1、Designation: D7206/D7206M 06 (Reapproved 2013)1Standard Guide forCyclic Deactivation of Fluid Catalytic Cracking (FCC)Catalysts with Metals1This standard is issued under the fixed designation D7206/D7206M; the number immediately following the designation indicates theyear of original adoption or, in
2、 the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorially changed 8.2.1.1 in March 2013.1. Scope1.1 This guide covers the deactivation o
3、f fluid catalyticcracking (FCC) catalyst in the laboratory as a precursor tosmall scale performance testing. FCC catalysts are deactivatedin the laboratory in order to simulate the aging that occursduring continuous use in a commercial fluid catalytic crackingunit (FCCU). Deactivation for purposes o
4、f this guide consti-tutes hydrothermal deactivation of the catalyst and metalpoisoning by nickel and vanadium. Hydrothermal treatment isused to simulate the physical changes that occur in the FCCcatalyst through repeated regeneration cycles. Hydrothermaltreatment (steaming) destabilizes the faujasit
5、e (zeolite Y),resulting in reduced crystallinity and surface area. Furtherdecomposition of the crystalline structure occurs in the pres-ence of vanadium, and to a lesser extent in the presence ofnickel. Vanadium is believed to form vanadic acid in ahydrothermal environment resulting in destruction o
6、f thezeolitic portion of the catalyst. Nickels principle effect is topoison the selectivity of the FCC catalyst. Hydrogen and cokeproduction is increased in the presence of nickel, due to thedehydrogenation activity of the metal. Vanadium also exhibitssignificant dehydrogenation activity, the degree
7、 of which canbe influenced by the oxidation and reduction conditions pre-vailing throughout the deactivation process. The simulation ofthe metal effects that one would see commercially is part of theobjective of deactivating catalysts in the laboratory.1.2 The two basic approaches to laboratory-scal
8、e simulationof commercial equilibrium catalysts described in this guide areas follows:1.2.1 Cyclic Propylene Steaming (CPS) Method, in whichthe catalyst is impregnated with the desired metals via anincipient wetness procedure (Mitchell method)2followed by aprescribed steam deactivation.1.2.2 Crack-o
9、n Methods, in which fresh catalyst is subjectedto a repetitive sequence of cracking (using a feed withenhanced metals concentrations), stripping, and regeneration inthe presence of steam. Two specific procedures are presentedhere, a procedure with alternating metal deposition and deac-tivation steps
10、 and a modified Two-Step procedure, whichincludes a cyclic deactivation process to target lower vanadiumdehydrogenation activity.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; theref
11、ore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard
12、 to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions:2.1.1 crack-ontechnique of depositing metals onto a cata-lyst through cracking of an FCC feed with enhanced metalcontent in a fluidized catalys
13、t bed that is at cracking tempera-ture.2.2 Acronyms:2.2.1 E-catequilibrium catalyst from commercial FCCU.2.2.2 FCCfluid catalytic cracking.2.2.3 FCCUfluid catalytic cracking unit.2.2.4 LGOlight gas oil, fluid at 40C, initial boiling point250C, sulfur content of 2 to 3 mass percent.3. Significance an
14、d Use3.1 This guide describes techniques of deactivation that canbe used to compare a series of cracking catalysts at equilibrium1This guide is under the jurisdiction of ASTM Committee D32 on Catalysts andis the direct responsibility of Subcommittee D32.04 on Catalytic Properties.Current edition app
15、roved March 1, 2013. Published March 2013. Last previousedition approved in 2012 as D7206/D7206M06(2012)e1. DOI: 10.1520/D7206_D7206M-06R13E01.2Mitchell, B. R., Industrial and Engineering Chemistry Product Research andDevelopment, 19, 1980, p. 209.Copyright ASTM International, 100 Barr Harbor Drive,
16、 PO Box C700, West Conshohocken, PA 19428-2959. United States1conditions or to simulate the equilibrium conditions of aspecific commercial unit and a specific catalyst.4. Reagents4.1 Feed, VGO.4.2 Feed, LGO.4.3 Hydrogen (H2), 42.8 % in nitrogen balance.4.4 Nickel naphthenate or nickel octoate soluti
17、on.4.5 Nitrogen (N2).4.6 Oxygen (O2), 40 % in nitrogen balance.4.7 Vanadium naphthenate solution.4.8 Cyclohexane.4.9 n-pentane.4.10 n-hexane.4.11 Water, demineralized.5. Hazards5.1 The operations described in this guide involve handlingheated objects, fragile glassware, and toxic organic nickel andv
18、anadium compounds.5.2 All work with organic metals precursor solutions andother organic solvents should be completed in suitable ventedfume hood.5.3 Appropriate personal protection equipment, includingchemical goggles, laboratory smock, and disposable glovesshould be worn.5.4 Waste organic metal sol
19、utions and organic solvents shallbe disposed of properly in suitable waste containers andaccording to regulations.5.5 Vented furnaces and hoods should be regularly moni-tored for proper ventilation before using.5.6 Evaporating dishes should be checked for cracks beforeuse.5.7 The muffle furnace used
20、 for the post-impregnationthermal treatment of the sample shall be appropriately andadequately ventilated. Catalyst load sizes should be selected toavoid overwhelming the ventilation capacity of the furnace andallowing fumes to escape into the laboratory.5.8 To avoid the potential hazard of explosio
