Process for increasing the activity of zeolite containing particulate solids

A process for increasing the activity of a zeolite-containing particulate solid containing contaminants which block the pores of the zeolite and adversely affect the activity thereof wherein the contaminated zeolitic material is slurried with a liquid containing an acid, detergent or surfactant, the slurry is agitated to liberate the pore-blocking contaminants from the zeolite pores so that they are suspended in the liquid, a portion of the liquid is withdrawn from the slurry and filtered to remove the suspended contaminants, the resulting liquid is returned to the slurry, and the treated zeolite-containing particulate solid is liquid from the solution and recovered.

FIELD OF THE INVENTION 
This invention relates to a process for improving the activity of a 
particulate solid material containing a zeolitic material, and 
particularly to a process for reactivating a zeolite-containing 
hydrocarbon processing catalyst, such as those zeolitic catalysts known 
for use in fluid catalytic cracking, hydrocracking, alkylation, 
dealkylation, transalkylation, isomerization, polymerization, and 
separation processes. 
BACKGROUND OF THE INVENTION 
Zeolites are very common materials in nature and there are many types of 
synthetic zeolites. It is estimated that there are 34 species of zeolite 
minerals and about 100 types of synthetic zeolites. 
Zeolites are used in a wide range of chemical process technologies. The 
wide variety of applications includes separation and recovery of normal 
paraffin hydrocarbons, catalyst for hydrocarbon reactions, drying of 
refrigerants, separation of air components, carrying catalyst in the 
curing of plastics and rubber, recovering radioactive ions from 
radioactive waste solutions, removing carbon dioxide at high altitudes, 
solubilizing enzymes, separating hydrogen isotopes, and removal of 
atmospheric pollutants such as sulfur dioxide. Cracking catalysts, such as 
those used in fluid catalytic cracking (FCC) and hydrocracking of 
hydrocarbon fractions, contain crystalline zeolites, often referred to as 
molecular sieves, and are now used in almost 100% of the FCC units, which 
process about 10 million barrels of oil per day. 
Zeolites, or molecular sieves, have pores of uniform size, typically 
ranging from 3 to 10 angstroms, which are uniquely determined by the unit 
structure of the crystal. These pores will completely exclude molecules 
which are larger than the pore diameter. As formed in nature or 
synthesized, zeolites are crystalline, hydrated aluminosilicates of the 
Group I and Group II elements, in particular, sodium, potassium, 
magnesium, calcium, strontium, and barium, which can be exchanged with 
higher polyvalent ions, such as rare earths or with hydrogen. 
Structurally, the zeolites are "framework" aluminosilicates which are 
based on an infinitely extending three-dimensional network of AlO.sub.4 
and SiO.sub.4 tetrahedra linked to each other by sharing all of the 
oxygens. Zeolites may be represented by the empirical formula: 
EQU M.sub.2/n O.multidot.Al.sub.2 O.sub.3 .multidot.xSiO.sub.2 
.multidot.yH.sub.2 O 
In this oxide formula, x is generally equal to or greater than 2 since 
AlO.sub.4 tetrahedra are joined only to SiO.sub.4 tetrahedra, n is the 
cation valence. The framework contains channels and interconnected voids 
which are occupied by the cation and water molecules. The cations are 
quite mobile and may be exchanged, to varying degrees, by other cations. 
Intercrystalline "zeolitic" water in many zeolites is removed continuously 
and reversibly. In many other zeolites, mineral and synthetic cation 
exchange or dehydration may produce structural changes in the framework. 
As stated above, the uses for zeolites are many, but they typically must be 
combined with other materials when they are used in process applications. 
As an example, a synthesized zeolitic material, which is usually less than 
4 microns in size, is combined with a binding agent, such as kaolin clay, 
silica sol, or amorphous silica, alumina, and zirconia as described in 
Demmel's U.S. Pat. No. 4,826,793 and then spray dried or extruded to 
produce a finished material that has the properties desired for the 
intended use. These properties may include attrition resistance, crush 
strength, particle size distribution, surface area, matrix area, activity 
and stability. Another method of producing a finished zeolite containing 
product would be to produce the zeolite in-situ as described in Hayden's 
U.S. Pat. No. 3,647,718. While these patents deal mainly with FCC type 
catalyst, similar procedures are used in the production of zeolitic 
materials for other process applications. As an example, most fixed bed 
zeolytic catalyst, such as those used in hydrocracking, alkylation, 
dealkylation, transalkylation, isomerization, polymerization, and 
separation processes, disperse the zeolytic component in a pellet that 
consists mainly of alumina. Based on our discovery it is our belief that 
in the manufacture of these fixed bed pelleted zeolitic catalyst and 
zeolitic FCC type catalyst that some of the zeolitic pores are blocked or 
buried within the matrix material and that our process can remove this 
blockage and increase the available zeolite. So not only is our process 
applicable to spent or equilibrium catalyst, but also to fresh catalyst. 
