Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
3 ,~
~ACKGRO~ND OF THE INVENTION
This invention relates to an improved catalyst, one or more
methods for its preparation, one or more methods for treatment,
and a process for its use in the conversion of reduced crude or
crude oil to liquid transportation and/or heating fuels. ~ore
particularly, the invention is related to a catalyst composi-
tion comprising a catalytically active crystalline alumino-
silicate zeolite uniformly dispersed within a matrix containing
a metal additive as a select metal, its oxide or salts to immo-
bilize the vanadium oxide deposited on the catalyst during pro-
cessing. A further embodiment of this invention is the addi-
tion of the metal additive for vanadia immobilization during
catalyst manufacture, after spray drying by impregnation, or at
any point in the reduced crude processing cycle.
The introduction of catalytic cracking to the petroleum indus-
try in the 1930's constituted a major advance over previous
techniques with the object to inçrease the yield of gasoline
and its quality. Early fixed bed, moving bed, and fluid bed
catalytic cracking FCC processes employed vacuum gas oils ~VGO)
from crude so~rces that were considered sweet and liyht. The
terminology o~ sweet refers to low sulfur content and light
refers to the amount of material boiling below approximately
1, 000--1, 025F .
The catalysts employed in early homogeneous fluid dense beds
were of an amorphous siliceous material, prepared synthetically
,' ~
1~37~12
or from naturally occurring materials activated by acid leach
ing.Tremendous strides were made in the 1950's in FCC technol-
ogy as to metallurgy, processing equipment, regeneration and
new more-active and more stable amorphous catalysts. However,
increasing de~and with respect to quantity of gasoline and
increased octane number requirements to satisfy the new high
horsepower high compression engines being promoted by the auto
industry, put extreme pressure on the petroleum industry to
increase FCC capacity and severity of operation.
A major breakthrough in FCC catalysts came in the early 1960's,
with the introduction of molecular sieves or zeolites, which
were incorporated into the matrix of amorphous and/or amor-
-phous/kaolin materials constituting the FCC catalysts of that
time. These new zeolitic catalysts, containing a crystalline
alumino-silicate zeolite in an amorphous, amorphous/kaolin,
matrix of silica, alumina, silica-alumina, kaolin, etc. were at
least i,000-10,000 times more active for cracking hydrocarbons
than the earlier amorphous, amorphous/kaolin containing silica-
alumina catalysts. This introduction of zeolitic crackingcatalysts revolutioni~ed the ~luid catalytic cracking process.
New innovations were developed to handle these high activities,
such as riser cracking, shortened contact times, new regenera-
tion processes, new improved zeolitic catalyst developments,etc.
The overall result (economic) of these zeolitic catalyst devel-
opments was to give the petroleum industry the capability
1~3~;'92
of greatly increasing throughp~lt of feedstock with increased
conversion and selectivity while employing the same units with
out expansion and without requiring new unit construction.
The newer catalyst developments revolved around the development
of various ~eolites such as type X, Y, faujasite; increased
thermal steam stability through the inclusion of rare earth
ions or ammonium via ion-exchange techniques and the develop-
ment of more attrition resistant matrices.
10After the introduction of zeolitic containin~ catalysts the
petroleum industry began to suffer from crude availability as
to quantity and quality accompanied by increasing demand for
gasoline with increasing octane value. The world crude supply
picture changed in the late 1960's - early 1970's. From a sur-
plus of light-sweet crudes the supply situation changed to a
tighter supply with an ever increasing amount of heavier crudes
with higher sulfur contents. These heavier and high sulfur
crudes presented processing problems to the petroleum refiner
in that these heavier crudes invariably also contained much
higher metals and Conradson carbon values, with accompanying
significan~ly increased asphaltic content.
Practionation of the total crude to yield cat cracker charge
stocks also required much better control to ensure that metals
and Conradson carbon values were not carried overhead to con-
taminate the FCC charge stock.
The effects of metals and Conradson carbon on a ~eolitic
_ 5 _
1~ ~379Z
containing FCC catalyst have been described in the litera~ure
as to their highly unfavorable effect in lowering catalyst
activity and selectivity for gasoline production and their
equally harmful effect on catalyst life. In particular, we
S have shown that vanadia, at high concentrations in the feed, is
especially detrimental to catalyst life.
As mentioned previously, these heavier crude oils also
contained more of the heavier fractions and yielded less or a
lower volume of the high quality FCC charge stocks which norm-
ally boils below 1025F, and usually is so processed, as to
contain metal contents below 1 ppm, preferably 0.1 ppm and
Conradson carbon values substantially below 1.
With this increasing supply of heavier crudes, which meant
lowered yields of gasoline and the increasing demand for liquid
transportation fuels, the petroleum industry began a search for
processing schemes to utilize these heavier crudes in producing
gasoline. Most of these processing schemes have been described
in the literature. These include Gulf's Gulfining and Union
Oil Unifining processes for ~reating residuum, UOP's Aurabon
process, Hydrocarbon Research's H Oil process, Ex~on's
Flexicoking process to produce thermal gasoline and coke,
H-Oil's Dynacracking and Phillip's Heavy Oil Cracking (HOC).
