Table of Content

12 February 2021, Volume 52 Issue 2

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INDUSTRIAL APPLICATION OF SECOND-GENERATION LTAG TECHNOLOGY

2021, 52(2):  1-6. 

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To further improve the octane number of gasoline and reduce hydrogen consumption, the second generation LTAG (LTAG-Ⅱ) technology was implemented on 3.50 Mt/a FCCU and 3.90 Mt/a RDS unit in SINOPEC Shanghai Petrochemical Company Limited. The calibration results of industrial application shows that the apparent conversion of light fraction from vacuum tower cutting LCO into light and heavy fractions and heavy fraction after hydrocracking is 74.12%. The gasoline and LPG selectivity reached about 88%. Compared with blank calibration, the yields of gasoline and LPG increased by 1.47 percentage points and 3.37 percentage points, respectively with 5.50 percentage points reduction of LCO yield in FCCU. Compared with the first generation LTAG technology of LCO full fraction hydrotreating, RON and MON of the stable gasoline increased by 0.6 and 0.7 units respectively. Hydrogen consumption rate of LCO hydrogenation reduced by 22.70%. LTAG-Ⅱ has significant economic benefits.

EFFECT OF HYDROCRACKING REACTION PARAMETERS ON YIELD AND PROPERTIES OF JET FUEL FRACTION

Mo Changyi Zhao Guangle Zhao Yang Ren Liang Qian Jizhi Hu Zhihai

2021, 52(2):  7-11. 

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In order to satisfy the quality demand of jet fuel fraction from hydrocracking unit by adjusting reaction conditions，the effect of reaction parameters of hydrocracking temperature，hydrogen pressure，volume velocity and volume ratio of hydrogen to oil on jet fuel yield and properties were tested using intermediate-base gas oil as feedstocks in single stage once through mode in a hydrocracking device packed with two catalysts in series. The result showed that the jet fuel fraction yield was affected by conversion rate of gas oil under different reaction conditions, the higher the conversion rate of wax oil above 350℃, the higher the jet fuel yield, and that at the same conversion ratio under different hydrogen pressure, the jet fuel fraction smoke point was effected by aromatic saturation extent，while the effects of other reaction conditions on the smoke point were all related to the conversion depth of gas oil feedstock.

INDUSTRIAL PRACTICE OF JOINT OPTIMIZATION OF DIESEL HYDROGENATION UNIT AND HYDROCRACKING UNIT FOR REDUCING DIESEL AND INCREASING JET FUEL

2021, 52(2):  12-16. 

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In order to meet the market demand, the joint optimization of the diesel hydrofining unit and hydrocracking unit was carried out by mixing the middle distillate of diesel hydrofining unit into feed of hydrocracking unit. The results showed that after optimization, the yield of the diesel product decreased by 6.78 percentage points, the flash point (closed) increased from 65 ℃ to 77.5℃，the kinematic viscosity increased from 3.010 mm²/s to 3.540 mm²/s, and the yield of jet fuel increased by 5.08 percentage points, meeting the expected targets of improving diesel quality, reducing diesel and increasing jet fuel production.

EFFECTS OF INJECTED MEDIUM ON DELAYED COKING PROCESS

2021, 52(2):  17-21. 

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The effect of different injected medium on the product distribution and product properties of delayed coking was investigated. The results of pilot test showed that when the injected medium of 1% steam was replaced by the same amount of methane, ethane or propane, the product distribution was nearly equal under the conditions that the feed rate, furnace outlet temperature, operating pressure, circulation ratio and coking period were basically the same. When the amount of methane injection raised from 1.04% to 1.96% and 4.02%, the yield of coker gas oil increased by 1.16 and 3.44 percentage points, respectively, and the yield of liquid products increased by 0.75 and 2.19 percentage points, respectively. With the increase of methane injection, the properties of coker gasoline and coker diesel were basically the same, but the properties of coker gas oil became worse. The density, residual carbon and asphaltenes content all increased, and its 95% point of the distillation range increased by 21.9 oC. Moreover, when the injection mass of steam and methane was the same, methane was more conducive to retard the furnace tube coking than steam.

OPERATION OPTIMIZATION OF AROMATIC COMPLEX UNIT

2021, 52(2):  22-26. 

