Process for the oxidation of olefins using catalysts contaning antimony

The present invention is a process for the oxidation of olefins to unsaturated aldehydes and acids using a catalyst containing antimony, iron, bismuth, molybdenum plus at least one of nickel, cobalt, magnesium, zinc, cadmium or calcium within certain compositional limits. These catalysts may also contain certain elements that further enhance the desirability of the oxidation process.

SUMMARY OF THE INVENTION 
The invention is in the process for the oxidation of propylene or 
isobutylene to produce the corresponding unsaturated aldehydes and acids 
by contacting the propylene or isobutylene with molecular oxygen in the 
presence of a catalyst at a temperature of about 200.degree. to about 
600.degree. C., the improvement comprising using as the catalyst a 
catalyst of the formula 
EQU Sb.sub.a A.sub.b D.sub.c E.sub.d Fe.sub.f Bi.sub.g Mo.sub.12 O.sub.x 
wherein 
A is an alkali metal, thallium or mixture thereof; 
D is nickel, cobalt, magnesium, manganese, strontium, calcium, zinc, 
cadmium or mixture thereof; 
E is phosphorus, arsenic, boron, tungsten or mixture thereof; 
and wherein 
a is greater than 0 but less than 5; 
b and d are 0-4; 
c is 0.1 to 20; 
f and g are 0.1 to 10; and 
X is the number of oxygens required to satisfy the valence requirements of 
the other elements present. 
This oxidation reaction gives especially desirable results at atmospheric 
or superatmospheric pressure and especially desirable results in the 
oxidation of isobutylene. 
The central aspect of the present invention is the particular catalyst 
employed. The catalysts may be any of the catalysts delimited by the 
formula described above. Preferred as far as the broad compositional 
structure of the catalyst is concerned are those catalysts that contain 
potassium, rubidium, cesium or mixture thereof and those catalysts that 
contain nickel, cobalt or mixture thereof. 
The catalysts of the invention are prepared by techniques that are broadly 
known in the art. These techniques include the coprecipitation of soluble 
salts. More specific information on the preparation of the catalysts is 
given in the Specific Embodiments. 
The catalysts of the invention may be used in the supported or unsupported 
form. Suitable support materials include silica, alumina, Alundum, 
titania, zirconia, silicon carbide and the like. The catalysts may also be 
used in various physical forms. The catalysts can be employed in a 
fixed-bed reactor or a fluid-bed reactor. 
The process for oxidation of propylene or isobutylene is well known in the 
art. Broadly, a mixture of the olefin and molecular oxygen, optionally in 
the presence of steam or other diluent, is contacted with a catalyst at an 
elevated temperature of about 200.degree.-600.degree. C. for a contact 
time sufficient to convert the olefin to the corresponding unsaturated 
aldehyde and acid. Normally, the product from these reactions contains a 
very large portion of the aldehyde and a smaller by-product amount of the 
unsaturated acid. The contact time may vary widely from a few seconds to a 
number of seconds or more. The reaction can be conducted under 
atmospheric, superatmospheric or subatmospheric pressure with the use of a 
superatmospheric pressure normally being used on a commercial scale. 
One special advantage of the catalysts of the invention is their ability to 
withstand the feed of large amounts of olefin over the catalyst in a given 
time. This is normally measured in terms of WWH which is the weight of 
olefin per weight of catalyst per hour. In other words, these catalysts 
can efficiently work on large amounts of olefin.

