Molecular sieve abstract
A Process for the production and uses of a molecular sieve adsorbent
blend product with improved performance characteristics produced
by preparing a zeolite powder, preparing a highly dispersed attapulgite
fiber binder, mixing the zeolite powder with the highly dispersed
attapulgite binder to form a mixture, forming molecular sieve adsorbent
products into a shaped material and calcining the shaped material,
wherein the tapped bulk density of the highly dispersed attapulgite
fibers measured according to DIN/ISO 787 is more than about 550
g/ml.
Molecular sieve claims
What is claimed is:
1. A process for separation of components of a gaseous or a liquid
feed stream comprising passing the components of the gaseous or
liquid feed stream over a molecular sieve adsorbent blend produced
by a process comprising preparing a zeolite product; preparing an
attapulgite binder comprising highly dispersed attapulgite fibers;
mixing the zeolite with the attapulgite binder and water to produce
a mixture; and forming a molecular sieve adsorbent product from
the mixture; wherein the tapped bulk density of the highly dispersed
attapulgite fibers, as measured according DIN/ISO 787 is more than
about 550 g/l.
2. The process of claim 1 wherein the zeolite product comprises
zeolite X or zeolite A.
3. The process of claim 1 wherein the attapulgite binder comprises
from about 5 to about 30 percent of the mixture, by weight.
4. The process of claim 1 wherein the attapulgite binder comprises
from about 5 to about 20 percent of the mixture, by weight.
5. A process for drying a gaseous feed stream comprising passing
the feed stream over a molecular sieve adsorbent blend product comprising
a zeolite blended with a highly dispersed attapulgite binder, wherein
the tapped bulk density of the highly dispersed attapulgite binder
is more than about 550 g/l.
6. The process of claim 5 wherein the zeolite product comprises
zeolite X.
7. A process for adsorption of carbon dioxide from an air stream
comprising passing the air stream over a molecular sieve adsorbent
blend product produced by a process comprising preparing a zeolite
product; preparing an attapulgite binder comprising highly dispersed
attapulgite fibers; mixing the zeolite with the attapulgite binder
and water to produce a mixture; and forming a molecular sieve adsorbent
product from the mixture; wherein the tapped bulk density of the
highly dispersed attapulgite fibers, as measured according DIN/ISO
787 is more than about 550 g/l.
8. The process of claim 7 wherein the zeolite product comprises
zeolite X or zeolite Y.
9. A process for removal of water from a gaseous or liquid ethanol
stream comprising passing the gaseous or liquid ethanol stream over
a molecular sieve adsorbent blend produced by a process comprising
preparing a zeolite product; preparing an attapulgite binder comprising
highly dispersed attapulgite fibers; mixing the zeolite with the
attapulgite binder and water to produce a mixture; and forming a
molecular sieve adsorbent product from the mixture; wherein the
tapped bulk density of the highly dispersed attapulgite fibers,
as measured according DIN/ISO 787 is more than about 550 g/l.
10. A process for separation of nitrogen and oxygen from an air
stream comprising passing the air stream over a molecular sieve
adsorbent blend produced by a process comprising preparing a zeolite
product; preparing an attapulgite binder comprising highly dispersed
attapulgite fibers; mixing the zeolite with the attapulgite binder
and water to produce a mixture; and forming a molecular sieve adsorbent
product from the mixture; wherein the tapped bulk density of the
highly dispersed attapulgite fibers, as measured according DIN/ISO
787 is more than about 550 g/l.
11. A process for removal of sulfur and oxygen containing compounds
from a hydrocarbon stream comprising passing the hydrocarbon stream
over a molecular sieve adsorbent blend product by a process comprising
preparing a zeolite product; preparing an attapulgite binder comprising
highly dispersed attapulgite fibers; mixing the zeolite with the
attapulgite binder and water to produce a mixture; and forming a
molecular sieve adsorbent product from the mixture; wherein the
tapped bulk density of the highly dispersed attapulgite fibers,
as measured according DIN/ISO 787 is more than about 550 g/l.
12. A process for removal of carbon monoxide, carbon dioxide and
nitrogen from a hydrogen gas stream comprising passing the hydrogen
gas stream over a molecular sieve adsorbent blend produced by a
process comprising preparing a zeolite product; preparing an attapulgite
binder comprising highly dispersed attapulgite fibers; mixing the
zeolite with the attapulgite binder and water to produce a mixture;
and forming a molecular sieve adsorbent product from the mixture;
wherein the tapped bulk density of the highly dispersed attapulgite
fibers, as measured according DIN/ISO 787 is more than about 550
g/l.