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As the high-load operation of the reforming unit was resumed to increase hydrogen production to meet the demand of hydrogenation unit, and the output of reformate oil also increased. At the same time, as the chemical and chemical fiber market was in a downturn, the aromatics complex unit of SINOPEC Luoyang Company adopted the operation mode of "pumping up extraction load and lowering load of p-xylene":The reformate pre-fractionation unit and liquid-liquid extraction unit operated at high load, while the disproportionation unit of xylene unit was stopped; and the isomerization unit, xylene fractionation unit and adsorption separation unit operated with low load; optimizing the processing mode of the extraction unit inside the plate and the toluene production process, shutting down the o-xylene tower, optimizing the C₈ aromatics external rejection process and the operation parameters of the heavy aromatics tower. By comprehensive adopting the above measures, the energy consumption and material consumption of the aromatics complex unit were effectively reduced, and the monthly cost reduction and efficiency increase were realized by 1.82 million Yuan per month.

PRODUCT DISTRIBUTION OF MIXTURE OF 1-HEXENE AND n-HEXANE OVER DIFFERENT ZEOLITE CATALYSTS

2021, 52(2):  27-32. 

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The cracking tests of the mixtures of 1-hexene and n-hexane with different mass ratio (based on 1- hexane mass fraction) on ZRP, Beta, DASY and REY zeolite catalysts were carried out in a fixed fluidized bed reactor at 500℃ to investigate the rule of cracking products distribution. The contribution factors of 1-hexene to n-hexane conversion on four zeolite catalysts were calculated, and the effects of different mass ratios of model compounds on the selectivity of olefins, alkanes, isomeric hydrocarbons and aromatics were expounded. The results showed that on the same catalyst, with the increase of 1-hexene content in the model compound, the selectivity of alkanes and olefins showed an opposite trend, indicating the reaction is competitive. The selectivity of isomerization products on the four catalysts increased as the 1-hexene/n-hexane ratio increased, and the order of the selectivity was DASY-L≈REY-L＞Beta-L＞ZRP-L, which has a good corresponding relationship with the pore size of the four catalysts. 1-Hexene in the model compound promoted the aromatization reaction, but the aromatics selectivities of the four catalysts were low. The results showed that the selectivity of aromatics is related to the acid amount and strength of catalyst, the higher the acid amount and the smaller the acid strength, the higher the selectivity of aromatics.

THEORETICAL STUDY ON ISOBUTENE POLYMERIZATION OVER SULFONIC ACID RESIN IN PRESENCE OF ETHANOL

2021, 52(2):  33-38. 

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The polymerization of isobutene over sulfonic acid resin in the presence of ethanol was studied using DFT theory and B3LYP/6-31G (d, p) algorithm method. The activation energies of the etherification reaction of ethanol and isobutylene and the polymerization reaction of isobutylene are 62.8 kJ/mol and 167.8 kJ/mol, respectively. Compared with the polymerization reaction of isobutylene, the reaction energy barrier of the etherification reaction is lower and the reaction will take place preferentially. The physical adsorption energy of ethanol on benzenesulfonic acid is -71.3 kJ/mol, and the physical adsorption energy of isobutylene on benzenesulfonic acid is -44.8 kJ/mol. The physically adsorbed isobutylene is easily protonated by the H of the sulfonic acid group to form alkoxy intermediate with chemical adsorption energy of -80.2 kJ/mol. Finally, the mechanism of ethanol in the isobutene polymerization system was analyzed.

EFFECT OF RATIOS OF Y MOLECULAR SIEVES TO AMORPHOUS SILICA-ALUMINUM ON DIESEL HYDROCRACKING CATALYSTS

2021, 52(2):  39-45. 

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Ni-Mo hydrocracking catalysts were prepared by incipient-wetness impregnation method using different proportions of modified Y molecular sieve and amorphous silica-aluminum as acidic components. The catalysts were characterized by N₂ adsorption-desorption, NH₃-temperature programmed desorption, pyridine adsorption infrared spectroscopy, X-ray diffraction and H₂-temperature programmed reduction. The hydrocracking performance of the catalysts was investigated in a fixed-bed reactor with mixed diesel fraction as raw material. The results showed that with the increase of the content of modified Y molecular sieve, the amount of B acid and the ratio of B/L acid in the strong acid range of the catalyst increased first and then decreased. When the content of molecular sieve was too high, the active components were accumulated. At the mass ratio of modified Y molecular sieve to amorphous silica-aluminum of 1.0, the catalyst had moderate specific surface area and pore size, and the active components were well dispersed with the highest amount of B acid in the strong acid range, and the largest ratio of B/L acid. When the catalyst with the mass ratio of Y molecular sieve to amorphous silica-aluminum of 1.0 was used in diesel hydrocracking, the catalyst exhibited the highest activity.So there was the highest conversion efficiency of aromatics in diesel oil, the highest conversion rate of fractions above 250℃, the lowest yield of tail oil and the lowest BMCI.The yield sum of heavy naphtha and jet fuel was the highest, and the aromatic hydrocarbon potential content of heavy naphtha was the highest.

