JPS61207356A - Apparatus for producing methyl ethyl ketone - Google Patents

Abstract

PURPOSE:To synthesize MEK, by using an apparatus for separating 1-butene from 2-butene and an isomerization apparatus to convert 2-butene to 1-butene as pretreatment steps, and oxidizing 1-butene in the presence of a catalyst liquid containing an oxygen complex. CONSTITUTION:The raw material 1 is treated first by a butadiene-removal apparatus 2 and then by an isobutene-separation apparatus 4. The obtained mixture of 1-butene and 2-butene is introduced into the 2-butene separation column 7, and only the 1-butene is introduced through the line 8 into the oxidation reaction column 14. The 2-butene is introduced into the dehydration column 21 and then into the isomerization reaction column 23 to convert a part of the 2-butene to 1-butene. After removing the heavy components, the product is returned to the upstream side of the 2-butene separation column 7 to increase the yield of 1-butene. EFFECT:The MEK yield can be improved to >=95% based on n-butene. The utility cost and the apparatus cost can be reduced compared with the process having the isomerization apparatus after the oxidation reaction column.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a methyl ethyl ketone production apparatus, and more particularly to a methyl ethyl ketone production apparatus capable of producing methyl ethyl ketone in good yield and at low cost.

(Prior Art) Conventionally, the synthesis method of methyl ethyl ketone (hereinafter referred to as MEK) that has been carried out industrially consists of n-butene (1-butene and 2 -butene) in the presence of concentrated sulfuric acid to synthesize 5ec-butyl alcohol,
The mainstream is the so-called sulfuric acid method, in which MEK is produced by dehydrogenating this 5ec-butyl alcohol in the presence of a catalyst. This method uses n-butene (1-butene, cis
-'L-Butene and trans-2-butene mixture) has the advantage of reacting with all the components, but the reaction process is complicated, and many reaction by-products and polymers are produced, and concentrated sulfuric acid is It has drawbacks such as the use of high-grade corrosion-resistant materials, which can lead to increased costs.

On the other hand, the applicant has previously reported on the MEK synthesis method.
A complex consisting of at least one catalyst component of a transition metal mirror capable of binding oxygen molecules to metal ions to form an oxygen complex, and a transition metal complex capable of binding butene to form a butene complex. We proposed a method for efficiently synthesizing MEK under mild conditions by oxidizing 1-butene activated by complex formation in the presence of water using a catalyst (Japanese Patent Application No. 1983).
9-122600). The metal complex catalyst is a complex capable of forming an oxygen complex by coordinating oxygen (MmX n
-L l> and a complex catalyst (M'm'Xn'・L I l l
) (where M is from group II of the periodic law,
Transition metals belonging to groups ■ to ■ or iron group □ of group 1,
X is a halogen such as Cll-1Br-1-, or BF
Anion such as 4-1PFc -, CH3COO-1S042-, L is an organic phosphorus compound, Mo is a transition metal belonging to the platinum group of group Ⅰ of the periodic table, Lo is a nitrile, an organic fluorine compound or an organic phosphorus compound, m , m', n, n" are numbers determined by the valence of the transition metal and anion, g
, z' indicates the coordination number).

Furthermore, in the above MEK synthesis method, the applicant has proposed that the raw material B
- Among the raw materials consisting of normal butene (1-butene and 2-butene) from which butadiene and isobutyne have been removed from the B fraction, 2-butene, which hardly contributes to the MEK production reaction, is isomerized to 1-butene. We proposed a process aimed at improving the yield of MEK based on the raw material normal butene (Japanese Patent Application No. 164787/1987).

(Problems to be Solved by the Invention) However, in the above process, the equilibrium conversion rate of 2-butene to 1-butene in the isomerization device is 10 to 20%.
However, the amount of butene recycled through the oxidation reaction tower, catalyst separation tower, and butene separation tower is extremely large, and the capacity of the tower and the amount of heat required in the reboiler and condenser are also large, resulting in lower utility costs and equipment costs. also becomes expensive,
It turned out that it was not possible to achieve sufficient benefits.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a methyl ethyl ketone production apparatus that achieves high yield and low manufacturing cost.