An objective in refining crude petroleum oil has always been to produce 
maximum quantities of the highest value added products in order to improve 
the profitability of the refining. Except for specialty products with 
limited markets, the highest value added products of oil refining with the 
largest market have been transportation fuels, such as gasoline, jet fuel 
and diesel fuels. Historically, a major problem in the refining of crude 
oil has been to maximize the production of transportation fuels. This 
requires a refining process or method which can economically convert the 
heavy residual oil, the crude oil fraction boiling above about 
1000.degree. F., into the lighter boiling range transportation fuels. A 
major obstacle to the processing of this heavy residual oil has been the 
concentration of refining catalyst poisons, such as metals, nitrogen, 
sulfur, and asphaltenes (coke precursors), in this portion of the crude 
oil. 
Since most of the oil refineries in the world use the well known fluid 
catalytic cracking (FCC) process as the major process for the upgrading of 
heavy gas oils to transportation fuels, it is only natural that the FCC 
process should be considered for use in the processing of heavy residual 
oils. Indeed, this has been the case for the last ten to fifteen years. 
However, the amount of residual oil that a refiner has been able to 
economically convert in the FCC process has been limited by the cost of 
replacement catalyst required as a result of catalyst deactivation which 
results from the metals in the feedstock. The buildup of other catalyst 
poisons on the catalyst, such as the coke precursors, nitrogen and sulfur, 
can be effectively controlled by using catalyst coolers to negate the 
effect of coke formation from the asphaltene compounds, using regenerator 
flue gas treating to negate the environmental effects of feed sulfur, and 
using a short contact time FCC process, such as that described in U.S. 
Pat. No. 4,985,136, to negate the effects of feed nitrogen, and to some 
degree, the feed metals. 
For the past twenty or more years the most widely used FCC catalysts have 
been zeolitic catalysts, which are finely divided particles formed of a 
relatively inert matrix, usually silica-alumina, alumina or the like, 
having a highly active zeolitic material dispersed in the matrix. As is 
well-known, the zeolites used in such catalysts are crystalline and 
typically have a structure of interconnecting pores having a pore size 
selected to permit the ingress of the hydrocarbon molecules to be 
converted, and the zeolite has a very high cracking activity. Therefore, 
the highly active zeolite is dispersed in a matrix having a lesser 
cracking activity in a ratio providing the desired activity for commercial 
use. Typically used zeolites are of the faujasitic type, e.g., X-, Y- or 
L-type synthetic zeolites, and from about 5 wt. % to about 70 wt. % of the 
zeolite is employed. Such zeolitic FCC catalysts, their manufacture and 
their use in the FCC process are well known by those working in the art. 
It is commonly accepted in the oil refining industry that vanadium 
contained in the residual oil FCC feedstock will irreversibly deactivate 
the zeolite by attacking the structure, and that this vanadium effect is 
more pronounced at temperatures above about 1330.degree. F. It is also 
commonly accepted that catalyst deactivation by hydrothermal deactivation 
or by metals (e.g., sodium and vanadium) attack is irreversible. 
In the operation of an FCC process unit (FCU) the process economics are 
highly dependant upon the replacement rate of the circulating catalyst 
(equilibrium catalyst) with fresh catalyst. Equilibrium catalyst is FCC 
catalyst which has been circulated in the FCC between the reactor and 
regenerator over a number of cycles. The amount of fresh catalyst addition 
required, or the catalyst replacement rate, is determined by the catalyst 
loss rate and that rate necessary to maintain the desired equilibrium 
catalyst activity and selectivity to produce the optimum yield structure. 
In the case of operations wherein a feedstock containing residual oil is 
employed, it is also necessary to add sufficient replacement catalyst to 
maintain the metals level on the circulating catalyst at a level below 
which the FCC yield structure is still economically viable. In many cases, 
low metal equilibrium catalyst with good activity is added along with 
fresh catalyst to maintain the proper FCC catalyst balance at the lowest 
cost. 
In the processing applications that utilize zeolites, the material must be 
replaced as it looses its ability to perform the desired function. That 
is, the zeolitic material deactivates under the conditions employed in the 
process. In some cases, such as FCC and TCC type catalytic applications, 
fresh zeolitic material, in this case zeolitic catalyst or additives such 
as ZSM-5 (described in U.S. Pat. No. 3,703,886), are added on a daily 
basis. Fresh zeolitic catalyst is added daily at a typical rate of from 1% 
to as high as 10% of the process unit inventory to maintain the desired 
activity in the plant. Other zeolitic catalysts, such as those used in 
hydrocracking, alkylation, dealkylation, transalkylation, isomerization, 
polymerization, and separation processes, are usually replaced as a batch 
when the zeolitic material deactivates to a certain point, at which the 
plant is shutdown and the zeolite replaced. 
