JPH024583B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for selectively reacting isobutylene from an olefin mixture containing n-butene and isobutylene to oligomerize it. Isobutylene oligomers are used as octane improvers for automobile fuels, dispersants for pigments, and raw materials for the synthesis of octylphenol, octyl diphenylamine, dinonyl phthalate, and the like. Conventionally, the sulfuric acid method and the ion exchange resin method have been known as industrial methods for producing isobutylene oligomers, but the sulfuric acid method has corrosion problems and is not easy to separate from the reaction mixture, so recently ion exchange methods have been used. Resin methods are becoming more common. However, this method had the drawbacks of low activity and short life of the resin. As a result of intensive research aimed at obtaining a catalyst that has a high isobutylene oligomer production activity and does not oligomerize n-butene, the present inventors have found that they can be dehydrated at a temperature lower than the decomposition temperature of heteropolyacids and/or heteropolyacids. When a heteropolyacid and/or a heteropolyacid salt that has been treated to reduce its water of hydration (water of crystallization) is reacted at 120°C or lower, isobutylene is reacted selectively over an olefin mixture containing n-butene and isobutylene. It was discovered that isobutylene oligomers can be produced. It has been known that the oligomerization of olefin compounds proceeds at 300 to 400°C in the gas phase using a "phosphotungstic acid-alumina" catalyst (T. Yamamura, J. Sci. Hiroshima Univ.,
Ser.A Vol.39, No.1, pp93-110, April 1975).
However, under these conditions, not only isobutylene but also ethylene, propylene, and n-butene are oligomerized, and by-products such as pentene are also produced. On the other hand, the present inventors have already discovered that tertiary-butanol can be produced by reacting a heteropolyacid aqueous solution with a mixture of n-butene and isobutylene, but it has been confirmed that only a very small amount of diisobutylene etc. is produced at that time. are doing. However, when a heteropolyacid and/or a heteropolyacid salt is prepared under water-free conditions, especially using a catalyst from which water of hydration has been removed, it is surprisingly possible to heat the heteropolyacid and/or heteropolyacid at 120°C or lower, preferably at 40°C.
The inventors discovered that isobutylene can be quickly oligomerized even at low temperatures of 80°C to 80°C, leading to the present invention. That is, the present invention provides for the selective oligomerization of isobutylene from an olefin mixture containing n-butene and isobutylene, using hydration water ( The present invention relates to a method for producing isobutylene oligomers, which is characterized by using a heteropolyacid and/or a heteropolyacid salt with a reduced amount (water of crystallization) and carrying out the reaction at 120°C or lower. The isobutylene oligomer produced in the present invention is mostly an isobutylene dimer, and also contains a small amount of a trimer, but there are very few tetramers or more. The olefin mixture used in the present invention is n
- Contains butene and isobutylene,
Depending on the case, propylene, ethylene, saturated hydrocarbons, aromatic hydrocarbons, etc. may be included.
It may also contain a small amount of butadiene and/or pentenes. Such olefin mixtures include, for example, so-called spent olefins containing isobutylene and n-butene as main components obtained after removing butadiene from a C4 fraction in a naphtha cracking process.
BB, spent BB by removing most of the isobutylene from BB, so-called spent spent BB, which is mainly n-butene and containing a small amount of isobutylene, contact with C ₄ fraction, a by-product of petroleum fluid catalytic reaction equipment, and n-butane. There are dehydrogenated fractions, etc. A particularly preferred example of application of the present invention is the case where almost all of the small amount of isobutylene (bp-6.90°C) contained in spent BB is oligomerized. Using this application example, isobutylene (bp - 6.90°C) in spent BB can be removed and the residual olefin mixture can easily be purified by distillation.
-Butene (bp-6.25℃) can be obtained. The heteropolyacid used in the present invention contains molybdenum and/or tungsten as a coordination element, and vanadium may be partially substituted. When using vanadium, the atomic ratio is 1/1 to molybdenum and/or tungsten.
6 to 1/12 vanadium is used. The central element is at least one of phosphorus, silicon, arsenic, germanium, boron, titanium, cerium, thorium, manganese, nickel, tellurium, iodine, cobalt, chromium, iron, gallium, vanadium, platinum, beryllium, and zinc. seeds are used,
Particularly preferred is at least one of phosphorus, silicon, and germanium. Further, the number of atoms of the central element is 1 or 2, preferably 1. Also, the number of atoms of the coordination element is equal to the number of atoms of the central element.
2.5 times to 12 times, preferably 11 times to 12 times is used. Specific heteropolyacids include, for example, phosphomolybdic acid, silicomolybdic acid, germanomolybdic acid, phosphotungstic acid, silicotungstic acid, germanotungstic acid, phosphomolybdotungstic acid, phosphovanadotungstic acid,
Borotungstic acid and the like are used, and phosphomolybdic acid and silicotungstic acid are particularly preferred. As the heteropolyacid salts used in the present invention, the periodic table a, b of the above-mentioned heteropolyacids,
