Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
13618~
-1- C-20-19 1269
AMMOXIDATIO~ CATAIYST
BACKGROUND OF THE INVENTION
This invention relate~s to ammoxidation catalysts
containing the elements cerium or niobium, tellurium,
molybdenum oxygen and a component selected from lanthanum,
the rare earths, thorium zirconi~m, tantalum, and ti-
tanium and optionally a componenit selected from chromium,
gallium, iron, phosphorous, tung3ten, tin, and bismuth,
and to a method o preparing such catalysts. In ano~her
aspect, this invention relates to a process employing such
catalysts.
It is well known that olefins can be ammoxi-
dized to unsaturated nitriles such as acrylonitrile and
methacrylonitrile. The value of such unsaturated nitriles
is generally well recognized with acrylonitrile being among ,
the most valuable monomers available to the polymer indus-
try for producing useful polymeric products.
Various catalytic processes are known for the
ammoxidation of olefins. Such processes commonly react
an olefin-ammonia mixture with oxygen in the vapor phase
in the presence of a catalyst. For the production o
acrolein and acrylonitrile, propylene is the generally
~7
8.2 3
C-20-19-1269
--2--
used olefin reactant and ~or the production of methacro-
lein and methacrylonitrile, isobutylene is the generally
used olefin reactant.
In U. S. Patent and Trademark Of~ice Defensive
Publication No. 688,343 ~Ofcial Gazette, Dec. 10, 1968,
857(2), 368), there is described an ammoxidation catalyst
comprising oxides of molybdenum, bismuth, and at lea~t
one of niobium and tantalum. Also, in Defensive Publica-
tion No. 782,452 (Official Gaze~te, July 15, 1969, 864(3),
730) there is described an oxidation catalyst comprising
a tellurium compound, an oxide of molybdenum and an oxide
of niobium or tantalum.
It is well known that the e~onomics of acrylo-
nitrile manufacture dictate increasingly higher yields and
.selectivity of conversion of the reactants to acryloni-
trile in order to minimize the difficulties attending puri-
fication of the product and handling o~ large recycle
streams. Moreover, it is known that prior art catalysts
frequently produce relatively large quantities of unde-
sired oxygen-containing by-products such as CO2, acrolein
and/or acrylic acid which must be removed in ~urification
of the acrylonitrile.
SUMMARY OF THE lNVENTION
.
It is an object of this invention to provide
a catalyst which gives surprisingly higher yieIds and
selectivity of conversion of propylene, ammonia, and air
to acrylonitrile than do prior art catalysts.
It is a further object to provide a catalyst
which minimizes the production of oxygenated by-products
of acrylonitrile, such as CO2, acrolein, acrylic acid,
and the like.
Still another object is to provide a catalyst
which exhibits substantially its full activity immediately
upon startup of an ammoxidation process, i.e., which re-
quires no break-in period under ammoxidation conditions
in order to exhibit its full e~ficiency in terms o~ ac-
tlvity and selectivity.
C-20-19-1269
--3--
A further object of this invention is to pro-
vide a process for manufacture of such a catalyst.
To achieve these and other objects which will
become apparent, a catalyst is provided having the empiri-
5 cal formula XaYbZcTedMloOx~ wherein a is from 0.5 to 30,such as 1 to 10, and more preferably 1 to 5, b is from 1
to 80, preferably 2 to 30, c is from 0 to 50, such as 0
to 10, preferably 0 to 5, d is from 1.5 to 25, such as 2
to 15, and preferably 2 to 5, and x is a number taken to
satisfy the valence requirements of the metals in the oxi-
dation states in which they exist in the catalyst. In
- this formula, X is one or more of Ce, La, a rare earth,
Th, and Zr, Y is one or more of Nb, La, a rare earth, Th,
Zr, Ta, and Ti, and Z is selected from Cr, Ga, Fe, P, W,
Sn, and Bi, provided that at least one of Ce and Nb must
be present. In other wordsJ i~ X i's not Ce then Y must
be Nb, and if Y is not Nb then X must be Ce,
Catalysts according t:o this invention prefer-
ably contaîn both cerium and niobium and are preferably
prepared by preforming a tellurium molybdate (Te2MoO7)
component and a cerium mol~bdate component. These molyb-
date components are then ground and formed into a slurry
to which is added the niobium alld Z metal component(s) in
the form of oxides, salts or acids.