EFFECT OF INDUSTRIAL CALCINATION CONDITIONS ON PORE PROPERTIES OF ALUMINA CARRIERS

2021, 52(2):  46-50. 

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The effects of carrier roasting furnace type, mesh belt running frequency, carrier bed thickness, roasting temperature, modified gas flow rate and converter pre-roasting temperature on the pore properties of alumina carrier were investigated. The results showed that the specific surface area of alumina carrier calcined by converter was smaller, the volume distribution ratio of the pore diameter of 2-6 nm was low, while the volume distribution ratio of the pore diameter of 6-20 nm was high. Without gas modification, the carrier calcined in mesh belt kiln had a larger specific surface area, but the volume distribution ratio of the pore diameter of 2-6 nm was relatively high and the volume distribution ratio of the pore diameter of 6-20 nm was relatively low. With proper gas modification and other process condition optimization, the volume distribution ratio of the pore diameter of 2-6 nm could be reduced and the volume distribution ratio of the pore diameter of 6-20 nm increased. The optimized process conditions of mesh belt kiln were as follows: roasting temperature (benchmark +15)℃, electricity frequency (benchmark +2)Hz, material layer thickness (benchmark +8)cm, modified gas amount (benchmark+20)m³/h. When the carrier was roasted in converter, it could be optimized by adjusting the pre-roasting temperature. When the pre-roasting temperature was (benchmark +140)℃, the volume distribution ratio of the pore diameter of 6-20 nm could reach 91.22%.

SILICON DEPOSITION LAW ON COKING NAPHTHA HYDROGENATION CATALYST AND FUNCTION OF SILICON TRAP CATALYST FHRS-2

2021, 52(2):  51-56. 

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In order to study the silica deposition rule on catalyst bed in coking naphtha hydrogenation unit and verify the protective effect of FHRS-2 silicon trap catalyst, a 2000h simulated operation test was carried out. In addition, the influence of silica deposition on the pore properties of the catalyst was investigated by means of XRF，XRD，XPS，N₂ adsorption-desorption，and the conversion process of silicone-bearing species before and after catalyst regeneration was speculated. The experimental and analytical results showed that the deposition of silicon in the catalyst beds of coking naphtha hydrogenation unit did not decrease uniformly, and in the first and second bed the deposition amount was relatively high. The sensitivity of specific surface area of catalyst to silicon deposition was higher than that of pore volume and pore size. Based on the experimental results, it is speculated that the silicon-containing substance (cyclosiloxane) reacts on the catalyst surface in the high temperature region; and SiO₂ is generated and deposited in the catalyst pore canal during the regeneration process. The activity of main catalyst in downstream can be effectively protected and the operation cycle of coking naphtha hydrogenation unit can be prolonged by loading silicon trap catalyst FHRS-2 in grading mode.

COMPARISON OF TWO C₈ AROMATICS ISOMERIZATION CATALYSTS IN AROMATICS COMPLEX UNITS

2021, 52(2):  57-61. 

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The loading, drying, start-up of C₈ aromatics isomerization catalysts,RIC-200 and RIC-270 ,in two proprietary aromatics complex units in SINOPEC Hainan Refining& Chemical Co. were introduced, and the performance of the two catalysts were compared. The results showed that compared with RIC-200 catalyst, RIC-270 catalyst was better in isomerization activity and ethylbenzene conversion rate, which could make the unit produce more p-xylene.

PRACTICE OF LONG-TERM OPERATION OF PRT-C/PRT-D REFORMING CATALYST

2021, 52(2):  62-66. 

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The industrial application of semi-regenerative reforming catalyst PRT-C/PRT-D developed by SINOPEC Research Institute of Petroleum Processing in a 500kt/a catalytic reforming unit of Dushanzi Petrochemical Company of PetroChina was introduced. After 1 263 days long-term operation in the first cycle of PRT-C/PRT-D, using the feed with aromatics potential content of 52.30%, under the reaction conditions of space velocity of 1.04 h-1 and a weighted average bed temperature of 452.9 ℃, the stable gasoline yield was 87.12%, the aromatics yield was 57.93%, and the total pressure drop of the reactor was only 44.9 kPa. After the first off-site regeneration, the PRT-C/PRT-D catalyst had been operated for 1 474 d in the second cycle. Using the feed with aromatics potential content of 49.40%, under the reaction conditions of a weighted average bed temperature of 461.6 ℃ and a space velocity of 1.38 h-1, the yield of gasoline was 91.00%, the aromatics yield was 59.33%, and the total pressure drop of the reactor was only 53.1 kPa. The catalyst showed good regeneration performance, good activity, selectivity and stability.

