Table of Content

12 March 2022, Volume 53 Issue 3

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RESEARCH AND DEVELOPMENT OF GREEN SUPPLY CHAIN TECHNOLOGY FOR THE FULL LIFE CYCLE OF HYDROGENATION CATALYSTS

2022, 53(3):  1-8. 

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The hydrogenation catalyst developed by SINOPEC Research Institute of Petroleum Processing meets the needs of full hydrogenation refinery companies. At the same time, based on the requirements of national and industrial environmental protection regulations, the concept of a green supply chain for the full life cycle of hydrogenation catalysts has been proposed. Technology development has been carried out, such as green production of carrier precursor and hydrogenation catalysts, e-Trust(ex-situ Truly sulfiding technology for hydrotreating catalyst), off-site regeneration,and cascade utilization of spent catalysts. Among these technologies, green production of carrier precursor and hydrogenation catalysts as well as off-site regeneration have been industrialized for many years. e-Trust technology has been industrialized in 2018. The regeneration of spent residue hydrogenation and cascade utilization of spent distillate hydrogenation catalyst has been made great progress. The green supply chain technology for the full life cycle of hydrogenation catalysts can not only ensure the production of green and high-value products during the industrial application of hydrogenation catalysts, but also guarantee the use or future use of green environmental technologies in process of catalyst production, start-up and shut down of refinery plant. It can comprehensively help the efficient and environmentally-friendly use of resources and promote the green and healthy development and sustainable development of the entire oil refining industry.

EFFECT OF BIMODAL PORE STRUCTURE ON THE PERFOEMANCE OF RESIDUE HYDROTREATING CATALYSTS

2022, 53(3):  9-15. 

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Three types of bimodal supports with gradient distribution of the most probable macropore diameter and macropore volume ratio were prepared as catalysts, and the effect of bimodal pores on the physicochemical properties and performance of the catalyst was investigated. The results show that the metal dispersion on the catalyst is lower than that of the residue hydrotreating carbon residue catalyst prepared by single peak pore support. Because of the reduction of the specific surface area of the bimodal pore carrier and the decrease of the number of hydroxyl groups, the interaction between metal and the support is weak, and the average length of the sulfided active phase and the average number of stacked layers are high. With the decrease of the ratio of the volume of macropores to total pore volume, the activity of the catalyst for desulfurization and carbon residue removal increases.

DEVELOPMENT AND PERFORMANCE EVALUATION OF HYDROISOMERIZATION CATALYST WITH HIGH SELECTIVITY

2022, 53(3):  16-21. 

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According to the reaction mechanism of n-paraffin hydroisomerization, a new hydroisomerization catalyst was developed for the isomerization of linear alkanes. The catalyst used a special acidic component to promote the reaction molecules to approach the reaction active site and the isomerization of intermediate products to quickly detach from the reaction active site. The results of physical and chemical properties characterization revealed that the new molecular sieves and catalysts had larger pore volume, larger pore diameter and weaker acidity than the contrast molecular sieves and catalysts. The results of the evaluation experiments using two types of industrial hydrocracking tale oil and F-T wax as the feeds showed that using new catalyst could get higher target product yield and less loss of viscosity index than the contrast catalyst, and it could adapt to different raw feed oil. Specially, the activity and isomerization selectivity of the new catalyst were higher when F-T wax was the feed.

IMPACT OF WATER AMOUNT AND SEED CRYSTAL ON SAPO-11 MOLECULAR SIEVE SYNTHESIS AND ISOMERIZATION PERFORMANCE

2022, 53(3):  22-30. 

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A series of SAPO-11 molecular sieves were synthesized by adjusting the n(H₂O)/n(Al₂O₃) ratio, the amount of seed crystals addition and crystallization temperature in the SAPO-11 molecular sieve synthesis process, and the effects of synthesis conditions on the physicochemical properties of molecular sieves and the catalytic performance in 1-hexene hydroisomerization were studied. The results show that the preferential growth of SAPO-11 molecular sieves can be obtained by increasing ratio of n(H2O)/n(Al2O3), thus exposing more pores and improving the catalytic performance, and the size of SAPO-11 molecular sieve can be reduced by adding heterogeneous crystal seeds. Compared with the molecular sieves synthesized under other conditions, the specific surface area, pore volume and acid content were increased. The SAPO-11-seed-200 molecular sieves synthesized at high n(H2O)/n(Al2O3) ratio, heterogeneous seeds and high crystallization temperature had the smallest particle size, the largest specific surface area and pore volume, and the highest acid amount. The catalytic activity and the skeletal isomerization selectivity of 1-hexene isomerization were better than those of other molecular sieves.

