Table of Content

12 February 2020, Volume 51 Issue 2

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ANALYSIS OF LONG -TERM OPERATION OF XYLENE ISOMERIZATION CATALYST RIC-200

2020, 51(2):  1-5. 

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Catalyst is the core of xylene isomerization process, and the stability of the catalyst plays a key role in the long-term operation of the device. The main facts influencing the lifetime of xylene isomerization catalyst are catalyst performance, raw material properties，catalyst regeneration as well as process conditions. Based on the long-term operation of phase 1 aromatics plant of SINOPEC Hainan Refining & Chemical Co.Ltd., the stability of the RIC-200 catalyst was analyzed. The results showed that high initial activity of catalyst, good control of impurity in raw material, stable process of regeneration, reasonable adjustment of process parameters could contribute to the stability of the catalyst. The measures to improve the service life of xylene isomerization catalyst RIC-200 were proposed.

EFFECT OF AGING TIME ON PHYSICAL PROPERTIES OF CATALYTIC CRACKING CATALYST

2020, 51(2):  6-9. 

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The catalytic cracking catalyst was aged for different duration from 2h to 70 h under the conditions of 800℃, 100 % steam and normal pressure in a fixed fluidized bed aging apparatus to investigate the physical properties changes of the catalyst. Eleven aged catalysts with different aging periods were analyzed by XRD, BET, NH3-TPD and Py-IR and MAT. The results showed that as the aging period increased, the relative crystallinities and the specific surface areas of the catalysts decreased rapidly and then slowly; the ratio of weak L acid to B acid and the ratio of strong L acid to B acid increased first and then decreased; the MAT of the catalyst decreased rapidly and then tended to be flat.

DEVELOPMENT OF GREEN TECHNOLOGY FOR ZEOLITE SYNTHESIS

2020, 51(2):  10-15. 

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The sources of ammonia nitrogen and chemical oxygen demand (COD) in wastewater from zeolite synthesis process were analyzed, and the solutions to reduce the discharge of ammonia nitrogen and COD were determined. The preparation process of ZSM-5 was optimized, and the reuse procedure of mother liquor and amine-water mixture was adopted. The mother liquor concentration device was built to apply primary mother liquor and secondary mother liquor from titanium silicalite molecular sieve synthesis process for the synthesis of ZSM-5 zeolite to realize the cascade utilization of waste mother liquors. The preparation of ZSM-5 zeolite using mother liquor from ? zeolite synthesis was also carried out. These results showed that the reuse procedure of mother liquor not only solves the environmental pollution caused by the discharge of waste liquid from the production of zeolite, but also reduces the production cost of ZSM-5 zeolite.

COMMERCIAL APPLICATION OF RAX-3000 ADSORBENT FOR PX SEPARATION

2020, 51(2):  16-19. 

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The Physical and chemical properties and commercial application are mentioned. The 600kt/a PX plant of an enterprise started in operation successfully at the end of 2013 and has been running smoothly since its start-up. The calibration results showed the the average purity and yield of p-xylene were 99.8% and 98.3% ,respectively, which exceeded the guaranteed value of the technical contract.In the production process, the water balance is controlled between 0.8 and 1.0, which is beneficial to improve the adsorption selectivity. Compared with the data of reference agent, RAX-3000 adsorbent has better properties in raw material adaptability, extreme working conditionsand adsorption capacity.

COMMERCIAL APPLICATION OF DENITRATION ADDITIVE TUD-DNS3 IN FCC UNIT

Cai Xiaoqing Tu Anbin

2020, 51(2):  20-24. 

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The commercial application of denitration additive TUD-DNS3 in FCC unit of SINOPEC-SK（Wuhan）Petrochemical Co. Ltd. was introduced. The results demonstrated that when the mass fraction of this additive accounted for 2.6% of total catalyst inventory，the ammonia nitrogen content in the effluent water of flue gas desulfurization unit reduced from 100 mg/L to less than 40 mg/L；the addition of additive lowered the furnace temperature of CO incinerator，and the emission of flue gas was qualified. No adverse effect on the operation of the plant, the product distribution and the qualities of gasoline and diesel products were found.

