JPS6254406B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for selectively underpolymerizing isobutene using a high silica mordenite catalyst having a specific amount of solid acid, and more specifically, the present invention relates to a method for selectively underpolymerizing isobutene in a coexisting isobutene-containing hydrocarbon component. The present invention relates to a method of selectively underpolymerizing only. BACKGROUND ART As a method for polymerizing isobutene in a hydrocarbon mixture containing isobutene to form a low polymer,
A method of contacting with a solid acid catalyst such as silica/alumina, zeolite, or cation exchange resin has been known for some time, and is used to remove isobutene from C ₄ hydrocarbons. For example, a _C4 hydrocarbon mixture is brought into contact with an isomerization catalyst such as palladium, platinum, or nickel to isomerize 1-butene to 2-butene, and then brought into contact with a solid acid catalyst such as activated clay or silica/alumina. , a method of low polymerizing isobutene and separating and removing the resulting low polymer (Japanese Unexamined Patent Application Publication No. 1982-8201),
A method of removing isobutene by contacting it with a crystalline molecular sieve (10× molecular sieve) having an effective pore opening of about 8 Å to about 8.2 Å (Japanese Patent Publication No. 47-42803), synthetic zeolite (ZSM-4) and A method in which isobutene is selectively low-polymerized by contacting the isobutene (Japanese Patent Publication No. 51-29121), and a method in which isobutene is low-polymerized by supplying it to a distillation column filled with a cation exchange resin and is separated and removed from the bottom of the column ( US Patent No.
4215011) etc. are known. However, in either method, the 1-butene contained in the C ₄ hydrocarbon mixture is isomerized to 2-butene, so these methods are unsuitable for producing 1-butene that does not contain isobutene. Summary of the Invention The present inventors have conducted studies aimed at developing a catalyst that selectively polymerizes only isobutene and does not exhibit any activity for isomerizing 1-butene to 2-butene. At the same time, by using the catalyst of the present invention, isobutene contained as an impurity in 1-butene is selectively polymerized and separated and removed as a low polymer of isobutene, thereby eliminating the loss of 1-butene. This method succeeded in effectively removing isobutene from 1-butene. That is, in the present invention, hydrogen exchange type or hydrogen exchange type precursor mordenite is hydrothermally treated in the presence of steam, and then brought into contact with an acid. mordenite catalyst with a silica/alumina (molar ratio) of 50 to 200 (hereinafter,
It is sometimes called a solid acid catalyst. ) with a hydrocarbon mixture containing isobutene and 1-butene. Solid Acid Catalyst The solid acid catalyst used in the present invention has a pyridine adsorption amount of 0.05 to 0.25 mmol per 1 g of solid acid catalyst, which can be measured by the pyridine adsorption method, and is a relatively low olefin. When carbon is activated to form carbonium ions, only tertiary carbon can be selectively activated. Silica/alumina ratio with controlled solid acid content is 50
~200 high silica mordenite catalysts selectively polymerize only isobutene and 1-butene to 2-
Shows no activity in isomerization to butenes. High-silica-containing mordenite with controlled solid acid content The high-silica-containing mordenite catalyst with controlled solid acid content used in the present invention is generally a natural or synthetic mordenite having the following unit cells: 4Na ₂ O・4Al It is obtained by converting ₂ O ₃ .4OSiO ₂ .24H ₂ O into a hydrogen exchange type or hydrogen exchange precursor, followed by hydrothermal treatment at high temperature in the presence of steam, and further aluminum extraction with a strong acid. This hydrothermal reaction involves heat treatment in the presence of water vapor, and the silica/alumina ratio can be adjusted to 50 to 50 by appropriately selecting the water vapor partial pressure and treatment temperature.
200 and the amount of solid acid can be controlled. In order to make the amount of pyridine adsorbed per gram of catalyst of high silica mordenite 0.05 to 0.25 mmol, the water vapor partial pressure during hydrothermal treatment should be 1% to 60%, preferably 5% to 40%, and the treatment temperature should be 600℃～1000
℃, preferably 650°C to 750°C. At temperatures below this range, the amount of solid acid cannot be controlled. In addition, in the absence of steam, only mordenite with a large amount of solid acid can be obtained, and if the partial pressure of steam is greater than this range, reactions other than dealumination are likely to occur, resulting in a significant reduction in the amount of solid acid. Hydrothermal treatment time is 1 to 10 hours, preferably 2 to 5 hours.