CONTROL METHOD OF SPHERICITY SIZE AND PARTICLE SIZE DISTRIBUTION OF FCC CATALYST

2022, 53(3):  31-36. 

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The drying principle of the droplet in the spray forming process of FCC catalyst was studied, and the reason for the formation of irregular particles and fine powder with diameter less than 40 μm were analyzed. A new structure spray nozzle was designed to control the formation of irregular particles and reduce the formation of fine powder. The new structure spray nozzle could introduce cold air around the material-liquid conical atomization layer (fog cone) in the spray drying column, and cut off the direct contact between the slurry atomization droplets and the high-temperature atmosphere entering the column. A relatively mild drying environment was established for atomizing droplets. Compared with the conventional operation, the number of irregular particles was obviously reduced and the sphericity of the catalyst particles was obviously improved with the highest value of 0.941 ( raised by 0.013). At the same time the yield of the catalyst under the spray drying column was increased by 5.2 percentage points, and the production of fine powder was reduced by about 1 percentage point.

COMMERCIAL APPLICATION OF DEEP CATALYTIC CRACKING CATALYST FOR HIGH PROPYLENE AND LOW COKE

2022, 53(3):  37-40. 

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The commercial application of DMMC-3, a new special catalyst for catalytic cracking with characteristics of high propylene and low coke, developed by SINOPEC Research Institute of Petroleum Processing, has been carried out in the catalytic cracking unit of CNOOC Ningbo Daxie Petrochemical Co. The calibration results showed that the propylene yield and propylene concentration in LPG were increased by 0.56 and 1.74 percentage points , respectively. Compared with the previous generation of DMMC-2 catalyst, coke was decreased by 0.1 percentage point, in addition to increasing the concentration of ethylene in dry gas. The DMMC-3 catalyst could improve the yield and selectivity of propylene, reduce coke formation and increase the economic benefit of the unit.

DEVELOPMENT AND COMMERCIAL APPLICATION OF HIGH EFFICIENCY HYDRODEWAXING TECHNOLOGY FOR DIESEL DISTILLATES

2022, 53(3):  41-45. 

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According to the composition of diesel distillates and hydrocarbon reaction characteristics，combining the principle of heat release from hydrogenation reaction and heat absorption of hydrodewaxing reaction, by optimizing the grading combination of hydrotreating catalyst and hydrodewaxing catalyst, SINOPEC Dalian Research Institute of Petroleum and Petrochemicals has developed a high-efficiency diesel distillates hydrodewaxing technology. The results of industrial application in a 0.6 Mt/a hydrodewaxing unit showed that the temperature distribution of the catalyst bed in the hydrodewaxing reactor is reasonable and the inlet temperature is reduced by 25 ℃. Compared with the conventional hydrodewaxing technology used in the last cycle, the yield and cetane number of the main product No.－35 low condensation point diesel were increased. The hydrogen consumption and energy consumption of the unit were reduced by more than 10%，which could meet the energy saving and consumption reduction goal of the refinery, and the economic benefits of the unit was greatly improved.

INDUSTRIAL PRACTICE OF RECYCLE REFINING KEROSENE FRACTION THROUGH LTAG NOZZLES IN FCC UNIT

2022, 53(3):  46-50. 

