JPH032126B2 - - 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.), multicomponent catalysts containing molybdenum, bismuth and chromium as essential components (e.g. JP-A-50-64191, etc.), and catalysts containing molybdenum, bismuth and zirconium as essential components. Multi-component catalyst (for example, JP-A No. 51-93793, etc.)
However, when using these catalyst systems, there is a large difference in reactivity between the isomers of monoolefin, which is the raw material. When this catalyst system was applied to a mixture of isomers, there was a drawback that the yield of the desired conjugated diolefin was drastically 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, although the use of these catalysts has the above advantages, the reaction temperature is rather high, the reactor material is expensive, and the reaction time is not long. If the process was continued, new problems were discovered, such as the tendency for the reaction system to become clogged 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 study to develop a catalyst that does not produce by-products, the present invention was completed. 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 composition Mo _a Bi _b Cr _{c Ni d Zr e Fe f} ,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, Zr, 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 0.05-5, g=
0.001-20, preferably 0.01-10, h=0-20,
It preferably takes a value of 0.01 to 5, where i is the number of oxygen atoms that satisfies 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 have to be used in an isolated form, but can be used in any mixture form as required. For example 1,3-
When trying to obtain butadiene, high-purity butene-1 or butene-2 can be used as a raw material, but _1,3
-Using 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. Even in that case, it is possible to obtain a yield equivalent to that obtained when a single highly purified raw material is used. In addition, when trying to obtain isoprene or 1,3-pentadiene, it is possible to similarly use a fraction containing isopentene as the main component or a distillate containing normal pentene as the main component. _Isoprene and 1,3-
Pentadiene can also be synthesized at the same time. 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
- Select zirconium from the Y components of the Bi-Cr-Ni-X-Y catalyst, and combine it with iron, which was considered to be a component to be excluded in the above publication, to make chromium, nickel, zirconium, and iron essential components. If any one of these four essential elements, chromium, nickel, and zirconium, is missing, the difference in reactivity between the monoolefin isomers cannot be resolved, and moreover, the high boiling point substance I can't even hold back my life. In addition, in the absence of iron, there is almost no difference in reactivity between monoolefin isomers, but the reaction temperature at which the same catalytic performance (diolefin yield) is obtained is higher, and high-boiling 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. The Y component and each element constituting the Y component have the same effect, but among them, K, Rb, Cs,
Tl, Ba, Zn, Cd and P, Al, 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 material 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 ammonium salts of each element, nitrates, carbonates, organic acid salts, salts such as halides, free acids, acid anhydrides, condensed acids, and molybdenum such as phosphomolybdic acid and silimolybdic acid. Examples include heteropolyacids and heteropolyacid salts such as ammonium salts and metal salts thereof. 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, zirconium, iron, and Y component are dissolved, the pH is adjusted to a range of 2 to 9 with 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. You can also do it.
As the carrier or diluent, known carriers or diluents may be used, such as titanium dioxide, silica gel, silica sol, diatomaceous earth, silicon carbide, alumina, pumice, silica-alumina, bentonite, zeolite, talc, refractories, etc., and in particular, carriers containing silicon. A carrier 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 hydrocarbons from reaction products). Furthermore, the reaction temperature is 250 to 700°C, preferably 300 to 600°C, the reaction pressure is normal pressure to 10 atm, and the space velocity (SV) of the total feed gas is 200 to 10000 hr ^-1 , preferably 300 to
6000hr ^-1 (STP standard), monoolefin concentration in feed gas is 0.5-30% by volume, monoolefin to oxygen ratio is 1:0.1-7, preferred feed gas composition is monoolefin:air:steam=1:2 ~30:0
~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, the catalyst system used in the present invention shows almost no difference in reactivity between the monoolefin isomers, and no decrease in activity is observed due to paraffins. It is suitable when using industrially inexpensively available fractions as raw materials, such as mixtures of We can obtain the conjugated diolefin with . In addition, the catalyst system used in the present invention has a long catalyst life and produces fewer high-boiling point substances that can clog the reactor outlet tube.
In addition, even if the catalyst strength is increased, the catalyst activity is not adversely affected, so the reaction can be carried out stably over a long period of time.It also has the advantage that the yield does not decrease even when the monoolefin concentration is increased and the space velocity is increased. have 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) ) x 100 Diolefin selectivity (%) = Corresponding conjugated diolefin produced (mol)/Reacted monoolefin (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 48.5g of bismuth nitrate, 26.7g of zirconyl nitrate,
4.04 g of ferric nitrate, 232.6 g of nickel nitrate, 45.6 g of chromium nitrate, and 2.02 g of potassium nitrate were added to 150 ml of water and dissolved under heating to form Solution A, and 212 g of ammonium molybdate was dissolved in 400 ml of warm water. This was used as liquid B. 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 pickler until it is sufficiently homogeneous.
This is 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 Zr 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 place in a metal bath.
Heated to 310℃, using each of the regular butenes having the composition shown in Table 1, the flow rate of the regular butene contained in these was 18 per hour (gaseous, NTP standard), and the flow rate of air was 132 per hour (NTP standard) It was passed through the catalyst layer in the following manner. 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] Comparative Example 1 Regarding catalyst No. (1) used in Example 1, Cr, Ni,
Comparative catalyst Nos. (c-1) to (c-7) were prepared in exactly the same manner except that Zr 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】

