CA1094099A - Process for producing diacetoxybutene - Google Patents
Process for producing diacetoxybuteneInfo
- Publication number
- CA1094099A CA1094099A CA280,060A CA280060A CA1094099A CA 1094099 A CA1094099 A CA 1094099A CA 280060 A CA280060 A CA 280060A CA 1094099 A CA1094099 A CA 1094099A
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- Prior art keywords
- butadiene
- gas
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- tower
- fed
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/04—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides onto unsaturated carbon-to-carbon bonds
- C07C67/05—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides onto unsaturated carbon-to-carbon bonds with oxidation
- C07C67/055—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides onto unsaturated carbon-to-carbon bonds with oxidation in the presence of platinum group metals or their compounds
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- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Diacetoxybutene is produced by reacting butadiene, acetic acid and oxygen in the presence of a palladium type catalyst supported on a carrier wherein a mixed gas of oxygen and an inert gas is used as the oxygen source, the reaction is carried out in an acetoxylation zone under a pressure of 20 to 300 Kg/cm2 G., the reaction mixture is separated by the gas-liquid separation, a part of the separated gas is recycled to the acetoxylation zone, the remainder of the gas is fed to a first butadiene absorption tower to absorb butadiene in acetic acid under a pressure of 20 to 300 Kg/cm2 G., the separated liquid is distilled in a butadiene recovery tower after reducing the pressure to 0 to 20 Kg/cm2 G., the gas containing butadiene discharged from the recovery tower is fed into a second butadiene absorption tower to absorb butadiene into acetic acid under a pressure lower than that at the top of the recovery tower and the acetic acids containing butadiene which are discharged from the first and second butadiene absorption towers are fed into the acetoxyla-tion zone.
Diacetoxybutene is produced by reacting butadiene, acetic acid and oxygen in the presence of a palladium type catalyst supported on a carrier wherein a mixed gas of oxygen and an inert gas is used as the oxygen source, the reaction is carried out in an acetoxylation zone under a pressure of 20 to 300 Kg/cm2 G., the reaction mixture is separated by the gas-liquid separation, a part of the separated gas is recycled to the acetoxylation zone, the remainder of the gas is fed to a first butadiene absorption tower to absorb butadiene in acetic acid under a pressure of 20 to 300 Kg/cm2 G., the separated liquid is distilled in a butadiene recovery tower after reducing the pressure to 0 to 20 Kg/cm2 G., the gas containing butadiene discharged from the recovery tower is fed into a second butadiene absorption tower to absorb butadiene into acetic acid under a pressure lower than that at the top of the recovery tower and the acetic acids containing butadiene which are discharged from the first and second butadiene absorption towers are fed into the acetoxyla-tion zone.
Description
10940!99 The present inVention relates to a process for producing diacetoxybutene from butadiene in the presence of a palladium type catalyst. More particularly, the present invention relates to a process for producing diacetoxybutene with improvements of an acetoxylation system, a butadiene recovery system and a waste gas treating system.
It is known to produce diacetoxybutene by reacting butadiene, acetic acid and oxygen or an oxygen-containing gas by contact in the presence of a palladium type catalyst. Various methods have been proposed.
The active ingredients of oxygen, butadiene and acetic - acid are included in the waste gas discharged from the acetoxyla-tion system and in the gas discharged from a purification system for the reaction mixture produced by the acetoxylation. When the gases are discharged without any treatment, an economical loss and a pollution problem are disadvantageously caused, and accordingly, it is necessary to effectively recover the active ingredients and to reuse them.
It is known to recover butadiene from the gases discharged out of the systems by absorbing butadiene into acetic acid. However, when all of the unreacted butadiene is absorbed in one absorption tower, it is necessary to compress the feed gas fed to the absorption tower so as to increase the pressure or to use a large amount of acetic acid. It is relatively difficult to compress the feed gas to recover butadiene in one absorption tower and it is necessary to use a special compressor such as a turbo-compressor with liquid film shaft seal. Again, when a large amount of acetic acid is used for the absorption, the amount of acetic acid fed with the butadiene into the reactor is too high and it is necessary to recover acetic acid or to separate butadiene from the acetic acid by stripping, and accordingly, the energy required for the operation is increased.
~0940~9 Accordingly, it is not advantageous to treat the gases in one absorption tower.
When the gas discharged from the acetoxylation system is compressed by a compressor and is recycled to the acetoxylation system, oxygen in the gas can be effectively used. However, the gas includes corrosive acetic acid and polymerizable butadiene whereby a type of the compressor is limited.
The present invention provides a process for producing diacetoxybutene with recycling active ingredients especially butadiene and oxygen included in the waste gas to provide an acetoxylation system of high efficiency.
The present invention also provides a process for producing diacetoxybutene by reacting butadiene, acetic acid and an oxygen-containing gas in the presence of a palladium type catalyst with a carrier in high industrial efficiency.
According to the present invention there is provided a process for producing diacetoxybuteneby reacting butadiene, acetic acid and an oxygen source in the presence of a palladium type catalyst supported on a carrier which compries;
reacting said compounds in an acetoxylation zone at a pressure of 20 to 300 Kg/cm2 G. using a mixed gas of oxygen and an inert gas as the oxygen source; subjecting the reaction mixture to a gas-liquid separation; recycling a part of the separated gas into the acetoxylation zone; feeding the remainder of the separated gas into a first butadiene absorption tower to absorb butadiene into acetic acid under a pressure of 20 to 300 Kg~cm2 G.;
distilling the separated liquid in a butadiene recovery tower after decreasing the pressure to 0 to 20 Kg/cm2G.; feeding the butadiene-containing gas discharged from the recovery tower into a second butadiene absorption tower to absorb butadiene into acetic acid under the pressure less than the pressure at the top of the butadiene recovery tower; and recycling the ~0~4099 butadiene-containing acetic acid discharged from the flrst and second absorption towers, to the acetoxylation zone for use in the acetoxylation.
In one embodiment of the present invention there is provided a process for producing diacetoxybutene by reacting butadiene, acetic acid and an oxygen source in the presence of a palladium type catalyst with a carrier which comprises; reacting the compounds in an acetoxylation zone having a pressure of 20 to 300 Kg/cm2 G. using a mixed gas of oxygen and an inert gas as the oxygen source; subjecting the reaction mixture to a gas~ uid separation; compressing the separated gas bya turbo-compressor with liquid film shaft seal; recycling a part of the compressed gas to the acetoxylation zone; feeding the remainder of the compressed gas into a first butadiene absorption tower to absorb butadiene into acetic acid under a pressure of 20 to 300 Kg/cm2 G.; feeding the gas discharged from the butadiene absorption tower through the shaft seal part of the compressor into the compressor; distilling the separated liquid by a butadiene recovery tower after decreasing the pressure to 0 to 2~ Kg/cm G.;
feeding the butadiene-containing gas discharged from the recovery tower into a second butadiene absorption tower to absorb butadiene into acetic acid under the pressure less than the pressure at the top of the butadiene recovery tower; and recycling the butadiene-containing acetic acid discharged from the first and second absorption towers, to the acetoyxlation zone to use it in the acetoxylation.
It is preferably to use butadiene having high purity as the starting material in the acetoxylation. The butadiene need not to be pure and can be one in the Industrial Standard or one containing an inert gas such as nitrogen, argon, methane or ethane.
` 1094099 The quality of acetic acid as the starting material is not limited but acetic acid in Japanese Industrial Standard is satisfactorily used. From the viewpoint of the selectivity in the acetoxylation, the water content in acetic acid is preferably less than 20 wt.% and from the viewpoint of the material of the ~ reactor, the content of formic acid in acetic acid is preferably - less than 1.0 wt. %. As the acetic acid source, the butadiene-containing acetic acid obtianed by absorbing butadiene in the first and second butadiene-absorption towers can be used as well as fresh acetic acid. The amount of acetic acid is in a range from stoichiometric amount to 60 moles per 1 mole of butadiene.