(Means for Solving the Problems) In short, the present invention comprises a raw material pretreatment step consisting of a butadiene removal device, a 1so-butene separation device, a 2-butene separation device, and a 2-butene isomerization device, and the oxidation reaction step The input raw material is almost 100% 1-butene, while the separated 2-butene is converted to 1-butene in an isomerization device in the pretreatment process and recycled.
This reduces equipment costs and utilities in the oxidation reaction process.

(Example) FIG. 1 is a diagram showing a process flow of a MEKil manufacturing apparatus showing an example of the present invention.

In the figure, the C4 fraction l, which is a raw material, mainly contains 2-butene (trans-2-butene and c i
5-2-butene) includes isobutyne and butadiene.

The raw material 1 is first introduced into a butadiene removal device 2, where butadiene is separated by a molecular sieve method or a cuprammonium acetate method, or converted to 1-butene by hydrogenation, and almost completely removed. Next, the raw material is introduced into an isobutyne separation device 4, where isobutyne 5 is separated from n-butene (l-butene and 2-butene) by taking advantage of its ability to be absorbed by about 65% sulfuric acid.

The steps up to the above are the same as the conventional method, and the concentration of 1-butene in the n-butene obtained here is usually 20 to 60%. Therefore, in the case of the MEK synthesis method using an oxygen complex in the case of the once-through method, since 2-butene hardly reacts, the MEK synthesis method for n-butene is
The yield of K does not exceed 60%.

Therefore, in the present invention, in order to separate the mixture of 1-butene and 2-butene obtained by the above steps,
A 2-butene separation column 7 is installed, and only the separated 1-butene is led to the oxidation reaction column 14 via a line 8.
At this time, the removed 2-butene is transferred from line 9 to dehydration tower 2.
1. It is led to an isomerization reaction tower 23 through a heating tank 22, a part of which is converted into 1-butene, and then a heavy fraction separation tower 24
After separating the heavy fraction 25, the amount of 1-butene is increased by returning it to the upstream of the 2-butene separator 7 through line 6, and the amount of n-butene in the raw material C4 fraction is increased. The same amount of 1-butene is introduced into the oxidation reaction step of 10 or less of the oxygen absorption towers. Thereby, the MEK yield per n-butene can be 95% or more.

As the 2-butene separation device 7, a distillation column that utilizes the boiling point difference between -butene and 2-butene is used. Distillation separation is carried out at an operating temperature of 70° C. or less and a pressure of 5 kg/ctag or less. In the isomerization reaction column 23, 10 to 20% of 2-butene is converted to 1-butene. The isomerization reaction uses a silica-alumina catalyst at a reaction temperature of 20
It is carried out under conditions of 0 to 350°C and a pressure of 5 to 1 Qatm.

Inside the oxidation reaction tower (MEK synthesis tower) 14, a portion of water was added to palladium chloride (PdC12), cuprous chloride (CuC4), hexamethylphosphoramide (HMPA), and benzonitrile (PHCN). Catalysts II & 12 are supplied to the catalyst liquid in an oxygen absorption tower 10 that absorbs air (oxygen) 11 to form an oxygen complex.
Almost 100% butene and a few % 2-butene reacted to ME
It becomes K. This reaction is carried out at a relatively low temperature (40 to 80° C.) and low pressure (normal pressure to 30 atmospheres), and since it is a liquid phase reaction and an exothermic reaction, it is usually equipped with a stirrer and a cooling device. Note that although the illustrated reactor is one stage, a multistage reactor may be employed. The catalyst liquid containing MEK as a reaction product is led to the catalyst separation column 15, where crude MEK is taken out from the top of the tower and catalyst liquid is taken out from the bottom of the tower. The catalyst liquid from the bottom of the column is recycled via line 12 to the absorption column IO. On the other hand, crude ME from the top of the tower
K is introduced into a butene separation column 16 where C4 fractions such as radical 2-butenes and other butanes are removed from the top and M
EK and water are removed from the bottom of the column.

