITES OF HEUO MOLECULAR SIEVE

2025, 56(4):  140-147. 

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The acid properties of Bronsted acid (B acid) sites in molecular sieves are key factors influencing their catalytic performance. Using H-modified EUO-structure molecular sieve (HEUO molecular sieve) with a silica-to-alumina ratio [n（SiO₂）/n（Al₂O₃）] of 110 as a model system, the acid strength, structural characteristics, and electronic properties of B acid sites in HEUO molecular sieve were investigated using the density functional theory (DFT) calculation method. The results indicate that the T7 site is the most favorable position for Al atom substitution, and B acid sites within the channels exhibit similar acid strengths and structural properties. The B acid site at the T5 position is influenced by surrounding framework oxygen atoms, leading to an elongated O—H bond, an increased Si—O—Al bond angle, enhanced positive charge on the H atom, and reduced negative charge on the O atom. Orbital analysis reveals that the HOMO orbital energy at the B9 site is significantly higher than that of other B acid sites, resulting in a smaller HOMO-LUMO energy gap compared to other sites. This work elucidates the intrinsic characteristics of B acid sites in HEUO molecular sieve at the quantum-chemical level, providing theoretical insights into their acid properties.

COMPARATIVE STUDY ON ATOMIZATION CHARACTERISTICS OF GAS-LIQUID NOZZLE

2025, 56(4):  148-153. 

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The atomization effects of the throat nozzles was tested through cold model experiments, and the atomization characteristics of the throat nozzles, bubble atomization nozzles, and swirl bubble atomization nozzle was compared and analyzed. The results showed that：the spray particle size decreases with the increase of the mass ratio of gas to liquid (referred to as gas-liquid ratio), and increases with the increase of distance; the spray speed increases with the increase of gas-liquid ratio and decreases with the increase of distance; the spray droplets from the throat nozzle are evenly distributed on the sector, and the spray droplets of the bubble atomization nozzles appears zoning on the sector. The operation stability of the swirl bubble atomization nozzle was poor, and the gas distribution pipe was blocked after using for a period of time. The droplet size, particle size distribution of thebubble atomization nozzles and swirl bubble atomization nozzled,and the spray speed were better than those of the throat nozzles. The conclusions obtained can provide basic experimental data for developing energy-saving and efficient atomizers with low gas-liquid ratio and small particle size.

EFFECT OF NEGATIVE PRESSURE DIFFERENTIAL ON THE PERFORMANCE OF CATALYSTS TRANSPORT IN THE STANDPIPE OF INDUSTRIAL FLUID CATALYTIC CRACKING UNIT

2025, 56(4):  154-159. 

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The downflow section of the catalyst circulation in fluid catalytic cracking (FCC) units is characterized by dense phase transport within the standpipe, exhibiting complex flow behavior. The standpipe operates under a negative pressure differential due to the pressure balance between the reactor and the regenerator, with the outlet pressure being higher than the inlet pressure. This negative pressure differential is a design parameter, and due to its fixed nature, there is limited scope for adjustment by industrial field technicians, resulting in scarce reports on related design and research. This study measured the axial pressure distribution in the negative pressure differential standpipe under various operating conditions in an industrial FCC unit and employed CPFD software to investigate the effects of standpipe pressure differential on axial pressure, particle concentration, and catalyst circulation rate. The findings revealed that the lower section of the negative pressure differential standpipe was susceptible to plug flow, leading to a reversal of axial pressure. Simulations indicated that the negative pressure differential impeded catalyst discharge in standpipe, increased particle storage, and enhanced pressure buildup within the standpipe. Conversely, a positive pressure differential resulted in less particle degassing, and as the positive pressure differential increased, particles in the standpipe tended towards a more uniform dense phase flow, leading to an increase in standpipe pressure buildup and catalyst circulation rate. These research outcomes could inform the design and operational adjustments of standpipe.

STUDY ON THE CARBON FOOTPRINT ASSESSMENT OF PRODUCTS FROM CATALYTIC REFORMING UNIT

2025, 56(4):  160-166. 

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The carbon footprint assessment for the products from catalytic reforming unit is of great significance for constructing carbon footprint system for the refining industry and the economy and society. As the energy utilization status of the petrochemical process unit is an important factor affecting carbon emissions, the carbon footprint assessment based on the energy status evolution of product materials in the process of catalytic reforming unit was studied. The assessment method which includes building a process flow, establishing an emission source list, analyzing material balance, emission distribution, and carbon footprint calculation was proposed. The products carbon footprint was calculated by taking a 1.0 Mt/a catalytic reforming unit as a case study. Due to the different processing flow for different products, their carbon footprint will vary greatly. Among them, the by-product hydrogen has a higher carbon footprint of 1613.079 kg/t, while benzene and toluene have carbon footprints of 359.957 kg/t and 428.924 kg/t, respectively; meanwhile, the carbon emissions calculated from the product carbon footprint have good consistency with that calculated from the emission source inventory.

SIMULATION AND OPTIMIZATION OF DIVIDING WALL COLUMN APPLIED IN THE PRODUCTION OF PENTANE FOAMING AGENT

2025, 56(4):  167-176. 

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Using the unit that produces pentane foaming agent from light naphtha and produces liquefied petroleum gas (LPG) as a byproduct as the research object, the conventional double column (DC) process, upper dividing wall column (DWC-U) process, middle dividing wall column (DWC-M) process, and feed preheated middle dividing wall column (FP-DWC-M) process were designed. Using total annual cost (TAC), CO₂ emissions (E_CO2), and thermodynamic efficiency (η) as objectives, the second-generation non-dominated sorting genetic algorithm (NSGA-II) was employed for multi-objective optimization of process parameters to obtain Pareto front solutions. The results indicate that the application of DWC and feed preheating can improve economic and environmental benefits and reduce component remixing within the distillation column. The FP-DWC-M process offers the best economic and environmental benefits, with TAC and E_CO2 reductions by 14.3% and 23.8%, respectively, compared to the DC process.