JP3874470B2 - Methyl methacrylate production equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is arranged and anti応槽, solid-liquid continuously separated in the inclined channel and consists only of continuously separating device the liquid components, a device for the continuous separation wall portion of the reaction vessel The present invention relates to an apparatus for producing methyl methacrylate .
[0002]
[Prior art]
In the chemical industry, a reaction method using a solid catalyst slurry liquid of fine particles, for example, a reaction method such as a gas-liquid solid phase reaction or a liquid solid phase reaction is employed. Usually, the apparatus for this reaction system consists of a reaction tank for carrying out the reaction, and a separator for separating the catalyst slurry liquid and the reaction liquid.
[0003]
Meanwhile, in order to separate the gas-liquid solid phase goodness Ri liquid component, sedimentation, centrifugation, separation by filtration machines, and the like various methods.
However, in sedimentation separation, although it depends on the sedimentation rate of solids, usually a large area is required, and an increase in the size of the reaction apparatus is unavoidable. Centrifugal separation requires mechanical equipment, and includes sliding parts, Since there is a seal part, there is a problem of clogging there and mechanical catalyst destruction, etc., it may not be used in systems that handle high pressure systems or hazardous materials, and filter separation and filter clogging and scaling may not be possible. This raises the problem that the filtration speed is lowered, the back washing needs to be performed frequently, and stable continuous operation is not possible.
[0004]
For example, as a gas-liquid solid phase reaction example, a catalyst in which palladium or the like is supported on a carrier such as silica, alumina, diatomaceous earth, activated carbon or zeolite, and methacrolein as an aldehyde and methanol as an alcohol are suspended. A method for producing a carboxylic acid ester (methyl methacrylate) in which molecular oxygen-containing gas is blown to cause liquid phase oxidation of aldehyde (methacrolein) and esterification at the same time is known (for example, Japanese Examined Patent Publication No. 45-34368). JP-B-57-35858, JP-B-57-35859, JP-B-61-60820, JP-B-62-7902, etc.).
[0005]
[Problems to be solved by the invention]
The present invention provides a reaction apparatus that solves various problems of the above-mentioned ordinary reaction apparatus. For example, in the chemical reaction shown in the above-mentioned gas-liquid solid reaction example, in the presence of a catalyst. As a side reaction, isobutyraldehyde, methyl isobutyrate, and the like are generated as a side reaction in a low oxygen concentration region. These by-products are substances that inhibit the polymerization reaction when the main reaction product is polymerized to produce a polymer, and thus purification and separation must be sufficiently performed. That is, when the selectivity of these by-products increases, the refining equipment becomes larger and the refining energy also increases. Moreover, the loss of the raw material by the fall of the selectivity of a main reaction component and a large sized esterification reactor are needed. For this reason, the selectivity of isobutyraldehyde and isobutyric acid methyl ester must be suppressed as much as possible. In order to suppress the side reaction, it is necessary to reduce the volume of the portion existing in a state where the gas (oxygen) is separated or shorten the residence time in the separation portion (increase the flow rate of the liquid).
[0006]
In order to solve this problem, the present inventors initially provided a multistage inclined plate as a separation device on the side surface of a cylindrical reaction tank as shown in FIG. 1, and the gas in the flow path 1 as shown in FIG. Due to the difference in specific gravity between the slurry liquid after ascending degassing and the liquid containing the gas in the reaction tank, a circulation flow path of the slurry liquid is formed in the flow path 1, and a part thereof (substantially equal to the amount of liquid supplied into the reactor) Amount) was allowed to flow into the inclined plate, the solid liquid was settled and separated, and the liquid components were separated.
However, due to the pressure difference between the upper and lower portions of the flow path 1 caused by the liquid flow as shown in FIG. 3 and the density difference due to the catalyst settling in the inclined plate, the circulation of the liquid in the inclined plate occurs. The flow in the inclined plate became a turbulent region, and the separated solid catalyst was wound up again, so that the separation was impossible.
[0007]
[Means for Solving the Problems]
Accordingly, the present inventors in order to solve the above problems, the results of extensive studies on a multi-stage inclined channel provided adjacent to the mixture circulation channel arranged on the side wall of the reaction vessel, inclined channel suitable aperture In the flow path to make the flow in the flow path laminar, thereby separating the reaction liquid components in the flow path, placing the settled particles on the mixture circulation flow path, and continuously inside the reaction tank The present invention has been found to be able to be restored, and the present invention has been completed.
