BE823897A - METHOD FOR MANUFACTURING METHACRYLIC ACID - Google Patents

Description

       

  "Method for manufacturing methacrylic acid"

  
The present invention relates to a process for the manufacture of methacrylic acid, characterized in that the catalytic vapor phase oxidation of methacrolein is carried out by passing it over a catalyst at the same time as air or a gas containing l molecular oxygen.

  
A large number of catalytic compositions for the manufacture of methacrylic acid by catalytic vapor phase oxidation of methacrolein have been proposed until this time.

  
day. For example, with regard to the catalytic system consisting essentially of P and Mo, the United States Patent

  
(1 ..

  
 <EMI ID = 1.1>

  
consisting of P, Mo and As or a composition of the same components in which Al has been incorporated, while in German Patent Application 2,258,547 a &#65533; catalytic composition consisting of P and Mo in which has been incorporated Tl and / or Rb and / or Cs and / or K, and in addition, Cr and / or Si and / or Al and / or Ti. On the other hand, with regard to the catalytic system consisting essentially of Mo and V, a composition of Mo-V fixed on silicon carbide is described in the German patent application
2,164,905 while a composition of Mo-V-Sb fixed on aluminum is described in the German patent application
2,038,763. On the other hand, in French Patent 2,040,546 a catalyst consisting of Mo-V-P is described.

  
However, when these proposed catalysts were tested under actual operating conditions, only low yields could be obtained. Moreover, since the method of their use cannot be considered efficient, these catalysts cannot be considered as fully satisfactory for commercial purposes. A particular drawback is that the quantity of by-products formed by the use of these catalysts is large. Simultaneous reactions such as polymerization or decomposition are also observed on the catalyst or on the internal walls of the reactor. Therefore, from the point of view of commercial operations, disadvantages such as reduced catalyst life and contamination of the reactor as well as increased pressure loss should be considered inevitable. .

  
The object of the present invention is to provide a commercially advantageous process for the manufacture of methacrylic acid by providing a new catalyst system which can overcome the drawbacks of conventional catalysts.

  
 <EMI ID = 2.1>

  
starting from methacrolein at a relatively low reaction temperature and further with high selectivity when using a catalytic oxide consisting of molybdenum, vanadium

  
 <EMI ID = 3.1>

  
from the group consisting of copper, cobalt, zirconium, bismuth, antimony and arsenic and / or at least one alkali metal (X), in specific proportions. In addition, it has been found that simultaneous reactions such as polymerization or decomposition on the catalyst or on the internal walls of the reactor during the reaction can be avoided.

  
Thus, according to this invention there is provided a process for the manufacture of methacrylic acid characterized in that the catalytic vapor phase oxidation of methacrylin is carried out with air or a gas containing molecular oxygen. &#65533; re in the presence of a catalytic oxide represented by the general formula

  

 <EMI ID = 4.1>


  
wherein Y is at least one metallic element selected from the group consisting of copper, cobalt, zirconium, bismuth, antimony and arsenic, X is at least one alkaline metallic element selected from the group consisting of sodium, potassium,

  
 <EMI ID = 5.1>

  
atomic ports of the different elements; and when d is 12,

  
 <EMI ID = 6.1>

  
this 0 - 3.0, c is 0.1 - 10, preferably 0.5 - 5.0, _e is 0.1 - 10, preferably 0.5 - 5.0, and f is a value which is determined by the valences and atomic ratios of the different elements, with the condition that the sum of a and b is greater than zero.

  
In this invention, the above catalytic oxide can be used as it is, but it is also possible to use it.
 <EMI ID = 7.1>
 attached to a carrier. As carrier material, any inert porous substance usually used may be mentioned:! sée or inert substances which can be granulated into a porous material. For example, substances such as alumina, silicon carbide, pumice stone, silica, zirconia, titanium oxides and magnesium silicate can be used.

  
 <EMI ID = 8.1>

  
be them.

  
Further, the catalyst of the process of the invention can not only be used in a fixed bed type reaction but also in a fluidized bed type reaction.

