JPH0240376B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides an isomerization catalyst for linear aliphatic olefins,
In particular, the present invention relates to an isomerization catalyst in which a halogen is supported on high-purity activated alumina (hereinafter referred to as Ziegler alumina) obtained as a by-product in the Ziegler method for higher alcohol synthesis, and a method for producing the same. Currently, a large amount of aliphatic olefins are industrially produced from plants such as naphtha thermal cracking or gas oil fluid catalytic cracking plants, and among these aliphatic olefins, aliphatic olefins with less branching are classified into those with more branches. It is highly desirable to isomerize to aliphatic olefins or from more branched aliphatic olefins to less branched aliphatic olefins. For example, after separating butadiene and isobutene from the _C4 fraction produced by the plant, the n-butene-containing fraction can be skeletal isomerized into useful isobutene. Isobutene is a useful compound that is or may be used in a wide variety of applications, including butyl rubber and methacrylic acid, a raw material for the production of polybutene, and a raw material for the production of methyl tert-butyl ether, which is useful as an auxiliary fuel for automobiles. be. Conventionally, various phosphoric acid catalysts, halogenated aluminas, boronated aluminas, various silicas, aluminas, and various sulfate catalysts have been proposed as effective catalysts for increasing the branching of aliphatic olefins.
The results are still unsatisfactory, and up to now,
No satisfactory catalyst has been found which is suitable for converting straight-chain aliphatic olefins, in particular C ₄ or C ₅ straight-chain aliphatic olefins, into the corresponding branched-chain aliphatic olefins on an industrial scale. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a catalyst suitable for isomerizing a less branched aliphatic olefin to a more branched aliphatic olefin with satisfactory results, and a method for producing the same. A more specific object of the present invention is to provide an isomerization catalyst that isomerizes normal butene to give isobutene, or isomerizes normal pentene to give isopentene, and a method for producing the same, with satisfactory results. The purpose of the present invention is to obtain high-purity active aluminum hydroxide produced as a by-product in the Ziegler method higher alcohol synthesis by calcining it at 500°C to 750°C, with a specific surface area of 150m ² /g to 250m ² /g. It consists of alumina and fluorine and chlorine supported on the activated alumina, and the amount of supported fluorine and chlorine is 0.2 to 2.0% for fluorine and 0.2 to 4.0% for chlorine, based on the weight of the total catalyst. This is achieved by an isomerization catalyst composition that converts straight chain aliphatic olefins into branched aliphatic olefins. Further, the catalyst composition of the present invention is obtained by calcining aluminum hydroxide produced as a by-product in the Ziegler process higher alcohol synthesis at 500°C to 750°C, and has a specific surface area of 150 m ² /g to 750°C.
A catalyst is produced by contacting a 250 m ² /g high-purity activated alumina carrier with one or more halogenated hydrocarbons containing fluorine and chlorine in the molecule at a temperature of 200 to 500°C. based on the total weight of
It can be produced by converting a straight-chain aliphatic olefin into a branched aliphatic olefin, in which 0.2-2.0% fluorine and 0.2-4.0% chlorine are supported on activated alumina. The Ziegler alumina used in the present invention is typically a by-product obtained from the Ziegler method higher alcohol synthesis reaction described in US Pat. No. 2,892,858. A general synthesis method is shown below. (1) Production of triethylaluminum (a) 2Al(C ₂ H ₅ ) ₃ +Al+1 1/2H ₂ →3AlH(C ₂ H ₅ ) ₂ (b) 3AlH(C ₂ H ₅ ) ₂ +3C ₂ H ₄ →3Al( C ₂ H ₅ ) ₃ (2) Synthesis of higher alkyl aluminum (linear growth reaction) (3) Oxidation of growth products (synthesis of higher alkyl aluminum oxides) (4) Hydrolysis of alkyl aluminum oxide Furthermore, according to US Pat. No. 2,892,858, high purity alumina can be obtained by removing water from the aluminum hydroxide paste obtained from the hydrolysis process. The extremely high purity of this Ziegler alumina is due to the fact that the triethylaluminum obtained in step (1) described above is purified by distillation. Ziegler alumina is available from Condeia of West Germany under the trade names "Pural" and "Dispural". This material is extremely pure boehmite (α-AlOOH), and when fired at high temperatures, most of it becomes γ-alumina and a small amount becomes η-alumina. It is currently available in four forms: (1)
Pural SB spray-dried product, (2) Pural NG
Rotary kiln dried product, (3) Dispural aluminum hydroxide which produces a colloidal dispersion with hydrochloric acid or nitric acid, (4) Dispural special aluminum hydroxide which produces a colloidal dispersion by adding water. In addition, Pural SCC, Pural SCW and Pural NW with uniform particle size are available as special grades.
