1、Designation: D 4463 96 (Reapproved 2006)Standard Guide forMetals Free Steam Deactivation of Fresh Fluid CrackingCatalysts1This standard is issued under the fixed designation D 4463; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers the deactivation of fresh fluid cata-lytic cracking (FCC) catalyst by hydrothermal treat
3、ment priorto the determination of the catalytic cracking activity in themicroactivity test (MAT).1.2 The hydrothermal treatment of fresh FCC catalyst, priorto the MAT, is important because the catalytic activity of thecatalyst in its fresh state is an inadequate measure of its truecommercial perform
4、ance. During operation in a commercialcracking unit, the catalyst is deactivated by thermal, hydrother-mal and chemical degradation. Therefore, to maintain catalyticactivity, fresh catalyst is added (semi) continuously to thecracking unit, to replace catalyst lost through the stack or bywithdrawal,
5、or both. Under steady state conditions, the catalystinventory of the unit is called equilibrium catalyst. Thiscatalyst has an activity level substantially below that of freshcatalyst. Therefore, artificially deactivating a fresh catalystprior to determination of its cracking activity should providem
6、ore meaningful catalyst performance data.1.3 Due to the large variations in properties among freshFCC catalyst types as well as between commercial crackingunit designs or operating conditions, or both, no single set ofsteam deactivation conditions is adequate to artificially simu-late the equilibriu
7、m catalyst for all purposes.1.3.1 In addition, there are many other factors that willinfluence the properties and performance of the equilibriumcatalyst. These include, but are not limited to: deposition ofheavy metals such as Ni, V, Cu; deposition of light metals suchas Na; contamination from attri
8、ted refractory linings of vesselwalls. Furthermore, commercially derived equilibrium catalystrepresents a distribution of catalysts of different ages (fromfresh to 300 days). Despite these apparent problems, it ispossible to obtain reasonably close agreement between theperformances of steam deactiva
9、ted and equilibrium catalysts. Itis also recognized that it is possible to steam deactivate acatalyst so that its properties and performance poorly representthe equilibrium. It is therefore recommended that when assess-ing the performance of different catalyst types, a commonsteaming condition be us
10、ed. Catalyst deactivation by metalsdeposition is not addressed in this guide.1.4 This guide offers two approaches to steam deactivatefresh catalysts. The first part provides specific sets of condi-tions (time, temperature and steam pressure) that can be usedas general pre-treatments prior to compari
11、son of fresh FCCcatalyst MAT activities (Test Method D 3907) or activities plusselectivities (Test Method D 5154).1.4.1 The second part provides guidance on how to pretreatcatalysts to simulate their deactivation in a specific FCCU andsuggests catalyst properties which can be used to judgeadequacy o
12、f the simulation. This technique is especially usefulwhen examining how different types of catalyst may perform ina specific FCCU, provided no other changes (catalyst additionrate, regenerator temperature, contaminant metals levels, etc.)occur. This approach covers catalyst physical properties thatc
13、an be used as monitors to indicate the closeness to equilibriumcatalyst properties.1.5 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety concerns, if any, associated
14、with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 3663 Test Method for Surface Area of Catalysts andCatalyst Car
15、riersD 3907 Test Method for Testing Fluid Catalytic Cracking(FCC) Catalysts by Microactivity TestD 3942 Test Method for Determination of the Unit CellDimension of a Faujasite-Type ZeoliteD 4365 Test Method for Determining Micropore Volume1This guide is under the jurisdiction of ASTM Committee D32 on
16、 Catalysts andis the direct responsibility of Subcommittee D32.04 on Catalytic Properties.Current edition approved Oct. 1, 2006. Published November 2006. Originallyapproved in 1985. Last previous edition approved in 2001 as D 446396(2001).2For referenced ASTM standards, visit the ASTM website, www.a
17、stm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.and Zeo
