Table of Content

12 July 2013, Volume 44 Issue 7

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STUDY ON REACTION CHARACTERISTICS AND INFLUENCE FACTORS OF NAPHTHA CATALYTIC CRACKING

2013, 44(7):  1-6. 

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Based on the analysis on composition characteristics，diffusion and adsorption performance of naphtha over zeolite catalysts, the experiments of naphtha cracking over zeolite catalysts were conducted in a laboratory fixed fluidized bed reactor. The influence of reaction temperature, residence time and microactivity of catalysts on product slate was explored. The results indicate that naphtha, which is rich in small saturated hydrocarbons, shows less pore diffusion limitation, weak adsorption ability in the typical zeolite catalysts, and high reaction activation energy in catalytic cracking. Thus, several conceptions that naphtha catalytic cracking reaction could be promoted effectively by developing hierarchical porous structure zeolites, improving adsorption performance of small saturated hydrocarbons and adopting high severity reaction conditions are proposed.

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APPLICATION OF ALKYL POLYAROMATIC RATIOS AS HYDROCARBON FINGERPRINT IN FCC PROCESS

2013, 44(7):  7-11. 

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1-methylnaphthalene/amylbenzene and tetralin were cracked in micro-pulse reactor，respectively and the contents of alkylnaphthalenes in products were determined using GC-MS. It is found that the amount ofαandβposition isomers are increased with increase of reaction conversion and the variation of conversion can be reflected by the ratio of alkyl substituent naphthalenes at different position. Further results confirm that the naphthalene alkylation follows the same mechanism in different reaction systems and is affected by the pore structure of the catalyst used. Hydrocarbon fingerprint information was extracted from the reaction products of five different vacuum gas oils, and the results show that the fingerprint of alkylnaphthalene and alkylphenanthrene can both be used as indicators of cracking conversion.

STUDY ON INFLUENCING FACTORS ON PARTICLE SIZE AND STABILITY OF ASPHALT EMULSION AND THEIR CORRELATION

2013, 44(7):  12-16. 

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The influence of emulsifier, soap solution pH value, storage time, storage temperature on the particle size and stability of bitumen emulsion was investigated by means of laser particle size analysis and residue content difference tests. The correlation degree between stability/particle size and various factors was analyzed based on the gray relation theory, and the correlation between stability and particle size was also investigated. Results show that there are good correlations between the influencing factors with the particle size and stability of bitumen emulsion. When the dosage of emulsifier is increased, the particle size and storage stability are both reduced, creating more stable emulsions, then the trend tends to be stable at last. The particle size and storage stability are both increased as pH value of the system and storage temperature increases. The particle size and storage stability increases firstly and then comes to a plateau with storage time increasing. The gray correlation analysis shows that the correlation between the stability and various influencing factors descends in the order: pH value>storage temperature>emulsifier>asphalt type>storage time， while the correlation between the particle size and various factors decreases in the order: pH value>the storage temperature>emulsifier>storage time>asphalt types.

DEEP DESULFERIZATION OF HYDROGASOLINE BY ADSORPTION IN H2 ATMOSPHERE OVER Ni/ZnO-SiO2-Al2O3

2013, 44(7):  17-21. 

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Ni/ZnO-SiO2-Al2O3 adsorbents were prepared by impregnation and wet mixing methods，respectively. XRD and mercury porosimeter were adopted to characterize the crystal structure of the adsorbent s. A fixed bed reactor was used to investigate the desulfurization performance of hydrogasoline with different adsorbents. The results show that the adsorbents prepared by wet mixing method have a higher special surface area and similar pore volume and better desulfurization performance compared with the adsorbents prepared by impregnation method. The desulfurization experiment using the hydrogasoline from Shandong Hengyuan petrochemical company as feed indicates that the content of sulfur is decreased from 69 μg/g to 10μg/g, while the octane number of the gasoline produced decreases by only 0.6 and the sulfur capacity of the adsorbent is up to 9.98 wt% at the conditions of 350 ℃, 2.0 MPa, LHSV of 7.0 h-1, hydrogen to gasoline volume ratio of 60:1. The adsorbent has a good adaptability to various hydrogasolines. The desulfurization performance of the adsorbent regenerated for 3 times is the same as that of the fresh one.

CHARACTERIZATION OF BASIC NITROGEN COMPOUNDS IN COKER GAS OIL BY ESI FT-ICR MS AND THEIR CATALYTIC CRACKING PERFORMANCE

2013, 44(7):  22-27. 