is also available. The method for producing the alumina support of the present invention from boehmite (α-AlOOH) powder, which is Ziegler alumina hydroxide, is generally carried out by a well-known method. For example, boehmite powder may be moistened with water or acid and then extruded using a known method, or the powder may be compressed into tablets, or water or acid may be added to deflocculate the powder, and then a gelling agent may be added. A known method is to drop particles into heated oil to obtain spherical particles. Further, the boehmite powder can be formed into pellets, extrudates, granules, or spheres by methods known to catalyst manufacturers. These molded Ziegler aluminum hydroxides are fired and activated to form alumina in a conventional manner. The calcination is carried out at a temperature between 500° C. and 750° C. so that the specific surface area of the alumina is between 150 m ² /g and 250 m ² /g. Furthermore, in the present invention, the content of Ziegler alumina as well as Ziegler alumina is at least 50 mol%.
Other inorganic oxides can be used in combination in amounts. Examples of inorganic oxides that can be used in combination with Ziegler alumina include silica, titania, zirconia, magnesia, chromia, thoria, molybtena, tungsten oxide, and iron oxide, and one or more of these are preferably used. . Furthermore, Ziegler alumina and these compounds may be a mere physical mixture, and may also include, for example, silica, alumina, zirconia, alumina, magnesium-alumina (spinel), chromia-alumina, tria-alumina, alumina-alumina, etc.
It may also be a material that has a chemical bond with Ziegler alumina, such as molybdena. The catalyst of the present invention has a carrier composed of the above-mentioned Ziegler alumina or the Ziegler alumina and other inorganic oxide, and contains 0.2 to 2.0 fluorine based on the total weight of the catalyst.
% by weight, preferably 0.5-1.5% by weight, and chlorine
The amount supported is 0.2 to 4.0% by weight, preferably 0.5 to 3.0% by weight. Fluorine and chlorine can be easily supported on the carrier by treating the Ziegler alumina or a carrier made of the Ziegler alumina and other inorganic oxides with a halogenated hydrocarbon containing fluorine and chlorine. However, before the treatment, the carrier is left in a moisture-containing gas, such as nitrogen or air, at a temperature between room temperature and 100°C for 20 hours or more, preferably 40 hours or more, to remove the moisture-containing gas. The alumina that has absorbed this moisture is
350℃ to 600℃, preferably 400℃ to 550℃
0.1 to 50 hours at a temperature of preferably 0.2 to 20
It is preferable to carry out the drying treatment under an atmosphere or circulation of a gas such as air or nitrogen for a period of time. This catalyst, in which water adsorption and dehydration are performed on Ziegler alumina, exhibits significantly improved activity in the isomerization reaction that imparts a branched structure to aliphatic olefins or increases the number of branched structures. The halogenated hydrocarbon containing fluorine and chlorine used in the present invention is an aliphatic hydrocarbon consisting of carbon, fluorine and chlorine, or carbon, hydrogen, fluorine and chlorine, and preferred examples thereof are as follows. Formula C _n H _o F _x Cl _y ... (where m is 1 to 2, n is 0 to 2, x is 1 to 5, y is 1 to 5, and m+1=
n+x+y/2). These compounds are halogenated hydrocarbons containing fluorine and chlorine, which usually belong to the class of substances called fluorocarbons. Examples of suitable fluorocarbons for use in the method of the invention are CHCl ₂ F ₂ , CClF ₃ , CHCl ₂ F,
_CCl3F , _CH2ClF , _CCl2F − _CCl2F , _CCl2F − _CCl2