Oxygen is used in a form of the mixed gas of oxygen and an inert gas such as nitrogen or argon, especially air.
It is however always necessary to prevent a formation of explosive gas in the reactor. The concentration of oxygen in the gas fed into the acetoxylation zone, that is the total gas of the mixed gas and the recycled gas is usually in a range of 0.1 to 15 vol.%, - preferably 1 to 10 vol. %, especially 3 to 6 vol. %.
The solid catalyst used in the acetoxylation is preferably a catalyst of palladium metal alone or together with a catalytic metal promotor selected from the group consisting of Bi, Se, Sb, and Te which is supported on a carrier. The carrier can be selected as desired. Suitable carriers include silica gel, silica alumina, alumina, clay, bauxite, magnesia, diatomaceous earth and pumice. The amounts of the catalytic metals in the catalyst are usually 0.1 to 20 wt. % of Pd, preferably 1 to 4 wt. %
and 0.01 to 30 wt. % of the promoter catalytic metal. The acetoxylation can be carried out by various methods and especially in a fixed bed.
In the process of the present invention, it is necessary to carry out the acetoxylation under a pressure of 20 to 300 Kg/cm2 G. When the pressure is slightly lower than the limit, 109409g the reaction velocity is not high enough to attain the industrial advantage. From the viewpoints of the economical strength of the reactor and the safety, it is not preferably to have a pressure higher than 300 Kg/cm2 G. The pressure is usually selected from the range of 40 to 150 Kg/cm G. The reaction temperature is usually in a range of 40 to 180C preferably 60 to 120C. When the temperature is too low, enough reaction velocity can not be attained whereas when the temperature is too high, the disadvantageous side reactions such as a combustion of butadiene and acetic acid, and a polymerization of butadiene are caused.
The butadiene included in the waste gases from the acetoxylation and the treatment of the reaction mixture is absorbed into acetic acid in the two butadiene-absorption towers maintained in the specific pressure according to the process of the present invention. The acetic acid used in the absorption is not limited and can be a commercial product including acetic acid recovered from the systems such as the acetic acid recovered from the diacetoxybutene manufacture step or the acetic acid formed by hydrolysis of diacetoxybutene. The butadiene-absorption towers can be the conventional towers used for the conventional absorption such as a packed tower, a plated tower and a spray tower.
In the process of the present invention, the reaction mixture formed by the acetoxylation is subjected to the gas-liquid separation. A part of the separated gas is recycled to the acetoxylation zone and the remainder of the gas is fed into the first butadiene absorption tower which is operated under a pressure higher than 20 Kg/cm2 G., preferably in the range 20 to 300 Kg/cm2 G., especially 40 to 150 Kg/cm2 G. to absorb butadiene into acetic acid. The operation temperature in the first absorption tower is in the range of 10 to 50C, preferably 20 to 40C.
The separated gas is rec~cled to the acetoxylation zone at the rate of 5 to 200 parts peX one part of the gas fed into the first butadiene absorption tower. Though the content of butadiene in the separated gas ia remarkably low such as 0.3 to 1.7 vol. ~, when butadiene is absorbed into acetic acid under the above-mentioned high pressure, the amount ofacetic - acid can be decreased to give the economical advantage.
I The gas is separated from the reaction mixture and the remaining liquid components are distilled after reducing the pressure to 0 to 20 Kg/cm2 G., preferably 2 to 10 Kg/cm G.
The liquid components of the reaction mixture are distilled in the butadiene recovery tower to distil off the dissolved butadiene as a gas from the top of the tower. The distillation tower is operated under a pressure of 0.05 to 4 Kg/cm2 G., preferably 0.2 to 1 Kgjcm2 G. The temperature at the bottom of the distillation tower is 118 to 140C, preferably 120 to 130C.
When the distillation is carried out at higher than 140C, the disadvantageous side reactions of the formation of the polymer and decomposition of the product may be caused, and an expensive anticorrosive material should be used. This is not economical.
The butadiene-containing gas discharged from the top of the distillation tower is fed into the second butadiene absorption tower which is operated at a pressure lower than the pressure at the top of the distillation tower, preferably 0 to 4 Kg/cm2 G., especially 0.2 to 1 Kg/cm2 G. to absorb buta-diene into acetic acid. The operation temperature of the second butadiene absorption tcwer is in a range of 10 to 50C, preferably 20 to 40C.
Thecontent of butadiene in the gas discharged from the distillation tower is high as 30 to 90 vol. % whereby even though it is absorbed under relatively low pressure, a large amount of acetic acid is not needed and satisfactory absorbing effect can be attained. Butadiene absorbed into acetic acid in the two lO9A099 butadiene absorption towers is fed into the acetoxylation zone.
The gas liquid separation for the reaction mixture of the acetoxylation can be attained by only one separation in certain condition, however, it can be carried out by two or more separations in different conditions. For example, the gas separated by thefirst gas-liquid separation followed by the acetoxylation is subjected to the second gas-liquid separation together with the butadiene-containing acetic acid discharged from the first butadiene absorption tower at the temperature of 20 to 60C lower than that ofthe first gas-liquid separation.
A part of the separated gas is fed into the acetoxylation zone and the remainder of the separated gas is fed into the first butadiene absorption tower. The separated liquid is fed after reducing the pressure, with the gas discharged from the butadiene recovery tower into the second butadiene absorption tower to treat it as described.
In the process of the present invention, a part of the gas separated by the gas-liquid separation of the reaction mixture of the acetoxylation is recycled to the acetoxylation system and remainder of the gas is fed into the first butadiene absorption tower. In the operation, it is preferable to use a turbo-compressor with liquid film shaft seal. In order to recycle or to feed the gas, a compressor is generally used. But as the separa-ted gas includes oxygen, corrosive acetic acid and a polymerizable butadiene, in order to maintain the safety operation for a long time, it is preferabe to prevent contact of the oxidzing gas with a sliding part of the compressor and a moving contact part causing trouble due to corrosion of the material, and the clogging of the compressor when a reciprocating compressor is used.
For the purpose, it is preferably to use a turbo-compressor having no sliding part and moving contact part in the `` 1094099 oxidizing gas atmosphere, i.e. an axial flow type or centrifugal type compressor. The turbo-compressors have VariouS kinds of the shaft seal parts. In the process of the invention, it is preferable to use the turbo-compressor with liquid film shaft seal which can be both side supported with bearlng ty~pe or cantilever type. It is optimum to use the cantilever type turbo-compressor with liquid film shaft seal.
The pressure of the gas discharged from the compressor is preferably 2 to 8 Kg/cm2, especially 3 to S Kg/cm2 higher than the sùcking pressure. When!the sucking pressure is in a range of 2G to 300 Kg/cm2 G. preferably 40 to 150 Kg/cm2 G., the compression ratio of the recycling gas (discharge pressure to suction pressure) may be less than l.4, preferably less than 1.2.
The turbo-compressor has lower compression ratio for each step in comparison with the other compressors such as a reciprocating compressor. However, the desirable compression ratio can be easily attained by the turbo-compressor used in the present invention. When the compression ratio is lower than l.2, the cantilever type turbo-compressor with liquid film shaft seal can be used in one step for compression.
