Superparamagnetic formation of FCC catalyst provides means of separation of old equilibrium fluid cracking catalyst

Improved catalytic process for carrying out heavy hydrocarbon conversion in the presence of metal on the catalyst and in the feedstock, by catalytic cracking such heavy carbometallic oils to lighter molecular weight fractions. The discovery of a ferro/superparamagnetic component of older catalyst, which when present, can be employed to achieve enhanced magnetic separation of aged catalyst. This invention utilizes this property to enhance separation of more magnetically active, older, less catalytically active and selective, higher metals-containing catalyst particulates from less magnetically active, lower metal containing particulates. The more catalytically active and selective catalysts fractions, are then recycled back to the process.

RERMS 
Subsequent work has developed a preferred method of separation involving 
the use of a magnetic rare earth roller device (RERMS) and a pending 
application U.S. Ser. No. 07/332,079 filed Apr. 3, 1989, abandoned, covers 
the concept of using such a device for magnetic separation. 
In attempting to further improve separation, it has now been discovered 
that in the presence of larger amounts of paramagnetic iron, further 
improvement in separation selectivity can be realized and a pending 
application U.S. Ser. No. 07/479,003 filed Feb. 9, 1990 now U.S. Pat. No. 
5,106,486, covers the concept of a "Magnetic Hook".TM., and the use of 
continuous addition of iron to enhance separation. 
BACKGROUND OF INVENTION 
I. Field of the Invention 
The present invention relates to separation of hydrocarbon and other 
catalysts and sorbents by magnetic separation, generally classified in 
Class 55; Subclass 3; and Class 120, Subclasses 119+ of the U.S. Patent 
and Trademark Office. 
In fluid bed cracking of hydrocarbon feedstocks, it is the practice, 
because of the rapid loss in catalyst activity and selectivity, to 
continuously add fresh catalyst regularly, usually daily, to an 
equilibrium mixture of catalyst particles. These small microspherical 
particles vary in size from 10 to 150 microns and represent a highly 
dispersed mixture of catalyst particles. Some have been present in the 
unit for as little as one day, while others have been there for as long as 
60-90 days or more. Because these particles are so small, no process has 
been available to remove old catalysts from new, therefore, it usually is 
customary to withdraw 1 to 10% or more of equilibrium catalyst which 
contains all of these variously aged particles just prior to addition of 
fresh catalyst particles, thus providing room for the incoming fresh 
material. Unfortunately, the 1 to 10% of equilibrium catalyst withdrawn 
contains 1-10% of the very expensive catalyst added the day before, 1-10% 
of the catalyst added 2 days ago, 1-10% of the catalyst added 3 days ago, 
and so forth. Therefore unfortunately, a large proportion of withdrawn 
catalyst represents still very active catalyst. 
Consumption of particulate (which in preferred cases is cracking catalyst) 
can be very high. The cost associated therewith, especially when high 
nickel and vanadium are present in amounts greater than 0.1 ppm in the 
feedstock can, therefore, be very great. Depending on the level of metal 
content in feed and desired catalyst activity, tons of catalyst must be 
added daily. For example, the cost of a catalyst at the point of 
introduction to the unit can rise as high as $2,000/ton. As a result, a 
unit consuming 20 tons/day of catalyst would require expenditures each day 
of at least $40,000. For a unit processing 40,000 barrels per day this 
would represent a processing cost of $1/barrel or 2.5 cents/gallon, for 
catalyst use alone. 
In addition to catalyst costs, an aged and highly nickel and vanadium laden 
catalyst can also bring about a reduction in yield of valuable and 
preferred liquid fuel products, such as gasoline and diesel fuel, and 
instead, produce more undesirable, less valuable products, such as dry gas 
and coke. A high level of nickel and vanadium on catalyst can also 
accelerate catalyst deactivation, thus further reducing operating profits. 
Because of this required daily addition of catalyst (or sorbent) 
particulates, there results immediate and complete mixing of these 
microspherical particulates both fresh in performance and low in 
contaminants (usually nickel, vanadium, iron, copper, and sodium) with 
other microspherical particulates high in these adverse elements and very 
low in activity and which particulates have been in the unit for varying 
times as long as 60-90 days or longer. These older catalysts have 
drastically dropped in performance while simultaneously accumulating these 
aforementioned deleterious metal contaminants which catalytically greatly 
accelerate production of hydrogen and coke as well as dry gas. 
As a result, industry has long felt a need to have a means by which the 
older (earlier added) catalyst can be selectively removed without 
inclusion or entrainment of the newer (freshly added) catalyst in order to 
reduce catalyst addition rates while at the same time maintaining better 
activity, selectivity and unit performance. Because of the very small size 
of these particles, billions of particles are involved, and mechanical 
separation has not been feasible even if one could rapidly identify by 
some means, as for example, color, which particles are old, and which are 
new. 
II. Description of the Prior Art 
"Magnetic Methods For The Treatment of Materials" by J. Svovoda published 
by Elsevier Science Publishing Company, Inc., New York (ISBNO-44-42811-9) 
Volume 8) discloses both theoretical equations describing separation by 
means of magnetic forces with the corresponding types of equipment that 
may be so employed. Specific reference at pages 135-137 is made to 
cross-belt magnetic separators and pages 144-149 refer to belt magnetic 
separators involving a permanent magnet roll separator, as well as pages 
161-197 which refer to high gradient magnetic separators, all of which are 
efficient in separating magnetic particles. 
