KR20130056242A - Process for production of alkylene carbonates and/or alkylene glycols - Google Patents

Abstract

In the presence of a catalyst and an alkali metal carbonate, alkylene carbonate, water and carbon dioxide are reacted to produce alkylene carbonate and / or alkylene glycol, and alkylene carbonate and / or from the reaction liquid obtained in the reaction step. In a method for producing an alkylene carbonate and / or an alkylene glycol having a catalyst circulation step of recovering alkylene glycol and circulating a catalyst liquid containing a catalyst in a reaction step, precipitates are formed in the reaction system while maintaining a hydrolysis rate. An object of the present invention is to provide a manufacturing method that can be stably operated for a long time without being accumulated. The method of this invention includes the process of removing the alkali metal chloride derived from the said alkali metal carbonate, or the chlorine ion derived from this alkali metal chloride in a reaction liquid.

Description

Process for producing alkylene carbonate and / or alkylene glycol {PROCESS FOR PRODUCTION OF ALKYLENE CARBONATES AND / OR ALKYLENE GLYCOLS}

In the present invention, alkylene oxide is produced by reacting alkylene oxide and carbon dioxide in the presence of a catalyst and an alkali metal carbonate, and generating alkylene glycol by hydrolyzing the alkylene carbonate in the reaction solution. It relates to a process for the preparation of carbonates and / or alkylene glycols.

Ethylene glycol is produced on a large scale by a method of directly reacting ethylene oxide with water to hydrolyze. In this method, in order to control by-products such as diethylene glycol and triethylene glycol during hydrolysis, Excessive water must be used rather than stoichiometric amount. For this reason, it is necessary to distill the produced | generated ethylene glycol aqueous solution and to dehydrate excessive amount of water, and there exists a problem that a lot of energy is needed to acquire refined ethylene glycol.

As a method of solving this problem, the method of manufacturing ethylene glycol by making water and ethylene oxide react in presence of carbon dioxide is proposed. This reaction generates ethylene carbonate (hereinafter referred to as the "carbonated process") by reaction of ethylene oxide and carbon dioxide, and then generates ethylene glycol by hydrolyzing ethylene carbonate (hereinafter referred to as "hydrolysis process"). Reaction is carried out in two steps. In the hydrolysis of ethylene carbonate, since diethylene glycol, triethylene glycol, and the like are hardly produced by-products, hydrolysis can be performed with a little excess of water than stoichiometry, thereby greatly reducing the cost of dehydration of the produced ethylene glycol aqueous solution. Can be. Moreover, since carbon dioxide is produced by hydrolysis of ethylene carbonate, this carbon dioxide is circulated and used. It is also possible to produce ethylene carbonate by extracting the ethylene carbonate produced as an intermediate in this method.

In the above method, deterioration of the activity of the catalyst has been a problem in the carbonation step until now, and as a countermeasure, the activity of the carbonation catalyst is lowered by returning the condensate accompanying carbon dioxide released in the hydrolysis step to the carbonation step. In the organic solvent, an inorganic iodide or an inorganic bromide was added to the catalyst solution because it was found that the cause of the activity of the catalyst (see Patent Literature 1) and the catalyst of the carbonation step was chlorination. The method of regenerating a catalyst by precipitating and removing the chloride derived from a carbonation catalyst is disclosed (refer patent document 2).

However, the activity reduction of the catalyst in the hydrolysis step and the prevention method thereof have not been disclosed so far.

Japanese Unexamined Patent Publication No. 2000-143563 Japanese Unexamined Patent Publication No. 2004-292384

The present invention is a reaction step of reacting alkylene oxide, water and carbon dioxide in the presence of a catalyst and an alkali metal carbonate to produce alkylene carbonate and / or alkylene glycol, and alkylene carbonate from the reaction solution obtained in the reaction step. And / or a method for producing an alkylene carbonate and / or an alkylene glycol comprising a catalyst circulation step of recovering alkylene glycol and circulating a catalyst liquid containing a catalyst in a reaction step, wherein the reaction system is maintained while maintaining a hydrolysis rate. An object of the present invention is to provide a manufacturing method that can be stably operated for a long time without depositing precipitates in the container.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, first, as a result of examining the cause of the activity fall of a hydrolysis catalyst, potassium carbonate which exists in a reaction system changes to potassium chloride as reaction progresses, As a result, the valence of ethylene carbonate It was found that the rate of decomposition reaction was lowered. Specifically, the reason for the decrease in the rate of the hydrolysis reaction is that in order to improve the selectivity of the reaction in the production process of ethylene oxide as a raw material, chlorohydrocarbon is supplied as the selectivity regulator, and this chlorohydrocarbon is used to produce ethylene glycol or ethylene carbonate. It was thought that the potassium carbonate contained in the reaction liquid was converted into potassium chloride by gradually mixing it in a small amount and decomposing to become chlorine ions, thereby slowly decreasing the rate of hydrolysis reaction of ethylene carbonate.

As a result of analyzing the organic chlor compound present in the reaction system, a high concentration of organic chlor compound is retained at 80 to 420 ppm in the condensate obtained when cooling the excess carbon dioxide recovered from the carbonation step or the carbon dioxide released from the hydrolysis reactor. I could see that I was doing.