I~ cerium is absent, catalysts according to
this invention are preferably prepared by preorming a
tellurium molybdate (Te2MoO7) component and a component
which is a molybdate of the metal X,
These molybdate components are then ground and
ormed into a slurry to which is added the Y if not nio-
bium and Z metal components in the form o~ oxides, salts,
or acids. The resultant slurry is then further ground
and mixed, a support material is added, if desired, and
the mixture is dried and calcined. Suitable sources of
the catalyst components include, but are not limited to
the oxides, salts, such as the nitra~es, chlorides, oxa-
lates and the like or in some instances acids such as tel-
1 3 ~1~23
C-20-19-126
--4--
luric, niobic and phosphoric acids. In the case of tel-
lurium and molybdenum, or tellurium and tun~sten, these
components may be added as a powdered alloy of the two me-
tals. The slurry, after intimate mixing, is then heated
to remove the bulk of the aqueous phase. The concentrated
slurry contains a certain amount of water and it is de-
sirable to remove this water by some form o~ drying pro-
cess 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 out the solid phase.
An alternate drying process which may be em-
ployed is the so-called spray-drying process in which
water-containing solid phase particles are sprayed into
contact with hot gas (usually air) so as to varporize the
water. The drying is controlled by the temperature o~
the gas and the distance the particles travel in contact
with the gas. It is generally undesirable to adjust these
parameters to achieve too rapid drying as this results in
a tendency to form dried skins on the partially dried par-
ticles of the solid phase which are subsequently ruptured
as water occluded within the particles ~aporizes and at-
tempts to escape. By the same token, it is desirable to
provide the catalyst in a form having as little occluded
water as possible. Therefore, where a fluidized bed re-
actor is to be used and microspheroidal particles are de-
sired, it is advisable to choose the conditions of spray-
drying with a ~iew o~ achie~ing substantially complete
drying without particle rupture.
Following the drying operation, the catalyst
precursor is calcined to form the catalyst. The calcin-
ation process is usually conducted in air at essentially
atmospheric pressure ~md at a temperature of above about
400C, such as from about 450 to about 600C, and pre-
~erably at abou-t 500C. The time to complete the calcin-
ation can be anything up to 10 hours, but ~or most pur-
1 3 6~8~3
C-20-19-1269
--5--
poses, the calcination need take only from about 1 to 2
hours, preferably about 2 hours at the preferred calcin-
ation temperature of about 500C.
In some applications, it may be advantageous
to include in the catalyst a support material which may
or may not be active catalytically but 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 com-
monly proposed for such use such as, for example, silica,
zirconia, alumina and titania or other oxide substrates.
From the point of view of availability, cost and perform-
ance, silica is usually a satisfactory support material
and is preferably in the form of silica sol for easy dis-
' persion.
The proportions in which the components of the
supported catalyst are present can vary widely but it is
. usually preferred that the support provides from 20 to
80% and most preferably about 40 to 60% by weight of the
total combined weight of the catalyst and the support. To
incorporate a Qupport into the catalyst, the support ma-
terial is preferably added to the slurry containing the
catalytic components discussed above.
The catalyst preparation of the invention yields
a catalyst that is particularly useful in the production
of acr~lonitrile fron propylene and in that 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 olefins and for oxida-
tion of aliphatic olefins to aldehydes and acids.