These processes utilize thermal cracking or hydrotreating fol-
lowed by FCC or hydrocracking operations to handle the higher
content of metals (Ni-V-Fe-Cu-Na) and high Conradson carbon
values of 5-15~ Some of the drawbacks of this type of
-- 6 --
1~83~9;2
processing are as follows: Coking yields thermally cracked
gasoline which has a much lower octane value than cat cracked
gasoline and is unstable due to the production of gum from
diolefins and requires further hydrotreating and reforming to
produce high octane product; gas oil quality is degraded due to
thermal reactions to produce a product containing refractory
polynuclear aromatics, high Conradson carbons are highly
unsuitable in catalytic cracking; hydrotreating requires expen-
sive high pressure hydrogen, special alloy multi-reactor sys-
tem, costly operations, and a separate costly facility for the
production of hydrogen.
To better understand the reasons why the industry has
progressed along thé processing schemes described, one must
understand the known and established effects of contaminant
metals (Ni-V-Fe-Cu-Na) and Conradson carbon on the zeolitic
containing cracking catalysts and the operating parameters of a
FCC unit. Metal content and Conradson carbon are two very
effective restraints on the operation of a FCC unit or a
Reduced Crude Conversion unit towards obtaining maximum conver-
sion, selectivity and life. As metals and Conradson carbon
incre~se, the operating capacity and efficiency of a FCC unit
is greatly and final.ly adversely affected or made impossible,
although there is enough hydrogen in the feed to produce only
toluene and pentane, if a highly selective catalyst could be
devised. ~
3'79;i~
The effect of increasing Conradson carbon is to increase that
portion of the feedstock converted to carbon deposited on the
catalyst. In typical VGO operations employing a ~eolite con-
taining catalyst in a FCC unit, the amount of coke deposited on
the catalyst averages around about 4-S wt~ of feed. This coke
production has been attributed to four different coking mechan-
isms, namely, contaminant coke (from metal deposits), catalytic
coke (acid site cracking), entrained hydrocarbons (pore struc-
ture adsorption - poor stripping) and Conradson carbon. In the
case of processing higher boiling fractions, e.g., reduced
crudes, residual fractions, topped crude, etc., the coke pro-
duction based on feed is the summation of the four types pres-
ent in VGO processing plus the higher Conradson carbon value,
higher boiling unstrippable hydrocarbons and coke associated
with high nitrogen containing molecules which irreversibly
adsorb on the catalyst. Thus, coke production on clean catal-
yst, when processing reduced crudes, is approximately 4 wt%plus the Conradson carbon value of the feedstock. Thus, there
has been postulated, two other types of coke formers present in
reduced crudes in addition to the four present in VGO andthey
are: 1) adsorbed and absorbed high boiling hydrocarbons not
r~moved by nor~al-efficient stripping and, 2) high molecular
weight nitrogen containing hydrocarbon compounds adsorbed on
the catalyse's acid sites. Both of thse two new types of cok-
ing producing phenomena add greatly to the complexity of residprocessing.
- 8 -
-
379Z
The spent co~ed catalyst i9 brought back to equilibrium activ-
ity by burning off the deactivating coke in a regeneration zone
in the presence of air and recycled back to the reaction 20ne.
The heat generated during regeneration is removed by the catal-
yst and carried to the reaction zone for vaporization of thefeed and to provide heat for the endothermic nature of the
cracking reaction. The temperature in the regenerator is norm-
ally limited because of metallurgy limitations and the thermal-
steam stability of the catalyst.
The thermal-steam stability of the zeolite containing catalyst
is determined by the temperature and steam partial pressure at
which the zeolite begins to rapidly lose its crystalline struc-
ture to yield a low activity amorphous material. The presence
of steam is highly critical and is generated by the burning of
adsorbed carboneceous material which has a high hydrogen con-
tent. This carboneceous material is principally the high boil-
ing adsorbed hydrocarbons with boiling points as high as 1500-
1700F or above that have a modest hydrogen content and the
high boiling nitrogen containing hydrocarbons as well as rela-
ted porphyrins and asphaltenes.
As the Conradson carbon value of the feedstock increases, coke
production increases and this increased load will raise the
regeneration temperature; thus the unit is limited as to the
amount of feed that can be processed, due to the Conradson car-
bon content. Earlier VGO units opera~ed with the regenerator
at 1150-1250F. A new development in reduced crude processing,
_ 9 _
~83~79Z
namely, Ashland Oil's "Reduced Crude Conversion Process" (pend-
eanadian Patent 1,168,176 can operate at regenerator tem-
peratures in the range of 1350-1400F. But even these higher
regenerator temperatures place a limit on the Conradson carbon
value of the feed at approxirnately 8. This level is control-
ling unless considerable water is introduced to further control
temperature, which addition is practiced in the RCC process.
