JPH04169553A - Production of sec-butyl acetate - Google Patents

Abstract

PURPOSE:To advantageously obtain the title compound by feeding acetic acid and linear butene both in a liquid state to a specific catalytic layer of a continuous circulation type fixed bed reactor in a counter flow under a specific condition and recycling the reaction mixture to the catalytic layer at a specific temperature at a specific ratio. CONSTITUTION:A continuous circulation type fixed bed reactor 2 having a catalytic layer 3 packed with a styrene-based (and/or phenol)sulfonic acid type ion exchange resin catalyst wherein an inlet temperature of the catalytic layer is maintained at 80-120 deg.C is charged with acetic acid and linear butene both in a liquid state in a counter flow under conditions of a molar ratio A of acetic acid/linear butene in a feed flow 1 of 1.0-2.0 and LHSV based on the catalytic layer 3 of acetic acid of 0.1-1.0 and the prepared reaction mixture is cooled to >=70 deg.C, is circulated through an inlet of circulation flow 4 to the catalytic layer 3 in a ratio shown by the formula (X is weight ratio of circulation flow rate/feed flow rate) to give the title compound useful as a solvent, perfume, etc., by using an inexpensive reactor by a liquid-phase reaction efficiently and in readily temperature control in a reaction zone, in high linear butene conversion ratio and high productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a process for the continuous production of sec-butyl acetate by adding linear butene to acetic acid in the presence of an acidic ion exchange resin catalyst. sec-Butyl acetate produced according to the present invention is a substance useful as a solvent, a fragrance, and the like.

[Issues to be solved by the prior art and the invention]
It is well known that when acetic acid and linear butenes 1-butene or 2-butene are reacted with an acidic ion-exchange resin catalyst, sec-butyl acetate can be obtained as shown in the following formula (Japanese Patent Laid-Open No. 49-1999). -100016 Publication, Japanese Unexamined Patent Publication No. 5
5-102530).

(:) lscOOH+ CI(2=CH-CH2-CH
3→CH3CO0C! ((CH3)CH2-CH3C)
13(:00H+ CH3-(:)I-CH-CH3
→CH3CO0CH(CH3)(:H2-CH3 The above esterification reaction is known to be a liquid phase reaction, a gas phase reaction, and a gas-liquid mixed phase reaction, but in the gas phase reaction, linear butene is polymerized on a catalyst. This is unavoidable, and this has the disadvantage of shortening the catalyst life, which is undesirable from an industrial perspective.Also, in a gas-liquid co-current multiphase reaction of liquid acetic acid and gaseous linear butene, liquid acetic acid tends to form on the catalyst surface. catalytic efficiency is increased, and as a result it becomes possible to use mild reaction conditions.

However, when gaseous linear butene passes through the catalyst layer, there is an unavoidable disadvantage that the contact efficiency in that part inevitably decreases. Furthermore, in the case of this gas-liquid multiphase reaction, the linear butene that actually reacts is thought to be the linear butene dissolved in acetic acid, and when the linear butene in the liquid phase is consumed by the esterification reaction, it becomes a gas. It is necessary for the linear butenes to dissolve back into the liquid phase, which takes time.

Therefore, a liquid phase reaction in which both linear butene and acetic acid are reacted in a liquid phase is an industrially preferred reaction.

Regarding the reaction method of the above-mentioned esterification reaction, a continuous method is industrially more advantageous than a batch method. In the case of continuous type reactors, there are continuous seed reactors, fixed bed flow reactors, moving bed reactors, fluidized bed reactors, etc., but when considering the cost and maintenance of the equipment, fixed bed continuous pipes are preferable. A type reactor is most preferred, or when attempting to industrialize the above reaction using a fixed bed continuous tubular reactor, since the above reaction is a large exothermic reaction, it is inevitably accompanied by an increase in temperature in the flow direction.

As a result, the rate of the reverse reaction in which the generated sec-butyl acetate decomposes into acetic acid and linear butene increases, and the conventional method not only fails to increase the final conversion rate of linear butene, but also causes a significant temperature rise. It has been found that in some cases the catalyst loses its activity.

