JPS5833851B2 - diacetoxybutene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for producing diacetoxybutene by catalytically reacting butadiene, acetic acid, and oxygen or an oxygen-containing gas in the presence of a palladium-based catalyst.

It is known to produce diacetoxybutene by reacting butadiene, acetic acid, and oxygen in the presence of a palladium-based catalyst, and various methods have been proposed.

However, when the reaction is carried out over a long period of time in such a method, the activity of the catalyst suddenly decreases, and it is often impossible to maintain an industrially satisfactory reaction rate for a long period of time.

As a result of various studies on the causes of the decrease in the activity of the reaction catalyst, the present inventor found that butadiene used in the reaction and the products polymerize in the reaction system and adhere to the catalyst surface, covering the catalyst with an inert film. It was found that the catalyst activity decreased.

Therefore, as a result of intensive research into methods for preventing the polymerization of butadiene and the reaction product in this reaction system, it was discovered that elemental sulfur does not have a negative effect on the catalyst itself, and that it has a remarkable effect on preventing such polymerization. The present invention was achieved based on this knowledge.

The present invention aims to provide an industrially advantageous method for producing diacetoxybutene from butadiene, acetic acid, and oxygen, and the gist of the present invention is as follows.

(1) A method for producing diacetoxybutene, which comprises catalytically reacting butadiene, acetic acid, and oxygen or an oxygen-containing gas in the presence of a supported palladium-based catalyst and elemental sulfur. (2) Butadiene, acetic acid, and oxygen or an oxygen-containing gas. in the presence of a supported palladium-based catalyst and elemental sulfur to produce diacetoxybutene, the reaction products may be butadiene, acetic acid, and the produced diacetoxybutene are separated by distillation, and at least the resulting distillation residue is A method for producing diacetoxybutene, characterized in that a portion thereof is supplied to an acetoxylation reaction zone.The present invention will now be described in detail.

The supported palladium catalyst used in this reaction is:
A catalyst in which palladium metal alone or palladium metal and at least one promoter metal selected from bismuth, selenium, antimony, and hysterol is supported on a carrier is suitable.

Any catalyst carrier can be selected, and specific examples include activated carbon, silica gel, silica alumina, alumina, clay, bauxite, magnesia, diatomaceous earth, and pumice.

The amount of catalyst metal supported in the catalyst is usually 0 for palladium metal.
．． 1-20% (by weight), other promoter metals 0.01-3
It is selected within the range of 0 (weight)%.

In addition, instead of supporting the co-catalyst component on a carrier, a compound such as an antimony compound, a selenium compound, a tellurium compound, a bismuth compound, etc. may be included in the reaction solution (and further,
If necessary, halogen ions can be allowed to coexist in the reaction solution during the reaction.

The reaction is carried out at 50°C to 160°C, preferably 80°C to 12°C.
Performed at 0°C.

The reaction pressure is determined by taking into consideration the required oxygen partial pressure and the explosive composition of butadiene and oxygen, and is higher than normal pressure, usually 5 to 3001 cg/ciG, preferably 40 to 120 cg/ciG.
Selected in the range of kg/ctAG.

Although the reaction method can be carried out in either a fixed bed or a suspended bed, the fixed bed method is industrially advantageous.

The reaction raw materials are not particularly limited as long as a gas such as an oxygen-containing gas and a liquid raw material such as acetic acid or phtadiene can be brought into sufficient contact with the catalyst in a gas-liquid co-current or gas-liquid counter-current system. It is advantageous to allow the liquid feedstock to descend downwards and the gaseous feedstock to pass downwards in a fixed bed.

The ratio of acetic acid and butadiene as reaction raw materials can be arbitrarily determined, but usually 1 to 10 parts by weight, preferably 4 to 6 parts by weight, of acetic acid is used per 1 part by weight of butadiene.

The oxygen-containing gas is 5 to 20 mol per mol of acetic acid supplied,
Preferably 8 to 15 moles are supplied.

The reactor is not particularly limited as long as the reaction heat can be easily controlled, such as a multi-tubular external cooling type or an adiabatic multi-stage intercooled type, and the material of the reactor is 5US316 to 5US3.
Ni, Cr SM than 16.

Steel with a high content of is desirable.

According to the method of the invention, the acetoxylation reaction must be carried out in the presence of elemental sulfur, which makes it possible to significantly prevent a decrease in the activity of the catalyst, and this effect is particularly noticeable at high reaction temperatures.

Figure 1 shows the relationship between the amount of elemental sulfur added to the reaction system and the deactivation rate of the catalyst (the time required for the initial activity to reach 172). Acetic acid 40? / hr Butadiene 15'? /h
r and a mixed gas of nitrogen and oxygen at 160 Nl/hr under the conditions of a pressure of 40 kg/caG, a temperature of 100°C, and an oxygen concentration of 3%, at which time various amounts of elemental sulfur were subjected to the reaction with respect to butadiene, This is the result of investigating the effect on the catalyst.