.. l
The metal containing fractions of reduced crudes contain Ni-
V-~e-Cu, present in porphyrins and asphaltenes. These metal
containing hydrocarbons are deposited on the catalyst during
processing and are cracked in the riser to deposit the metal or i
carried over by the spent catalyst as the metallo-porphyrin or
asphaltene and converted to the metal oxide during regenera
tion. The adverse effects of these metals as taught in the
literature are to cause non-selective or degradative cracking 1,
and dehydrogenation to produce increased coke and light gases
such as hydrogen, methane and ethane which affects selectlvity,
resulting in and poor yield and ~uality of gasoline and light
cycle oil. The increased production of light gases, while
impairing the yield and selectivity structure of the process, i
also puts an increased demand on compressor capacity. The ¦
increase in coke production, in addition to its negative impact
on yield, also affects catalyst activity-selectivity, greatly
increases regenerator air demand and compressor capacity and ~I
uncontrollable and dangerous regenerator temperature. ~ 1,
- 10 -
.. ~
,
3179Z
These problems of the prior art have been greatly minimized by
the development at Ashland Oil, Inc, of the Reduced Crude
Conversion Process, see Canadian Paten-ts 1,167,793 & 1,16~,176
094~ 6. This new process can handle reduced crudes or crude
oils containing high metals and Conradson carbon values previ-
ously not susceptible to direct processing. Normally, these
cr~des require e~pensive vacuum distillation to isolate suit-
able feedstocks, and producing as a by product, high sulfur
containing vacu~;m still bottoms. The RCC process avoids all of
Ithis.
It was early noted that reduced crudes with high nickel to
vanadium levels presented less problems as to catalyst deac-
tivation at high metal on catalyst contents, e.g., 5,000-
10,000 ppm, at elevated regenerator temperatures. However,
when reduced crudes ~ith high vanadium to nickel levels are !
2Q processed over zeolite containing catalysts, especially at high
- vanadium levels on the catalyst, rapid deactivation of the zeo-
lite containing catalyst is noted. This deactivation manifests i
itself as a rapid loss of the zeolite structure at vanadium
levels, above 5,000 ppm approaching 10,000 ppm at elevated
regenerator temperatures. Published accounts report that it is
impossible to operate at vanadium levels higher than 10,000 ppm
because of this factor. To date, this rapid vanadium deactiva-
tion at high vanadium levels has only been retarded by lowering
regenerator tempertures and increasing the addition rate of
virgin catalyst. ,j
., ,
, J
;3~79;~:
SU~IMARY OF THt~ INVENTION
____
The problems of the prior art are now overcome in a process
employing the catalyst and select metal additive of this inven-
tion which allows the processing of a reduced crude or crude
oil of high metals - high vanadium to nickel ratio and
Conradson carbon value. A reduced crude or crude oil having a
high metal and Conradson carbon value is contacted with a zeo-
litic containlng catalyst of high area at tempertures above
about 950F. Residence time of the oil in the riser is below 5
seconds, preferably 0.5 - 2 seconds. The particle size of the
catalyst is approximately 20 to 150 microns in size to ensure
adequate fluidization properties.
The reduced crude - crude oil is introduced at the bottom of
the riser and contacts the catalyst at a temperature of 1200-
1400F to yield a temperature at the exit of the riser in the
reactor vessel of approximately 950-1100"F. Along with the
reduced crude or crude oil, water, steamV naphtha, flue gas,
etc., may be introduced to aid in vaporiz.ation and act as a
lift gas to control residence time and provides other benefits
described in Canadian Patent 1,168,176.
Spent catalyst is rapidly separated from the hydrocarbon vapors
at the exit of the riser by employing the vented riser concept
developed by Ashland Oil, Inc. U. S. Patent No. 4,066,533.
During the coursl~ of the reaction in the riser, the metai and
Conradson carbon compounds are deposited on the catalyst.
; - 12 -
.
379~
After separation in the vented riser, the spent catalyst is
deposited as a dense but fluffed bed at the bottom of the reac-
tor vessel, t~ansferred to a stripper and then to the regenera-
tion zone. The spent catalyts is contacted with an oxygen con-
taining gas to remove the carboneous material through combus-
tion to carbon oxides to yield a regenerated catalyst contain-
ing less than 0.1 wt~ carbon, preferably less than 0.05 wt%
carbon. The regenerated catalyst is then recycled to the bot-
tom of the riser where it again joins high metal and Conradson
carbon containing feed to repeat the cycle.
At the elevated temperatures encountered in the regeneration
zone, the vanadium deposited on the catalyst is converted to
vanadium oxides, in particular, vanadium pentoxide. The melt-
ing point of vanadium pentoxide is much lower than temperatures
encountered in the regeneration zone. Thus, it can become
mobile, flow across the catalyst surface, cause pore plugging,
particle coalascence, and more importantly, enter the pores of
the zeolite, where our studies have shown that it catalyzes
irreversible crystalline collapse to an amorphous material.
This application describes a new approach to offsetting the
adverse effect of vanadium pentoxide by the incorporation of
select metals, metal oxides or their salts into the catalyst
- matrix during manuracture, by impregnation techniques after
spray drying, or added during processing at select points in
the unit to affect vanadium immobilization through compound or
- 13 -
~18,37~Z
complex formation. These compound~s or complexes of vanadia
with metal additives, serve to immobilize vanadia by creating
high melting point complexes or compounds of vanadia which are
higher than the temperatures encountered in the regeneration
zone.