[0008]
That is, the present invention is a reaction vessel in which a catalyst, methacrolein, and methanol are suspended, and molecular oxygen-containing gas is blown into this to cause liquid phase oxidation of methacrolein and at the same time an esterification reaction is performed to obtain methyl methacrylate. And a separation device for continuously separating the methyl methacrylate liquid component from the gas-liquid solid mixture after the reaction , and a mixture introduction area and a mixture discharge area at the peripheral wall of the reaction tank. A mixture circulation channel is provided, and in the upper mixture introduction area of the circulation channel, the channel is widened so that the gas rising speed is larger than the liquid descending flow rate, and the gaseous oxygen-containing gas is separated from the solid liquid. with the possible adjacent the multistage flow path having a constant inclination with respect to the circulation flow passage, provided the appropriate aperture to the said inclined channel, the layer flow liquid-solid mixture in the flow channel Basin and Continuous precipitated a solid catalyst by Rukoto, separating the liquid component comprising methyl methacrylate from the inclined channel, and was set to continuously circulate inside the reaction vessel of a solid catalyst placed on a circulation flow path An apparatus for producing methyl methacrylate, comprising a separation device .
[0009]
The present invention will be described in more detail.
The present invention is a reaction apparatus comprising a reaction vessel and a device for continuously separating liquid components from a gas-liquid solid mixture or liquid-solid mixture. As shown in FIG. 1, (A) is a gas-liquid solid solution in the reaction vessel. an example of a case of performing phase reaction, a reactor in which to place the separating device is provided in the peripheral wall portion of the anti応槽, the apparatus may be provided over the entire circumference of the reactor as shown in FIG. 1 (a), it may be provided in a part of or the peripheral wall portion.
First, the flow of the liquid will be described with reference to FIG. The reaction liquid (slurry liquid) continuously supplied from the inside of the reaction tank to the circulation flow path 1 through the introduction area passes through the circulation flow path 1 and returns to the inside of the reaction tank through the discharge area.
[0010]
When the reaction system is a gas-liquid solid reaction system ((A) in FIG. 1), the flow rate in the region can be reduced by making the introduction region of the flow channel 1 have a relatively large cross-sectional area. The gas rises easily in the zone and is degassed . If the falling speed of the mixed compounds smaller than the gas rise velocity gas rising gas degassed channel will not be mixed.
[0011]
When the reaction liquid (slurry liquid) in the reaction tank flows down the circulation flow path 1, a part of the flow continuously flows into the multi-stage inclined flow path, and the flow of the inflow liquid forms a laminar flow region. The speed of the liquid flowing in the inclined flow path is determined by the cross-sectional area of the flow path and the amount of the reaction liquid flowing out from the reaction device (approximately the same amount as the amount of the reaction liquid to be supplied). As shown in FIG. 2, the solid particles settled in the inclined channel slide down on the inclined plate, ride on the circulation channel 1 and return to the apparatus, and the separated reaction liquid rises in the inclined channel and overflows the area. Escaping and overflowing.
[0012]
More specifically, first, as shown in FIG. 4, the shape of the inclined flow path forming the solid separation zone is such that solid phase components in the solid-liquid mixture (slurry liquid), for example, catalyst particles are not deposited. It is necessary to make the inclination angle θ have an inclination angle greater than the repose angle. When the solid in the solid-liquid mixture has a higher specific gravity than the liquid, it is in the range of 90 ° to 0 ° and is greater than the angle of repose of the solid. It is in the range of 0 ° to −90 ° and is greater than (or less than) the angle of repose of the solid. That is, in the present invention, the inclination angle of the inclined plate forming the inclined flow path is in the range of 90 ° to −90 °, and the solid does not stay in the flow path.
Specifically, when the specific gravity of the solid is heavier than that of the liquid, the range is, for example, 45 ° to 85 °, preferably 50 ° to 80 °, and more preferably 60 ° to 75 °. If the angle is large, the solid sedimentation speed increases, but if the angle is too large, the separation apparatus becomes large, and therefore the angle is appropriately selected as necessary. As a result, a fluid state can be secured without retaining the solid phase component, for example, the catalyst.
[0013]
In order to increase the sedimentation rate of the catalyst itself, it is desirable to increase the particle size and density of the catalyst particles and increase the sedimentation rate as much as possible in order to shorten the separation time and suppress side reactions. If it is too large, the specific surface area of the catalyst will be small and the reaction rate may be reduced. If the density is too large, the power required for uniform dispersion in the reactor will increase, so an appropriate size is selected.
The vertical cross-sectional shape of the inclined channel with respect to the channel direction may be an elongated rectangular structure formed of parallel plates, for example, a tube structure as shown in FIG. 5 or a honeycomb structure.
[0014]
Next, when the object is a gas-liquid solid mixture, the gas is first separated from the solid-liquid at the upper part of the circulation channel 1 so that the channel is widened so that the gas rising speed becomes larger than the liquid descending flow rate. to width, it is preferable to funnel-shaped as shown in the introduction zone of Figure 2 if e example. When bubbles are entrained in the inclined flow path, solids (catalyst) are entrained, which may hinder settling and separation of solids. However, mixing of a small amount of bubbles is not particularly problematic as long as it does not hinder.