A lubricant oil is usually used as the sealing liquid for the compressor. When the gas containing a polymerizable butadiene is compressed in the process of the invention, the clogging of the oil is caused at the shaft seal part, if the compressed gas is directly contacted with the sealing liquid, such as sealing oil. Accordingly, it is necessary to prevent the contact of the sealing oil with the compressed gas by feeding a clean gas whichdoes not cause such trouble. Air compressed in high pressure which is used in the acetoxylation cannot be used as the clean gas source because of the danger of explosion.
Nitrogen is difficult to use as the clean gas because of an " 1094099 unecon~mical disadvantage though the danger of explosion is not considered. In the process of the present invention, a part of the compressed recycling gas is treated with acetic acid to remove butadiene by the absorption, and the resulting gas can be used as the clean gas. It is preferable to directly use the gas discharged fromthe first butadiene absorption tower. It is unnecessary to remove the acetic acid entrained with the discharged gas. However, when acetic acid is absorbed into water, the corrosive property of the gas is advantageously eliminated.
It is necessary to impart the pressure for feeding the clean gas to be higher than the pressure at the shaft seal part in order to feed the clean gas into the compressor. In accordance with the process of the invention to feed the gas discharged from the first absorption tower as the clean gas source into the compressor, the pressure of the recycling gas at the discharging part is several Kg/cm2 higher than the pressure at the shaft sealing part. The discharged recycling gas is fed into the first butadiene ab~orption tower which is usually operated under the pressure at the discharge to about 1 Kg/cm lower than the discharge pressure. The gas discharged from the absorption tower is fed into the compressor. When the pressure in the absorption tower is too low below the range so that the pressure of the discharged gas is lower than the pressure at the shaft seal part, the discharged gas is compressed as desired and is fed into the compressor in the process of the invention. The gas cannot be directly fed into the discharging part. Two steps of labyrinthes are disposed between the oil film seal and the gas in the compressor and the suction side is connected through a uniform pressure pipe to the middle part between the labyrinthes. The cleaned compressed gas is fed through the first labyrinth to the middle part between the first ~094099 labyrinth to the middle part between the first and second labyrinthes. The gas is mixed with the gas in the compressor leaked through the second labyrinth and the mixed gas is fed through the uniform pressure pipe into the suction part, and is further fed into the discharge part. It is possible to use the restrictive rings instead of the labyrinth.
The present invention will be further illustrated by way of the accompanying drawings in which;
Figure 1 is a flow sheet for illustrating one embodiment of the process of the present invention.
Figure 2 is a partial enlarged view of the both side supported with the bearing type turbo-compressor with liquid film shaft seal and VII represents an oil film seal, VIII
designates labyrinth.
Referring to Figure 1, the reference I designates the acetoxylation zone; II designates the gas-liquid separator;
III designates a butadiene recovery tower; IV designates the both - side supported with bearing type turbo-compressor with liquid film shaft seal; V designates the first butadiene absorption tower and VI designates the second butadiene absorption tower.
The starting materials of butadiene, acetic acid and the oxygen containing gas is fed through the conduit ~ into the reactor (I) to complete the acetoxylation. The resulting reaction mixture is fed through the conduit ~ into the gas-liquid separator (II) to separate the gas from the liquid.
The separated liquid is fed through the conduit ~ into the butadiene recovery tower (III) after reducing the pressure.
The liquid containing the main components of 1,4-diacetoxybutene and acetic acid are discharged from the bottom of the tower and is fed through the conduit ~ into the deacetic acid tower (not shown) to obtain the liquid containing the main componen~
of 1,4-diacetoxybutene. The acetic acid discharged from the top of the deacetic acid tower is advantageously fed into the butadiene absorption tower after separating water therefxom-.
The butadiene containing gas discharged from the top of the butadiene recovery tower is fed through the conduit into the second absorption tower (VI). Butadiene is absorbed into acetic acid fed through the conduit ~ and the butadiene-containing acetic acid is discharged from the bottom of the tower and it is fed through the conduit ~ into the acetoxylation zone. The gas discharged from the top of the tower is purged through ~he conduit ~ out of the system. The separated gas discharged from the gas-liquid separator ~II) is cooled and is fed through the concuit ~ into the sucking part of the compressor (IV). The pressurized oxidizing gas is obtained from the discharge part.
- A part of the oxidizing gas is fed through the conduit ~ into the first absorption tower (V) and the remainder of the gas is fed through the part ~ into the acetoxylation zone.
In the first absorption tower, butadiene is absorbed into acetic acid fed through the conduit ~ . The butadiene containing acetic acid is discharged from the bottom of the tower and it is fed through the conduit ~ into the acetoxylation zone.
When both sides supported with bearing type turbo-compressore is used, a part of the gas discharged from the top of the tower is recycled as the clean gas to the shaft seal part of the compressor (IV) and the remainder of the gas is purged together with the waste gas discharged from the top of the second absorption tower out of the system. A half of the clean gas is discharged together with the shaft sealing oil from the shaft seal part of the compressor. The clean gas is combined with the purged gas from the absorption tower and the mixed gas is purged out of the system. It is preferable to absorb acetic acid component in the purged gas into water before purging it.
Figure 2 is a partial enlarged view of the both side supported with bearing type turbo-compressor with liquid film shaft seal (In Figure 1 (IV)) wherein the reference VII designates an oil film seal and VIII designates a labyrinth.
A half the clean gas fed through the conduit ~ is purged through the conduit ~ together with the sealing oil fed through the conduit ~ out of the system. The remaining half of the clean gas is fed into the middle part of the two steps of the~labyrinthes and is fed together with the gas in the compressor through the uniform pressure pipe into the suction part of the compressor and then it is fed into the discharge part. The gas is combined with the gas being compressed which is fed through the conduit ~ , and through the conduit ~ , a part of the mixed gas is fed into the first absorption tower and the remainder of the gas is recycled to the acetoxylation zone.
In accordance with the process of the present invention, the acetoxylation is carried out under a reaction pressure of 20 to 300 Kg/cm2 G. and two absorption towers at high pressure and low pressure are provided whereby the gas discharged from the butadiene recovery tower can be treated without the compression to completely recover butadiene with acetic acid needed for the acetoxylation. In accordance with the process of the present invention, the recycle gas is compressed whereby the oxidizing gas can be recycled to the acetoxylation zone in safety with advantage.
Moreover and preferably when a part of the gas discharged from the outlet is passed through the absorption tower to absorb butadierieinto acetic acid and a part of the gas discharged from the absorption tower is fed into the compressor, the recovery of butadiene and the recovery of oxygen in the waste gas can be simultaneously attained by one absorption tower.
The process of the present invention will be further illustrated in detail by the following Example in which a part means a part by weight unless otherwise specified.
Example:
Butadiene, air, recycle gas and recycle acetic acid were respectively fed into an acetoxylation zone at 50C under a pressure of 93 Kg/cm2 G. at the rates of 1400, 2290, 63,630 and 25,450 parts per 1 hour. The acetoxylation zone consisted of two of reactors made of SUS 316 having an inner diameter of 1800mm and a height of 8000mm which are connected. In each reactor, 4500 parts of a coconut shell active charcoal (4 to 6 mesh) which supports palladium and tellurium was packed. At the output of the acetoxylation zone, the pressure was 91 Kg/cm2 G. and the temperature was 80C.