13. A process for removal of water from a gaseous or liquid hydrocarbon
stream comprising passing the gaseous or liquid hydrocarbon stream
over a molecular sieve adsorbent blend produced by a process comprising
preparing a zeolite product; preparing an attapulgite binder comprising
highly dispersed attapulgite fibers; mixing the zeolite with the
attapulgite binder and water to produce a mixture; and forming a
molecular sieve adsorbent product from the mixture; wherein the
tapped bulk density of the highly dispersed attapulgite fibers,
as measured according DIN/ISO 787 is more than about 550 g/l.
14. A process to separate n-paraffins from a mixture of iso-paraffins
and n-paraffins comprising passing the mixture over a molecular
sieve adsorbent blend produced by a process comprising preparing
a zeolite product; preparing an attapulgite binder comprising highly
dispersed attapulgite fibers; mixing the zeolite with the attapulgite
binder and water to produce a mixture; and forming a molecular sieve
adsorbent product from the mixture; wherein the tapped bulk density
of the highly dispersed attapulgite fibers, as measured according
DIN/ISO 787 is more than about 550 g/l.
15. The process of claim 14 wherein the zeolite product comprises
zeolite A.
16. A process for removal of water from a gaseous or liquid stream
of refrigerants comprising passing the gaseous or liquid stream
over a molecular sieve adsorbent blend produced by a process comprising
preparing a zeolite product; preparing an attapulgite binder comprising
highly dispersed attapulgite fibers; mixing the zeolite with the
attapulgite binder and water to produce a mixture; and forming a
molecular sieve adsorbent product from the mixture; wherein the
tapped bulk density of the highly dispersed attapulgite fibers,
as measured according DIN/ISO 787 is more than about 550 g/l.
17. A process for removal of water and carbon dioxide from air
comprising passing the air over a molecular sieve adsorbent blend
produced by a process comprising preparing a zeolite product; preparing
an attapulgite binder comprising highly dispersed attapulgite fibers;
mixing the zeolite with the attapulgite binder and water to produce
a mixture; and forming a molecular sieve adsorbent product from
the mixture; wherein the tapped bulk density of the highly dispersed
attapulgite fibers, as measured according DIN/ISO 787 is more than
about 550 g/l.
18. The process of claim 17 wherein the zeolit product comprises
zeolite X or zeolite Y.
Molecular sieve description
BACKGROUND OF INVENTION
1. Field of Invention
This invention relates to molecular sieve adsorbents and more particularly
to processes of use of a molecular sieve adsorbent blend comprising
a zeolite and a highly dispersed attapulgite binder. This invention
also relates to processes of use of molecular sieve adsorbent blends
prepared by the process of blending a zeolite with a highly dispersed
attapulgite binder.
2. Background Art
Zeolites are hydrated metal alumino silicates having the general
formula
where M usually represents a metal of the alkali or alkaline earth
group, n is the valence of the metal M, x varies from 2 to infinity,
depending on the zeolite structure type and y designates the hydrated
status of the zeolite. Most zeolites are three-dimensional crystals
with a crystal size in the range of 0.1 to 30 .mu.m. Heating these
zeolites to high temperatures results in the loss of the water of
hydration, leaving a crystalline structure with channels of molecular
dimensions, offering a high surface area for the adsorption of inorganic
or organic molecules. Adsorption of these molecules is limited by
the size of the zeolite channels. The rate of adsorption is limited
by the laws of diffusion.
One limitation on the utilization of these zeolite crystals is
their extremely fine particle size. Large naturally-formed agglomerates
of these crystals break apart easily. Because the pressure drop
through the bed is prohibitively high, these zeolite crystals cannot
be used in fixed beds for various dynamic applications, such as
drying of natural gas, drying of air, separation of impurities from
a gas stream, separation of liquid product streams and the like.
Therefore, it is desirable to agglomerate these crystals with other
materials to provide an agglomerate mass of the crystals which exhibits
a reduced pressure drop.
To permit the utilization of these molecular sieve crystals, different
types of clays are used as binders including attapulgite, palygorskite,
kaolin, sepiolite, bentonite, montmorillonite and mixtures thereof.