As will be seen from the following discussion, it is our belief that many 
types of zeolitic catalyst can benefit from the present invention, 
because, contrary to popular belief, the major cause of zeolitic catalyst 
activity decline is zeolite pore blockage which can occur, even during the 
catalyst manufacturing process, due to free silica or alumina, or 
compounds of silica or alumina, or other materials which are left behind 
and block the zeolite pore openings. 
A primary object of the present invention is to enable the removal of 
zeolitic catalyst deactivating materials without destroying the integrity 
of the catalyst and, at the same time, to significantly improve the 
activity and selectivity of the catalyst. Another object of the present 
process is to reactivate zeolite-containing equilibrium catalyst using an 
environmentally safe and acceptable process. Still another object of the 
present invention is to improve the activity of various types of zeolitic 
catalyst and other zeolite-containing particulate solids, especially those 
that deactivate during use in the processing of hydrocarbons. 
A further object of the present invention is improve the FCC equilibrium 
catalyst activity and selectivity. Another object of this invention is to 
improve the activity of fresh zeolitic catalyst. Still another objective 
of the invention is to reduce the requirement for fresh catalyst 
replacement to an FCC unit, which will reduce fresh catalyst costs, 
transportation costs, equilibrium catalyst disposal costs, and unit 
catalyst losses. Other objects of the invention will become apparent from 
the following description and/or practice of the invention. 
SUMMARY OF THE PRESENT INVENTION 
The above objects and other advantages of the present invention may be 
achieved by a process for improving the activity of a contaminated 
zeolite-containing particulate solid containing one or more contaminants 
which block the pores of the zeolite and adversely affect the activity of 
the solid, which process comprises treating the solid by 
a. forming a slurry of the particulate solid with an aqueous solution 
containing an activating agent selected from the group consisting of 
acids, detergents and surfactants, the agent being effective to solubilize 
or dislodge the contaminants; 
b. agitating the slurry under activation conditions including a temperature 
and a time sufficient to solubilize or dislodge the contaminants, so that 
the resulting solubilized or dislodged contaminants are carried by the 
solution from the particulate solid; 
c. withdrawing from the slurry a portion of the solution containing the 
solubilized or dislodged containments; 
d. separating the resulting particulate solid from the solution remaining 
in the slurry; 
e. washing the separated particulate solid to remove any residual solution; 
and 
f. recovering a treated zeolite-containing particulate solid having a level 
of activity greater than the activity of the contaminated solid. 
We now have discovered that much of the deactivation mechanism for zeolitic 
materials results from zeolitic pore blockage, which can be reversed. This 
pore blockage can occur during the production stage by the retention of 
silica or other binding or matrix material in the zeolite pores. The pore 
blockage can also occur during the processing stage by silica that 
migrates to the pores, hydrocarbons from the feed or reaction products, or 
other materials present in the feed, or catalyst itself, that deposit or 
migrate into the zeolite pores, thereby blocking off access and reducing 
the activity of the zeolite. We have indications that hydrocarbon material 
may help to bind the silica and other feed and matrix material in the 
pores of the zeolite, or only hydrocarbon material may block the pore. 
This blockage prevents the reactants from entering the zeolite pores and 
therefore reduces the activity of the zeolite. Another cause of zeolite 
deactivation is the dehydration of the zeolitic structure. 
We have found that there are various methods for reactivating these 
zeolitic materials based on (1) chemical treatments, which loosen or 
solubilize the materials blocking the zeolite pores, and (2) agitation, 
which aids in mechanically removing the pore blockage material. We have 
also found that these two steps alone will not satisfactorily reactivate 
the zeolite unless the material removed from the pores is separated from 
the reactivated product. For example, we have learned through 
experimentation that, if one filters the total solution to separate the 
liquid from the solid without first separating the small particle size 
material and hydrocarbon material that has caused the pore blockage, the 
small particles and hydrocarbon material may redeposit in the pores of the 
zeolite. This redistribution of the small particles and hydrocarbon may 
again block off pores and reduce the activity of the zeolite. This also 
happens in fresh catalyst manufacture. Especially in those manufacturing 
processes that use slurry, the process can be modified to include a 
separation step that removes these small sized particles, so that the 
final product would be increased/improved. As an example, if the exchange 
of rare earth elements in FCC catalyst manufacture is accomplished in a 
agitated slurry system, it is possible that the activity of the final 
product may be reduced because of the redistribution of the material 
removed from the zeolitic pores in the chemical/agitation stage. On the 
other hand, if these pore blocking materials were removed from the 
solution prior to filtering, the activity of the final product would be 
increased. 