Therefore, in order to ensure high linear butene conversion and catalytic activity, it is necessary to appropriately manage and control the temperature distribution within the reaction zone.

Therefore, in order to realize the above-mentioned esterification reaction using a single-tube fixed bed reactor, which is advantageous in terms of use and maintenance, there is a strong need for the development of an inexpensive and easy reaction temperature control method.

[Means for Solving the Problems] That is, the present invention provides a method in which the molar ratio of acetic acid to linear butene in the feed stream is in the range of 1.0 to 2.0, and the LHSV of acetic acid to the catalyst layer is in the range of 0.1 to 2.0. 10, continuous flow with the inlet temperature of the catalyst layer filled with a styrene sulfonic acid type ion exchange resin catalyst and/or a phenolsulfonic acid type ion exchange resin catalyst maintained in the temperature range of 80°C to 120°C. Both acetic acid and linear butene are supplied in liquid form and in parallel flow to a fixed bed reactor, the resulting reaction mixture is cooled to a temperature not lower than 80°C, and the The present invention relates to a method for producing sec-butyl acetate, which is characterized by circulating it through a catalyst bed.

7.6 A + 5.9 where X indicates the circulation ratio, defined as the weight times the circulation flow rate over the feed flow rate, and A indicates the molar ratio of acetic acid to linear butenes in the feed stream.

The present invention will be further explained below.

The acidic ion exchange resin referred to in the present invention is an ion exchange resin exhibiting acidity, and is a styrene sulfonic acid type resin or a phenol sulfonic acid type resin. Styrenic sulfonic acid type ion exchange resin is a sulfonated resin obtained by copolymerizing styrene and a polyunsaturated compound such as divinylbenzene. Furthermore, the phenolsulfonic acid type ion exchange resin is usually a product obtained by condensing phenolsulfonic acid with formaldehyde.

Moreover, linear butene refers to 1-butene or 2-butene, and either of them can be used in the same manner. Here, when we simply refer to linear butene, we mean both of them.

As a source of linear butene used in the present invention, a hydrocarbon mixture containing about 20% by weight or more of linear butene can be used. The so-called spent-spent BB is a C4 fraction containing linear butenes obtained by
The distillate is valid. In the method of the present invention, in order to suppress heat generation due to the reaction, the above-mentioned spent-spent BB
It is preferable to use a fraction (sometimes referred to herein as rS/S butene).

In addition to hydrocarbons having 4 carbon atoms such as linear butene and butane, this S/S butene also contains trace amounts of olefins and diolefins having other than 4 carbon atoms. Therefore, there is a concern that olefins having carbon atoms other than 4 may react with acetic acid to generate impurities that may inhibit the purification of acetic acid as an unreacted raw material or sec-butyl acetate as a product.

However, as explained by the examples below,
These disadvantages do not occur in the present invention.

The acetic acid/linear butene molar ratio in the feed stream of fresh raw material to the catalyst bed (hereinafter simply referred to as "feed stream") is between 1.0 and 2.0, more preferably between 1.2 and 2. ,0. If the molar ratio is less than 1.0, side reactions such as polymerization of linear butenes will increase, which is economically unfavorable. Also, the molar ratio is 2
．． If it is larger than 0, the amount of unreacted acetic acid is large, which increases the burden of recovery such as distillation, which is not preferable. Linear butene and acetic acid can be fed to the reactor separately or in a mixture as long as the above molar ratio is maintained. Note that the above-mentioned supply flow refers to a flow that does not include the circulation flow described below. Therefore, the acetic acid and linear butene in the above molar ratio do not contain components derived from the circulating flow described below.

The supply flow rate to the catalyst layer is the LH of acetic acid to the catalyst layer.
SV is preferably 0.1 to 10, more preferably 0
．． It is in the range of 2-5. If LHSV is less than 0.1, the production efficiency will be too low, which is not preferable.

On the other hand, if it is larger than 10, the average residence time in the catalyst layer necessary for the reaction cannot be ensured and the conversion rate becomes low, which is not preferable.

