Development of a Novel Type Catalyst SY-2 for Two-Stage Hydrogenation of Pyrolysis Gasoline

Advancesin Refining TechnologyDevelopment of a Novel Type Catalyst SY-2 forTwo-Stage Hydrogenation of Pyrolysis GasolineWu Linmei;Zhang Xuejun; Zhang Zhihua; Wang Fucun(Research Institute of Daqing Petrochemical Company, Daqing 163714) .Abstract: By using the group IIB or groupVIIB metals and modulating the characteristics of electric chargeson carrier surface, improving the catalyst preparation process and techniques for loading the active metalcomponents, a novel type S Y-2 catalyst earmarked for two-stage hydrogenation of pyrolysis gasoline hasbeen developed. The catalyst evaluation results have indicated that the novel catalyst is characterized by abetter hydrogenation reaction activity to give higher aromatic yield.Key words: pyrolysis gasoline; catalyst; hydrogenation1 Introductionprise theorganic impurties while saturating the mono-olefins,which can serve as potential aromatic feedstock for produc-Pyrolysis gasoline is an important by -product of ethylene ing benzene, toluene and xylenes.industry, with its yield accounting for 30 percent to 50 per-cent of ethylene production capacity. Pyrolysis gasoline con- Recently the development of pyrolysis gasoline hydrogena-tains more aromatic hydrocarbons, so it is one of the main tion catalysts, in particular the catalysts for two-stage hydro-feedstocks for making aromatic hydrocatbons. However, be- genation of pyrolysis gasoline, is very active. The domesticcause pyrolysis gasoline contains more unsaturated hydro- research institutions have developed a host of catalysts forcarbons and sulfur, nitrogen and oxygen containing two stage hydrogenation of pyrolysis gasoline and accom-compounds, the pyrolysis gasoline quality is unstable. In plished commercial applicationof these catalysts(- 41. On theorder to use pyrolysis gasoline as the feedstock for produc- basis of research on catalysts for two-stage hydrogen ationing aromatic hydrocarbons, the impurities contained in gaso- of pyrolysis gasoline, the Research Institute of Daqing Pet-line must be removed through hydrogenation reaction.rochemical Company carried out tests on pyrolysis gasolinehydrogenation unit at Daqing Petrochemical Company, whileGenerally hydrogenation of pyrolysis gasoline is a two-stage studying the reaction mechanism of two-stage hydrogena-hydrogenation process applied in commercial scale. Attion of pyrolysis gasoline on domestic catalysts, analy zingpresent, the domestic technology for hydrogenation of py- the characteristics of catalysts for two-stage hydrogenationrolysis gasoline is divided into fourkinds ofprocesses, namely of pyrolysis gasoline, and working on methods for improvingtheGerman HOUDRY technology, the French IFP technology, the carrier properties, resulting in successful development ofthe American S&W technology, and the American LUMMUS a novel catalyst SY-2 for two-stage hydrogenation of pyroly-technology , respectivelyl"l. The first-stage hydrogenation sis gasoline with a better reaction activity and a higher aro-mainly adopts the noble metal Pd based-catalyst, which dur- matics yield.ing the first-stage low-temperature liquid-phase hydrogena-tion reactions can remove the highly unsaturated conjugated 2 Design of Catalystalkenes, conjugated cyclic alkenes and styrene, etc. The sec-ond-stage hydrogenation reactions are conducted on Co- 2.1 Reaction mechanismMo-Ni-Y-A,O, catalysts, which under the high- temperature,gas-phase hydrogenation reaction conditions can reduce the The two-stage hydrogenation reactions of byrolysis gaso-sulfur, nitrogen, and oxy gen containing compounds that com- line involve firs中国煤化工no-olefins andfYHCNMHG29.China Petroleum Processing and Petrochemical TechnologyNo.3, September 2004hy drod esu lfurization reactions, and secondly the h ydro- nation of transition metals Co-Mo-Ni or Co-Mo as the activedenitrogenation and hydro-deoxidization reactions. Themain components supported on Y-Al2O3 as the carrier. The poretypes of reactions are as followsl5-9):structure characteristics of catalysts are as follows: Its