STRUCTURE AND PROPERTIES OF Ni/Mg-Al CATALYST MODIFIED BY DIFFERENT METAL ELEMENTS

2020, 51(2):  25-30. 

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Using MgO, Al2O3 and ZrO powder as carriers, nickel as active component and cobalt and lanthanum as auxiliary agents, ultra-high temperature ammonia decomposition catalysts were prepared. The structure of which was characterized by XRD, BET, TPR and TEM.To investigate the influence of different metal elements on the structure and performance of catalyst, catalyst evaluation device was used. XRD results show that NiAl2O4 spinel phase exists in all the catalysts; metal elements can promote the crystalline form of NiAl2O4 spinel; compared with Co and Zr, La contributes more to the crystalline form. TPR results show that more crystalline phase of NiAl2O4could be formedafter adding of La, and a stronger interaction with carrier is formed after adding Co. BET and TEM experiment show that La is helpful to improve the dispersion and concentration of Ni species on the catalyst surface, and to form smaller surface nickel particles, so as to improve the active site distribution of nickel. Compared with Ni/Mg-Al and CoNi/ZrMg-Al catalysts, LaNi/ZrMg-Al catalyst shows better high temperature wear resistance, sintering resistance and thermal stability under experimental condition of reaction temperature 1200 ℃, volume space velocity 1228 h-1.

OVERALL SOLUTIONS FOR HIGH EFFICIENT OPERATION OF RHT FIXED BED RESIDUE HYDROTREATING UNIT

Shao Zhicai Liu Tao Deng Zhonghuo Hu Dawei Shen Minghuan Wang Shaobing Dai Lishun Yang Qinghe

2020, 51(2):  31-37. 

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The high efficient operation of RHT unit is greatly influenced by feed properties, fluid distribution in reactor, catalysts and the graded loading technology. The feedstock not only influences the removal rate of hetero-atoms and CCR，but also impose an impact on the deactivation mechanism and the unit operating cycle. The inefficient fluid distribution leads to a higher radial temperature difference in reactor. The catalyst grading schemes can directly influence the activity and stability of the loaded catalysts. The mass transfer and diffusion of the residual are suffered due to the very high molecular weight and viscosity of residual oils. To solve these problems, based on the understanding of these influencing factors and practical operational experience, a series of corresponding RHT technologies were proposed by RIPP: tailored catalysts and grading technologies, crude pre-decalcification technologies, higher-efficient fluent distribution technology, switchable protection reactor technology as well as RICP technologies. According to the properties of feeds and the general process of the whole plant, several overall solutions were proposed for different RHT units. Commercial applications in three plants showed that long-term efficient operations with the overall solutions were realized.

STUDY ON BLENDING CGO AND FCC LCO IN HYDROCRACKER FEED

Shi Jialiang Zhao Guangle Yang Youliang Song Yichang

2020, 51(2):  38-44. 

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The effects of blending FCC LCO or CGO in the feed of a 2.0 Mt/a hydrocracking unit on process parameters, equipment conditions, product properties and energy consumptions were studied. The results showed that compared with LCO, when CGO was used as a blending material, the average temperatures of refining reactor and hydrocracking reactor both increased, while the total temperature rise of the refining reactor reduced; the salt deposition rate of high pressure heat exchanger accelerated. At the same jet fuel yield，total hydrogen consumption was reduced，the qualities of jet fuel and diesel and unconverted oil improved, meanwhile the potential aromatic content of heavy naphtha decreased and the total energy consumption increased. Under those two conditions，good quality naphtha，jet fuel，diesel and unconverted oil can obtained by adjusting process parameters.

STUDY AND INDUSTRIAL PRACTICE ON REDUCING BENZENE CONTENT OF DCC NAPHTHA

2020, 51(2):  45-49. 