The reaction pressure in the reactor in the present invention may be a pressure sufficient to maintain the reaction system in a liquid phase, for example, 5 Kg/cm2 to
100 Kg7cm2, preferably 5 to g/crn2
It can be appropriately selected from the range of 50 g/cm2 to 50 g/cm2. When the reaction pressure is lower than 5 Kg/cm2, a gas phase portion is generated, which is not preferable. In addition, the reaction pressure is 100 Kg/cm2
If the pressure is higher, equipment with extremely high pressure resistance must be provided, which is economically unfavorable.

The reaction targeted by the present invention is an exothermic reaction, but in order to realize this in a flow-type fixed bed reactor that does not cause yellowing, the present inventors have realized that temperature control within the reaction zone is important. I found a new idea and established a method.

That is, the reaction temperature near the inlet of the catalyst layer in the reactor needs to be 80 to 120°C.

As mentioned above, the reaction of the present invention is an exothermic reaction, but since the above temperature indicates the temperature near the inlet of the catalyst layer, in order to maintain the temperature within the above range, heating must be carried out as appropriate, taking into account the presence of circulation flow. Alternatively, this can be easily achieved by cooling. If the temperature near the inlet of the catalyst layer is lower than 80° C., the reaction rate will be too slow even if the subsequent temperature of the catalyst layer is high, which is not preferable. Also, if the temperature is higher than 120℃, vinegar @sec
The rate of the reverse reaction in which -butyl decomposes into acetic acid and linear butene increases, which not only makes it impossible to increase the conversion rate of linear butene, but also increases side reactions such as polymerization of linear butene, which is undesirable.

In the present invention, a specific amount of at least a part of the reaction mixture, which is a reaction product that has passed through the catalyst bed, is circulated to the catalyst bed through an appropriate heat removal equipment such as a heat exchanger, so that It is important to control the temperature. During the circulation, unreacted substances or the desired sec-butyl acetate are circulated without being particularly separated from the reaction product flowing out from the reactor.

The temperature of the circulating flow that is circulated to the catalyst bed via appropriate heat removal equipment is naturally lower than the temperature of the reaction product at the outlet of the catalyst bed because it is circulated after being cooled. The temperature does not fall below the temperature near the inlet, i.e. 8
Cool to a temperature not below 0°C. If the catalyst is cooled to a temperature lower than 80° C. and circulated, the temperature of the catalyst layer into which the circulating flow is introduced becomes too low, which is not preferable. More preferably, the temperature is approximately the same as the reaction temperature in the catalyst layer portion to be introduced.

The circulation flow rate required for the reaction temperature control of the present invention varies depending on the amount of heat generated within the reaction region, the allowable temperature rise range, the amount of heat dissipated to the outside of the reaction region, and the like. Additionally, the amount of heat generated within this reaction zone varies depending on the molar ratio of acetic acid to linear butene in the feed stream and the feed flow rate.

As a result of intensive research into these complex factors, the present inventors have determined that the circulation ratio The present invention has been completed based on the discovery that appropriate temperature control is possible when the molar ratio A to the molten metal is equal to or higher than the value expressed by the above formula (I) as a variable.

In particular, it is unexpected that in the reaction of the invention the circulation factor can be defined solely by the molar ratio A of acetic acid to linear butene in the feed stream.

There is no particular limit to the upper limit of the circulation number, and a circulation amount greater than necessary increases the burden on equipment, energy, etc. required for circulation, which is undesirable, and is practically 100 times or less.

In the present invention, there is no particular restriction on the position of the catalyst layer where the circulating flow is introduced. For example, as shown in FIG. 1, the recycle stream may be circulated at a location where it joins the feed stream at the reactor inlet.

However, in order to effectively exert the temperature control effect of the circulating flow, it is also possible to circulate the circulating flow to a position in the middle of the catalyst layer, as shown in FIG. 2, for example. However, in this case, assuming that the volume of the catalyst bed from the position where the circulating flow is introduced to the outlet of the catalyst bed is 2, the position is preferably such that 2 is one-tenth or more of the total volume of the catalyst bed. If it is introduced at the rear of this position, the circulating flow will not be sufficiently dispersed within the catalyst layer.
This is not suitable because stable temperature control becomes difficult.

