JP2002179601A - Method for producing propylene chlorohydrin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for industrially advantageously producing propylene chlorohydrin at high objective selectivity and at high propylene availability by using a propylene-containing gas of any propylene content selected from a wide range. SOLUTION: The propylene chlorohydrin is obtained at high objective selectivity and at high propylene availability by using a composite reactor having a tubular reacting zone and a circular reacting zone forming circulating flow involving upflow and downflow at its downstream end, wherein, as the circular reacting zone a composite reactor to which a vapor-liquid separation zone is formed is used, supplying a chlorine-dissolved aqueous solution at the beginning end of the tubular reacting zone, supplying a propylene-containing gas on its downstream zone so as to react with each other, then completing the reaction in the cyclic reacting zone and discharging a purge gas and a product- containing aqueous solution from the vapor-liquid separation zone, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel process for producing propylene chlorohydrin from water, chlorine and propylene.

[0002]

2. Description of the Related Art Propylene Propylene chlorohydrin is an important compound as a raw material for producing propylene oxide.

[0003] The propylene chlorohydrin is generally produced by reacting propylene with chlorine in water.

[0004] However, in the above reaction, chlorine is added to the double bond of propylene to form propylene dichloride or to prevent side reactions such as formation of ethers by successive reactions. The reaction conditions in which the reaction is carried out while reducing the propylene chlorhydrin concentration and reducing the propylene chlorohydrin concentration are generally adopted. (MM.
P. Ferreo et al., Industrie Chmiq
ue Beige 19, 113, 1954).

Heretofore, the above reaction conditions have been realized by using a reactor called a so-called chlorohydrin column. That is, it has a gas-liquid separator provided with an exhaust gas outlet and a propylene chlorohydrin outlet, and from below the annular reactor having a U-shaped tube connected to the lower part of the gas-liquid separator, from the propylene and exhaust gas outlet. Supplying at least a part of the extracted exhaust gas, while circulating the reaction solution by using the gas lift by the bubbles as a driving force, supplying chlorine little by little in the downward flow region, and replenishing the reaction solution with water while supplying propylene chlorohydrin. A method of producing propylene chlorohydrin while keeping the concentration of chlorine and propylene chlorohydrin low in a reactor of a type in which propylene chlorohydrin is taken out is widely practiced. (Published by Nikkan Kogyo Shimbun; Nikkan Kogyo Seisho 14)
Propylene-based petrochemicals 106-110).

[0006]

On the other hand, effective use of petroleum resources has been increasingly regarded as important due to a decrease in petroleum resources and a corresponding rise in oil prices.

[0007] Therefore, in catalytic cracking in petroleum refining, it has become popular to recover a propylene-containing gas having a propylene content of 70 to 96% by volume from a by-product gas. desired.

In addition, in the above-mentioned conventional propylene chlorohydrin production technology and in many chemical reaction processes using propylene as a raw material, a part of the gas containing propylene that has passed through the reactor is circulated and used in the reactor. However, others are often incinerated as exhaust gas.
Such exhaust gas generally contains about 10 to 70% by volume of propylene.

[0009] Therefore, it is industrially very significant if the exhaust gas can be effectively used.

However, since these exhaust gases have an extremely low propylene content or various contents depending on the supply source, in order to utilize those exhaust gases as resources other than as fuel, it is necessary to concentrate, purify, etc. Is required. However, providing such means is costly and is not usually industrially feasible.

Therefore, it has been desired to develop a process which can effectively use gases containing various contents, particularly low contents of propylene, as raw materials without any concentration.

[0012]

DISCLOSURE OF THE INVENTION The present inventors have developed a process for producing propylene chlorohydrin capable of coping with various propylene contents, obtaining a high propylene utilization rate, and producing propylene chlorohydrin with a high selectivity. As a result of conducting various studies with the aim of developing a chlorine-dissolved aqueous solution through the flow path of the tubular reaction area, a propylene-containing gas was supplied to the chlorine-dissolved aqueous solution in the flow path, and a static mixing apparatus was developed. The mixing operation is performed at least once or more, and the opening at the rear end of the tubular reaction region is formed so that the aqueous medium is circulated. The chlorine supply port, the aqueous medium supply port, the propylene-containing gas supply port, and the propylene Connected to the aqueous medium supply port located downstream of the chlorine supply port of a reactor having a reaction liquid circulation system with a phosphorus aqueous solution outlet, and obtained from the rear end opening of the tubular reaction area A fluid containing propylene chlorohydrin, supplied as a reactor of the aqueous medium with the reaction solution circulating system, by taking out the propylene chlorohydrin solution than propylene chlorohydrin solution outlet which,
Using a propylene-containing gas having an arbitrary propylene content selected from a wide range, it has been found that propylene chlorohydrin can be produced with a high selectivity to a target substance and a high propylene utilization rate by a simple method, and completed the present invention. I came to.