EFFECT OF ANTIMONY DOPING ON DENITRATION PERFORMANCE OF Mn-Ce/TiO₂ CATALYST

2021, 52(2):  67-72. 

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A series of Sb doped Mn-Ce-Sb/TiO₂ catalysts was prepared by impregnation method. The effect of Sb/TiO₂ molar ratio on the denitration performance of the catalysts was investigated. The catalysts Mn-Ce/TiO₂ and Mn-Ce-Sb/TiO₂ (Sb/TiO₂ molar ratio 2∶10) were characterized by XRD, BET, NH₃-TPD and H₂-TPR, and the denitration performance, sulfur resistance and water resistance of the two catalysts were compared. The results showed that Sb doping was beneficial to the dispersion of active components on the support, to the interaction between active components and support and the low temperature redox reaction. In addition, Mn-Ce-Sb/TiO₂ (2∶10) catalyst has larger specific surface area, more surface acidic sites and excellent redox performance. Therefore, compared with Mn-Ce/TiO₂ catalyst, Mn-Ce-Sb/TiO₂ (2∶10) catalyst has better SCR activity of NO_X, better resistance to sulfur and water.

DETERMINATION OF VOLATILE ORGANIC COMPOUNDS IN PETROCHEMICAL SOILS USING PURGE-AND-TRAP-GC-MS METHOD

2021, 52(2):  73-79. 

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A method was established for determination of 59 volatile organic compounds (VOCs) in soils by gas chromatography-mass spectrometry with purge-and-trap pretreatment. The effects of pretreatment conditions such as purging temperature, purging time and desorption time were investigated. The detection limits were 0.1-5.0 ng/g, and the recoveries of spiked sample were in the range of 68.7%-128.7% with RSD of 0.9%-12.5% (n=6), indicating that the method is suitable for the analysis of VOCs in soils．From the analysis results of actual petrochemical soil samples, it can be concluded that most of the samples belong to low concentration petrochemical soil samples and can be determined directly by purge-and-trap and gas chromatography-mass spectrometry; Very few high-concentration petrochemical soil samples need to be pretreated by methanol extraction-extraction solution injection; However, in addition to standard methods, it is necessary to develop new analytical methods for soils containing unidentified alkanes, and aromatic hydrocarbons above C9.

STUDY ON DISTINCTIVENESS OF FUEL ECONOMY TEST METHODS FOR LOW VISCOSITY GASOLINE ENGINE OIL

2021, 52(2):  80-84. 

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With the tightening of current energy-saving and emission regulations, the energy-saving of engine oil has attracted more and more attention by automobile manufacturers. GF-6 gasoline engine oil specifications put forward higher requirements for energy saving, and it is not widely representative to use a bench to evaluate the energy saving performance of lubricating oil used for various engines. Therefore, a set of evaluation methods that can accurately evaluate the energy saving of gasoline engine oil was established for a certain type of 4-cylinder engine, and bench tests were carried out, and the results of friction performance of different oil formulations were compared with those of SRV simulation tests. It is concluded that the established bench test method has good distinctiveness and repeatability, and is suitable for evaluating the fuel economy of low viscosity gasoline engine oil.

EFFECTS OF ADDITIVES ON STRAY GASSING OF OIL-PAPER COMPOSITE UNDER THERMAL STRESS

2021, 52(2):  85-91. 

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In order to study the real gassing characteristics of transformers in operation, effects of base oil,antioxidant DBPC and metal deactivator Irgamet39 on stray gassing of oil-paper composite insulation at 120 ℃ were studied. The test results showed that stray gassing of oil-paper was largely influenced by additive types, oil oxidation, insulation pressboard thermal degradation, and insulation pressboard adsorption. Antioxidant DBPC could greatly reduce the content of hydrogen and hydrocarbon gas in oil-paper insulation system by inhibiting the aging of insulating oil. However, DBPC could also promote the aging of insulating paperboard to produce more CO and CO₂. The metal deactivator Irgamet39 produced a higher amount of hydrogen in the oil-paper insulation system, and showed a sharp downward trend, compared with the amount of hydrogen produced by pure oil, which was considered to be caused by the adsorption of metal deactivator on the insulation board. At the same time, Irgamet 39 could promote the pressboard aging leading to more CO and CO₂, while Irgamet39 made no obvious influence on hydrocarbon gas.