and CF ₃ −CClF ₂ . Catalysts in which halogenation is carried out using halogenated hydrocarbons containing only either fluorine or chlorine are not sufficiently satisfactory in terms of activity, selectivity, or activity persistence for the isomerization reaction. No results are obtained. For example, a catalyst obtained by treating activated alumina with a fluorinated hydrocarbon containing only fluorine, such as methane tetrafluoride, methane trifluoride, or methane difluoride, as described in British Patent No. 1065005. or when activated alumina is subjected to water adsorption and partial dehydration treatment before being fluorinated with a fluorinated hydrocarbon containing only fluorine, as described in British Patent No. 1065009. It is clear that when a catalyst is used, there are more side reactions such as polymerization, disproportionation, hydrogen transfer, and decomposition than when using the catalyst of the present invention, and the activity duration is also short. Summer. Furthermore, although it is not clear what the reason is, according to the present invention, when treated with a halogenated hydrocarbon containing both fluorine and chlorine, the amount of fluorine is lower than when treated with a halogenated hydrocarbon containing only fluorine. It became clear that more elements were supported. The catalyst subjected to the halogenation treatment according to the present invention is characterized in that it contains both fluorine and chlorine as halogens. In the present invention, the halogenation treatment of the carrier is carried out in a gas phase using a halogenated hydrocarbon containing fluorine and chlorine as exemplified above. A suitable treatment method is to dilute and treat a stream of halogenated hydrocarbon containing fluorine and chlorine either alone or with an inert gas such as nitrogen or a non-reducing gas such as air. This method involves passing it over alumina. The main factors in the halogenation conditions are temperature and treatment time, which influence the amount of fluorine and chlorine supported. Furthermore, the amount of fluorine and chlorine supported is influenced by the type, amount, physical properties and shape of the alumina used, and the type and flow rate of the fluorine and chlorine containing hydrocarbons used, as well as the diluent. It is also affected by the type and amount. A suitable halogenation temperature for Ziegler alumina is 200 to 500°C, preferably 300 to 400°C. If the treatment temperature is lower than 200°C, the rate of halogenation of activated alumina will be slow and sufficient halogenation will not occur, resulting in insufficient activity improvement effect and also not being economical. If halogenation is carried out for a long time at a high temperature of over 500° C., inert substances such as crystalline aluminum fluoride are formed in the catalyst, and the effect of improving activity is insufficient. The halogenation treatment time is precisely determined depending on the required amount of fluorine and chlorine to be supported, but is usually between several minutes and several hours. When performing halogenation treatment using a halogenated hydrocarbon diluted with an inert gas such as nitrogen or a non-reducing gas such as air, the dilution ratio may be any value, but it should be 10 to 10% for the halogenated hydrocarbon.
1000 times is more practical. In this way, by diluting the halogenated hydrocarbon and using it, the halogenation treatment temperature can be adjusted. In addition, in order to make the reaction milder and to carry halogen more uniformly during halogenation treatment, moisture may coexist in the accompanying gas.