[Table] From this result, among the catalyst components, Cr, Ni,
It can be seen that if even one of Zr and Fe is missing, the catalyst 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 set to 350°C, excellent performance is shown, but when the metal bath in the reactor is set to 310°C as in this comparative example, the catalytic 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 Zr 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. As the catalyst raw material for the Y component, fine powder oxides are used for Nb and Ta, which are suspended in warm water and added to Solution A. For Ti, an aqueous chloride solution is added to Solution A, and other Y As for the ingredients, an aqueous nitrate solution was added to Solution A. 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 Fill a stainless steel reaction tube with an inner diameter of 2.5 cm and a length of 60 cm with 100 ml of the catalyst obtained in Example 1, heat it to 320°C in a metal bath, and perform BBRR using BBRR-1.
-1: Air: Water vapor = 15:53:32 (molar ratio) supply gas was passed for a contact time of 2 seconds (NTP standard), the reaction rate of normal butene contained in BBRR-1 was 93.8%, 1 , 3-butadiene yield 85.7%,
The 1,3-butadiene selectivity was 91.4%. Further, the amount of high-boiling by-products collected in the same manner as in Example 1 was 0.65 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 94.0%.
The 1,3-butadiene yield was 85.1%, and the 1,3-butadiene selectivity was 90.5%. Further, the amount of high-boiling by-products collected in the same manner as in Example 1 was 1.32 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 92.2%, and the yield of 1,3-butadiene was
The selectivity for 1,3-butadiene was 85.1% and 92.3%, which was substantially the same as the activity at the beginning of the reaction. Furthermore, the amount of high-boiling by-products was 0.85 g, which had decreased since the beginning of the reaction. During this period, we supplied
Although the components and composition of BBRR-1 varied considerably each time the raw materials were exchanged, 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 period of 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 77.9%, the isoprene yield was 67.1%, and the isoprene selectivity was 86.1%, and the reaction rate of normal pentene was 81.6%, 1,3-
The pentadiene yield was 71.2%, and the 1,3-pentadiene selectivity was 87.3%. The amount of high-boiling by-products measured in the same manner as in Example 1 was 0.88 g.

【table】

[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 collection, 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 Zr e Fe f} where Y is Al, In, Ag, Ti, Nb,
Represents one or more elements selected from Ta, Co, La, Ce, Nd and Mn, a, b, c, d, e,
f, g, h and i are respectively Mo, Bi, Cr, Ni,
The number of atoms of Zr, Fe, X, Y and O, a=12
In this case, b=0.05~20, c=0.05~20, d=
0.1~30, e=0.01~20, f=0.01~20, g=
It takes a value of 0.001 to 20, h=0 to 20, and i is the number of oxygen atoms satisfying the valences of other elements. )