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The effects of rerefining of kerosene fraction injected through LTAG nozzle into FCC unit on product distribution and product properties were investigated in SINOPEC Shijiazhuang Refining and Chemical Company. The results show that the yields of dry gas, LPG and gasoline are increased, the feed quantity, feed composition and main operating conditions of FCC unit are kept stable, and the yields of diesel, slurry and coke are decreased after the rerefining jet fuel fraction. The (C₃+C₄) alkane content of the LPG product was increased, (C₃+C₄) olefin content was decreased, when the feed amount of heavy oil was kept at about 210 t/h, compared with the blank working condition without recycle. The aromatics volume fraction of the product gasoline was decreased by 0.2 percentage point and 0.5 percentage point under the conditions of rerefining kerosene fraction 11.2 t/h and 21.1 t/h, respectively; the volume fraction of benzene was increased by 0.05 percentage point and 0.07 percentage point, respectively; and RON was decreased by 0.2 and 0.6, respectively.

OPTIMIZATION OF OPERATION SCHEME FOR PRODUCTION OF ULTRA-LOW SULFUR CLEAN DIESEL

2022, 53(3):  51-55. 

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The difficulties existing in the process of producing ultra-low sulfur clean diesel and their effects on the economic benefit and long-term operation of the refinery were analyzed for improving the flexibility of optimizing and adjusting the production plan of the whole plant. On this basis, through a series of measures, such as adjusting the diesel cutting point of delayed coking unit, optimizing the feedstock ratio of diesel hydrotreating unit, reducing the output of FCC slurry, adjusting the load of VGO hydrotreating unit and hydrocracking unit, optimizing the operation of atmospheric and vacuum furnaces, etc., the service life of catalyst in the diesel hydrotreating unit was prolonged to over four years. By calculation, the total output of gasoline could be increased by 107 kt/a, the fuel gas could be saved by 1 200 t/a, and the hydrogen consumption could be reduced by 1 500 m³/h.

INDUSTRIAL PRACTICE OF TRANSFORMER OIL PRODUCTION BY REVAMPING DIESEL HYDROGENATION UNIT

2022, 53(3):  56-61. 

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Using the first vacuum side stream of SZ36-1 as raw material, the feasibility of producing transformer oil base oil was verified in a pilot plant industrial trial production at the diesel hydrogenation unit of CNOOC Taizhou Petrochemical Co., Ltd. without changing the process flow. When the fresh feed rate was 25 t/h, the product circulation rate was 15 t/h, the volume space velocity was 0.96 h^-1, the reaction pressure was 7.0 MPa, the inlet temperature of the reactor was 345 °C, and the volume ratio of hydrogen to oil was 600, the product transformer oil basic oil could meet the general physical and chemical properties requirements of transformer oil quality index (GB 2536- 2011) . The calculation results of the process parameters of the industrial unit show that the diesel hydrogenation unit can be used to produce transformer oil base oil with little modification of equipment.

APPLICATION OF CRYOGENIC METHANATION TECHNOLOGY IN HYDROGEN REFINING FOR POLYPROPYLENE IN REFINERY

Liang Feng

2022, 53(3):  62-66. 

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The cryogenic methanation technology was studied to replace the commonly used PSA technology to refine hydrogen for polypropylene raw material, and the technical scheme was designed and put forward. BC-H-10 catalyst was used to remove CO from refinery industrial hydrogen to provide raw material for polypropylene by cryogenic methanation technology with low-temperature heat source in refinery. The results show that the CO impurity content in industrial hydrogen can be reduced to less than 0.1 μL/L steadily at the conditions of reaction pressure of 1.8 MPa, temperature of 150-155 ℃ and catalyst loading of 0.1 m³. The scale of cryogenic methanation is 300 m³/h, and the hydrogen yield is 99%, which is higher than the original PSA process. The cryogenic methanation technology can save investment and land occupation, reduce operation cost and increase efficiency by 3.5 million yuan per year.

RADIAL BED REACTOR MODEL FOR ISOMERIZATION OF C₈ AROMATICS

2022, 53(3):  67-72. 

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A radial bed reactor model for the isomerization of C8 aromatics was developed by applying a six-component sequential reaction network. Based on industrial data, the simulated annealing algorithm was used to fit the reaction rate constants of the reaction network, and the concentration distributions of all components could be obtained for reversible and irreversible reaction networks. The results showed that the calculated values of the model fit the industrial data very well, and the relative error was small. By comparing the concentration distribution data of the two reaction networks, the reversible reaction network was closer to the real industrial process. Based on reversible reaction network model, the effect of space velocity on reaction results was calculated. It was found that the lower space velocity could lead to increase of by-products, and the higher space velocity could lead to decrease of PX.

