Note: Descriptions are shown in the official language in which they were submitted.
7~
-- 1 --
CATALYSTS FOR THE OXIDATION AND
AMMOXIDATION OF OLEFINS
BACKGROUND OF THE IN-~ENTION
A. Field of the Invention
This invention relates to oxidation and/or
ammoxidation catalys-ts containing the elements antimony,
uranium, iron, bismuth, and molybdenum in a
catalytically active oxidized state and to a process for
05 preparing such catalysts. In another aspect, this
invention relates to a process for employing such
catalysts to effect the oxidation and/or ammoxidation of
olefins. It is well known that olefins can be oxidized
to oxygenated hydrocarbons such as unsaturated aldehydes
and acids, for example, acrolein and methacrolein1 and
acrylic acid and methacrylic acid. It is also well
known that olefins can be ammoxidized to unsaturated
nitriles such as acrylonitrile and methacrylonitrile.
The value of such oxygenated hydrocarbons and
unsaturated nitriles is generally well recognized, with
acrylonitrile being among the most valuable monomers
available to the polymer industry for producing useful
polymeric products.
B. Description of the Prior Art
Various catalytic processes are known for the
oxidation and/or ammoxidation of olefins. Such
processes commonly react an olefin or an olefin-ammonia
mixture with oxygen in the vapor phase in the presence
; of a catalyst. For the production of acrolein and
acrylonitrile, propylene is the generally used olefin
reactant, and for the production of methacrolein and
methacrylonitrile, isobutylene is the generally used
olefin reactant.
-
-- 2
Many catalysts are disclosed as suitable in
the oxidation and ammoxidation of olefins. One such
catalyst is described in U.S. Patents 4,018,712. This
catalyst is represented by the empirical formula:
05 SbaUbFecBidMeMef g
wherein Me is nickel or cobalt, a is 1 to 10, b is 0.1
to 5, c is 0.1 to 5, d is 0.001 to 0.1, e is 0.001 to
0.1, f is 0 to 0.1, and g is a number taken to satisfy
the valences of the quantities of Sb, U, Fe, I, and Mo,
including Ni and Co if present, in the oxidation states
in which they exist in the catalyst.
Although the yield and selectivity of the
above-described catalysts are generally satisfactory,
the commercial utility of a catalyst system is highly
dependent upon the cost of the system, the conversion of
the reactant(s), the yield of the desired product(s),
and the stability of the catalyst during operation. In
many cases, a reduction in the cost of a catalyst system
on the order of a few cents per pound or a small percent
increase in the yield of the desired product represents
a tremendous commercial economical advantage. And since
it is well known that the economics of acrylonitrile
manufacture dictate increasingly higher yields and
selectivity of conversion of reactants to acrylonitrile
in order to minimize the difficulties attending the
purification of the product and handling of large
recycle streams, research efforts are continually being
made to define new or improved catalyst systems and
methods and processes of making new and old catalyst
systems to reduce the cost and/or upgrade the activity
and selectivity of such catalyst systems. The discovery
of the improved catalysts of the present invention is
therefore believed to be a decided advance in the state
of the art.
SUMMARY OF THE INTENTION
It is the object of this invention to provide
a stabilized catalyst containing the elements antimony,
.~ .
z~
-- 3 --
uranium, iron, bismuth, and molybdenum in a
catalytically active oxidized state useful in the
preparation of unsaturated nitriles by ammoxidation of
olefins, characterized by high activity and selectivity
05 to the nitriles.
Another object of this invention is to provide
a catalyst which is useful for the oxidation of olefins
to the corresponding unsaturated aldehyde.
A further object of this invention is to
provide an improved process for the preparation of a
catalyst containing oxygen, antimony, uranium, iron,
bismuth, and molybdenum.
Yet another object of this invention is to
provide an ammoxidation process which employs such a
catalyst.
