JPS5913734A - Preparation of tertiary olefin - Google Patents

Abstract

PURPOSE:To prepare a tertiary olefin, keeping the excellent catalytic activity for a long period, without losing the high long-term reactivity and selectivity even at a low temperature, by decomposing a tertiary ether in the presence of steam using a heteropolyacid supported on a neutral or acidic carrier as a catalyst. CONSTITUTION:A hetropolyacid of formula (X is center element such as P, Si, B, etc.; M is legand element such as Mo, W, V, etc.; l is >1; m is 0.1-10; n is 6-18; p is 10-70; q is 0-40), e.g. silicomolybdic acid, phosphotungstic acid, etc. is supported on a neutral or acidic carrier (e.g. silica, alumina, carbon black, etc.) in an amount of 1-70wt%, preferably 5-50wt% to obtain a catalyst. A tertiary ether is made to contact with the catalyst in the presence of steam at 80-350 deg.C, preferably 100-250 deg.C to obtain the objective compound. The amount of steam is preferably 0.5-5mol per 1mol of the raw material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing tertiary olefins by decomposition of tertiary ethers.

Methods are known for decomposing tertiary ethers into tertiary olefins and alcohols in the presence of various catalysts. For example, U.S. Pat. No. 3,170,000 proposes a method using various metal oxide catalysts, but the catalyst specifically disclosed herein has catalytic activity at low temperatures such as 200'C or less. Since the temperature is small, it has the disadvantage that it must be operated at high temperatures, which is undesirable from an industrial perspective.

Furthermore, according to Japanese Patent Publication No. 51-26401, a method using sulfates of copper, iron, nickel, aluminum, etc. as a catalyst has been proposed, but decomposition of sulfates under the reaction conditions leads to corrosion of the equipment and a decrease in activity. It is difficult to adopt it industrially because there are concerns that such troubles may occur. Sara G Kodada Japanese Patent Publication No. 47-41882 discloses a method in which alumina having a large specific surface area or alumina containing sulfate is used as a catalyst. However, since alumina with a large specific surface area easily etherifies the alcohol produced, water must be present during the reaction, but if water is present, a large amount of t-butanol will be produced as a by-product at low humidity below 200°C. It has the following drawbacks.

In addition, alumina catalysts containing sulfate have the disadvantage that crystallization of the sulfate is promoted in the presence of water vapor and the activity tends to decrease.

The present inventors investigated a method that can produce tertiary olefins with long-lasting activity, long-term reactivity, and high selectivity even at low temperatures, and as a result, they discovered a method using heteropolyacids. Ta. That is, the present invention
This is a method for producing a tertiary olefin, which comprises bringing a tertiary ether into contact with a heteropolyacid supported on a neutral or acidic carrier G in the presence of water vapor.

The tertiary ether which is a raw material of the present invention is a -valent or polyvalent ether, and at least one of the hydrocarbon groups bonded to etheric oxygen is a tertiary hydrocarbon group. Specifically, primary and tertiary butyl ether such as methyl tert-butyl ether, ethyl tert-butyl ether, methyl tert-amyl ether, ethyl tert-amyl needle, methyl tert-hexyl ether, methyl tert-heptyl ether, and ethylene glycol di-tert-butyl ether are used. Tertiary ether can be cited as a representative example. Although these can be easily obtained by the reaction of tertiary olefins and primary alcohols, tertiary olefins can be selectively etherified by the reaction of olefin mixtures containing tertiary olefins with primary alcohols. By applying the present invention after separation, a highly purified tertiary olefin can be isolated from an olefin mixture containing a tertiary olefin.

In the present invention, a heteropolyacid supported on a neutral or acidic carrier is used as a catalyst. Examples of the carrier include silica, alumina, silica-alumina, carbon black, titania, silica-titania, and zirconia.

When a basic carrier is used instead of these carriers, the catalytic activity is low and this is not preferred.