That is, the present invention has a tubular reaction region for forming a one-way flow and an annular reaction region for forming a circulating flow with an ascending flow and a descending flow at a downstream end thereof, and the annular reaction region. Using a composite reactor having a gas-liquid separation zone, a chlorine-dissolved aqueous solution is supplied to the base end of the tubular reaction zone, and a propylene-containing gas is supplied to the downstream zone to perform a reaction. A method for producing propylene chlorohydrin, comprising completing the reaction and discharging an unreacted gas and an aqueous solution containing a product from the gas-liquid separation zone.

The most important feature of the present invention is that it flows in one direction,
It is to use a combined reactor in which a so-called tubular one-pass type reaction zone and a circulation type reaction zone are combined.

In the present invention, more preferably, propylene is sufficiently mixed in a tubular reaction zone at a place where propylene-containing gas is supplied or downstream thereof so that propylene is promptly dispersed and absorbed in an aqueous solution of chlorine. There is a need. For that purpose, the supplied propylene-containing gas is quickly subdivided, dispersed as finely as possible, and the mixed fluid is preferably sufficiently turbulent.
Supplying the propylene-containing gas through a perforated plate or increasing the flow rate of the fluid after the mixing are effective means. However, it is generally preferable to provide a mixing device.

Further, increasing the chlorine concentration (more preferably, the concentration of hypochlorous acid) in the aqueous solution of chlorine can reduce the amount of process water and obtain high selectivity for the target substance. It is effective because it can be
According to the findings of the present inventors and their co-workers, while dissolving chlorine in an aqueous medium, or after dissolving chlorine,
Adding an alkali to the aqueous solution to adjust the pH to a neutral side as long as the pH does not become alkaline, in particular, adjusting the pH to a range of 1 to 7, more preferably 3 to 6 and reacting with propylene. This makes it possible to obtain propylene chlorohydrin at a higher concentration and with higher selectivity for the target substance.

The pH is adjusted from the acidic side to the above pH.
When the pH is adjusted from the alkaline side, such as by introducing chlorine into the alkaline aqueous solution, chlorate is generated and chlorine is wasted, which is not preferable. On the other hand, if the pH exceeds 7, the reaction rate is extremely reduced, which is not preferable.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail for each step.

(Tube-type reaction zone) In the present invention, the reaction between chlorine and propylene in an aqueous medium is first performed in a tube-type reaction zone. That is, the method of the present invention separately supplies the propylene-containing gas to the flow path of the aqueous solution of chlorine in one place or several places and sequentially prevents the liquid after mixing the propylene-containing gas from mixing with the previous liquid. Meanwhile, the concentration of propylene chlorohydrin, which is a product in the flow path, is gradually increased, and the obtained fluid is introduced into the annular reaction zone.

The tubular reaction zone is not particularly limited as long as it constitutes a tubular flow path having no circulation flow path.

(Mixing Apparatus) In the present invention, in the tubular reaction zone, a mixing apparatus is provided in the flow line to mix a propylene-containing gas or, if necessary, chlorine into an aqueous solution flowing through the flow path. Is preferably provided. It is particularly preferable to use a static mixing device as the mixing device because it promotes rapid dissolution of these gases in an aqueous solution and can obtain a target product with high selectivity.

Known static mixers can be used without any limitation. Specifically, an ejector, a plate-shaped or cup-shaped collision plate type static mixing device, and a Kenics type, Sulzer type, Etoflo type, Tray H
i-mixer type, Bran & Lubbe type, N-form type, Komax type, Ligh
Tnin type, Ross ISG type, Prematechnik PMR type static mixing device and the like can be mentioned, but chlorine or propylene-containing gas can be dispersed as fine bubbles in an aqueous solution to expedite gas dissolution in downstream piping. Therefore, those having good gas-liquid dispersion performance are preferable. Examples of such a mixing device include an ejector, a plate-shaped or cup-shaped collision plate-type stationary mixing device, and a Kenics-type, Sulzer-type, or other static-type mixing device.

Further, as the stationary type mixing apparatus, it is preferable to select any one of a bubble flow, a plug flow and a slag flow, particularly a bubble flow, which is likely to be a bubble flow after mixing. Alternatively, a stationary mixing device such as a cup-shaped collision plate type static mixer or a Sulzer type is particularly preferable.