Although the method of the present invention has been described using a single stage reactor, it may also be a reactor having two or more stages arranged in series as long as the above-mentioned conditions are met.

In the case of multiple reactors in series, both the feed stream and the temperature near the catalyst bed inlet refer to the temperature in the first reactor where the reaction initially occurs, and also to the temperature at which the circulating stream should be circulated. The catalyst bed volume in the position description means the total volume of the catalyst beds in a plurality of reactors.

In addition, by appropriately extracting from the reaction mixture and distilling it, the target product, sec-butyl acetate, of high purity can be easily obtained.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. The composition of the S/S butene used in this example is linear butene 6
4.3% by weight, butane 35.2% by weight. In addition, the molar ratio refers to the molar ratio of acetic acid to linear butene, and L
HSV is based on the amount of acetic acid supplied.

In the center of a stainless steel cylindrical tube with a length of 2+A and an inner diameter of 10 cm, a catalyst was placed in the center of a stainless steel cylindrical tube with Rewacit 5P0118 (H- The reactor was filled with 10 liters of mold (trade name), and the remaining space was filled with porcelain Raschig rings to form a fixed bed continuous tubular reactor. This reactor was placed vertically in a constant temperature bath maintained at 85°C, and
The device shown in the figure was constructed. A constant temperature bath is not shown.

That is, a liquid feed stream 1 consisting of acetic acid and linear butenes is fed to a reactor 2 and reacts in a catalyst bed 3, and the reaction mixture is withdrawn via a circulation pump. The reaction mixture is cooled via a heat exchanger, a portion of which is cooled through the circulation flow inlet 4.
is circulated. The circulating flow joins the feed stream 1 at the circulating flow inlet 4 .

Moreover, the reaction mixture is continuously extracted from the reaction mixture outlet 5.

Acetic acid was added to this reactor at LHSV1. A feed stream with a molar ratio of 1,8 of O and linear butenes (99% purity by weight) was flowed at a reaction pressure of 20 g/cm2. The circulating stream was cooled to 85° C. via a heat exchanger, circulated at a circulation factor of 15 (calculated circulation factor calculated from the above formula (I): 1.5), and introduced from the inlet of the catalyst bed. At this time, the temperature distribution within the catalyst layer was increasing monotonically, and the temperatures at the inlet and outlet of the catalyst layer were 85° C. and 89° C., respectively.

The effluent reaction mixture was analyzed by gas chromatography every 5 hours, and under steady state conditions with stable composition, the conversion of linear butene was 86.2 mol%, and the selectivity to sec-butyl acetate was 94.3 mol%. There is, t,oo.

Even after continuous operation for hours, the activity of the catalyst hardly changed, and similar conversion rates and selectivities were obtained.

In the apparatus of Example 1, the catalyst was Amberlyst-15 (H type, Product name), S/S
The reaction was carried out in the same manner as in Example 1, except that butene was used as a linear butene raw material, and the catalyst bed inlet temperature, molar ratio, LH5V, reaction pressure, and circulation ratio were changed.

The results obtained are shown in Table 1. No decrease in catalyst activity was observed in either case.

Table 1 Example 2 3 4 5 Reaction pressure (Kg/cm2) 50 25 :l
IO50L HS V O,22,010,0
5,0 molar ratio 1.0 2.0 2.0
1.5 Constant temperature measurement temperature (”C) 80 90 10
0 120 calculation circulation multiple (7.3 1.3 1.
3 1.9 circulation multiple 2 (7.0 4.2 3
, 4 10.0 Examples 6 and 7 The reaction was carried out in the same manner as in Example 3, except that an apparatus as shown in FIG. 2 was used in which the position at which the circulating flow was introduced into the catalyst bed was changed.

Note that a constant temperature bath is not shown.

That is, in FIG. 2, a liquid feed stream 1 consisting of acetic acid and linear butenes is fed to a reactor 2, reacts in a catalyst bed 3, and the reaction mixture is withdrawn via a circulation pump.

