1、Designation:D720606 Designation: D7206/D7206M 06 (Reapproved 2012)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 orig
2、inal adoption or, in 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.1NOTEUpdated units statement and made a combined standard editorially in Ap
3、ril 2012.1. Scope1.1 This guide covers the deactivation of fluid catalytic cracking (FCC) catalyst in the laboratory as a precursor to small scaleperformance testing. FCC catalysts are deactivated in the laboratory in order to simulate the aging that occurs during continuoususe in a commercial fluid
4、 catalytic cracking unit (FCCU). Deactivation for purposes of this guide constitutes hydrothermaldeactivation of the catalyst and metal poisoning by nickel and vanadium. Hydrothermal treatment is used to simulate the physicalchanges that occur in the FCC catalyst through repeated regeneration cycles
5、. Hydrothermal treatment (steaming) destabilizes thefaujasite (zeolite Y), resulting in reduced crystallinity and surface area. Further decomposition of the crystalline structure occursin the presence of vanadium, and to a lesser extent in the presence of nickel. Vanadium is believed to form vanadic
6、 acid in ahydrothermal environment resulting in destruction of the zeolitic portion of the catalyst. Nickels principle effect is to poison theselectivity of the FCC catalyst. Hydrogen and coke production is increased in the presence of nickel, due to the dehydrogenationactivity of the metal. Vanadiu
7、m also exhibits significant dehydrogenation activity, the degree of which can be influenced by theoxidation and reduction conditions prevailing throughout the deactivation process. The simulation of the metal effects that onewould see commercially is part of the objective of deactivating catalysts i
8、n the laboratory.1.2 The two basic approaches to laboratory-scale simulation of commercial equilibrium catalysts described in this guide are asfollows:1.2.1 Cyclic Propylene Steaming (CPS) Method, in which the catalyst is impregnated with the desired metals via an incipientwetness procedure (Mitchel
9、l method)2followed by a prescribed steam deactivation.1.2.2 Crack-on Methods, in which fresh catalyst is subjected to a repetitive sequence of cracking (using a feed with enhancedmetals concentrations), stripping, and regeneration in the presence of steam. Two specific procedures are presented here,
10、 aprocedure with alternating metal deposition and deactivation steps and a modified Two-Step procedure, which includes a cyclicdeactivation process to target lower vanadium dehydrogenation activity.1.3The values stated in SI units are to be regarded as standard. The values given in parentheses are f
11、or information only.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result i
12、n non-conformance with the standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimita
13、tions prior to use.2. Terminology2.1 Definitions:2.1.1 crack-ontechnique of depositing metals onto a catalyst through cracking of an FCC feed with enhanced metal contentin a fluidized catalyst bed that is at cracking temperature.2.2 Acronyms:2.2.1 E-catequilibrium catalyst from commercial FCCU.2.2.2
14、 FCCfluid catalytic cracking.2.2.3 FCCUfluid catalytic cracking unit.2.2.4 LGOlight gas oil, fluid at 40C, initial boiling point 250C, sulfur content of 2-3 mass percent.3. Significance and Use3.1 This guide describes techniques of deactivation that can be used to compare a series of cracking cataly
15、sts at equilibriumconditions or to simulate the equilibrium conditions of a specific 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 solution.4.5 Nitrogen (N2).4.6 Oxygen (O2), 40 %
16、in nitrogen balance.4.7 Vanadium naphthenate solution.4.8 Cyclo-hexaneCyclohexane.4.9 N-pentanen-pentane.4.10 N-hexanen-hexane.4.11 Water, demineralized.5. Hazards5.1 The operations described in this guide involve handling heated objects, fragile glassware, and toxic organic nickel andvanadium compo
17、unds.5.2 All work with organic metals precursor solutions and other organic solvents should be completed in suitable vented fumehood.5.3 Appropriate personal protection equipment, including chemical goggles, laboratory smock, and disposable gloves should beworn.5.4 Waste organic metal solutions and
18、organic solvents shall be disposed of properly in suitable waste containers and accordingto regulations.5.5 Vented furnaces and hoods should be regularly monitored for proper ventilation before using.5.6 Evaporating dishes should be checked for cracks before use.5.7 The muffle furnace used for the p