1~379Z
DESC~IPTION OF PREFFRRED EM~ODIMENTS
The select catalysts of this invention will include solids of
high catalytic activity such as zeolites in a matrix of clays,
kaolin, silica, alumina, smectites, and other 2-layere~1 lamel-
lar silicates, silica-alumina, etc. The surface area of these
catalysts would preferably be above l00 m2/g, have a pore
volume in excess of 0.2 cc/g and a micro-activity or conversion
value as measured by the ASTM test method No. D3907-80 of at
least or greater than 60, and preferably above 65.
To an aqueous slurry of the raw matrix matrix material and zeo-
lite is mixed the metal additive to yield approximately 1-20
wt% concentration on the finished catalyst. The metal additlve
can be added in the form of a water soluble compound such as
the nitrate, halide, sulfate, carbonate, etc., and/or as the
oxide or hydrous gel. This mixture is spray dried to yield the
finished promoted catalyst as a microspherical particle of l0-
200 microns in size with the active metal additive depositedwithin the matrix and/or the outer surface of the catalyst par-
ticle. Since the concentration of vanadia on the spent catal-
yst can be as high as ~ wt3 of particle weight, the concentra-
tion of metal additive will be in the range of 1-6 wt~ as the
metal element to maintain at least a one to one atomic ratio of
vanadium to metal additive at all times. The catal~st can be
impregnated with the metal additive after spray drying, employ-
ing techniques well ~nown in the art, or as metioned above, an
active gelatinous precipitate, such as titania or zirconia gel,
- 15 -
., I
1~;379Z
or other gels can be added to the matrix gel prior to spr~y
drying.
It is not proposed to define the exact mechanism for the immo
bilization of vanadia but the metal additives of this invention
will form compounds or complexes with vanadia that have higher
melting points than the temperatures encountered in the regen-
eration zone. The one to one atomic ratio was chosen as mini-
mum, although initially, the metal additive may be considerably
above this ratio if it is incorporated in the catalyst prior touse, after which the ratio of additive to vanadia will decrease
as vanadia is deposited on the catalyst. Thus, at this one to
one ratio (50~ vanadium - 50~ metal additive) the melting point
of the binary reaction product is generally well above operat-
ing conditions. Alternatively, the metal additive may be addedat the same rate as the metal content of the feed to maintain a
one to one atomic ratio. This experimental approach was
employed as a practical matter to uncover and confirm suitable
metals - metal oxides which can form binary reaction mixtures
with vanadium pentoxide so as to yeild a solid compound that
has a melting point of approximately 1800F or higher at this
one to one ratio. Search for this high melting point reaction
product was initiated to help ensure that vanadia would not
melt, flow and enter the zeolite cage structure to cau~e
destruction of the zeolite's crystalline structure as previous-
ly described. The metal-metal oxides of this invention include -
the following yroups and their active elements from the
Pericdic chart of the elements:
- 16 -
,;
~1~i379~:
TA3LE A
M.P. of 1/1 Mixture - F
Group IIA Mg, Ca, Sr, ~a 1740-1900
Group IIIB Sc, Y, La lB00-2100
Group IVB Ti, Zr, H 1700-2000
Group VB Nb, Ta lB00-2000
Group VII~ Mn 1750
Group VIII Fe, Co, Ni 1600-1800
Group IIIA In, Tl 1800
Group VA Bi 1800
Group VIA Te 1500
Lanthanide Series Ce, Pr, etc. 2100
Actinide Series Th, U, etc.
The reaction of the metal additive with vanadia generally
yields a binary reaction mixture. This invention also recog-
nizes that mixtures of these additive metals with vanadia can
occur to form high melting ternary and quaternary reaction mix-
tures, e.g., Barium vanadium titanate, and in addition, these
ternary and quaternary reaction mixtures can occur with metals
not covered in the Groups above. Further, in this invention we
have covered the lower oxidation states of vanadium as well as
vanadium pentoxide. However, in processing a sulfur containing
feed and regeneration in the presence of an oxygen containing
gas vanadium will also iikely form such compounds as vanadium
sulfides, sulfates, and oxysulfides which can also form binary,
ternary, etc., reaction mixtures with the metal additives of
this invention as mixed oxides and sulfides.
If the metal additive is not added to the catalyst during
manufacuture then it can be added by impregnation technques to
the spray dried microspherical catalyst particles. In
, ~ .
379Z
addition, the ~etal additive can be added as an aqueous o~
hydrocarbon solution or volatile compound during the processing
cycle at any point of catalyst travel in the processing unit.
This would include but not be limited to addition of an aqueous
solution of the inorganic metal salt or a hydrocarbon solution
of organo-metallic compounds at the riser wye 17, along the
riser length 4, the dense bed 9 in the reactor vessel 5, strip-
per 10 and 15, regenerator inlet 14, regenerator dense bed 12,
or regenerated catalyst standpipe 16.