A manual search in the U.S. Patent Office, Class 55, subclass 3; Class 208, 
subclasses 52CT, 113, 119, 120, 121, 124, 137, 139, 140, 152, 251R, and 
253; Class 209, subclasses 8, 38, 39, and 40; and Class 502, subclasses 5, 
20, 21, 38, 515, 516, and 518 found principally the following references: 
PATENTS RELATED TO HYDROCARBON PROCESSING 
U.S. Pat. No. 4,359,379 and 4,482,450 to Ushio (assigned Nippon Oil 
Company), both disclose catalytic cracking and hydrotreating processes for 
carbo-metallic feedstocks by depositing (adding) nickel, vanadium, iron, 
and/or copper (originally contained in the heavy oil), and then separating 
the old catalyst utilizing a high gradient magnetic separator (HGMS). The 
magnetizement is derived from the metals contained in the starting oil. 
U.S. Pat. No. 2,348,418 (col. 2) to Roesch (Standard Oil, Indiana) 
regenerates catalyst by adding a magnetic substance, such as iron or 
nickel to the catalyst before the catalyst is introduced into a magnetic 
separator. 
PROCESSES AND APATUS FOR MAGNETIC SEATION 
U.S. Pat. No. 1,390,688 (1921) to Ellis discloses magnetic separation of 
catalytic material by means of an electromagnetic or permanent magnet, 
wherein finely divided nickel or magnetizable nickel oxide are removed 
from fatty acid oils prior to filtration of the fatty acid oils. The oil 
and suspended catalyst are allowed to flow past a plate under which 
electromagnets are placed, causing the suspended catalyst to collect in a 
spongy mass around the magnetic poles and allowing the oil to pass off in 
the state of substantial clarity. 
U.S. Pat. No. 3,010,915 (1961) to Buell discloses a process involving 
nickel on kieselguhr catalyst for recycle of magnetically separated 
magnetic catalyst back to be used for further reactions. The catalyst size 
is from 1 to 8 microns. The specific nature of the magnetic separator is 
not considered the critical feature of the invention. 
PATENTS RELATED TO SUPERAMAGNETISM AND FERRO/FERROMAGNETISM 
U.S. Pat. No. 4,695,392 (1987) to Whitehead produces magnetic particles for 
use in separations by precipitation of superparamagnetic iron oxide. The 
precipitate is washed repeatedly with water by magnetically separating it 
and redispersing it until a neutral pH is reached. The precipitate is then 
washed once in an electrolytic solution, e.g. a sodium chloride solution. 
The electrolyte wash step is important to insure fineness of the iron 
oxide crystals. Finally the precipitate is washed with methanol until a 
residue of 1.0% (V/V) water is left. 
Repeated use of magnetic fields to separate the iron oxide from suspension 
during the washing steps is facilitated by superparamagnetism. Regardless 
of how many times the superparamagnetic particles are subjected to 
magnetic fields, they never become permanently magnetized and consequently 
can be redispersed by mild agitation. Permanently magnetized 
(ferromagnetic) metal oxides cannot be prepared by this washing procedure 
as they tend to magnetically aggregate after exposure to magnetic fields 
and cannot be homogeneously redispersed. 
U.S. Pat. No. 4,824,587 Apr. 25, 1989) to Kwon. Composites of coercive 
particles which retain residual magnetism when the magnetic field is 
removed, and superparamagnetic particles consisting of a coercive 
particulate material which can be maintained within the solid matrix, and 
a superparamagnetic particulate material. In the preferred composites, the 
superparamagnetic particulate materials are dispersed in the solid matrix 
in such a way that the composite behaves as if the superparamagnetic 
particles encapsulate the coercive particles. 
Coercive particles useful in this invention are any magnetic particles 
which are of a size greater than that at which superparamagnetism is 
exhibited. Preferably, the coercive particles are of a size within a range 
such that said particles exhibit a coercivity great enough to exhibit 
interaction effects when combined with the superparamagnetic particles. 
The coercivity of such particles can depend upon factors such as the 
shape, size and composition of the particles. Most preferably, such 
particles are of a size very nearly equal to, or equal to, the single 
domain stage. 
Ferrofluids are colloidal aqueous dispersions of finely divided magnetic 
particles of subdomain size, i.e. from about 20 to 200 A, and are 
characterized by resistance to settling in the presence of gravitational 
or magnetic force fields and resistance for change of its liquid 
properties in the presence of an applied magnetic field. Ferrofluids also 
display superparamagnetism. The preparation and properties of ferrofluid 
compositions are described in U.S. Pat. Nos. 3,531,413 and 3,917,538 which 
are incorporated herein by reference. Preparation of ferrofluids and the 
laws and relationships that govern their behavior are treated in "Fluid 
Dynamics" and Science of Magnetic Liquids", R. E. Rosensweig, Advances in 
Electronics and Electron Physics, Vol. 48 (1979), pp. 103-199, Academic 
Press. 
SUMMARY OF THE INVENTION 
I. General Statement of the Invention 
This invention embodies the discovery that at higher levels of iron, 
unusual ferro/superparamagnetic properties never previously reported, to 
out knowledge, form in certain aged cracking catalyst, apparently under 
little understood, but unusual conditions of metal deposition and severe 
operating and regeneration conditions. Because of these extemely strong 
magnetic properties, it has now been determined that when these properties 
are present, substantial improvement in magnetic separation of old, 
low-activity, high metals containing catalysts from fresh, high activity, 
low-metals catalysts, can be achieved. 
The term "superparamagnetism" is defined as that magnetic behavior 
exhibited by iron oxides with crystal size less than about 300 Angstrom, 
which behavior is characterized by responsiveness to a magnetic field 
without resultant permanent magnetization. That is, there is little or no 
hysterysis or residual magnetism when the field is removed. 