In the most frequently used ammoxidation pro-
cesses, a mixture of olefin, ammonia and oxygen (or air)
is fed into a reactor and through a bed of catalyst par-
ticles. The reaction temperature is usually in the rangeof 400C to 550C and preferably 410C to 470C, and the
pressure is 1 to 6 atmospheres (1.03 to 6.20 kg/cm2). The
ammonia and olefin are required stoichlometrically in
C-20-19-1269
--6--
equimolar amounts, but it is usually necessary to operate
with a molar ratio of ammonia to olefin in excess of l to
reduce the incidence of side reactions. Likewise, the
stoichiometric oxygen requirement is 1.5 times the molar
amount of olefin but desirably an oxygen to propylene
ratio of 1.6 to 2.4 and preferably 1.9 to 2.0 is employed.
The feed mi~ture is commonly introduced into the catalyst
bed at a W/F (defined as the weight of ~he catalyst in
grams divided by the flow of reactant stream in ml/sec.
at standard temperature and pressure) in the range of
about 2 to about 10, preferably from about 2.5 to about 6.
The ammoxidation reaction is exothermic and
for convenience in heat distribution and removal the cata-
lyst bed is desirably fluidized; however, fixed catalyst
beds may be employed with alternative heat removal means
such as cooling coils within the bed.
The catalyst prepared by the process of the pre-
sent invention is particulrly well adapted for use in
such a process and in what ~ollows its effectiveness is0 demonstrated in the context of ~hat process.
SPECIFIC EMBODIMENTS
As has been stated above, the catalyst of the
invention broadly has the empirical ~ormula XaYbZcTe~olOOx
where a is 0.5 to 30, b is l to 80, c is O to 50, d is
1.5 to 25 and x is a number taken ~o satisfy the valence
requirements of the metals present in the catal~st, op-
tionally dispersed on a finely-di~ided support which rep-
resents from 20 to 80~/o of the supported catalyst weight
and wherein X is one or more of Ce, La, a rare earth, Th,
and Zr~ Y is one or more of Nb, La, a rare earth, Th, Zr,
Ta, and Ti, and Z is selected from Cr, Ga, Fe, P, W, Sn,
and Bi, provided that at least one of Ce and Nb must be
present. In other words, if X is not Ce then Y must be
Nb, and if Y is not Nb then X must be Ce.
As used herein, the term "rare earths" means
the series of elements praseodymium through lutetium of
the Periodic Table of the elements. In the examples that
C-20~ 126g
--7--
are presented below, specific compositions within this
range were prepared and employed as catalysts in the am-
moxidation of propylene to produce acrylonitrile.
As used in the following examples, the follow-
ing terms are defined in the following manner:
1. "W/F'7 is defined as the weight of the catalyst in
grams divided by the flow rate of reactant stream
in ml/sec. measured at S.T.P.
2. "Acrylonitrile (AN) selectivity" is defined as:
Mols AN in effluent X 100%
Mols C3H6 convert~
3. "Acrylonitrile (AN) yield" is defined as:
Mols AN formed X
Mols C3H6 feed
In the following examples, unless otherwise
noted, the catalysts of the examples were evaluated to
determine acrylonitrile selectivity and yield and propy-
lene conversion in a fluidized bed reaction vessel hav-
ing an inside diameter of about 12.8 millimeters. Ap-
pro~imately 17.5 grams of catalyst was used in each casP.
A reactant mi.xture of 17-18 volume % 2' 8.0-0.3 volume /O
propylene (C3H6), 8.5-9~/o volume % NH3 and the balance
hellum was passed upward through the catalyst bed at a
rate sufficient to give the value of W/F shown in the
experimental results for each example. The temperatures
shown in the examples are expressed in degrees Celsius
and the pressures are expressed in kilopascals. As used
in the Examples, the symbol "M" refers to mols/liter and -
unless otherwise specified the solvent is water.