The selective catalyst of this invention with or without the
metal additive is charged to a Reduced Crude Conversion (RCC)
type unit as autlined in Figure 1. Catalyst particle circula-
tion and operating parameters are brought up to process condi-
tions by methods well ~nown to those skilled in the art. The
equilibrium catalyst at a emperature of 1100-1400F conta~ts
the reduced crude of high metals and Conradson carbon values at
riser wye 170 The reduced crude can contain steam and/or flue
gas injected at point 2, water and/or naphtha injected at point
3 to aid in vaporization, catalyst fluidization, and control-
ling contact time in riser 4. The catalyst and vaporous hydro-
carbons travel up riser 4 at a contact time of 0.5-5 seconds,
preferably 1-2 seconds. The catalyst and vaporous hydrocarbons
are separated in vented riser outlet 6 at a final rection tem-
perature of 950-1100F. The vaporous hydrocarbons are trans-
ferred to cyclone 7 where any entrained catalyst fines are
separated and the hydrocarbon vapors are sent to the fractiona-
tor via transfer line 8. The spent catalyst is then
- 18 -
l~L~37~Z
transferred to stripper lO for removal of entrained hydrocarbon
vapors and then to regenerator vessel 11 to form dense bed 12.
An oxygen containing gas such as air is admitted to the bottom
of dense bed 12 in vessel ll to combust the coke to carbon
oxides. The resulting flue gas i5 processed through cyclones
and exits from regenerator vessel ll via line 13. The regen-
erated catalyst is transferred to stripper 15 to remove any
entrained combustion gases and then transferred to riser wye l~
via line 16 to repeat the cycle.
At such time that the metal level on the catalyst becomes
intolerably high such that catalyst activity and selectivity
declines, additional catalyst can be added and the deactivated
catalyst withdrawn at addition-withdrawal poin~ 18 into dense
bed 12 and at addition-withdrawal point 19 into regenerated
catalyst standpipe 16. Additions point 18 and 19 can also be
utili~ed to add metal additive promoted catalyst. In the case
of a non-promoted catalyst, the metal additive as an aqueous
solution or an organo-metallic compound in aqueous or hydrocar-
bon solvents can be added at addition points 18 and l9 as well
as at addition points 2 and 3 on feed line l, addition point 20
in riser 4, addition point 21 to the bottom of vessel 5 intodense bed 9. The addition of the metal additive is not limited
to these locations but can be practiced at any point in the
reduced crude - catalyst processing cycle.
- 19 -
3179Z
The regenerator vessel, as illustrated in Figure 1, is a simple
one zone-dense bed type. The regenerator section is not limi-
ted to this example but can exist of two or more zones, stacked
or side by side arrangement, with internal and/or external eir-
eulation transfer lines from zone to zone.
In some of the previous reduced crude proeesses, aceeptable
eatalyst life and seleetivity eould be obtained with redueed
erude feedstocks eontaining low levels of metal contamination,
and having a high niekel to vanadium ratios. However, as the
vanadium content on the eatalyst inereased or with high vana-
dium to niekel ratio reduced crude catalyst activity and selee-
tivity decrease rapidly and can only be corrected by economi-
cally unacceptable increased catalyst addition rates. Having
thus described the observed detrimental effects of vanadium and
nickel, the catalyst, metal additive promoters and process of
this inven~ion, the following examples are provided to illu-
strate the effeet of vanadia flowing and eausing eatalyst deae~
tivation through destruetion of the zeolite's erystalline
strueture and steps taken to prevent its occurenee.
- 20 -
37~Z
EXAr~!PLES
The determination that vanadia deposited on a fluid catalytic
cracking catalyst would, under the conditions of elevated tem-
peratures in the regenerator zone, enter the zeolite and
catalyze the destruction of its crystalline structure to the
less active amorphous material, with subsequent low activity
and selectivity, was noted in our reduced crude demonstration
unit.
This phenomenum was then evaluated in the laboratory by depos-
iting vanadium and nickel, singly on a specially chosen canadi-
date catalyst to study its resistance to severe thermal and
steaming conditions. As noted in Figure 2 through S, and
Tables l and 2, the overall effect of nickel is to neutralize
acid sites, and increase coke and gas production but little or
no destruction of the zeolite crystalline cage structure was
observed. Vanadium on the other hand, was irreversibly destruc-
tive. At suitably severe conditions, as the vanadia content
was increased, zeolite content decreased proportionally to the
point that at approximately the l wt% vanadium level the zeo~
lite crystalline structure was completely destroyed after 5
hours at 1450F in steam leading to a completely deactivated
catalyst.
The determination that vanadia deposited on a catalyst would
flow and cause coalescence between catalyst particles at regen-
erator temperatures, and what elements and their salts would
- 21 -
3792
prevent this processs were studled by three methods; namely,
the clumping or lump formation technique, vanadia diffusion
from or eompound formation with a metal additive in a alumina-
ceramic crucible, and through speetroscopie studies and differ-
ential thermal analyses of vanadia-metal additive mixtures.
CLUMPING TES_
A elay, spray dried to yield microspherical particles in 20-150
micron size, had vanadia deposited upon it in varying concen-
trations. The clay, free of vanadia, and those containing
varying vanadia coneentrations were plaeed in individual
eeramic crucibles and ealcined at 1400F in air for two hours.