Its effects can be fully demonstrated over time. The acid extraction treatment that follows the hydrothermal treatment is performed to remove AlOH ²⁺ that has been separated from the mordenite skeleton structure by the hydrothermal treatment and is present in the cavities and aluminum atoms that are located in a relatively weak skeleton structure. Acids used in acid extraction include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid; organic acids such as acetic acid, acetic chloride, acetic acid trichloride, citric acid, tartaric acid,
Oxalic acid etc. can be used. Of these, mineral acids such as hydrochloric acid, sulfuric acid and nitric acid are preferably used. Further, when using these acids for extraction treatment, it is preferable to use those with a concentration of 4N or more, preferably 6N or more. The acid extraction treatment is preferably carried out at a temperature range from room temperature to 100°C. Acid extraction-treated mordenite must be calcined under conditions milder than the hydrothermal treatment at 400°C to 700°C, preferably 500°C to 600°C, to stabilize the unstable crystalline state. The thus obtained high silica-containing mordenite with a pyridine adsorption amount of 0.05 to 0.25 mmol per gram of mordenite and a silica/alumina ratio of 50 to 200 can be used as a reaction catalyst in the present invention as it is or after being shaped. can. Pretreatment The high-silica-containing mordenite used as a catalyst in the present invention is characterized by little deterioration in catalytic performance even after long-term use. By contacting the catalyst at a temperature higher than the reaction temperature, the activity of the catalyst can be maintained for a longer period of time. The hydrocarbon used in the pretreatment may be any hydrocarbon, but unsaturated hydrocarbons such as olefins, diolefins, aromatic hydrocarbons, etc. are preferable, and it is particularly advantageous for operation to use a hydrocarbon mixture as a raw material. be. Pretreatment is preferably carried out in a liquid phase or gas phase at a temperature higher than the reaction temperature of the main reaction (catalytic reaction of raw material hydrocarbons) and below 300°C for 10 minutes to 5 hours. Temperature 140-200℃, reaction time
It is preferable to carry out the reaction for 0.5 to 2 hours at a liquid hourly space velocity (LHSV) of ¹ to 20 hours. Hydrocarbon mixture The hydrocarbon mixture used in the present invention can be any mixture as long as it contains isobutene and 1-butene. A mixture of C ₄ hydrocarbons obtained by pyrolysis of petroleum, a butane-butene fraction obtained by removing butadiene from the C ₄ fraction produced as a by-product during the production of ethylene by thermal decomposition of petroleum, or a mixture of hydrocarbons containing n-butane and isobutane. C ₄ hydrocarbon mixtures obtained by dehydrogenation of C 4 and the like are advantageously used. These _C4 hydrocarbon mixtures are used as is. These hydrocarbons usually include n-butene (1-butene, trans-2-butene, cis-2-butene) and isobutene, as well as n-butane, isobutane, butadiene and trace amounts of C ₃ hydrocarbons and
Contains _C5 hydrocarbons. The content of each of these components is
Although not particularly limited, when the purpose is to produce high-purity 1-butene, at least 20 mol% of n-
Preference is given to using butenes, hydrocarbon mixtures containing from 0.1 to 50 mol % isobutene. Isobutene polymerization conditions A low polymer of isobutene can be obtained by contacting isobutene with the mordenite catalyst according to the present invention, and the polymerization conditions include gas phase or liquid phase reaction, reaction temperature 20 to 180°C, reaction pressure. Atmospheric pressure ~100
Kg/ ^cm2 , preferably liquid phase reaction, reaction temperature
The temperature is 60 to 140°C, and the reaction pressure is usually 10 to 50 kg/cm ² at a pressure that can maintain a liquid phase. In addition, in the case of liquid phase reaction
The LHSV is from 0.01 to 50 h ^-1 , preferably from 0.1 to 10 h ^-1 for the raw material. According to the present invention, isobutene contained in the raw material becomes almost completely a dimer, trimer or higher low polymer, but 1-butene is hardly isomerized. The low polymerized isobutene is further separated and removed, but the method is not specified and any known method may be used. By doing this, it is possible to obtain a fraction containing almost no isobutene, but the method for recovering and separating 1-butene and/or 2-butene from this fraction is normally carried out without adopting any specific method. You can do it using the method provided. Effects of the Invention According to the method of the present invention, isomerization of isobutene contained in a raw material hydrocarbon mixture is almost complete without causing almost no isomerization of 1-butene to 2-butene and loss of n-butene. In addition, isobutene can be converted into a dimer, trimer, or higher low polymer that can be easily separated from _C4 hydrocarbons, and isobutene can be completely removed by combining the process of removing the low polymer. can. Therefore, high purity 1-butene and/or almost no isobutene can be obtained from the fraction from which the polymer has been removed.