The heteropolyacid supported on the carrier has the general formula H1XmMn
op-q, H2O (where X is the central element,
For example, it represents P% Sis Bz Tis Ges As, and M represents a coordination element, such as Mo.
,W.

V, etc., 4 is a number larger than 1, m is 0.1
from 10 to 10, n from 6 to 18, P from 1o to 70,
q is 0 to 4o). More specifically, representative examples include silicomolybdic acid, phosphomolybdic acid, boromolybdic acid, silicotungstic acid, phosphotungstic acid, and borotungstic acid.

These heteropolyacids are prepared by heating 1 to 70 times the carrier G,
In particular, it is desirable that 5 to 50% by weight be supported.

The decomposition reaction is carried out in the presence of water vapor under conditions in which the raw material ether is in a gas phase. The preferred reaction temperature is 80 to 3
50°C, especially in the range of ioo to 250°C.

The amount of water vapor present is sufficient in the range of 0.1 to 20 mol, particularly 0.5 to 5 mol, per mol of raw material. Although the coexistence of water vapor is important for preventing a decrease in the activity of the catalyst, it is not necessarily necessary to use it continuously, and it may be used intermittently.

For example, the decomposition reaction is carried out in a catalyst packed bed adjusted to a predetermined temperature.
This can be carried out by circulating a mixed gas containing raw material ether and water vapor.

At this time, it is not necessary to use a particular diluent, but if desired, an inert diluent such as nitrogen may be used. The amount of tertiary ether fed per hour relative to the catalyst volume (LH3
V ) is suitably in the range of 0.1 to 50, particularly 065 to 15.

According to the present invention, the catalytic activity is high at relatively low temperatures, and side reactions such as etherification of the alcohol produced with carbon dioxide hardly occur, so that the desired tertiary olefin can be produced with good yield.

This will be explained in more detail with reference to Examples below.

Example 1 An aqueous solution prepared by adding 22 g of water to 5.9 g of phosphomolybdic acid aqueous solution (manufactured by Nippon Inorganic Chemical Industry Co., Ltd., brand name NPM-40) was classified into 32-6 o mesh using silica gel (Model Gel 5D manufactured by Fuji Depison). (10 g) was impregnated. - After being left overnight, it was dried at 70-80'C for one day and night.

Then, it was fired for 3 hours at 250'C in an air atmosphere. IQml of this catalyst was filled into a stainless steel reactor with an inner diameter of 17 mm, and the temperature was adjusted from the outside to the temperature shown in Table 1 using a small electric furnace. Raw materials methyl t-butyl ether (M to E) and water were each 3QJ/H.

It was supplied to the reactor via a preheater by a metering pump at 6.8 mβ/H. The pressure was normal.

The generated gas exiting the catalyst bed was collected by condensation and liquefaction through a trap cooled with ice water and a trap cooled with dry ice.

The collected liquid was analyzed by gas chromatography to determine the contents of inbutylene, methanol, and unreacted MTBE.

The results are shown in Table 1.

The definitions of reaction rate and selectivity in Table 1 are as follows.

MTBE reaction rate (%) Moles of MTEE supplied per hour Isobutylene selectivity (%) Moles of inbutylene produced per hour Bxi□.

Number of moles of reacted MTBE per hour Methanol selectivity (%) Number of moles of MTBEO reacted per hour Number of moles of MTBE fed per hour Number of moles of recovered unreacted MTBE per hour Examples 2 to 4 Instead of the phosphomolybdic acid aqueous solution in step 1, use a tungstic acid aqueous solution (manufactured by Japan Inorganic Chemical Industry Co., Ltd., brand name: NPW).
40), silicomolybdic acid aqueous solution (manufactured by Nippon Inorganic Chemical Industry Co., Ltd., brand name Ivsr, +-40), and silicotungstic acid aqueous solution (manufactured by Nippon Inorganic Chemical Industry Co., Ltd., brand name N5W-40) were used, 6 g each, and crushed into 32 to 6 o meshes. Classified titania (manufactured by Diamond Catalyst, brand name DC-3144) 1
A catalyst supported on 0g was prepared in the same manner, and M T B
A decomposition test of E was conducted under the same conditions and method as in Example 1. The results are shown in Table 1.