Further, in order to reduce the supply pressure of the gas containing chlorine and propylene, it is preferable that the pressure difference between the inlet and the outlet is small.

(Aqueous solution of chlorine and chlorine) In the present invention, the method of preparing the aqueous solution of chlorine dissolved in the flow channel of the tubular reaction zone is not particularly limited as long as it is adjusted to a concentration required for the reaction with propylene. Not done. For example, before being supplied to the tubular reactor, a dissolving tank may be provided, and chlorine may be blown into water in the tank, and may be prepared using a known gas absorbing device. A method in which water is supplied to the tubular reaction region and chlorine is supplied to mix and prepare the mixture is preferable. In this case, in order to achieve the rapid absorption of chlorine into water, it is preferable to provide a gas-liquid mixing device in the tubular reaction region at or near the chlorine supply location.

Further, the chlorine concentration of the prepared aqueous solution of dissolved chlorine is reduced by the reaction with the supplied propylene while flowing through the tubular reaction zone. Therefore, chlorine can be supplied in the middle of the flow path of the tubular reactor to adjust the chlorine concentration in the aqueous solution of chlorine. Also in this case, after supplying chlorine, a mixing device is provided in the line and mixed,
This is preferable because chlorine can be efficiently dissolved in the aqueous solution of chlorine.

The supply of chlorine to the tubular reactor is performed upstream of the mixing device except when an ejector is used as the mixing device. In the case of the ejector, water for process is used as a fluid for driving the ejector. A supply port is provided inside the ejector because a method of supplying chlorine by sucking it as axial gas can be used. This is the same when supplying a propylene-containing gas described later.

When chlorine is supplied to the subsequent annular reaction zone, it is generally supplied in gaseous form directly to the reaction zone, and the chlorine concentration in the chlorine-dissolving aqueous solution is generally adjusted by the circulation amount of the reaction solution to be circulated. It is. As will be described later, when supplying a propylene-containing gas also in the annular reaction region, it is necessary to supply chlorine upstream of the propylene-containing gas to prepare an aqueous solution of chlorine.

In the present invention, the chlorine may be gaseous purified chlorine once liquefied and vaporized, but it is economical to use unpurified gaseous chlorine having a purity of about 99% containing oxygen and moisture generated by electrolysis. And preferred.

It is sufficient that the supply pressure of chlorine overcomes the pressure of the liquid flowing in the flow path and is high enough to supply gaseous chlorine. Usually, it is in the range of 1K Pascal gauge to 700K Pascal gauge.

The supply amount of chlorine is not particularly limited as long as it is lower than the solubility of chlorine determined by pressure and temperature, but if it is too large, by-products tend to increase. And tends to induce not only the size of the reactor but also side reactions.

Therefore, usually, the chlorine concentration inside the flow channel of the reactor is in the range of 500 to 20,000 ppmw, especially 800 to 20,000 ppmw.
It is preferable to supply chlorine so as to be in the range of 15000 ppmw.

The tubular reaction zone may be constructed by providing a plurality of sets of the above-mentioned chlorine and propylene gas supply and mixing locations in one tubular reactor, or may be provided with the supply of chlorine and propylene gas and the mixing locations. A plurality of single tubular reaction regions may be connected in series.

In a case where a plurality of tubular reactors are connected in series to the tubular reaction region, it is also a preferable embodiment that a pump is provided at the connection to recover the supply pressure of the liquid.

The flow direction of the fluid in the tubular reaction region may be horizontal, inclined, or vertical. However, when installed horizontally or inclined, a laminar flow or a wavy flow is likely to occur, resulting in poor gas absorption efficiency. Since it is necessary to increase the length of the pipe for gas absorption, it is necessary to install the pipe so that the gas flows downward in the vertical direction as much as possible. It is particularly preferable because the scale-up is easy.

(Water) In the present invention, the supply pressure of water or an aqueous solution of chlorine dissolved in the tubular reaction zone is not particularly limited. It is sufficient that the sum of the pressure losses of the mixing device described later is equal to or higher than the atmospheric pressure, and is usually 1K Pascal gauge to 500
It is preferably in the range of K Pascal gauge.

When the supply water is used as a driving force of an ejector which is a mixing device, it is preferable that the pressure is equal to or higher than a pressure necessary for driving the ejector in order to guarantee complete gas absorption.