Certain of the catalysts of the following ex-
amples were made using as an ingredient a so-called "nio-
bic acid cake". In each instance this cake is prepared as
follows: Weigh out 108.06 gms of NbCl5 and slowly add
it with stirring to 333 ml of denatured ethanol cooled
to 0C in an ice bath. To this solution add a mixture
of 605 ml water and 61 ml concentrated NH40H. The re-
sultant solution should have a pH about 2. Add concen-
l ~61823
C-20-19-126
--8--
trated NH40H until a pH of 10 i5 reached and allow to
stand two days. Filter and wash the precipitate cake.
The result is a highly hydrated niobic acid cake contain-
ing about 85-90% water.
EXA~PLES
A series of runs was performed using catalysts
containing Ce, Nb, Te and Mo and varying the proportions
of the componen-ts. The performance of the catalyst is
shown in Table I following the description of the prepara-
tion of the catalysts.
Example 1
8-68 g Ce(~O3)3-6H2O was dissolved in 25 ml
H2O. To this was added 33.8 ml of 0.592 M H6TeO6, th2n
144.9 ml of 0.69 M MoO3 in NH40H. Separately, moist nio-
bic acid cake containing 7.97 g o~ niobium was slurriad
into 66 ml silica sol (36.3% SiO2, AS) and this slurry
was added to the first mixture. The resulting mixture
was evaporated with stirring, then dried 16 hrs. at 110C,
then calcined in air for 2 hrs. at 550C. The mass was
sized to 75-180 microns.
Example 2
99 g of oxalic acid was dissolved in 1130 ml
H2O. 700 ml of this solution was used to dissolve 270.16 g
of niobic acid cake (equivalent to 31.42 g Nb2O5). To
one-half oE this solution was added 76 ml 0.527 M H6TeO6,
then 348 ml of 0.574 M MoO3 in NH40H. With stirring,
16.67 g of Ce(N03)3 6H20 in 50 ml H20 was added to this
mixture, followed by 116 ml of silica sol ~40V/o SiO2).
The resulting mixture was Pvaporated with stirring, dried
16 hrs. at 110C, then calcined at 500C in air for 2 hrs.
It was sized to 75-180 microns.
Examp1e 3
The tellurium component of the catalyst was
sequestered with the niobium as follows: 39.4 ml of
0.762 M TeO2 in concentra~ed HCl was added to 80 ml of
denatured alcohol previously cooled in an ice bath. 24.31
g of NbC15 was added slowly, then 500 ml of a solution of
C-20-19-1269
_g _
10 volumes H2O with one volume concentrated NH40H with
vigorous stirring. Further addition of concentrated
NH40H was made to take the pH of the slurry to about 9.
The mix~ure was allowed to stand for 40 hrs., then fil-
tered and washed. 100.07 g of this cake (equivalent to16.71 g dry oxides) did not completely dissolve in 250
ml of 0.771 M oxalic acid. To this slurry was added
109.2 ml of 0.685 M MoO3 in NH40H, 13.02 g Ce(NO3)3 6H2O
in 50 ml H20 and 64.2 ml silica sol. The resulting mix-
ture was evaporated with stirring, dried overnight at
110C,calcined in air at 475C for 2 hrs. The mass was
sized to 75-180 microns.
Example 4
Cerium-molybdenum component: 43.12 g Ce(NO3)3
6H20 was dissolved in H2O. To this was added slowly 219
ml of 0.685 M MoO3 in NH40H. A yellow precipitate formed
and the mixture was kept at 50C or 2 hrs. The cake was
then dried at 110C and calcined at 475C for 2 hrs.
. Tellurium-molybdenum component: 73 ml of 0.685
M MoO3 in NH~OH was added to 186.6 ml of 0.536 M H6TeO6
solution, then the mixture evaporated with stirring, dried
at 110C and calcined at 475C ~or 2 hrs.
