JPH11158102A - Production of dibutyl ether - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an industrially suitable simple process for the production of dibutyl ether useful as an oxygen-containing fuel base in high efficiency by dehydrative etherification reaction of n-butyl alcohol. SOLUTION: A solid superstrong acid catalyst having an acid strength corresponding to the Hammett acidity function (Ho) of Ho<-11.9 is used as a catalyst for the subject process. The solid superstrong acid catalyst satisfying the formula can be produced by supporting a sulfate radical precursor on the hydroxide or oxide of a metal of the group III, IV or VIII of the periodic table and baking the product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing dibutyl ether, and provides a simple and efficient method for producing dibutyl ether from n-butyl alcohol by a dehydration reaction.

[0002]

2. Description of the Related Art In addition to use as a solvent, dibutyl ether is also used as a base material for gas oil fuel, and has effects such as improvement of cetane number and improvement of low-temperature characteristics (clouding point and clogging point). In view of these characteristics, dibutyl ether is generally useful as an oxygen-containing fuel base material, and the demand for oxygen-containing fuel base material is expected to increase in the future, so that the demand for dibutyl ether will further increase. Is expected.

[0003] As a method for synthesizing dibutyl ether, several methods have hitherto been known. Many are n
-A method for dehydrating butanol, wherein a reaction in the liquid phase is carried out using a zeolite catalyst such as Y-type zeolite as a catalyst for the dehydration reaction (Japanese Patent Laid-Open No.
No. 7432), a method using phosphotungstic acid as a catalyst (Japanese Patent Application Laid-Open No. 5-25076), a method using a layered clay (Japanese Patent Application Laid-Open No. 60-215642), and a method using bentonite (EP-A0031).
252).

[0004] However, all of the known methods for producing dibutyl ether are unsatisfactory for industrial practice. That is, the synthesis method using a zeolite catalyst has a drawback that not only the yield of dibutyl ether is low but also the acid strength of the catalyst is low, so that the reaction must be performed at a high temperature. As a result, sec-butyl alcohol, n-butyl-sec-butyl ether, n-butyl-t
ert-butyl ether, cis-2-butene, trans-2-
Many types of by-products are formed, such as butene and iso-butene. The method using phosphotungstic acid as a catalyst,
Since the phosphotungstic acid easily dissolves in water produced as a by-product, it is necessary to remove and recover the catalyst from the reaction and recovery solution, and the separation and purification steps including this operation become complicated.
In addition, since the recovered liquid is corrosive, there is a problem that expensive materials must be used for the material constituting the reactor.

In the synthesis method using a layered clay catalyst, not only the conversion of n-butyl alcohol and the yield of dibutyl ether are low, but also the acid strength of the catalyst is low as in the case of the zeolite catalyst. And there is a common problem in that by-products are formed as a result. Also, in order to increase the yield of dibutyl ether, the LHSV (liquid hourly space velocity) of the reactor must be reduced.

In the synthesis method using a bentonite catalyst, a relatively high conversion of n-butyl alcohol and a dibutyl ether yield can be obtained. However, since the acid strength of the catalyst is low as in the case of the zeolite catalyst, the reaction must be performed at a high temperature. Not
In this case, too, there is a disadvantage that various types of by-products are generated.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to take the above-mentioned state of the art one step further and produce dibutyl ether useful as an oxygen-containing fuel base material more efficiently than in the past by a simple one-step method. It is to provide a method that can do this.

[0008]

The method for producing dibutyl ether of the present invention is a method for producing dibutyl ether by etherifying n-butyl alcohol by a dehydration reaction, wherein the catalyst has a Hammett function (Ho) of Ho.
It is characterized by using a solid superacid catalyst having an acid strength of <-11.9.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The n-butyl alcohol used as a raw material preferably does not contain an acidic substance causing corrosion of a reactor or a basic substance becoming a catalyst poison. n
As for -butyl alcohol, in addition to pure n-butyl alcohol, a mixture of n-butyl alcohol can be used. The n-butyl alcohol mixture refers to a mixture containing n-butyl alcohol as a main component, isobutyl alcohol, and a hydrocarbon having 2 to 5 carbon atoms. n
The concentration of n-butyl alcohol in the -butyl alcohol mixture is preferably at least 80 mol%, particularly preferably at least 95 mol%.

