1、Designation: D 7206 06Standard Guide forCyclic Deactivation of Fluid Catalytic Cracking (FCC)Catalysts with Metals1This standard is issued under the fixed designation D 7206; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 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 fluid catalyticcracking (FCC) catalyst in the laboratory as a precursor tos
3、mall 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 of this guide consti-tutes hydrothermal deactivation of the catalyst and metal
4、poisoning 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 faujasite (zeolite Y),resulting in reduced crystallinity and surface area. Furtherdec
5、omposition 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 of thezeolitic portion of the catalyst. Nickels principle effect is topoison t
6、he 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 of which canbe influenced by the oxidation and reduction conditions pre-vail
7、ing 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-scale simulationof commercial equilibrium catalysts described in this guide areas
8、 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-on Methods, in which fresh catalyst is subjectedto a repetitive sequence of cr
9、acking (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 and a modified Two-Step procedure, whichincludes a cyclic deactivation proce
10、ss to target lower vanadiumdehydrogenation activity.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsi
11、bility 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. Terminology2.1 Definitions:2.1.1 crack-ontechnique of depositing metals onto a cata-lyst through cracking of an FCC feed with enhanced
12、metalcontent in a fluidized catalyst 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 2-3
13、 mass percent.3. Significance and Use3.1 This guide describes techniques of deactivation that canbe used to compare a series of cracking catalysts at equilibriumconditions or to simulate the equilibrium conditions of aspecific commercial unit and a specific catalyst.4. Reagents4.1 Feed, VGO.4.2 Feed
14、, LGO.4.3 Hydrogen (H2), 42.8 % in nitrogen balance.4.4 Nickel naphthenate or nickel octoate solution.4.5 Nitrogen (N2).4.6 Oxygen (O2), 40 % in nitrogen balance.4.7 Vanadium naphthenate solution.1This guide is under the jurisdiction of ASTM Committee D32 on Catalysts andis the direct responsibility
15、 of Subcommittee D32.04 on Catalytic Properties.Current edition approved April 1, 2006. Published April 2006.2Mitchell, B. R., Industrial and Engineering Chemistry Product Research andDevelopment, 19, 1980, p. 209.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
16、PA 19428-2959, United States.4.8 Cyclo-hexane.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 andvanadium compounds.5.2 All work with organic metals precursor soluti
17、ons 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 solutions and organic solvents shallbe disposed of properly in suitabl
18、e 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 for the post-impregnationthermal treatment of the sample shall be
19、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 explosion in the mufflefurnace, impregnated samples shall be completely dry
20、 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 thelaboratory for review.6. CPS Method6.1 Summary of PracticeA fresh FCC cat
21、alyst 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 solutions of both and thenmixed to dryness. After drying, the samp
22、le 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 (standard), place the sample in adish using a shallow bed (12 in. maximum)
23、. 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-treatmentTypical condi-tions included hydrothermal treatment for2hat81
24、6C(1500F), 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 removedfrom the furnace and allowed to cool to room temper
25、atureunder 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 levels on the catalystsample are determined as follows:N 5 T/
26、S 3 W (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 known mass percent of nickel orvanadium in the naphthenate so
27、lution), 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 metals solution into thedish with catalyst while mixing at the
28、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 normal. Large lumps indicate improper drying andshall be avo
29、ided. 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 animpregnation calls for more than 5000 ppm vanadium, thei
30、mpregnation 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 ofvanadium naphthenate in half, impregnate, post-treat, andimp
31、regnate 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.6.2.4.5 Antimony AdditionIf antimony is requested, triph-enylantimony is added to the catalyst after the nickel andvanadium hav
32、e 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 pentane.6.2.5 Catalyst Post-treatment After ImpregnationAfterthe impregnated sample has
33、 dried, it is placed in a ventedmuffle furnace and heat treated to remove the naphthenates andcoke formed. The dishes are placed in the furnace at roomtemperature and the temperature is raised to 204C (400F) andheld at temperature for 1 h. The sample is then calcined at593C (1100F) for 3 h before be
34、ing removed and allowed tocool to room temperature.6.2.6 Steam DeactivationSeveral methods exist, each re-quiring specific conditions. An example of such a method isshown in Table 1.D72060627. Crack-on Approach 1: Alternating Cracking andDeactivation Cycles7.1 Summary of Practice:7.1.1 The crack-on
35、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 reactordepending on the method. Temperature is controlled by a threezone electric f
36、urnace. 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. The catalyst is regenerated after each crackingcycle.7.1.3 In Crack-on
37、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 Procedure:7.2.1 Preparation of the CatalystOptionally screen thecatalyst to remo
38、ve 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 number of cracking cycles times the amount fed percycle.7.2.2.2 Individuall
39、y 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-tially reduced by 25-50 % of the actual E-cat metal content inorder to s
40、imulate 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 Load the catalyst into the fluidized bed reactor. Theamount of catalyst ch
41、arged 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 % nitrogen gas through theLGO feed tube.7.2.3.5 Start the flow of 100 % nitrogen th
42、rough the sieveplate.7.2.4 Metallation and Regeneration:7.2.4.1 Set the reactor temperature (500-530C).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 be to set LGO per cycle equivalent to 20-50 % of thecatalyst mass.7.2.4.3 Run
43、 a stripping cycle with pure nitrogen (no feed)for 7-10 min, while ramping temperature to regenerationconditions (600-700C).7.2.4.4 After the stripping step is complete, change the gascomposition through both the feed tube and sieve plate to100 % air for regeneration.7.2.5 Deactivation:7.2.5.1 Deact
44、ivation time and temperature are specific to theobjectives of the catalyst simulation (732-815C). The totaldeactivation time from start to finish is established to achievea certain degree of surface area reduction. Therefore, thesteaming time per cycle is variable, but typically 30-60 min.7.2.5.2 Ra
45、mp 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 desired partial pressure of steam. 100 %steam is achievable, but 45-90 % is more typical for labor
46、atorysimulations.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 system.7.2.7 Remove the catalyst.7.2.8 Analyze the deactivated catalyst.7.3 Variations:7.3.1 The temp
47、erature of cracking and deactivation, as wellas the partial pressure of steam, are variables that can becustomized as needed.7.3.2 Heavier feeds can be used in Approach 1 than theLGO cited here. Heavier, resid-containing oils would requireheating of the pump and delivery lines.7.3.3 When applying a
48、high metal content in Approach 1, itis advisable to add catalyst in stages. In this variation, a portionof the catalyst charge will have a relatively low metal content,compared to the metal content of the bulk.NOTE 1During the deactivation cycles, a variety of special gasses thatmight be found withi
49、n an FCCU regenerator (for example, SOx) can beadded with the steam-air mixture.8. Crack-on Approach 2: Two-Step Cyclic Deactivation(TSCD)8.1 Summary of Practice:8.1.1 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 reactordepending on the method. Temperature is controlled by a threeTABLE 1 Standard CPS ProcedureNOTEThis scheme is considered standard and represents the case
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