19、ost-impregnation thermal treatment of the sample shall be appropriately and adequatelyventilated. Catalyst load sizes should be selected to avoid overwhelming the ventilation capacity of the furnace and allowing fumesto escape into the laboratory.5.8 To avoid the potential hazard of explosion in the
20、 muffle furnace, impregnated samples shall be completely dry of pentaneprior to beginning the thermal post-treatment.5.9 Material safety data sheets (MSDS) for all materials used in the deactivation should be read and understood by operatorsand should be kept continually available in the laboratory
21、for review.6. CPS Method6.1 Summary of PracticeA fresh FCC catalyst is impregnated with nickel, or vanadium, or both. Nickel and vanadium levelsare controlled by a predetermined concentration for the sample. The catalyst is wetted with a mixture of pentane and nickel, orvanadium naphthenate, or solu
22、tions of both and then mixed to dryness. After drying, the sample is thermally treated to removeresidual naphthenates. The sample is then ready for hydrothermal treatment of analysis as desired.6.2 Procedure:6.2.1 Catalyst Pre-treatment Before ImpregnationFor a muffle furnace pre-treatment (standard
23、), place the sample in a dishusing a shallow bed (12 in. maximum). Calcine the sample for 1 h at 204C (400F),400F, then3hat593C (1100F).1100F.The sample is then removed and allowed to cool to room temperature. Catalyst should be returned to a sealed container as soonas it is cool.6.2.2 Steam Deactiv
24、ation Pre-treatmentTypical conditions included hydrothermal treatment for2hat816C(1500F),1500F, 100 % steam, and 0 psi. The catalyst is charged to a pipe reactor, fluidized in air, and then lowered over a 3-hperiod into a 816C (1500F)1500F sand bath furnace. Air flow is switched off and steam introd
25、uced for 2 h. The reactor is thenremoved from the furnace and allowed to cool to room temperature under a nitrogen purge.6.2.3 Preparation of Nickel and Vanadium MixtureThe desired nickel/vanadium levels are calculated for the quantity ofsample to be impregnated. The mass of nickel or vanadium napht
26、henate used to obtain the desired levels on the catalyst sampleare determined as follows:N 5 T/S 3 W (1)D7206_D7206M-06R12E01_1where:D7206/D7206M 06 (2012)12N = naphthenate (nickel or vanadium mass used to obtain the desired metal level on the catalyst),T = target level (the desired mass percent of
27、nickel or vanadium, or both, to be loaded on the catalyst),S = metal solution (the known mass percent of nickel or vanadium 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 dish shall be large e
28、nough to allow for a catalyst bed height of12 in.6.2.4.2 Slowly pour the dissolved metals solution into the dish with catalyst while mixing at the same time. Wash the residualnaphthenate from the glass beaker with pentane and add the wash to the catalyst.6.2.4.3 Stir the sample with a spoonula until
29、 it is completely dry. The appearance of very small lumps in the catalyst after dryingis normal. Large lumps indicate improper drying and shall be avoided. This can be done by adding enough pentane to moisten thecatalyst then repeating the stirring process. High levels of vanadium naphthenate will c
30、ause the sample to appear gummy and isnormal.6.2.4.4 High Levels of Vanadium NaphthenateWhen an impregnation calls for more than 5000 ppm vanadium, theimpregnation should be done in two steps. Otherwise, the volume of naphthenate will overwhelm the volume of catalyst used,affecting the accuracy in r
31、eaching the target level. If over 5000 ppm vanadium is required, divide the required volume of vanadiumnaphthenate in half, impregnate, post-treat, and impregnate again by adding the second half followed by a second post-treat. Ifnickel is also requested, this should be divided and added to the cata
32、lyst along with the vanadium.6.2.4.5 Antimony AdditionIf antimony is requested, triphenylantimony is added to the catalyst after the nickel and vanadiumhave been added and the post treatment has been completed. The impregnation procedure is the same as the nickel and vanadiumimpregnation except that
33、 cyclohexane is used instead of pentane. Antimony will not dissolve in pentane.6.2.5 Catalyst Post-treatment After ImpregnationAfter the impregnated sample has dried, it is placed in a vented mufflefurnace and heat treated to remove the naphthenates and coke formed. The dishes are placed in the furn