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The benzene content of naphtha from DCC unit of Dongfang Petrochemical Corporation Ltd. was high. Being limited by the process flow, in order to reduce benzene content of naphtha, the operation of DCC unit was adjusted baseing on the understanding of mechanism of benzene formation. It is recognized that benzene comes from cracking reaction of side chains in aromatic hydrocarbon , hydrogen transfer reaction of cycloalkane and dehydrocyclization reaction of alkenes. The effects of raw material properties, operation conditions and properties of catalyst on benzene content in naphtha were analyzed. By adjusting the operation conditions，benzene content of naphtha was reduced from 1.60% to 1.40%.

MECHANISM ANALYSIS OF EFFECT OF H2O ON ADSORPTION OF SO2 AND NO ON γ-Al2O3

2020, 51(2):  50-56. 

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The mechanism of the influence of H2O on the adsorption of SO2 and NO on γ-Al2O3 was investigated by molecular simulation and experimental investigation. The adsorption structure of γ-Al2O3 (110C) surface was constructed, and the adsorption models for H2O, SO2, NO molecules on (110C) surface were established to determine the optimized adsorption structure. It was found that there was obvious electron transfer between adsorbate and (110C) Al site by charge density and partial density of states, resulting in the formation of stable adsorption structure. H2O occupied Al3c and O3c sites through molecular adsorption and dissociation adsorption; SO2 was mainly adsorbed at Al3c and Al4c sites, while NO interacted with the Al4c sites and needed to be oxidized at the O3c sites. Therefore, there is a competitive adsorption among H2O, SO2, NO at Al3c and O3c sites on the γ-Al2O3 (110C) surface. The experimental results were basically consistent with the theoretical analysis of molecular simulation. H2O is not conducive to the adsorption of SO2 and NO on γ-Al2O3.

SIMULATED PREDICTION OF ANTIOXIDATION PERFORMANCE OF HYDROTREATING BASE OIL

2020, 51(2):  57-61. 

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Based on the composition characteristics of group II/III base oil, two kinds of neural network models was built with multiple neural network and radial basis probabilistic neural network. A nine parameter neural network model with the oxidation stability as the output variable was established taking the contents of straight chain alkanes, naphthenes, alkyl benzenes and viscosity index of the hydrotreated base oil as input variables. For the first time, the viscosity index was used as the input parameter of the prediction model, which greatly improves the prediction accuracy of the model. Based on the analysis of the factors affecting the oxidation stability of hydrotreated base oil, the alkane components of II/III base oil with positive/negative correlation with the oxidation stability were found. With the increase of linear alkanes and the decrease of dicyclic and tricyclic alkanes in II/III base oils with low aromatic, the oxidation stability of base oil increases.

STUDY ON SYNTHESIS AND PHASE TRANSITION OF CYLINDRICAL ALUMINUM AMMONIUM CARBONATE CLUSTERS

2020, 51(2):  62-70. 

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Cylindrical aluminum ammonium carbonate clusters were successfully prepared from γ-Al2O3 powder and ammonium bicarbonate by hydrothermal method. Al2O3 were also prepared from the cylindrical aluminum ammonium carbonate cluster precursor. The effects of reaction temperature, reaction time and material ratio on the morphology of cylindrical aluminum ammonium carbonate clusters and the phase transformation process and the properties of γ-Al2O3 were investigated by XRD, SEM, N2 adsorption-desorption and TEM. The results showed that the optimum reaction conditions were as following: the mass ratio of γ-Al2O3 powder to ammonium bicarbonate of 1:1.75, the reaction temperature 140 ℃, and the reaction time 6 h. The diameter of the synthesized cylindrical aluminum ammonium carbonate clusters was 5-15 μm. The cylindrical aluminum ammonium carbonate cluster was formed by cross-stacking of cylindrical aluminum ammonium carbonate with a diameter of 50-100 nm and a length of 0.5-3 μm. When the calcination temperatures were 600, 800, 1 000，1 300 ℃, aluminum ammonium carbonate clusters were successively transformed to γ，η，α aluminum. The specific surface area of the γ-Al2O3 was 300 m2/g, pore volume was 0.67 mL/g, and more than 50% of the total pore volume was over 15 nm in diameter.