21、n in the mufflefurnace, impregnated samples shall be completely dry ofpentane prior to beginning the thermal post-treatment.5.9 Material safety data sheets (MSDS) for all materialsused in the deactivation should be read and understood byoperators and should be kept continually available in thelabora
22、tory for review.6. CPS Method6.1 Summary of PracticeA fresh FCC catalyst is impreg-nated with nickel, or vanadium, or both. Nickel and vanadiumlevels are controlled by a predetermined concentration for thesample. The catalyst is wetted with a mixture of pentane andnickel, or vanadium naphthenate, or
23、 solutions of both and thenmixed to dryness. After drying, the sample is thermally treatedto remove residual naphthenates. The sample is then ready forhydrothermal treatment of analysis as desired.6.2 Procedure:6.2.1 Catalyst Pre-treatment Before ImpregnationFor amuffle furnace pre-treatment (standa
24、rd), place the sample in adish using a shallow bed (12 in. maximum). Calcine the samplefor1hat204C 400F, then3hat593C 1100F. Thesample is then removed and allowed to cool to room tempera-ture. Catalyst should be returned to a sealed container as soonas it is cool.6.2.2 Steam Deactivation Pre-treatme
25、ntTypical condi-tions included hydrothermal treatment for2hat816C1500F, 100 % steam, and 0 psi. The catalyst is charged to apipe reactor, fluidized in air, and then lowered over a 3-h periodinto a 816C 1500F sand bath furnace. Air flow is switchedoff and steam introduced for 2 h. The reactor is then
26、 removedfrom the furnace and allowed to cool to room temperatureunder a nitrogen purge.6.2.3 Preparation of Nickel and Vanadium MixtureThedesired nickel/vanadium levels are calculated for the quantityof sample to be impregnated. The mass of nickel or vanadiumnaphthenate used to obtain the desired le
27、vels on the catalystsample are determined as follows:N 5 T/S 3W (1)where:N = naphthenate (nickel or vanadium mass used to obtainthe desired metal level on the catalyst),T = target level (the desired mass percent of nickel orvanadium, or both, to be loaded on the catalyst),S = metal solution (the kno
28、wn mass percent of nickel orvanadium in the naphthenate solution), andW = mass of catalyst sample to be impregnated.6.2.4 Impregnation:6.2.4.1 Catalyst is poured into an evaporating dish. The dishshall be large enough to allow for a catalyst bed height of12 in.6.2.4.2 Slowly pour the dissolved metal
29、s solution into thedish with catalyst while mixing at the same time. Wash theresidual naphthenate from the glass beaker with pentane andadd the wash to the catalyst.6.2.4.3 Stir the sample with a spoonula until it is completelydry. The appearance of very small lumps in the catalyst afterdrying is no
30、rmal. Large lumps indicate improper drying andshall be avoided. This can be done by adding enough pentaneto moisten the catalyst then repeating the stirring process. Highlevels of vanadium naphthenate will cause the sample to appeargummy and is normal.6.2.4.4 High Levels of Vanadium NaphthenateWhen
31、animpregnation calls for more than 5000 ppm vanadium, theimpregnation should be done in two steps. Otherwise, thevolume of naphthenate will overwhelm the volume of catalystused, affecting the accuracy in reaching the target level. If over5000 ppm vanadium is required, divide the required volume ofva
32、nadium naphthenate in half, impregnate, post-treat, andimpregnate again by adding the second half followed by asecond post-treat. If nickel is also requested, this should bedivided and added to the catalyst along with the vanadium.D7206/D7206M 06 (2013)126.2.4.5 Antimony AdditionIf antimony is reque
33、sted, triph-enylantimony is added to the catalyst after the nickel andvanadium have been added and the post treatment has beencompleted. The impregnation procedure is the same as thenickel and vanadium impregnation except that cyclohexane isused instead of pentane.Antimony will not dissolve in penta
34、ne.6.2.5 Catalyst Post-treatment After ImpregnationAfter theimpregnated sample has dried, it is placed in a vented mufflefurnace and heat treated to remove the naphthenates and cokeformed. The dishes are placed in the furnace at room tempera-ture and the temperature is raised to 204C 400F and held a
35、ttemperature for 1 h. The sample is then calcined at 593C1100F for 3 h before being removed and allowed to cool toroom temperature.6.2.6 Steam DeactivationSeveral methods exist, each re-quiring specific conditions. An example of such a method isshown in Table 1.7. Crack-on Approach 1: Alternating Cr
36、acking andDeactivation Cycles7.1 Summary of Practice:7.1.1 The crack-on units consist of a fluid bed reactor witha fritted gas distributor on the bottom. Nitrogen, air, steam andother specialty gasses can be fed through the bottom. Oil canbe delivered either from the top or bottom of the reactordepe
37、nding on the method. Temperature is controlled by a threezone electric furnace. A disengaging section on the top of thereactor prevents catalyst loss during operation.7.1.2 The crack-on method involves depositing metals onthe catalyst at cracking temperature using a feed with enhancedmetals content.