At the bottom of the reactor, the first gas-liquid separation of the reaction mixture was carriedout under conditions to obtain the liquid containing main components of 1,4-diacetoxy-butene (13.7 wt.~) and acetic acid at a rate of 27,240 parts/hr.
and the gas containing oxygen and butadiene at a rate of 65,530 parts/hr.. The liqui-d was fed into the butadiene recovery tower after reducing the pressure to the atmosphereic pressure. The gas containing 20.4 wt.~ of butadiene was obtained from the top of the butadiene recovery tower at a rate of 1,120 parts/hr.
and the bottom containing 1,4-diacetoxybutene (14.3 wt.%) and acetic acid was obtained from the bottom of the tower at a rate of 26.120 parts/hr.. The butadiene recovery tower was made of SUS 316 and had an inner diameter of lOOOmm and a height of 7000mm and had ten plates of perforated plate trays and was equipped with a condenser and a reboiler. The operation of the recovery tower was carried out under atmospheric pressure at the top of the tower and a recycling ratio of 0.05. The bottom was consequently fed into the deacetic acid tower to obtain acetic acid having a --` 109~099 a purity of 98.5 wt.% from the top of the tower and to obtain 1,4-diacetoxybutene having a purity of 86.5 wt.% from the bottom of the tower.
The gas discharged from the acetoxylation zone at a rate of 65,530 parts/hr. was combined w1th the liquid contain-ing butadiene and acetic acid as the main component which was discharged from the first butadiene absorption tower under a pressure of 90 Kg/cm G. at a rate of 2,470 parts/hr. and the mixture was cooled to 45C and was separated by the second gas-liquid separation to obtain the separate gas containing 4.95 wt. %
of oxygen and nitrogen as the main component at a rate of 65,130 parts/hr., and to obtain the separated liquid containing acetic acid as the main component at a rate of 2870 parts/hr.
After reducing the pressure of the separated liquid to atmospheric pressure, the liquid was fed together with the gas discharged from the butadiene recovery tower at a rate of 1120 parts/hr. into the bottom of the second butadiene absorption tower. Acetic acid at 35C was fed from the top tower under atmospheric pressure at a rate of 21,970 parts/hr. to counter-currently contact the gas with the liquid in the tower. The , second butadiene absorption tower was made of SUS 316 and had an inner diameter of lOOOmm and a height of lSOOOmm. The operation was carriedout at 35C under atmospheric pressure to obtain the acetic acid containing butadiene from the bottom of the tower at a rate of of 25,450 parts/hr., and to obtain the waste gas containing 100 ppm (vol.) of butadiene from the top of the tower at a rate of 510 parts/hr.. The waste gas was washed in a water washing tower before discharging.
The separated gas under a pressure of gO Kg/cm2G.
obtained by the second gas-liquid separation at a rate of 64,130 parts/hr. was fed into the suction part of the turbo-compressor with liquid film shaft seal (both sides supported with bearing -` ~094099 type one step; 10,000 r.p.m. manufactured by Mitsubishi Heavy Industries K.K.) to obtain the recycle gas having a higher pressure of 96 Kg/cm2 G. from the discharge part at a rate of 65,630 parts/hr. A part of the recycle gas at a rate of 2,000 parts/hr. was fed into the bottom of the first butadiene absorption tower and remainder was recycled to the acetoxylation zone. Acetic acid at 35C was fed from the top of the absorption tower under the pressure of 96 Kg/cm2 G. at a rate of 2,430 parts/hr. to counter-currently contact the gas with the liquid 1~ in the tower, to obtain the waste gas containing 100 ppm (vol.) of butadiene from the top of the tower at a rate of 1,960 parts/hr.
The waste gas at a rage of 1,000 parts/hr. was divided into each of the gas at a rate of 500 parts/hr. and was recycled as the clean gas to the shaft seal part of the compressor. The acetic acid containing butadiene was obtained from the bottom of the first butadiene absorption tower at a rate of 2,470 parts/hr.
and it was recycled to the second gas-liquid separator as described. The first butadiene absorption tower was made of SUS 316 and had an inner diameter of 500mm and a height of lOOOOmm. The operation was carried out at 35C under the pressure of 96 Kg/cm G. From both the shaft seal parts of the compressor, the clean gas was discharged at a rate of 250 parts/hr., respectively together with the seal oil, and it was washed with a water washing tower before discharging it.
It is known to produce diacetoxybutene by reacting butadiene, acetic acid and oxygen or an oxygen-containing gas by contact in the presence of a palladium type catalyst. Various methods have been proposed.
The active ingredients of oxygen, butadiene and acetic - acid are included in the waste gas discharged from the acetoxyla-tion system and in the gas discharged from a purification system for the reaction mixture produced by the acetoxylation. When the gases are discharged without any treatment, an economical loss and a pollution problem are disadvantageously caused, and accordingly, it is necessary to effectively recover the active ingredients and to reuse them.
It is known to recover butadiene from the gases discharged out of the systems by absorbing butadiene into acetic acid. However, when all of the unreacted butadiene is absorbed in one absorption tower, it is necessary to compress the feed gas fed to the absorption tower so as to increase the pressure or to use a large amount of acetic acid. It is relatively difficult to compress the feed gas to recover butadiene in one absorption tower and it is necessary to use a special compressor such as a turbo-compressor with liquid film shaft seal. Again, when a large amount of acetic acid is used for the absorption, the amount of acetic acid fed with the butadiene into the reactor is too high and it is necessary to recover acetic acid or to separate butadiene from the acetic acid by stripping, and accordingly, the energy required for the operation is increased.
~0940~9 Accordingly, it is not advantageous to treat the gases in one absorption tower.
When the gas discharged from the acetoxylation system is compressed by a compressor and is recycled to the acetoxylation system, oxygen in the gas can be effectively used. However, the gas includes corrosive acetic acid and polymerizable butadiene whereby a type of the compressor is limited.
The present invention provides a process for producing diacetoxybutene with recycling active ingredients especially butadiene and oxygen included in the waste gas to provide an acetoxylation system of high efficiency.
The present invention also provides a process for producing diacetoxybutene by reacting butadiene, acetic acid and an oxygen-containing gas in the presence of a palladium type catalyst with a carrier in high industrial efficiency.
According to the present invention there is provided a process for producing diacetoxybuteneby reacting butadiene, acetic acid and an oxygen source in the presence of a palladium type catalyst supported on a carrier which compries;
reacting said compounds in an acetoxylation zone at a pressure of 20 to 300 Kg/cm2 G. using a mixed gas of oxygen and an inert gas as the oxygen source; subjecting the reaction mixture to a gas-liquid separation; recycling a part of the separated gas into the acetoxylation zone; feeding the remainder of the separated gas into a first butadiene absorption tower to absorb butadiene into acetic acid under a pressure of 20 to 300 Kg~cm2 G.;
distilling the separated liquid in a butadiene recovery tower after decreasing the pressure to 0 to 20 Kg/cm2G.; feeding the butadiene-containing gas discharged from the recovery tower into a second butadiene absorption tower to absorb butadiene into acetic acid under the pressure less than the pressure at the top of the butadiene recovery tower; and recycling the ~0~4099 butadiene-containing acetic acid discharged from the flrst and second absorption towers, to the acetoxylation zone for use in the acetoxylation.
In one embodiment of the present invention there is provided a process for producing diacetoxybutene by reacting butadiene, acetic acid and an oxygen source in the presence of a palladium type catalyst with a carrier which comprises; reacting the compounds in an acetoxylation zone having a pressure of 20 to 300 Kg/cm2 G. using a mixed gas of oxygen and an inert gas as the oxygen source; subjecting the reaction mixture to a gas~ uid separation; compressing the separated gas bya turbo-compressor with liquid film shaft seal; recycling a part of the compressed gas to the acetoxylation zone; feeding the remainder of the compressed gas into a first butadiene absorption tower to absorb butadiene into acetic acid under a pressure of 20 to 300 Kg/cm2 G.; feeding the gas discharged from the butadiene absorption tower through the shaft seal part of the compressor into the compressor; distilling the separated liquid by a butadiene recovery tower after decreasing the pressure to 0 to 2~ Kg/cm G.;
feeding the butadiene-containing gas discharged from the recovery tower into a second butadiene absorption tower to absorb butadiene into acetic acid under the pressure less than the pressure at the top of the butadiene recovery tower; and recycling the butadiene-containing acetic acid discharged from the first and second absorption towers, to the acetoyxlation zone to use it in the acetoxylation.