We have now discovered that, in accordance with the present invention, in 
order to most satisfactorily reactivate the zeolite, it is desirable to 
separate the pore blocking materials that block the zeolitic pores from 
the zeolite being reactivated. Such separation allows one to obtain 
consistent results in a process for improving the activity of zeolitic 
materials, either during their manufacture or during reactivation. 
We have tried a member of chemical methods of reactivating zeolitic 
materials and they all have increased the zeolitic activity when the 
chemical treatment was combined with both the agitation of the solid 
zeolite material in a chemical solution containing an activating agent and 
separation of the small (&lt;10 microns) pore blocking material that is 
removed from the zeolitic pores by the chemical treatment and agitation. 
The same chemical treatment without agitation and separation was found not 
to greatly improve the zeolitic activity. 
The chemical treatment is normally carried out at between 3 and 7 pH and at 
a temperature less than 212.degree. F. The chemical treatment has been 
accomplished with activating agents such as enzymes containing 
degreasing/surfactants, malic acid, active fluorides, hydroxylamine 
hydrochloride, and other acidic materials, as well as detergents. One can 
raise the temperature above 212.degree. F. to help obtain agitation by 
boiling, but then one must provide for fresh liquid makeup and recovery of 
the vapors. Another option, if higher temperature is proven desirable, is 
to conduct the operation under pressure, which is more costly. 
The agitation can be by stirring, aeration, or tumbling. The preferred 
method for small particle size materials, such as FCC type catalyst, is to 
form a slurry of up to 75% concentration of solids and to keep the 
particulate solid suspended in the solution and also keep the maximum 
surface area of the solid exposed to the fresh chemical reaction by 
stirring, and aeration. For larger particle size zeolitic materials, which 
would include hydrocracking catalyst, polymerization catalyst, ZSM-5 
catalyst, and molecular sieves, stirring may not be as practical as just 
pumping around the liquid in the contacting vessel so that it flows upward 
through the bed of pellets/extrudates along with the aeration media. The 
liquid pumparound may be removed below the upper liquid level and returned 
to the bottom of the contacting vessel to provide a mixing of the chemical 
liquid in the contactor and an upward flow of liquid with the aeration 
media to aid in agitation and stripping of the small particles from the 
zeolile pores. In either case, the small particles liberated from the 
zeolitic pores may be removed from the slurry continuously or at the end 
of the reactivation cycle by known particle separation processes, such as 
flocculation, flotation, elutriation, and clarification, with the 
preferred method being continuous flotation (defined as: a process whereby 
the grains of one or more minerals, or chemical compounds in a pulp or 
slurry, are selectively caused to rise to the surface in a cell or tank by 
the action of bubbles of air, wherein the grains are caught in a froth 
formed on the surface of the tank and are removed with the froth, while 
the grains that do not rise remain in the slurry and are drawn off the 
bottom of the cell or tank), or a combination of flotation with 
flocculation or elutriation. 
The time of treatment can be varied from several minutes to many hours 
depending on the temperature, chemical concentration, percent solids, 
particle size of the zeolite material, and the nature of the material 
blocking the pores. We have found that the chemical activating agent acts 
to dissolve and/or loosen the pore blockage material, while the 
aeration/stirring helps to separate the small particles that have been 
blocking the pores from the now reactivated material. The addition of 
surfactants and detergents to aid in the separation of the small particles 
by flotation or flocculation has also proved beneficial.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Since one of the largest markets for zeolites is in the manufacture of FCC 
catalyst, the following process description refers to the reactivation of 
regenerated FCC catalyst. However, the present invention is applicable to 
any fresh, spent, deactivated or equilibrium zeolitic containing material. 
It is only necessary that the surface of the zeolite material be free of 
coke; that is the coke should be removed by regeneration e.g., contacting 
spent catalyst with an oxygen-continuing gas at elevated temperature to 
burn the coke from the catalyst. 
The present invention comprises treating zeolite-containing materials in an 
agitated slurry solution containing a chemical activating agent which has 
been chosen to loosen or solubilize the materials blocking the zeolite 
pores, and separating the treated zeolite material from the small particle 
size materials removed by chemical treatment/agitation from the zeolite 
pores and the surface of the material before the treated zeolite material 
is separated from the liquid slurry. This liquid chemical treatment to 
remove the small particles from the pores of the zeolite can be 
accomplished in conjunction with other processing steps, such as, chemical 
removal of metals (Ni, V, Na, Mo, Co, Fe, etc) from equilibrium FCC 
catalyst or spent hydrocracking catalyst, or exchange of the zeolite with 
rare earth elements or other cations to modify the activity or selectivity 
of the zeolite. 