For example, U.S. Pat. No. 2973327 discloses the use of a number
of different types of clays, including attapulgite, as a binder
for molecular sieves. The clay content of the bonded molecular sieve
can vary from as low as 1 percent to as high as 40 percent by weight,
although the preferred range is from about 10 to about 25 percent
by weight.
U.S. Pat. No. 3219590 discloses another molecular sieve blend
comprising a kaolin-type clay and a lignosulfonate which functions
as the binding agent.
Adsorbent materials comprising a type 5A zeolite molecular sieve
and a kaolin clay binder, wherein the kaolin comprise from about
10 to about 40 percent of the composition, are disclosed in U.S.
Pat. No. 5001098.
Molded bodies containing dealuminated zeolite Y and a binder material
are disclosed in U.S. Pat. No. 5316993.
An adsorbent and/or catalyst blended with a binder system comprising
a colloidal metal oxide, an oxide adsorbent and an acid are disclosed
in U.S. Pat. No. 5948726.
An adsorbent for separating gases comprising a binder and a crystalline,
low silica faujasite-type zeolite with a silica to alumina molar
ratio of 1.9 to 2.1 is disclosed in EP 0 940 174 A2. This reference
discloses the blending of a zeolite with a conventional, dense attapulgite
clay binder useful for the separation of gases. The bulk density
of the binder is not disclosed.
Another blend of a conventional, dense attapulgite clay binder
with a zeolite is disclosed in U.S. Pat. No. 5413978. The bulk
density of the attapulgite clay is from about 400 g/l to about 530
g/l.
An abrasion-resistant granular zeolite formed by blending a zeolite
and a binder system is disclosed in U.S. Pat. No. 4420419. See
also U.S. Pat. No. 5292360 which discloses an adsorbent for the
purification of gases comprising a 5A zeolite molecular sieve and
a kaolin clay binder.
One problem with conventionally formed zeolite blends is decreased
diffusion. The larger the diameter of the formed zeolites, the slower
the rate of diffusion of the molecules to be adsorbed. Particularly
in the field of pressure swing adsorption, this effect is highly
adverse to short cycle time and thus to productivity. Enhanced kinetic
values or faster mass transfer rates can result in shorter cycle
time and lower power consumption and thus higher adsorbent productivity.
It has been recognized that a reduction in the particle size of
formed zeolites leads to shorter mass transfer zones and shorter
cycle times. This is based on the assumption that the time needed
for adsorbates to travel through the macropores of the adsorbents
limits the cycle time, i.e. macropore diffusion is the rate limiting
step in these processes. This problem can be improved by adding
pore forming compounds to the zeolite clay blend before the forming
step.
Accordingly it is an object of the invention to disclose a process
for the preparation of molecular sieve adsorbents with enhanced
diffusion rates.
It is a still further object of the invention to disclose a process
for the production of a molecular sieve adsorbent blend which is
especially useful in thermal swing adsorption (TSA) systems and
in pressure swing adsorption (PSA) systems.
It is a still further object of the invention to disclose molecular
sieve adsorbent blends which maintain their physical properties
and diffusion capabilities even with reduced binder percentages.
It is a still further object of the invention to disclose a process
for the production of a molecular sieve adsorbent blend utilizing
highly dispersed attapulgite fibers.
It is a still further object of the invention to disclose a molecular
sieve adsorbent blend comprising a zeolite powder and a highly dispersed
attapulgite binder.
It is a still further object of the invention to disclose a process
for drying a feed stream comprising passing the feed stream over
a molecular sieve adsorbent blend comprising a zeolite and a highly
dispersed attapulgite binder.
It is a still further object of the invention to disclose a process
for the adsorption of carbon dioxide from an air stream comprising
passing that air stream over a molecular sieve adsorbent blend comprising
a zeolite powder and a highly dispersed attapulgite binder.
It is still further object of the invention to disclose a process
for separation of components of a gaseous or liquid feed stream
comprising passing that gaseous or liquid feed stream over a molecular
sieve adsorbent blend comprising a zeolite powder and a highly dispersed
attapulgite binder.
These and other objects are obtained by the process for production,
the process for use and product of the invention disclosed herein.