In the present invention, the flow rate of the water or the aqueous solution of chlorine dissolved supplied to the tubular reaction zone can sufficiently bring out the gas mixing performance, and the flow state of the fluid after the gas mixing can be a bubble flow, a plug flow, or a slag flow. It is preferable to adjust any one of the flows, especially the bubble flow.

Although the above-mentioned suitable flow rate cannot be limited unconditionally, usually, when a static mixing apparatus is used, the flow rate of the liquid introduced into the mixing apparatus is 0.3 to 4 m / sec, preferably 0.7 to 4 m / sec. The range is 3 m / sec.

In general, the flow rate can be adjusted by adjusting the flow rate of water or an aqueous solution of chlorine to be supplied to the tubular reaction zone and the diameter of the pipe in the tubular reaction zone (Chemical Engineering Handbook, 5th edition, 272-27). P. 276, edited by the Society of Chemical Engineers).

(Propylene-containing gas)
The propylene-containing gas is not particularly limited as long as it contains propylene, but is generally in the range of 5 to 100% by volume, preferably in the range of 10 to 100% by volume, and more preferably 1 to 100% by volume.
It is in the range of 2 to 100% by volume. Further, there is no problem at all if a gas obtained by mixing an exhaust gas having a low propylene content or the like with a gas having a high content to adjust the propylene content to an arbitrary content is used.

Specific examples of such a propylene-containing gas include an exhaust gas having a propylene content of about 10 to 70% by volume discharged during the production of propylene chlorohydrin, which is recovered from by-product gas in catalytic cracking in petroleum refining. With a propylene content of about 70 to 96% by volume
C-recovered propylene-containing gas, propylene-containing gas produced from naphtha cracking with a propylene content of 92 to 100% by volume, propylene discharged during production of isopropyl alcohol, cumene, acetone, acrolein, acrylic acid, acetonitrile, allyl chloride, polypropylene, etc. Exhaust gas having a content of 10 to 70% by volume can be mentioned. In particular, exhaust gas having a propylene content of about 10 to 70% by volume discharged when producing propylene chlorohydrin, and by-product gas in catalytic cracking in petroleum refining With propylene content of about 70 to 96% by volume
C-recovered propylene-containing gas, propylene-containing gas having a propylene content of 92 to 100% by volume produced from naphtha cracking is preferred.

The component other than propylene is preferably an inert gas which does not take part in the reaction during the production of propylene chlorohydrin from the viewpoint of the ease of purification of propylene oxide subsequently produced from the target product. Specifically, butane, isobutane, propane, cyclopropane, ethane, hydrocarbons such as methane, nitrogen, hydrogen, oxygen,
Examples thereof include carbon monoxide and carbon dioxide. When oxygen is contained, it is safe to add propane, nitrogen, etc. so that the exhaust gas discharged from the reaction zone having a reaction liquid circulation system connected to the latter stage of the tubular reaction zone described later does not enter the explosion range. Above.

It is sufficient that the supply pressure of the propylene-containing gas is sufficient to overcome the pressure of the fluid flowing through the tubular reaction zone and the reaction liquid circulation system. Usually, it is in the range of 1K Pascal gauge to 700K Pascal gauge.

When the supply amount of the propylene-containing gas is too large, unreacted substances tend to increase, and when the supply amount is too small, by-products tend to increase. A range of 0.9 to 2, especially 1 to 1.5, in terms of the mole number of propylene pure is recommended.

The supply position of the propylene-containing gas should be a position where the supplied chlorine is sufficiently dissolved in both the case where chlorine is supplied in the flow path of the tubular reaction region in the first stage and the case where the supplied chlorine is dissolved in the annular reaction region in the second stage. Is preferred. Such a position may be determined in advance by an experiment, but it is usually preferable to secure a residence time of 4 seconds or more after mixing chlorine to ensure complete dissolution of chlorine.

On the other hand, after mixing the propylene-containing gas, 10%
It is preferable to secure a stay time of seconds or more.

(Adjustment of pH of Chlorine-Dissolved Aqueous Solution) In the present invention, the pH of the chlorine-dissolved aqueous solution flowing through the channel
An embodiment in which an alkali is added in a range where H does not become 7 or more is preferable because the selectivity of the obtained propylene chlorohydrin increases.