That is, the organic chlor compound which causes the hydrolysis reaction to fall is concentrated in the liquid which condensed the gas containing carbon dioxide discharged from a carbonation reactor or a hydrolysis reactor, and is recovering this liquid, It was found that the organic chlor compound gradually accumulates in the process, and the accumulated organic chlor compound gradually decomposes, and the potassium carbonate used as the hydrolysis catalyst is neutralized by chlorine ions. Therefore, it has been found that by bleeding a liquid containing an organic chlor compound out of the system, it is surprisingly possible to prevent the chlorination of the hydrolysis catalyst and to prevent the activity degradation of the hydrolysis catalyst.

The carbon dioxide condensate discharged from the carbonation process or the hydrolysis reactor contains about 5% to 30% of ethylene glycol, which causes the problem of bleeding ethylene glycol at the same time as the chlorine ion (organic chlor compound) is bleeded. However, it has been found that the organic chlor compound can be distilled off from ethylene glycol without being decomposed by distillation under conditions without potassium carbonate.

Based on these findings, the present inventors maintain the hydrolysis rate by carrying out the reaction while removing the alkali metal chloride derived from the alkali metal carbonate (hydrolysis catalyst) or the chlorine ion derived from the alkali metal chloride in the reaction solution. It was found out that the precipitate can be operated stably for a long time without generating precipitates in the reaction system.

In short, the gist of the present invention,

(1) An alkylene carbonate from a reaction step of reacting alkylene oxide, water and carbon dioxide to produce alkylene carbonate and / or alkylene glycol in the presence of a catalyst and an alkali metal carbonate, and a reaction solution obtained in the reaction step. And / or a process for recovering alkylene glycol, and a method for producing alkylene carbonate and / or alkylene glycol, comprising a catalyst circulation step of circulating a catalyst liquid containing a catalyst in a reaction step,

A method for producing an alkylene carbonate and / or alkylene glycol, comprising the step of removing an alkali metal chloride derived from the carbonate of the alkali metal or a chlorine ion derived from the alkali metal chloride in the reaction solution.

(2) The step of removing the alkali metal chloride derived from the carbonate of the alkali metal in the reaction solution acquires a part or the whole amount of the reaction solution containing the catalyst in the reaction step and at least the alkylene glycol contained in the reaction solution. Part (1) of distilling off and separating solids precipitated in the distillation separation, wherein the catalyst circulating step circulates the residual liquid from which the solids precipitated in the distillation separation is circulated in the reaction step. A process for preparing the alkylene carbonates and / or alkylene glycols described,

(3) The step of removing the alkali metal chloride derived from the carbonate of the alkali metal in the reaction solution acquires a part or the whole amount of the reaction solution containing the catalyst in the reaction step and at least the alkylene glycol contained in the reaction solution. After distilling a part and separating solids precipitated in the distillation, the catalyst circulating step further separates and recovers the catalyst from the residual liquid from which the solid precipitated in the distillation is separated. Method for producing alkylene carbonate and / or alkylene glycol according to (1), wherein the recovered catalyst is circulated in the reaction step,

(4) The method for producing the alkylene carbonate and / or alkylene glycol according to (2) or (3), wherein the precipitated solid is separated at 80 ° C or higher.

(5) The reaction step is a carbonation step of reacting alkylene oxide and carbon dioxide in the presence of a catalyst and an alkali metal carbonate to produce an alkylene carbonate, and hydrolyzing the alkylene carbonate in the reaction solution of the carbonation step. A hydrolysis process for producing alkylene glycol,

The removal process of the chlorine ion derived from the said alkali metal chloride,

The condensation step of cooling the gas containing carbon dioxide released in the carbonation step and / or the hydrolysis step, and the alkalinity of the catalyst liquid circulated from the catalyst circulation step to the reaction step is 0.03 mol / mol or more with respect to the catalyst concentration. The manufacturing method of the alkylene carbonate and / or alkylene glycol as described in (1) containing the process of discharging the condensate obtained by the condensation process,

(6) The alkylene carbonate according to (5), wherein in the chlorine ion removal step, the condensate is dehydrated again to remove water and organic chlor compound contained therein, and then the remaining liquid is circulated to the reaction step. Or a method for preparing alkylene glycol,

(7) The method for producing the alkylene carbonate and / or alkylene glycol according to (6), wherein the organic chlor compound is ethylene chlorhydrin,

(8) The place where the condensate is circulated is a hydrolysis reaction solution supply stage of a distillation column for distilling water contained in the hydrolysis reaction solution obtained in the hydrolysis step or above (5) to (7). The method for producing the alkylene carbonate and / or alkylene glycol according to any one of claims,

(9) A method for producing the alkylene carbonate and / or alkylene glycol according to any one of (1) to (8), wherein the carbonate of the alkali metal is further added to the reaction step.

(10) The method for producing the alkylene carbonate and / or the alkylene glycol according to any one of (1) to (9), wherein the alkylene carbonate is ethylene carbonate and the alkylene glycol is ethylene glycol.

Is in.