The first processing stage is to put the pore blocking material into 
solution or to loosen the small particles blocking the pores. This may be 
accomplished by treatment of the zeolite-containing solid particles in an 
agitated solution containing, as the activating agent, an acid or mixture 
of acids, followed by a wash treatment to remove the contaminates from the 
treated catalyst. In the preferred processing method, the agitation of the 
acid solution is accomplished by both stirring and aeration. It has been 
found that use of a combination of acids for treatment is more effective, 
and this is the preferred method. 
In applications, such as the treatment of spent hydrocracking catalyst that 
is oil soaked when it is removed from the hydrocracking reactor, the 
catalyst preferably is treated to remove the hydrocarbon surface layer, 
which will interfere with the efficiency of the present process. Normally, 
these types of spent fixed bed catalyst are regenerated under controlled 
conditions to remove the hydrocarbon/carbon layer before being treated in 
our process. 
As will be evident from the following example, the mechanism of catalyst 
reactivation is contrary to the beliefs of those working in the catalyst 
art. The results of the present invention indicate that the method of 
catalyst deactivation may be contrary to the accepted theory of 
irreversible zeolite structure collapse resulting from hydrothermal 
conditions or metals, such as sodium and vanadium, attack. The results of 
our testing indicate that the method of catalyst deactivation is 
reversible. While we may not know the precise method of catalyst 
deactivation, the results of our testing lead us to theorize that the 
primary method of catalyst deactivation is zeolitic pore blockage. This 
blockage is believed to result from the combination of feed components, 
such as heavy organic compounds, organometallic compounds or 
polymerization of zeolitic reaction products in the zeolite cage, and/or 
catalyst base materials, such as alumina and silica compounds. 
The preferred acids for use in the invention are weak acids, such as malic, 
acetic and ammonium bifluoride. For example, malic and may be used to keep 
the pH at 3.0 or above to minimize the removal or attack on the alumina in 
the catalyst structure. However, we believe the malic acid acts to loosen 
the material blocking the pores of the zeolite but is not strong enough to 
cause noticeable structural changes in the catalyst. The ammonium 
bifluoride, we believe, also helps to loosen the pore blockage material, 
which appears to be rich in silica. One can use other fluorides to react 
with the silica, but very active fluorides such as HF are not recommended 
because of their environmental/safety concerns and their tendency to 
remove structural silica. Normally the amount of ammonium bifluoride added 
to the solution will be less than 10 wt % of the catalyst being 
reactivated and typically between 1 and 4 wt %. The malic acid will be 
normally less than 15 wt % of the catalyst being treated and typically 
between 5 and 10 wt %. As will be seen in one of the examples below, we 
also used an enzyme, which contained both a detergent and a surfactant, 
and malic acid to reactivate an equilibrium FCC catalyst. In this case, 
the aeration media used caused a froth that separated the fine particles 
from the reactivated catalyst. The preferred enzymatic material contains 
both a surfactant and detergent which attacks the hydrocarbon binding or 
blocking agent so that the pore-blocking material in the zeolite cage can 
be removed and thereby reactivate the zeolite. The acid solubilizes, and 
the stirring/aeration agitation media combines with the surfactant in the 
enzymatic material to lift the small particles removed from the zeolite 
pores to the surface of the solution where they can be removed. The 
removal of these fine inorganic particles or hydrocarbon materials from 
the zeolite cage will open the zeolitic channels so that the interior of 
the zeolite is accessible to the vapor reactants; thereby reactivating the 
catalyst. It is also believed that the activity of fresh FCC zeolitic 
catalyst may be increased by this type treatment to remove any free 
alumina or silica compounds that might be retained in the pores of the 
zeolite during manufacture. This would also be the case for any fresh or 
equilibrium catalyst containing zeolites, such as zeolitic hydrotreating 
or hydrocracking catalyst, ZSM-5, zeolitic polymerization catalyst or 
molecular sieves. 
The results of our testing indicate that agitation with air, as well as 
dispersion of the solid in the solution by stirring, is also highly 
desirable. It is theorized that finely dispersed bubble agitation of the 
solids is advantageous in removing the obstructions from the zeolite 
pores. 
The following Example demonstrates the advantages of the present process 
when used to reactivate a commercial FCC catalyst formed of a 
silica-alumina matrix containing about 10-20 wt. % of a type Y zeolite. 