[0010] Even if water is contained in n-butyl alcohol, it is not impossible to use it. However, if water is present, it coordinates with the catalyst and lowers the activity. Low is desirable. In this case, the concentration of n-butyl alcohol is preferably at least 95 mol%, particularly preferably at least 99 mol%.

As the n-butyl alcohol and the n-butyl alcohol mixture, those produced in processes such as the Reppe method, the oxo method and the acetaldehyde method can be used, and the production method is not limited.

The solid superacid catalyst used as a catalyst in the present invention has a Hammett function (Ho) of Ho <Ho as described above.
It has an acid strength of -11.9. To obtain such a solid superacid catalyst, a sulfate precursor is supported on a hydroxide or oxide of a metal of Group III, preferably Group IIIB, Group IV or Group VIII of the Periodic Table. And sinter it. Here, the periodic table of the elements was based on the one described in the spread on the back of the cover of "Chemical Dictionary" (1987) by Morikita Publishing.

[0013] The metal forming the oxide or hydroxide serving as a carrier may be aluminum, gallium, indium and thallium in Group IIIB, titanium, zirconium, silicon, tin, hafnium and germanium in Group IV, or Group VIII. Preferred metals of the iron group include iron, cobalt, and nickel, of which aluminum, titanium, zirconium, silicon, tin and iron are particularly preferred. One or more oxides, hydroxides, composite oxides or composite hydroxides of these metals can be used. It is particularly preferable to use a composite hydroxide. Specific examples of the carrier include alumina (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), zirconia-alumina (ZrO ₂ .Al ₂ O ₃ ),
Zirconia ferric oxide _{(ZrO 2 · Fe 2 O 3} ), zirconia (II) oxide gallium _{(ZrO 2 · Ga 2 O 3} ), zirconia-titania (ZrO ₂ · TiO _2), zirconia oxide of cobalt ( ZrO ₂ .CoO) and the like.

As the sulfate precursor, sulfuric acid, ammonium sulfate, ammonium hydrogen sulfate, sulfuryl chloride and the like can be used. Particularly preferred are sulfuric acid, ammonium sulfate and sulfuryl chloride.

If an example of a method for producing a solid superacid catalyst is shown, the concentration is 0.01 to 10 mol / L, preferably 0.1 to 10 mol / L.
Prepare a solution of 5 mol / L sulfate precursor, and immerse the carrier, that is, the oxide or hydroxide in the solution, or
Alternatively, the solution is passed through or impregnated in a carrier to obtain a solution containing 1 to 10 parts by weight of a solution of a sulfate group precursor with respect to 1 part by weight of the carrier. Is a step of firing at 450 to 700 ° C. for about 0.5 to 30 hours. It is of course possible to follow other methods for producing a solid superacid catalyst, and there is no particular limitation on the method for producing the catalyst used in the present invention.

The solid superacid catalyst used in the present invention comprises:
Preferably, the surface area is in the range from 50 to ²⁰⁰ m2 / g. The acid strength requires that the Hammett function (H ₀ ) satisfy H ₀ <−11.9 as described above, and particularly, H ₀ ≦ −1.
It is preferably 2.9. The Hammett function representing the acid strength has been introduced in many books, but here, in particular, is based on "New Experimental Chemistry Course, Vol. 16, Reaction and Rate", Maruzen Co., Ltd., pp. 210-226. The Hammett function can be measured using a Hammett indicator, a nitroaniline-based indicator, a nitrobenzene-based indicator, or the like.
Specific indicators are shown on page 214 of the same book.

According to the method of the present invention, n-butyl alcohol is dehydrated in the presence of a specific solid superacid catalyst,
In producing dibutyl ether, the reaction system is not particularly limited, and a fixed bed flow system, a fluidized bed system, a moving bed system, a batch system, or any other system can be employed.

In the case of carrying out with a fixed bed flow system, a carrier gas can be used.
An inert gas such as nitrogen, or hydrogen, carbon dioxide, methane, or the like can be used.

The reaction temperature is 50-400 ° C., preferably 7
The temperature is selected from the range of 0 to 300 ° C, more preferably 80 to 250 ° C. If the reaction temperature is low, the amount of raw materials remaining unreacted increases, and the recycling cost increases. When the reaction temperature is high, the selectivity to by-products is increased, and not only the production of dibutyl ether is suppressed, but also the deactivation of the catalyst is caused by elimination of sulfate groups.