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The basic nitrogen compounds were extracted by hydrochloric acid and alcohol from CGO. Then the types and structures of basic nitrogen species in CGO and its hydrochloric extract were characterized by Electrospray Ionization (ESI) Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS), and the catalytic cracking performance of the basic nitrogen compounds was studied. The data indicate that N1 type basic nitrogen compounds are dominant in CGO and these species are mainly derivatives of quinoline and benzoquinoline with alkyl and cycloalkyl chains. Under the conditions of FCC, the basic nitrogen compounds extracted from CGO still have certain catalytic cracking ability; however, the conversion is relatively low. The bond-breakages of alkyl side-chains, cycloalkyl side-chains and biphenyl bridge are the main reaction. High content of basic nitrogen compounds and polycyclic aromatic hydrocarbons are the key factors that lead to lower conversion and poorer products distribution.

STUDY ON COKING TENDENCY OF FEEDSTOCK IN VACUUM FURNACE OF ATMOSPHERIC-VACUUM DISTILLATION UNIT

2013, 44(7):  28-32. 

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Deep-cutting operation of vacuum distillation is limited by its investment and energy consumption and its coking tendency in vacuum furnace. In this paper, the coking tendencies of residue fractions（>565℃）were connected with their amount of toluene insoluble (TI), the precursor of coke, formed during heating. The effect of temperature and residence time in the furnace on the amounts of TI of heavy fractions was tested to get the critical curve of anti-coking for the fractions with different properties. It is discovered that high temperature and longer staying time in the furnace will aggravate the formation of TI and that the fractions from different base crudes have their own special critical curve of anti-coking. The test results indicate that the amount of TI can be used for judgment of coking tendency of the heavy fractions.

IMPACT OF CaO ON Cr2O3/Al2O3 CATALYST STRCTURE AND ISOBUTANE DEHYDROGENATION PERFORMANCE

2013, 44(7):  33-37. 

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To study the impact of alkali metal oxides on the performance of isobutane dehydrogenation by Cr system catalyst, the Cr2O3/Al2O3 and Cr2O3/Al2O3-CaO catalysts were prepared by incipient wetness impregnation. The performance was evaluated and BET, XRD, NH3-TPD were used to characterize the catalysts. As a conclusion, the active ingredient Cr2O3 plays an important role in the catalysis process of isobutane dehydrogenation. Alkalinity or acidity of the carrier has a great influence on the selectivity of isobutane dehydrogenation. The addition of CaO can modify the surface properties crystalline structure and surface acidity of catalyst in different extent and thus improve the selectivity of the target product as well. At the content of Cr2O3 and CaO are 20% and 5%, the conversion and the selectivity are 25.31% and 91.08%, respectively.

STUDY ON PERFORMANCE OF NEW C8 AROMATICS ISOMERIZATION CATALYST

2013, 44(7):  38-42. 

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This paper introduces the performance of a new C8 aromatics isomerization catalyst RIC-200 in laboratory and commercial unit, and compares with the results of SKI-400 catalyst under the industrial conditions. The results of the new catalyst indicate that the performance of RIC-200 under industrial operation conditions is in accordant with the results in laboratory test and better than SKI-400. The new catalyst possesses distinct characteristics，such as low deactivation rate,high ethylbenzene conversion and enhanced isomerization activity under even high pressure, low H2/HC, low hydrogen consumption, and stable C8 aromatics yield. The RIC-200 catalyst also demonstrates its excellent adaptability in varying industrial operation conditions.

DEVELOPMENT OF NEW GENERATION SINGLE-STAGE HYDROCRACKING CATALYST FC-34 WITH HIGH MIDDLE DISTILLATES SELECTIVITY

2013, 44(7):  43-47. 

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A new generation of single-stage hydrocracking catalyst FC-34 has been developed to meet the domestic requirement of more clean transportation fuel and high-quality chemical feedstock. This catalyst is composed of a modified Y elite and a type of nana-amorphous silica-alumina as the main cracking components of FC-34 catalyst. DURM (Dispersion and Uniform Reactive Manufacture), a new catalyst manufacture technique, was adopted to make the catalyst with all the active components uniformly dispersed. Through the comparison of pilot plant tests, FC-34 hydro cracking catalyst demonstrates its suitable cracking activity, good hydrogenation performance, high selectivity of middle distillates and strong ring-opening ability. The overall performance in activity and middle distillate selectivity of FC-34 has reached to that of FC-14 catalyst. In addition, the BMCI of the tail oil can be greatly improved and used as an ideal feed for steam cracking to produce ethylene.

ISOMERIZATION OF STRAIGHT RUN GASOLINE OVER NANOSIZED HZSM-5

2013, 44(7):  48-52. 