Superparmagnetism is understood as meaning the ideal magnetically soft 
behavior of a ferromagnetic or paramagnetic solid particle. Such behavior 
is exhibited when the magnetic energy K.times.V of a solid particle 
(K=anisotropy constant, V=particle volume) decreases continuously and at 
some point reaches the order of magnitude of the thermal energy k.times.T 
(k=Boltzmann constant, T=absolute temperature in Kelvin), so that there is 
no longer any permanent dipole. For cubic ferrites (the solid particles I 
according to the invention belong to this class of compounds), the 
critical maximum particle diameter from which this behavior is exhibited 
is about 5-15 nm (cf. C. P. Bean and J. D. Livingston, Superparamagnetism, 
J. Appl. Phys., Supplement to Volume 30, No. 4, pages 120S-129S, 1959). In 
the case of the cubic ferrites, assuming that they are present as 
monodisperse, substantially pore-free spherical particles, this critical 
particle diameter roughly corresponds to a BET surface area of from 40 to 
130 m&lt;2&gt;/g, determined according to Brunauer, Emmet and Teller (cf. R. 
Brdicka, Grundlagen der Physikalischen. 
The term "ferromagnetism" is defined as that magnetic behavior exhibited by 
iron oxides with crystal size greater than about 500 Angstrom, which 
behavior is characterized by responsiveness to a magnetic field with 
resultant permanent magnetism. "Ferromagnetism" is the similar behavior 
exhibited by iron (element), and is often additionally present in 
superparamagnetic materials. Thus, "superparamagnetism" as used herein 
includes ferromagnetic/superparamagnetic" materials. 
Paramagnetic properties are those reported in the Handbook of Chemistry and 
Physics, pages E122-E127, Vol. 57, 1976-77, CRC Press, and as measured in 
a Johnson-Mathey Balance. 
Like paramagnetic materials, superparamagnetic materials are characterized 
by an inability to remain magnetic in the absence of an applied magnetic 
field. Superparamagnetic materials can have magnetic susceptibilities 
nearly as high as ferromagnetic materials and far higher than paramagnetic 
materials. 
Ferromagnetism and superparamagnetism are properties of lattices rather 
than ions or gases. Iron oxides such as magnetite and gamma ferric oxide 
exhibit ferromagnetism or superparamagnetism depending on the size of the 
crystals comprising the material, with larger crystals being 
ferromagnetic. 
As generally used, superparamagnetic and ferromagnetic materials alter the 
nuclear magnetic resonance (MR) image by decreasing T2 resulting in image 
darkening. When injected, crystals of these magnetic materials accumulate 
in the targeted organs or tissues and darken the organs or tissues where 
they have accumulated. 
Normally, contaminating metals such as nickel and iron when present on 
equilibrium catalyst, are present as paramagnetic species, as previously 
determined by measurement of magnetic susceptibility properties on a 
"Faraday balance" described in J. Svaboda. These elements (or ions of 
these elements) exhibit small but finite and useful paramagnetic 
susceptibilities which allow or facilitate magnetic separation of 
particles containing greater amounts of metal from those containing lesser 
amounts of metal. However, it is apparent that much better separation of 
old from fresh catalyst could be achieved if these metal contaminants 
could somehow be given much higher magnetic properties. 
In particular, it now appears that this rare superparamagnetism which has 
just been discovered in catalysts, is strongly associated with easier and 
improved separation. While this unusual specie has not been fully 
identified chemically, nor determined as to how it forms, its presence can 
be detected by this display of high magnetic susceptibility properties as 
measured on a Johnson-Mathey Magnetic Susceptibility Balance, and does 
appear to be associated with the presence of higher iron concentrations. 
It may possibly also be related to nickel content, and perhaps even to 
rare earths and zeolites, present in today's cracking catalysts. 
Its presence can be observed by measurement of magnetic susceptibility of 
equilibrium catalyst on a Johnson-Mathey Magnetic Susceptibility Balance, 
and more preferably, by magnetic susceptibility balance measurement of 
magnetic fractions obtained by means of multi-step magnetic separation and 
most preferably by comparing these values with metal content on the 
catalyst. When magnetic susceptibility rises significantly above values 
predicted based on content of paramagnetic iron and nickel, 
superparamagnetism is indicated. 
These measurements of magnetic susceptibility (Xg) have been made on a 
Johnson-Mathey Magnetic Susceptibility Balance, manufactured by Sherwood 
Scientific, Limited of Cambridge, England, and sold by Johnson-Mathey 
Corporation of Wayne, Pennsylvania. This device resulted from a Johnson 
Mathey collaboration with Professor D. F. Evans of Imperial College, 
London, England, who is a noted authority on paramagnetism. (See 
Johnson-Mathey brochure 89-460, 1990. 
It is not yet clear when and how these superparamagnetic species form, and 
this invention is not to be limited to any explanation of this phenomenon 
or to any theory. It is, however, possible to some extent, to describe its 
unique properties. 
Originally, this strong magnetic property was considered to be evidence for 
the presence of only a ferromagnetic specie. However, during his magnetic 
investigation of catalysts submitted by the present inventor by means of a 
spinning sample magnetometer by Professor L. N. Mulay of Penn State 
University, a noted authority on magneto chemistry, only very slight 
magnetic anisotropy was reported. (Magnetic anisotropy is an identifying 
characteristic of ferromagnetic substances.) He also has noted that these 
specimens containing high magnetic susceptibility values also appear to 
possess superparamagnetic behavior. Therefore, he has suggested that we 
identify our unknown as a ferro/superparamagnetic composite. 
Apparently the ferro/superparamagnetic phenomenon that we have observed, 
and as described by Mulay, is displayed by very small magnetic particles, 
many probably less than 200 Angstrom in size, which very likely consist of 
single, or small coupling of several, and possibly, partially oriented 
domains. He has suggested that if these domains are combined with others, 
they should also very likely have ferromagnetic properties, as he has 
observed. When these domains are clustered in groups of two or more, they 
may interact and thus create the magnetic anisotropy associated with 
ferromagnetism. 