The cerium-molybdenum and tellurium-molybdenum
components were ground to less than 54 microns and then
11.40 g of the cerium-molybdenum component, 6.95 g of the
tellurium-molybdenum component and niobic acid cake
(equivalent to 11.96 g Nb2O5) in 200 ml of 0.771 M oxalic
acid solution were charged ~o a ball mill and milled for
16 hrs. 58.6 ml of silica sol was added and the mixture
treated as in the first example with the exception that
the calcination temperature was h75C.
Example 5
104.92 g niobic acid cake (equivalent to 11.96 g
Nb2O5) was dissolved in 250 ml of 8% oxalic acid solution.
To this was added 49.3 ml of 0.608 M H6TeO6, 86.3 ml of
0.695 M MoO3 in NH40H, then 13.02 g Ce(NO3)3'6H2O in 25 ml
of H2O, followed b~ 60 ml silica sol. The mixture was
lB23
C-20-19-1269
-10-
evaporated, dried overnight at 110C, calcined a~ 475C,
then sized 75 to 180 microns.
Example 6
101.37 g of niobic acid cake (equivalent to
11.96 g Nb205) was dissolved in 250 ml of 0.771 M oxalic
acid solution. 55.9 ml of 0.536 M H6TeO6, 112.8 ml of
0.665 M MoO3 in NH40H, then 13.02 g Ce(N03)3 6H20 in 2S
ml H2O and 58 ml silica sol were added. The mixture was
then treated as Example 5, except that calcination was
made at 525C for 2 hrs.
Example 7
A catalyst was prepared by the methods of Ex-
ample 4, except that the cerium-molybdenum component was
used in an amount of cake equivalent to 6.10 g of Ce2Mo3O12;
11.14 g of the tellurium-molybdenum component and niobic
acid cake in 305 ml of 0.771 M oxalic acid (equivalent to
12.78 g Nb205) were used, together with 58 ml silica sol.
Calcination was made at 500C for 2 hrs.
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C-20-19-1269
- 12 -
To illustrate the effect o~ inclusion of the
optional element Z of ~he empirical formula of these
catalysts, the following experiments were performed.
The catalysts of the following examples were evaluated
in the ammoxidation reactor and the results of the
evaluations are presented in Table 2 following Example 17.
Example 8
A chromium oxide component was sequestered with
niobium oxide as follows. 2.23 g of CrC13 6H2O was dis-
solved in 63 ml of denatured ethanol. 20.33 g NbC15 was
slowly added, then 125 ml of a solution of 10 volumes H2O
and one volume concentrated NH40H was slowly added, then
50 ml concentrated NH40H. The mixture was allowed to
stand for 48 hrs; its supernatant liquid was water-white.
It was filtered and washed. 80.85 g of this cake
~equivalent to 9.54 g of dry oxides~ was dissolved in 200
ml o~ 8% oxalic acid solution. To this was added 41.1 ml
o~ 0.608 M H6TeO6, then 89.9 ml 0.695 M MoO3 in NH40H.
10.85 g of Ce(NO3)3 6H2O in S0 ml of H2O was added, then
52.7 ml of silica sol. The mixture was then evaporated
with stirring, dried 16 hrs at 110C, then calcined at
475C for 2 hrs and sized to 75-180 microns.
Example 9
A phosphorous oxide component was sequestered with
niobium oxide as follows. 8.68 g of 85% phosphoric acid
was dissolved in 63 ml of denatured alcohol. To this was
added 20.33 g o NbC15. This solution was hydrolyzed
with NH40H solutions and treated as in Example 16. 34.51 g
of this cake (equivalent to 9.18 g of dry oxi~e!s) was dis-
solved in lS0 ml of 8% oxalic acid solution. To this was
added 49.3 g of 0.608 ~I H6TeO6, 107.9 ml of 0.695 ~I MoO3
ln NH4OH, 13.03 g of Ce(NO3)3 6H2O in 50 ml H2O~ then
58.8 ml silica sol was added and the mixture treated as in
Example S.