1 is a ratio of the catalyst concentration of the alkalinity (concentration of the OH group of the hydrolysis catalyst contained in the catalyst liquid) of the catalyst liquid circulated in the carbonation process in the reaction system for discharging the condensate obtained in the hydrolysis step out of the reaction system; This graph shows the relationship with the number of driving days.
FIG. 2 is a graph showing the relationship between the concentration of chlorine ions for potassium contained in the catalyst liquid circulated by the carbonation process and the number of operating days in the reaction system for discharging the condensate obtained in the hydrolysis step out of the reaction system.
3 is a graph showing the relationship between the ratio of the catalyst concentration of alkalinity of the catalyst liquid circulated in the carbonation process and the number of operating days in the reaction system in which the condensate obtained in the hydrolysis step is not discharged out of the reaction system.

EMBODIMENT OF THE INVENTION Hereinafter, although this invention is demonstrated in detail, this invention is not limited to embodiment shown below, an example, etc., It can change arbitrarily and can implement in the range which does not deviate from the summary of this invention.

The present invention provides an alkylene reaction in which an alkylene oxide, water and carbon dioxide are reacted to produce an alkylene carbonate and / or an alkylene glycol in the presence of a catalyst and an alkali metal carbonate, and alkylene from the reaction liquid obtained in the reaction step. A method for producing an alkylene carbonate and / or an alkylene glycol comprising a step of recovering carbonate and / or alkylene glycol and a catalyst circulation step of circulating a catalyst liquid containing a catalyst in a reaction step, wherein It is a method characterized by including the process of removing the alkali metal chloride derived from the carbonate of an alkali metal, or the chlorine ion derived from this alkali metal chloride.

The reaction process of this invention means both the "carbonation process which produces | generates an alkylene carbonate", and the "hydrolysis process which hydrolyzes the alkylene carbonate in the reaction liquid after the said carbonation process again." Although a carbonation process and a hydrolysis process are demonstrated below, it is not limited to two separate reaction systems, You may carry out in the same reactor.

(1) Carbonation Process

As a catalyst of a carbonation process (this may be called a "carbonate catalyst" in this specification), the bromide or iodide of an alkali metal, the halide of an alkaline earth metal, the alkylamine, the quaternary ammonium salt, and organic tin Or what is necessary is just to select suitably from well-known things, such as a germanium or a tellurium compound, and a halogenated organic phosphonium salt. Especially, quaternary phosphonium iodide or bromide is used preferably. Specific examples thereof include triphenylmethylphosphonium iodide, triphenylpropylphosphonium iodide, triphenylbenzylphosphonium iodide, tributylmethylphosphonium iodide and the like. It is preferable to supply such a carbonation catalyst to a reaction system so that it may become 0.001-0.05 mol with respect to an alkylene oxide.

In the carbonation process of this invention, not only a carbonation reaction but also the hydrolysis reaction mentioned later can be performed simultaneously. In the case of simultaneously performing the hydrolysis reaction, an alkali metal carbonate is coexisted in the reaction system as the hydrolysis catalyst. Specifically, sodium, potassium or the like, preferably potassium hydroxide, carbonate or bicarbonate may be added to the carbonation step, and any alkali metal compound is added, and these exist as carbonates in the reaction system. In this case, the alkali metal carbonate, preferably potassium carbonate, is preferably present in a molar ratio of 0.01 to 1.0 with respect to the carbonation catalyst such as quaternary phosphonium iodide. It is also preferable to add an alkali metal carbonate to the reaction system in order to maintain the concentration.

The method of this invention is characterized by including the process of removing the alkali metal chloride derived from the carbonate of the said alkali metal, or the chlorine ion derived from this alkali metal chloride from a reaction system.

Ethylene oxide, propylene oxide, etc. are used for the alkylene oxide of a raw material. As the alkylene oxide, purified alkylene oxide having a high purity may be used or a crude product may be used, but usually contains a small amount of chlorine compounds such as chlorohydrocarbons. Specifically, for example, in the case of ethylene oxide, a crude ethylene oxide having low purity containing water obtained in the production process of ethylene oxide described in WO 2004/056794 or the like can be used. The alkylene carbonate produced as a preferable aspect of the present invention is ethylene carbonate.

In the carbonation step, since water is present, the alkylene oxide is converted not only to the alkylene carbonate but also to the alkylene glycol, so that the reaction proceeds easily even at an equimolar amount of carbon dioxide or less relative to the alkylene oxide. . When performing a hydrolysis process simultaneously, it is preferable to use about 1.0-10 times mole of the quantity of the water with respect to an alkylene oxide normally with respect to an alkylene oxide. Moreover, although carbon dioxide has sufficient effect in the quantity below equimolar with respect to alkylene oxide, there is not necessarily a restriction | limiting with respect to these ratios. Preferably they are 0.1 times mole or more and 5.0 times mole or less.

Although reaction temperature of a carbonation process is 50-200 degreeC normally, it is preferable to carry out at 100 degreeC-170 degreeC. Moreover, although reaction pressure is 0.5-5.0 Mpa normally, Preferably it is implemented at 1.0-3.0 Mpa.

The carbonation reaction can be carried out using any apparatus, but it is preferable to carry out using a bubble column. As an example, the reaction temperature is controlled by circulating the reaction liquid in the tower via the liquid circulation conduit using a bubble column having a liquid circulation conduit having a heat exchanger for heat removal and a pump for circulation in the middle, and controlling the reaction temperature. Phosphorus alkylene oxide, carbon dioxide, catalyst, and water are continuously supplied as necessary to continuously carry out the reaction. Moreover, it is also preferable to use the reactor provided with the ejector type nozzle disclosed by Unexamined-Japanese-Patent No. 11-269110. Moreover, since it is inefficient to fully react an alkylene oxide in a bubble column, it is also preferable to arrange | position a tubular reactor behind a bubble column, and to further react the alkylene oxide in a liquid.