It is preferably to use butadiene having high purity as the starting material in the acetoxylation. The butadiene need not to be pure and can be one in the Industrial Standard or one containing an inert gas such as nitrogen, argon, methane or ethane.
` 1094099 The quality of acetic acid as the starting material is not limited but acetic acid in Japanese Industrial Standard is satisfactorily used. From the viewpoint of the selectivity in the acetoxylation, the water content in acetic acid is preferably less than 20 wt.% and from the viewpoint of the material of the ~ reactor, the content of formic acid in acetic acid is preferably - less than 1.0 wt. %. As the acetic acid source, the butadiene-containing acetic acid obtianed by absorbing butadiene in the first and second butadiene-absorption towers can be used as well as fresh acetic acid. The amount of acetic acid is in a range from stoichiometric amount to 60 moles per 1 mole of butadiene.
Oxygen is used in a form of the mixed gas of oxygen and an inert gas such as nitrogen or argon, especially air.
It is however always necessary to prevent a formation of explosive gas in the reactor. The concentration of oxygen in the gas fed into the acetoxylation zone, that is the total gas of the mixed gas and the recycled gas is usually in a range of 0.1 to 15 vol.%, - preferably 1 to 10 vol. %, especially 3 to 6 vol. %.
The solid catalyst used in the acetoxylation is preferably a catalyst of palladium metal alone or together with a catalytic metal promotor selected from the group consisting of Bi, Se, Sb, and Te which is supported on a carrier. The carrier can be selected as desired. Suitable carriers include silica gel, silica alumina, alumina, clay, bauxite, magnesia, diatomaceous earth and pumice. The amounts of the catalytic metals in the catalyst are usually 0.1 to 20 wt. % of Pd, preferably 1 to 4 wt. %
and 0.01 to 30 wt. % of the promoter catalytic metal. The acetoxylation can be carried out by various methods and especially in a fixed bed.
In the process of the present invention, it is necessary to carry out the acetoxylation under a pressure of 20 to 300 Kg/cm2 G. When the pressure is slightly lower than the limit, 109409g the reaction velocity is not high enough to attain the industrial advantage. From the viewpoints of the economical strength of the reactor and the safety, it is not preferably to have a pressure higher than 300 Kg/cm2 G. The pressure is usually selected from the range of 40 to 150 Kg/cm G. The reaction temperature is usually in a range of 40 to 180C preferably 60 to 120C. When the temperature is too low, enough reaction velocity can not be attained whereas when the temperature is too high, the disadvantageous side reactions such as a combustion of butadiene and acetic acid, and a polymerization of butadiene are caused.
The butadiene included in the waste gases from the acetoxylation and the treatment of the reaction mixture is absorbed into acetic acid in the two butadiene-absorption towers maintained in the specific pressure according to the process of the present invention. The acetic acid used in the absorption is not limited and can be a commercial product including acetic acid recovered from the systems such as the acetic acid recovered from the diacetoxybutene manufacture step or the acetic acid formed by hydrolysis of diacetoxybutene. The butadiene-absorption towers can be the conventional towers used for the conventional absorption such as a packed tower, a plated tower and a spray tower.
In the process of the present invention, the reaction mixture formed by the acetoxylation is subjected to the gas-liquid separation. A part of the separated gas is recycled to the acetoxylation zone and the remainder of the gas is fed into the first butadiene absorption tower which is operated under a pressure higher than 20 Kg/cm2 G., preferably in the range 20 to 300 Kg/cm2 G., especially 40 to 150 Kg/cm2 G. to absorb butadiene into acetic acid. The operation temperature in the first absorption tower is in the range of 10 to 50C, preferably 20 to 40C.
The separated gas is rec~cled to the acetoxylation zone at the rate of 5 to 200 parts peX one part of the gas fed into the first butadiene absorption tower. Though the content of butadiene in the separated gas ia remarkably low such as 0.3 to 1.7 vol. ~, when butadiene is absorbed into acetic acid under the above-mentioned high pressure, the amount ofacetic - acid can be decreased to give the economical advantage.
I The gas is separated from the reaction mixture and the remaining liquid components are distilled after reducing the pressure to 0 to 20 Kg/cm2 G., preferably 2 to 10 Kg/cm G.
The liquid components of the reaction mixture are distilled in the butadiene recovery tower to distil off the dissolved butadiene as a gas from the top of the tower. The distillation tower is operated under a pressure of 0.05 to 4 Kg/cm2 G., preferably 0.2 to 1 Kgjcm2 G. The temperature at the bottom of the distillation tower is 118 to 140C, preferably 120 to 130C.
When the distillation is carried out at higher than 140C, the disadvantageous side reactions of the formation of the polymer and decomposition of the product may be caused, and an expensive anticorrosive material should be used. This is not economical.
The butadiene-containing gas discharged from the top of the distillation tower is fed into the second butadiene absorption tower which is operated at a pressure lower than the pressure at the top of the distillation tower, preferably 0 to 4 Kg/cm2 G., especially 0.2 to 1 Kg/cm2 G. to absorb buta-diene into acetic acid. The operation temperature of the second butadiene absorption tcwer is in a range of 10 to 50C, preferably 20 to 40C.
Thecontent of butadiene in the gas discharged from the distillation tower is high as 30 to 90 vol. % whereby even though it is absorbed under relatively low pressure, a large amount of acetic acid is not needed and satisfactory absorbing effect can be attained. Butadiene absorbed into acetic acid in the two lO9A099 butadiene absorption towers is fed into the acetoxylation zone.
The gas liquid separation for the reaction mixture of the acetoxylation can be attained by only one separation in certain condition, however, it can be carried out by two or more separations in different conditions. For example, the gas separated by thefirst gas-liquid separation followed by the acetoxylation is subjected to the second gas-liquid separation together with the butadiene-containing acetic acid discharged from the first butadiene absorption tower at the temperature of 20 to 60C lower than that ofthe first gas-liquid separation.
A part of the separated gas is fed into the acetoxylation zone and the remainder of the separated gas is fed into the first butadiene absorption tower. The separated liquid is fed after reducing the pressure, with the gas discharged from the butadiene recovery tower into the second butadiene absorption tower to treat it as described.
In the process of the present invention, a part of the gas separated by the gas-liquid separation of the reaction mixture of the acetoxylation is recycled to the acetoxylation system and remainder of the gas is fed into the first butadiene absorption tower. In the operation, it is preferable to use a turbo-compressor with liquid film shaft seal. In order to recycle or to feed the gas, a compressor is generally used. But as the separa-ted gas includes oxygen, corrosive acetic acid and a polymerizable butadiene, in order to maintain the safety operation for a long time, it is preferabe to prevent contact of the oxidzing gas with a sliding part of the compressor and a moving contact part causing trouble due to corrosion of the material, and the clogging of the compressor when a reciprocating compressor is used.
For the purpose, it is preferably to use a turbo-compressor having no sliding part and moving contact part in the `` 1094099 oxidizing gas atmosphere, i.e. an axial flow type or centrifugal type compressor. The turbo-compressors have VariouS kinds of the shaft seal parts. In the process of the invention, it is preferable to use the turbo-compressor with liquid film shaft seal which can be both side supported with bearlng ty~pe or cantilever type. It is optimum to use the cantilever type turbo-compressor with liquid film shaft seal.