18、lite Area of a CatalystD 5154 Test Method for Determining Activity and Selectiv-ity of Fluid Catalytic Cracking (FCC) Catalysts by Micro-activity TestE 105 Practice for Probability Sampling Of MaterialsE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 456 Terminology Relati
19、ng to Quality and StatisticsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Summary of Guide3.1 A sample of fresh fluid cracking catalyst is placed in areactor, either fixed bed or preferably fluid bed, and iscontacted with steam at elevated temper
20、ature. This treatmentcauses partial deactivation of the catalyst.NOTE 1In a fixed bed reactor, material containing sulfates, chlorides,etc. can result in significant additional chemical deactivation.3.2 The catalyst is withdrawn from the reactor and may besubjected to an activity or activity plus se
21、lectivity determina-tion, by using the microactivity test (Test Methods D 3907 orD 5154).4. Significance and Use4.1 In general, steam treatment of FCC catalyst can be usedeither to compare a series of cracking catalysts at a simulatedequilibrium condition or conditions, or to simulate the equilib-ri
22、um condition of a specific cracking unit and a specificcatalyst. This guide gives an example for the first purpose andan approach for the latter purpose.5. Apparatus5.1 Fixed bed or fluid bed steaming reactors can be used forthe hydrothermal treatment of FCC catalyst.5.2 In the steaming reactor, tem
23、peratures of the catalyst canbe maintained at selected constant mean levels between 700C(1292F) and 850C (1562F) 6 2C (6 3.6F) during thesteam treatment.5.3 Temperature control during steam treatment is critical,as temperature variations of 62C (63.6F) can lead to 61wt. % conversion changes or more,
24、 especially at higher tem-peratures.5.4 In fixed bed steaming, the temperature gradient throughthe catalyst bed should be kept as small as possible and shouldnot exceed 4C (7.2F). In fluid bed steaming the bed tempera-ture must be homogeneous.5.5 Heating and cooling of the catalyst must be performed
25、in the reactor under a flow of dry nitrogen.5.6 Precautions must be taken to achieve uniform contact ofthe steam with the bed.6. Sampling6.1 A suitable sampling procedure is needed. Practice E 105is appropriate.7. Sample Preparation7.1 No sample preparation is necessary if the catalyst isheated slow
26、ly during preheating (non-shock steaming).7.2 If the sample is introduced directly into a preheatedsteaming reactor, (shock-steaming) it is desirable to predry thesample for about one hour at about 550C (1022F) to preventexcessive catalyst loss.8. Procedure8.1 Procedure for fluid bed and fixed bed s
27、team treatment(non-shock steaming):8.1.1 With the reactor heated to 300C (572F) or lower,load the reactor with catalyst.8.1.2 Start nitrogen flow to the reactor at a flow velocity of3 cm/s (0.1 ft/s).8.1.3 Heat the reactor at the maximum rate until a tempera-ture of 600C (1112F) is reached.8.1.4 Kee
28、p the temperature constant at 600C (1112F) for30 min in order to remove volatile material from the catalyst.8.1.5 Heat the reactor at the maximum rate until the desiredsteaming temperature is reached; for example, at 760, 788 or800C (1400, 1450 or 1472F) 6 2C (6 3.6F).8.1.6 Stop the nitrogen flow an
29、d start a flow of undilutedsteam at atmospheric pressure and at constant temperature(760, 788 or 800C). Continue this steam flow for 5 hours. Forfixed bed operation, keep the steam flow velocity at 5 6 1 cm/s(0.16 6 0.03 ft/s) at the desired deactivation temperature. Forfluid bed operation, keep the
30、 steam velocity at 3 6 1 cm/s (0.106 0.03 ft/s).8.1.7 After 5 h, stop the steam flow and start nitrogenflowing at 3 cm/s (0.10 ft/s) through the reactor.8.1.8 Cool down the reactor to less than 300C (572F). Therate of cooling is not critical.8.1.9 Remove the catalyst from the reactor and store in as
31、ealed bottle.8.2 Variations in this procedure in which predried catalyst isadded to a steaming reactor preheated to the desired steamingtemperature (shock steaming) are also permissible provided aconsistent procedure is used.8.3 Testing of Steamed CatalystThe steamed catalyst maybe tested for gas oi
32、l cracking activity or activity plus selectiv-ity, using Test Methods D 3907 or D 5154, respectively.9. Precision and Bias39.1 Test ProgramAn interlaboratory study was conductedin which the wt % MAT Conversion was measured in two testmaterials steamed at three temperatures each in fixed or fluidbed