SUMMARY OF THE INVENTION
The present invention is a process for the production of a molecular
sieve adsorbent blend with improved performance characteristics
comprising preparing a zeolite, preparing an attapulgite binder
containing highly dispersed attapulgite fibers, mixing the zeolite
with the attapulgite binder in an aqueous mixture, forming molecular
sieve adsorbent products from the mixture, and calcining the adsorbent
product to form a molecular sieve adsorbent blend, wherein the tapped
bulk density of the highly dispersed attapulgite fibers, is above
550 g/l as measured according to DIN/ISO 787 and wherein the water
adsorption capacity of the highly dispersed binder is above 35 percent
(w/w).
The present invention is also a molecular sieve adsorbent blend
comprising a zeolite blended with a highly dispersed attapulgite
binder, wherein the tapped bulk density of the highly dispersed
attapulgite binder is above 550 g/l as measured according to DIN/ISO
787 and wherein water adsorption capacity of the highly dispersed
binder is above 35 percent (w/w).
The present invention is also a process for drying a feed stream
comprising passing the feed stream over a molecular sieve adsorbent
blend comprising a zeolite blended with a highly dispersed attapulgite
binder as defined above.
The invention is also a process for the separation of components
of a gaseous or liquid feed stream comprising passing the liquid
feed stream over a molecular sieve adsorbent blend comprising a
zeolite blended with a highly dispersed attapulgite binder as defined
above.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a molecular sieve adsorbent blend formed
from a zeolite blended with a highly dispersed attapulgite binder
and a process for formation of that product. The invention is based
on the discovery that the adsorption rate of a molecular sieve product
is not only dependent upon the size of the formed zeolite particles,
but also the type and characteristics of the binder blended with
the zeolite. It has been surprisingly discovered that the same type
and quantity of zeolite when blended with different binders produces
zeolite blends which exhibit different adsorption characteristics
depending upon the binder that is used. The phrase "adsorption
rate" or "sorption rate" or "mass transfer rate"
means the rate at which an adsorbate loading in a feed stream changes
over a given period of time for a given adsorption separation process.
The prior art suggests that the adsorption rate of a molecular
sieve adsorbent is only a function of the porosity and particle
size of the molecular sieve adsorbent. It has now been surprisingly
discovered that the type of binder that is used to bind the zeolite
crystals also plays a role in the adsorption rate of the zeolite
material.
Adsorbent aggregates or blends are formed by mixing zeolite crystals
with binder materials. Various types of zeolites may be used to
form the adsorbent blend including zeolite A, zeolite X, zeolite
Y, zeolite ZSM-5 zeolite Beta, synthetic mordenite and blends thereof.
These zeolites may be used singly or in mixtures of two or more
zeolites. Zeolites may be present in their alkali or alkaline earth
metal substituted form. The particular type of zeolite present in
the blend depends upon the adsorbate that is to be adsorbed from
the feed stream. For example, when the desired adsorbent is carbon
dioxide in a gas stream, the preferred zeolites include zeolite
X or zeolite LSX. When the adsorption process is for the purification
of gases, notably by pressure swing adsorption (PSA) and temperature
swing adsorption (TSA) methods, the preferred zeolites include zeolite
A or zeolite X.
Binder materials are utilized to bind the individual zeolite crystals
together, to form shaped products and to reduce the pressure drop
during adsorption. However, in the past the binder material has
not enhanced the adsorption capability of the zeolite. In fact,
conventional binder materials have generally reduced the adsorption
capacity of the zeolites. Binder materials which have been utilized
with zeolites in the past include clay minerals, such as kaolin,
palygorskite-type minerals, such as attapulgite, and smectite-type
clay minerals, such as montmorillonite or bentonite. These clay
binders have been used singly or in mixtures of two or more different
types of clay binders.
The inventors have discovered that a particularly useful blend
of zeolites and a clay binder is produced when the clay material
is an attapulgite clay which has been "highly dispersed."
Generally speaking, clay particles, especially attapulgite clay
particles, exist as dense materials with very limited adsorption
capabilities. These conventional clay binder particles are different
in size and shape from the zeolite particles. When blended with
zeolite crystals they tend to occupy space between the zeolite crystals
and may assist in the adsorption by the zeolite material without
increasing the overall adsorption of the zeolite blend.