At the end of this time period the erueibles were withdrawn
from the muffle furnace and eooled to room temperature. The
surfaee texture and flow eharaeteristies of these samples were
noted and the results are reported in Table 3.
TABLE 3
V25 Surfaee
25Concentration - ppm Texture Flow Charaeteri ties
0 Free Free flowing
1,000-5,000 Surface Clumped Broke erust-free flowing
5,000-20,000Sur~aee Clumped Total elumping-no flow
As shown in Table 3, the elay free of vanadia does not form any
erust or elumps or fused partieles at temperatures eneountered
in the regenerator seetion of the proeess deseribed in this
- 22 -
"
79~
invention. At vanadia concentrations above 5,000 ppm the clay
begins to clump and bind badly and does not flow at all.
While liquid at operating temperature, manifestation of this
phenomenum is demonstrated by the finding that solidlfication
point in a crucible, or the operating unit is cooled down in
order to facilitate entrance to the unit for cleaning out
plugged diplegs and other repairs. This phenomenum also makes
a turn-around timely and complex, as this material must be
chipped out.
- 23 -
3 1~3 ~92
CR~CI3LE DIFF~SION - COMPO~ND FORMATION
.
An extension of the clumping test is the use of a ceramic-
alumina crucible to determine whether vanadia react with given
metal additive.If vanadia does not react with the metal addi-
tive or only a small amount of compound formation occurs, thenthe vanadia has been observed to diffuse through and over the
porous alumina walls and deposit as a yellowish to orange
deposit on the outside wall of the crucible. On the other
hand, when compound formation occurs, there is little or no
vanadia deposits on the outside of the crucible wall. Two ser-
ies of tests were performed. In the first series shown in Table
4, a 1/1 mixture by weight of vanadia pentoxide and the metal
additive waS placed in the crucible and heated to 1500F in air
for 12 hours. Compound formation or vanadia diffusion was
noted.
TA3LE 4
1 Par~ V2O5 + 1 Part Metal Additive
1500F - Air - 12 Hours
Diffusion ofCompound
Metal Additive _ adium Formation
Titania No Yes
Manganese Acetate No Yes
3~ Lanthanum Oxide No Yes
Alumina Yes No
Barium Acetate No Yes
Copper Oxide Yes Partial
- 24 -
~379~
In the second series of tests a vanadia contalning material was
tested in a similar manner. A one to one ratio by weight of
the vanadia containing material and the metal additive were
heated to 15003F in air for 12 hours. The results are shown in
Table 5.
TA3LE 5
l Part V2O5 - Catalyst ~ 1 Part Metal Additive
1500F - Air 12 Hours
Vanadia Metal Particle
Concentration, ppm Additive Formation
24,000 None Yes
l524,000 Calcium Oxide No
24,000 Magnesium Oxide No
24,000 Manganese Oxide No
The study of the capability of certain elements to immobilize
vanadium pentoxide was extended to DuPont differential thermal
analyses (DTA), X-ray diffraction (XRD~ and scanning electron
microscope tSEM) instruments. The meta:L additives studied on
the DTA showed that titania, barium oxide, calcium oxide, iron
oxide and indium oxide all were excellent additives for the
formation of high melting metal vanadates, with melting points
of 1800F or higher. Copper and manganese gave intermediate
results with compounds melting at approximately 1500P. Poor
results were obtained with materials such as lead oxide,
molybdena, tin oxide, chromia, zinc oxide, cobalt oxide, cadi-
mium oxide and some of the r~re earths.
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379Z
The material reported and produced in Table 5, namely 24,000
ppm vanadia on clay with no metal additive, was fired at 1500F
and then studied in the SEM. The fused particles initially
gave a picture of fused particles. However, as the material was
continuously bombarded, the fused particles separated due to
the heat generated by the bombarding electrons. One was able
to notice the melting and flowing of vanadia with the initial
single fused particles separating into two distinct microspher-
ical particles.
An example of our XRD work is the identification of the com-
pound formed when manganese acetate reacted with vanadium pent-
oxide. This compound has been tentatively identified as
Mn2V27 '
The matrix material for the catalyst of this invention should
possess good hydro-thermal stability. Examples of materials
exhibiting relatively stable pore characteristics are alumina,
silica-alumina, silica, clays such as kaolin, meta-kaolin, hal-
loysite, anauxite, dickite and/or macrit:e, and combinations of
these materials. Other clays, such as montmorillonite, may be
added to increase the acidity of the matrix. Clay may be used
in natural state or thermally modified. The preferred matrix
of U. S. Patent No. 3,034,g94 is a semisynthetic combination of
clay and silica-alumina. Preferably the clay is mostly a kao-
linite and is combined with a synthetic silica-alumina hydrogel
or hydrosol. This synthetic component forms preferably about
lS to 75 percent, more preferably about 20 to 25 percent, of
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379~
the formed catalyst by weight. The proportion of clay is such
that the catalyst preferably contains after forming, about 10
to 75 percent, more preferably about 30 to S0 percent, clay by
weight. The most preferred composition of the matrix contains
approximately twice as much clay as synthetically derived
silica-alumina. The synthetically derived silica-alumina
should contain 55 to 95 pereent by weight of silica (SiO2),
preferably 65 to 85 percent, most preferably about 75 percent.