TRIBOLOGICAL PROPERTIES OF POLYANILINE LITHIUM GREASE UNDER CURRENT-CARRYING LUBRICATION

2020, 51(2):  71-75. 

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Conductive polyaniline lithium grease (PANI grease) and silver coating copper material (silver coating material) were prepared. The friction and wear properties of copper based material and silver coating material were investigated by friction and wear testing machine under the conditions of no current-carrying，current-carrying and boundary lubrication. The silver coating material and surface grinding appearence were characterized by XRD, SEM and EDS. The results showed that the silver coating material not only had good antifriction and antiwear properties, but also had stronger conductivity in PANI grease lubrication test under the condition of current-carrying. The excellent antifriction and antiwear properties of the silver coating material were attributed to the dual functions of the protective film and surface softening caused by the current heat effect.

COMPOSITION ANALYSIS OF COLORING SUBSTANCES OF RUSSIAN-MADE 50-1-4Φ AVIATION LUBRICATING OIL UNDER HIGH TEMPERATURE OXIDATION

2020, 51(2):  76-80. 

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In this paper, the high temperature oxidation experiment of Russian-made 50-1-4? aviation lubricating oil was carried out according to ASTM D4636 standard method. The color redness problem of lubricating oil due to oxidation was investigated by an innovative extracting method with aqueous methanol solution and gas chromatography-mass spectrometry (GC-MS). The chromogenic substances were analyzed. The results showed that the antioxidant T531 was the key factor causing the color redness of the 50-1-4? aviation lubricating oil. The chromophores mainly included the antioxidants themselves and the complex derivatives, such as 1-acetyl-3-(6-methyl-3-pyridinyl) -pyrazoline, dibutyl phthalate, and dialkyl phthalate. It is proved that the aqueous methanol solution has an excellent effect on the extraction and enrichment of chromogenic materials in ester oil.

RELATIVE MOLECULAR MASS AND DISTRIBUTION OF PAO WITH GEL PERMEATION CHROMATOGRAPHY

2020, 51(2):  81-86. 

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Poly-alpha-olefin (PAO) is a kind of high-quality based oil of synthetic lubricants. Its relative molecular mass and distribution directly affect macroscopic properties. A method was developed for characterizing the relative molecular mass and distribution of 1-decene oligomer. Gel permeation chromatograph (GPC) equipped with differential refractive index (RI) was used to characterize the relative molecular mass and distribution of PAO. The operation conditions of GPC-RI were optimized, including the flow rate of the mobile phase and the combination of gel chromatographic columns to optimize the separation effect and operability. The operation mode was that the tetrahydrofuran as flow phase with a flow rate of 0.8 mL/min, combination of three columns of Styragel HR0.5, Styragel HR1, and PLGEL 3μm MIXED-E in series to separate PAO. The chromatographic efflux curve was processed by universal calibration method with polystyrene (PS) as the standard sample. Compared with GPC-LLs, the relative deviation for weight average relative molecular mass measures was less than 3%.

FAST DETERMINATION OF ACIDITY AND OTHER PROPERTIES OF DIESEL BY INFRARED SPECTROSCOPY

2020, 51(2):  87-92. 

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To fast determine the acidity and other properties of the automotive diesel, the attenuated total reflection sample cell was used to obtain the infrared spectra of the samples. The IR spectra were further analyzed with partial least squares (PLS) to establish four calibration models, which were used to determine the acidity, density, flash point and freezing point of diesel fuel samples. The validation standard errors were 0.46 mg/(100 mL), 0.77 kg/m3, 2.60 ℃ and 2.77 ℃, respectively. The method meets the requirements of the reproducibility of standard method. Compared with the standard method, the new established method showed the advantages of no pretreatment, simpler process, shorter test time and better repeatability.

STUDY ON TREATMENT OF SIMULATED PHENOL CONTAINING WASTEWATER BY CATALYTIC OZONATION WITH CERAMIC MEMBRANE

2020, 51(2):  93-97. 

