PETROLEUM PROCESSING AND PETROCHEMICALS

OPTIONS OF SELECTIVE HYDRODESULFURIZATION PROCESS SCHEME FOR TREATING FCC GASOLINE

Pan Guang-Cheng,Hong Nie

2010, 41(5): 1-6. doi:

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A variety of hydrodesulfurization process schemes for treating FCC naphtha was discussed and compared. It is found that cutting FCC naphtha into a light naphtha fraction (LNF) and a heavy naphtha fraction (HNF) treating respectively can significantly reduce the rate of olefin saturation during hydrodesulfurization process. The mercaptans in LNF can be removed by alkaline extraction and the olefin content of LNF is not affected significantly. Adding a reactor to selectively remove diene in HNF is necessary, due to the formation of gum is promoted by diene under relatively mild conditions. The existence of hydrogen sulfide in recycle hydrogen may suppress hydrodesulfurization reactions and promote olefin saturation, thus a system for removing hydrogen sulfide in recycle hydrogen is required. The mercaptans in product can be removed by fixed-bed oxidation. Finally, based on the above findings, considering the feedstock properties, reaction kinetics and commercial requirements, a selective hydrodesulfurization process scheme is determined.

REFORMER BENZENE REDUCTION THROUGH FEED PREFRACTIONATION

Ma Aizeng,jianqiang ren

2010, 41(5): 7-9. doi:

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The pathways of benzene formation in reformate were reviewed and reducing benzene content of reformate by feed prefractionation approach was discussed. It was concluded that the benzene reduction efficiency of this approach depended on the removal rate of benzene precursors in feed. Enhancing the operation temperature of prefractionator, most of the benzene molecules and benzene precursors could be removed, thereby the benzene content of reformate was decreased significantly, yet fully eliminated benzene in reformate could not be achieved. By increase the number of plates in prefractionator to enhance the fractionation efficiency could be a feasible way to improve benzene reduction.

APPLICATION OF QUALITY TRANSFER METHOD TO INCREASE GASOLINE YIELDS

Tao Xie,xianyao liang,Baifu Xu

2010, 41(5): 10-13. doi:

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In order to meet the demand of increase gasoline yield, based on the routine ways to enhance gasoline yield, quality transfer method was introduced in production processes at the Refinery of Maoming Branch, SINOPEC. Increase margin was found among the complex oil blending, operation control of processing unit and quality management to ensure obtaining qualified gasoline product and increase gasoline yield simultaneously.

STUDY ON THE DESULFURIZATION OF CATALYTIC CRACKED DIESEL BY OXIDATIVE EXTRACTION

Song peng-jun,kejian LIAO

2010, 41(5): 14-18. doi:

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This paper studied the combined desulfurization process of catalytic oxidation and solvent extraction for FCC diesel fractions by using hydrogen peroxide, formic acid and NMP as oxidation agent, catalyst and extraction agent, respectively. The influences of the amount of catalyst, reaction time, oxidation temperature, the pressure of oxygen and the amount of extraction agent on the sulfur removal rate were investigated. Test results showed that under the optimum conditions of a reaction temperature of 80 ℃, an oxidation time of 90 min, an oxygen pressure of 0.6 MPa and a catalyst to oil volume ratio of 0.1, the sulfur content of the treated diesel oil was reduced to 190.8 µg/g from the original 1 694.2 µg/g, the sulfur removal rate reached 88.7％. Then using a volume ratio of NMP to oil of 1.0, three times extraction at room temperature and further adsorption by silica gel, the yield of finished diesel fuel was 94%, and its sulfur content was 37.5 µg/g, which could well meet the requirement of European Emission Standard IV (less than 50 µg/g).

PROBLEMS AND COUNTERMEASURES IN LONG-TERM RUNNING CCR UNIT

2010, 41(5): 19-24. doi:

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Some problems occurred during the long-term running of a 1.39 Mt/a CCR unit in Yangzi Petrochemical Company were summarized. Countermeasures were applied and these problems were solved, such as using low coke rate catalyst to solve the bottleneck of catalyst regeneration; using desilication adsorbent to reduce the silicon content of feedstock; controlling the catalyst fines in reactor-regeneration system to avoid emergency shut down; recovering waste heat from stack gas, alkali-washing heat exchanger and online water-washing depentanizer to enhance equipment running efficiency; adopting technology innovation including putting elastic washer on the high-temperature flange of reactor and remodeling the scallop structure of the fourth reactor.