1000 molppm, preferably 10 to 500 molppm, is preferably allowed to coexist. Further, in order to more easily control the temperature of the halogenation treatment and to more uniformly support the halogen on the catalyst, it is preferable to carry out the halogenation treatment while the Ziegler alumina is in a fluidized state, but the halogenation treatment can also be carried out in a fixed bed. The pressure for halogenation treatment is not particularly limited, but it is desirable to avoid pressures that would cause the fluorine- and chlorine-containing hydrocarbons used to condense on the catalyst. It is more preferable that the When Ziegler alumina is treated with fluorine- and chlorine-containing hydrocarbons suitable for the present invention, the halogenation treatment conditions are more severe, i.e., high temperature, long time, and high concentration treatment agent conditions. Accordingly, the supported amounts of fluorine and chlorine both increase. In the present invention, the amount of halogen supported is fluorine.
When the amount of chlorine is less than 0.2wt% and the amount of chlorine is less than 0.2wt%, the amount of isobutene produced is almost the same as when using alumina alone, and the effect of halogenation is hardly recognized. Conversely, when the amount of halogen supported is more than 1.5 wt% of fluorine and 3.0 wt% of chlorine, side reactions occur preferentially, and products lighter or heavier than C ₄ hydrocarbons rapidly increase. The catalyst produced by the method of the present invention exhibits remarkable effects when used in isomerization reactions to obtain branched aliphatic olefins. Conventionally, activated alumina is fluorinated with hydrogen fluoride, fluorine gas, a fluorine-containing compound, etc., or chlorinated with hydrogen chloride, chlorine gas, chlorine-containing gas, etc. to produce a hydrocarbon conversion catalyst. well known. Furthermore, a method is also known in which activated alumina and a substance containing it are made to contain both fluorine and chlorine to form a catalyst. For example, in Japanese Patent Publication No. 40-1164, activated alumina is supported with alkali metals or alkaline earth metals, and then the double bonds of olefins are formed using a catalyst treated with halogenated hydrocarbons containing fluorine and chlorine. An isomerization method is shown. Furthermore, Japanese Patent Publication No. 39-11605 discloses a method for catalytic disproportionation and rearrangement of fluorine-containing alkanes, using a catalyst in which alumina is treated with a lower fluorinated hydrocarbon that may contain chlorine. Japanese Patent Publication No. 43-27748 discloses a method in which alumina is treated with a chlorine-containing compound and then a catalyst treated with a fluorine-containing compound is used in the same reaction. Additionally, U.S. Patent No. 3287439 (1966)
describes a method in which platinum-supported alumina is treated with chlorofluorocarbon and used for the isomerization of paraffins. Moreover, in Japanese Patent Publication No. 51-7655, crystalline alumina silicate is
Alternatively, an example is shown in which a catalyst treated with a chlorine-containing hydrocarbon is used in a toluene disproportionation reaction. However, these examples show that the catalyst obtained by treating activated alumina with a fluorine- and chlorine-containing hydrocarbon exhibits any activity in the isomerization reaction, which involves contact with aliphatic olefins and contains more branched structures. There is no mention of that at all. Furthermore, the method for preparing the special catalyst of the present invention is not disclosed. The linear aliphatic olefin to be isomerized by the catalyst of the present invention usually has 4 to 24 carbon atoms, preferably 4 to 24 carbon atoms.
The aliphatic olefin of No. 6 may be a single compound or a mixture of two or more thereof, and mixtures with other saturated hydrocarbons are also preferably used. More preferably, all or most of the acetylene or dienes in the raw material are removed by extraction or selective hydrogenation prior to this isomerization treatment, in view of the sustainability of the activity of the catalyst. The catalyst obtained in the present invention is most preferably used for isomerizing normal butene to isobutene, and is also suitable for isomerizing normal pentene to isopentene. In the isomerization reaction using the catalyst obtained according to the present invention, the aliphatic olefin alone or a hydrocarbon mixture containing the aliphatic olefin may be reacted as it is, but
It may be used in combination with a diluent gas such as nitrogen, carbon dioxide, helium or hydrogen. reaction is temperature
200℃ to 600℃, preferably 350℃ to 550℃
It will be held in It is also possible to gradually raise the temperature from low temperature during the reaction.