But single domains, unable to interact with other domains, do not display 
this anisotropy. They are, therefore, described as superparamagnetic 
species, because they have these magnetic properties many-fold as strong 
as an equivalent number of paramagnetic ions or elements. A test of 
superparamagnetism reportedly can be made by plotting magnetic 
susceptibility as observed, divided by magnetic susceptibility at 
saturation versus field strength (H) in Oersteds divided by absolute 
temperature in degrees Kelvin. Also, superparamagnetism is indicated by 
intense Nuclear Magnetic Resonance (NMR) signal. Paramagnetism on the 
other hand does not reach saturation as the magnetic field strength 
increases, and a plot of magnetic susceptibility versus field strength, 
shows a continuing straight line increase. (See FIG. 1.)

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
II. Utility of the Invention 
EXAMPLE 1 (Best Mode) 
FIG. 11 shows a preferred process employing this invention. Bottoms derived 
from distilling off a portion of crude oil 10 enter the conventional riser 
reactor at 11. In the riser the reduced crude contacts regenerated 
catalyst returning from the regenerator line 15 and travels up the riser 
16, cracking the reduced crude and generating product 18 and spent 
catalyst 17 which is contaminated with coke and metals from the reduced 
crude. The spent catalyst 17 enters the regenerator 20 via line 19 and is 
oxidized with air 21 to burn off coke and thereby regenerate the catalyst 
for return to the riser 16. About 8% of the regenerated catalyst is 
diverted through line 24 through catalyst cooler 25 (optional) to magnetic 
separator 26, where it is spread onto belt 27, moves past roller 28, (a 
high intensity rare earth-containing permanent magnetic roller) which 
splits the catalyst into two (or more) portions 29 to 32. The more 
magnetic (more metal-contaminated) portions, e.g. 29, and/or 30, are 
rejected for chemical reclaiming, metals recovery, further magnetic 
separation, or disposal. The less magnetic (less metal-contaminated) 
portions 31 and/or 31 and 32 are recycled through line 33 back to the 
regenerator 20. 
Following is an example of a typical catalytic cracking process operating 
commercially with a catalyst containing a high level of superparamagnetic 
material. (Although the mechanism of formation of this high magnetic 
specie is not known with certainty, it is related to operating at high 
regeneration temperature severity on a catalyst with a high level of iron 
on the catalyst and in the feedstock also.) In the following table, 
comparison is made between processing a commercial run on a catalyst high 
in superparamagnetic properties, while processing a feedstock also heavily 
loaded with iron and containing over 10,000 ppm of iron on the catalyst, 
and compared with processing a very similar feedstock, but low in iron, 
over the same catalyst but also with a low iron content and low 
superparamagnetic property. In both cases, the same virgin catalyst is 
used, but the low iron catalyst has a low iron content because of the low 
iron in the feed. 
Table I shows the amount of feedstock being processed, the operating 
conditions, the composition, and the results of processing. 
Example 2 (Comparative Paramagnetic Catalyst) 
In order to make direct comparisons between paramagnetic properties of iron 
and nickel on these catalysts and these unusual values as reported here, 
the following experiments are performed: 100 grams (gram) of a low rare 
earth containing cracking catalyst similar to that used in our catalytic 
cracking units, is slurried with 150 ml. of H.sub.2 O. A solution of iron 
sulfate (Fe.sub.2 (SO.sub.4).sub.3.5H.sub.2 O) is prepared by dissolving 
4.38 gram in 50 ml. of water. This represents 1% by weight of iron to be 
deposited on the virgin catalyst. The iron sulfate solution is heated to 
boiling to assure complete solution, and then rapidly mixed with the 
catalyst slurry. This mixture is allowed to remain in contact for 12 
hours, with intermittent shaking to insure good contact. After standing 
for 12 hours, the catalyst slurry is dewatered on a filter and the filter 
cake recovered. The filter cake is oven dried, calcined at 1200.degree. F. 
for four hours and allowed to cool. A sample is taken for iron analysis, 
and a second sample for measurement of magnetic susceptibility. 
A second sample of higher iron content containing catalyst, (targeted at 
21/2 times the iron concentration of the first sample) is also prepared by 
the same method. In a further experiment, iron oxalate. (Fe.sub.2 (C.sub.2 
O.sub.4).sub.3.2H.sub.2 O) is also used as the source of iron for 
preparation and examination. To confirm the potential contribution also 
from nickel, similar preparations are made with NiCl.sub.2.6H.sub.2 O. The 
chemical analyses for all of these impregnation are shown in Table IIA, 
and the increase in metal content shown in Table IIA is used to determine 
the added iron or nickel. Referring to Table IIB, virgin catalyst iron and 
nickel content and virgin catalyst magnetic susceptibility are subtracted 
from total values to determine the effect of these added ions. Comparing 
the low increase in magnetic susceptibility of these samples which 
represent paramagnetic contributions of ionic iron and nickel to those 
found in our high magnetic susceptibility catalysts, clearly demonstrates 
the presence of new and unusual species. For example, from these 
experiments, it is shown that adding 1% of what is obviously paramagnetic 
iron, increases magnetic susceptibility approximately 1.5 to 
2.2.times.10.sup.-6 emu/grams. (for nickel 1.35 to 1.62.times.10.sup.-6 
emu/gram.) These experimental paramagnetic values for iron and nickel 
agree quite well with published values and further confirm the validity of 
the experiments and the measuring equipment. 
Example 3 (Comparison of Used Magnetic Catalysts With Used 
Superparamagnetic Catalysts and With Synthetic Magnetite Loaded Catalyst) 
Table III, samples 1 and 2, compare the magnetic susceptibility properties 
of two of these unusual equilibrium catalysts taken from two commercial 
operating units with two equilibrium catalysts having very low values. 