APPLICATION OF MPTA TYPE DEMETALLIZATION AGENT IN CRUDE ELECTRIC DESALTING

2010, 41(5): 25-29. doi:

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The effect of MPTA agent on the demetallization of Daqing and Jidong mixed crude oil was evaluated in laboratory, and the commercial trial was carried out in the electric desalting device of the No.2 atmospheric-vacuum distillation unit at Beijing Yanshan Company, SINOPEC. The results of batch scale lab test showed that good demetallization performance could be obtained at a MPTA added dosage of 80 μg/g. The commercial test results showed that at a MPTA added dosage of 60 μg/g, the removal rates of calcium, sodium, magnesium, iron and nickel were 82.20%, 98.96%, 91.90%, 58.65% and 24.23%, respectively. Meanwhile, the acid value of treated mixed crude oil could be less than 0.5 mg KOH/g without significant change.

STUDY ON THE HYDROGENATION PROCESS OF USING COMPOSITE OILS FOR PRODUCING PLANT WAX

2010, 41(5): 30-33. doi:

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The effect of hydrogenation conditions over copper-nickel catalyst and the palm oil to soy bean oil ratios on the melting point and needle penetration degree of product were studied. Results showed that under the optimal process conditions of a palm oil to soy bean oil weight ratio of 1, a reaction pressure of 0.5 MPa, a reaction time of 60 min, a reaction temperature of 240℃ and a catalyst dosage of 0.04%, the melting point and the needle penetration degree of the hydrogenated composite oils were 47.3℃ and 55/0.1mm, respectively.

MODIFICATION OF Y ZEOLITE CONTAINING COMPOSITE MATERIAL AND ITS CRACKING PERFORMANCE

Zhou Ji-Hong

2010, 41(5): 34-38. doi:

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A Novel Structure zeolite Y (NSY) composite was modified by twice rear earth exchange and calcination. The crystal structure, surface area, pore volume, chemical compositions, thermal stability and hydrothermal stability of the modified samples were characterized by X-ray diffraction, X-ray fluorescence spectrometer, N2 adsorption, DTA and MAT techniques. Modified samples having various rear earth contents were used to prepared FCC catalysts, the catalytic performances of these catalysts were evaluated using fixed-fluidized bed (FFB) device. Test results showed that modified samples having higher rare earth content exhibited better residue cracking ability and higher light oil yield; modified samples having lower rare earth content exhibited better coke selectivity and higher LPG yield.

EFFECT OF THE CONTINUOUS PREPARATION OF CATALYST SLURRY GEL ON THE CATALYST PERFORMANCE

Tian zhihong,Zhoujian,lvlufeng,xuefeng li

2010, 41(5): 39-42. doi:

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A continuous preparation technology for catalyst slurry gel was developed by Research Institute of Petroleum Processing and it was realized at a FCC catalyst pilot plant. Comparative tests between continuous technology and intermittent technology of FCC catalyst slurry gel preparation were carried out using a same catalyst formula. Results showed that the particle size of slurry gel prepared by continuous method were smaller; the catalyst prepared by continuous technology exhibited higher mechanical strength, lower attrition resistance index and better catalytic performance, i.e. coke yield was 0.41 percentage points lower, microactivity and conversion was 3 percentage points higher and 1.35 percentage points higher, respectively. Besides, the consumptions of energy and water of the continuous slurry gel preparation were also lower.