To achieve these and other objects which will
become apparent from the accompanying description and
claims, a catalyst is provided which con-tains the
elements antimony, uranium, iron, bismuth, and
molybdenum in a catalytically active oxidized state
represented by the empirical formula:
SbaUbFecBidMe f
wherein a is 1 to 10, b is 0.1 to 5, c is 0.1 to 5, d is
0.001 to 0.1, e is 0.001 to 0.2, f is a number taken to
satisfy the valence requi.rements of Sb, U, Fe, Bi, and
Mo in the oxidation states in which they exist in the
catalyst. According to the present invention, such a
catalyst is prepared by
(a) preparing a hydrated mixed oxides
component containing antimony, uranium,
iron, and bismuth by the steps of
(i) forming a mixture of oxides or
nitrates of bismuth and uranium and
an oxide of antimony in nitric
acid,
(ii) heating the mixed oxides mixture at
a temperature and for a time
sufficient to induce formation of
crystalline oxides of antimony,
,,
/
~1~123~
--4--
(iii) adding an aqueous solution of ferric
nitrate to the mixed oxides mixture,
(iv) adjusting the pH of the mixed oxides
mixture to about 8, thereby forming a
hydrated mixed oxide precipitate in an
aqueous phase, and
(v) separating the hydrated mixed oxides
from the aqueous phase
(b) forming an aqueous slurry of the hydrated mixed
oxides component;
(c) adjusting the pH of the hydrated mixed
oxides component slurry to about 9;
(d) adding a molybdate to the hydrated mixed
oxides component slurry;
(e) adjusting the pH of the hydrated mixed
oxides component - molybdate component
slurry to about ~-9;
(f) forming the hydrated mixed oxides
component - molybdate component slurry
into dry particles; and
(g) calcining the dry particles to form the
active catalyst.
In accordance with another embodiment of the present
invention, there is provided a process for the production of
acrylonitrile which comprises reacting at an elevated tempera-
ture in the vapcr phase propylene, ammonia, and molecular
oxygen in the presence of a catalyst as defined above.
In accordance with yet another embodiment of the pre-
sent invention, there is provided a process for preparing a
catalyst containing antimony, uranium, iron, bismuth, and molyb-
denum in a catalytically active oxidized state represented by
the empirical formula:
SbaubFecBidM~eof
12~
-4a-
wherPin a is 1 to 10, b is 0.1 to 5, c is 0.1 to 5, d is 0.001
to 0.1, e is 0.001 to 0.2, f is a number taken to satisfy the
valence requirements of Sb, U, Fe, Bi, and Mo in the oxidation
states in which they exist in the catalyst, said process com-
prising the steps of:
(a) preparing a hydrated mixed oxides component
containing antimony, uranium, iron, and
bismuth by the steps of
(i) forming a mixture of oxides or nitrates
of bismuth and uranium and an oxide of
antimony in nitric acid,
(ii) heating the mixed oxides mixture at a
temperature and for a time sufficient
to induce formation of crystalline oxides
: 15 of antimony
(iii) adding an aqueous solution of ferric
nitrate to the mixed oxides mixture,
(iv) adjusting the pH of the mixed oxides
mixture to about I, thereby forming a
hydrated mixed oxiae precipitate in an
aqueous phase, and
(v3 separating the hydrated mixed oxides
from the aqueous phase
(b) forming an aqueous slurry of the hydrated mixed
oxides component;
(c) adjusting the pH of the hydrated mixed
oxides component slurry to about 9;
(d) adding a molybdate to the hydrated mixed
oxides component slurry;
(e) adjusting the pH of the hydrated mixed
oxides component - molybdate component
slurry to about 8-9;
l~lZ~7~
-4b-
(f) forming the hydrated mixed oxides
component - molybdate component slurry
into dry particles; and
(g) calcining the dry particles to form the
active catalyst.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with a preferred embodiment of this
invention, a catalyst containing antimony, uranium, iron, bis-
muth, and molybdenum, in a catalytically active oxidized state
useEul for the oxidation and/or ammoxidation of olefins is
represented by the empirical formula:
SbaUbFeCBidMeO~
where a is 1 to 10, b is 0.1 to 5, c is 0.1 to 5, d is 0.001 to
0.1, e is 0.001 to 0O2~ f is a number taken to satisfy the
valence requirements of Sb, U, Fe, Bi, and Mo in the oxidation