SPECIFIC EMBODIMENTS 
Various catalysts of the invention were prepared as shown below. All 
catalysts contained 20% SiO.sub.2. 
EXAMPLE 1 
Sb.sub.0.5 K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12 O.sub.x 
A slurry of 63.56 g. (NH.sub.4).sub.6 Mo.sub.7 O.sub.24.4H.sub.2 O, 61.79 
g. of Nalco 34% silica sol and 2.19 g. Sb.sub.2 O.sub.3 was prepared and 
combined with a solution of 36.36 g. Fe(NO.sub.3).sub.3.9H.sub.2 O, 14.55 
g. Bi(NO.sub.3).sub.3.5H.sub.2 O, 39.29 g. Co(NO.sub.3).sub.2.6H.sub.2 O, 
21.80 g. Ni(NO.sub.3).sub.2.6H.sub.2 O and 3.03 g. of a 10% solution of 
KNO.sub.3. The mixture was evaporated, dried, heat treated at 290.degree. 
C. for three hours, 425.degree. C. for three hours and 550.degree. C. for 
16 hours. 
EXAMPLE 2 
SbK.sub.0.1 Cu.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12 O.sub.x 
This catalyst was prepared in essentially the same way as shown in Example 
1 but copper was added in the form of Cu(NO.sub.3).sub.2.3H.sub.2 O. 
EXAMPLES 3 AND 5 
Sb.sub.0.5 Cs.sub.0.5 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12 O.sub.x 
This catalyst was prepared in essentially the same manner as Example 1, 
except that CsNO.sub.3 replaced the potassium compound. 
EXAMPLES 4 AND 7 
Sb.sub.1.0 Cs.sub.0.5 S.sub.0.25 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12 
O.sub.x 
The catalyst was prepared in the same manner as described above except that 
Cs.sub.2 SO.sub.4 was employed to incorporate sulfur in the catalyst. 
EXAMPLE 6 
Sb.sub.0.5 Cs.sub.0.2 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12 O.sub.x 
The catalyst was prepared in the same manner as shown in Example 1, except 
that CsNO.sub.3 was employed rather than the potassium. 
In a fixed-bed reactor constructed of a 0.75 cm. inside diameter stainless 
steel tube was placed 5 cc. of each catalyst prepared above. The catalysts 
were tested at a temperature of 371.degree. C. using a feed of 
isobutylene/air/steam of 1/10/4 and an apparent contact time of 3.7.+-.0.4 
seconds. 
The results of these experiments are given in the Table. 
The results are stated as follows: 
##EQU1## 
In the Table MA is methacrolein and MAA is methacrylic acid. 
TABLE 
______________________________________ 
Oxidation of Isobutylene to Methacrolein 
and Methacrylic Acid Using a Catalyst of 
YNi.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12 O.sub.x 
Results, % 
Ex- Yield Per Pass Con- Select- 
ample 
Catalyst Y= 
MA MMA Total version 
ivity 
______________________________________ 
1 Sb.sub.0.5 K.sub.0.1 
60.8 4.9 65.7 100.0 65.7 
2 Sb.sub.0.5 K.sub.0.1 Cu.sub.0.1 
66.1 1.4 67.5 100.0 67.5 
3 Sb.sub.0.5 Cs.sub.0.5 
80.3 3.3 83.6 99.4 84.2 
4 Sb.sub.1.0 Cs.sub.0.5 S.sub.0.25 
74.1 1.0 75.1 82.1 91.4 
.sup. 5.sup.a. 
Sb.sub.0.5 Cs.sub.0.5 
61.1 8.5 69.6 98.8 70.5 
.sup. 6.sup.a. 
Sb.sub.0.5 Cs.sub.0.2 
66.1 5.3 71.4 100.0 71.4 
.sup. 7.sup.b. 
Sb.sub.1.0 Cs.sub.0.5 S.sub.0.25 
77.2 1.6 78.8 92.8 85.0 
______________________________________ 
.sup.a. pressure 12 p.s.i.g. 
.sup.b. pressure 9.7 p.s.i.g. 
EXAMPLE 8 
Preparation of acrolein and acrylic acid 
In the same manner as described in the examples above, a catalyst of 
Sb.sub.0.5 K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12 O.sub.x 
was prepared and used in the oxidation of propylene. The catalyst was 
placed in a 5 cc. reaction zone of a reactor constructed of a stainless 
steel tube. The temperature of the reaction zone was maintained at 
380.degree. C. and the apparent contact time was three seconds. A feed of 
propylene/air/steam of 1/11/4 was employed. Of the propylene fed, 96.8% 
was converted with a selectivity to acrolein and acrylic acid of 94.9%. 
The yield per pass of acrolein was 78.1%, the yield per pass of acrylic 
acid was 13.8% and the total yield per pass to acrolein and acrylic acid 
was 91.9%.