Salts of metals selected from the group a, b, a, b, a, a, a, iron, cobalt, nickel, lead, bismuth are used, most preferably sodium salts. Further, among the heteropolyacids and/or heteropolyacid salts, heteropolyacids are preferred, and phosphomolybdic acid and tungstic silicoic acid are particularly preferred. Before using the heteropolyacid and/or the heteropolyacid salt in the reaction of the present invention, it is necessary to dehydrate the heteropolyacid and/or the heteropolyacid salt to remove part or all of the water of hydration. If a heteropolyacid and/or a heteropolyacid salt with hydration water still attached is used, the hydration water will react with isobutylene and tertiary butanol will be generated simultaneously with the oligomer, so the heteropolyacid and/or heteropolyacid salt will be dehydrated. is necessary. Dehydration treatment methods include (1) removing water of hydration by heating, (2) removing water of hydration by bringing it into contact with something that reacts with water of hydration, such as isobutylene or an olefin mixture. There is a way. In addition, the amount of hydration water to be removed is not necessarily a fixed value; if the heteropoly structure is stable, all hydration water may be removed, or some hydration water may be left behind. If the water does not react with isobutylene, some of the water of hydration may be left behind. When removing water of hydration by heating, dehydration must be performed at a temperature lower than the decomposition temperature of the heteropolyacid and/or heteropolyacid salt in order to prevent decomposition of the heteropolyacid. For this purpose, the heat treatment is preferably carried out at a temperature that is at least 50°C to 100°C lower than the decomposition temperature of the heteropolyacid and/or heteropolyacid salt. The decomposition temperature of heteropolyacids and/or heteropolyacids varies depending on the type of heteropolyacid, but is between 250℃ and 400℃.
Many are in the range. Therefore, the dehydration temperature is generally selected from a range not exceeding 350°C. It is more preferable to process phosphomolybdic acid and silicotungstic acid at 320°C or lower;
All hydration water can be removed by dehydration at 320°C. These catalysts may be used alone as they are, supported on a carrier inert to the reaction, or coated on the reaction tube wall. In the reaction of the present invention, solvents inert to the reaction, such as saturated hydrocarbons, aromatic hydrocarbons, etc., can be used, but water cannot be used. As mentioned above, the presence of water will result in the formation of tertiary butanol, so in the present invention it is necessary to dehydrate the catalyst and to prevent the presence of water in the mixed olefin. Regarding the temperature conditions used for the reaction of the present invention, oligomerization of n-butene tends to occur if the reaction is carried out at a temperature of 120°C or higher, so it is necessary to carry out the reaction at a temperature of 120°C or lower. It is characterized by a fast reaction rate. Further, the reaction pressure is not particularly limited, but it is preferable that the reaction pressure be at least the pressure necessary to maintain the liquid phase of the olefin mixture because the reaction rate is fast. Further, in the reaction of the present invention, an inert solvent can also be used. As an embodiment of the present invention, either a batch method or a continuous method may be used, and a stirring tank may be used or the catalyst may be a fixed bed. Example 1 Phosphormolybdic acid (Wako Pure Chemical Industries, reagent special grade)
5 g of isobutylene and 5 g of isobutylene were placed in a 50 ml stainless steel autoclave and stirred at 70°C for 2 hours at 13 kg/cm ² G.
The catalyst was dehydrated by removal under Hg. Next, isobutylene 3.3 mol%, n-butene 58.9 mol%, butane 37.2 mol%, propane 0.1
When 5 g of an olefin mixture consisting of 0.1 mol % of pentane and 0.4 mol % of butadiene was added to an autoclave and stirred at 70° C. and 14 kg/cm ² G for 1 hour, only isobutylene became an oligomer.
At this time, the isobutylene reaction rate was 99.3%, the n-butene reaction rate was 0%, and the oligomer selectivity was 99.9%. Comparative Example 1 Phosphormolybdic acid (Wako Pure Chemical Industries, Ltd.,
Example 1 except that 5 g of reagent (special grade) was used as it was.
As a result of reacting under exactly the same conditions, the isobutylene reaction rate was 99.2% and the isobutylene oligomer selectivity was
The selectivity for tertiary butanol was 34.7% and 65.2%. Example 2 Phosphormolybdic acid (Wako Pure Chemical Industries, reagent special grade)
5 g of catalyst dehydrated by calcining in air at 110°C for 2 hours, 47.1 mol% of isobutylene, 26.2 mol% of 1-butene, 14.3 mol% of 2-butene, 11.8 mol% of butane, 0.1 mol% of propane. ,
When 5 g of an olefin mixture consisting of 0.1 mol% pentane and 0.4 mol% butadiene was placed in a 50 ml stainless steel autoclave and stirred for 1 hour at 80°C and 14 kg/cm ² G, only isobutylene became an oligomer, and the isobutylene reaction rate was 98.1%. -Butene reaction rate was 0% and oligomer selectivity was 99.1%. Examples 3 to 5 Comparative Example 2 5 g of phosphomolybdic acid dehydrated under the same conditions as in Example 1 and 5 g of the same olefin mixture as in Example 1 were placed in a 20 ml stainless steel autoclave and heated at 40°C at 5 kg/cm ² G. , 100℃ 19Kg/cm ² G, 120
Table 1 summarizes the results of stirring for 1 hour at 28 Kg/cm ² G at 140° C. and 37 Kg/cm ² G at 140° C.

【table】

[Table] Examples 6 to 11 Silicomolybdic acid, germanomolybdic acid, phosphotungstic acid, silicotungstic acid, sodium phosphomolybdate, and cobalt phosphomolybdate were calcined in air at 200°C for 2 hours and dehydrated. 5 g and 5 g of the same olefin mixture as in Example 1 were placed in a 50 ml stainless steel autoclave and stirred at 70° C. and 11 kg/cm ² G for 1 hour. The results are summarized in Table 2.

【table】

【table】

Claims (1)

[Claims] 1 When selectively oligomerizing isobutylene from an olefin mixture containing n-butene and isobutylene, water of hydration (water of crystallization) is reduced by dehydration treatment at a temperature lower than the decomposition temperature of the heteropolyacid and/or heteropolyacid salt. A method for producing an isobutylene oligomer, which uses a heteropolyacid and/or a heteropolyacid salt, and is characterized in that the reaction is carried out at 120°C or lower.