#23
C-20-19-1269
Example 10
Chromium and phosphorous oxides were seques~ered
with niobium oxide as follows. 6.66 g CrC13 6H2O and
2.88 g of 85~ H3PO4 were dissolved in ethanol. 13.66 g
NbC15 was added and the mixture hydrolyzed with NH40H
solutions and treated as in Example 16. Ninety percent
of the resulting cake was dissolved in 300 ml of 0.771 M
oxalic acid solution. 55.9 ml of 0.536 M H6TeO6, 109.5 ml
of O.685 M MoO3 in NH40H, ~hen 13.02 ~ Ce~NO3)3 6H20 in
25 ml H2O. 81.7 ml of silica sol was added, then the mix-
ture treated as in Example 8.
Example 11
Iron oxide was sequestered with niobium oxide by
the meth`od of Example 10 using 2.43 g of FeC13 6H2O an`d
21.88 g NbC15. The resulting cake was dissolved in 200
ml of 8.8% oxalic acid solution. 57 ml of 0.527 M
H6TeO6, 108 ml of 0.695 M MoO3 in NH~ H? 13.03 g of
Ce~NO3)3 6H2O in 25 ml of H2O ancl then 62 ml,of silica sol
were added. The mixture was then treated as in Example 8.
Example 12
Example 11 was rep~ated using gallium in the form
of Ga(NO3)3 9H2O in place of iron.
Example 13
11~69 g TeO2, 3.29 g SnO and 7.02 g MoO3 were
milled together for 18 hrs in 20 ml of ethanol. This
mixture ~as dried, calcined one hr at 500C, then reground
and calcined 2 hrs more. After grinding to less than 54
microns, 10.9~ g of this product was used to prepare a
catalyst as follows. 116.31 g of niobic acid cake
~equivalenk to 12.91 g of Nb2O5) was dissolved in 280 ml
of 0.771 M oxalic acid. 16.85 of a cerium-molybdenum
component prepared according to the methods of Example
(equivalent to 6.15 g of Ce2Mo3O12) was slurried into
8 2 3
C-20-19-1269
- 14 -
35 ml H2O. The solution and the slurry were charged to a
ball mill together with the Te-Sn-Mo component and 58 ml
of silica sol. This mixture was milled for 19 hrs then
evaporated, dried 16 hrs at 110C, calcined for 2 hrs at
525 C, then sized 75-180 microns.
Example 14
A cake of a bismuth-molybdenum component was pre-
pared by dissolving 340 g o Bi(NO3)3-5H2o in a solution
of one volume of concentrated HNO3 and one volume H2O.
To this was added slowly a solution of 100 g MoO3 in a
solution of 10 volumes H2O and 1.5 volumes of 58~ NH40H.
After adjusting the pH ~o 3, the mixture was heated with
stirring to 65C where it was kept for 3 hrs. After cool-
ing, the precipitate was filtered and washed with 3000 ml
H2O. 23.34 g of the resulting cake ~equivalent to 5.60 g
of Bi2Mo2Og) and 15.48 g of a cerium-molybdenum component
(equivalent to 5.65 g of Ce3Mo3O12) prepared according to
Example 4 were slurried together in 35 ml H2O with warming.
106.83 g of niobic acid cake (equivalent to 11.86 g of
Nb2O5) was dissolved in 270 ml of 0.771 M oxalic acid. The
solution and the slurry were charged to a ball mill with
6.89 g of tellurium-molybdenum component ~prepared accord-
ing to the methods of Example 13, except that the tin com-
ponent was omitted and the Te:Mo ratio of 2:1) and 58 ml
of silica sol. The mixture was then treated as in Example
13.