EXAMPLE A 
A sample of 50 gms of regenerated equilibrium FCC catalyst was placed into 
a solution of 200 ml of deionized water, 20 gms malic acid and 1 ml of a 
commercial enzyme and heated to about 130.degree. F. in a magnetically 
stirred beaker for 12 hours. During this time the solution was aerated 
with compressed air. The combination of the aeration and detergent in 
enzyme caused a froth phase to develop on the top of the liquid level. The 
aeration and froth combined to separate the small particles from the 
reactivated material and conveyed these small particles upward to the 
beaker top where they were skimmed off. After 12 hours the treated 
catalyst was filtered and washed to remove any remaining liquid and 
contaminants. The equilibrium catalyst (before treatment) and the 
reactivated catalyst (after treatment) were each tested on a Micro 
Activity Testing (MAT) unit at a 3:1 catalyst to oil ratio, 16 WHSV, 960F 
using a standard gas oil. The fresh catalyst activity and the analytical 
results for the untreated starting catalyst and the treated catalyst are 
detailed below: (two numbers indicate two tests) 
______________________________________ 
BEFORE AFTER 
TREATMENT TREATMENT 
______________________________________ 
FRESH ACTIVITY 2.8 
CATALYST ACTIVITY 
1.4 1.4 2.3 1.9 
MICRO ACTIVITY TEST: 
CONVERSION 59 59 70 66 
COKE FACTOR 1.8 3.1 1.4 1.7 
GAS FACTOR 12.1 5.3 2.2 4.9 
______________________________________ 
After extensive laboratory testing on zeolite reactivation to determine the 
proper procedure, five samples of equilibrium catalyst were obtained from 
five different operating FCC units. Each of these five equilibrium 
catalyst samples were more than likely mixtures of different types of 
fresh catalyst from different suppliers, since most FCC units change the 
type of fresh catalyst they add and also add outside equilibrium catalyst 
on occasion. However, it is known that these five equilibrium catalyst 
have a very broad range of activities and metals levels (Ni/V) since these 
units operate on feeds which go from gas oil to residual oil operations. 
However, the fresh catalyst added to these units would typically have 
20-30% of a Y or USY zeolite with different degrees of active matrix. All 
of the five samples were treated in the following manner: 
1. Regenerated the as received equilibrium catalyst in a muffle furnace at 
1250.degree. F. for 4 hours using an oxygen-containing gas. 
2. Added 100 gms of the regenerated equilibrium to 500 cc of deionized 
water. 
3. Added 4 gms of hydroxylamine so that pH was between 3.8 and 4.0 at 
71.degree. F. The hydroxylamine is used as a reducing agent, mainly to 
reduce the nickel on the catalyst. 
4. Sample from step 3 was placed on magnetic stirrer-hot plate. At 
125.degree. F. added 2 gms ammonium bifluoride and 10 gms malic acid (pH 
of 3.0) and raised temperature to about 150.degree. F. 
5. After 2 hours at between 125.degree. F. and 150.degree. F., removed 
sample from stirrer-hot plate, and allowed the sample to settle until the 
majority of catalytic material was out of suspension but the fine particle 
size and colloidal material was still in solution, and decanted the sample 
to remove the fine particles that were still in solution. 
6. Washed the decanted sample 3.times.with 300 ml of deionized water and 
decanted after each wash as described in 5 above. Samples of each of the 
five reactivated equilibrium samples was tested and the results are shown 
below. 
7. 40 gms of each of the five washed reactivated samples from step 6 were 
exchanged with 3.64 gms of a rare earth element solution (27.46% rare 
earth element oxides consisting of 12.23% La.sub.2 O.sub.3, 7.22% 
CeO.sub.2, 5.64% Nd.sub.2 O.sub.3, 1.95% Pr.sub.6 O.sub.4) in 100 cc of 
deionized water. After two hours at 190.degree. F., the now rare earth 
exchanged reactivated samples were washed 2.times.with 150 cc deionized 
water and dried overnight in a drying oven and put in the muffle furnace 
for 1 hour at 1000.degree. F. 
8. The regenerated equilibrium catalyst, the reactivated samples from step 
6 and the rare earth exchanged samples from step 7 were tested as detailed 
below. 