In this aspect, the reaction liquid obtained at the carbonation process is sent to a hydrolysis process. However, in some cases, part or all of the reaction solution may be sent to the production step of the alkylene carbonate to recover the alkylene carbonate. The remaining reaction liquid which collect | recovered alkylene carbonate is combined with the remaining liquid obtained at the carbonation process, and is sent to a hydrolysis process.

(2) hydrolysis process

The hydrolysis reaction is advantageously carried out at a high temperature in view of the reaction rate. However, if the temperature is too high, the alkylene glycol may be deteriorated. Therefore, the hydrolysis reaction is preferably performed at 100 to 180 ° C. Although the reaction pressure is arbitrary as long as it reaches the boiling point of a liquid, it is preferable to carry out normally at normal pressure-2.1 MPa, and also, as hydrolysis progresses, reaction temperature is made high or reaction pressure is made low, and hydrolysis is promoted. It is also preferable to make it.

The amount of water to the reaction solution obtained in the carbonation step is sufficient if the amount of the equimolar or more relative to the alkylene carbonate contained, but is preferably added in consideration of the moisture accompanying the carbonic acid gas in accordance with the progress of the hydrolysis, Usually, it is preferable to carry out 10 times mole or less, Preferably it is 1-5 times mole of the alkylene oxide used as a raw material. The method of adding water includes a method of adding in a batch at the beginning of the carbonation process, a method of adding in a hydrolysis process, a method of adding it several times depending on the progress of the reaction in a hydrolysis process, and supplying with steam. Any method may be sufficient.

Although the reactor of a hydrolysis process does not have a restriction | limiting in particular, Since carbon dioxide gas is generated with progress of reaction, it is necessary to remove the generated carbon dioxide gas. Moreover, since reaction is an endothermic reaction, in order to prevent the temperature fall, it is preferable to provide the heat exchanger for a heating. There is a method of installing a heat exchanger inside the reactor, a method of partially extracting the liquid and heating the heat exchanger installed outside, and then returning it to the reactor again. Although the reactor may be carried out in one reactor, in order to maintain the conversion ratio of the alkylene carbonate, there is a method of forming a partition inside the reactor to control the flow of the liquid or reacting using a plurality of reactors.

As the catalyst used in the hydrolysis step, the catalyst used in the carbonation step can be used as it is. If the rate of hydrolysis is insufficient, the catalyst may be added in the hydrolysis step.

(3) Recovery process (dehydration process)

The alkylene glycol produced | generated by hydrolysis can be acquired separately in a reaction liquid by a well-known method. Usually, the crude alkyl which consists of alkylene glycol, dialkylene glycol, other high boiling point components, a carbonation catalyst, etc. first through distillation in a distillation installation, Preferably it is distillation under reduced pressure and water is separated. Obtain len glycol.

(4) catalyst separation process, catalyst circulation process

In the reaction step of the present invention, the liquid containing the catalyst is circulated in one of the reaction steps after the catalyst is separated by a suitable method. Here, the process of separating a catalyst is called a catalyst circulation process, and the process of circulating the liquid containing the catalyst obtained by the catalyst separation process to a reaction process is called a catalyst circulation process.

The liquid containing the catalyst provided to a catalyst separation process is acquired at a reaction process later than a carbonation process.

As a specific catalyst separation and circulation process, when using the liquid containing the catalyst obtained by the said hydrolysis process, after dehydrating the reaction liquid of a hydrolysis process as described in (3), it supplies to a flushing tank. Most of the high boiling point such as alkylene glycol and dialkylene glycol are vaporized and separated, and the liquid containing the remaining alkylene glycol, dialkylene glycol, high boiling point and catalyst is recovered and circulated to the reaction process as a catalyst liquid. Let's do it. It is preferable to circulate the catalyst liquid here in a carbonation process. The catalyst separation is preferably carried out under reduced pressure to promote evaporation of alkylene glycol and dialkylene glycol. As the evaporation apparatus, a reboiler is used to supply energy necessary for evaporation and to control the amount of evaporation.

(5) Alkali metal chloride removal process derived from carbonate of alkali metal

In the present invention, a step of removing an alkali metal carbonate that is present as a hydrolysis catalyst is neutralized to form a chloride (in this specification, sometimes referred to as "alkali metal chloride"). do. As a method of removing the alkali metal chloride derived from the carbonate of the alkali metal, any method can be used as long as it is possible to remove the alkali metal chloride present in the reaction system. Preferably, the reaction of any of the reaction steps of the present invention. After extracting the liquid to remove the alkali metal chloride contained in the reaction liquid, a method of circulating with any of the reaction steps of the present invention is adopted. Moreover, in the method of this invention, in order to remove the chloride derived from a carbonation catalyst, you may add or may not add an inorganic bromide or an inorganic iodide.