porevolume is about 0.40 ml/g, its specific surface area is 220-①Alkene hydrogenation reaction: The chain alkenes, cyclic 230 m2/g and its bulk density is 0.75g/cm with an averagealkenes and diolefins are con verted into corresponding al- pore radius of about 40A.kanes after hydrogenation.2.3 Development of a novel catalyst SY-2 for②Hydrodesulfurization reaction: If the feedstock contains two-stage hydrogenation of pyrolysis gasolinemercaptans, thioether, alkyl disulfides, cyclic sulphides andthiophene, they can be converted into corresponding alkanes The surface nature of catalyst, its narrow channel structureand hydrogen sulfide gas through hydrodesulfurization and dispersion of metal components on the carrier can deter-reaction.mine the reaction performance of catalyst. If the catalyst fortwo-stage hydrogenation of pyrolysis gasoline uses Co-Mo-❸Deoxidization reaction: Oxides in the feedstock are mainlyNi or Co-Mo metals as the active components supported onphenols and peroxides, which can be converted into corre- Y Al,O3 as the carrier, in order to obtain y-Al,Ocarrier withasponding alkanes and water through hydrogenation reaction.high dispersion rate, elements such as Ti,Zr, Li, K or Mg canbe used to modify the property of γAl,O, crrel3+(l. In④Denitrogenation reaction: Nitrogen compounds in the feed-order to have a larger pore volume, a larger specific surfacestock are mainly composed of aniline, pyridine and quinoline. area and centralized pore size distribution on carrier, the Si,The denitrogenation rate is less when the pressure is much Zn, or P based pore expanding agents and improved Al,O3lower. Nitrogen compounds can be converted into corre- preparation methods are adopted to make carrier with ansponding alkanes and ammonia through hy drogenation ideal specific surface area and pore structure 17-211.Through studying the reaction mechanism of catalysts forFeedstock to the pyrolysis gasoline: Hydrogenation unit at two-stage hydrogenation of pyrolysis gasoline, analyzing theDaqing Petrochemical Company is composed of the pyroly- characteristics of two-stage hydrogenation catalysts and re-sis gasoline fractions ofC; E。The hydrogenation process search on methods for carrier modification and preparation,is aimed at providing feedstock for production of aromatic the Research Institute of Daqing Petrochemical Company hashydrocarbons. Therefore the catalyst design must conform developed a novel catalyst for two-stage hydrogenation ofto the main target of hydrogenation reaction, while control-pyrolysis gasoline, innov ations of which were realizedling over side reactions of benzene hydrogenation to in- through:crease the aromatic hydrocarbon yield.(1) Using the group IIBW or group VIB metals to adjust thesurface charge characteristics of carrier, restrain and reduce2.2 Catalyst propertythe carbon deposition on cataly sts during the hydrogena-tion reaction;The catalysts for hydrogenation of pyrolysis gasoline aremainly composed of Co-Mo-Ni type metal catalysts. The (2) Adjusting the catalysts preparation process to providephysico-chemical properties of advanced domestic and over- the catalyst carrier with a regular narrow channel structureseas catalysts for two-stage hydrogenation of pyrolysis gaso-suited to carry ing out pyroly sis gasoline hydrog enationline are shown in Table 12 -.10 +21.reaction;It can be seen from Table 1 that the two-stage hydrogenation (3) Improving the technique for loading the active metal com-catalysts are composed of a bi-metallic or tri-metallic combi- ponents in order中国煤化工ts dstributionYHCNMHG30.Advancesin Refining TechnologyTable 1 Physico-chemical properties of domestic and overseas catalysts for two-stagehydrogenation of pyrolysis gasolineItemCat-1Cat-2Cat-3Cat-4Cat-5| Physical properties:Pore volume, mLg0.490.380.46Specific surface area, m/g220230248Average pore radius, A4432403439Bulk density, g/mL0.740.780.730.720.7- 0.8ShapeSphereCylindrical extrudateTrilobeExtrudate| Chemical compositions, m%MoO313.413315.213.5Ni52.72CoO31.683.98Al,O3Balanceand reduce metal conglomeration. The new generation novel catalyst revealed a better