Although catalysts wherein the gel matrix consists entirely of
silica gel are also to be ineluded. After introduetion of the
zeolite and/or metal additive, the eomposition is preferably
slurried and spray dried to form catalyst mierospheres. The
particle size of the spray dried matrix is generally in the
range of about 5 to 160 microns, preferably 40 to 80 microns.
Generally speaking, the finished eatalyst will also eontain
from 5 to 50% by weight of rare earth or ammonia exehanged
sieve of both X or Y variety, preferably about 15-45~ by weight
and most preferably 20-40% by weight. To further enhance the
eatalyst, rare earth exchanged sieve may be caleined and fur-
ther exchanged with rare earth or ammonia to create an excep-
tionally stable sieve.
Various processas may be used in preparing the synthetically
silica-alumina, sueh as those described in U. S. Patent No.
3,034,994. One of these processe~ involves gelling an alXali
metal silicate with an inorganic acid while maintaining the p~
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'3L1~3379Z
on the alkaline side. An aqueous solution of an acidic alum~-
num salt is then intimately mixed with the silica hydrogel 50
that the aluminum salt solution fills the silica hyclrogel
pores. The aluminum is thereafter prscipitated as a hydrous
alumina by the addition of an alkaline compound.
As a specific example of this method of preparation, a silica
hydrogel is prepared by adding sulfuric acid with vigorous agi-
tation and controlled temperature time and concentration condi-
tions to a sodium silicate solution. Aluminum sulfate in water
is then added to the silica hydrogel with vigorous agitation to
fill the gel pores with the aluminum salt solution. An ammoni-
um solution is then added to the gel with vigorous agitation toprecipitate the aluminum as hydrous alumina in the pores of the
silica hydrogel, after whirh the hydrous gel is processed, for
instance, by separating a part of the water on vacuum filters
and then drying, or more preferably, by spray drying the
hydrous gel to produce microspheres. The dried product is then
washed to remove sodium and sulfate ions, either with water or
a very weak acid solution. The resulting product is then dried
to a low moisture content, usually less than 25 percent by
weight, e.g., 10 percent to 20 percent by weight, to provide
the finished catalyst product.
The silica hydrogel slurry with or without alumina in hydrous
form may be filtered and washed in gel form to affect purifica-
tion of the gel by the removal of dissolved salts.
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1~371~2
This may enhance the formation of a continous phase in the
spray dried microspheric particles. If the slurry is prefil-
tered and washed and it is desired to spray dry the filter
cake, the latter may be reslurried with enough water to produce
a pumpable mixure for spray drying. The spray dried product
may then be washed again and given a final drying in the manner
previously described.
The metal additives to immobilize vanadia includes the metals,
their oxides and salts, or organo-metallic compounds of such
metals as Mg, Ca, Sr, Ba, Sc, Y, La, Ti, Zr, Hf, Nb, Ta, Mn,
Fe, In, Tl, Bi, T~, the rare eaths, and the actinide and
Lanthanide series of elements. These promoters or metal addi-
tives in the metal element state, may be used in concentration
ranges from about 0.5 to 20 percent, more preferably about 1 to
5 percent by weight of finished catalyst.
The catalytically active promoter in the preferred catalyst
composition is a crystalline aluminosilicate zeolite, commonly
known as molecular sieves. Molecular sieves are initially
formed as alkali metal aluminosilicates, which are dehydrated
forms of crystalline hydrous siliceous zeolites. However,
since the alkali form does not have appreciable activity and
alkali metal ions are deleterious to cracking processes, the
aluminosilicates are ion exchanged to replace sodium with some
other ion such as, for example, ammonium and/or rare earth
metal ions. The silica and alumina making up the structure of
the zeolite are arranged in a definite crystalline pattern
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~1~3792
containing a large number of small uniform cavities intercon-
nected by smaller uniform channels or pores. The effective
size of these pores is usually between about 4A and 12A,
The zeolites which can be employed in accordance with this
invention include both natural and synthetic zeolites. The
natural occurring zeolites include gmelinite, clinoptilolite,
chabazite, dec~iardite, faujasite, heulandite, erionite, anal-
cite, levynite, sodalite, cancrinite, nepheline, lcyurite,
scolicite, natrolite, offertite, mesolite, mordenite, brewster-
ite, ferrierite, and the like. Suitable synthetic zeolites
include zeolites Y, ~, L, ZK-4B, B, E, ~, H, J, M, Q, T, W, X,
Z, ZSM-types, alpha, beta and omega. The term "zeolites" as
used herein contemplates not only aluminosilicates but sub-
stances in which the aluminum is replaced by gallium and sub-
stances in which the silicon is replaced by germanium and also
the so called pillared clays more recently introduced.
The zeolite materials utilized in the preferred embodiments of
this invention are synthetic faujasites which possess silica to
alumina ratios inthe range from about 2.5 to 7.0, preferably
3.0 to 6.0 and most preferably 4.5 to ~0/ Synthetic fauja-
sites are widely known crystalline aluminosilicate ~eolites and
common examples of synthetic faujasites are the X and Y types
commercially available from the Davison Division W. R. Grace
and Company and the Linde ~ivision of Union Carbon Corporation.