As a reaction liquid to be extracted, it is preferable that the density | concentration of alkali metal chloride is 2 weight% or less first, in detail to 0.1 weight%-1 weight%. If the concentration of the alkali metal chloride in the extracted reaction solution is too high, chloride itself is precipitated, which is not preferable because it causes clogging problems. The reaction liquid provided in the alkali metal chloride removal treatment may be any reaction liquid after the carbonation step, but the reaction liquid obtained in the hydrolysis step during the continuous operation, or the reaction liquid obtained in the hydrolysis step, or the valence thereof. The liquid which extracted alkylene glycol and water from the reaction liquid obtained by a decomposition process (this may be called "catalyst liquid" in this specification) is mentioned.

The extraction of the reaction solution may be continuous or intermittent. In addition, although the extraction method may extract a whole quantity of reaction liquid, it is easy to process because the amount of reaction liquid which a part which extracts a part of reaction liquid processes is small.

The method for removing the alkali metal chloride from the reaction solution may be any method known per se, but specifically, at least part of the alkylene glycol contained in the reaction solution obtained above is distilled off and the distillation is performed. The method of removing the solid content precipitated in separation | separation, the method of using ion exchange resin, etc. are mentioned. The method by removing the solid content which precipitates when the alkylene glycol and high boiling point component contained in a reaction liquid are evaporated and collect | recovered below is demonstrated.

First, the extracted reaction solution is provided in a step of distilling off at least part of the alkylene glycol contained in the obtained reaction solution (hereinafter may be referred to as a "distillation step"). The distillation step is carried out until the alkali metal chloride concentration in the liquid is 0.5% by weight or more, preferably 1% by weight or more, and more preferably 2% by weight or more. In addition, although this distillation separation process distills alkylene glycol, you may isolate high boiling point components, such as dialkylene glycol and a trialkylene glycol, in order to make the alkali metal chloride concentration in a reaction liquid into the above-mentioned range.

As a specific distillation method, under reduced pressure, specifically 500 torr or less, Preferably it is 30-200 torr, The temperature which does not deteriorate a catalyst, 120-200 degreeC, It carries out at 120-180 degreeC preferably. As a distillation apparatus, the thing equipped with the reboiler is used, the energy required for evaporation is replenished, and the amount of evaporation is controlled.

Although it changes also with compositions other than alkali metal chloride, at least an alkylene glycol and the high boiling point are distilled off as needed, and alkali metal chloride precipitates out when the alkali metal chloride concentration in a liquid exceeds 0.5 weight%. The solid, precipitated alkali metal chloride, is separated from the solution portion. As a separation method, it can carry out by methods, such as filtration separation, centrifugal separation, and sedimentation separation, and any method may be used.

Specifically, for example, when sedimentation is carried out via a settling tank, in general, the lower the temperature, the lower the solubility and the higher the removal effect. However, in the present method, if too cooled, the viscosity of the catalyst solution as a solution portion is increased. Since the fluidity is elongated and the fluidity disappears, it is preferable to heat or insulate to handle at 80 degreeC or more, More preferably, it is 90 degreeC or more and 180 degrees C or less. The settling tank may be provided separately from the evaporation device, but it is preferable to flush the reaction liquid heated by the heat exchanger with the distillation device and the settling tank integrally or to flush the settling tank directly from the top.

Alkali metal chlorides, which are precipitated solids, are solid-liquid separated and recovered as a solid, or after the residual liquid in the settling tank is extracted from the drain line, the remaining alkali metal chlorides are dissolved in a solvent, and then detoxified. The treatment is preferably carried out by a method such as extraction from a manhole while being solid and detoxification treatment. In addition, the solution part separated and recovered above can be supplied as a liquid containing the catalyst which performed the above-mentioned catalyst separation process to a reactor, preferably the reactor of a carbonation process, and can be used as a catalyst (catalyst circulation process). In addition, the catalyst liquid which is the solution part after removing a solid substance can be separated and collect | recovered only as a catalyst separation process here again, and can also provide it to a catalyst circulation process. As a method for recovering the catalyst, for example, a method described in Japanese Patent No. 4273802 and the like can be mentioned.

(6) Chlorine ion removal process derived from alkali metal chloride

According to a second aspect of the present invention, a chlorine ion derived from an alkali metal chloride neutralized by an alkali metal carbonate present as a hydrolysis catalyst is also included. The method for removing chlorine ions derived from the alkali metal chloride may be any method as long as the method can remove the chlorine ions present in the reaction system. Preferably, the alkalinity of the catalyst liquid circulated in the reaction step (in the catalyst liquid The condensate described below is discharged out of the system so that the concentration of the OH group of the hydrolysis catalyst to be contained is 0.03 mol / mol or more with respect to the catalyst concentration. When the alkalinity of the catalyst liquid is 0.03 mol / mol or less with respect to the catalyst concentration, the rate of hydrolysis decreases, and it is difficult to say that it is an industrially advantageous method for producing alkylene carbonate and / or alkylene glycol. The alkalinity of the catalyst liquid is adjusted to 0.03 mol / mol or more with respect to the catalyst concentration, more preferably 0.05 mol / mol or more with respect to the catalyst concentration. The alkalinity can be measured by a known method. Specifically, it can carry out by titration with an acid regarding a catalyst liquid.

As an index for discharging the condensate out of the system, it is also possible to use a chlorine ion contained in the catalyst liquid that is less than 3 in a molar ratio with respect to the alkali metal contained.