Comparison is also made with these samples which are synthetic blends, one 
with magnetite and one with iron oxide, both obtained from Aldrich 
Chemical Company. In this table we have chosen to report these high values 
of this superparamagnetic substance in terms relative to magnetite. 
However, because of the presence of this unusual material in small 
quantities and undoubtedly very small crystallites, its structure has not 
yet been determined as being magnetite-related. Note samples 1 and 2 have 
at least 6 to 9 times as much of this magnetic substance as samples 3 and 
4. 
To estimate and reference the percentage of superparamagnetic substance 
shown in Table II to be present in used catalyst, the value of observed 
magnetic susceptibility is divided by magnetic susceptibility of magnetite 
when present in 100 percent concentration. For example, in catalyst #1, 
the observed superparamagnetic value of 23.3.times.10.sup.-6 emu/gm is 
divided by 28,800.times.10.sup.-6 emu/gm, the value from 100% magnetite to 
give a value of 0.08% of magnetite like material in this sample. 
When this superparamagnetic specie is present as shown in Table III, values 
of 54 to 124.times.10.sup.-6 emu/gram or greater, for 1% iron are 
observed. This value, obviously, is many-fold greater than anticipated for 
paramagnetic iron (1.6 to 2.2.times.10.sup.-6 emu/gram). Note also that 
for the iron oxide preparation at 5% level, the paramagnetic value agrees 
almost exactly with values observed for our impregnations. If magnetic 
susceptibility is plotted versus incremental iron, the presence of this 
highly magnetic susceptibility substance can be detected by the rate at 
which it changes as iron and/or nickel, or iron plus nickel changes, as 
shown in FIG. 4. 
Consequently, it has now been discovered that when iron is present in 
significant amounts above that found in virgin catalyst, namely 
3,000-4,000 ppm, that under certain conditions, and as iron is 
proportionately increased, the catalyst under certain operating conditions 
not yet fully identified, no longer displays the properties of a 
paramagnetic ion, such as highly dispersed nickel and iron. 
Instead it has now been discovered that under conditions of significant 
iron content (in the feedstock or artificially added) in the range of 
1-100 ppm concentration in feedstock accumulating on the catalyst in 
amounts of 500 ppm greater than on virgin catalyst iron, (and perhaps 
nickel) that at certain yet undefined conditions, new and much stronger 
magnetic properties may begin to appear. 
Instead of observing magnetic susceptibilities much lower than 
5.times.10.sup.-6 emu's/gram (Table IIB) for a 1% normalized concentration 
increase of iron (or nickel, a magnetic susceptibility begins to appear, 
which for the total catalyst, is roughly 2-20, or even 50 times this 
paramagnetic value, and this level of magnetic susceptibility increase 
ranges from 5-50 or even up to 200.times.10.sup.-6 emu's gram per of 1% 
iron increase on catalyst. 
This superparamagnetic substance has a high Curie point (preferably greater 
than 500.degree. F.). 
Table III demonstrates the considerable increase in susceptibility of the 
entire catalyst. If these catalyst samples consisting of millions of 
particles 2-150 microns in diameter, are divided up into many fractions by 
magnetic separation by either a high gradient separation (HGMS) or a rare 
earth magnetic roller (RERMS) method, the high magnetic fractions will 
have extremely high magnetic susceptibilities of as high as 
60.times.10.sup.-6 emu/gram or even higher. Once catalyst sample has a 
magnetic susceptibility of 100.times.10.sup.-6 without fractionation into 
cuts and a magnetic cut of one sample has a value of 284.times.10.sup.-6 
emu/gram. 
Example 4 (Comparison of High and Low Magnetic Susceptibility of Used 
Equilibrium Catalyst) 
FIGS. 5A, 6A, 7A, and 8A show the magnetic susceptibility of various cuts 
data obtained on the rare earth roller magnetic separator (RERMS) of 
Examples 1, 2, 3, and 4 in Table II. In FIGS. 5A and 6A, note how magnetic 
susceptibility rises rapidly in the higher magnetic portions of samples 1 
and 2 of Table III, but FIGS. 7A and 8A show only a small tail of high 
value for samples 3 and 4, while most cuts stay at reported values for 
paramagnetic iron and nickel. A similar separation (not shown) is made on 
sample #1 on a high gradient magnetic separator (HGMS) and similar results 
were obtained showing that HGMS can also be used. 
Example 5 (Relationship of High Magnetic Susceptibility and Iron Content) 
When the change in iron is plotted versus percent magnetic, as shown in 
FIGS. 5B, 6B, 7B, and 8B for these same four catalysts, it can be seen how 
rapidly iron content rises, especially for samples 1 and 2. If one plots 
magnetic susceptibility versus iron increase, the slope rises as high as 
110.times.10.sup.-6 emu/gram for 1% concentration increase versus iron 
content for samples 1 and 2, while this increase is just barely 
detectable for samples 3 and 4. For these catalyst at some critical point, 
and extrapolating to a 100% concentration of iron, for the Canton sample, 
#2, it rises as much as 12,400.times.10.sup.-6 emu/gram. This value is 
approximately 1/3 the value observed for magnetite in Table III. 
While it is difficult to identify the specific magnetic specie, and we do 
not wish to be confined to a given specie, it is apparent that a highly 
magnetic specie has formed in varying amounts in all four cases, two being 
very large, and two being very small. FIG. 4 showed the relationship 
between iron content and magnetic susceptibility of a very highly magnetic 
specie. Here there was a rise of 200.times.10.sup.-6 emu/gram for a 1% 
iron increase, or 20,000.times.10.sup.-6 emu/gram for an extrapolation to 
a 100% iron specie. 