The pressure of the gas discharged from the compressor is preferably 2 to 8 Kg/cm2, especially 3 to S Kg/cm2 higher than the sùcking pressure. When!the sucking pressure is in a range of 2G to 300 Kg/cm2 G. preferably 40 to 150 Kg/cm2 G., the compression ratio of the recycling gas (discharge pressure to suction pressure) may be less than l.4, preferably less than 1.2.
The turbo-compressor has lower compression ratio for each step in comparison with the other compressors such as a reciprocating compressor. However, the desirable compression ratio can be easily attained by the turbo-compressor used in the present invention. When the compression ratio is lower than l.2, the cantilever type turbo-compressor with liquid film shaft seal can be used in one step for compression.
A lubricant oil is usually used as the sealing liquid for the compressor. When the gas containing a polymerizable butadiene is compressed in the process of the invention, the clogging of the oil is caused at the shaft seal part, if the compressed gas is directly contacted with the sealing liquid, such as sealing oil. Accordingly, it is necessary to prevent the contact of the sealing oil with the compressed gas by feeding a clean gas whichdoes not cause such trouble. Air compressed in high pressure which is used in the acetoxylation cannot be used as the clean gas source because of the danger of explosion.
Nitrogen is difficult to use as the clean gas because of an " 1094099 unecon~mical disadvantage though the danger of explosion is not considered. In the process of the present invention, a part of the compressed recycling gas is treated with acetic acid to remove butadiene by the absorption, and the resulting gas can be used as the clean gas. It is preferable to directly use the gas discharged fromthe first butadiene absorption tower. It is unnecessary to remove the acetic acid entrained with the discharged gas. However, when acetic acid is absorbed into water, the corrosive property of the gas is advantageously eliminated.
It is necessary to impart the pressure for feeding the clean gas to be higher than the pressure at the shaft seal part in order to feed the clean gas into the compressor. In accordance with the process of the invention to feed the gas discharged from the first absorption tower as the clean gas source into the compressor, the pressure of the recycling gas at the discharging part is several Kg/cm2 higher than the pressure at the shaft sealing part. The discharged recycling gas is fed into the first butadiene ab~orption tower which is usually operated under the pressure at the discharge to about 1 Kg/cm lower than the discharge pressure. The gas discharged from the absorption tower is fed into the compressor. When the pressure in the absorption tower is too low below the range so that the pressure of the discharged gas is lower than the pressure at the shaft seal part, the discharged gas is compressed as desired and is fed into the compressor in the process of the invention. The gas cannot be directly fed into the discharging part. Two steps of labyrinthes are disposed between the oil film seal and the gas in the compressor and the suction side is connected through a uniform pressure pipe to the middle part between the labyrinthes. The cleaned compressed gas is fed through the first labyrinth to the middle part between the first ~094099 labyrinth to the middle part between the first and second labyrinthes. The gas is mixed with the gas in the compressor leaked through the second labyrinth and the mixed gas is fed through the uniform pressure pipe into the suction part, and is further fed into the discharge part. It is possible to use the restrictive rings instead of the labyrinth.
The present invention will be further illustrated by way of the accompanying drawings in which;
Figure 1 is a flow sheet for illustrating one embodiment of the process of the present invention.
Figure 2 is a partial enlarged view of the both side supported with the bearing type turbo-compressor with liquid film shaft seal and VII represents an oil film seal, VIII
designates labyrinth.
Referring to Figure 1, the reference I designates the acetoxylation zone; II designates the gas-liquid separator;
III designates a butadiene recovery tower; IV designates the both - side supported with bearing type turbo-compressor with liquid film shaft seal; V designates the first butadiene absorption tower and VI designates the second butadiene absorption tower.
The starting materials of butadiene, acetic acid and the oxygen containing gas is fed through the conduit ~ into the reactor (I) to complete the acetoxylation. The resulting reaction mixture is fed through the conduit ~ into the gas-liquid separator (II) to separate the gas from the liquid.
The separated liquid is fed through the conduit ~ into the butadiene recovery tower (III) after reducing the pressure.
The liquid containing the main components of 1,4-diacetoxybutene and acetic acid are discharged from the bottom of the tower and is fed through the conduit ~ into the deacetic acid tower (not shown) to obtain the liquid containing the main componen~
of 1,4-diacetoxybutene. The acetic acid discharged from the top of the deacetic acid tower is advantageously fed into the butadiene absorption tower after separating water therefxom-.
The butadiene containing gas discharged from the top of the butadiene recovery tower is fed through the conduit into the second absorption tower (VI). Butadiene is absorbed into acetic acid fed through the conduit ~ and the butadiene-containing acetic acid is discharged from the bottom of the tower and it is fed through the conduit ~ into the acetoxylation zone. The gas discharged from the top of the tower is purged through ~he conduit ~ out of the system. The separated gas discharged from the gas-liquid separator ~II) is cooled and is fed through the concuit ~ into the sucking part of the compressor (IV). The pressurized oxidizing gas is obtained from the discharge part.
- A part of the oxidizing gas is fed through the conduit ~ into the first absorption tower (V) and the remainder of the gas is fed through the part ~ into the acetoxylation zone.
In the first absorption tower, butadiene is absorbed into acetic acid fed through the conduit ~ . The butadiene containing acetic acid is discharged from the bottom of the tower and it is fed through the conduit ~ into the acetoxylation zone.
When both sides supported with bearing type turbo-compressore is used, a part of the gas discharged from the top of the tower is recycled as the clean gas to the shaft seal part of the compressor (IV) and the remainder of the gas is purged together with the waste gas discharged from the top of the second absorption tower out of the system. A half of the clean gas is discharged together with the shaft sealing oil from the shaft seal part of the compressor. The clean gas is combined with the purged gas from the absorption tower and the mixed gas is purged out of the system. It is preferable to absorb acetic acid component in the purged gas into water before purging it.
Figure 2 is a partial enlarged view of the both side supported with bearing type turbo-compressor with liquid film shaft seal (In Figure 1 (IV)) wherein the reference VII designates an oil film seal and VIII designates a labyrinth.
A half the clean gas fed through the conduit ~ is purged through the conduit ~ together with the sealing oil fed through the conduit ~ out of the system. The remaining half of the clean gas is fed into the middle part of the two steps of the~labyrinthes and is fed together with the gas in the compressor through the uniform pressure pipe into the suction part of the compressor and then it is fed into the discharge part. The gas is combined with the gas being compressed which is fed through the conduit ~ , and through the conduit ~ , a part of the mixed gas is fed into the first absorption tower and the remainder of the gas is recycled to the acetoxylation zone.
In accordance with the process of the present invention, the acetoxylation is carried out under a reaction pressure of 20 to 300 Kg/cm2 G. and two absorption towers at high pressure and low pressure are provided whereby the gas discharged from the butadiene recovery tower can be treated without the compression to completely recover butadiene with acetic acid needed for the acetoxylation. In accordance with the process of the present invention, the recycle gas is compressed whereby the oxidizing gas can be recycled to the acetoxylation zone in safety with advantage.
Moreover and preferably when a part of the gas discharged from the outlet is passed through the absorption tower to absorb butadierieinto acetic acid and a part of the gas discharged from the absorption tower is fed into the compressor, the recovery of butadiene and the recovery of oxygen in the waste gas can be simultaneously attained by one absorption tower.
The process of the present invention will be further illustrated in detail by the following Example in which a part means a part by weight unless otherwise specified.
Example:
Butadiene, air, recycle gas and recycle acetic acid were respectively fed into an acetoxylation zone at 50C under a pressure of 93 Kg/cm2 G. at the rates of 1400, 2290, 63,630 and 25,450 parts per 1 hour. The acetoxylation zone consisted of two of reactors made of SUS 316 having an inner diameter of 1800mm and a height of 8000mm which are connected. In each reactor, 4500 parts of a coconut shell active charcoal (4 to 6 mesh) which supports palladium and tellurium was packed. At the output of the acetoxylation zone, the pressure was 91 Kg/cm2 G. and the temperature was 80C.