That is, when chlorine is dissolved in water, a reversible reaction occurs in which chlorine reacts with water to generate hypochlorous acid and hydrochloric acid. In the method of the present invention, the generated hydrochloric acid is selected from the magnitude of its dissociation multiplier (hypochlorous acid 4 × 10 ⁻⁸ , hydrochloric acid 1 × 10 ⁻¹ ) because alkali is supplied to chlorine dissolved in water. Neutralized to form salts. As a result, in the reversible reaction, a reaction for generating hypochlorous acid is promoted, and an aqueous solution having a very low chlorine concentration and a high hypochlorous acid concentration can be obtained. In the present invention, by supplying propylene to such a solution stream, it is possible to suppress the generation of by-products caused by the addition of chlorine to the double bond of propylene, and it is possible to suppress the production of It appears that the phosphorus selectivity will be even higher.

The kind of alkali supplied for adjusting the pH is not particularly limited, but alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, magnesium hydroxide, calcium hydroxide, hydroxide Alkaline earth metal hydroxides such as barium, alkali metal carbonates such as sodium carbonate, sodium bicarbonate, and potassium carbonate, and alkaline earth metal carbonates such as magnesium carbonate and calcium carbonate are preferable, and are easily available. Thus, calcium hydroxide is particularly preferred.

The amount of alkali added must be within the range not exceeding pH 7 of the aqueous solution of chlorine as described above, and is preferably pH 1 to 7, particularly pH 3 to 6.
It is preferable to control the supply amount of the alkali so as to fall within the range, since a solution having a low chlorine concentration and a high hypochlorous acid concentration can be obtained.

The method of supplying the alkali is not particularly limited, but it is usually preferable to continuously supply the solution as a 1 to 40% by weight aqueous solution or slurry. At this time, it is preferable to control the pH by using a pH control unit including a pH detection unit for the fluid in the tubular reaction region and a valve for adjusting the flow rate of the alkali based on the signal.

The addition of the alkali is preferably carried out using the same static mixer as used for the gas.

Since chlorine dissolves in water in a very short time by the addition of an alkali, it is possible to shorten a suitable staying time after the chlorine is mixed. Usually, such a staying time of 2 seconds or more is sufficient. Becomes

(Connection between tubular reaction zone and annular reaction zone)
In the present invention, one of the important requirements is to supply a propylene-containing gas to the chlorine-dissolved aqueous solution in the flow path of the chlorine-dissolved aqueous solution so that the reaction is performed in one pass, and then, the reaction mixture fluid is formed into a tubular type. Introducing into the annular reaction region connected to the rear end of the reaction region, completing the target reaction while the reaction mixture fluid is circulated in the annular reaction region, and
Unreacted gas and aqueous solution of the reaction product are removed after gas-liquid separation.

In the present invention, the reaction rate in each of the tubular reaction zone and the annular reaction zone in each reaction zone is not particularly limited, but generally 50% or more of the pure propylene supplied in the tubular reaction zone is not limited to the above. It is preferable to configure the reaction in the tubular reaction zone. In particular, the higher the propylene content in the propylene-containing gas used, the higher the reaction rate of propylene in the reaction zone, which eventually makes it possible to obtain propylene chlorohydrin at a higher concentration and a higher selectivity. Is preferred. Further, the chlorine supplied in the tubular reaction region need not be completely consumed at the rear end of the tubular reaction region.

Of course, a propylene-containing gas and / or a chlorine gas (or an aqueous solution in which chlorine is dissolved) can be newly supplied to the annular reaction region as needed.

In general, the propylene-containing gas should be supplied to a location providing a driving action to assist circulation of the fluid in the annular reaction zone, and the chlorine should be supplied upstream from the propylene-containing gas supply port. When both chlorine and propylene-containing gas are supplied to the annular reaction region, in the flow direction of the circulating fluid, supply of chlorine, introduction of fluid from the tubular reaction region, and supply of propylene-containing gas are sequentially performed from the upstream side. It is preferable to order. This makes it possible to smoothly dissolve chlorine in the annular reaction region and suppress side reactions.

More specifically, when a reactor utilizing a gas lift described later is selected, chlorine is supplied to the downward flow area of the circulating liquid in the annular reaction area, and the fluid from the tubular reaction area is supplied near the lower part. And it is preferable to supply a propylene-containing gas to the vicinity of the portion where the flow turns into an upward flow.

The joining angle of the fluids is not particularly limited, but is preferably a connection angle that does not hinder the flow of the circulating fluid, and is preferably within 90 ° with respect to the mutual fluid flow direction. In particular, it is preferably within 60 °, more preferably within 45 °.