The reaction mixture is cooled through a heat exchanger, and a portion of the reaction mixture is introduced into the catalyst bed 3 as a recycle stream through a recycle flow inlet 4 located in the middle of the catalyst bed 3 . Moreover, the reaction mixture is continuously extracted from the reaction mixture outlet 5.

The results obtained with the reactor shown in FIG. 2 are shown in Table 2. No decrease in catalyst activity was observed in either case.

Table 2 Example 67 Reaction pressure (g/cm2) 25 25L
HS V 2.0 2.0 Molar ratio 2.0 2.0 Constant temperature chamber part ("C) 90 90 Calculated circulation multiple
33 33 circulation multiple 4
．． 2 4.2 Circulation position 0.5
0.25 (Note) Circulation position: Shown as the value obtained by dividing the catalyst bed volume from the circulation flow introduction position to the catalyst bed exit by the total catalyst bed volume.

- Monwayu The reaction was carried out in the same manner as in Example 2 except that the reaction mixture was circulated without being circulated.

As a result, the temperature inside the catalyst layer rapidly increased, and the temperature at the outlet reached 180℃ or higher, and a large amount of sulfur dioxide gas was detected at the outlet of the reactor, so the reaction was stopped and the catalyst layer was examined. The catalyst, which was dark brown before the reaction, had turned black and had almost lost its acid activity.

Le! ”1λ above, l-? Reactions were carried out in the same manner as in Examples 4 and 5, except that the circulation ratio was changed.

The results obtained are shown in Table 3. In both cases, the catalyst lost its activity within several hours to several minutes.

Table 3 Comparative Example 23 Reaction pressure (g/cm2) 30 50L
HS V 10.0 5.0 Molar ratio 2.0 1.5 Constant temperature measurement (t) 100 120 Calculated circulation multiple 413 1.9 Circulation multiple
0.5 1. -0 [Effects of the Invention] The method of the present invention realizes an efficient liquid phase reaction in a fixed bed continuous tubular reactor that does not require equipment costs, and also allows easy control of temperature distribution within the reaction region. It has become possible to stably secure a high conversion rate of linear butene and high production efficiency of sec-butyl acetate. This also means that the mixed gas of linear butene and butane separated from the reaction mixture can be economically efficient even if it is disposed of as is, so it is necessary to recover, purify, pressurize, and reuse the linear butene. This has the effect of significantly reducing equipment costs.

In addition, as seen in the examples, the selectivity to sec-butyl acetate is sufficiently high, which not only reduces variable costs but also
Purification of 5eC-butyl acetate and unreacted acetic acid is also easy.

[Brief explanation of the drawing]

FIGS. 1 and 2 are process diagrams including reactors used in Examples. 1...Feed stream 2...Reactor 3...Catalyst layer 4...Circulating flow inlet 5...Reaction mixture outlet Patent applicant Nippon Petrochemical Co., Ltd.

Claims (2)

[Claims] (1) The molar ratio of acetic acid to linear butenes in the feed stream is 1.
．． LH in the range of 0 to 2.0 and for the acetic acid catalyst layer
Under conditions where the SV is 0.1 to 10, the inlet temperature of the catalyst bed filled with the styrene sulfonic acid type ion exchange resin catalyst and/or the phenolsulfonic acid type ion exchange resin catalyst is set at 80°C to 120°C. Acetic acid and linear butene were both fed in liquid form and in parallel flow to a continuous flow fixed bed reactor maintained at a temperature range, and the resulting reaction mixture was heated to 80°C.
A method for producing sec-butyl acetate, characterized in that the sec-butyl acetate is cooled to a temperature not lower than , and circulated through the catalyst layer at a rate represented by the following formula (I). (7.6A+5.9)/(3.6A^2+1.5A-1
)≦X(I) where X indicates the circulation ratio, defined as the weight multiple of the circulation flow rate to the feed flow rate, and A indicates the molar ratio of acetic acid to linear butenes in the feed stream. (2) The method according to claim 1, characterized in that, as the linear butene in the feed stream, a fraction obtained by removing butadiene and isobutylene from a C_4 fraction obtained by thermally decomposing naphtha is used.