hydrogenation reaction activity andcatalyst for two-stage hydrogenation of pyrolysis gasoline，a higher aromatic hydrocarbon yield. However, the catalystsdesignated as SY-2, is prepared by the impregnation method. samplesCat-1- Eat-5 could not meet the requirements of com-The phy sico -chemical properties and composition of the mercial pyrolysis gasoline hydrogenation unit and the aro-SY-2 catalyst are presented in Table 2.Table 2 Physico-chemical properties and3 Catalyst Evaluation Resultscompositions ofthe SY-2 catalystCatalystSY-2Catalyst evaluation was conducted in two 100mL laboratory| Physical propertieshydrogenation test units. The cataly sts assessed includedPore volume, ml/g0.45the SY-2 catalyst along with the domestic and overseas ad-202vanced cataly sts earmarked for two-stage hydrogenation of4pyrolysis gasoline. According to the instructions for use ofcatalyst in commercial unit, the following condition wereadopted for catalyst testing: a hydrogen partial pressure of| Chemical composition, m%4.2 MPa, a LHSV of 4.0h", and a hydrogen/oil(volume) ratioMoO-NiO17- 19Co-catalystof 300:1. The same feedstock was used for testing all catalysts.Catalyst evaluation tests required that the hydrogenateY-Al,O3should have a bromine number of less than 0.5g Br/(100g of matic hydrocarbon loss could reach up to 3%. The outcomeoil), and adiene value of less than 0.1g I/(100g ofoil). Com- of evaluation tests indicates to the sheer success in develop-parison of catalysts evaluation results is shown in Table3. ment of the novel SY-2 catalyst used for two-stage hydroge-nation of pyrolysis gasoline.Table 3 indicates that under the following conditions, i.e.: areaction temperature of 250C, a hydrogen partial pressureof 4 Conclusions4.2 MPa,a LHSV of 4.0h*, and a hydrogen/oil(volume) ratioof 300:1, the hydrogenate had a bromine number of 0.49g (1) By using the group IBI or group VIBI metals to adjust theBr/(100g of oi), adiene value of 0 and an aromatic hydrocar- carrier surface charge characteristics, improve the catalystbon loss of 2.1 9%, which could meet the requirements of preparation process and techniques for loading of activecommercial pyrolysis gasoline hydrogenation unit and the metal componer中国煤化工st for two-stageYHCNMHG31.China Petroleum Processing and Petrochemical TechnologyNo.3, September 2004Table 3 Comparison of catalysts evaluation resultsBromine value,Diene value,AromaticsAromatic hydrocarbonItemgBr/( l00goil)gI,/(100goil)content, %loss, %| Reaction temperature: 230 CCat-12.840.0583.782.08Cat-26.6984.121.68Cat-35.870.1083.642.24Cat-46.960.0184.171.62Cat-54.3383.921.92SY-22.010.0684.451.30| Reaction temperature: 240 C1.720.0383.152.823.580.0783.632.3883.015.260.0083.582.312.9383.412.511.1084.09| Reaction temperature: 250 C0.5482.493.593.1282.913.101.4383.032.963.2483.161.4182.453.630.4983.692.19Note: The feedstock property is as follows: bromine Nois 33.4 gBr,/100g of oil, diene value is 2.1 gI/100g of oil, aromatichydrocarbon content is 85.56%.hydrogenation of pyrolysis gasoline has been developed.[2]Ren Rongkang. Development of HydrodesulfurizationCatalyst1 forPyrolysisGasoline. PetroleumProcessing[J], 1992,(2) The catalyst evaluation results had indicated that under (5), 42- 47the following operation conditions, ie: a reaction tempera- [3]Zhang Kongyuan. Development of the LH-02ture of 250C, ahydrogen pressure of 4.2 MPa, aLHSV of4.0 Hydrodesulfurization Catalyst. QILU Petrochemicalh', a hydrogen/oil (volume) ratio of 300: 1, the hydrogenate Technologyl,1999,25(1),19 22obtained during hydrogenation of pyrolysis gasoline on the [4]Meng Xiangbin. Development of New Generation Cata-SY-2 catalyst had a bromine number of0.49g Br,/( 100gofoil)，lyst for Two Stage Hydrogenation of Pyrolysis Gasoline. In-and a diene value of 0, which could meet the product quality dustrial Catalysis[J],2003,11(5),16- 48control target for commercial hydrogenation unit, and the [5]Wen Huixin. Reaction Kinetics Applicable to the Petro-catalyst showed a higher hydrogen reaction activity coupled leum Refining Processes [M]. Bejjing: The Hydrocarbon Pro-with a higher aromatic hydrocarbon