states in which they exist in the catalyst The catalysts are
prepared by an improved process which comprises:
(a) preparing a hydrated mixed oxides component
containing antimony, uranium, iron, and
bismuth by the steps of
~237~Z
_ 5
(i) forming a mixture of oxides or
nitrates of bismuth and uranium and
an oxide of antimony in nitric
acid,
05 (ii) heating the mixed oxides mixture at
a temperature and for a time
sufficient to induce formation of
: crystalline oxides of antimony,
(iii) adding an aqueous solution of
ferric nitrate to the mixed oxides
mixture,
(iv) adjusting the pH of the mixed
oxides mixture to about 8, thereby
forming a hydrated mixed oxide
precipitate in an aqueous phase,
(v) separating the hydrated mixed
oxides from the mixed oxides
mixture, and washing occluded
impurities from the hydrated mixed
oxides;
(b) forming an aqueous slurry of the hydrated
mixed oxides component;
(c) adjusting the pH of the hydrated mixed
oxides component slurry Jo about 9;
(d) adding a molybdate to the hydrated mixed
oxides component slurry;
: (e) adjusting the pH of the hydrated mixed
oxides component - molybdate component
slurry to about 8-9;
(f) forming the hydrated mixed oxides
component - molybdate component slurry
into dry particles; and
(g) calcining the dry particles to form the
active catalyst.
The catalyst of the present invention is most
desirably prepared as follows. A hydrated mixed oxides
component containing antimony, uranium, iron, and
bismuth is intimately m.ixed with a molybdate component,
e.g., ferric molybdate, ammonia molybdate (the
.~
~2~
-- -- 6
preparation of each of these components being described
below). The mixing of the components is accomplished in
an aqueous slurry at a pH of about 9. Specifically, the
hydrated mixed oxides component is first slurried in
05 water at the prescribed pH. A catalyst support may be
added, if desired, along with the hydrated mixed oxides
component. In either case, whether a support is present
or absent, a molybdate is then added to the slurry. The
resultant slurry is ball milled for about 18 hours or
until the solid particles are reduced to a size less
than 10 microns in diameter. Thereafter, the pH of the
slurry is adjusted, if necessary to about 8-9.
At this point, the intimately mixed slurry is
heated to remove the bulk of the aqueous phase. The
concentrated slurry contains a certain amount of water
and it is desirable to remove this water by some form of
drying process to form a dry catalyst precursor. This
can take the form of a simple oven drying process in
which the water-containing solid phase is subjected to a
temperature that is sufficiently high to vaporize the
water and completely dry the solid phase.
An alternate drying process which may be
employed is the so-called spray-drying process. In this
process, which is preferred for use in the present
invention, water-containing solid phase particles are
sprayed into contact with hot gas (usually air so as to
vaporize the water. The drying is controlled by the
temperature of the gas and the distance the particles
travel in contact with the gas. It is generally
desirable to adjust these parame-ters to avoid too rapid
drying as this results in a tendency to form dried skins
on the partially dried particles of the solid phase
which are subsequently ruptured as water occluded within
the particles vaporizes and attempts to escape. At the
same time, it is desirable to provide the catalyst in a
form having as little occluded water as possible.
Therefore, where a fluidized bed reactor is to be used
and microspheroidal particles are desired, it is
advisable to choose the conditions of spray-drying with
J
~2~7~
-- 7
a view to achieving substantial complete drying without
particle rupture.
Following the drying operation, the catalyst
precursor is calcined to form the active catalyst. The
05 calcination is usually conducted in air at essentially
atmospheric pressure and at a temperature of about 500C
to about 1150C, preferably from about 750C to about
900C. The time to complete the calcination can vary
and will depend upon the temperature employed. In
general -the time can be anything up to 24 hours, but for
most purposes, a time period from about 1 hour to about
3 hours at the designated temperatures is sufficient.