34、ace at room temperatureand the temperature is raised to 204C (400F)400F and held at temperature for 1 h. The sample is then calcined at 593C(1100F)1100F for 3 h before being removed and allowed to cool to room temperature.6.2.6 Steam DeactivationSeveral methods exist, each requiring specific conditi
35、ons. An example of such a method is shownin Table 1.7. Crack-on Approach 1: Alternating Cracking and Deactivation Cycles7.1 Summary of Practice:7.1.1 The crack-on units consist of a fluid bed reactor with a fritted gas distributor on the bottom. Nitrogen, air, steam and otherspecialty gasses can be
36、fed through the bottom. Oil can be delivered either from the top or bottom of the reactor depending on themethod. Temperature is controlled by a three zone electric furnace.Adisengaging section on the top of the reactor prevents catalystloss during operation.7.1.2 The crack-on method involves deposi
37、ting metals on the catalyst at cracking temperature using a feed with enhanced metalscontent. The catalyst is regenerated after each cracking cycle.7.1.3 In Crack-onApproach 1, the catalyst is subjected to severe hydrothermal deactivation after each cracking and regenerationcycle. By this method, si
38、gnificant deactivation has taken place by the time the metals addition is complete.7.2 Procedure:7.2.1 Preparation of the CatalystOptionally screen the catalyst to remove coarse contaminants and fine particles that wouldbe lost during fluidization.7.2.2 Prepare the Feed:7.2.2.1 Weigh out and transfe
39、r the appropriate amount of LGO into the feed vessel. The minimum amount of LGO will equalthe number of cracking cycles times the amount fed per cycle.TABLE 1 Standard CPS ProcedureNOTEThis scheme is considered standard and represents the case inwhich the treatment ends in a state of reduction. A si
40、milar scheme inwhich the cycles end in oxidation can also be configured.Catalyst pre-treatment 1 h at 204C (400F) followed by3hat593C (1100F)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 b
41、y3hat593C (1100F)Post-treatment 1 h at 204C 400F followed by3hat593C 1100FSteam deactivation 788C (1450F), 50% steam, 0 psig, 20 h (30 cycles)Steam 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
42、min, 50 mass percent N210 min, 50 mass percent propylene-N2mixture(5% propylene in N2)D7206/D7206M 06 (2012)137.2.2.2 Individually add the organic metal compounds. The mass of each metal added shall be calculated to give the desiredmetal loading on the catalyst. If using this technique to perform an
43、 E-cat simulation, the metal target may have to be substantiallyreduced by 25-50 % of the actual E-cat metal content in order to simulate the deactivation effects discussed in the scope.7.2.2.3 Stir the LGO with a mechanical stirrer, and optionally heat, to insure homogeneity of the mixture througho
44、ut theprocedure.7.2.3 Set up the Reactor System:7.2.3.1 Load the catalyst into the fluidized bed reactor. The amount of catalyst charged depends on the geometry of the reactorvessel.7.2.3.2 Attach all external control, input, exhaust and safety devices.7.2.3.3 Fill the water reservoir to the appropr
45、iate starting point.7.2.3.4 Start the flow of 100 % nitrogen gas through the LGO feed tube.7.2.3.5 Start the flow of 100 % nitrogen through the sieve plate.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 = to
46、tal mass LGO / number of cycles). A good rule of thumb mightbe to set LGO per cycle equivalent to 20-50 % of the catalyst mass.7.2.4.3 Run a stripping cycle with pure nitrogen (no feed) for 7-10 min, while ramping temperature to regeneration conditions(600-700C).7.2.4.4 After the stripping step is c
47、omplete, change the gas composition through both the feed tube and sieve plate to 100 %air for regeneration.7.2.5 Deactivation:7.2.5.1 Deactivation time and temperature are specific to the objectives of the catalyst simulation (732-815C). The totaldeactivation time from start to finish is establishe
48、d to achieve a certain degree of surface area reduction. Therefore, the steamingtime per cycle is variable, but typically 30-60 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 and the sieve plate.7.2.5.4 Activate the water pump
49、and adjust the water flow rate to achieve the desired partial pressure of steam. 100 % steamis achievable, but 45-90 % is more typical for laboratory simulations.7.2.5.5 Repeat steps 7.2.3.4 through 7.2.5.4 for the number of desired cycles.7.2.6 At the conclusion of the final deactivation step, cool the 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 temperature of cracking and deactivation, as well as the part