The reaction pressure is atmospheric pressure to 100 kg / cm ^2, preferably atmospheric pressure to 50 kg / cm ^2, more preferably atmospheric pressure ~20k
Select from the range of g / cm ² . If the reaction pressure is low, the reactivity of the ether is low due to the gas-liquid reaction. On the other hand, if the reaction pressure is to be increased, the pressure resistance of the reactor must be increased, and expensive materials must be used.

In the case of the fixed bed flow type, the feed rate (L
HSV [/ hr]) is 0.01 to 30, preferably 0.1 to 30.
To 20, more preferably 0.1 to 10.
If the LHSV is too small, the amount of the raw material supplied is small relative to the amount of the catalyst, so that the operating cost increases. LH
If the SV is too large, the amount of the raw material that passes through the catalyst bed without reacting increases, so that the recycling cost increases.

In the case of the batch type, the amount of the catalyst to be used can be varied in a wide range, but generally speaking, 0.01 to 20 parts by weight, preferably 0.05 to 20 parts by weight, per 1 part by weight of the raw material. 10 parts by weight, more preferably 0.1 to 5 parts by weight. The reaction time is 1 minute to 48 hours,
Preferably it is 10 minutes to 24 hours, more preferably 1 hour to 12 hours.

After completion of the reaction, various methods can be used to recover the produced dibutyl ether, and there is no particular limitation. An appropriate method may be employed depending on the purity and properties desired for the target substance, the purpose of use, and the like. A preferred example is a method in which the reaction-recovered component flowing out of the reaction tower is blended with a light oil fraction in an extraction tower, and the obtained oil layer is recovered as a high cetane number light oil.

[0024]

According to the present invention, the method for producing dibutyl ether from n-butyl alcohol can be simplified by using a solid superacid catalyst having a Hammett function (H ₀ ) of H ₀ <−11.9. Thus, dibutyl ether can be efficiently produced at a low cost and at a low cost. The solid superacid catalyst can be easily produced by carrying a sulfate group precursor on an oxide or hydroxide of a metal belonging to Group III, IV or VIII of the periodic table and calcining it. Therefore, the method of the present invention is suitable as an industrial production method of dibutyl ether, which is useful as an oxygen-containing fuel base material.

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, which are for illustrative purposes only and do not limit the present invention.

[Catalyst Production Example 1] Zirconium hydroxide was precipitated by dissolving 2000 g of zirconium oxychloride in pure water and gradually adding aqueous ammonia until the pH reached 10 with stirring. The resulting zirconium hydroxide was separated, impregnated with 7 L of sulfuric acid at a concentration of 0.5 mol at a time, then filtered, dried and calcined at 600 ° C. for 3 hours to prepare a catalyst.

The acid strength (Hammet function H ₀ ) of this catalyst was determined by using anthraquinone (discoloration point: H ₀ = −8.2) and p-nitrotoluene (discoloration point in the ultraviolet region: H ₀ = -10.5).
And p-nitrochlorobenzene (discoloration point: H ₀ = −1
As a result of measurement using 2.7), all the indicators showed an acidic color or a maximum absorption wavelength (ultraviolet region) on the acidic side. Therefore, the acid strength of this catalyst was H ₀ ≦ −12.7 when expressed by the Hammett function (H ₀ ).

Example 1 Using the catalyst produced in Catalyst Production Example 1, dibutyl ether was produced under the following conditions using a 200 ml autoclave as a reaction vessel. Starting material n-butyl alcohol: 37.0 ml Catalyst: 2.4 ml Reaction temperature: 190 ° C. Reaction pressure: 9 kg / cm ² The reaction mixture 2 hours after the start of the reaction was recovered and analyzed by GC (gas chromatography). However, the following results were obtained. Conversion of n-butyl alcohol: 18.1 mol% Selectivity of dibutyl ether to by-products: 94.
9%.

Example 2 Dibutyl ether was produced under the following conditions using the catalyst produced in Catalyst Production Example 1 and using a 200 ml autoclave as a reaction vessel. Starting material n-butyl alcohol: 37.0 ml Catalyst: 2.4 ml Reaction temperature: 190 ° C. Reaction pressure: 12 kg / cm ² The reaction mixture 5 hours after the start of the reaction was recovered and analyzed by GC (gas chromatography). However, the following results were obtained. Conversion of n-butyl alcohol: 25.7 mol% Selectivity of dibutyl ether to by-products: 94.
5%.