Further, in the present invention, examples of a reactor for forming a suitable annular reaction zone include the above-mentioned conventional methods, that is, equipped with an exhaust gas outlet and a propylene chlorohydrin outlet called a so-called chlorohydrin column. It has a gas-liquid separator and supplies at least a part of the propylene-containing gas and at least a part of the exhaust gas extracted from the exhaust gas outlet from below the reactor in which a U-shaped pipe is connected to the lower part of the gas-liquid separator. Supplying chlorine little by little in the downward flow area while circulating the reaction solution using the gas lift as the driving force, and supplying propylene chlorohydrin while supplying water to the reaction solution, and supplying chlorine to the flow path And a gas-liquid separator having a mixer and a propylene supply port in sequence and a mixing device provided downstream of the supply port, respectively. Was connected to the gas-liquid separator, and the reaction solution separated by the gas-liquid separator was supplied to the front end opening of the tubular reactor via a circulation pump to form a circulation system. Although a reactor can be exemplified, it is particularly preferable to use the former reactor called a chlorohydrin column because the propylene utilization can be stably improved.

The number of the chlorohydrin towers to be installed may be one to three in series, and the exhaust gas may be brought into countercurrent contact to increase the propylene utilization rate and the propylene chlorohydrin selectivity to increase the concentration. It is preferable because it is possible.

(Amount of Load in Tubular Reaction Zone and Annular Reaction Zone) In the present invention, the ratio of the supply amounts of chlorine and propylene to the tubular reaction zone and the annular reaction zone can be selected arbitrarily. May be determined depending on which reactor is used as the main reactor.

In general, when it is desired to improve the selectivity, the amount of the raw material supplied to the former tubular reaction region may be increased, and when it is desired to improve the utilization ratio of propylene, the amount of the raw material supplied to the latter annular reaction region may be increased. I just need.

A part of the exhaust gas discharged from the subsequent annular reaction zone is discharged as a purge gas, but a part of the exhaust gas is supplied to the propylene-containing gas supply port of the reactor and the tubular reaction zone. Propylene chlorohydrin can be produced by circulating it as a gas to further increase propylene utilization.

Further, a small amount of propylene remaining in the purge gas discharged out of the system is equivalent to the propylene which has already been proposed in Japanese Patent Application No. 2000-3.
By the method described in the specification of No. 47514,
Furthermore, it can be taken out as an aqueous solution of propylene chlorohydrin.

(Reaction Temperature, etc.) In the present invention, if the reaction temperature is too high, the selectivity of the target propylene chlorohydrin tends to be low. It is preferable to adjust the temperature to not more than ° C. Although there is no particular limitation on such an adjusting method, a method of adjusting the temperature of water or an aqueous solution of chlorine to be supplied to the tubular reaction region is preferable. That is, the temperature of the water or the aqueous solution of chlorine dissolved supplied to the tubular reaction region is preferably 70 ° C. or less in consideration of the reaction heat of formation of propylene chlorohydrin, and particularly preferably in the range of 0 to 60 ° C. Is preferred.

Thus, chlorine, a propylene-containing gas of any propylene content selected from a wide range, and water are
By passing through the tubular reaction zone and the cyclic reaction zone, chlorhydrin can be stably produced in a simple manner, with high target product selectivity and high propylene utilization.

The material constituting the composite reactor of the present invention is not particularly limited as long as there is no problem such as corrosion except for the nozzle portion of the chlorine supply port. For example, a lining made of a polymer material such as polytetrafluoroethylene or a corrosion-resistant metal material such as Ti can be exemplified. Since the nozzle portion of the chlorine supply port reacts with chlorine when Ti is used, it is preferable to use a polymer material such as polytetrafluoroethylene.

The aqueous solution of propylene chlorohydrin obtained by the method of the present invention can be used as it is as a raw material for producing propylene oxide.

Hereinafter, a typical embodiment of the above method will be described with reference to FIG.
2 will be described.

FIG. 1 shows a typical embodiment of the present invention.

That is, in the embodiment shown in FIG.
The chlorine A is dispersed in water as fine bubbles by being mixed into the mixing device 13 with the chlorine supplied from the chlorine gas supply port 12.

Next, the water containing the chlorine A is dissolved in the chlorine in the flow path 14 of the tubular reaction area, and is dissolved by the time the water reaches the propylene-containing gas supply port 15. Be prepared.

Thereafter, the propylene-containing gas B is supplied from the gas supply port 15 to the flow channel, and is supplied to the aqueous solution of chlorine dissolved passing through the flow channel.

The supplied propylene-containing gas is mixed with the aqueous solution of chlorine in the mixing device 16, and the propylene-containing gas is dispersed as fine bubbles in the aqueous solution of chlorine.