  
By way of example, a preferred procedure for the preparation of the catalyst of the invention will be described below. First, a complex is prepared by reacting vanadium pentoxide and orthophosphoric acid. Separately, to an aqueous solution of ammonium molybdate is added orthophosphoric acid and, if necessary, a nitrate of copper, cobalt, zirconium or bismuth, arse acid

  
 <EMI ID = 9.1>

  
by heating to obtain a solution to which is added the above complex, then, if necessary, an aqueous solution of an alkali metal hydroxide, sulfate or nitrate is added to obtain a solution combination, which solution is used as such or after being formed into a molded or fixed catalyst. In preparing the molded catalyst, a powdery carrier material is mixed with the above combined solution, after which the mixture is concentrated or evaporated to dryness and the concentrated or dried product is molded, then it is then calcined at a temperature. from 300 - 600 [deg.] C under air circulation, to thereby obtain a molded catalyst. On the other hand, if the above combined solution is deposited on a carrier material and calcined in the same way, a fixed catalyst is obtained.

   In addition, it is also possible to use aqueous solutions of vanadates such as vanadyl oxalate, vanadyl sulfate, etc., instead of the above complex in the preparation of the combined solution mentioned above. Further, the starting catalytic substance is not limited to the compounds mentioned above, and it is possible to use other compounds such as inorganic and organic acid salts and acid salts with a metal which can be decomposed by calcination.

  
According to a preferred application of the present invention, methacrylic acid is advantageously prepared by introducing a starting gas consisting of 1 - 10% by volume of methacrolein, 1 - 15% by volume of oxygen, 5 - 60% by volume of vapor, and the balance consisting of an inert gas such as nitrogen, carbon dioxide, carbon monoxide, etc., on the catalytic oxide mentioned above, at a temperature of
200 - 400 [deg.] C, preferably 230 - 350 [deg.] C and at a pressure ranging from normal atmospheric pressure to 10 atm, with a flow rate of

  
 <EMI ID = 10.1>

  
as a starting gas, a gas mainly containing methacrolein, obtained by the catalytic vapor phase oxidation of isobutylene or tertiary butanol.

  
The characteristics of the present invention resulting from the use of such a catalytic oxide are that, as already indicated, the formation of by-products is less, and therefore simultaneous reactions like polymerization on the catalyst or on the internal walls of the catalyst. reactor and decomposition are avoided, and the results obtained are very clearly superior to those obtained in the case of the previous practice in which the reaction rate of methacrolein is 60 - 90 mole% while the selectivity for l methacrylic acid is 70 - 90 mole%.

  
 <EMI ID = 11.1>

  
passage, as used here, are defined as follows:

  

 <EMI ID = 12.1>


  
The following non-limiting examples are given in order to more specifically illustrate the invention.

Example 1

  
106 grams of ammonium molybdate was dissolved in
400 ml of water. Separately, 5.8 grams of 85% orthophosphoric acid was diluted with 30 ml of water and then 3.6 grams of copper nitrate was dissolved therein. This latter aqueous solution

  
was added to the above aqueous ammonium molybdate solution, after which the combined solution was aged in

  
heating it with vigorous stirring. Further, separately, 5.8 grams of 85% orthophosphoric acid was diluted in 30 ml of water, then 4.6 grams of vanadium pentoxide was then added thereto, followed by heating with stirring, water. was evaporated from the mixture to obtain a yellow complex. This complex was then added to the precipitate of phosphorus, molybdenum and copper from the above reaction, after which a solution of 2.8 grams of potassium hydroxide in 30 ml of water was added and then carried out. concentration to dryness. The resulting solid was then dried for a further 4 hours at 200 [deg.] C, crushed into particles about 5 mm in size and then calcined for 5 hours at 400 [deg.] C with circu-

  
(h lation of air. The composition of the catalyst thus obtained, expressed as the atomic ratio of its metallic elements, except

  
 <EMI ID = 13.1>

  
Fifty ce. of this catalyst were placed in a U-shaped stainless steel reactor having an internal diameter of 25 mm, and then the packed reactor was immersed in a bath of molten salt of 280 [deg.] C (NT 280 [ deg.] C). A ga- mixture! Zeux composed of 4% by volume of methacrolein, 10% by volume of oxygen, 44% by volume of nitrogen and 40% by volume of vapor was introduced into the reactor and, while
-1 <EMI ID = 14.1>

  
Dation of methacrolein was performed. The results obtained are shown in Table 1.