If the temperature is lower than 600℃, sufficient reaction will not occur.
When the temperature is higher than 0.degree. C., side reactions such as disproportionation, hydrogen migration and decomposition become significant. The pressure used is generally around atmospheric pressure, but any pressure may be used as long as it is sufficient to keep the reaction gas in the gas phase. The feed rate expressed in gas hourly space velocity (GHSV) is based on aliphatic olefins.
It is 100 to 10,000 V/V/hr, more preferably 300 to 3,000 V/V/hr. Furthermore, by allowing a small amount of water to coexist during the reaction, the selectivity of the isomerization reaction can be improved. In addition, in producing the catalyst by the method of the present invention and isomerizing olefin using the catalyst, the carrier or catalyst may be used in either a fixed bed or a fluidized bed, and the reaction may be carried out in the gas phase. is preferred. As explained above, the catalyst of the present invention exhibits significantly high activity in the isomerization reaction for obtaining branched aliphatic olefins from linear aliphatic olefins. Furthermore, the catalyst has good sustainability of activity, high stability of activity, and can be easily regenerated. It is also effective as a catalyst for easily and economically producing branched aliphatic olefins. Next, the present invention will be specifically explained with reference to Examples. Example 1 20 wt% of water was added to Pural SB (boehmite, α-AlOOH) powder obtained from Conclea, kneaded in a kneader, and then extruded to a diameter of 1.5 mm. After molding, it was air-dried for one day and night, and then dried for another day and night at 150°C. Place the dried material in an electric furnace and place it under air circulation.
Bake at 500℃ for 4 hours. After cooling, it was taken out and left in the air for two days and nights. The weight after standing was approximately 10wt% higher than that immediately after firing (this is referred to as alumina). Collect 11g of alumina (), fill it in a quartz reaction tube (10mmφ x 500mm), and heat it at 500℃.
After drying with a flow rate of 240/hr for 1.5 hours, the temperature was lowered to 330℃, and the nitrogen (240/hr) was dried with 200 ppm of moisture.
hr) and CCl ₂ F ₂ (Freon-12) gas.
The halogenation treatment was carried out by passing through a distance of 12.5 mm at a flow rate of 4.4 ml/min. Fluorine in the catalyst after treatment is 0.55wt
%, and chlorine was 1.0wt%. This catalyst is designated as A. An isomerization reaction of 1-butene was carried out using Catalyst A. 1-Butene with a purity of 98.1 vol% was used as a raw material and diluted with nitrogen to an equal volume. The reaction temperature is
The reaction was carried out at 400°C, GHSV (1-butene) of 1000, and normal pressure. At the outlet 2 hours after the start of the reaction, the composition is <C ₄ 14.8wt.
%, n-butane 5.8wt%, n-butene 31.7wt%,
i-butene was 32.4 wt%, and >C ₄ was 15.7 wt%. After a further 24 hours, <C ₄ 2.1wt%, n-butane
1.1wt%, n-butene 56.5wt%, i-butene
38.6 wt% and >1.7 wt% C ₄ , and Catalyst A showed excellent activity. Example 2 The alumina (2) prepared in Example 1 was fired again in an electric furnace at 500° C. for 4 hours under air circulation, and after cooling, it was taken out and left in the air for 2 days and nights (this is referred to as alumina (2)). The moisture content of this alumina () is approximately
It was 7wt%. This alumina () is crushed into 30 to 60 pieces,
Take about 35.2g of this and put it in a Pyrex fluidized bed halogenation equipment (35mmφ x 300mm), and
Nitrogen containing 200 ppm is flowed from the bottom at 240/hr to flow the alumina and raise the temperature to 340°C. Then, add gaseous Freon-12 at 6.3ml/min.