The catalyst can be employed without a support
and will display excellent activity. However, in some
applications, it may be advantageous to include in the
catalyst a support material which functions by providing
a large surface area for the catalyst and by creating a
harder and more durable catalyst for use in the highly
abrasive environment of a fluidized bed reactor. This
support material can be any of those commonly proposed
for such use, such as, for example, silica, zirconia,
alumina, titania, antimony pentoxide sol, or other oxide
substrates. From the point of view of availability,
cost, and performance, silica is usually a satisfactory
support material and is preferably in the form of silica
sol for easy dispersion.
The proportions in which the components of the
supported catalysts are present can vary widely, but is
usually preferred that the support provides from about
10% to about 90~ and more preferably about 35% to about
65% by weight of the total combined weight oE the
catalyst and the support. To incorporate a support into
the catalyst, the support material is preferably
slurried along with the hydrated mixed oxide component
in water at a pH of 9 while maintaining slurry fluidity.
~lZ~7~
--8--
As previously noted, the hydrated mixed oxides
component contains antimony, uranium, iron, and bismuth.
It is prepared by mixing the oxides or nitrates of
bismuth and uranium and an oxide of antimony (usually
antimony trioxide) with nitric acid. A most referred feature
of the instant invention is the heating of the antimony
trioxide in the nitric acid. By so doing, the initially
amorphous antimony trioxide is converted to crystalline
oxides of ant ny. In Addison, preferably at least a po on ox
the antimony trioxide is converted to higher oxidation
states such as antimony tetroxide and antimony
pentoxide.
The time required to induce the formation of
the desired crystalline oxides of antimony can vary and
15 - will depend, at least in part, on the temperature
employed. Generally, a time period of about 2 hours to
about 6 hours at temperatures from about 90C to about
llO C, preferably at least lOO C, is sufficient.
After the heating period is completed, an
aqueous solution of ferric nitrate ~Fe(N03)3.9H2O~ is
added to the mixed oxides mixture, optionally having
been cooled to ambient temperatures prior to the ferric
nitrate addition. The pH of the resultant mixture is
adjusted to about 8 using aqueous ammonia. The
resulting hydrated mixed oxides precipitate is then
separated from the aqueous phase and thoroughly washed
with slightly alkaline water (pH 8) to remove
substantially all occluded impurities, most notably
ammonium nitrate.
The molybdate may be introduced as any compound
which does not interfere with catalysis or neutralize
the catalyst. Ferric molybdate and ammonium molybdate
have been successfully employed to introduce the
molybdate. Ammonium molybdate is preferred, being the
simplest to prepare (from molybdenum trioxide and
aqueous ammonia). Ferric molybdate may be prepared by
combining stoichiometric amounts of aqueous solutions of
., .
3~
9 _
ammonia molybdate (prepared by dissolving molybdenum
trioxide in aqueous ammonia) and ferric nitrate. wince
the ammonia molybdate is essentially neutral with
respect to pH and the Eerric nitrate solution is highly
05 acidic, the resulting aqueous ferric molybdate slurry or
mixture will also be highly acidic, that is to say, it
will have a pH less than about 3. Indeed, it has been
found that in preparing ferric molybdate, it is critical
that the pH of the mixture exists within the stated
value range. Otherwise, the resultant catalyst exhibits
decreased activity and selectivity toward the desired
product(s). Upon mixing the two aqueous solutions, an
initial light brown precipitate forms. It has been
found to be critical to the performance of the catalyst
that this initial brown precipitate is converted to a
final bright yellow precipitate. This conversion is
readily accomplished by heating the mixture at a
temperature (usually 95-100C) and for a time sufficient
to effect such conversion (usually 1-2 hours). The
bright yellow ferric molybdate precipitate is separated
from the aqueous phase of the mixture and thoroughly
washed to remove occluded impurities, again most notably
ammonium nitrate.
As previously stated, catalyst according to
this invention is that represented by the empirical
formula:
SbaUbFecBidMe f
where a is 1 to 10, b is 0.1 to 5, c is 0.1 to 5, d is
0.001 to 0.1, e is 0.001 to 0.2, f is a number taken to
satisfy the valence requirements of Sb~ U, Fe, Bi, and
Mo in the oxidation states in which they exist in the
catalyst. In more preferred embodiments of such
catalysts, a is 1 to 5, b is 0.1 to 1, c is 0.1 to 1, d
is 0.01 to 0.05, e is 0.01 to 0.1.