When the molar ratio of chlorine ion concentration becomes three or more with respect to the alkali metal to contain, the alkali metal added as a hydrolysis catalyst may be neutralized and may not function as a hydrolysis catalyst. The molar ratio of chlorine ions to alkali metal in the catalyst liquid to be circulated is less than 3, preferably less than 2, most preferably less than 1. The chlorine ion concentration in the catalyst liquid to be circulated can be measured by methods commonly used, such as precipitation titration and ion chromatography.

If the molar ratio knows the discharge amount of the condensate within the above range as an empirical value, a method of discharging the amount can be taken without monitoring the chlorine ion concentration in the circulating catalyst liquid.

When the chlorine ion removal method derived from the alkali metal chloride is performed, in the method for producing alkylene carbonate and / or alkylene glycol, the gas containing carbon dioxide released in the carbonation step and / or hydrolysis step is cooled. Condensation process.

In the case of removing chlorine ion in a carbonation process, the gaseous-phase part of a reactor is cooled, a condensate is collect | recovered, it is extracted and discharged. The amount of the discharge may be any amount, and may be an amount sufficient for the alkalinity in the catalyst liquid circulated in the reaction step to be 0.03 mol / mol or more with respect to the catalyst concentration. Since the condensate contains an alkylene oxide as a raw material in addition to the chlorine ions (organic chlor compound), the alkylene oxide is recovered if necessary and then discharged as a solution containing chlorine ions (organic chlor compound).

In the case of removing chlorine ions (organic chlor compound) in the hydrolysis step, the chlorine ions (organic chlor compound) are cooled by cooling the carbon dioxide gas generated in accordance with the progress of the hydrolysis and condensing water vapor accompanying the carbon dioxide gas. Recovered in the condensate. Therefore, a method is used in which the entire amount or the alkalinity of the catalyst liquid circulating in the reaction step is extracted outside the reaction system and discharged in an amount sufficient to be 0.03 mol / mol or more relative to the catalyst concentration.

In the initial stage of operation, since the accumulation amount of chlorine ions is small and the alkalinity of the catalyst liquid is 0.03 mol / mol or more with respect to the catalyst concentration, it may be returned to the hydrolysis reactor as it is. Although extraction of a condensate may be performed after chlorine ion accumulates, it is also preferable to extract beforehand in order to prevent accumulation of chlorine ion. The extraction is preferably carried out continuously or intermittently while adjusting the extraction amount while monitoring the chlorine ion concentration in the catalyst liquid and the situation of the hydrolysis reaction. The remaining part of the condensate extracted and discharged out of the reaction system can be circulated in a carbonation step or a hydrolysis step.

The condensate extracted outside the reaction system may be disposed as it is as waste water and then disposed of after detoxification if necessary, but organic matters such as alkylene glycol are contained. . When recovering the waste water, in order to prevent the chlorine ion (organic chlor compound) from returning back to the process as chlorine, dehydration is carried out in advance, and the alkylene glycol is recovered after distilling off the organic chlor compound with water. It is preferable.

In addition, as another method for removing chlorine ions, the condensate is supplied to the hydrolysis reaction solution supply stage or the upper stage of the distillation column of the dehydration step, and the chlorine ions (organic chlor compound) are discharged from the column top simultaneously with water. Is also used. The reaction liquid coming from the hydrolysis step contains a hydrolysis catalyst. Therefore, when supplied to the stage below the feed stage, chlorine ions (organic chlor compound) may react with the hydrolysis catalyst to neutralize the hydrolysis catalyst as chlorine, and to avoid this, the hydrolysis reaction liquid It is necessary to feed to or above the feed stage of to avoid contact with the hydrolysis catalyst.

(7) Supply of catalyst

In the reaction step of the present invention, in order to continue operation while maintaining the hydrolysis reaction rate more, an alkali metal carbonate initially present as a hydrolysis catalyst may be added to the reaction step. The alkali metal carbonate to be added, preferably potassium carbonate, is preferably such that it maintains a concentration of 0.01 to 1.0 in molar ratio with respect to the carbonation catalyst such as quaternary phosphonium iodide. Although solid may be added directly as a method of adding a carbonate, the method of melt | dissolving and adding in water or melt | dissolving in alkylene glycol is effective from a handling point of view. Although addition of an alkali metal carbonate may be added continuously, operation can be continued without a problem by adding an appropriate amount when reaction rate falls, monitoring the state of a hydrolysis reaction.

In addition, when chlorine is removed, halogen or a catalyst such as iodine or bromine derived from the carbonation catalyst is removed together, a carbonation catalyst or a hydrolysis catalyst is added or, in some cases, hydrogen iodide or hydrogen bromide. It is preferable to add the hydrogen halide corresponding to the used catalyst.

(8) Purification of Alkylene Carbonate and Alkylene Glycol

The crude alkylene carbonate and / or crude alkylene glycol thus produced and recovered can be purified as needed by a commonly used method known per se.

Example

Although an Example is given to the following and this invention is demonstrated to it further more concretely, this invention is not limited by the following example, unless the summary is exceeded.