In particular, attapulgite clay particles, even after mining and
work-up, are naturally formed in the shape of dense bundles of clumped
bristles. The existence of these bundles has been confirmed using
scanning electron microscopy (SEM). These bristles must be separated
or ground to permit their use as binders for zeolite particles.
Without grinding these attapulgite clay particles to a smaller size,
a non-porous layer of attapulgite clay particles is created in the
zeolite blend, preventing or substantially limiting, diffusion of
adsorbates through the blend. The conventional attapulgite clays
that have been utilized in the past are produced by dry grinding
the attapulgite clay. In the conventional process these dry ground
attapulgite clay bundles of bristles are then blended with the zeolite
crystals. However, even after this conventional grinding of the
attapulgite clay bundles, large bundles of attapulgite clay bristles
are still present. When these conventional attapulgite clay bundles
are blended with zeolite and formed into adsorbents, the capability
of the zeolite materials to adsorb the desired adsorbate is not
substantially enhanced.
The applicants' invention utilizes "highly dispersed"
attapulgite clay as the binder material that is blended with the
zeolite powder. The difference between conventional, dense attapulgite
clay bundles and the "highly dispersed" attapulgite clay
particles of the invention can be differentiated readily through
the use of a scanning electron microscopy. Another method to distinguish
between conventional dense attapulgite clay and the "highly
dispersed" attapulgite clay products of the invention is by
the use of tapped bulk density measurement as determined according
to DIN/ISO 787. Dense attapulgite clay binders contain a residual
water content of about 20-25 percent and have a tapped bulk density
of about 400 g/l to about 530 g/l. "Highly dispersed"
attapulgite binders also contain residual water of about 20-25 percent
but have a tapped bulk density of about 550 g/l to about 700 g/l.
Another method to distinguish between conventional dense attapulgite
clay and highly dispersed attapulgite clay products of the invention
is by determining the water adsorption capacity of the attapulgite
clay products. To determine whether the clay binder is "highly
dispersed" the clay binder is fully saturated at 50 percent
relative humidity at 25.degree. C. to the point where an equilibrium
adsorption capacity is achieved. This process may take up to 72
hours. After full hydration of the clay is achieved the clay is
dried at 550.degree. C. for at least two hours. The difference of
the weight between the fully hydrated clay and the dried clay is
the water adsorption capacity. For dense attapulgite clays, the
water adsorption capacity is below 30 percent whereas for the "highly
dispersed" attapulgite clay, the water adsorption capacity
is above 35 percent.
While any process which produces attapulgite fibers which are "highly
dispersed" as defined above is within the scope of the invention,
one preferred process is disclosed in U.S. Pat. No. 6130179 the
contents of which are incorporated by reference into this application.
This patent fails to disclose or suggest the use of this highly
dispersed attapulgite clay with zeolite. The process of U.S. Pat.
No. 6130179 utilizes a dispersant which disperses the individual
attapulgite particles in water such that they remain in suspension
even after other materials, including other clay and mineral species,
are removed from that solution. Once the "highly dispersed"
attapulgite clay is prepared, it is ready for use in the production
of the molecular sieve adsorbent product of the invention.
Generally the process to produce the molecular sieve adsorbent
blend product with improved performance characteristics according
to the invention is as follows:
prepare the zeolite material,
prepare an attapulgite binder comprising highly dispersed attapulgite
fibers,
mix the zeolite with the attapulgite binder in an aqueous mixture,
form an uncalcined material from the mixture, and
calcine the material to form the molecular sieve adsorbent blend
product of the invention.
Once the appropriate zeolite material is chosen for a given application,
it is mixed with the highly dispersed attapulgite binder in the
presence of water. The zeolite powder and the highly dispersed attapulgite
binder are blended together with water. The amount of highly dispersed
attapulgite binder that is utilized can range from 5 to about 30
percent by weight, preferably from about 5 to about 20 percent and
most preferably in the range of about 10 percent of the blend. Conventional
mixtures of zeolite and non-highly dispersed attapulgite clay binders
utilize about 20 percent or more attapulgite clay. Sufficient water
is retained in or added to the mixture to make a formable mixture,
i.e., one that can be easily extruded.
The mixture is blended using a conventional blending device, such
as a conventional mixer, until a mass of suitable viscosity for
forming is obtained. The blended mixture is then formed into the
appropriate shaped product, for example, by extrusion. The products
can be formed in any conventional shape such as beads, pellets,
tablets or other such conventional shaped products. Once the formed
products are produced into the appropriate shape, they are calcined,
preferably at about 600.degree. C., for about 30 minutes to 2 hours.