The testing was done on a Micro Activity Testing (MAT) unit at a 3:1 
catalyst to oil ratio, 16 WHSV, 960F using a standard gas oil. Samples A 
and C were equilibrium catalyst from FCCU's operating on residual oil. The 
results of the MAT testing indicated the following: 
______________________________________ 
MAT TEST RESULTS 
SAMPLE ACTIVITY COKE FACTOR GAS FACTOR 
______________________________________ 
A REGENERATED 0.75 7.63 2.04 
EQUILIBRIUM 
A REACTIVATED 1.16 4.36 1.33 
A RARE EARTH 1.34 4.29 1.01 
EXCHANGED 
B REGENERATED 1.23 2.28 1.58 
EQUILIBRIUM 
B REACTIVATED 1.56 2.23 1.53 
B RARE EARTH 1.72 2.32 1.69 
EXCHANGED 
C REGENERATED 1.02 4.71 1.50 
EQUILIBRIUM 
C REACTIVATED 1.25 4.39 1.12 
C RARE EARTH 1.56 3.75 0.97 
EXCHANGED 
D REGENERATED 1.36 3.89 1.33 
EQUILIBRIUM 
D REACTIVATED 2.06 3.01 1.14 
D RARE EARTH 1.70 3.91 1.45 
EXCHANGED 
E REGENERATED 1.01 1.52 1.21 
EQUILIBRIUM 
E REACTIVATED 1.29 2.48 1.07 
E RARE EARTH 1.20 3.29 1.17 
EXCHANGED 
______________________________________ 
The MAT results above not only show an increase in activity for all of the 
reactivated samples, but also indicate a selectivity improvement in the 
reactivated catalyst as compared to the regenerated equilibrium. Samples 
A, B, and C indicate that there was available zeolite that exchanged with 
the rare earth elements, which resulted in increased activity and 
selectivity. Based upon these results, we believe that the mechanism for 
zeolytic catalyst reactivation is the removal of small particle size 
material from the zeolytic pores. An analysis of this material indicated 
it is rich in silica along with the other components of the catalyst 
including alumina, nickel, and vanadium. We theorize that the pore 
blockage material is deposited in the pores of the zeolite during the 
manufacture of the fresh catalyst and by the migration of silica during 
operation of the processing unit. 
The above data indicates that contrary to popular belief, the activity and 
the selectivity of regenerated FCC catalyst can be greatly improved. 
Therefore, by practice of the present invention one can remove what is 
commonly referred to as equilibrium zeolitic catalyst from the processing 
unit, treat the catalyst as disclosed herein and reuse the treated 
catalyst having an improved activity and selectivity. 
As can be seen from these examples, we believe that the key to a successful 
zeolitic catalyst reactivation process is removing the zeolitic pore 
blockage material from the pores of the zeolite and separating this 
material from the reactivated zeolitic catalyst. The examples indicate 
that the material blocking the pores can be loosened by mild acids or 
combinations of acids that are reactive with the pore blockage material 
and that the best method of separating the fine particles removed from the 
zeolytic pores is by flotation. The laboratory data also indicates that a 
mixture of mild acids such as ammonium bifluoride and malic acid at pH of 
3 to 5 takes less time than malic acid on its own. 
ZEOLITIC CATALYST REACTIVATION PROCESS 
In a commercial operation using the zeolitic catalyst reactivation process 
of the present invention an essentially carbon free catalyst is mixed with 
a chemical solution containing the activating agent in an agitated 
contactor vessel to form a slurry. There is withdrawn from the top of the 
liquid level a portion of the chemical solution which contains the 
majority of the suspended fine particles and solids liberated from the 
zeolite pores. This withdrawn solution and fine particles is filtered to 
remove the suspended solids, and the filtered liquid is returned to the 
contactor vessel. After a period of time at the desired temperature, the 
treated, reactivated zeolite is separated from the chemical solution and 
washed to remove as much as possible of any remaining chemical solution so 
that the reactivated zeolitic material can be reused. 
A commercial FCC catalyst reactivation process would comprise contacting a 
regenerated catalyst in an stirred and air agitated chemical solution 
containing an activating agent, that consists of a mild acid, such as 
malic, or a mixture of mild acids such as malic and ammonium bifluoride, 
in a contacting vessel. There is continuously withdrawn from the top of 
the liquid level in the contactor a portion of the chemical solution which 
contains a majority of the suspended fine particles liberated from the 
zeolite pores. This liquid is filtered to remove the fine particles and 
the filtrate recycled to the contactor vessel. After a period of time at 
the desired temperature, the treated activated FCC catalyst is separated 
from the chemical solution and washed to remove as much as possible of any 
remaining chemical solution so that the reactivated FCC catalyst can be 
reused. Since the FCC catalyst is of small particle size, a stirred 
catalyst slurry contactor is preferred. Any hydrocarbon released from the 
zeolitic pores can also be removed from the top of the liquid level in the 
contactor before the treated, reactivated catalyst is separated from the 
chemical solution. 
Large sized zeolitic materials, such as pelleted or extruded zeolitic 
catalyst, can also be treated in stirred vessels. However, other forms of 
agitation, such as tumbling or ebulating beds, or only recirculation of 
the chemical solution to the bottom of the vessel to give a continuous 
upward flow of chemical in conjunction with the aeration media can also be 
used if desired. 