33、steaming reactors in ten separate laboratories. Multiplesample portions were steamed only by some laboratories, andnot all temperatures were used by all the laboratories. PracticeE 691 was followed to the extent practicable for the data set.Analysis details are in the research report.9.2 PrecisionPa
34、irs of test results obtained by a proceduresimilar to that described in the study are expected to differ inrelative value by less than 2.772*S, where 2.772*S is the 95 %probability interval limit on the difference between two testresults, and S is the appropriate estimate of relative standard3Suppor
35、ting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D32-1012.D 4463 96 (2006)2deviation. Definitions and usage are given in TerminologyE 456 and Practice E 177, respectively.Mean Within-LabRelative StandardDeviation in Wt. %MAT Conversion9
36、5 % RepeatabilityInterval (WithinLaboratory)S = 2.6 % 7.2 %Mean Between-LabRelative StandardDeviation in Wt. %MAT Conversion95 % ReproducibilityInterval (BetweenLaboratories)S=4.8% 13.3%The within-lab repeatability is of the same order as thatfound for the wt. % MAT conversion itself.9.3 BiasThis pr
37、ocedure is without known bias, since thereis by definition no absolute standard for comparison.10. Approach to Simulate a Certain EquilibriumCatalyst10.1 It is frequently desirable to find steaming conditionswhich give as close a match as possible to the properties of anequilibrium catalyst from a p
38、articular FCC unit. These condi-tions can then be used with other catalysts to be evaluated forthat unit with some assurance that the steaming conditions areappropriate to simulate the severity of that particular catalystaddition rate and the regenerator severity. Due to differences inhydrothermal s
39、tability of various zeolite and matrix compo-nents currently in use in FCC catalysts, a perfect match cannotbe obtained with all catalysts under the same steaming condi-tions.10.2 Critical steamed catalyst properties to be matched tothe equilibrium catalyst include MAT conversion (activity) andselec
40、tivity to products such as coke, hydrogen and C1to C3hydrocarbons which are sensitive to the relative activities ofthe zeolite and matrix components of contemporary crackingcatalysts.4Also the ratio of isobutane/(C3olefins + C4olefins)can be used as an indicator for the ratio of zeolite cracking/mat
41、rix cracking. Another critical parameter is the zeolite unitcell size which is, for many catalysts, related to gasoline octanequality. Physical measurements which have been found to beparticularly useful in evaluating the match between steamedand equilibrium catalysts are total, matrix (mesopore) an
42、d (bydifference) zeolite (micropore) surface areas as defined by TestMethods D 3663 and D 4365 and zeolite unit cell size of thezeolite from Test Method D 3942.10.3 A major problem in steaming fresh catalysts to matchequilibrium catalyst is that the zeolite and matrix componentsdeactivate at differe
43、nt rates relative to each other underaccelerated hydrothermal conditions than they do at the lowertemperatures and steam partial pressures in the FCC unitregenerator.5This rate difference is most pronounced with highmatrix activity catalysts having hydrothermally stable matricesand results in steame
44、d catalysts having excessive matrixactivity at the same overall activity as the equilibrium catalyst.Relatively higher matrix activity shows up as higher coke,hydrogen and light hydrocarbon yields in the MAT relative tothe equilibrium catalyst and as a higher matrix (mesopore)surface area. This prob
45、lem can be alleviated somewhat byusing longer steaming times at lower temperature, but cannotbe eliminated by any practical experimental conditions.10.4 Steaming conditions which have proven to be usefuland practical for simulating various FCC units are times of 4 to6 h at temperatures from about 78
46、0C (1436F) to 810C(1490F). Alternatively, longer times of 16 to 24 h at about25C (45F) lower temperatures may be used. Another tech-nique to simulate equilibrium catalyst properties is to mixportions of catalyst, each steamed under different conditions oftime, temperature and steam partial pressure,
47、 in order to bettermatch the presence of different catalyst ages in an actualequilibrium catalyst.6Also mixtures of fresh and uniformlysteamed catalyst portions can simulate the selectivity proper-ties of equilibrium catalysts.7ASTM International takes no position respecting the validity of any pate
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