The catalyst preparation of this invention
yields an improved catalyst that exhibits exceptional
utility in the production of nitriles from olefins.
Z37~
-- 10 --
Olefins suitable for use in this invention include those
characterized by having at least one methyl group
attached to a trigonal carbon atom. Nonlimiting
representatives of such olefins include propylene,
05 isobutylene, 2-methyl-1-pentene, 1,4-hexadiene, and the
like. Of particular importance is the production of
acrylonitrile from propylene and in the discussion which
follows, specific reference is made to that process
although it should be understood that the described
catalyst is also useful for ammoxidation of other
suitable olefins and for oxidation of such olefins to
aldehydes and acids.
In the most frequently used ammoxidation
processes, a mixture of olefin, ammonia, and oxygen (or
air) is fed into a reactor and through a bed of catalyst
particles at elevated temperatures. Such temperatures
are usually in the range of about 400C to about 550C,
and preferably about 425C to about 500C, and the
pressure is from about 1 atmosphere to about 6
atmospheres (100 kPa to about 600 kPa). The ammonia and
olefin are required stoichiometrically in equimolar
amounts, but it is usually necessary to operate with a
molar ratio of ammonia to olefin in excess of 1 to
reduce the incidence of side reactions. Likewise, the
stoichiometric oxygen requirement is 1.5 times the molar
amoun-t of olefin. The feed mixture is commonly
introduced into the catalyst bed at a W/F (defined as
the weight of the catalyst in grams divided by the flow
of reactant stream in ml/sec. at standard temperature
and pressure) in the range of about 2 g-sec/ml to about
15 g-sec/ml, preferably from about 4 g-sec/ml to about
10 g-sec/ml.
The ammoxidation reaction is exothermic and
for convenience in heat distribution and removal, the
catalyst bed is desirably fluidized. However, fixed
catalyst beds may also be employed with alternative heat
removal means such as cooling coils within the bed.
it
37~
-- 11 --
The catalyst as prepared by the process of
this invention is particularly well adapted for use in
such a process in that improved yields of and
selectivities to the desired product(s) are experiences
05 due to the unique and novel preparation procedures
employed herein.
The following examples illustrating the best
presently-known methods of practicing this invention are
described in order to facilitate a clear understanding
of the invention. It should be understood, however,
that the expositions of the application of the
invention, while indicating preferred embodiments, are
given by way of illustration only and are not to be
construed as limiting the invention since various
changes and modifications within the spirit of the
invention will become apparent to those skilled in the
art from this description.
As used herein, the following terms are
defined in the following manner:
1. 'IW/F'' is defined as the weight of the
catalyst in grams divided by the flow
rate of the reactant stream in ml/sec.
measured at STP, the units being g-sec/ml.
2. "Propylene (C3H6) conversion" is defined as:
;mols C3H6 in feed - mols C3H6 in effluent x 100
C3 6 eed
; 3. "Acrylonitrile (AN) selectivity" is defined as:
mols AN in effluent x 100
mols C3H6 converted
4. "Acrylonitrile (AN) yield" is defined as:
mols AN formed x 100
mols C3H6 feed
In the following paragraphs, the catalysts of
the examples (approximately 30g in each case), were
evaluated in a fluidized bed reaction vessel having an
inside diameter of about 13mm to determine acrylonitrile
selectively and yield and propylene conversion. A
'`-'';i
~123~7~
- 12 -
reactant mixture of 17-17.8 volume percent 2' 7.6-8.3
volume percent propylene (C3H6), 8-9 volume percent
ammonia (NH3), and the balance helium was passed upward
through the catalyst bed at a rate sufficient to give
05 the value of W/F desired. The temperature was
maintained between about 425C and about 500C
(preferred temperatures) and the pressure at about 200 x
102 kPa (29 psia) to about 2.50 x 102 kPa (36.3 psia)
unless otherwise noted.
EXAMPLE 1
A catalyst of the composition:
1-86 o-33Feo.67Bi0.020Mo0 0400f-45% Si02 was
prepared in the following manner.