38、 The catalyst is regenerated after each crackingcycle.7.1.3 In Crack-on Approach 1, the catalyst is subjected tosevere hydrothermal deactivation after each cracking andregeneration cycle. By this method, significant deactivation hastaken place by the time the metals addition is complete.7.2 Procedur
39、e:7.2.1 Preparation of the CatalystOptionally screen thecatalyst to remove coarse contaminants and fine particles thatwould be lost during fluidization.7.2.2 Prepare the Feed:7.2.2.1 Weigh out and transfer the appropriate amount ofLGO into the feed vessel. The minimum amount of LGO willequal the num
40、ber of cracking cycles times the amount fed percycle.7.2.2.2 Individually add the organic metal compounds. Themass of each metal added shall be calculated to give the desiredmetal loading on the catalyst. If using this technique to performan E-cat simulation, the metal target may have to be substan-
41、tially reduced by 25 to 50 % of the actual E-cat metal contentin order to simulate the deactivation effects discussed in thescope.7.2.2.3 Stir the LGO with a mechanical stirrer, and option-ally heat, to insure homogeneity of the mixture throughout theprocedure.7.2.3 Set up the Reactor System:7.2.3.1
42、 Load the catalyst into the fluidized bed reactor. Theamount of catalyst charged depends on the geometry of thereactor vessel.7.2.3.2 Attach all external control, input, exhaust and safetydevices.7.2.3.3 Fill the water reservoir to the appropriate startingpoint.7.2.3.4 Start the flow of 100 % nitrog
43、en gas through theLGO feed tube.7.2.3.5 Start the flow of 100 % nitrogen through the sieveplate.7.2.4 Metallation and Regeneration:7.2.4.1 Set the reactor temperature (500 to 530C).7.2.4.2 Inject xx grams of the LGO prepared in 7.2.2 (xx =total mass LGO / number of cycles). A good rule of thumbmight
44、 be to set LGO per cycle equivalent to 20 to 50 % of thecatalyst mass.7.2.4.3 Run a stripping cycle with pure nitrogen (no feed)for 7 to 10 min, while ramping temperature to regenerationconditions (600 to 700C).7.2.4.4 After the stripping step is complete, change the gascomposition through both the
45、feed tube and sieve plate to100 % air for regeneration.7.2.5 Deactivation:7.2.5.1 Deactivation time and temperature are specific to theobjectives of the catalyst simulation (732 to 815C). The totaldeactivation time from start to finish is established to achievea certain degree of surface area reduct
46、ion. Therefore, thesteaming time per cycle is variable, but typically 30 to 60 min.7.2.5.2 Ramp the temperature up to deactivation conditions.7.2.5.3 Terminate the air gas flow through the feed tube andthe sieve plate.7.2.5.4 Activate the water pump and adjust the water flowrate to achieve the desir
47、ed partial pressure of steam. 100 %steam is achievable, but 45 to 90 % is more typical forlaboratory simulations.7.2.5.5 Repeat steps 7.2.3.4 through 7.2.5.4 for the numberof desired cycles.7.2.6 At the conclusion of the final deactivation step, coolthe furnace using the forced air circulation syste
48、m.7.2.7 Remove the catalyst.7.2.8 Analyze the deactivated catalyst.7.3 Variations:7.3.1 The temperature of cracking and deactivation, as wellas the partial pressure of steam, are variables that can becustomized as needed.TABLE 1 Standard CPS ProcedureNOTE 1This scheme is considered standard and repr
49、esents the case inwhich the treatment ends in a state of reduction. A similar scheme inwhich the cycles end in oxidation can also be configured.Catalyst pre-treatment 1 h at 204C 400F followed by3hat593C 1100FImpregnation 2000 ppm nickel and 3000 ppm vanadiumPost-treatment 1 h at 204C 400F followed by3hat593C 1100FSteam deactivation 788C 1450F, 50% steam, 0 psig, 20 h (30 cycles)Cycles consist of: 10 min, 50% mass percent N210 min, 50% mass percent 4000 ppm SO2in air10 min, 50 mass percent N210 min, 50 mass percent
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