Example 2

  
The oxidation reaction was carried out under conditions identical to those of Example 1, using the same catalyst as that obtained in this example but in NT.

  
 <EMI ID = 15.1>

  
 <EMI ID = 16.1>

  
The catalyst was prepared under identical conditions.

  
 <EMI ID = 17.1>

  
 <EMI ID = 18.1>

  
cobalt trate (Example 3), 3.8 grams of arsenious acid

  
 <EMI ID = 19.1>

  
ple 5). The catalyst thus obtained was used to carry out the oxidation reaction of methacrolein. The results obtained are shown in Table 1.

Example 6

  
The same catalyst as that obtained in Example 1 was used, and a gas mixture consisting of 5 mole% methacrolein, 10 mole% oxygen, 45 mole% nitrogen and 40 moles.

  
 <EMI ID = 20.1> <EMI ID = 21.1>

  
in Table 1.

Example 7

  
The same catalyst as that obtained in Example 4a and used and the oxidation reaction of methacrolein was carried out by introducing a gas mixture consisting of 5 mole% methacrolein, 10 mole% oxygen, 45 mole% d nitrogen and 40 mole% of vapor under the conditions indicated in Table 1. in which are also indicated the results obtained.

  
Examples 8 - 9

  
The preparation of the catalyst was carried out under the same conditions as in Example 1, but using, instead of 3.6 grams of copper nitrate, 12.0 grams of bismuth nitrate (Example 8), or 8 , 9 grams of zirconium sulfate (Example 9). The catalyst thus obtained was used and the methacrolein oxidation reaction was then carried out by operating as in Example 1. The results obtained are shown in Table 1.

  
Examples 10 - 12

  
A catalyst having the composition shown in Table 1 was prepared following the same procedure as that described in Example 1, but using, instead of 2.8 grams of potassium hydroxide, 4.2 grams of potassium hydroxide. sodium nitrate (Example 10) 6.7 grams of rubidium sulfate
(Example 11) or 9.7 grams of cesium nitrate (Example 12). The catalyst thus obtained was then used to carry out the methacrolein oxidation reaction as in Example

  
1. The results obtained are shown in Table 1.

Example 13

  
A catalyst having the composition indicated in <EMI ID = 22.1>

  
tion of potassium nitrate. This catalyst was used and the methacrolein oxidation reaction was carried out under conditions identical to those of Example 1. The results obtained are shown in Table 1.

Example 14

  
A catalyst having the composition shown in Table 1 was prepared by operating as in Example 1, except that in the step of preparing the complex of orthophosphoric acid and vanadium pentoxide, 2.9 grams of orthophosphoric acid at 85% and 4.6 grams of vanadium pentoxide was used. The catalyst thus obtained was employed and the methacrolein oxidation reaction was carried out under conditions identical to those of Example 1. The results obtained are shown in Table 1.

Example 15

  
A catalyst was prepared by operating as in Example 1, except that in the step of preparing the complex of orthophosphoric acid and vanadium pentoxide, it was used
11.6 grams of 85% orthophosphoric acid and 4.6 grams of vanadium pentoxide. The catalyst thus obtained was then used and the methacrolein oxidation reaction was carried out under conditions identical to those of Example 1. The results obtained are shown in Table 1.

Example 16

  
106 grams of ammonium molybdate was dissolved in
400 ml of water. Separately, 11.6 grams of 85% orthophosphoric acid was diluted in 30 ml of water, in which then 3.6 grams of copper nitrate was dissolved. This latter aqueous solution was added to the above aqueous ammonium molybdate solution, after which the combined solution was aged by heating it with vigorous stirring. In addition, separately 11.6 grams of 85% orthophosphoric acid was diluted in 30 ml of water, to which was then added 6.9 grams of vanadium pentoxide, and then the water was evaporated from the mixture. heating with stirring to obtain a yellow complex. This complex was then added to the precipitate

  
 <EMI ID = 23.1>

  
above, after which a solution of 2.8 grams of potassium hydroxide in 30 ml of water was finally added. Then, the experiment was carried out as in Example 1 to obtain a catalyst having the composition shown in Table 1. The catalyst thus obtained was then used and the reaction! The oxidation process of methacrolein was carried out under conditions identical to those of Example 1. The results obtained are shown in Table 1.