The MEK-containing water from the bottom of the column passes through line 17 to remove moisture in the MEK ellipse device 18, butyraldehyde and moisture (line 19) are removed from the top of the column, and the MEK product passes from the bottom to line 20. can get. On the other hand, the group C4 fraction from the top of the butene separation column 16 is returned to the oxygen absorption column 10 via line 8.12.

The material balance of the process according to the present invention and a comparative process in which an isomerization device is installed downstream of the reaction system are shown in FIGS. 2 and 3. For ease of comparison, n~butene in the raw material is shown as 100 (breakdown: 1-butene 40%, 2-butene 60%), isomerization equilibrium 1-butene concentration is 13%, and trace components are shown as O.

As is clear from the figure, in the process of the present invention, compared to the process shown in FIG. (for example, 560 to 100 for oxidation reaction towers, 550 to 10 for catalyst separation towers and butene separation towers), the capacity of the equipment can be reduced, and the amount of steam can be reduced to about 3
0%, and power consumption is reduced by approximately 40%. (2) The pressure in the oxidation reaction tower 14 required to obtain the 1-butene partial pressure required for the oxidation reaction can be reduced to about 115, and the weight of the oxidation reaction tower can be reduced. (3) In relation to (2), with pressure reduction, the production of by-products such as aldehydes and chlorides, as well as the production of polymers of raw material butene, can be suppressed, improving the selectivity of MEK production, That is, the MEK yield can be improved. Therefore, the amount of raw materials supplied required to obtain the same amount of MEK can be reduced.

Next, Table 1 shows an example of specific comparison results of utilities in the processes shown in FIGS. 2 and 3. In the process of the present invention, although the 2-butene separation column 7 is installed in the raw material pretreatment step, a large utility reduction effect can be obtained compared to the comparative process.

Table 1 In the above examples, the 2-butene separation column 7 was shown as a distillation column, but other separation methods may also be used. The sulfur @ maple collection method, which separates sulfur by taking advantage of its tendency to dissolve in water, is also effective, and similar effects can be obtained.

(Effect of the invention) By implementing the present invention, the following effects can be obtained.

(1) The yield of n-butene-based MEK can be improved to, for example, 95% or more, and therefore the raw energy cost can be reduced by about 30% and the equipment cost by about 5%.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a process flow of a MEKti manufacturing apparatus showing an embodiment of the present invention, and FIG. 2 is a diagram illustrating the material balance of the present apparatus. 1... Raw material C4 fraction, 2... Butadiene separation device,
3... Butene line, 4... Isobutyne separation device,
5... Isobutyne line, 6... N-butene line, 7... 2-butene separation column, 8... 1-butene line, 9... 2-butene line, 10... Oxygen Absorption tower, 11... Air line, 12... Oxidation catalyst liquid line, 13... Exhaust line, 14... Oxidation reaction tower, 15
... Catalyst separation column, 16... Butene separation column, 17...
・Rough MEK line, 18...MEKii equipment, 19
...Butyraldehyde line, 20...Product MEK
Line, 21... Dehydration tower, 22... Heater, 23.
... Isomerization reaction column, 24... Heavy fraction separation column, 25...
・Heavy line.

Claims (1)

[Claims] (1) In a device that synthesizes methyl ethyl ketone by oxidizing 1-butene in the presence of a metal complex catalyst solution that activates oxygen by generating an oxygen complex, a device for separating 1-butene and 2-butene as a raw material pretreatment step. and 2-butene to 1
- An isomerization device for converting into butene.