The catalyst was halogenated by entraining it with nitrogen at a rate of 350°C for 24 minutes. The fluorine of this catalyst is
0.56wt%, and chlorine was 1.08wt%. This catalyst is designated as B. Remove 10 ml from catalyst B without exposing it to air and fill it into the reaction tube described in Example 1. This reaction tube was used to perform an isomerization reaction of trans-2-butene. The purity of the raw material trans-2-butene is 99.2
It was %. This trans-2-butene was diluted with an equal amount of nitrogen, and the reaction was carried out at a reaction temperature of 400°C, GHSV (butene standard) 1000, and normal pressure. The reaction results are shown in Table 1.

[Table] Example 3 The catalyst used in Example 2 for 40 hours was calcined at 500° C. in nitrogen containing 5% oxygen until no carbon dioxide was produced at the outlet. After firing, lower the temperature to 350℃ and remove moisture.
The catalyst was reactivated by injecting 40 μl of carbon tetrachloride in several portions with a microsyringe under nitrogen flow containing 200 ppm. Thereafter, an activity test was conducted under the same reaction conditions as in Example 2. The results are shown in Table 2.

[Table] From the results, it was found that good activity could be obtained even if the regeneration operation was performed. Example 4 An activity test was conducted using Catalyst B of Example 2, using hydrogen instead of nitrogen in the reaction of Example 2, and keeping the other reaction conditions the same. Looking at the composition of the produced gas after 30 hours, <C ₄ s3.6, C ₄ s1.2, n-C' ₄ 56.3, i-
C′ ₄ was 35.6%, and C ₅ was 3.3% by weight, indicating that the activity using hydrogen was greater than when nitrogen was used.

Claims (1)

[Scope of Claims] 1 High purity product with a specific surface area of 150 m ² /g to 250 m ² /g, obtained by firing aluminum hydroxide produced as a by-product in the Ziegler method higher alcohol synthesis at 500°C to 750°C. It consists of activated alumina and fluorine and chlorine supported on the activated alumina, and the supported amount of fluorine and chlorine is 0.2 to 2.0 fluorine based on the weight of the total catalyst.
% and chlorine from 0.2 to 4.0%. 2. The catalyst composition according to claim 1, wherein each of the linear and branched aliphatic olefins has 4 to 5 carbon atoms. 3. The catalyst further contains one or more oxides selected from the group consisting of silica, titania, zirconia, magnesia, chromia, thoria, molybdena, tungsten oxide, and iron oxide. The catalyst composition according to item 1 or 2. 4 It is obtained by firing aluminum hydroxide, which is produced as a by-product in the Ziegler method higher alcohol synthesis, at 500°C to 750°C, and is immobilized intramolecularly on a high-purity activated alumina carrier with a specific surface area of 150 m ² /g to 250 m ² /g. Add one or more halogenated hydrocarbons containing fluorine and chlorine to 200
characterized by contact at a temperature of ~500°C,
0.2-2.0% fluorine and
A method for producing an isomerization catalyst for converting a linear aliphatic olefin into a branched aliphatic olefin, in which 0.2 to 4.0% of chlorine is supported on activated alumina. 5. The method according to claim 4, wherein each of the linear and branched aliphatic olefins has 4 to 5 carbon atoms. 6. A patent in which the carrier is made of activated alumina containing one or more oxides selected from the group consisting of silica, titania, zirconia, magnesia, chromia, thoria, molybdena, tungsten oxide, and iron oxide. The method according to claim 4 or 5. 7. Before contacting the carrier with the halogenated hydrocarbon, the carrier is brought into contact with a water-containing gas to adsorb moisture onto the carrier, and then the carrier that has absorbed the moisture is kept at a temperature of 350 to 600°C for 0.1 to 50 hours to dry. The method according to any one of claims 4-6. 8 Halogenated hydrocarbons containing fluorine and chlorine have the general formula CmHn Fx Cly [where m is 1 to 2, n is 0 to 2, x is 1 to 5, y is 1 to 5, and m+1=
n+x+y/2]
7. The method according to any one of items 7 to 7.