KINETICS OF XYLENE ISOMERIZATION CATALYZED BY SKI-210 CATALYST

2022, 53(3):  73-78. 

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The kinetics of xylene isomerization catalyzed by SKI-210 catalyst was studied in a fixed bed reactor. The reaction network consists of a consecutive reaction between three xylene isomers and a disproportionation of xylene. The first order kinetics model based on Langmuir adsorption was selected and the reaction rate constants and adsorption equilibrium constant were obtained by using the initial rate method at different reaction temperatures. The conversion calculated by the model is in good agreement with the experimental data, and the model can be used to describe the effect of reaction conditions on the yield of p-xylene.

EFFECT OF COMPOSITION OF HYDROGENATION SYSTEM ON ASPHALTENE HYDROGENATION

2022, 53(3):  79-84. 

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Asphaltene extracted from atmospheric residue of Yumen crude and atmospheric residue of Venezuela crude were hydrogenated in residue system and decalin system respectively. The hydrogenation effects of the two asphaltenes in different systems were comprehensively investigated from three aspects: the distribution of hydrogenation products, the removal rate of heteroatoms, and the condensation degree of asphaltene after hydrogenation. The results show that in the decalin system, the yield of light products from asphaltene hydrogenation is higher and the yield of coke is lower than those in residue system, but the removal effect of impurities is poor, and in residue system, the coke yield of asphaltene hydrogenation is higher and the removal effect of impurities is better than those in decalin system, and asphaltene has a higher degree of condensation. The main reason is that decalin can dissolve and disperse asphaltene, and provide hydrogen for the hydrogenation process, which can improve the distribution of asphaltene hydrogenation products, slow down the tendency of asphaltene condensation and reduce the formation of coke. The coke formed by the condensation of the heavy oil component macromolecules in the residue system is helpful for the removal of sulfur and nitrogen heteroatoms through the formation of coke.

MODELING OF STAKED TWO-STAGE REGENERATION SYSTEM IN FCC UNIT

2022, 53(3):  85-90. 

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In order to solve the problem of complex and difficult to optimize the operation of staked two-stage regeneration system in FCC unit, a model of staked two-stage regeneration system was established, and the simulation of the regeneration system was carried out. The results show that it is more advantageous for the first regenerator to use lower amount of main air to obtain better regeneration effect when the total amount of main air is constant. For the staked two-stage regeneration unit, under the optimized operating conditions, the total main air consumption is 9.5m³ per kilogram of coke, which can make the carbon content of the regeneration agent lower than 0.05%.

STUDY ON ADSORPTION REMOVAL OF PYRIDINE FROM MODEL FUELS BY THREE KINDS OF ACTIVATED ALUMINA

2022, 53(3):  91-98. 

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The pyridine in the model fuel（n-dodecane solution of pyridine） containing nitrogen with mass fraction of 1 732 μg/g was adsorbed by alkaline, acid and neutral alumina, respectively. To determine the best adsorbent, the effects of various adsorption factors on the adsorption efficiency were investigated. The results indicated that the best adsorption effect was obtained by using 1.2 g alkaline alumina at 303 K for 30 min when the 15 mL model fuel was adsorbed, and the nitrogen removal rate was 61.24%. Adsorption behavior of pyridine in simulated fuel by alkaline alumina accords with the Langmuir-Freundlich hybrid model. The adsorption process can be carried out spontaneously and belongs to exothermic physical adsorption, and accords with quasi-first-order kinetic model equation. After high temperature calcination or ethanol washing, the regeneration rates of the adsorbents were 72.04% and 71.48% respectively, which showed that alkaline alumina had good regeneration performance.

CHARACTERIZATION OF FUNCTIONAL GROUPS AND HYDROGEN BOND OF ASPHALTENES FROM PETROLEUM AND COAL TAR BY INFRARED SPECTROSCOPY

2022, 53(3):  99-103. 