Example 1

(1) Carbonation Process

5 parts by weight of tributylmethylphosphonium iodide / Hr, 0.8 parts by weight of potassium carbonate / Hr, and raw material ethylene in a carbonation reaction portion including a carbonation reactor at 100 ° C., a residence time pressurized at 2.0 MPa with carbon dioxide. The carbonation process reaction liquid containing ethylene carbonate and ethylene glycol (EG) was obtained by supplying 78 weight part / Hr of oxide aqueous solution (60 weight%).

(2) hydrolysis process

The reaction solution obtained in the carbonation step is transferred to a hydrolysis reaction section including a hydrolysis reactor having a residence time of 2 hours, a pressure of 0.5 MPa, and a temperature of 150 ° C. Decomposition reaction reaction solution 87.5 parts by weight / Hr was obtained.

(3) Purification

The reaction solution obtained in the hydrolysis step was distilled by a reduced pressure column at a bottom of 140 ° C. and 80 torr to obtain a dehydrated liquid from the bottom of the column, which was then evaporated most of ethylene glycol by a reduced pressure evaporator operated at 140 ° C. and 60 torr. 13 parts by weight / Hr of a catalyst liquid having a concentrated catalyst was recovered from the bottom of the evaporator. The recovered catalyst solution was circulated and used as a catalyst in a carbonation reactor.

As a result of continuing the operation, since the hydrolysis reaction was insufficient, the operation was continued while adding potassium carbonate.

In the hydrolysis process which continued operation for 3 months, the reaction liquid was taken out, 100 parts of the reaction liquid was put into the glass evaporator, and the distillation operation of ethylene glycol was performed. The pressure was 30 torr, and heating was performed by heating an oil bath to 170 degreeC.

When 5 parts of ethylene glycol contained in the reaction solution was distilled off, it was confirmed that potassium chloride precipitated on the surface of the bottom flask of the evaporator. The distillation operation was continued again, and the distillation operation was stopped when the liquid containing 46 parts ethylene glycol as the main component flowed out. It was confirmed that potassium chloride precipitated at the bottom of the flask. Here, a part of the liquid containing the catalyst in the supernatant portion was extracted, and the carbonation step and the hydrolysis step were carried out in the same manner as the above as the regenerated catalyst solution from which potassium chloride was removed. Could continue further.

Comparative Example 1

In Example 1, operation was continued in the same manner as in Example 1 except that potassium chloride was not removed from the catalyst liquid. As a result, potassium chloride precipitated in the catalyst liquid, making it difficult to circulate the catalyst liquid, and the operation was stopped.

[Example 2]

(1) Carbonation Process

5 parts by weight of tributylmethylphosphonium iodide / Hr, 0.8 parts by weight of potassium carbonate / Hr, and raw material ethylene in a carbonation reaction portion including a carbonation reactor at 100 ° C., a residence time pressurized at 2.0 MPa with carbon dioxide. The carbonation process reaction liquid containing ethylene carbonate and ethylene glycol (EG) was obtained by supplying 78 weight part / Hr of oxide aqueous solution (60 weight%).

(2) hydrolysis process

The reaction solution obtained in the carbonation step is first subjected to a hydrolysis reaction of ethylene carbonate in a first hydrolysis reactor at a pressure of 1.8 MPa and a temperature of 150 ° C., followed by a second hydrolysis reactor at a pressure of 0.2 MPa and a temperature of 150 ° C. The remaining ethylene carbonate was hydrolyzed to obtain 87.5 parts by weight / Hr of a hydrolysis step reaction solution containing a catalyst and ethylene glycol. The carbon dioxide generated by the hydrolysis was cooled by a heat exchanger to condense the moisture accompanying the carbon dioxide, and then returned to the hydrolysis reactor to continue the reaction.

(3) Dehydration / chlorine ion removal process

The reaction solution obtained in the hydrolysis step was dehydrated and distilled by a reduced pressure column at 140 ° C. and 80 torr to obtain a liquid dehydrated from the bottom. This was again removed by a reduced pressure evaporator operated at 140 ° C. and 60 torr. By evaporation, 13 parts by weight / Hr of the catalyst liquid with concentrated catalyst was recovered from the bottom of the evaporator. The recovered catalyst solution was circulated and used as the catalyst in the first hydrolysis reactor.

After the operation was continued, the carbon dioxide gas generated in the first hydrolysis reactor was cooled and the condensate of water vapor accompanying the carbon dioxide was analyzed. As a result, 167 ppm of ethylene chlorhydrin and 273 ppm of chlormethyldioxolane were found in the condensate. Ethylene glycol was contained 17.2 wt%. There, the extraction was started continuously for the entire amount of the condensate.

It operated for 100 days and evaluated using the alkalinity which is an index of the hydrolysis rate. The said alkalinity was measured by titrating the number-of-moles of the OH group used as the hydrolysis catalyst contained in the catalyst liquid circulated by a carbonation process with an acid. In addition, in order to remove the influence by the change of the density | concentration of a catalyst liquid, it is the value divided by the number-of-moles of tributylmethyl phosphonium iodide. This result is shown in FIG. As shown in FIG. 1, the fall of the reaction rate of a hydrolysis reaction was not seen, and the alkalinity of the said catalyst liquid maintained 0.03 mol / mol or more with respect to catalyst concentration.