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This paper introduces the performance of nanosized HZSM-5 and micronsized HZSM-5 in straight-run gasoline isomerization in a fixed bed under reaction conditions. The characterization of two molecular sieves were conducted by XRD, NH3–TPD and BET analysis. It is found that the nanosized HZSM-5 is more suitable for catalytic isomerization of straight-run gasoline than micronsized HZSM-5. This is because nanosized HZSM-5 has more external acid sites which favor the cyclization of paraffin and riches in secondary pores allowing more coke deposition. At 320-360 ℃ and WHSV of 1 h-1, nanosized HZSM-5 shows the best catalytic performance. Nanosized HZSM-5 can be used as an efficient catalyst for straight-run gasoline isomerization.

INFLUENCE OF HCl PRETREATMENT ON MICROSTRUCTURE OF Pd/C PTA REFINING CATALYST

2013, 44(7):  53-58. 

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A commercial coconut activated carbon was firstly pretreated by HCl with different concentrations. Then the Pd/C catalyst used for purification of terephthalic acid was prepared using immersion method based on the pretreated carbon. By means of SEM, EDS, TEM, XRD and BET techniques, the impact of HCl pretreatment on microstructure and activity of the catalysts was investigated, and the relationship between HCl concentration and catalyst activity was explored. Test results show that the catalytic activity first increases and then decreases with the increase of HCl concentration and the maximum activity was obtained at the HCl concentration of 0.6mol/L. SEM and adsorption-desorption tests show that the pretreatment of HCl can increase the average pore diameter and the mesopore volume of activated carbon. The EDS result indicates that the content of Pd maintains nearly constant, while some O element and trace impurity of Si and Cl appear on the carbon surface after HCl pretreatment. The changes of the surface morphology of HCl pretreated active carbon are not found. Owing to the increase of pore diameter and mesopore volume, the effective surface area of carbon for loading Pd component is increased, which is beneficial to the dispersity of Pd, and to the catalytic activity of Pd/C catalyst.

PREPARATION OF TITANIA WASHCOATS ON CORDIERITE MONOLITH DENOX CATALYSTS

2013, 44(7):  59-63. 

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The titania washcoats on cordierite monolith deNOX catalyst were prepared by dipping cordierite ceramic honeycomb in titania slurry using alumina sol as binder. The influence of different additives on titania coating and pH on viscosity of titania slurry was investigated. The TiO2 washcoats were characterized by microscopic analysis of ultrasonic surging, BET, SEM and XRD. It is showed that the pH of the titania slurry can affect the viscosity of slurry with the perfect viscosity at pH 1.780 of the titania slurry. Either urea or methenamine can improve the properties of titiania washcoats. The maximum loading, high adhesive capacity of the coatings and specific surface area can be obtained when 3% urea or 0.1% methenamine was added.

DIFFERENTIATED DEVELOPMENT OF REFININF-CHEMICAL INTEGRATION BASE

2013, 44(7):  64-68. 

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Petrochemical industry is developing toward the refinery and chemical integration. Intensive development is the primary competitive advantages of a large refinery and chemical integrated base. It is featured by the capital value improvement and resource utilization efficiency enhancement. This paper studied the planning scheme of a large refinery and chemical integrated base comprehensively with two optimized proposals for phase Ⅱand phase Ⅲ separately, and a conclusion is that developing and extending petrochemical industry chain will be the right way to differentially develop the base，which will be beneficial to balance the relationship of intensive development and scale expansion.

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PROBLEMS IN S Zorb PROCESS AND COUNTERMEASURES

2013, 44(7):  69-72. 

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In the second running period, larger differential pressure of reactor filter and fouling of the raw heat exchanger occurred in S Zorb unit in Gaoqiao Corporation. These problems brought great impact to the stable running of the S Zorb unit. The investigation discovered that the problems were occurred because of fouling of the filter and the heat exchanger. It is suggested that several methods can temporary be used to mild the problems, but the best way to reduce the pressure drop of the filter is to replace the filter cartridge and use new blow ball valves. While the fouling problem of the heater exchanger can be solved by thorough cleaning of bundle-tube of the heat exchanger and controlling the quality of FCC naphtha feed from tanks. These measures ensure a long period and stable running of the S Zorb unit.

INDUSTRIAL APPLICATION OF 650 kt/a ETHYLBENZENE COMPLETE TECHNOLOGY

2013, 44(7):  73-77. 

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The industrial application of 650kt/a ethyl benzene complete technology developed by Research Institute of Petroleum Processing has been conducted on PO/SM plant in Ningbo ZRCC LYONDELL Chemical Company. The results show that both alkylation catalyst and transalkylation catalyst display its good activity and stability when the ratio of benzene to ethylene and benzene to diethylbenzene are 3.1 and 8.0, respectively. In alkylation reaction, the ethylene conversion is 100%, the average ethyl-benzene selectivity is 86%, and the average ethylation is high up to 99.5%. In transalkylation reaction, the average diethylbenzene conversion is 75% and the average ethyl-benzene selectivity reaches to 99.5%. The process flow and equipment design are both successful, and the consumption of energy and material are reduced. The quality of ethyl benzene can meet the requirement of PO / SM plant for a long-term stable running.