Example 5 Methyl t-amyl ether (MTA
MTAE was decomposed using the same catalyst and method as in Example 1, except that B) was used. The reaction rate of MTAE was 98%,
The selectivity for 2-methylbutene-2 and 2-methylbutene-1 was 98%, and the selectivity for methanol was 99%.

Example 6 10 m4 of the catalyst prepared in Example 1 was filled into a stainless steel tube with an inner diameter of 4 mm. A preheating tube was attached to the upstream side of this reaction tube and placed in a silicone oil bath, and the temperature of the oil bath was controlled to set the reaction temperature. A pressure regulator was attached to the downstream side of the reaction tube. The generated gas that passed through the pressure regulator was collected and analyzed in the same manner as in Example 1.

Raw material MTBE and water are each 3Qml/H, 6.8ml
/H with a metering pump. Reaction temperature is 200°C1
The reaction was carried out at a pressure of 5 kg/an2a. Reaction start 1
The reaction rate of MTBK after our was 97%, the selectivity of inbutylene was 99%, and the selectivity of methanol was 98%. 2
After 00 hours of continuous testing, the reaction rate of MTBE is 96%, the selectivity of inbutylene is 99%, and the selectivity of methanol is 98%.
, and almost no deterioration in activity was observed during this period.

Comparative Example 1 M was prepared in the same manner as in Example 6 except that water was not supplied.
A TBE decomposition test was conducted. After 10 hours of reaction start, M
TBE reaction rate is 96%, inbutylene selectivity is 98%
Although the methanol selectivity was 97%, the MTBE reaction rate decreased to 81% after 200 hours.

Comparative example 2 NiSO4・s H70 (manufactured by Wako Pure Chemical Industries, special grade) 0.8
Dissolve g in 18 g of water and add silica gel (Fuji Depison ID type gel classified into 32 to 60 mesh) 9
It was absorbed into g. After drying for 24 hours at 70-80°C, 3
It was baked at 00°C for 3 hours. A test was conducted in the same manner as in Example 6 using 10 m4 of this catalyst.

Feed raw material MTBE at 30 mβ/H, reaction temperature 2
Decomposition was carried out at 00'C and reaction pressure of 5 kq/c Nor+2G.

10 hours after the start of the reaction, the reaction rate of MTBE was 96%, the selectivity of inbutylene was 99%, and the selectivity of methanol was 99%, but after 200 hours, the reaction rate of MTEE was 86%.
It declined to .

Comparative Example 3 Titania used as a carrier in Examples 2 to 4 was used as a catalyst without supporting a heteropolyacid, and M
We conducted a disassembly test of TE E.

MTBE reaction rate is 25%, isobutylene selectivity is 10
0% methanol selectivity was 100%.

Comparative Example 4 MTBE was decomposed in exactly the same manner as in Example 6, except that r-alumina (N611-N, manufactured by 8 Koku Kagaku Co., Ltd., specific surface area 210 m/g) crushed and classified into 62 to 60 meshes was used.

The reaction rate of MTBE after 10 hours of reaction initiation was 65%, the selectivity of isobutylene was 90%, and the selectivity of methanol was 99%, but after a continuous test of 200 hours, the reaction rate was 49%.
It declined to . The reason for the low selectivity of isobutylene was that there was a large amount of t-butanol as a by-product.

Applicant: Mitsui Petrochemical Industries, Ltd. Agent Kazu Yamaguchi

Claims (1)

[Claims] (1) A method for producing a tertiary olefin, which comprises bringing a tertiary ether into contact with a heteropolyacid supported on a neutral or acidic carrier in the presence of water vapor.