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The functional group structure of asphaltenes from coal tar and petroleum residue was characterized by Fourier transform infrared spectroscopy. The hydrogen bond region, aliphatic C—H stretching vibration region and C—O region were fitted by software Origin 2018. The results show that the two asphaltenes are mainly composed of carbon and hydrogen, and the content of heteroatoms in the two asphaltenes is obviously different, but the types of heteroatom functional groups are basically the same. The hydrogen bonds in coal tar asphaltenes are formed by the self-association of O atoms and O atoms in aromatic ether bonds, and the hydrogen bonds of coal tar asphaltene are formed by O atom in aromatic ether bond and O atom in benzene ring. The alkyl side chains of coal tar asphaltenes are shorter than that of residue asphaltene.

^,MEASUREMENT OF POLYOXYMETHYLENE DIMETHYL ETHERS PRODUCTS COMPOSITION BY GAS CHROMATOGRAPHY

2022, 53(3):  104-109. 

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A gas chromatography method for determination of polyoxymethylene dimethyl ethers products composition was developed. The relative mass correction factors of methanol (MeOH), methyl formate (MF), trioxane (TOX) and polyoxymethylene dimethyl ethers (PODE_n,n≤3) were determined by using ethylene glycol diethyl ether as internal standard. From dimethoxymethane (DMM), PODE2 and PODE3 used as primary standard materials, the relative mass correction factors of PODE4-10 components were extrapolated. The relative mass correction factors of hemiacetal (HF_n) were calculated by effective carbon number method. The results of precision and recovery showed that the relative standard deviations were less than 2.0%, and the recovery rate ranged between 99%-104%, which could meet the requirements of the quantitative analysis for polyoxymethylene dimethyl ethers product from different water content of raw materials.

INDUSTRIAL EXPERIMENT OF ENHANCED PRETREATMENT TECHNOLOGY FOR REFINERY SPECIAL WASTEWATER

2022, 53(3):  110-116. 

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The refinery special wastewater has become an environmental problem for enterprises due to its poor water quality and difficulty of treatment. Aiming at the water quality characteristics of the special wastewater, a set of enhanced pretreatment process and pilot plant of “oil separation-flotation-electrochemical oxidation-neutralization- filtration” were designed. The results of 186 days on-site operation showed that the compliance rate of effluent COD, petroleum, and suspended solids concentration was 100%, the compliance rate of ammonia nitrogen concentration was 97.8%, and the average B/C increased to 0.334, and the water quality could meet the acceptance requirements of the integrated wastewater treatment plant. The removal rates of ammonia nitrogen and total nitrogen in the electrochemical oxidation unit were up to 96.5% and 93.3%, respectively, and the B/C value of the wastewater was increased by 67.0%. The processing cost was low, and an average operating cost was 4.56 yuan/m³.

RESEARCH PROGRESS OF FIXED-BED RESIDUE HYDRODEMETALLIZATION CATALYSTS

2022, 53(3):  117-124. 

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Residue hydrodemetallization (HDM) catalyst is one of the key catalysts in residue hydrogenation technology. Development of high-performance HDM catalysts is of great significance for improving the adaptability of inferior raw material and extending the operation period of the fixed bed residue hydrotreating unit. The research progress of HDM catalysts is reviewed from three aspects of supports, active metals and promoters. Firstly, the influence of support pore structure on HDM catalysts was analyzed, and various pore-enlarging methods of Al2O3 support such as pore-enlarging additives method, hydrothermal treatment method and low-temperature sintering method were introduced. Secondly, after comparing the HDM activity of various active metal components, Mo shows the best hydrodemetallization performance. The addition of Co, Ni, Fe, W and other active metals can further improve the catalytic performance of the HDM catalyst to various degrees. Preparation methods of catalysts such as impregnation method, kneading method and co-precipitation method were summarized. Finally, the influence of P, B and other promoters on the activity and stability of HDM catalyst was discussed. It is pointed out that the main research direction of HDM catalyst in the future is to improve hydrodemetallization activity, metal-storage capacity, resistance to coking and reduction of catalysts bulk density.