At the bottom of the reactor, the first gas-liquid separation of the reaction mixture was carriedout under conditions to obtain the liquid containing main components of 1,4-diacetoxy-butene (13.7 wt.~) and acetic acid at a rate of 27,240 parts/hr.
and the gas containing oxygen and butadiene at a rate of 65,530 parts/hr.. The liqui-d was fed into the butadiene recovery tower after reducing the pressure to the atmosphereic pressure. The gas containing 20.4 wt.~ of butadiene was obtained from the top of the butadiene recovery tower at a rate of 1,120 parts/hr.
and the bottom containing 1,4-diacetoxybutene (14.3 wt.%) and acetic acid was obtained from the bottom of the tower at a rate of 26.120 parts/hr.. The butadiene recovery tower was made of SUS 316 and had an inner diameter of lOOOmm and a height of 7000mm and had ten plates of perforated plate trays and was equipped with a condenser and a reboiler. The operation of the recovery tower was carried out under atmospheric pressure at the top of the tower and a recycling ratio of 0.05. The bottom was consequently fed into the deacetic acid tower to obtain acetic acid having a --` 109~099 a purity of 98.5 wt.% from the top of the tower and to obtain 1,4-diacetoxybutene having a purity of 86.5 wt.% from the bottom of the tower.
The gas discharged from the acetoxylation zone at a rate of 65,530 parts/hr. was combined w1th the liquid contain-ing butadiene and acetic acid as the main component which was discharged from the first butadiene absorption tower under a pressure of 90 Kg/cm G. at a rate of 2,470 parts/hr. and the mixture was cooled to 45C and was separated by the second gas-liquid separation to obtain the separate gas containing 4.95 wt. %
of oxygen and nitrogen as the main component at a rate of 65,130 parts/hr., and to obtain the separated liquid containing acetic acid as the main component at a rate of 2870 parts/hr.
After reducing the pressure of the separated liquid to atmospheric pressure, the liquid was fed together with the gas discharged from the butadiene recovery tower at a rate of 1120 parts/hr. into the bottom of the second butadiene absorption tower. Acetic acid at 35C was fed from the top tower under atmospheric pressure at a rate of 21,970 parts/hr. to counter-currently contact the gas with the liquid in the tower. The , second butadiene absorption tower was made of SUS 316 and had an inner diameter of lOOOmm and a height of lSOOOmm. The operation was carriedout at 35C under atmospheric pressure to obtain the acetic acid containing butadiene from the bottom of the tower at a rate of of 25,450 parts/hr., and to obtain the waste gas containing 100 ppm (vol.) of butadiene from the top of the tower at a rate of 510 parts/hr.. The waste gas was washed in a water washing tower before discharging.
The separated gas under a pressure of gO Kg/cm2G.
obtained by the second gas-liquid separation at a rate of 64,130 parts/hr. was fed into the suction part of the turbo-compressor with liquid film shaft seal (both sides supported with bearing -` ~094099 type one step; 10,000 r.p.m. manufactured by Mitsubishi Heavy Industries K.K.) to obtain the recycle gas having a higher pressure of 96 Kg/cm2 G. from the discharge part at a rate of 65,630 parts/hr. A part of the recycle gas at a rate of 2,000 parts/hr. was fed into the bottom of the first butadiene absorption tower and remainder was recycled to the acetoxylation zone. Acetic acid at 35C was fed from the top of the absorption tower under the pressure of 96 Kg/cm2 G. at a rate of 2,430 parts/hr. to counter-currently contact the gas with the liquid 1~ in the tower, to obtain the waste gas containing 100 ppm (vol.) of butadiene from the top of the tower at a rate of 1,960 parts/hr.
The waste gas at a rage of 1,000 parts/hr. was divided into each of the gas at a rate of 500 parts/hr. and was recycled as the clean gas to the shaft seal part of the compressor. The acetic acid containing butadiene was obtained from the bottom of the first butadiene absorption tower at a rate of 2,470 parts/hr.
and it was recycled to the second gas-liquid separator as described. The first butadiene absorption tower was made of SUS 316 and had an inner diameter of 500mm and a height of lOOOOmm. The operation was carried out at 35C under the pressure of 96 Kg/cm G. From both the shaft seal parts of the compressor, the clean gas was discharged at a rate of 250 parts/hr., respectively together with the seal oil, and it was washed with a water washing tower before discharging it.
Claims (17)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for producing diacetoxybutene by reacting butadiene, an oxygen source and acetic acid in the presence of a palladium type catalyst supported on a carrier, the improvement in which a mixed gas of oxygen and an inert gas is used as the oxygen source; the reaction is carried out in an acetoxylation zone under the pressure of 20 to 300 Kg/cm2 G.;
the reaction mixture is subjected to the gas-liquid separation;
a part of the separated gas is recycled to the acetoxylation zone; the remainder of the gas is fed into a first butadiene absorption tower where butadiene is absorbed into acetic acid under the pressure of 20 to 300 Kg/cm2G.; the separated liquid is distilled in a butadiene recovery tower after reducing the pressure to 0 to 20 Kg/cm2 G.; the gas containing butadiene discharged from the recovery tower is fed into a second butadiene absorption tower to absorb butadiene into acetic acid under a pressure lower than the pressure at the top of the recovery tower; and the acetic acids containing butadiene which are discharged from the first and second butadiene absorption towers are fed into the acetoxylation zone.
the reaction mixture is subjected to the gas-liquid separation;
a part of the separated gas is recycled to the acetoxylation zone; the remainder of the gas is fed into a first butadiene absorption tower where butadiene is absorbed into acetic acid under the pressure of 20 to 300 Kg/cm2G.; the separated liquid is distilled in a butadiene recovery tower after reducing the pressure to 0 to 20 Kg/cm2 G.; the gas containing butadiene discharged from the recovery tower is fed into a second butadiene absorption tower to absorb butadiene into acetic acid under a pressure lower than the pressure at the top of the recovery tower; and the acetic acids containing butadiene which are discharged from the first and second butadiene absorption towers are fed into the acetoxylation zone.
2. A process according to Claim 1, wherein the separated gas is compressed by a turbo-compressor with liquid film shaft seal; a part of the compressed gas is recycled to the acetoxylation zone; the remainder of the compressed gas is fed into the first butadiene absorption tower where butadiene is absorbed into acetic acid under a pressure of 20 to 300 Kg/cm2G.
and the gas discharged from the absorption tower is fed as a clean gas through the shaft seal part of the compressor into the compressor.
and the gas discharged from the absorption tower is fed as a clean gas through the shaft seal part of the compressor into the compressor.
3. A process according to Claim 1, wherein the oxygen content in the total of the mixed gas and the separated gas recycled to the acetoxylation zone is in a range of 0.1 to 15 vol. %.
4. A process according to Claim 1, 2 or 3, wherein the mixed gas is air.
5. A process according to Claim 1, 2 or 3, wherein the temperature in the acetoxylation zone is in a range of 40 to 180°C.
6. A process according to Claim 1, 2 or 3, wherein the separated gas is recycled to the acetoxylation zone at the rate of 5 to 200 parts per 1 part of the gas fed into the first butadiene absorption tower.
7. A process according to Claim 1, 2 or 3, wherein the temperature in the first butadiene absorption tower is in a range of 10 to 50°C.
8. A process according to Claim 1, 2 or 3, wherein the butadiene recovery tower is operated at 118 to 140°C at the bottom of the tower under a pressure of 0.05 to 4 Kg/cm2 G. at the top of the tower.