Example 6 (Estimation of Curie Temperature) 
To confirm that this is indeed a superparamagnetic specie which is forming, 
a sample, as previously described, having a very high value of 
100.times.10.sup.-6 emu/gram, is heated in an open flame to a temperature 
of about 1200.degree. F. in a glass tube container, and then plunged into 
a Johnson Mathey Magnetic Balance where it is allowed to cool while its 
magnetic properties is measured. FIG. 9 shows the magnetic susceptibility 
as a function of time. At zero time, after heating, magnetic 
susceptibility had dropped to a value approaching a paramagnetic value. 
But as it cools through the Curie point, magnetic susceptibility increases 
rapidly and returns to the original value of the measured catalyst, thus 
confirming by a second means, the presence of a highly magnetic and 
temperature sensitive specie, superparamagnetism. 
It should also be noted that superparamagnetic properties not only 
intensify with higher iron content, but that they also increase with time 
so that older particles change in properties from the paramagnetic 
properties possessed at low metal levels previously cited, to very high 
levels of magnetic susceptibility. 
FIGS. 5A, 6A, 7A, and 8A, show magnetic susceptibility as a function of 
percent magnetic and FIGS. 5B, 6B, 7B, and 8B as a function of iron 
content. Removal of metal-containing catalyst is obviously facilitated by 
this unusual and highly magnetic property. 
Example 7 (Relationship between Superparamagnetic Susceptibility and 
Catalyst Activity and Selectivity) 
Table IV presents catalytic microactivity data obtained on magnetic 
fraction samples of the RCC.RTM. Process cracking catalyst (see FIGS. 5A 
and 5B). It will be noted that with the higher magnetic susceptibility 
fractions, catalyst conversion is low (61.4 vol. %) and the coke factor 
(2.77) and hydrogen production (0.34 wt. %) both high for the most 
magnetic fraction versus 71.9 vol. % conversion, coke factor of 2.30 and 
hydrogen production 0.24 wt. % for the least magnetic fraction #1. By the 
same comparison, fraction #1 has 60.9 vol. % gasoline, and has a magnetic 
susceptibility of 12.0.times.10.sup.-6 emu/gram versus 54.59 vol. % 
gasoline and a magnetic susceptibility of 58.2.times.10.sup.-6 emu/gram 
for the most magnetic. The catalyst sample as received had an overall 
magnetic susceptibility of 25.7.times.10.sup.-6 emu/gram. 
In FIG. 10, magnetic susceptibility is plotted versus vol. % catalyst 
conversion and shows the strong relationship between high magnetic 
susceptibility and low catalyst activity. 
Table V summarizes the results of testing a catalyst (sample 3) that shows 
an overall magnetic susceptibility of only 2.6.times.10.sup.-6 emu gram. 
The data is shown in FIG. 7A and the iron analysis in FIG. 7B. It will be 
noted in FIG. 7A that almost all the cut fractions have a value of less 
than 2.times.10.sup.-6 emu/gram with only a trace of supermagnetic 
material present in the most contaminated fraction. That poor separation 
is confirmed by Table V, which shows that there is very little change in 
conversion between catalyst fractions. This data shows the relationship 
between magnetic susceptibility and separation efficiency. The importance 
of superparamagnetic properties to enhance separation is clearly shown by 
contrast for these two samples used by comparing the data in Table IV vs. 
V. 
TABLE I 
______________________________________ 
High Super 
Low Super 
Paramagnetic 
Paramagnetic 
Catalyst Catalyst 
______________________________________ 
Total charge B/D* 36,037 39,965 
Mag Suscept. .times. 10.sup.-6 emu/gm 
108 20 
Conversion vol. % 69.8 70.9 
Dry Gas wt. % 3.6 3.9 
C.sub.3 -C.sub.4 vol. % 
22.4 20.8 
C.sub.5 - 430.degree. F. vol. % 
50.8 52.6 
430-630.degree. F. vol. % 
18.0 17.9 
630.degree. F. slurry vol. % 
12.2 11.2 
Coke wt. % 9.3 10.9 
RBC wt. % 4.0 5.6 
Catalytic coke wt. % equals 
5.3 5.3 
Coke wt. %-RBC wt. % 
H.sub.2 SCF/B 105 103 
Vol. % Gain 3.4 2.6 
UOPK 11.8 11.7 
Gravity .degree.API 
19.8 18.2 
Reactor Temp .degree.F. 
971 976 
Regen Temp .degree.F. 
1335 1341 
Cat/Oil 8.3 8.6 
Wt. % Sulfur 2.0 2.2 
Fe ppm on catalyst 
10,800 7,100 
Ni ppm on catalyst 
1,900 1,950 
V ppm on catalyst 4,100 5,000 
Fresh Cat Addn #/B 
0.64 1.10 
Equil Cat Addn #/B 
0.62 0.39 
Total #/B 1.26 1.49 
Feed Ni ppm 8 6 
V ppm 22 20 
______________________________________ 
*Average of all data from four weeks processing 
TABLE IIA 
______________________________________ 
Iron (or Nickel) on Catalyst 
Targeted 
Nominal Actual Virgin Net 
Con- Analysis 
Catalyst 
Increase 
Sample 
Source of 
centration ppm ppm ppm 
# Element ppm (x-ray fluorescence) 
______________________________________ 
1. Iron 10,000 12,440 3,500 8,940 
Sulfate 
2. Iron 25,000 28,387 3,500 24,887 
Sulfate 
3. Iron 10,000 14,418 3,500 10,918 
Oxalate 
4. Nickel 5,000 4,593 24 4,569 
Chloride 
5. Nickel 10,000 7,401 24 7,377 
Chloride 
______________________________________ 
TABLE IIB 
__________________________________________________________________________ 
MAGNETIC SUSCEPTIBILITIES OF TABLE 1A SAMPLES) 
(Xg .times. 10.sup.-6 emu/gram) 
Observed 
Calculated* 
Calculated 
Observed 
Xg Increase 
Xg Incr. 