(a) _ydrated Mixed Oxides
(sbl.86u0~33Feo~66Bio 020of-xH2o) Bismuth
trioxide (Bi203, 21.1g, 0.045 mol) was added,
with stirring, to 1830.0g of 70% nitric acid
contained in a 4-liter beaker. The solution
was heated to about 60C and 420.6g (0.50 mol)
of triuranium octoxide (U3O8) was added over a
period of 5 to 10 minutes. The generation and
evolution of nitrogen oxides were observed
during this period. When the generation of
; nitrogen oxides subsided, the solution was
diluted with 600 ml of water and 1224.0g (4.20
mols) of antimony trioxide (Sb2O3) was added
to the solution. The resultant mixture was
covered and heated to 100-105C and maintained
at this temperature for a period of time
sufficient to convert the amorphous antimony
trioxide to crystalline oxides of antimony,
usually 2, 4, or 5-6 hours (designated in the
active catalyst as A, B, and C, respectively),
and thereafter cooled to ambient temperatures.
The cooled mixture was transferred to a
9-liter glass jar and a solution of 1210.5g
(3.00 mols) of ferric nitrate nonahydrate
.; ,.
,,
LZ~
- 13 -
[Fe(NO3)3.9H2O] in 2,000 ml of water was added.
The pH of the mixture was adjusted to 8 with
about 3600 ml of a solution of aqueous ammonia
(28%) [57% ammonia hydroxide (NH4OH)] diluted
05 with an equal volume of water. The mixture was
divided into 3 equal portions and suction
filtered. Each filter cake of precipitate was
washed with 6 liters oE water, the pH of which
was adjusted to 8 by adding aqueous ammonia,
to remove ammonia nitrate formed during the
precipitation as well as other occluded
impurities.
(b) Ferric Molybdate [Fe2(MoO4)3] - A solution of
26.0g (0.18 mol) of molybdenum trioxide (MoO3)
in 27 ml of 28% aqueous ammonia and 75 ml of
water was added to a stirred solution of 48.6g
(0.12 mol) of ferric nitrate nonahydrate
[Fe(NO3)3..9H2O] in 450 ml of water at a rate
sufficient to prevent gel formation. The pH
of the mixture was 2-3. The mixture was
heated at 95-100C until the initial light
brown precipitate turned bright yellow
(approximately 1-2 hours). The vessel was
covered during the heating period to minimize
loss of water. The aqueous phase was decanted
from the precipitate, which was then
reslurried in 500 ml of water, suction
filtered, and washed with an additional 500 ml
of water.
(c) Catalyst - To a 12-liter stainless steel
container equipped with a mechanical stirrer
was added 400.0g of 40~ aqueous silica sol
(Nalocag 2327) and 400 ml of water. The pH
was adjusted to 9 by adding a few drops of
aqueous ammonia. The hydrated mixed oxide
from Procedure (a) above was slurried into
the silica sol in portions, alternating with
additional portions of silica sol to maintain
-~r7~
- 14 -
the fluidity of the slurry until a total of
4254.0g of silica was added. The ferric
molybdate from Procedure (b) above was then
added to the hydrated mixed oxide-silica sol
05 slurry (pH 9) and the pH adjusted to 9, if
necessary, by the addition of aqueous ammonia.
The slurry was transferred to a ball jar and
ball milled for about 18 hours, or until the
solid particles were reduced to a size less
than 10 microns. The ball milled slurry was
transferred to a stainless steel pot and
concentrated until a viscosity suitable for
spray-drying was obtained. At this point the
volume of the slurry was approximately 7
liters. The pH was adjusted to 8, if
necessary. The slurry was then spray dried at
a temperature of about 150C. The dried
particles were calcined at 850C for 1 hour in
air to produce the active catalyst supported
on 45% by weight silica.
EXAMPLE 2
To demonstrate the improvement of the catalyst
composition as that of the present invention a catalyst
having the same composition as that in Example 1 was
prepared according to the procedure described in Example
X of U.S. Patent 4,018,712.