yield.cessing Publishing House, 1985- 303[6]Hu Sheng. Development and Application of a Novel TypeReferencesCatalyst for Pyrolysis Gasoline Hydrogenation. Helongjang[1]Wang Zizong. Development of Pyrolysis Gasoline Hydro-Petrochemicals[J,2001(1):1-3genation Process and Reactor. Petrochemical Design[J],2002，[7]Zhao Ye. Development and Application of the Pyrolysis .19(1),1-9Gasoline Hydrofil中国煤化IetrochemicalsYHCNMHG32.Advancesin Refining Technology[J],1995(4):25- 28[14] Yang Xiyao. Hydrodesulfurization Catalyst for Hydro-[8]Zeng Yi. Report on Evaluation of Catalysts for Pyrolysis catbonsIP].CN1015902B.1992-03-18Giasoline Hydrogenation. Hydrogenation Technology[J]，[15] RamirieZJorge et.al; Appl. Catal .52(3),211- 213, 1989.1999,25(4):34- 45[16] Marvin F.1Johnson, J. Catal, 123(1), 245- 259, 1990.[9] Han Congren. Hydrocracking Process and Engineering. [17] Zhang Kongyuan, Catalysts for Hydrodesulfurizationof[M]. Bejjing: China Petrochemical Publishing House, 2001 ( Hydrocarbons and Their Preparation. [P],CN1 1233 10A, 1996-7):31- 755-29.[10] Study on High Space Velocity Two Stage Catalytichy- [18] Monica E. Choca. Phosphoro- Alumina Gel and Methoddrogenation of Pyrolysis Gasoline. [M]. Research Instituteof ofPreparation. [P].US: 4066572,1978-01 -03DaqingPetrochemical Company,1996,11[19]Zhang Tingqin. Development ofa Co-Mo-Ni/A1,O,Cata-[11] Collection of Materials on Comparison of Domestic and lyst for PyrolysisGasoline Hydrogenation. Industial CatalysisOverseas Catalysts Performance. [M]. Development Depart- [J,2000(5): 45- 47ment of China Petrochemical Corporation,1988,7- 43[20] Harry E. Robson. Preparation of Catalysts of Predeter-[12] Appraisal Material Regarding theLY-9302 Catalyst Used mined Poresize Distributionand Pore Volume.[P]US:4016108,in Hydrofining Technology.[M]. China Petrochemical Cor-1997-0405poration Lanzhou Chemical Research Instute, 1993,11[21]Du Mingxian. Preparation of Alumina with High Specific[13]Zhao Ye, et al. Preparation ofa Hydrogenation Catalyst Surface Area and Narrow Pore Size Distribution. Chinese Jour-[PI.CN1353168A.2002-06-12nal ofCatalysis[J], 2002(5): 465- 468.Cold Box for the 660 Kt/a Revamp Proj ectat BYPC Passed Apprai salThe large ethylene cold box designed for the 660 kt/arevamp for investig ation and domestic manufacture of cold box.project at Beijing Yanshan Petrochemical Company (BYPC)Hangzhou Oxygen Compressor Works after several years ofand fabricated by the Hangzhou Oxygen Compressor Works,，research and development work had succesfully manufac-Ltd. has passed the national appraisal. It is learned that all tured a large cold box for the 660 kt/a ethylene expansionindicators of this equipment has been reached the contempo- project, and had exported tens of critical parts of cold box torary intrnational level of similar equipment and has flled the the US and Canada.gap in the manufacture of cold box for China' s ethyleneindustry.The cold box for the 660 kt/a ethylene expansion project atBYPC was istalledl in 2001 and has been running excellentlyThe cold box is the key equipment of ethylene production till now with good adaptability to work conditions. It canunit, and China has been dependent on cold box imports for fully meet the requirements of ethylene production and hasa long time. Before 1999 the R&D and fabrication of a com- enhanced the output and improved the quality of ethyleneplete set of cold box was not carried out in China with the product, bringing about obvious economic effect to BYPC.exception of some spare parts of the cold box manufactured The successful operation of this cold box, the largest andby Hangzhou Oxygen Compressor Works. During the“Ninth most complicated one insideChina, has implemented the goalFive-Year Plan”period, China had included the domesticfor domestic manufacture of large cold box, which has sym-manufacture of cold box for ethylene unit into the list ofkey bolized China' s capability in design and fabrication of coldproblems for manufacture of major technical equipment, and box and its ability to provide the said equipment.designated Hangzhou Oxygen Compressor Works as the base中国煤化工MHCNMH G33.