In the flow path 17 following the mixing device, the reaction of propylene, chlorine and water proceeds, the production of propylene chlorohydrin and hydrogen chloride proceeds, and the reaction proceeds in an aqueous solution containing propylene chlorohydrin and a propylene-containing gas. A fluid containing propylene chlorohydrin mixed with components other than propylene and a gas-liquid mixture of unreacted propylene is obtained.

On the other hand, the annular reaction region 21 is
Chlorine A is supplied from 2, and the dissolution of chlorine gas proceeds by the action of the circulating reaction solution, and most of the chlorine dissolves in the reaction solution before reaching the aqueous medium supply port 31.

Next, the chlorine-dissolved aqueous solution, the fluid introduced from the tubular reaction zone through the line 1 and the components other than propylene contained in the propylene-containing gas at the position of the aqueous medium supply port 31, and unreacted propylene The fluid containing propylene chlorohydrin in which gas and liquid are mixed joins.

At this time, if the merging angle of the two fluids is within 60 °, the flow of the circulating flow becomes even smoother.

Thus, the propylene-containing gas and the gas discharged from the gas supply port 23 below the annular reaction region 21 and the exhaust gas outlet 25 in the gas phase of the gas-liquid separator located above the annular reaction region 21 are extracted. A part of the exhaust gas is pressurized by a pressurizing pump 27 via a line 26 and supplied as a reaction liquid circulation drive source.

A newly added propylene-containing gas;
The fluid containing propylene chlorohydrin in which a gas-liquid mixture of components other than propylene and unreacted propylene contained in the propylene-containing gas is mixed, is formed into a cyclic reaction region 2
1 While rising inside, the propylene component reacts with the aqueous solution of chlorine and propylene chlorohydrin is further generated,
The concentration of propylene chlorohydrin in the reaction solution increases.

A part of the exhaust gas extracted from the exhaust gas outlet 25 is discharged from the purge gas outlet 28 as a purge gas. This purge gas can be incinerated as it is, and a propylene recovery facility can be further attached at a later stage.

The produced propylene chlorohydrin is taken out as an aqueous propylene chlorohydrin solution D via an outlet 24 for the aqueous propylene chlorohydrin solution.

FIG. 2 shows another representative embodiment.

The apparatus shown in FIG. 2 is a combined reactor illustrating another exemplary embodiment of the present invention. That is, p
It shows an embodiment for adjusting H by adding an alkali.

The apparatus shown in FIG. 2 is provided with an alkali supply port 42 having a control valve 41 for adding the aqueous alkali solution E while controlling the pH to the flow path immediately after the flow path 14 for preparing the aqueous chlorine solution. , Downstream of the mixing device 4
3. a pH detector 45; and a calculator 4 for converting a signal from the pH detector 45 into a signal for controlling the control valve 41.
4 is provided to control the control valve 41.

[0088]

As will be understood from the above description, according to the present invention, in a method for producing propylene chlorohydrin by reacting chlorine and propylene in water, any propylene content selected from a wide range is provided. By using the propylene-containing gas described above, propylene chlorohydrin can be industrially advantageously produced with a high selectivity for a target substance and a high propylene utilization rate.

Therefore, the industrial value of the present invention is extremely high.

[0090]

The present invention will be described in more detail with reference to the following Examples, which by no means limit the scope of the present invention.

Example 1 The apparatus shown in FIG. 1, that is, a pipe-type reaction zone for forming a unidirectional flow, having a pipe inner diameter of 27.6 mm, a pipe length of 20 m after mixing a propylene-containing gas, and a chlorine supply port and a propylene-containing gas At the downstream end of the tubular reaction zone equipped with a supply port and a mixing device for mixing chlorine and propylene-containing gas, the upper part is expanded to form a gas-liquid separation zone, and the circulating flow with ascending and descending flows And a liquid reactor having a ring-shaped reaction zone having a ring-shaped reaction zone. They were connected so as to join at an acute angle of ゜.

[0092] Water was poured from the pipe end of the pipe type reaction zone to the end of the pipe.
It is supplied at a rate of 2 m ³ / Hr and chlorine is added at 5.25 Nm ³ / H
r, and a propylene-containing gas having a propylene content of 95% was supplied at a rate of 5.80 Nm ³ / Hr to perform the first-stage chlorhydrination reaction to obtain a reaction liquid stream.