EXAMPLE 3
A catalyst of the composition:
2 25Mo 5FeO~sBiO 02MO 04 50% Sio2 was
prepared in the following manner:
2.8 g. of Bi2O3 was added to 305 g. of 70%
HNO3 in a 21 stirred vessel. The mixture was
heated to 80C and 84 g. of U3O8 was added over a
period of about 5 minutes. The temperature was
raised to 90C and maintained at this
temperature for 20 minutes to dissolve all the
, .i .~
-15-
U308. Nitrogen oxides were generated during
this period.
150 ml of water was then added and the
temperature was dropped to 80C. 196.8 g. of
S Sb203`was th`en added. The mixture was
digested at 100C for 2 hours.
The mixture was cooled to room temperature and
a solution of 121.2 g. of Fe(N03)3 9H20 in 1000
ml of water was added. The mixture was
transferred to a 41 beaker.- Its pH was
adjusted to 5 with 575 ml of solution of 1:1
mixture of NH40H and water in 15 minutes. The
mixture was allowed to stand for 1 hour and pH
was further increased to 8 with 25 ml
additional 1:1 NH40H solution.
The mixture was allowed to stand overnight. It
was filtered and washed 6 times with 500 ml
portions of water having its pH adjusted to 8
with NH40H-
The filter cake was slurried into 836 g. of
Nalco silica sol 2327 and tha pH was adjusted
to 9 by the addition of 1:1 NH40H solution. An
ammonium molybdate solution prepared by
dissolving 3.46 g. of MoO3 in a mixture of 3.6
ml of NH40H and 10 ml of water was then added.
The pH was again adjusted to 9 with NH40H
solution.
The slurry was transferred to a jar and ball
milled for 18 hours. It was then c'oncentrated
to a volume of about 1800 ml. The slurry,
which had a pH of 8.5, was spray dried at a
temperature of 120C using an air pressure of
15 prig. The spray dried material was calcined
at 850 C for 1.25 hours to produce about 650 g.
of catalyst.
EXhMPLE 4
The catalysts from Examples 1 - 3 were
separately charged to reaction vessels
1~23~
described above and used to convert propylene
to acrylonitrile (AN)o
The parameters and results are shown in Table 1.
TABLE 1
05 Catalyst l-A- l-B- l-C3 24 3
Reaction Temp., oC 460 455 455 450 463
Pressure, X102 kPa 2.19 2.25 2.25 2.15 1.92
Feed., Volume %
C3~6 8.0 8.0 8.5 8.0
NH3 8.4 8.4 8.4 8.5 8.5
2 17.5 17.5 17.5 17.4 17.5
He 66.1 66.1 66.1 65.6 66.1
W/F, g-sec/ml 5.0 4.5 4.5 5.0 4
C3H6 Conv., % 97.1 96.9 9677 96.6 96.0
AN
Selec. 76.8 78.1 77.7 76.5 81.0
Yield, 74.6 75.7 7501 73.9 77.8
1 Sb2O3 in the hydrated mixed oxides was heated
2 hours in nitric acid.
2 Sb2O3 in the hydrated mixed oxides was heated
4 hours in nitxic acid.
3 Sb2O3 in the hydrated mixed oxides was heated
5.5 hours in nitric acid.
4 Catalyst prepared according to the procedure
described in Example X of U.S. Patent
4,018,712, except that the catalyst was
supported on 45% silica.
As can be seen, each of the catalysts prepared
according to the improved procedure of the present
invention gave higher propylene conversion and
acrylonitrile selectivity and yield, thereby
demonstrating the improvement exhibited by the catalysts
of the present invention.
Thus, it is apparent that there has been
provided in accordance with the present invention, a
1~23~
- 17 -
catalyst and a process for using same that full satisfy
the objects and advantages set forth hereinabove. While
the invention has been described with respect to various
specific examples and embodiments thereof, it is
05 understood that the invention is not limited thereto and
that many alternatives, modifications, and variations
will be apparent to those skilled in the art in light of
the foregoing description. Accordingly, it is intended
to embrace all such alternatives, modifications, and
variations as fall within the spirit and broad scope of
the invention.
....
I,, I.