In addition, the concentration of chlorine ions and potassium contained in the catalyst solution were measured. The measuring method of potassium is ICP (Inductively Coupled Plasma) emission spectroscopy. The measurement method of chlorine ion is precipitation titration analysis. This result is shown in Table 1 and FIG. As can be seen from Table 1 and FIG. 2, the chlorine ion concentration contained in the catalyst liquid was less than 3 in molar ratio with respect to the alkali metal concentration.

[Example 3]

The distillation was carried out in the distillation column of the theoretical stage 8 together with the condensate and the hydrolysis reaction solution extracted in Example 2, and ethylene chlorhydrin and chlormethyldioxolane were distilled off from the top of the column together with water, and at the bottom of the column. Ethylene glycol, which did not contain an organic chlor compound, was recovered.

Comparative Example 2

Ethylene glycol was produced in the same manner as in Example 2 except that the condensate of water vapor accompanying the carbon dioxide gas obtained by cooling the carbon dioxide gas generated in the first hydrolysis reactor was supplied to the hydrolysis step as it was. The operation was continued for 230 days, and the alkalinity of the hydrolysis catalyst in the catalyst liquid circulated in the carbonation step was measured in the same manner as in Example 2. This result is shown in FIG. As can be seen from FIG. 3, the alkalinity of the hydrolysis catalyst decreases, and the reaction rate of the hydrolysis reaction gradually slows down to 98.8% that the conversion rate of ethylene carbonate was 99.9% or more.

Industrial availability

According to the method of the present invention, a method for producing alkylene carbonate and / or alkylene glycol which can stably operate for a long period of time without preventing the catalyst from deteriorating in the hydrolysis step and maintaining the hydrolysis rate without generating precipitates in the reaction system is provided. Is provided. By employing this method, it is possible to produce alkylene carbonate and / or alkylene glycol efficiently and with low loss.

Claims (10)

In the presence of a catalyst and an alkali metal carbonate, alkylene carbonate, water and carbon dioxide are reacted to produce alkylene carbonate and / or alkylene glycol, and alkylene carbonate and / or from the reaction liquid obtained in the reaction step. In the manufacturing method of the alkylene carbonate and / or alkylene glycol provided with the process of collect | recovering alkylene glycol and the catalyst circulation process which circulates the catalyst liquid containing a catalyst to a reaction process,
A method for producing an alkylene carbonate and / or alkylene glycol, comprising the step of removing an alkali metal chloride derived from the carbonate of the alkali metal or a chlorine ion derived from the alkali metal chloride in the reaction solution. The method of claim 1,
The step of removing the alkali metal chloride derived from the carbonate of the alkali metal in the reaction solution acquires a part or whole amount of the reaction solution containing the catalyst in the reaction step and distills at least a part of the alkylene glycol contained in the reaction solution. To separate and precipitate solids in the distillation, and the catalyst circulating step circulates the residual liquid from which the solids precipitated in the distillation is circulated to the reaction step. Method for producing lene glycol. The method of claim 1,
The step of removing the alkali metal chloride derived from the carbonate of the alkali metal in the reaction solution acquires a part or whole amount of the reaction solution containing the catalyst in the reaction step and distills at least a part of the alkylene glycol contained in the reaction solution. Separating and further separating the solids precipitated in the distillation separation, and after the catalyst circulating step separates and recovers the catalyst from the residual liquid from which the solids precipitated in the distillation separation, the recovered catalyst is A process for producing alkylene carbonate and / or alkylene glycol, which is circulated in a reaction step. The method according to claim 2 or 3,
Separation of the precipitated solid is carried out at 80 ℃ or more, characterized in that the alkylene carbonate and / or alkylene glycol production method. The method of claim 1,
In the reaction step, in the presence of a catalyst and an alkali metal carbonate, an alkylene carbonate is formed by reacting an alkylene oxide with carbon dioxide to produce an alkylene carbonate, and an alkylene glycol by hydrolyzing the alkylene carbonate in the reaction solution of the carbonation step. A hydrolysis process for producing
The removal process of the chlorine ion derived from the said alkali metal chloride,
The condensation step of cooling the gas containing carbon dioxide released in the carbonation step and / or the hydrolysis step, and the alkalinity of the catalyst liquid circulated from the catalyst circulation step to the reaction step is 0.03 mol / mol or more with respect to the catalyst concentration. A method for producing alkylene carbonate and / or alkylene glycol, comprising the step of discharging the condensate obtained in the condensation step. The method of claim 5, wherein
The method for producing alkylene carbonate and / or alkylene glycol in the chlorine ion removal step, wherein the condensate is dehydrated again to remove water and organic chlor compound contained therein and then the remaining liquid is circulated to the reaction step. The method according to claim 6,
A method for producing alkylene carbonate and / or alkylene glycol, wherein the organic chlor compound is ethylene chlorhydrin. 8. The method according to any one of claims 5 to 7,
Production of alkylene carbonate and / or alkylene glycol, wherein the condensate is circulated is a hydrolysis reaction solution supply stage or a stage above the distillation column for distilling water contained in the hydrolysis reaction liquid obtained in the hydrolysis step. Way. The method according to any one of claims 1 to 8,
A method for producing an alkylene carbonate and / or an alkylene glycol, wherein the alkali metal carbonate is further added to the reaction step. 10. The method according to any one of claims 1 to 9,
A method for producing alkylene carbonate and / or alkylene glycol wherein alkylene carbonate is ethylene carbonate and alkylene glycol is ethylene glycol.

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