PREPARATION OF COMPOSITE TITANIUM-ZIRCONIUM OXIDES AND THEIR APPLICATION IN HYDRODESULFURIZATION CATALYST

LI Hui-Yuan

2010, 41(5): 43-47. doi:

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TiO2, ZrO2 and composite titanium-zirconium oxides with various Ti to Zr molar ratios (4:1, 3:2, 1:1, 2:3 and 4:1) were prepared by coprecipitation method, and active components (10% MoO3) were impregnated on these supports to form relative catalysts. These catalysts were characterized by X-ray diffraction, nitrogen adsorption and their hydrodesulfurization activities were evaluated using a high-pressure reactor. Results showed that after calcination at 550 ℃ for 2 h, TiO2-ZrO2(1:1), TiO2-ZrO2(2:3) and TiO2-ZrO2(3:2) supports were all amorphous, the other two supports exhibited certain crystallization. In comparison with the single metal oxide, mixed oxides had larger surface areas, among them the surface area of TiO2-ZrO2(1:1) was the largest (191.2 m2/g). Thiophene hydrodesulfurization was taken as the model reaction for evaluating the HDS activities of these catalysts. It was found that HDS activities increased with the increase of zirconia content in mixed oxides and a maximum activity was observed for the 10% MoO3/TiO2-ZrO2(1:1) catalyst. With further increase of zirconia content, the catalytic activities decreased and the minimum activity belonged to the catalyst using ZrO2 support.

EFFECT OF IMPREGNATING SULFURIZING AGENT CONDITIONS ON THE PRESULFIDED CATALYST

2010, 41(5): 48-52. doi:

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A sulfurizing agent was prepared by mixing sulfur with sulfided olefin, which was prepared from FCC gasoline and sulfur. Presulfided hydrofining catalysts were impregnated by this sulfurizing agent, and the effect of impregnation conditions on the sulfur content, sulfur retention rate and catalyst broken rate of the presulfided catalyst was investigated. The presulfided catalyst was activated by gas-phase batch sulfurization. Experimental results indicated that impregnation scheme by using a pre-mixing sulfur and sulfided olefin mixture with a sulfur to sulfided olefin (based on sulfur content) molar ratio of 1 was preferred. The optimum impregnation conditions were as follows: the amount of mixed sulfurizing agent should be 1.4 times of the theoretical sulfur requirement for catalyst to be fully sulfurized, impregnating at 170℃ for 3 h, the sulfur to sulfided olefin molar ratio (based on sulfur content) should be 1. Sulfur content and sulfur retention rate of presulfided catalyst added addition agent was higher than that of without addition agent. Comparison tests between in-situ and ex-situ sulfidation of catalyst were carried out on a 100 mL hydrotreating device and the results showed that the activities of catalysts by in-situ and ex-situ sulfidation were almost the same.

EFFECT OF MOLECULAR STRUCTURE, CHARGE DISTRIBUTION AND ALKALESCENCE OF IMIDAZOLE AND ITS DERIVATIVES ON ACID REMOVAL RATE OF HIGHLY ACIDIC CRUDE OIL

Ben-xian Shen

2010, 41(5): 53-57. doi:

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The molecular structure modeling of imidazole and its derivatives was calculated by ab initio calculation method. The charge distribution of the optimal configuration was obtained. The NMR data of the calculated optimal configuration was in accordance with the actual operation data by nuclear magnetic resonance spectroscopy, which indicated that the built optimized molecular structure of imidazole and its derivatives was reasonable. According to the calculations of the molecular charge distribution, the alkalescence order of imidazole and its derivatives from strong to weak was in the order of 2-methylimidazole > 2-ethylimidazole > imidazole > 1-methylimidazole. Their pH values in aqueous solution and deacidification performance were determined. It was found that their pH values and acid-removal rates increased with the increase of alkalescence.

KINETICS STUDY OF THE ESTERIFICATION ON SILICA-SUPPORTED FERRIC SULFATE CATALYST

2010, 41(5): 58-61. doi:

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The silica-supported ferric sulfate [Fe2(SO4)3/SiO2] catalysts were prepared by impregnating SiO2 in ferric sulfate aqueous solution followed by calcination in air at high temperature. The effects of calcination temperature, loading amount of ferric sulfate, the amount of catalyst used, reaction time and reaction temperature on the synthesis of ethyl oleate were investigated. Results showed that Fe2(SO4)3/SiO2 was an efficient solid catalyst for the esterification of oleic acid and ethanol under solvent-free condition. The kinetic study of the reaction was carried out by an integral method and using an equivalent proportion of the reactants under atmospheric pressure. It was also found that the experimental data were in good agreement with the reaction mechanism proposed by Langmuir-Hinshelwood model. The experimental data fitted the pseudo second-order rate equation. The apparent activation energy and the pre-exponential factor were calculated to be 50.40 kJ•mol−1 and 1.22×107(mol/L)-1•h-1, respectively.