Example 17

  
A catalyst having the composition shown in Table 1 was prepared by operating as in Example 1, except that in the step of preparing the complex of orthophosphoric acid and vanadium pentoxide, 5.8 grams were used. 85% orthophosphoric acid and 9.2 grams of pentoxide

  
vanadium. The catalyst thus obtained was then used and the methacrolein oxidation reaction was carried out under conditions identical to those of Example 1. The results obtained are shown in Table 1.

Example 18

  
A catalyst having the composition shown in Table 1 was prepared by operating as in Example 1, except that in the step of preparing the complex of orthophosphoric acid and vanadium pentoxide, 5.8 grams of sodium were used. 85% orthophosphoric acid and 13.8 grams of vanadium pentoxide. Using the catalyst thus obtained, we have

  
 <EMI ID = 24.1> <EMI ID = 25.1>

  
Figures are shown in Table 1.

  
Examples 19 - 20

  
A catalyst was prepared by operating as in Example 3, but varying the amount of cobalt nitrate used (14.6 grams (Example 19) or 29.2 grams (Example

  
20)) in order to obtain a catalyst having the composition shown in Table 1. The catalyst thus obtained was used and the oxidation reaction of methacrolein was carried out under the same conditions as in 1. Example 1. The results obtained are shown in Table 1.

  
Examples 21 - 22

  
A catalyst having the composition shown in Table 1 was prepared by operating as in Example 3, but varying the amount of potassium hydroxide used:
in the preparation of the catalyst (4.2 grams (Example 21) or 5.6 grams (Example 22)). The catalyst thus obtained was then used and the methacrolein oxidation reaction was carried out under conditions identical to those of Example 1. The results obtained are shown in Table 1.

Example 23 '

  
106 grams of ammonium molybdate was dissolved in
400 ml of water. Separately, 5.8 grams of 85% orthophosphoric acid was diluted in 30 ml of water, in which then 3.6 grams of copper nitrate was dissolved. The latter solution was added to the above aqueous ammonium molybdate solution, after which, the combined solution was aged by heating it with vigorous stirring. Further, separately, 2.9 grams of 85% orthophosphoric acid was diluted in 30 ml of water, and then 4.6 grams of vanadium pentoxide was added thereto, and then the water was evaporated off.

  
of the mixture by heating with stirring to obtain a complex <EMI ID = 26.1>

  
nel of phosphorus, molybdenum and copper above, then another 14.5 grams of antimony trioxide as such was added and finally a solution of 2.8 grams of potassium hydroxide in 30 ml of water, after which the mixture was concentrated to dryness. Then, the experiment was carried out as in Example 1 to obtain a catalyst having the composition shown in Table 1. This catalyst was used and the methacrolein oxidation reaction was carried out as in Example 1. The results obtained are shown in Table 1.

Example 24

  
A catalyst was prepared under the same conditions as in Example 23, but using 29.0 grams of antimony trioxide. The catalyst thus obtained was used and the methacrolein oxidation reaction was carried out by operating as in Example 1. The results obtained are shown in Table 1.

Example 25

  
A catalyst was prepared by operating as in Example 24 but using, instead of the aqueous solution of potassium hydroxide, a solution of 2.8 grams of potassium hydroxide and 4.9 grams of potassium nitrate. cesium in 30 ml of water. This catalyst was used and methacrolein was oxidized as in Example 1. The results obtained are shown in Table 1.

Example 26

  
A catalyst was prepared by operating as in Example 23 but using 1.9 grams of cobalt oxide instead of antimony trioxide. The catalyst thus obtained was used and the methacrolein was oxidized as in Example 1.

  
 <EMI ID = 27.1>

  

 <EMI ID = 28.1>


  

 <EMI ID = 29.1>
 

  

 <EMI ID = 30.1>
 

Example 27

  
106 grams of ammonium molybdate was dissolved in
200 ml of water and to this solution was then added 5.8 grams of 85% orthophosphoric acid, after which the mixture was well stirred with heating until a white precipitate formed. . Separately, 4.6 grams of vanadium pentoxide was added to a solution of 8.8 grams of oxalic acid in 100 ml of water with heating and stirring well until a homogeneous dark blue solution was obtained. This oxalic acid solution was then added to the solution containing the above precipitate, obtained from ammonium molybdate and orthophosphoric acid, after which, a solution of 2.8 grams of potassium hydroxide in 30 ml of water was added and the combined solution was condensed to dryness.

   The resulting solid was dried for 4 hours at 200 [deg.] C then it was crushed and molded into cylindrical tablets 5 mm in diameter x 5 mm in length. The tablets were calcined for 4 hours at 400 [deg.] C. The composition of the catalyst thus obtained, expressed in atomic ratios

  
 <EMI ID = 31.1>

  
ml of this catalyst was placed in a U-shaped stainless steel reactor and the type was immersed in molten salt heated to 280 [deg.] C. (NT 280 [deg.] C). Then, a gas mixture consisting of 4% by volume of methacrolein, 10% by volume of oxygen, 46% by volume of nitrogen and 40% by volume of vapor was introduced into the reactor, and the reaction was carried out while

  
 <EMI ID = 32.1>

  
The states obtained are shown in Table 2. As products, in addition to methacrylic acid, the formation of acetic acid, carbon dioxide and carbon monoxide was noted.

Example 28

  
 <EMI ID = 33.1> <EMI ID = 34.1>

  
 <EMI ID = 35.1>

  
 <EMI ID = 36.1>

  
A catalyst shown in Table 2 was prepared

  
 <EMI ID = 37.1>

  
if prepared was used and the reaction was carried out as

  
 <EMI ID = 38.1>

  
The results obtained are shown in Table 2. However, there were the following exceptions. Instead of 2.8 grams of potassium hydroxide as used in Example 27, in

  
 <EMI ID = 39.1>

  
of sodium, 6.7 grams of rubidium sulfate and 9.8 grams of cesium nitrate, respectively.

  

 <EMI ID = 40.1>


  

 <EMI ID = 41.1>
 

  
 <EMI ID = 42.1>

  
106 grams of ammonium molybdate was dissolved in
400 ml of water. Separately, 9.8 grams of oxalic acid was dissolved in 100 ml of water, after which 4.6 grams of vanadium pentoxide was added with heating and then the mixture was well stirred until a solution was obtained. homogeneous deep blue. This latter solution was then added to the above aqueous ammonium molybdate solution, after which the resulting combined solution was evaporated to dryness with stirring. The resulting solid was then dried for 4 hours at 200 [deg.] C, crushed into particles having a size.

  
 <EMI ID = 43.1>

  
under air circulation. The composition of the catalyst thus obtained, expressed in atomic ratios excluding the oxy-

  
 <EMI ID = 44.1>

  
of methacrolein. The results obtained are shown in Table 3.

  
Witness 2

  
A catalyst having a composition shown in Table 3 was prepared by operating as in Example 1 but without adding copper nitrate and potassium hydroxide in the preparation of the catalyst. This catalyst was used for the oxidation of methacrolein and the results obtained are shown in Table 3.

  
Witness 3

  
A catalyst having the composition shown in Table 3 was prepared by operating exactly as in Example 27 but without using vanadium pentoxide and oxalic acid. This catalyst was used for the oxidation of methacrolein and the results obtained are shown in Table 3.

  
 <EMI ID = 45.1>

  
A catalyst having the composition shown in Table 3 was prepared by operating exactly as in Example 27 but without using orthophosphoric acid. This catalyst was used for the oxidation of methacrolein and the results obtained are shown in Table 3.

  
Witness 5

  
22.2 grams of ammonium metavanadate and 106 grams of ammonium molybdate were dissolved in 400 ml of water. After

  
 <EMI ID = 46.1>

  
resulting, this was evaporated to dryness, with stirring. After drying the resulting solid for a further 4 hours at 200 [deg.] C, it was ground into particles having a size of about 5 mm and then calcined for 5 hours at
400 [deg.] C under circulating air to obtain a catalyst having the composition shown in Table 3. This catalyst was used and the methacrolein oxidation reaction was carried out. The results obtained are shown in Table
3.