Xg Incr. 
Source of 
Observed 
Virgin 
Due to for 1% Metal 
for 100% Metal 
Sample # 
Element 
Xg Xy Element 
Increase 
Increase 
__________________________________________________________________________ 
1. Iron 2.35 0.78 1.57 1.64 164 
Sulfate 
2. Iron 5.66 0.78 4.88 1.76 176 
Sulfate 
3. Iron 3.13 0.78 2.35 2.15 215 
Oxalate 
4. Nickel 
1.52 0.78 0.74 1.62 162 
Chloride 
5. Nickel 
1.78 0.78 1.00 1.35 135 
Chloride 
__________________________________________________________________________ 
*Based on incremental metal analysis 
TABLE III 
__________________________________________________________________________ 
Iron Iron Est. 
Commercial Analysis 
Analysis 
Iron 
Nickel 
Para-Mag Virgin 
Max. 
Actual 
Difference 
Cracking ppm ppm Incr. 
Analysis 
Increase Cat- Para-Mag 
Superparamag. 
Catalyst Equil. Cat 
Vir. Cat 
ppm ppm Table I alyst Contrib. 
Contrib. 
__________________________________________________________________________ 
Fe 0.8 
RCC 7,800 3,500 
4,300 
1,800 + 1.0-1.3 
= 2.4 25.7 
23.3 
Ni 0.3 
Fe 0.5 
FCC Canton 
6,400 3,500 
2,900 
1,100 + 0.8 = 1.5 37.5 
36.0 
Ni 0.2 
FCC Fe 0.17 
Catlettsburg 
4,400 3,500 
900 
400 + 1.0 = 1.2 2.6 1.4 
Ni 0.06 
Fe 0.35 
FCC St. Paul 
5,400 3,500 
1,900 
400 + 1.3 = 1.7 3.2 1.5 
Ni 0.06 
Virgin Catalyst + 35,000 6.48 + 1.0 = 7.5 7.3 0 
5% Fe.sub.2 O.sub.3 blend 
Virgin Catalyst + 7,300 1.35 + 1.0 = 2.3 222 220 
1% magnetite 
blend Fe.sub.3 O.sub.4 
Virgin Catalyst + 10,488 1.90 + 1.3 = 3.1 292 289 
1.5% magnetite 
blend 
Virgin Catalyst + 7,300 1.35 + 1.0 = 2.3 186 184 
1% magnetite 
blend + 4 hrs. 
1200 F. in air 
__________________________________________________________________________ 
Commercial Est. % 
Cracking Xg for 
Xg for Xg for 
Superpara- 
Catalyst 1% Fe 
1% Fe + Ni 
100% 
Mag. 
__________________________________________________________________________ 
1. 
RCC 54.2 
38 5,400 
0.08% 
2. 
FCC Canton 
124.1 
90 12,400 
0.12% 
3. 
FCC 15.6 
10.8 1,008 
0.005% 
Catlettsburg 
4. 
FCC St. Paul 
7.9 6.5 650 
0.005% 
5. 
Virgin Catalyst + 
1.85 
1.85 185 
0% 
5% Fe.sub.2 O.sub.3 blend 
6. 
Virgin Catalyst + 
301 30,100 
100% 
1% magnetite 
blend Fe.sub.3 O.sub.4 
7. 
Virgin Catalyst + 
276 avg. 27,600 
100% 
1.5% magnetite 28,800 
blend 
8. 
Virgin Catalyst + 
252 25,200 
88% 
1% magnetite 
blend + 4 hrs. 
1200 F. in air 
__________________________________________________________________________ 
TABLE IV 
__________________________________________________________________________ 
MAT Results on RCC Magnetic Separation Fractions 
1/15/90 RCC Equilibrium Sample - OSNA Separation 
(Magnetic Off First) 
Calc. 
1st 2nd 3rd 4th 5th 6th 6th 
Fraction Feed N Mag 
N Mag 
N Mag 
N Mag 
N Mag 
N Mag 
Mag 
__________________________________________________________________________ 
Conversion, V % 
65.47 
71.91 
69.27 
67.47 
63.91 
61.16 
60.96 
61.43 
Conversion, W % 
63.98 
70.98 
67.59 
65.83 
62.32 
59.40 
59.11 
59.70 
Conv/(100-Conv) 
1.776 
2.342 
2.085 
1.927 
1.654 
1.463 
1.446 
1.481 
Yields, W % 
C2 & Lighter 
1.31 1.43 1.37 1.29 1.31 
1.20 1.34 1.22 
Hydrogen 0.31 0.24 0.27 0.29 0.32 
0.32 0.38 0.34 
Coke 4.57 5.38 4.86 4.66 4.50 
4.20 4.20 4.10 
Total C3's 
3.36 4.08 3.77 3.49 3.28 
2.96 2.92 2.94 
Propane 0.60 0.99 0.72 0.60 0.52 
0.45 0.43 0.42 
Propylene 
2.76 3.09 3.05 2.89 2.76 
2.51 2.50 2.51 
Total C4's 
7.28 8.87 8.11 7.63 7.05 
6.47 6.19 6.38 
IC4 3.07 4.44 3.67 3.31 2.79 
2.51 2.15 2.35 
NC4 0.56 0.93 0.69 0.58 0.49 
0.42 0.38 0.39 
Butenes 3.65 3.50 3.74 3.75 3.77 
3.54 3.66 3.65 
Gasoline 47.46 
50.31 
49.49 
48.76 
46.16 
44.56 
44.47 
45.06 
LCO 24.79 
24.79 
21.60 
23.10 
24.01 
25.65 
27.25 
26.72 
27.13 
CSO 11.23 
11.23 
8.30 9.30 10.05 
12.03 
13.35 
14.16 
13.17 
Gasoline, V % 
57.47 
60.95 
59.96 
59.07 
55.92 
53.99 
53.87 
54.59 
LCO, V % 24.60 
20.93 
22.64 
23.65 
25.45 
27.03 
26.51 
26.92 
CSO, V % 9.93 7.16 8.09 8.88 10.64 
11.81 
12.53 
11.65 
Coke Factor 
2.57 2.30 2.33 2.42 2.72 
2.87 2.91 2.77 
Ni, ppm 1860 1100 1400 1600 NA 2200 2400 2490 
Fe, ppm 9160 7910 7200 NA 6080 5900 5700 
Yield, W % 
100.0 
15.40 
14.90 
12.60 
14.10 
15.20 
14.00 
13.80 
Magnetic 25.7 12.0 16.8 21.1 24.1 
27.8 38.9 58.2 
Susceptibility .times. 