The ultrastable hydrogen exchanged zeolites, such as Z-14XS and ~
Z-14US from Davison, are also particularly suitable. In addi-
tion to faujasites, other preferred types of zeolitic materials
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792
are mordenite and erionite.
The preferred synthetic faujasite is zeolite Y which may he
prepared as described in U. S Patent No 3,130,007 and U. S,
Patent No, 4,~10,116,
ref-erence. The aluminosilicates of this latter patent have
high silica (SiO2) to alumina (A12O3) molar ratios, preferably
above 4, to give high thermal stability.
The following is an example of a zeolite produced by the sili-
cation of clay. A reaction composition is produced from a mix-
ture of sodium silicate, sodium hydroxide, and sodium chloride
formulated to contain 5.27 mole percent SiO2, i 5 mole percent
Na2O, 1.7 mole percent chloride and the balance water. 12.6
parts of this solution are mixed with 1 part by weight of cal-
cined kaolin clay. The reaction mixture is held at about 60F ,~
to 75F for a period of about four days. After this low tem-
perature digestion step, the mixture is heated with live steam ;,
to about 190F until crystallization of the material is com-
plete, for example, about 72 hours. The crystalline material : ¦
is filtered and washed to give a silicated clay zeolite having -
a silica to alumina ratio of about 4.3 and containing about
about 13.5 percent by weight of Na2O on a volatile free basis.
Variation of the components and of the times and temperatures~
as is usual in commercial operatians, will produce zeolite hav-
ing silica to alumina mole ratios varying from about 4 to about
5. Mole ratios above 5 may be obtained by increasing the
amount of SiO2 in the reaction mixutre. The sodium form of the5 zeolite is then exchanged with polyvalent cations to reduce
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1~3~
the Na2O content to less than about 5 percent by weight, and
preferably less than 1.0 percent by weight. Procedures for
removing alkali metals and putting the zeolite in the proper
form are well-known in the art as described in a. s. Patent
~os. 3,293,192; 3,402,996; 3,446,727; 3,449,070; and 3,537,816;
The zeolites and/or the metal additive can be suitably
dispersed in matrix materials for use as cracking catalysts by
methods well-known in the art, such as those disclosed, for
example, in ~. S. Patent Nos. 3,140,249 and 3,140,253 to Plank,
et al.; U. S. Patent No. 3,660,274 to Blazek, et al.; U. S. ¦~
- 15 Patent No. 4,010,116 to Secor, et al.; U. S. Patent No;
3,944,482 to Mitchell, et al.; and U. S. Patent No. 4,079,019
to Scherzer, et al.;
!
The amount of zeolitic material dispersed in the matrix based
on the final fired product should be at least about 10 weight
percent, preferably in the range of about 25 to 50 weight per- ¦
cent, most preferably about 35 to 45 weight percent.
Crystalline aluminosilicate zeolites exhibit acidi~ sites on
both interior and exterior surface with the largest proportion
to total surface area and cracking sites being internal to the
particles within the crystalline micropores. These zeolites
are usually crystallized as regularly shaped, discreet parti-
cles of approximtely 0.1 to 10 microns in size and, according-
3~ ly, this is the size range normally provided by commercial
; - 32 -
, .
~A.
1~379Z
catalyst suppliers. To increase exterior (portal) sur~ace
area, the particle size of the zeolites for the present inven-
tion should preferably be in the range of less than 0.1 to 1
micron and more preferably in the range of less than 0.1
micron. The preferred zeolites are thermally stabilized with
hydrogen and/or rare earth ions and are steam stable to about
1,650F.
An example of the effectiveness of the metals of this invention
to immobili~e vanadium and reduce its destructiveness towards
the crystallinity of the zeolite structure is shown in Table 6.
A standard FCC catalyst was steamed with and without vanadia,
as shown in Run l and 2. The presence of vanadium reduces the
zeolite content from an intensity of 9.4 down to 3:1~ Runs 3
and 4 illustrate the effectiveness of titania and the need for
the titania to be present as the vanadia is being deposited on
the catalyst. As shown in runs 4, the titanium and vanadium
are deposited as organo-metallics, oxidized to remove th hydro-
carbon portion of the organo-metallic compound and oxidize the
elements to their corresponding oxides. This is then followed
by steaming at 1450F - 5 hrs. During the oxidation and steam-
ing, the titanium is present in at least a one to one ratio for
the formation of titanium vanadate which is a high melting
solid (see Ta~le A).
- 33 -
~1~379Z
TA3L _
St ing Performed at 1450F - 5 Hrs.
V as Vanadium Naphthenate
Ti as Tripropyltitanate
5Standard Catalyst V Ti Ti Zeolite
Run # ppm ppm Addition Intensity
1 0 0 - ~.4
2 5500 0 - 3.1
3 5500 5500 Ti added after 3.5
V regeneration
4 .55005500 Ti added with ~.2
V compound
Then
regenerated
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