Or 2-butene can be recovered. According to the method of the present invention, it is possible to selectively underpolymerize isobutene without isomerizing 1-butene, and this isobutene underpolymer can be easily separated from 1-butene. It can be used as a method for purifying butene. The drawing shows an example. In FIG. 1, a 1-butene fraction containing isobutene as an impurity is supplied from a pipe 11 to an isobutene polymerization tank 1 filled with a catalyst with a controlled amount of solid acid, and the 1-butene fraction containing isobutene as an impurity is After selectively underpolymerizing the isobutene contained therein, it is extracted from the pipe 12. Further, the isobutene is sent from the pipe 21 to the second stage isobutene polymerization tank 2, which is also filled with a catalyst with a controlled amount of solid acid, and the remaining isobutene is subjected to low polymerization. Then, 1- containing a low polymer of isobutene
The butene fraction is sent to the distillation column 3 through a pipe 31, and by distillation, low polymers of isobutene are extracted from the pipe 33, and high-purity 1-butene containing almost no isobutene is extracted from the pipe 32. Separated and collected. In Figure 1, an example using two isobutene polymerization tanks has been explained, but if the content of isobutene is a trace amount, even one isobutene polymerization tank can suffice for the purpose. Depending on the situation, it is also possible to use three or more. When 2-butene is included in the 1-butene fraction of the raw material, the method for separating 1-butene and 2-butene is as shown in FIG. The operation conditions of the distillation column 3 are set accordingly. Alternatively, a distillation column 3 designed to extract 2-butene from tube 34 as shown in FIG. 2 may be used. Furthermore, in FIG. 1, the mixture of isobutene low polymer and 2-butene extracted from the pipe 33 is
By supplying the distillation column 4 through a tube 41 as shown in the figure, 2-butene can be easily separated from the tube 42 and low polymers of isobutene can be easily separated from the tube 43 by distillation. EXAMPLES Next, the present invention will be specifically explained using examples and comparative examples. However, the present invention is not limited only to the examples. Note that percentages (%) in Examples and Comparative Examples are mol% unless otherwise specified. Example 1 Preparation of catalyst for high silica-containing mordenite 100 g of 1/16 inch pellets of commercially available highly crystalline sodium mordenite (manufactured by Norton, trade name: Zeolon 900Na) were immersed in 500 ml of 1N hydrochloric acid at 80°C.
The mixture was stirred for 1 hour. After completion, the acid solution was removed by the decanting method, and 500 ml of fresh 1N hydrochloric acid was poured into the solution, followed by stirring at 80° C. for 1 hour. After removing the hydrochloric acid solution, the sample was washed with warm water until no chlorine ions were detected. Next, hot air drying was performed at 110°C to obtain a hydrogen ion exchange type mordenite precursor. The obtained hydrogen ion exchange type precursor was heated gradually from room temperature under a water vapor partial pressure of 30% and subjected to hydrothermal treatment at 650° C. for 4 hours. After cooling, use 500ml of 12N hydrochloric acid to 90%
Reflux treatment was performed at ℃ for 6 hours to extract aluminum. After removing the hydrochloric acid solution, the sample was washed with warm water until no chlorine ions were detected, and then dried with hot air at 110°C. After air drying, heat at 650℃ using a Matsufuru furnace.