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The toxic phenol containing wastewater pollutes the environment and is difficult to treat. The treatment of simulated phenol containing wastewater by catalytic ozonation with ceramic membrane was conducted. The effects of ozone dosage, initial pH, membrane flux and initial phenol concentration on the removal of phenol and the reaction kinetics and mechanism were studied. The results showed that the catalytic ozonation coupled with ceramic membrane was the most effective for removing phenol at ozone dosage of 3.55 mg/min, initial pH of 10.02, membrane flux of 75 L/(m2?h) and initial concentration of phenol of 20 mg/L. After reaction for 45 min, the removal rate of phenol was 100%. The degradation of phenol by the catalytic oxidation coupled with ceramic membrane followed the apparent pseudo-first-order kinetic model. A comparative experiment of TBA (tert-butanol, hydroxyl radical scavenger) proved that the degradation of phenol by the catalytic oxidation coupled with ceramic membrane basically followed the free radical mechanism.

DEVELOPMENT AND APPLICATION OF COMPLETE TECHNOLOGY FOR REDUCING SO2 EMISSION CONCENTRATION OF SULFUR RECOVERY UNIT

2020, 51(2):  98-103. 

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Aiming at the influencing factors on SO2 emission in sulfur recovery unit, the protective measures were established. By the integration innovation of new catalyst and process technology, the LS-DeGAS Plus complete technology for reducing SO2 emission concentration in sulfur recovery unit with independent intellectual property rights was developed. The concentration of SO2 emission in the flue gas of the sulfur recovery unit was reduced to below 50 mg/m3, which meets the requirements of the SO2 concentration specified in the national standard “Petroleum Refining Industry Pollutant Emission Standard” (GB 31570—2015). The technology has the characteristics of no secondary pollution, low investment, low energy consumption and easy implementation. It has been promoted and applied for 58 sets in China.

DISCUSSION ON ENERGY SAVING AND CONSUMPTION REDUCTION METHODS FOR AROMATIC COMPLEX UNIT

Zhuang Liangliang

2020, 51(2):  104-109. 

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Based on the analysis of the development trend of domestic aromatic complex units and the compositions of energy consumptions of four aromatics units in domestic，it was confirmed that the energy consumption lied mainly on factors of fuel，electricity and steam. The energy saving and consumption reduction methods for aromatic units in domestic and abroad were summarized. Based on the practical experience and investigation results, the energy saving and consumption reduction methods of aromatics complex unit were discussed from the aspects of adopting new adsorbent and new process of single adsorption tower, replacing PDEB with light desorption agent, optimizing operation parameters of adsorption tower and heating furnace, and selecting high efficiency and energy saving equipment. It is recognized that the closely cooperation of design and unit operation is helpful to reduce the energy consumption of the units. The design needs in mind for the possible problems in the process scheme and equipment and optimization to reduce energy consumption as much as possible. It is equally important that standardized production department, fined management and optimized daily operation, so as to further reduce the operation energy consumption of the device.

INFLUENCE OF SCHEMES FOR STEAM DRIVING COMPRESSORS ON ENERGY CONSUMPTION OF AROMATICS COMPLEX UNIT

Zhang Shuguang Liu Chengjun Liu Quanrun

2020, 51(2):  110-114. 

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The cycle hydrogen compressors of the toluene disproportionation and C8 aromatics isomerization processes (referred to as disproportionation and isomerization cycle hydrogen compressor) are the imperative equipments in the aromatics complex. Steam driving is a means to ensure the stable operation of compressor. The steams with different pressure levels can be used to drive the two kinds of compressors, but with different energy consumption. The schemes were compared to optimize the steam network of the aromatics complex, resulting in full use of the steam inside the aromatics complex and reducing the low pressure steam discharge, thus lowering the energy consumption of the whole aromatics complex. The evaluation results showed that the intermediate pressure steam of 1.8 MPa（IPS）of the aromatics complex can drive isomerization cycle hydrogen compressor and disproportionation cycle hydrogen compressor, and the energy consumption of the unit was the lowest, and the utility cost of paraxylene product was the lowest.