The catalyst is activated carbon with 4 to 6 meshes (surface area 850 mF/f
) with pd (2wt%) and Te (Te/ pd=0.3
0: atomic ratio) was used.

As is clear from this result, if the amount of elemental sulfur is too small, there is no effect, and if it is too large, it may have an adverse effect.

Therefore, usually o, ooooi~ for 1 part by weight of butadiene.
It is applied in a range of 0.007 parts by weight, but the most effective range is 0.0002 to 0.002 parts by weight, and the catalyst life is actually more than doubled.

FIG. 2 shows the relationship between the reaction temperature and the catalyst deactivation rate (the time required for the initial activity to be reduced to 1/2) when 1000 wt of elemental sulfur was added and 99 m2 was added.

The reaction conditions were the same as in FIG. 1 except that the reaction temperature was varied.

Below 80°C, the polymerization rate of butadiene and the reaction product is not large enough to affect the catalyst activity;
Butylcatechol (TBC) maintains its polymerization prevention effect.

However, when the temperature exceeds 80° C., the polymerization rate itself increases, and TBC no longer maintains its polymerization prevention function, so that the catalyst activity rapidly decreases.

However, as is clear from FIG. 2, if elemental sulfur is present in accordance with the method of the present invention, the decrease in catalytic activity can be extremely effectively suppressed at higher temperatures of 80° C. or higher.

Elemental sulfur can be used in liquid butadiene, acetic acid or
There are no particular restrictions on the method, as long as mabutadiene and acetic acid are pre-dissolved in a mixture and then fed to the reactor; however, acetic acid with a higher concentration of elemental sulfur dissolved therein can be pumped into the reaction zone in the required amount. It is better to supply

In this case, it is preferable to supply not only to the reaction zone but also at a stage before the butadiene in a solution state is exposed to a temperature of 80° C. or higher, that is, at a stage before the butadiene is introduced into the preheater.

Note that preheating of butadiene may be performed only with butadiene, but it is advantageous to preheat it in a mixed state with acetic acid and further with a raw material oxygen-containing gas.

The elemental sulfur added to the reaction system does not necessarily have to be new, and similar effects can be obtained by recycling the reaction solution containing elemental sulfur.

However, although direct recycling of the reaction solution achieves the effect of preventing the formation of polymers, on the other hand, the desired product is also simultaneously supplied to the reactor, resulting in the disadvantage that the reaction rate is suppressed by the product.

As a result of studying the effective use of elemental sulfur supplied to the reaction system, the present inventor found that the acetoxylation reaction is not inhibited even if the residue obtained by distilling the desired diacetoxybutene from the reaction product is supplied to the reaction system as it is. Moreover, it was found that the effect of suppressing the polymerization reaction by elemental sulfur can be sufficiently achieved.

Based on this knowledge, in the method of the present invention, diacetoxybutene is separated by distillation from the acetoxylation reaction product containing elemental sulfur, and at least a part of the obtained residue is used as an elemental sulfur source in the reaction system. circulates.

There are various methods to do this, but first, butadiene is separated from the reaction product, then unreacted acetic acid is separated by distillation, and finally the product diacetoxybutene is separated by distillation, and the remainder is recycled. It is also preferable.

According to FIG. 3, an example of the recycling method according to the present invention is shown.

Elemental sulfur is supplied from ■ and acetic acid is supplied from ■ to the dissolution tank ■ and dissolved, oxygen or oxygen-containing gas is supplied from ■, butadiene is supplied from ■, and acetic acid is heated from ■ together with sulfur supplied from the dissolution tank in a preheater ■. The mixture is heated to a temperature of 1, and introduced into two acetoxylation reaction towers.

The reactants are separated into gas and liquid in the gas-liquid separation tower ■, and the gas is cooled.
After compression, part of it is recycled to the reaction system and part of it is discharged.

The liquid is introduced into the butadiene recovery tower (■) from (■).

Butadiene is distilled and recovered from (2), and the bottom liquid is introduced from (2) into the acetic acid recovery column (4).

Remove the fraction containing acetic acid as the main component from the [phase], and the bottom liquid is introduced into the diacetoxybutene separation column ①.

Diacetoxybutene is recovered from the @, and the residue taken out from the bottom of the column is introduced from the [phase] into the dissolution tank ① and is again supplied to the reaction system.

The proportion of residue recycled to the reaction system cannot be uniformly determined because it varies depending on the reaction conditions, concentration conditions during distillation, and the amount of newly added elemental sulfur, but it is usually recycled to the bottom of the diacetoxybutene separation column. 5-80% of the residue, preferably 10-50%.