[0015]
Next, the flow rate of the liquid that descends in the circulation channel 1 is not particularly limited. However, since the catalyst in the reaction system as described above undergoes alteration and side reaction of the catalyst in a state away from the environment of the reaction field, the residence time is shortened as much as possible in the circulation channel 1 from which the gas is separated. That is, it is preferable to pass through as fast as possible.
In addition, the vertical channel width of the inclined channel is preferably as narrow as possible in order to reduce the time required for sedimentation of the solid. However, it is necessary to set the width to an appropriate width due to clogging of the solid and processing limitations of the apparatus. These values are determined by the specific gravity of each solid-liquid, the particle size of the solid, the liquidity (viscosity, etc.), etc.
[0016]
The liquid flow in the inclined channel must be a laminar flow area, and the flow velocity of this part is determined by the amount of extraction from the reactor and the cross-sectional area of all stages of the inclined plate channel (strictly speaking, the flow rate of each channel) The flow rate is determined by the pressure difference, density difference and flow resistance described below), the size of the reaction device, the outflow amount of the reaction liquid, and the like, and the size of the inclined flow channel and the number of inclined flow channel stages are determined.
The pressure difference between the pressure at the inlet of the inclined channel due to the flow of the liquid in the channel 1 (a pressure difference occurs between the upper and lower parts of the channel) and the pressure at the outlet of the inclined channel, and the solid (catalyst) in the inclined channel. Due to the difference in density between the mixture near the inlet of the channel and the liquid component near the outlet in the inclined channel when settling, the overflow flow is distributed to the flow velocity flowing between the inclined channels.
[0017]
Here, in the case of providing the inclined channel two or more stages in a vertical direction, the separator is not provided Rio down only inclined channel is each inclined passage by the pressure difference and the density difference at equal flow rates not flow, not good separation of the solid-liquid for circulation of liquid takes place in a plurality of inclined channel, and aperture to set up giving the pressure loss in the inclined channel, whereby a certain degree evenly flow that the liquid Is possible.
Here, Rino shape grain gives the pressure loss is not particularly limited, for example, may be a shape as shown in FIG. 6, the opening ratio need not be uniform, for example, toward the lower side is the upper side The aperture degree may be appropriately changed, for example, by reducing the aperture ratio.
[0018]
The solid (catalyst) settled and separated in the inclined channel flows along the inclined plate and is accompanied by the mixed liquid passing through the channel 1 and continuously returns to the inside of the apparatus.
Preferably, at the discharge port of the flow channel 1, taking a certain distance from the lowermost part of the inclined plate suppresses an increase in the flow velocity in the inclined flow channel near the lowest stage due to a pressure increase due to a change in the flow channel. Can do. In addition, one or several baffle plates are provided in the discharge area of the flow path 1, thereby suppressing the inflow of bubbles from the lower part of the flow path 1 to the separation portion.
As described above, in the separator of the reactor of the present invention, since as it can be separated only gas-liquid-solid reaction system or al-liquid component extraction, the catalyst is a solid is separated from the reaction solution, continuously Returned to reactor.
[0019]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
Example 1
Production of methyl methacrylate by continuous oxidative ester reaction in the presence of oxygen using methacrolein as raw material aldehyde and methanol as alcohol was carried out under the following reaction conditions.
[0020]
The apparatus used was reacted using a stainless steel reactor equipped with a stirrer having an inner diameter of 133 mm and an internal volume of 5.5 liters. The reactor includes a reflux condenser, a liquid feed port, a liquid discharge port, and a gas introduction port, and is stirred by a stirrer. The reaction temperature was measured with a thermometer inserted inside, and the temperature was adjusted with a hot water jacket.
Moreover, the liquid level in the apparatus was adjusted by adjusting the height of the overflow part from the apparatus connected to the reaction solution outlet pipe.
The reaction solution from the reactor was supplied to the inclined channel, and solid-liquid separation was performed to extract the reaction solution. Here, the inclination angle of the inclined channel is set to 60 degrees upward in the flow direction with respect to the horizontal plane, the shape of the inclined channel is set to 20 mm vertically and 20 mm horizontally to the liquid flow direction, and the channel is divided into four in the vertical direction. A throttle was provided at each inclined channel outlet, and the aperture ratio was 3.7%.
[0021]
A reactor was charged with 1 kg of a catalyst in which 5.0% by weight of palladium, 3.3% by weight of lead, 4.0% by weight of magnesium, and 4.5% by weight of aluminum were loaded on silica gel, and the temperature was 80 ° C. and the pressure was 4 kg / cm ^2. The test was performed under the following three conditions under the gauge conditions.