DISTRIBUTIONS OF SOLID CONTENT IN EXIT ZONE OF RISER-BED REACTOR IN ‘ZERO-BED’ OPERATING MODE

2013, 44(7):  78-83. 

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According to ‘zero-bed’ operation mode of riser-bed reactor used in commercial unit, a large-scale cold mode experiment device of riser-bed was established, by which the distributions of local solid content in the exit zone were studied in the ‘zero-bed’ operating mode. The results were compared with the one of riser-bed coupled operation mode. The experimental results show that, affected by the distributor, local solid content decreases first and then increases as the gas-solid flow approaches to the exit of the riser. The distributions of local solid content near the wall region have no similarity, while are similar in other region. The radial dissimilarity of solid content increases first and decreases later. Compared with the riser-bed coupled operation, in the ‘zero-bed’ operation mode, local solid content in the axial cross section close to exit is small in core region, but large in wall region. After the distance from exit increases to a certain value, the whole radial solid content is small in the ‘zero-bed’ operating mode.

EFFECT OF CIRCULATING COOLING WATER TREATMENT ON SERVICE LIFE OF HEAT EXCHANGER AND PRODUCTION EQUIPMENT

2013, 44(7):  84-87. 

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Enhancing the effect of circulating cooling water treatment plays an important role in prolonging the actual life of heat exchanger and the operation period of the equipment, reducing cost and increasing benefit of the corporation. The relationship of the circulating cooling water treatment effect with the actual life of heat exchanger and the operation period of the equipment was analyzed. The conclusion can be drawn that the actual service life of the heat exchanger and the operation period of the equipment depend on the effect of circulating cooling water treatment. The excellent effect can ensure the actual life more than 18 years for the heat exchanger though the design life is only 8 years and the operation period of the equipment can be as long as 79 months. So it leads to an enormous economic benefit.

REVAMPING OF A 500 kt/a RFCC UNIT FOR ENERGY CONSERVATION

2013, 44(7):  88-92. 

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A 500 kt/a RFCC unit was successfully revamped for energy conservation in CNOOC Zhongjie Petrochemical Co.in June, 2012. The technology overcame conventional contradiction between reaction temperature and catalyst/oil ratio, and has realized the idea of operating the FCC unit under low reaction temperature and large catalyst/oil ratio. The product quality and yield, energy consumption and flue gas emission are satisfied with the contract. An additional economic benefit of 62.1 million RMB is gained annually.

ANALYSIS AND COUNTERMEASURES FOR AMMONIUM SALT PLUG AND CORROSION IN DEBUTANIZER OF CATALYTIC REFORMER

2013, 44(7):  93-95. 

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The question that ammonium salt block-up and corrosion in trays and air cooler for the debutanization column of continuous catalytic reforming unit is analyzed, which occurs during the long-term operation of Zhenhai Refining & Chemical Company's continuous catalytic reforming unit. According to the water-soluble property of chlorination ammonium salt, in practical production we use the method water injection cleaning before air cooler for the debutanization column and during charge-in to avoid ammonium salt's deposition, and achieved good practical results, ensure long-term operation of the device.

SEPARATION AND CHARACTERIZATION OF VACUUM CUTS OF SAUDI MIDDLE CRUDE OIL

2013, 44(7):  96-101. 

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The 3rd and 4th vacuum cuts of Saudi Arabia Middle crude oil were separated into four components: paraffins, light aromatics-saturates, middle aromatics and heavy aromatics by the solvent separation techniques (dewaxing and/or solvent extraction). The main properties, hydrocarbon types and structural parameters of VGOs and their components were characterized by GC, GC-MS and NMR, and the separation efficiency of the solvent separation methods was studied. The results show that 24.4%~36.8% of alkanes in VGOs come into the paraffins obtained by solvent dewaxing, about 12 times that of cycloalkanes, the alkane content in the paraffins is 88.3%~95.2% and the carbon number of the paraffins is normally distributed. The aromatic contents in heavy aromatics and middle aromatics components obtained by solvent extraction were 85.4%~88.8% and 73.2%~78.5%, respectively. As the components become heavier, the CN, CP, RA, RN and atoms of S and N in average molecular formula increase, but CA decreases. The separation percentage of aromatics with three and more rings was 72.8%~75.5%, about 5~8 times that of alkanes and 4~5 times that of cycloalkanes. So the selectivity and efficiency are high for separating alkanes and aromatics by solvent separation.