[Example 3] Using the catalyst produced in the same manner as in Catalyst Production Example 1, and using a 200 ml autoclave as a reaction vessel under the following conditions, that is, by increasing the reaction temperature and reaction pressure as compared with Example 1, Production of butyl ether was performed. Starting material n-butyl alcohol: 37.0 ml Catalyst: 2.4 ml Reaction temperature: 220 ° C. Reaction pressure: 27 kg / cm ² The reaction mixture 2 hours after the start of the reaction was recovered and analyzed by GC (gas chromatography). However, the following results were obtained. Conversion of n-butyl alcohol: 48.9 mol% Selectivity of dibutyl ether to by-products: 96.
1%.

[Catalyst Production Example 2] A mixture of zirconium hydroxide and aluminum hydroxide was prepared by dissolving 2,000 g of zirconium oxychloride and 290 g of aluminum nitrate in pure water, and gradually dropping ammonia water to pH 10 with stirring. The hydroxide was deposited. The obtained composite hydroxide was separated, and impregnated with 7 L of sulfuric acid at a concentration of 0.5 mol at a time as in the case of Catalyst Production Example 1.
Dried. The dried product was calcined at 700 ° C. for 3 hours to prepare a catalyst.

When the acid strength of this catalyst was measured by the same test method as that used in Catalyst Production Example 1, the acid strength expressed by the Hammett function (H ₀ ) was H ₀ ≦ −12.7.
Was confirmed.

Example 4 Using the catalyst produced in Catalyst Production Example 2, dibutyl ether was produced under the following conditions using a 200 ml autoclave as a reaction vessel. Starting material n-butyl alcohol: 37.0 ml Catalyst: 2.4 ml Reaction temperature: 220 ° C. Reaction pressure: 31 kg / cm ² The reaction mixture 2 hours after the start of the reaction was recovered and analyzed by GC (gas chromatography). However, the following results were obtained. Conversion of n-butyl alcohol: 68.1 mol% Selectivity of dibutyl ether to by-products: 99.
2%.

Comparative Example 1 Dibutyl ether was produced at a reaction temperature of 190 ° C. using a rare earth metal-exchanged Y faujasite (manufactured by Union Carbide, trade name: SK500) as a catalyst. The reaction mixture 2 hours after the start of the reaction was recovered and analyzed by GC (gas chromatography). The results were as follows. Conversion of n-butyl alcohol: 15.5 mol% Selectivity of dibutyl ether to by-products: 81.
0%.

Comparative Example 2 Dibutyl ether was produced at a reaction temperature of 220 ° C. using a titania-exchanged layered clay catalyst as a catalyst. The reaction mixture 2 hours after the start of the reaction was recovered and analyzed by GC (gas chromatography). The results were as follows. Conversion of n-butyl alcohol: 38.0 mol% Selectivity of dibutyl ether to by-products: 83.
1%.

Comparative Example 3 The catalyst was ZSM-5 (Si / Al
= 40), and dibutyl ether was produced under the following conditions. Starting material n-butyl alcohol: 37.0 ml Catalyst: 2.4 ml Reaction temperature: 190 ° C. Reaction pressure: 8 kg / cm 2 The reaction mixture 2 hours after the start of the reaction was recovered and analyzed by GC (gas chromatography). The following results were obtained. Conversion of n-butyl alcohol: 0.3 mol% Selectivity of dibutyl ether to by-products: 50.
0%.

Claims (3)

[Claims] 1. A method for producing dibutyl ether by etherifying n-butyl alcohol by a dehydration reaction, wherein the catalyst has a Hammett function (Ho) of Ho <
A method for producing dibutyl ether, comprising using a solid superacid catalyst having an acid strength of -11.9. 2. As a solid superacid catalyst, Periodic Table III
2. The dibutyl ether according to claim 1, which is obtained by supporting a sulfate group precursor on a hydroxide or oxide of a Group IV, IV or VIII metal and sintering it.
Tell manufacturing method. 3. An n-butyl alcohol having a purity of 80% or more is used as a reaction raw material.
Or the method for producing dibutyl ether according to 2.