Next, the reaction solution in the annular reaction zone where the reaction solution is circulated by the gas lift of the propylene-containing gas is
Chlorine is supplied from the chlorine supply port at a rate of 12.5 Nm ³ / Hr, is combined with the tubular reaction liquid stream, and is supplied from the propylene mixed gas supply port with a propylene-containing gas having a propylene content of 95% and a gas-liquid separation zone. A circulating gas of 8.8 Nm ³ / Hr was supplied from the exhaust gas discharged from the discharge gas discharge outlet, and a second-stage chlorhydrination reaction was performed.

An aqueous solution of propylene chlorohydrin at a rate of 3.3 m ³ / Hr from the outlet of the reaction system and 1.0 N
A purge gas was obtained at a rate of m ³ / Hr.

When the obtained aqueous solution and gas were analyzed, the propylene chlorohydrin selectivity was 95.5% and the propylene conversion was 99.5%. Table 1 shows the operating conditions and results.

Examples 2 to 3 The same procedure as in Example 1 was carried out except that chlorine and propylene-containing gas were supplied at the contents and supply amounts shown in Table 1. Table 1 shows the results.

Examples 4 to 6 The apparatus shown in FIG. 2, that is, the apparatus in which a device for adjusting the pH of the aqueous solution of chlorine dissolved by adding alkali is added downstream of the chlorine supply port in the tubular reaction zone, As one
Using 7% lime milk to supply pH from alkaline supply port
Was controlled to 4 and the chlorhydrination reaction was carried out under the conditions shown in Table 1 in the same manner as in Example 1. Table 1 shows the results.

Comparative Examples 1 and 2 Water was supplied from the upper portion of the chlorine supply port of the apparatus shown in FIG. 3, that is, an apparatus comprising only a cyclic reaction zone, and a chlorhydrination reaction was carried out under the conditions shown in Table 1. (See FIG. 3). Table 1 shows the results.

[0099]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a typical apparatus used in the method of the present invention.

FIG. 2 is a conceptual diagram showing an embodiment of another typical apparatus used in the method of the present invention.

FIG. 3 is a conceptual diagram showing an embodiment of a typical apparatus used in a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tube reactor 2, 51 Water supply port 12, 22 Chlorine supply port 13 Static mixing apparatus for chlorine mixing 14 Flow path for chlorine dissolution 15, 23 Propylene-containing gas supply port 16 Static mixing for propylene mixing Apparatus 17 Flow path for reaction 21 Liquid circulation type reactor 24 Propylene chlorohydrin aqueous solution outlet 25 Exhaust gas outlet 26 Circulating gas pipe 27 Boost pump 28 Purge gas outlet 31 Aqueous medium supply port 41 Control valve 42 Alkaline supply port 43 Static Mixing Device for Alkaline Mixing 44 Operation Unit 45 pH Detector

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomoaki Fujii 1-1 Mikage-cho, Tokuyama-shi, Yamaguchi Pref. (72) Inventor Manabu Kamamoto 1-1, Mikage-cho, Tokuyama-shi, Yamaguchi Pref. (72) Inventor Kojiro Miyazaki 1-1 Mikage-cho, Tokuyama-shi, Yamaguchi Pref. FE11 FE71 FE75

Claims (5)

[Claims] 1. A tubular reaction region forming a one-way flow and an annular reaction region forming a circulating flow with an ascending flow and a descending flow at a downstream end thereof, wherein the annular reaction region is a gas-liquid separation region. Using a complex type reactor having a, a chlorine-dissolved aqueous solution is supplied to the base end side of the tubular reaction region, and a propylene-containing gas is supplied to the downstream region to perform a reaction.
A method for producing propylene chlorohydrin, comprising completing the reaction and discharging an unreacted gas and an aqueous solution containing a product from the gas-liquid separation zone. 2. The method according to claim 1, wherein the chlorine concentration in the aqueous solution of chlorine is adjusted by controlling the pH of the aqueous solution of chlorine in the channel within a range of 1 to 7 while supplying chlorine to the channel. A method for producing propylene chlorohydrin according to claim 1. 3. The method according to claim 1, wherein the reaction fluid supplied from the tubular reaction region to the annular reaction region is joined at an acute angle of 60 ° or less with respect to the flow direction of the fluid flowing in the annular reaction region. 3. The method for producing propylene chlorohydrin according to 1 or 2. 4. The process for producing propylene chlorohydrin according to claim 1, wherein a reactor having an in-line mixing device is used after the supply of the propylene-containing gas. 5. The propylene-containing gas according to claim 1, wherein the propylene content is at least 10% by volume.
The method for producing propylene chlorohydrin according to any one of the above.