The preferred aeration media in any embodiment of the present reactivation 
process is air, but other gases, such as nitrogen or light hydrocarbon 
gases, which will act as a flotation media for the small particles of &lt;10 
micron may be used. 
The present invention can be integrated with an FCC process unit, or the 
equilibrium catalyst and additives can be withdrawn from the regenerator, 
cooled, placed in storage and then shipped to a reactivation process to be 
reactivated and returned to the original site for addition to the FCC 
process. Based on economics and the ease of integration of the present 
unique reactivation process with the FCC process, the preferred location 
of the reactivation process would be in conjunction with the FCC process 
and not at a remote location. 
FIG. 1 illustrates a preferred process flow for the practice of the present 
invention. Those skilled in the art may know of other equipment which may 
be employed in the process. It is important, however, that the equipment 
selected perform the functions described herein so that the desired 
reactions and results are obtained. In the preferred batch process 
diagrammed in FIG. 1, the desired weight of regenerated zeolitic FCC 
catalyst flows from storage hopper 1 by gravity flow, utilizing load cell 
2 and control valve 3, into contactor 4 to form a slurry with liquid in 
the contactor. The liquid in the contactor is water containing the desired 
amounts of mild acids, which are effective to dislodge and/or solubulize 
the pore-blocking contaminants in the zeolite pores. Contactor 4 is 
agitated by mechanical stirrer 5 and air from line 6, which is injected 
into the bottom of the liquid through air distribution grid 7. Malic acid 
or a mixture of malic and ammonium bifluoride from storage hopper 10 is 
added into contactor 4 on weight control using load cell 8 and control 
valve 9 to control the pH at between 3 and 7, with a pH of about 5.2 being 
preferred. A surfactant/detergent from storage tank 11 is added on weigh 
control utilizing load cell 12 through control valve 13 into contactor 4 
to control the surfactant/detergent concentration within a suitable range 
which may be from about 1 ppm to 10 wt %, depending upon the catalyst and 
conditions employed in the contactor. Such a surfactant and/or detergent 
forms a foam to aid in floating the small contaminant particles at the top 
of the liquid in the contactor. Use of the surfactant/detergent along with 
the contactor agitation will result in the formation of a foam on the top 
of the liquid level in the contactor as long as there is sufficient active 
surfactant/detergent in the chemical solution. Therefore, if at any time 
during this batch process the foam disappears then more 
surfactant/detergent can be added to restore the surfactant/detergent 
action which aids in the removal by floatation of the small contaminant 
particles liberated from the zeolitic pores. Contactor 4 can be operated 
at ambient temperature, but it is preferred to operate at from about 
130.degree. F. to 200.degree. F., but in no case at a temperature that 
will kill the surfactant/detergent activity. The temperature in contactor 
4 can be controlled by an external heat source, such as, a steam coil or 
jacket on the vessel. Depending on the type of zeolitic material being 
treated and the chemicals and temperature employed in the processing, the 
treatment time can be as low as 10 minutes and as long as 36 hours, with 4 
to 12 hours being normal. 
The aeration supply can be, as shown in FIG. 1, a closed circuit system 
utilizing compressor 6a to take gas from the top of contactor 4 and 
recycle it back to the bottom of contactor 4 through distribution grid 7, 
or it can be a once through system with the aeration media vented from 
contactor 4. 
Contactor 4 is equipped with a sidedraw 14 that controls the level in the 
contactor. From sidedraw 14, a continuous flow of liquid solution, which 
contains the small particles which were removed from the zeolite in 
suspension, is taken through pump 15 to filter 16. The filter shown in 
FIG. 1, is a plate and frame filter, but any filter that will remove &lt;10 
micron particles from the circulating liquid could be used. The filtered 
liquid is returned to the bottom of contactor 4, where it will flow upward 
along with the aeration media and aid in removing the small solid 
particles which are to be liberated from the zeolite pores by the agitated 
solution containing the activating agent. 
After the reactivation process is complete, the aeration media and liquid 
recycle through the filter is stopped. Before the slurry solution is 
drained from the bottom of contactor 4, any hydrocarbon that has 
accumulated on the top of the liquid level can be removed by draining from 
the sidedraw. The reactivated zeolite and solution are separated, 
preferably on a belt filter (not shown) and the reactivated catalyst is 
washed to remove any remaining solution. If necessary, this reactivated 
material can be dried. 
Our testing has indicated that the efficiency of this reactivation process 
can be improved by the addition of a suitable concentration of ammonium 
bifluoride to the activating liquid to aid in the removal of free silica 
from the pores of the zeolite. 
Having described a preferred embodiment of our invention, it is to be 
understood that variations and modifications thereof falling within the 
spirit of the invention may become apparent to those skilled in this art, 
and the scope of the invention is to be determined by the appended claims 
and their equivalents.