10.sup.-6 emu/gm. 
__________________________________________________________________________ 
TABLE V 
__________________________________________________________________________ 
Catlettsburg FCC Study 
Base 1st 2nd 3rd 4th 5th 6th 6th 
Equilibr 
Mag Mag Mag Mag Mag Mag N 
__________________________________________________________________________ 
Mag 
FEEDSTOCK RPS RPS RPS RPS RPS RPS RPS RPS 
CAT/OIL RATIO 4.62 4.53 4.54 4.50 4.51 
4.50 4.52 4.59 
REACTION TEMP 960.00 
960.00 
960.00 
960.00 
960.00 
960.00 
960.00 
960.00 
F. 
REACTION TIME, 25.00 
25.00 25.00 
25.00 25.00 
25.00 25.00 
25.00 
SECONDS 
WHSV 31.20 
31.80 31.70 
32.00 31.90 
32.00 31.80 
31.40 
CONVERSION, 72.54 
73.39 75.07 
70.66 72.56 
73.17 72.43 
73.58 
WT % 
CONVERSION, 74.44 
75.28 77.01 
72.52 74.40 
75.02 74.27 
75.47 
VOL % 
PRODUCT YIELDS, WT % 
ON FRESH FEED 
C2 & LIGHTER 1.33 1.24 1.33 1.22 1.15 
1.26 1.19 1.24 
HYDROGEN 0.08 0.08 0.08 0.07 0.07 
0.08 0.07 0.07 
METHANE 0.41 0.36 0.38 0.37 0.32 
0.37 0.35 0.36 
ETHANE 0.36 0.34 0.36 0.33 0.32 
0.33 0.32 0.33 
ETHYLENE 0.48 0.47 0.50 0.45 0.44 
0.47 0.45 0.48 
CARBON 3.91 4.27 4.08 4.14 3.86 
4.23 4.26 4.71 
PRODUCT YIELDS, WT % (VOL %) 
ON FRESH FEED 
TOTAL C3 
HYDROCARBON 4.75 4.59 4.93 4.41 4.51 
4.70 4.66 4.73 
PROPANE .84 .89 .92 .79 .76 .83 .79 .84 
PROPYLENE 3.91 3.70 4.01 3.61 3.75 
3.87 3.88 3.89 
TOTAL C4 
HYDROCARBON 10.26 
10.18 10.83 
9.61 10.08 
10.32 10.55 
10.39 
I-BUTANE 4.74 5.01 5.22 4.51 4.65 
4.84 4.95 4.89 
N-BUTANE .84 .89 .91 .78 .77 .84 .80 .83 
TOTAL BUTENES 4.68 4.29 4.70 4.32 4.65 
4.65 4.81 4.66 
BUTENES 1.94 1.71 1.89 1.78 1.91 
1.92 2.01 1.93 
T-BUTENE-2 1.57 1.49 1.62 1.46 1.58 
1.56 1.61 1.57 
C-BUTENE-2 1.17 1.09 1.19 1.08 1.17 
1.16 1.19 1.16 
C5-430 F. GASOLINE 52.29 
53.11 53.90 
51.29 52.96 
62.66 51.76 
52.51 
430-650 F. LCGO 20.21 
19.69 18.32 
21.15 20.31 
19.77 20.26 
19.50 
650 F.+ DECANTED 7.24 6.92 6.61 8.19 7.12 
7.06 7.31 6.93 
OIL 
C3 + LIQUID 94.76 
94.49 94.59 
94.64 94.99 
94.51 94.55 
94.05 
RECOVERY 
FCC GASOLINE + ALKYLATE 
ISO/C3 + C4) 
OLEFIN RATIO .56 .63 .60 .57 .56 .57 .57 .58 
COKE SELECTIVITY 1.38 1.45 1.28 1.60 1.37 
1.46 1.52 1.59 
MAG SUSPECT .times. 2.5 19.2 1.90 1.62 1.52 
1.46 1.29 1.27 
D.sup.-6 emu/gm 
YIELD WT % 100.0 
13.8 14.0 15.2 14.1 
12.6 14.9 16.3 
ppm NICKEL 398 382 349 NA 293 269 240 
ppm IRON 4900 4400 4200 NA 4300 4000 3900 
__________________________________________________________________________ 
MODIFICATIONS 
Specific compositions, methods, or embodiments discussed are intended to be 
only illustrative of the invention disclosed by this specification. 
Variation on these compositions, methods, or embodiments are readily 
apparent to a person of skill in the art based upon the teachings of this 
specification and are therefore intended to be included as part of the 
inventions disclosed herein. 
Reference to documents made in the specification is intended to result in 
such patents or literature being expressly incorporated herein by 
reference including any patents or other literature references cited 
within such documents.