Example 15
A cerium-molybdenum component was prepared as or
Example ~. 13.91 g of TeO2, 3.14 g of MoO3 and 5.05 g WO3
and 25 ml of ethanol were charged to a ball mill and the
mixture ball-milled for 18 hrs. The mixture was evaporated
then calcined at 500C for one hr, cooled and ground, then
calcined again for 2 hrs at 500C. ~n amount of the
l ~ 61 823
C-20-19-1269
- 15 -
cerium-molybdenum cake equivalent to 11.40 g of
Ce2Mo3012 was slurTied into H2O and 7.37 g of the
tellurium-molybdenum-tungsten component were charged to -
a ball mill with a solution of niobic acid cake equiva-
lent to 11.59 g of Nb205 in 220 mol of 0.771 M oxalic acid
and 58 ml silica sol. The mixture was milled for 18 hrs
then evaporated with stirring, dried for 16 hrs at 110C,
then calcined at 550C for 2 hrs. The mass was sized to
75-180 microns.
Example 16
82.49 g of niobic acid cake ~equivalent to 11.96 g
of Nb205) was dissolved in 260 ml of 0.771 M oxalic acid
solution. 55.9 ml of 0.536 M H6TeO6~, then 109.5 ml of
0.685 M MoO3 in NH40H was added. Next, a solution of
6.25 g of Pr(N03)3 5H20 and 6.51 g of Ce~N03)3 6H20 in
25 ml H20 was added, followed by 64.3 ml silica sol. The
mixture was then treated as in Example 8.
55.02 g of niobic acid cake ~equivalent to 7.98 g
Nb20s) was dissolved in 260 ml of 0.771 M oxalic acid
solution. 49.01 g of tantalic acid cake ~equivalent to
6.63 g of Ta2O5) made according to the reclpe for niobic
acid cake described above, but using 0.4 mols of TaC15 in
place of the 0.4 mols of NbC15 described therein was
added but did not dissolve completely. 55.9 ml of 0.536
M H6TeO6 was added, followed by 109.5 ml of 0.685 M MoO3
in NH40H, 13.02 g Ce~NO3)3 6H20. 80.4 ml of silica sol
was added, then the mixture treated as in Example 8.
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- 16 -
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C-20-19-1269
- 17 -
To illustrate the effect of omitting one or more
of the essential components of catalysts according to this
invention, the following experiments were performed. The
ammoxidation performance of these catalysts is shown in
Table 3 following Example 22.
Example 18
A niobium-free catalyst was prepared using the
tellurium-molybdenum component and the cerium-molybdenum
components prepared as in Example 4. 11.40 g of the
cerium-molybdenum component and 6.95 g of the tellurium-
molybdenum component with 20 ml of 0.771 M oxalic acid
were ball-milled ~ogether for 1 hr. The mixture thickened
and 40 m~l H20 was added to loosen it. Milling was then
resumed for 16 hrs. 35.5 ml silica sol was added
and the mixture evaporated with stirring, dried overnight
at 110C, then calcined for 2 hrs at 475C.
Examples 19-22
A series of catalysts was prepared based on the
empirical formula Ce2Nb6Te2Mo100x but in which one of the
four metal components was omitted. The catalyst components
were combined as follows in the catalysts in which the
respective components were present. 0.527 moles of
H6TeO6 were added to a solution of Ce(N03)3 6H20, followed
by an oxalic acid solution of niobîc acid cake, then
a . 574 moles of MoO3 in NH40H. Finally, the silica sol
was added. The liquid was then evaporated with stirring
and the material was thoroughly dried at 110C and then
calcined at SOoC for 2 hrs.
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C-~0-l9-1269
-19 -
A series of experiments was run to show the ef-
fect of differing "X" componen~s other than cerium in the
empirical formula of the catalyst. The results are shown
in Table 4 following Example 26.
Example 23
.