9. A process according to Claim 1, 2 or 3, wherein the second butadiene absorption tower is operated at 10 to 50°C
under a pressure of 0 to 4 Kg/cm G. at the top of the tower.
under a pressure of 0 to 4 Kg/cm G. at the top of the tower.
10. A process according to Claim 1, 2 or 3, wherein the second butadiene absorption tower is operated at 20 to 40°C
under a pressure of 0.2 to 1 Kg/cm2 G.
under a pressure of 0.2 to 1 Kg/cm2 G.
11. A process according to Claim 1, 2 or 3, wherein the gas-liquid separation of the reaction mixture is carried out by two steps and the gas obtained by the first step gas-liquid separation is fed to the second step gas-liquid separation together with a part of the acetic acid containing butadiene discharged from the first butadiene absorption tower and the second step gas-liquid separation is carried out at the temperature lower than that of the first step.
12. A process according to Claim 1, 2 or 3, wherein the acetoxylation is carried out at 60 to 120°C under the pressure of 40 to 150 Kg/cm G.
13. A process according to Claim 1, 2 or 3, wherein the first butadiene absorption tower is operated at 20 to 40°C
under the pressure of 40 to 150 Kg/cm2 G.
under the pressure of 40 to 150 Kg/cm2 G.
14. A process according to Claim 1, 2 or 3, wherein the pressure of the separated liquid is reduced to 2 to 10 Kg/cm G.
15. A process according to Claim 1, 2 or 3, wherein the butadiene recovery tower is operated at 120 to 130°C at the bottom of the tower under the pressure of 0.2 to 1 Kg/cm2 G.
16. In a process for producing diacetoxybutene by reacting butadiene, an oxygen source and acetic acid in the presence of a palladium type catalyst supported on a carrier, the improvement in which a mixed gas of oxygen and an inert gas is used as the oxygen source; the reaction is carried out in an acetoxylation zone at 40 to 180°C under a pressure of 20 to 300 Kg/cm2 G.; the reaction mixture is subjected to the gas-liquid separation; the separated gas is compressed by a turbo-compressor with a liquid film shaft seal; a part of the compressed gas is recycled to the acetoxylation zone; the remainder of the compressed gas is fed into a first butadiene absorption tower to absorb butadiene at 10 to 50°C under a pressure of 20 to 300 Kg/cm2 G.;
the gas discharged from the absorption tower is fed as a clean gas through the shaft seal of the compressor into the compressor; the separated liquid is distilled by the butadiene recovery tower operated at 118 to 140°C at the bottom of the tower under a pressure of 0.05 to 4 Kg/cm2G. at the top of the tower after reducing the pressure to 0 to 20 Kg/cm2G.; the gas containing butadiene discharged from the tower is fed into the second butadiene absorption tower where butadiene is absorbed into acetic acid at 10 to 50°C under a pressure of lower than the pressure at the top of the recovery tower in a range of 0 to 4 Kg/cm2G.; and the acetic acids containing butadiene discharged from the first and second butadiene absorption towers are fed into the acetoxylation zone.
the gas discharged from the absorption tower is fed as a clean gas through the shaft seal of the compressor into the compressor; the separated liquid is distilled by the butadiene recovery tower operated at 118 to 140°C at the bottom of the tower under a pressure of 0.05 to 4 Kg/cm2G. at the top of the tower after reducing the pressure to 0 to 20 Kg/cm2G.; the gas containing butadiene discharged from the tower is fed into the second butadiene absorption tower where butadiene is absorbed into acetic acid at 10 to 50°C under a pressure of lower than the pressure at the top of the recovery tower in a range of 0 to 4 Kg/cm2G.; and the acetic acids containing butadiene discharged from the first and second butadiene absorption towers are fed into the acetoxylation zone.
17. In a process for producing diacetoxybutene by reacting butadiene, an oxygen source and acetic acid in the presence of a palladium type catalyst supported on a carrier, the improvement in which air is used as the oxygen source; the reaction is carried out in an acetoxylation zone at 60 to 120°C
under a pressure of 40 to 150 Kg/cm2 G.; the reaction mixture is subjected to the gas-liquid separation; the separated gas is compressed by a turbo-compressor with a liquid film shaft seal;
a part of the compressed gas is recycled to the acetoxylation zone; the remainder of the compressed gas is fed into a first butadiene absorption tower to absorb butadiene at 20 to 40°C
under a pressure of 40 to 150 Kg/cm2 G.; the gas discharged from the absorption tower is fed as a clean gas through the shaft seal of the compressor into the compressor; the separated liquid is distilled by the butadiene recovery tower operated at 120 to 130°C
at the bottom of the tower under a pressure of 0.2 to 1 Kg/cm2 G.
at the top of the tower after reducing the pressure to 2 to 10 Kg/
cm2 G.; the gas containing butadiene discharged from the tower is fed into the second butadiene absorption tower where butadiene is absorbed into acetic acid at 20 to 40°C under a pressure of lower than the pressure at the top of the recovery tower in a range of 0.2 to 1 Kg/cm2 G.; and the acetic acids containing butadiene discharged from the first and second butadiene absorption towers are fed into the acetoxylation zone.
under a pressure of 40 to 150 Kg/cm2 G.; the reaction mixture is subjected to the gas-liquid separation; the separated gas is compressed by a turbo-compressor with a liquid film shaft seal;
a part of the compressed gas is recycled to the acetoxylation zone; the remainder of the compressed gas is fed into a first butadiene absorption tower to absorb butadiene at 20 to 40°C
under a pressure of 40 to 150 Kg/cm2 G.; the gas discharged from the absorption tower is fed as a clean gas through the shaft seal of the compressor into the compressor; the separated liquid is distilled by the butadiene recovery tower operated at 120 to 130°C
at the bottom of the tower under a pressure of 0.2 to 1 Kg/cm2 G.
at the top of the tower after reducing the pressure to 2 to 10 Kg/
cm2 G.; the gas containing butadiene discharged from the tower is fed into the second butadiene absorption tower where butadiene is absorbed into acetic acid at 20 to 40°C under a pressure of lower than the pressure at the top of the recovery tower in a range of 0.2 to 1 Kg/cm2 G.; and the acetic acids containing butadiene discharged from the first and second butadiene absorption towers are fed into the acetoxylation zone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6809776A JPS52151115A (en) | 1976-06-10 | 1976-06-10 | Preparation of diacetoxybutene |
| JP68097/1976 | 1976-06-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1094099A true CA1094099A (en) | 1981-01-20 |
Family
ID=13363884
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA280,060A Expired CA1094099A (en) | 1976-06-10 | 1977-06-07 | Process for producing diacetoxybutene |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS52151115A (en) |
| CA (1) | CA1094099A (en) |
| DE (1) | DE2726125A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5839141B2 (en) * | 1978-02-08 | 1983-08-27 | ジェイエスアール株式会社 | Method for producing diacetoxybutene |
| JPS57139038A (en) * | 1981-02-23 | 1982-08-27 | Mitsubishi Chem Ind Ltd | Preparation of diacetoxybutene |
| JP2530333B2 (en) * | 1987-04-23 | 1996-09-04 | 三菱化学株式会社 | Method for producing unsaturated glycol diester |
-
1976
- 1976-06-10 JP JP6809776A patent/JPS52151115A/en active Granted
-
1977
- 1977-06-07 CA CA280,060A patent/CA1094099A/en not_active Expired
- 1977-06-10 DE DE19772726125 patent/DE2726125A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| JPS52151115A (en) | 1977-12-15 |
| JPS5542057B2 (en) | 1980-10-28 |
| DE2726125A1 (en) | 1977-12-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |