JPH0316929B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a conjugated diolefin by an oxidative dehydrogenation method, and more specifically,
The present invention relates to a method for efficiently producing a target product by using a novel catalyst in producing a conjugated diolefin corresponding to the monoolefin by oxidizing and dehydrogenating the monoolefin having the above in the gas phase with molecular oxygen. A monoolefin having 4 or more carbon atoms, such as normal butene or isopentene, is oxidized and dehydrogenated in the gas phase with molecular oxygen in the presence of a catalyst to form a conjugated diolefin (i.e., 1,3- Methods for producing (butadiene, isoprene) are known. Specific examples of such known techniques include, for example, multicomponent catalysts containing molybdenum, bismuth and iron as essential components (for example, Japanese Patent Publications No. 49-3498, No. 49-5321, No. 49-5321,
52-39006, JP-A-50-64202, etc.), and multi-component catalysts containing molybdenum, bismuth and chromium as essential components (e.g., JP-A-50-64191, etc.). When using this catalyst system, there is a large difference in reactivity between the isomers of monoolefin, which is the raw material. Therefore, when this catalyst system is applied to a mixture of isomers of monoolefin, which is available as an industrially inexpensive raw material, The drawback was that the yield of the desired conjugated diolefin was significantly reduced. Therefore, the inventors of the present invention have long focused on developing a catalyst that does not cause any difference in reactivity depending on the isomer of the raw material monoolefin. It was discovered that some of the catalysts in the system are effective (for example, Japanese Patent Application Laid-open No. 140931/1983,
56-150023, etc.). However, as a result of further investigation, we found that while using these catalysts had the above advantages, the reaction temperature was a little higher, making the reactor material more expensive, and it was difficult to continue the reaction for a long time. As a result, new problems were discovered, such as the tendency for the reaction system to clog due to by-products of high-boiling substances. Therefore, the inventor of the present invention has found that there is almost no difference in reactivity depending on the isomer of the raw monoolefin at a lower reaction temperature, and that it is possible to efficiently obtain a conjugated diolefin with a high boiling point even when used for a long time. As a result of intensive studies aimed at developing a catalyst that does not produce by-products, the inventors discovered that it is effective to add aluminum and iron as essential components, leading to the completion of the present invention. Thus, according to the present invention, when a monoolefin having 4 or more carbon atoms is oxidized and dehydrogenated in the gas phase with molecular oxygen to produce a conjugated diolefin corresponding to the monoolefin, the general compositional formula Mo _a Bi _b Cr _{c Ni d Al e Fe f} , Ti, Nb, Ta,
Represents one or more elements selected from Co, La, Ce, Nd and Mn, a, b, c, d, e, f, g,
h and i are respectively Mo, Bi, Cr, Ni, Al, Fe,
The number of atoms of X, Y and O, when a = 12, b = 0.05 to 20, preferably 0.1 to 8, c = 0.05
~20, preferably 0.1~10, d=0.1~30, preferably 1~20, e=0.01~20, preferably 0.05~
10, f=0.01-20, preferably 0.05-10, g=
0.001-20, preferably 0.01-10, h=0-20,
It preferably takes a value of 0.01 to 10, where i is the number of oxygen atoms satisfying the valences of other elements. ) A method for producing a conjugated diolefin is provided, which is characterized by using a catalyst represented by: The monoolefin used as a reaction raw material in the present invention may be any monoolefin having 4 or more carbon atoms, which has been conventionally used as a raw material for synthesizing conjugated diolefin by oxidative dehydrogenation reaction. As an example, butene-1,
Butene-2, Pentene-1, Pentene-2, 2-
Methylbutene-1,2-Methylbutene-2,3-
Methylbutene-1,2,3-dimethylbutene-
Examples include 1,2,3-dimethylbutene-2. These monoolefins do not necessarily need to be used in an isolated form, but can be used in any mixture form as required. For example, when trying to obtain 1,3-butadiene, high-purity butene-1 or butene-2 can be used as a raw material, but 1,3-butadiene can be obtained from the _C4 fraction, which is a by-product of naphtha cracking.
A fraction containing butene-1 and butene-2 as main components obtained by separating butadiene and isobutylene (hereinafter referred to as BBRR) and a butene fraction produced by dehydrogenation or oxidative dehydrogenation of normal butane are used. Even in that case, a yield equivalent to that obtained when using a single highly purified raw material can be obtained. In addition, when trying to obtain isoprene or 1,3-pentadiene, it is possible to similarly use a distillate containing isopentene as the main component or a distillate containing normal pentene as the main component, and furthermore, a distillate containing isopentene and normal pentene as the main component. Isoprene and 1,3-pentadiene can also be synthesized simultaneously by using the _G5 monoolefin fraction as a raw material. In the present invention, a catalyst represented by the general compositional formula described above is used. The major structural feature of this catalyst system is the well-known Mo
- Aluminum is selected from the Y components of the Bi-Cr-Ni-X-Y catalyst, and iron, which was considered to be an ingredient to be excluded in the above publication, is combined to make chromium, nickel, aluminum, and iron essential ingredients. If even one of these four essential elements, chromium, nickel, or aluminum, is missing, the difference in reactivity between monoolefin isomers cannot be eliminated, and the I can't control my life either. In addition, in the absence of iron, although there is almost no difference in reactivity between monoolefin isomers, the reaction temperature at which the same catalytic performance (diolefin yield) is obtained becomes higher, and high-boiling products as by-products are also produced. There will be more. Furthermore, the X component is also an essential component of the present catalyst, and in the absence of the X component, the reaction becomes unstable and the reactivity decreases. On the other hand, although the Y component is not necessarily required, the presence of this component can further reduce the production of high-boiling by-products. Each element constituting the X component and Y component has the same effect, but among them, K, Rb, Cs,
Tl, Ba, Zn, Cd and P, In and Nd as Y components
When Mn and Mn are used, a catalyst exhibiting particularly excellent performance can be obtained. Further, each element constituting the X component and the Y component does not necessarily need to be used alone, and two or more types can be used in combination as necessary. The catalyst used in the present invention can be prepared by various methods known in the art, such as evaporation to dryness, oxide mixing, coprecipitation, and the like. As the raw materials for each element used in the preparation of the catalyst, any material can be used as long as it forms the catalyst of the present invention by calcination. Examples of these include salts such as ammonium salts, nitrates, carbonates, organic acid salts, and halides of each element, free acids,
acid anhydride, condensed acid, or phosphomolybdic acid,
Examples include heteropolyacids containing molybdenum such as silicomolybdic acid, and heteropolyacid salts thereof such as ammonium salts and metal salts. The calcination treatment carried out for the purpose of converting the catalyst raw material into the catalyst of the present invention or activating the catalyst is usually performed at a temperature of about 300 to 900°C, preferably 450 to 700°C, under the flow of a gas containing molecular oxygen. It lasts from 4 hours to 16 hours.
Further, if necessary, a primary firing treatment may be performed at a temperature equal to or lower than this firing temperature, and then a firing treatment may be performed at the above temperature. To show an example of the method for preparing the catalyst of the present invention, an element of component X is added to an aqueous solution of ammonium molybdate,
After adding an aqueous solution in which salts of the elements of chromium, nickel, bismuth, aluminum, iron, and Y component are dissolved, the pH is adjusted to a range of 2 to 9 using an ammonia aqueous solution or a nitric acid aqueous solution, and the mixture is stirred. The resulting slurry suspension is dried with a suitable carrier material added if necessary, and the resulting cake-like material is dried in air and then calcined at the above-mentioned calcination temperature. The catalyst of the present invention can be used as it is, but it can also be used by attaching it to a carrier of an appropriate shape, or diluting it with a carrier (diluent) in the form of powder, sol, or gel. .
As the carrier or diluent, known carriers or diluents may be used, such as titanium dioxide, silica gel, silica sol, diatomaceous earth, silicon carbide, inert alumina, pumice, silica-alumina, bentonite, zeolite, talc, and refractories. A carrier containing is preferred. At this time, the amount of carrier can be appropriately selected. The catalyst can be in a suitable form as powder or tablets and can be used in any fixed bed, moving bed or fluidized bed method. The reaction between monoolefin and molecular oxygen in the present invention is carried out according to a conventional method except for using the above-mentioned novel catalyst. For example, the source of molecular oxygen does not necessarily have to be highly purified oxygen; rather, air is industrially practical. If necessary, an inert gas that does not adversely affect the reaction (e.g. water vapor, nitrogen, argon, carbon dioxide,
It can be diluted with waste gas (e.g., after removing useful hydrocarbons from the reaction product). Furthermore, the reaction temperature is 250-700℃, preferably 300-600℃
℃, reaction pressure is normal pressure ~ 10 atm, space velocity (SV) of total feed gas is 200 ~ 10000hr ^-1 , preferably 300
~6000hr ^-1 (NTP standard), monoolefin concentration in the feed gas is 0.1-40% by volume, monoolefin to oxygen ratio is 1:0.1-7, preferred feed gas composition is monoolefin:air:steam=1: 2～
30:0 to 50 (molar ratio). According to the present invention, 1,3-butadiene, 1,3-butadiene, and 1,3-butadiene can be obtained from monoolefins, such as conjugated diolefins, such as normal butene, isopentene, normal pentene, and 2,3-dimethylbutene, respectively.
Isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, etc. can be synthesized. In particular, in the catalyst system used in the present invention, there is almost no difference in reactivity between the monoolefin isomers, and there is no decrease in activity due to paraffins. This method is suitable when the raw material is a distillate that is industrially available at low cost, such as a mixture of the Conjugated diolefins can be obtained at In addition, the catalyst system used in the present invention has a long catalyst life,
There is little by-product of high-boiling substances that can clog the reactor outlet tube, and even if the catalyst strength is increased, the catalyst activity is not adversely affected, so it is possible to carry out stable reactions over a long period of time. It has the advantage that even if the monoolefin concentration is increased and the space velocity is increased, there is little decrease in yield. The present invention will be explained in more detail with reference to Examples below. In addition, the reaction rate, selectivity, and single flow yield in Examples were calculated according to the following formula. At that time, if a corresponding conjugated diolefin was present in the monoolefin used as a raw material, that amount was removed from the amount of conjugated diolefin produced, and the partially isomerized monoolefin was treated as an unreacted monoolefin. . Furthermore, the representation of oxygen in the catalyst components has been omitted for the sake of brevity. Monoolefin reaction rate (%) = Reacted monoolefin (mol) / Supplied monoolefin (mol) x 100 Diolefin single stream yield (%) = Corresponding conjugated diolefin produced (mol) / Supplied monoolefin (mol) )×100 Diophine selectivity (%) = corresponding conjugated diolefin produced (mol)/monoolefin reacted (mol)
×100 In addition, by-product high-boiling substances were measured as follows. That is, a copper tube with an inner diameter of 8 mm and a length of 3 m is attached to the outlet of the reaction tube, kept at 95° C. in a hot water bath, a reaction gas is passed through it for 100 hours, and then dried under reduced pressure at room temperature until there is no weight change. The weight of the copper tube measured in advance was subtracted from this weight to determine the amount of by-product high boiling point substances. Example 1 Bismuth nitrate 48.5g, aluminum nitrate 37.5g
g, ferric nitrate 4.04g, nickel nitrate 232.6g,
150g of chromium nitrate and 2.02g of potassium nitrate
Solution A was obtained by adding the solution to 400 ml of warm water and dissolving it in 400 ml of warm water. After sufficiently heating and stirring Solution A, Add Solution B and stir vigorously. After adding 3% by weight aqueous ammonia to adjust the pH to 5, the mixture was allowed to stand at room temperature for 50 hours and evaporated to dryness on an oil bath. After drying this at 120°C for 8 hours, it was primarily fired at 350°C for 4 hours in an air stream, and the obtained primary fired product was pulverized into 100 meshes or less.
Next, 40% by weight of silicon carbide powder (1500 mesh or less) and 3% by weight of silica (20% by weight of silica sol) were added to the pulverized primary fired product, and lubricants (ethylene glycol and methyl cellulose) were added to the pulverized primary fired product. After adding an appropriate amount of warm water solution), knead with a grinder until it is sufficiently homogeneous.
This was extruded to a diameter of 3 mm and a length of 1 cm.
Dry at 120°C for 16 hours. This was heated to 400℃ for 2 hours under air circulation, and then heated to 570℃.
It was baked for 6 hours. The composition of the elements (the same applies hereinafter) excluding oxygen and the carrier of the obtained catalyst is shown as Mo ₁₂ Bi ₁ Cr ₃ Ni ₈ Al ₁ Fe _0.1 K _0.2 [Catalyst No. (1)]. 100 ml of the catalyst obtained in this way has an inner diameter of 2.5 cm and a length of
Fill a 60cm stainless steel reaction tube and heat to 310℃ in a metal bath.
℃, and using each of the normal butenes having the composition shown in Table 1, the flow rate of normal butene contained in these is 18 per hour (gaseous, NTP standard) and the flow rate of air is 132 per hour (NTP standard). It was passed through the catalyst layer in such a manner that The results obtained 5 hours after the start of the reaction are shown in Table 2 (the same applies below). The results in Table 2 show that when the catalyst of the present invention is used, there is almost no difference in the reactivity of butene-1 and butene-2, and both give 1,3-butadiene in high yield. Furthermore, it is a very unique phenomenon that even when using BBRR, which is industrially available at low cost and in large quantities, as a raw material, the yield is comparable to that when using high-purity butene. Furthermore, the production of by-products with high boiling points was small, and during the collection period of these high-boiling points, no troubles due to clogging of the pipes were observed when any of the raw materials were used.

【table】

[Table] Example 2 Catalysts shown in Table 3 [No. (2) to No. (19 )] was prepared.
As the catalyst raw material for element X, 85% phosphoric acid was used for phosphorus, and nitrates were used for other elements. For each catalyst thus prepared,
As shown in Table 1 in a similar manner to Example 1
The reaction was carried out using BBRR-1, and the obtained results are shown in Table 3.

【table】

【displayed. Comparative Example 1 Regarding catalyst No. (1) used in Example 1, Cr, Ni,
Comparative catalysts Nos. (c-1) to (c-7) were prepared in exactly the same manner except that Al or Fe was deleted as appropriate. For each of the catalysts thus prepared, reactions were carried out in the same manner as in Example 1 using butene-1, trans-butene-2 and BBRR-1 shown in Table 1. The results obtained are shown in Table 4.

[Table] From this result, Cr, Ni, and
It can be seen that if even one of Al and Fe is missing, the catalytic performance is significantly reduced, and at the same time, a large amount of high boiling point substances are produced as by-products. Also, comparative catalyst No. (c-
In all comparative catalysts except 4), the reactivity of butene-2 is significantly inferior to that of butene-1, and it can be obtained industrially in large quantities and at low cost.
When BBRR is used as a raw material, a satisfactory butadiene yield cannot be obtained. Comparative catalyst No. (c-4) was prepared using a metal bath in the reactor as described in JP-A-56-140931.
When the temperature is 350°C, excellent performance is shown, but when the metal bath in the reactor is set at 310°C as in this comparative example, the catalyst performance is significantly reduced. In addition, in the reaction using the comparative catalyst, the copper pipe for collection was blocked three or more times during the collection of high-boiling by-products.
Each time I had to pause my reaction. Example 3 A catalyst having the composition Mo ₁₂ Bi ₁ Cr ₃ Ni ₈ Al ₁ Fe _0.1 K _0.2 Yh was prepared in the same manner as in Example 1 except that the Y component was added. Y component catalyst raw material Nb and
For Ta, use a fine powder oxide, suspend it in warm water and add it to Solution A, for Ti, add a chloride aqueous solution to Solution A, and for other Y components, add a nitrate aqueous solution to Solution A. added to. Example 1 for each catalyst thus prepared
The reaction was carried out using BBRR-1 in the same manner as described above. The results obtained are shown in Table 5.

[Table] Example 4 100 ml of the catalyst obtained in Example 1 was filled into a stainless steel reaction tube with an inner diameter of 2.5 cm and a length of 60 cm, and the mixture was heated in a metal bath.
Heating to 320℃ and using BBRR-1
When a supply gas of 1: air: water vapor = 15:53:32 (molar ratio) was passed for a contact time of 2 seconds (NTP standard), the reaction rate of normal butene contained in BBRR-1 was 94.1%, 1, 3-butadiene yield 85.2%,
The 1,3-butadiene selectivity was 90.5%. Further, the high boiling point rate of the by-product collected in the same manner as in Example 1 was 0.66 g. Example 5 A reaction was carried out in the same manner as in Example 4, except that a waste gas obtained by removing hydrocarbons from the reaction product gas was used instead of water vapor as the feed gas. In this case, the waste gas contained unreacted oxygen and byproducts carbon monoxide and carbon dioxide in addition to nitrogen, but the reaction rate of normal butene was 94.4%.
The 1,3-butadiene yield was 85.6%, and the 1,3-butadiene selectivity was 90.7%. Further, the amount of high-boiling by-products collected in the same manner as in Example 1 was 1.23 g. Example 6 The reaction was started in the same manner as experiment number (1-5) in Example 1, and after 100 hours had passed, the reaction was continued to test the life of the catalyst. the result,
After 2000 hours, the reaction rate of normal butene in BBRR-1 was 93.8%, and the yield of 1,3-butadiene was
The selectivity for 1,3-butadiene was 86.0% and 91.7%, which was substantially the same as the activity at the beginning of the reaction. Furthermore, the amount of high-boiling by-products was 0.87 g, which had decreased since the beginning of the reaction. During this period, we supplied
Although the components and composition of BBRR-1 varied each time the raw materials were replaced, the reaction was always stable and the reaction results were essentially constant. Comparative Example 2 Comparative catalyst No. (c-1) and No. used in Comparative Example 1
The reactions using BBRR-1 according to No. (c-3) and No. (c-4) were continued as they were, and continuous operation was performed for a long time in parallel with Example 6. As a result, the inner diameter of the reactor outlet due to by-product high-boiling substances in both catalysts was 8.
Due to frequent blockages in the piping, which is made of copper pipes with a diameter of 1.5 mm, operation had to be shut down after 500 hours. Example 7 In Example 1, normal pentenes (pentene-1 and pentene-2) and isopentene (3-methyl-
Using a hydrocarbon mixture containing 1-butene-1, 2-methyl-butene-1 and 2-methyl-butene-2), the combined flow rate of orthopentene and isopentene contained therein was 18 (gaseous, NTP
The reaction was carried out using the same catalyst and the same method as in Example 1, except that a feed gas with an air flow rate of 132/hour (NTP standard) was used. As a result, the reaction rate of isopentene was 76.4%, the isoprene yield was 66.2%, and the isoprene selectivity was 86.6%, and the reaction rate of normal pentene was 79.7%, 1,3-
The pentadiene yield was 69.5%, and the 1,3-pentadiene selectivity was 87.2%. The amount of high-boiling by-products measured in the same manner as in Example 1 was 0.92 g.

[Table] Comparative Example 3 Example 7 except that comparative catalyst No. (c-3) was used
When the reaction was carried out in the same manner as above, the reaction rate of isopentene was 46.3%, the isoprene yield was 30.3%, and the isoprene selectivity was 65.4%.The reaction rate of normal pentene was 47.1%, and the yield of 1,3-pentadiene was 65.4%. The rate is
The selectivity for 1,3-pentadiene was 31.8% and 67.5%. The amount of high-boiling by-products was 8.68 g, and the piping was blocked six times during supplementation, and the piping was replaced each time.

Claims (1)

[Scope of Claims] 1. A catalyst represented by the following general compositional formula is used when producing a corresponding conjugated diolefin by oxidizing and dehydrogenating a monoolefin having 4 or more carbon atoms in the gas phase with molecular oxygen. A method for producing a conjugated diolefin, characterized by: Mo _a Bi _b Cr _{c Ni d Al e Fe f} Y is In, Ag, Ti, Nb, Ta,
Represents one or more elements selected from Co, La, Ce, Nd and Mn, a, b, c, d, e, f, g,
h and i are respectively Mo, Bi, Cr, Ni, Al, Fe,
The number of atoms of X, Y and O, when a = 12, b = 0.05 to 20, c = 0.05 to 20, d = 0.1 to 30,
e=0.01~20, f=0.01~20, g=0.001~20, h
=0 to 20, and i is the number of oxygen atoms that satisfies the valences of other elements. ) 2 When a=12, b=0.1~8, c=0.1~
10, d=1~20, e=0.05~10, f=0.05~10,
2. The method according to claim 1, wherein g=0.01 to 10 and h=0.01 to 10, and i is the number of oxygen atoms satisfying the valences of other elements. 3. The method according to claim 1, wherein the monoolefin has 4 to 6 carbon atoms. 4. The method according to claim 3, wherein the monoolefin is normal butene, isopentene or normal pentene.