94.18 g of niobic acid cake (equivalent to 9.97
g Nb205) was dissolved in 225 ml of 8% oxalic acid solu-
tion and 49.3 ml of 0.608 M H6TeO6, then 107.9 ml of 0.695
M MoO3 in NH40H were added. A solution of 12.51 g of Pr
10 (N03)3 5H20 in 30 ml H20 was added followed by 63.2 ml of
silica sol. The mixture was evaporated with stirring,
dried 16 hrs. at 110C then calcined at 475C for 2 hrs.
It was sized to 75-180 microns.
Example 24
Example 23 was repeated ~xcept that 16.56 g
Th(N03)3'4H20and 68.6 ml silica sol were used.
Example 2S
95.69 g of niobic acid cake (equivalent to
11.96 g Nb205) was dissolved in 300 ml of 0.771 M oxalic
20 acid solution. To this was added 52.8 ml of 0.568
M H6TeO6, then 108.2 ml of 0.693 M MoO3 in NH~OH. 12,45 g
of La(N03)3'5H20 in 25 ml H20 was added followed by 63.7
Nalco silica sol. The mixture was then treated as in Ex-
ample 23.
Example_26
Zirconium oxide was sequestered with niobium
oxide as follows: 10.63 g ZrOC12 8H20 was dissolved in
250 ml of denatured alcohol with warming and slow addition
of 29 ml of concentrated HCl. This solution was stored
30 in a freezer overnight, then 24.31 g of NbC15 was added
followed b~ slow addition of 200 ml o a solution of five
volumes of H20 and one volume concentrated NH40H. 60 ml
of concentrated NH~OH was added to take the pH of the mix-
ture to about 9. The mi~ture was allowed to stand for 72
hours then filtered and washed. This filter cake was par-
tially dissolved in 350 ml of 0.771 M oxalic acid solution,
then 52.7 ml of 0.569 M H6TeO6, 112.8 ml of 0.665 M MoO3
~ :1 6~823
C-20-19-1269
-20
in NH40H, then 82 ml of silica sol were adde~. The mix-
ture was then treated as in Example 23.
I ~ 6~ 823
C-~0-19-1269
-21-
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C-20-19-1269
-22~
A series of experiments was run to shQw the
effect of "Y" components other than niobium in the em-
pirical forumula of the catalyst. The results are shown
în Table 5 following Example 28.
Example 27
Tantalic acid was prepared by dissolving
142.91 g TaC15 in 333 ml ethanol, then adding 666 ml of
a solution of 10 volumes of H2O and one volume of concen-
trated NH~OH. Concentrated NH40H was then added to take
the pH o~ the mixture to about 9. The mixture was al-
lowed to stand for 48 hrs., then filtered and washed.
97.92 g of this cake (equivalent to 13.22 g of Ta205)
was slurried into 67.7 ml of silica sol. 8.68 g of
Ce(NO3~3 6H2O was dissolved in 25 ml H2O, then 33 ml of
lS 0.608 M H6TeO6 and 71.9 ml of 0.695 M MoO3 in NH40H was
added, followed by the slurry of tantalic acid cake in
silica sol. The mixture was then evaporated with stir-
ring, dried for 16 hrs. at 110C and calcined at 475C for
2 hrs. The dried material was finally sized to 75-180
microns.
Example 28
A cake of hydrous titanium oxide was prepared
by dlssolving 31.3 ml of 95% titanium isopropoxide in 100
ml o~ dry isopropyl alcohol. Then 100 ml of a solution of
four volumes H20 and one volume concentrated NH40H was
added slowly to take the pH to about 10. The mixture was
allowed to stand, filtered and washed. 48.23 g of this
cake (equivalent to 7.19 g TiO2) was dissolved in 260 ml
of 0.771 M oxalic acid solution. Then 52.7 ml of 0.569M
H6TeO6, 118.3 ml of 0.634 M MoO3 in NH40H, 13.02 g
Ce(NO3)3 6H20 in 25 ml H20 were added, followed by 58.1
ml silica sol. The mixture was then treated as in Ex-
ample 27.
~ 1 8 2 3
C-20-19-1269
-23-
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