  
Witness 6

  
106 grams of ammonium molybdate was dissolved in
400 ml of hot water, after which 11.6 grams of 85% orthophosphoric acid were mixed therein and then 14.6 grams of antimony trioxide were also added thereto. This mixture was then evaporated to dryness with stirring. The resulting solid was dried for a further 4 hours at 200 [deg.] C and then it was ground into particles having a size of about 5 mm and then calcined for 5 hours at 400 [deg.] C under a air circulation to obtain a catalyst having the composition shown in Table 3. This catalyst was used in the oxidation of methacrolein. The results obtained are indicated in the

  
 <EMI ID = 47.1> .........

  
 <EMI ID = 48.1>

  
In the preparation of the catalyst as in Control 5, 530 grams of an aluminum sponge having a size of 6-10 mesh, produced by Mitsuwa Chemical Co. Ltd., Japan, was added as a carrier material after the addition of the antimony trioxide, after which the mixture was evaporated to dryness. Then the experiment was carried out as in Control 5 to prepare the catalyst which was used in the oxidation of methacrolein. The results obtained are shown in Table 3.

  

 <EMI ID = 49.1>


  

 <EMI ID = 50.1>
 

  
 <EMI ID = 51.1>

CLAIMS

  
 <EMI ID = 52.1>

  
ized in that the catalytic vapor phase oxidation of methacrolein is carried out with a member selected from the group consisting of air and gas containing molecular oxygen in the presence of a catalytic oxide of general formula

  

 <EMI ID = 53.1>


  
wherein Y is at least one metallic element selected from "the group consisting of copper, cobalt, zirconium, bismuth, antimony and arsenic, X is at least one alkaline metallic element selected from the group consisting of sodium, potassium,

  
 <EMI ID = 54.1>

  
atomic ratios of the different elements; and when d is 12,

  
 <EMI ID = 55.1>

  
f is a value which is determined by the valences and the atomic ratios of the various elements, with the condition that the sum of a and b is greater than zero.


    

Claims (1)

2.- Method according to claim 1, characterized in that <EMI ID = 56.1> ! steam at a temperature of 200 - 400 [deg.] C, at a pressure between normal atmospheric pressure and 10 atmospheres <EMI ID = 57.1> 3.- A process for the manufacture of methacrylic acid characterized in that the catalytic vapor phase oxidation of methacrolein is carried out with a member selected from the group consisting of air and gas containing molecular oxygen at a temperature of 230 - 350 [deg.] C, a pressure between normal atmospheric pressure and 10 atmospheres and with a flow rate of 500 - 3000 h, in the presence of a catalytic oxide general formula <EMI ID = 58.1> wherein Y is at least one metallic 1 <1> bond * selected from the group consisting of copper, cobalt, zirconium, bismuth, antimony and arsenic, X is at least one alkaline metallic element selected from the group consisting of sodium, potassium, ; <EMI ID = 59.1> atomic ratios of the different elements; and when d is 12, <EMI ID = 60.1> and f is a value which is determined by the valences and atomic ratios of the different elements, with the proviso that the sum of a and b is greater than zero. 4.- Catalytic oxide composition characterized in that it is represented by the general formula '. <EMI ID = 61.1> wherein Y is at least one metallic element selected from the group consisting of copper, cobalt, zirconium, bismuth, antimony and arsenic, X is at least one alkaline metallic element selected from the group consisting of sodium, potassium, <EMI ID = 62.1> atomic ratios of the different elements; and when d is 12, <EMI ID = 63.1> and f is a value which is determined by the valences and atomic ratios of the different elements, with the proviso that the sum of a and b is greater than zero. 5.- Catalytic oxide composition characterized in that it is represented by the general formula <EMI ID = 64.1> wherein Y is at least one metallic element selected from the group consisting of copper, cobalt, zirconium, bismuth, antimony and arsenic, X is at least one alkaline metallic element selected from the group consisting of sodium, potassium, <EMI ID = 65.1> \ <EMI ID = 66.1> <EMI ID = 67.1> atomic ratio of the different elements, with the condition <EMI ID = 68.1> .