APPLICATION OF FRICTION IMPROVER IN HEAVY DUTY DIESEL ENGINE OIL

2021, 52(2):  92-96. 

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With the development of logistics industry and infrastructure industry, the requirements for heavy truck fuel economy are constantly improving. Four heavy duty diesel engine oils CI-4 15W-40, which meet the quality standards of GB/T 11122—2006, were prepared by using paraffin-based lubricating base oil produced by CNOOC (Taizhou) Petrochemical Co. Ltd. as raw materials, adding a certain amount of compound additives, viscosity index improvers, organic molybdenum friction improvers, polymer friction improvers. The effects of friction modifiers on physical and chemical properties, anti-wear and extreme pressure properties and driving performance of heavy duty diesel engine oil were mainly investigated. The results showed that it took time for the organic molybdenum friction modifier to display the effect at low temperature, and the polymer friction modifier could significantly improve the extreme pressure performance. There was a synergistic effect between the two friction modifiers, which could improve the fuel economy of vehicles by 1% - 2% in driving test.

SIMULATION AND OPTIMIZATION FOR ATMOSPHERIC AND VACUUM DISTILLATION UNIT FOR COAL TAR

Ye Qiliang Xi Maohua Yang Jingyi Yuan Peiqing

2021, 52(2):  97-101. 

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Coal tar is widely used, but its composition is extremely complex. The complex coal tar system was characterized by combining real components with virtual components as model system, and the atmospheric and vacuum distillation process of coal tar was simulated and calculated by using chemical process simulation software Aspen Plus V9.0. The effects of reflux ratio, number of theoretical trays, side position of extraction, and feeding position on product quality were analyzed. The results showed that under the optimized process conditions, the mass fraction of phenol in light oil fraction reduced to 0.5%; the mass fraction of phenol in the phenol oil fraction reached 42.4%, while the mass fraction of naphthalene decreased to 9.5%. The mass fraction of naphthalene in naphthalene oil fraction reached 85.0%. The mass fractions of phenol and naphthalene in the wash oil fraction decreased to 0.11% and 2.6%, respectively, and the product quality was significantly improved.

DEVELOPMENT OF WATER ELECTROLYSIS TECHNOLOGY AND IT’S APPLICATION IN GREEN HYDROGEN PRODUCTION

2021, 52(2):  102-110. 

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Green hydrogen produced by renewable power such as wind power and photovoltaic power meets the requirements of energy development in the new era. Renewable power is characterized by intermittence, fluctuation and randomness, which puts forward higher requirements for water electrolysis technology. The key to the development of electrolytic water technology lies in materials. This topic reviews the development of hydrogen production technology by alkaline water electrolysis and proton exchange membrane pure water electrolysis from the aspects of oxygen evolution electrocatalyst, electrolyte, membrane material and diffusion layer material, and introduces the application and development status of hydrogen production technology by renewable power, and analyzes the existing technical problems, and puts forward some suggestions on the research and development of electrolyzed water and green hydrogen technology by renewable power for the future.

INFLUENCING FACTORS ON GUM FORMATION IN LIGHT OIL DURING STORAGE

2021, 52(2):  111-120. 

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This review intends to summarize the effects of oil compositions, type of process, and storage conditions on gum formation. The rate of gum formation has a significant relationship with the hydrocarbon compositions, among which olefins have the greatest effect. Traces of nitrogen-containing compounds, sulfur and its derivatives, metal ions and unsaturated hydrocarbons in fuels react with each other, playing a catalytic role on the gum formation and leading to color change. The gum content is also affected by external factors such as temperature, oxygen content, storage time, light, water content, and metal ion concentration. Different types of additives and the depth of hydrogenation reaction inhibit or promote the actual gum formation. It is proven that gum formation is the result of a combination of multiple factors. Hydrofining, improved storage conditions or adding appropriate additives can all decrease the rate of gum formation and extend the storage time of oil products. In view of the fact that nitrogen content is more sensitive to changes in actual colloidal content, attention should be paid to the nitrogen content in the oil. As fiber reinforced plastic storage tanks have many advantages, such as corrosion resistance, good mechanical seal, good thermal insulation, and UV protection. They are beneficial to improve oil stability when used for long-term storage of oil products. Regarding the research and application of oil stability, on the one hand, we should have a good command of the mechanisms of gum formation from the aspects of reaction kinetics and colloidal chemistry; on the other hand, we should strengthen storage oil quality analysis and make use of big data and artificial intelligence technology to acquire the main influencing factors of gum formation so as to provide theoretical support for practical applications.