After firing for a period of time, a high silica-containing mordenite was obtained. The composition and silica/alumina ratio of the obtained mordenite had the values shown in the table. The obtained high silica content type mordenite is
It was ground into 100 meshes and baked at 500°C for 1 hour to remove adsorbed components, and 0.075g was accurately weighed and charged into a reactor. On the other hand, a bubbler containing pyridine was immersed in a water bath maintained at a constant temperature of 15.5°C, and nitrogen was bubbled to adsorb pyridine onto the catalyst packed in the reactor at room temperature. Next, the temperature of the reactor was gradually raised to 300°C under nitrogen flow, and the temperature was maintained at 300°C until the physically adsorbed pyridine was desorbed. After that, gas chromatography confirmed that pyridine desorption was no longer observed, and the reactor was heated at a heating rate of 10°C/min.
The temperature was raised from 300°C to 950°C, and the desorbed pyridine was quantified by gas chromatography. The amount of pyridine released is proportional to the amount of solid acid in mordenite. The results are shown in the table. Catalytic reaction A cylindrical reactor filled with the catalyst obtained above was filled with 26.2% butane, 1.3% isobutene, and 7.5% 1-butene.
%, and a _C4 hydrocarbon mixture consisting of 65% 2-butene, the reaction temperature was 80℃, and the reaction pressure was 35Kg/ ^cm2.
(pressurized with nitrogen gas) and LHSV 3.0 h ^-1 . The results of analysis of the hydrocarbon mixture at the reactor outlet 16 hours after the start of the reaction are shown in the table. Further, the conversion rate of isobutene was tracked as the reaction time progressed, and the deterioration coefficient α was determined from K=K ₀ e 〓 ^t . Here, K is the isobutene dimerization reaction rate constant at time t, K ₀ is the initial reaction rate constant determined by extrapolation, and α is the deterioration coefficient. The results are shown in the table. Comparative Example 1 The hydrogen ion exchange type precursor obtained in Example 1 was calcined at 650° C. for 4 hours using a Matsufuru furnace, and then extracted with hydrochloric acid and calcined in the same manner as in Example 1 to obtain a mordenite catalyst. The pyridine adsorption amount and composition of the catalyst, and the silica/alumina ratio are shown in the table. A catalytic reaction similar to that in Example 1 was carried out using this catalyst, and the results are shown in the table. Comparative Example 2 The water vapor partial pressure was reduced to 100 in the hydrothermal treatment in Example 1.
%, a mordenite catalyst was prepared in the same manner as in Example 1, except that the treatment temperature was 700° C. and the treatment time was 3 hours, and a catalytic reaction was carried out. The results are shown in the table. Comparative Example 3 The water vapor partial pressure was reduced to 65 by the hydrothermal treatment in Example 1.
%, a mordenite catalyst was prepared in the same manner as in Example 1, except that the treatment temperature was 650° C. and the treatment time was 3 hours, and a catalytic reaction was carried out. The results are shown in the table. Example 2 A catalyst was prepared in the same manner as in Example 1, except that nitric acid was used instead of hydrochloric acid in the acid treatment in Example 1, and a catalytic reaction was performed. The results are shown in the table. Example 3 A catalyst was prepared in the same manner as in Example 1 except that sulfuric acid was used instead of hydrochloric acid in the acid treatment in Example 1, and a catalytic reaction was performed. The results are shown in the table. Example 4 Preparation of catalyst 67g of aluminum sulfate and concentrated sulfuric acid in 1500g of pure water
Dissolve 19.7g of sodium chloride and 140g of sodium chloride, add 490g of water glass (No. 3), and dissolve 2.5Na ₂ O.