In an optional preferred embodiment, a pore forming agent may be
added to the zeolite/attapulgite clay mixture during the mixing
step to enhance the total pore volume of the end product. Among
the acceptable pore forming agents are fibers, including rayon,
nylon, sisal, flax and the like and organic polymers, including
corn starch, starch derivatives, lignosulfonates, polyacrylamide,
polyacrylic acid, cellulose, cellulose derivatives and the like.
The amount of the pore forming agent that may be added is from about
2 to about 15 percent, by weight.
Products produced by the process of the invention show improved
adsorption rates. The adsorption rate can be determined using several
different methods. For example, in one preferred process, the adsorbent
product produced according to the invention can be tested to determine
the time necessary to achieve 95 percent of the maximum adsorption
capacity of the material. The shorter the time to achieve this value,
the faster the adsorption rate.
In another process to determine the adsorption rate of the molecular
sieve adsorbent blend of the invention, the amount of the adsorbed
product that has been adsorbed over a given period of time can be
determined.
In a further process of comparison of adsorption, the mass transfer
zone of the blend of the invention can be compared to that of a
conventional blend under given conditions. The shorter the mass
transfer zone, the higher the adsorption rate.
Finally, the diffusion rate can be determined directly for certain
gases or liquids. The higher the diffusion rate, the faster the
adsorption rate.
It has been surprisingly discovered that by replacing a conventional
attapulgite binder with the same quantity of "highly dispersed"
attapulgite binder of the invention, there is an improved adsorption
rate regardless of which method is used to measure that rate. The
improvement in adsorption rate is at least about 10 percent and
as high as 200 percent compared to products containing conventional
attapulgite clay binders. This improvement is especially important
because of the increased cost of the highly dispersed attapulgite
binder over conventional attapulgite binders.
A further surprising improvement is in the ability of the zeolite
adsorbent blend product to maintain its crush strength even when
the amount of the attapulgite binder that are added to the mixture
is reduced. Generally speaking, the more binder that is present
in the forming process, the better the crush strength for the finished
product. For conventional dense attapulgite binders, this improvement
in the crush strength is dramatic when the percentage of attapulgite
binder within the end product increases from zero to about 20 percent
of the composition. Products made with conventional dense attapulgite
binder of 10 percent or less are not practical as their crush strength
drops below acceptable levels. It has been surprisingly discovered
that a product produced using the highly dispersed attapulgite fibers
of the invention produces an end product with adequate crush strength
even when the quantity of the highly dispersed attapulgite binder
in the end product is as low as 10 percent or less. Further, at
any particular percentage of binder material, the crush strength
of a product produced using the highly dispersed attapulgite fiber
of the invention is higher than for a product made with a conventional
dense attapulgite binder.
It has also been surprisingly discovered that even when lower percentages
of a highly dispersed attapulgite fiber are utilized in an adsorbent
product, the rate of water adsorption increases. This is evidenced
by a reduction in the amount of time that is necessary to achieve
a particular predetermined amount to be adsorbed. This improvement
is at least 10 percent and in many cases as much as 30 percent or
more.
The highly dispersed attapulgite binder can be blended with zeolite
and used for a number of different processes. For example, the blend
of highly dispersed attapulgite clay and zeolite can be used for
drying a feed stream, such as for the removal of water from a gaseous
or liquid ethanol stream. The blend can also be used for the separation
of nitrogen from an air stream. Further, the blend can be used for
the removal of sulfur and oxygen containing compounds from a hydrocarbon
stream. Another use for this blend is for the removal of carbon
monoxide, carbon dioxide and nitrogen from a hydrogen gas stream.
The blend can also be used for the removal of water from a gaseous
or liquid hydrocarbon stream or for the removal of water from a
gaseous or liquid stream of refrigerants. Another use is for the
removal of water and carbon dioxide from air. The adsorbent material
of the invention may also be used for the separation of organic
compound, such as for the separation of n-paraffins from a mixture
of iso-paraffins and n-paraffins or for the conversion of certain
organic compounds. There are a number of other processes for which
this blend of a highly dispersed attapulgite clay and zeolite can
be utilized which would be well known to a person skilled in the
art and which are covered by this invention. |