PROCESS OPTIMIZATION FOR RECOVERING COLD ENERGY OF NATURAL GAS SHALLOW CONDENSING UNIT

2010, 41(5): 62-65. doi:

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Taking the shallow condensing unit of Daqing Oilfield Natural Gas Company as an example, the current cold energy recovery situation of light hydrocarbon and export dry gas of shallow condensing unit was analyzed. Some existed problems and measures of improvement were put forward. Various schemes for improvement were compared based on the simulation computations by HYSIM software. Finally, a cold energy recovery process using multi-flow heat exchanger was proposed. After adopting said optimized process, when the recovery temperature of light hydrocarbon and export dry gas was 10℃, 263.6 MJ/h of cold energy could be recovered, the temperature of rich natural gas was decreased to -1.94℃ from 5℃, the load of ammonia evaporator reduced by 20.4％, the annual saving of electricity and production cost reached 60.61×104 kWh and 0.477 MRMB, respectively.

STUDY ON THE CATALYTIC WET OXIDATION OF REFINING WASTEWATER WITH COPPER-BASED CATALYSTS

2010, 41(5): 67-70. doi:

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A series of copper-based catalysts having four metal components were prepared by co-precipitation method and the structure of the catalyst was characterized by XRD. The refining wastewater was treated by copper-based catalysts and the effects of catalyst preparation conditions including active components ratios and calcination temperatures on the COD removal rate were investigated as well as the wastewater treating process conditions. Results showed that using a Cu-Ni-Zn-Fe catalyst with molar ratios of Cu:Ni:Zn:Fe=1:1:2:1 and calcined at 500 ℃, under the optimal treating conditions of a temperature of 240 ℃, an oxygen partial pressure of 1.8 MPa and a treating time of 60 min, the COD removal rate reached 95.9 % and the catalyst exhibited good stability.

STUDY ON THE PERFORMANCE OF ETHANOL DIESEL FUEL

LIU Xiao,XIONG Yun,XU Shi-Hai,Lin-Jun FAN

2010, 41(5): 71-76. doi:

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Ethanol diesel fuel samples with various ethanol blended ratios were prepared using distillates of 2nd and 3rd atmospheric column side cuts, catalytic cracking diesel fraction, hydrotreated diesel fraction and commercial 0# diesel fuel as base oil respectively. The mutual solubility of ethanol and diesel, physical and chemical properties, longtime stability and engine test performance were investigated. Results showed that the mutual solubility and stability of ethanol and 0# diesel fuel were excellent; the existence of water could significantly affect the stability of ethanol diesel; adding co-solvent could improve the water tolerance of ethanol diesel in some extent. The low temperature performance of diesel fuel was improved a little by adding ethanol. The copper strip corrosion test result of ethanol diesel could meet the requirement of National Standard for diesel fuel, yet its flash point and seal compatibility were dropped a bit. As compared with diesel fuel, the fuel consumption and smoke exhaust of ethanol diesel were similar to those of conventional diesel and its NOx exhaust was lower.

DETERMINATION OF TOTAL ACID NUMBER IN JET FUEL BY POTENTIOMETRIC TITRATION

2010, 41(5): 77-80. doi:

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A method for the determination of total acid number in jet fuel by potentiometric titration is presented. The adding mode of titrant and the determination of endpoint were studied by T50 potentiometric titrator. The effect of nonaqueous electrode and carbon dioxide on the experimental results was analyzed, and the optimal testing conditions were determined. The results of potentiometric titration were compared with those of indicator method, and its deviation was less than the reproducibility limit of indicator method. Repeatability of potentiometric titration was satisfied with Grubbs. Results showed that potentiometric titration was suitable to measure the total acid number of jet fuel, potentiometric titration was more accurate than indicator method especially for measuring colored and low acidic samples.

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