As described above, when diacetoxybutene is produced by catalytically reacting butadiene, acetic acid, and oxygen in the presence of a supported palladium-based catalyst according to the method of the present invention, the presence of elemental sulfur prevents the polymerization of butadiene and the reaction product. It is possible to inhibit the catalyst activity from decreasing, extend the life of the catalyst, and stably carry out the acetoxylation reaction over a long period of time.

In addition, diacetoxybutene can be economically advantageously obtained by recycling the distillation residue after distillation separation of the produced diacetoxybutene as a source of elemental sulfur according to the method of the present invention.

Next, the method of the present invention will be specifically explained using examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Note that the present invention is not limited to the following examples.

In addition, ppm in the following examples indicates a weight unit.

Example ■ Palladium chloride 10■-mol and tellurium dioxide 10■mol
-mol in 80 l of 6N-hydrochloric acid, and add 4 to 6
20 g of mesh activated carbon was added and slowly dried on a hot water bath.

This was further dried at 150°C for 2 hours with a stream of nitrogen, then reduced at room temperature with nitrogen saturated with water and methanol at a flow rate of 11 grams, at 900°C for 2 hours, and then at 400°C for 1 hour. , which was used as a catalyst.

The catalyst prepared as above was prepared with an inner diameter of 20 mm and a length of 300 m.
m+7) A jacketed reactor made of SUS 316L was filled, and the reactor temperature was maintained at 100°C.

This was supplemented with 10 ppm (wt) of formic acid and 0.0 elemental sulfur.
Acetic acid 40 each containing 375 wt%? / hr, butadiene (contains 20 pprn pt-butylcatechol and lppm vinylcyclohexene) 15 y/
hr, and oxygen-containing gas (02 in N2 is 3vo1%)
16 ONl/hr was passed from the top of the reactor at a pressure of 40 ky/crAG.

In this case, the amount of sulfur for butadiene is 1000 p
It is pm.

The reaction liquid flowing out from the bottom of the reactor was cooled to 20°C to remove dissolved butadiene, and then analyzed by gas chromatography.

As a result, the reaction solution contained 16 wt % of 1.4-diacetoxybutene-2.

When the reaction was continued under these conditions, ioo.

1,4-diacetoxybutene in the reaction solution produced after hours.
The amount of 2 decreased to 8 wt%.

Example 2 The reaction was carried out in the same manner as in the previous example, except that the amount of elemental sulfur relative to butadiene was changed to the amount shown below,
The time required for the amount of 1,4-diacetoxybutene-2 in the produced reaction solution to decrease to 8 wt% was determined.

The results are shown below. Example 3 After separating the butadiene obtained in Example 1, the product 40k
g is made of 5US316L with an inner diameter of 50mm and a height of 3m (SUS
The mixture was charged into the bottom of a 316L batch distillation column (packed with Dickson packing), and acetic acid was first distilled off at a pressure of 150 mmHg, and then diacetoxybutene was distilled off at a pressure of 50 mmHg to obtain 500 f of the bottom residue.

The entire amount of this was dissolved in 40 kg of fresh acetic acid to replace the raw acetic acid in Example 1, and the same operation as in Example 1 was carried out. As a result, the amount of 1,4-diacetoxybutene-1 in the product was halved. It took 700 hours to complete.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the effect of the amount of elemental sulfur on the acetoxylation reaction catalyst, where the vertical axis represents the deactivation rate of the catalyst (the time when the initial activity reaches 172), and the horizontal axis represents the amount of elemental sulfur per part by weight of butadiene. Represents the amount of sulfur. FIG. 2 is a diagram showing the effect of temperature on the acetoxylation reaction catalyst when 1000 ppm [by weight] of elemental sulfur is added, where the vertical axis represents the deactivation rate of the catalyst and the horizontal axis represents the reaction temperature. FIG. 3 is a process diagram showing an example of an embodiment of the present invention. In the figure, ■ indicates a dissolution tank, ■ indicates a preheater, ■ indicates a reactor, ■ indicates a gas-liquid separator, and V, VI, and ■ indicate a distillation column.

Claims (1)

[Scope of Claims] 1. A method for producing diacetoxybutene, which comprises catalytically reacting butadiene, acetic acid, and oxygen or an oxygen-containing gas in the presence of a supported palladium-based catalyst and elemental sulfur. 2 Produce diacetoxybutene by catalytically reacting butadiene, vinegar solution, and oxygen or oxygen-containing gas in the presence of a supported palladium-based catalyst and elemental sulfur, and distilling butadiene, acetic acid, and the generated diacetoxybutene from the reaction product. A method for producing diacetoxybutene, which comprises separating and supplying at least a part of the obtained distillation residue to an acetoxylation reaction zone.