An aqueous reaction mixture was obtained having the composition Al ₂ O ₃ .23SiO ₂ .99H ₂ O. After this mixture was aged at room temperature for about 1 hour, it was put into an autoclave, the temperature was rapidly raised, and the temperature was maintained at 180°C for 20 hours. The obtained solid product was cooled to room temperature, filtered, thoroughly washed with water, and then dried at 110°C. A part of the product was calcined in air at 700°C, water was adsorbed at room temperature, and chemical analysis was performed to obtain synthetic mordenite with the following composition. Loss on ignition at 800°C 10.0% by weight SiO ₂ 79.1 Al ₂ O ₃ 5.96 Na ₂ O 3.51 SiO ₂ /Al ₂ O ₃ (molar ratio) 22.6 It was confirmed from the spacing that it had a mordenite crystal structure. 100 g of the obtained synthetic mordenite was treated in exactly the same manner as in Example 1 to obtain highly silica-containing mordenite. The composition and adsorption amount of pyridine were as follows. Composition Loss on ignition at 800℃ 3.2% by weight SiO ₂ 95.1〃 Al ₂ O ₃ 1.22〃 Na ₂ O 0.11〃 SiO ₂ /Al ₂ O ₃ (mole ratio) 133 Pyridine adsorption amount (mmol/g mordenite) Total pyridine adsorption amount 0.108 Contact Reaction A catalytic reaction was carried out in the same manner as in Example 1 using this catalyst. The results are shown in the table. Example 5 The water vapor partial pressure was reduced to 5 by the hydrothermal treatment in Example 1.
%, a mordenite catalyst was prepared in the same manner as in Example 1, except that the treatment temperature was 700° C. and the treatment time was 3 hours, and a catalytic reaction was carried out. The results are shown in the table. Example 6 The water vapor partial pressure was reduced to 20 by the hydrothermal treatment in Example 1.
%, a mordenite catalyst was prepared in the same manner as in Example 1, except that the treatment temperature was 700° C. and the treatment time was 3 hours, and a catalytic reaction was carried out. The results are shown in the table. Comparative Example 4 The hydrogen ion exchange type precursor obtained in Example 1 was
C. for 3 hours in a Matsufuru furnace to obtain hydrogen ion exchange type mordenite. A catalytic reaction was carried out in the same manner as in Example 1 using this catalyst. The results are shown in the table. Example 7 The catalyst obtained in Example 5 was retreated under the same hydrothermal treatment conditions as in Example 5 to prepare a catalyst, and a catalytic reaction was performed. The results are shown in the table. Example 8 The water vapor partial pressure was reduced to 45 by the hydrothermal treatment in Example 1.
A catalyst was prepared in the same manner as in Example 1, except that the treatment temperature was 660° C. and the treatment time was 4 hours, and a catalytic reaction was carried out. The results are shown in the table. Example 9 The water vapor partial pressure was reduced to 20 by the hydrothermal treatment in Example 1.
%, a catalyst was prepared in the same manner as in Example 1, except that the treatment temperature was 630° C. and the treatment time was 3 hours, and a catalytic reaction was carried out. The results are shown in the table. Example 10 The water vapor partial pressure was reduced to 45 by the hydrothermal treatment in Example 4.
%, a catalyst was prepared in the same manner as in Example 4, except that the treatment temperature was 660° C. and the treatment time was 4 hours, and a catalytic reaction was carried out. The results are shown in the table. 【table】

[Brief explanation of the drawing]

Figure 1 is a schematic process diagram for industrially carrying out the method using the catalyst of the present invention, and Figures 2 and 3 are process diagrams of a method for separating each component after being treated by the method of the present invention. It is. 1 and 2...isobutene polymerization tank, 3 and 4...
Distillation tower.

Claims (1)

[Claims] 1 obtained by hydrothermally treating hydrogen exchange type or hydrogen exchange type precursor mordenite in the presence of steam and then contacting it with an acid, the amount of pyridine adsorbed is 0.05 to 0.25 mmol of solid acid per 1 g of catalyst, And silica/alumina (molar ratio) is 50~
200 mordenite catalyst with isobutene and 1-
A process for the underpolymerization of isobutene in a hydrocarbon mixture containing butene, the process comprising contacting the mixture with said hydrocarbon mixture.