(1) A 35% methacrolein / methanol solution was supplied to the reactor at 0.8 liter / Hr, and the reaction was carried out while aeration of air and N ₂ at 1034 N liter / Hr. The addition amount of NaOH was adjusted so that the pH of the reaction solution was kept at 5-7.
(2) The reaction was performed while supplying 2.1 liter / Hr of methacrolein / methanol solution having the same concentration as in (1) to the reactor and ventilating air + N ₂ at 1038 Nl / Hr. The addition amount of NaOH was adjusted so that the pH of the reaction solution was kept at 5-7.
[0022]
(3) The reaction was performed while supplying 4.3 liter / Hr of methacrolein / methanol solution having the same concentration as in (1) to the reactor and venting air + N ₂ at 1044 N liter / Hr. The addition amount of NaOH was adjusted so that the pH of the reaction solution was kept at 5-7.
As a result, when the reactor internal liquid and the inclined channel outlet liquid were analyzed and compared, there was no difference in the concentration of by-products under all three conditions.
Here, as a result of stopping the supply of air at a certain point in time and performing the reaction under anoxic reaction conditions, the concentration of isobutyraldehyde and isobutyric acid methyl ester, which are by-products, rapidly increases and catalyst alteration occurs. I know you will.
This indicates that by using the reaction apparatus of the present invention to achieve rapid catalyst separation in the oxygen-free region after gas-liquid separation, no by-product was produced.
[0023]
(Example 2)
Using the same raw materials and equipment as in Example 1, the reaction was carried out under the following reaction conditions.
A reactor was charged with 1 kg of a catalyst in which 2.5% by weight of palladium, 5.0% by weight of lead and 2.0% by weight of magnesium were supported on γ-alumina, and the reactor was subjected to the same conditions as in (3) of Example 1. The reaction was carried out in methacrolein / methanol solution, air + N ₂ , temperature and pressure. The amount of NaOH was adjusted so that the pH of the reaction solution was kept at 5-7.
As a result, the reactor main body liquid and the inclined channel outlet liquid were analyzed and compared, and no difference in by-product concentration was found.
In addition, it has been found that, in the catalyst in this reaction, a rapid increase of by-products similar to that in Example 1 and alteration of the catalyst are observed under the oxygen-free reaction conditions.
This indicates that by using the apparatus of the present invention, rapid catalyst separation was achieved in the oxygen-free region after gas-liquid separation, and no by-product was produced.
[0024]
【The invention's effect】
According to the present invention, the catalyst, methacrolein, and methanol are suspended, and this is suspended in molecular oxygen.
Blowing in gas and liquid-phase oxidation of methacrolein at the same time as the esterification reaction can be performed to improve the reaction yield by preventing side reaction products when producing methyl methacrylate and prevent deterioration of the catalyst It became. Further, when operating the device does not require power, etc., requires no fine adjusted, it is possible to provide a that equipment obtained stably continuously separated.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing an embodiment of the present invention, in which (A) is a tank (bubble column ) in which a separation device is installed in a gas-liquid solid system.
FIG. 2 is a diagram showing the separation device of FIG. 1 and the flow of the gas-solid liquid thereof.
FIG. 3 is a diagram showing a flow distribution in the inclined flow path caused by a static pressure difference generated by a flow pressure loss in the circulation flow path 1 and a density difference generated when a catalyst settles in the inclined flow path.
FIG. 4 is a diagram showing an inclination angle in an inclined channel.
5 is a cross-sectional view perpendicular to the inclined channel of partial release device parts.
6 is a diagram illustrating a grain Rino shape provided inclined channel.
[Explanation of symbols]
1: Circulation channel

Claims (1)

A catalyst, methacrolein, and methanol are suspended, and molecular oxygen-containing gas is blown into the catalyst to liquid-phase oxidize methacrolein, and at the same time, an esterification reaction is carried out to form a methyl methacrylate and a post-reaction gas-liquid. A methyl methacrylate production apparatus comprising a separation apparatus for continuously separating a methyl methacrylate liquid component from a solid mixture , wherein a mixture circulation channel having a mixture introduction area and a mixture discharge area is provided on a peripheral wall portion of the reaction tank. And the width of the upper mixture introduction area of the circulation channel is widened so that the rising speed of the gas is larger than the descending flow rate of the liquid so that the gaseous oxygen-containing gas can be separated from the solid liquid, and the multi-stage flow path having a constant inclination with respect to the circulation flow passage adjacent, provided appropriate aperture to the said inclined channel, solid by the flow of the liquid-solid mixture in the flow channel and laminar flow Allowed to settle catalyst, arranged continuous separation device the liquid components were separated, and was set to continuously circulate inside the reaction vessel of a solid catalyst placed on a circulation passage comprising a methyl methacrylate from the inclined channel An apparatus for producing methyl methacrylate .

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