JP6916364B1 - Method for producing metaboric acid and method for producing secondary alcohol using the metaboric acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means capable of stably producing metaboric acid. I) Orthoboric acid is dehydrated in a dehydrator in the presence of a saturated aliphatic hydrocarbon to obtain a mixture containing metaboric acid, a saturated aliphatic hydrocarbon and water; ii) The saturated aliphatic hydrocarbon and water. Is distilled off from the mixture, and then the saturated aliphatic hydrocarbon and water are separated; iii) The saturated aliphatic hydrocarbon separated in the above ii) is returned to the above i), and in the above i). , A method for producing metaboric acid, wherein the content of the alcohol component in the saturated aliphatic hydrocarbon is less than 2% by mass. [Selection diagram] None

Description

The present invention relates to a method for producing metaboric acid and a method for producing a secondary alcohol using the metaboric acid.

Higher secondary alcohol ethoxylates are widely used as nonionic surfactants because they have a low pour point and are easy to handle. This secondary alcohol ethoxylate is produced by adding an alkylene oxide using a secondary alcohol as a starting material. In the secondary alcohol, the raw material saturated aliphatic hydrocarbon is oxidized in the presence of metaboric acid, the free alcohol in the oxidation reaction product is orthoboric acid esterified, and the unreacted saturated aliphatic hydrocarbon is recovered by distillation. It is obtained by a boric acid oxidation method in which the distillation residue is hydrolyzed, the obtained organic layer is saponified with an alkali, and then the crude alcohol layer is purified (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 56-131531

There is a demand for a technique capable of stably producing metaboric acid used as a raw material in the above boric acid oxidation method.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a means capable of stably producing metaboric acid.

The present inventors have conducted diligent research in order to solve the above problems. As a result, they have found that the above problems can be solved by controlling the amount of alcohol components contained in the saturated aliphatic hydrocarbon when dehydrating orthoboric acid in the presence of the saturated aliphatic hydrocarbon, and completed the present invention.

That is, the above objectives are: i) dehydrate orthoboric acid in the presence of saturated aliphatic hydrocarbons with a dehydrator to obtain a mixture containing metaboric acid, saturated aliphatic hydrocarbons and water; ii) said saturated aliphatic hydrocarbons. And after distilling water from the mixture, the saturated aliphatic hydrocarbon and the water are separated; iii) the saturated aliphatic hydrocarbon separated in the ii) is returned to the i). ), The content of the alcohol component in the saturated aliphatic hydrocarbon is less than 2% by mass, which can be achieved by the method for producing metaboric acid.

According to the present invention, metaboric acid can be stably produced.

FIG. 1 is a schematic view of the reactor used in Example 1. FIG. 2 is a schematic diagram illustrating a secondary alcohol production process. FIG. 3 is a schematic diagram for explaining a preferable form of the oxidation reaction step (a-1).

Hereinafter, embodiments according to one embodiment of the present invention will be described. The present invention is not limited to the following embodiments.

In the present specification, "X to Y" indicating a range includes X and Y and means "X or more and Y or less". Unless otherwise specified, the operation and physical properties are measured under the conditions of room temperature (20 to 25 ° C.) / relative humidity of 40 to 50% RH.

<Manufacturing method of metaboric acid>
One embodiment of the present invention is i) dehydrating orthoboric acid in the presence of a saturated aliphatic hydrocarbon with a dehydrator to obtain a mixture containing metaboric acid, a saturated aliphatic hydrocarbon and water (step (i)); ii. ) After distilling off a part of the saturated aliphatic hydrocarbon and water from the mixture, the saturated aliphatic hydrocarbon and water are separated (step (ii)); iii) the saturated aliphatic separated in the above ii). The hydrocarbon is returned to i) (step (iii)), and in i), the content of the alcohol component in the saturated aliphatic hydrocarbon is less than 2% by mass of the metaboric acid. It is a manufacturing method (first aspect).

As a method for producing a secondary alcohol, a) a saturated aliphatic hydrocarbon is liquid-phase oxidized with a molecular oxygen-containing gas in the presence of metaboric acid to obtain a reaction solution containing an oxide (step (a-). 1)), the oxide is esterified to obtain a reaction solution containing a borate compound (step (a-2)) (the steps (a-1) and (a-2) are collectively referred to as "step (a-2)". ) ”, B) The reaction solution containing the borate compound is distilled to separate it into unreacted saturated aliphatic hydrocarbons and distillation residue (step (b)), and c) the distillation residue is hydrated. It is decomposed and separated into an aqueous layer containing orthoboric acid and an organic layer (step (c)), and d) the organic layer is saponified with an alkali and separated into an alkaline aqueous solution layer and a crude alcohol layer (step (step (step)). d)), e) Purification of the crude alcohol layer (step (e)) is performed. In the above method, unreacted saturated hydrocarbons can be recovered from several steps (for example, step b above), and it is useful in the process to reuse the unsaturated hydrocarbons in the reaction system (for example, step b above). For example, Japanese Patent Application Laid-Open No. 56-131531). Therefore, when orthoboric acid is dehydrated with a dehydrator in the presence of saturated aliphatic hydrocarbons to produce metaboric acid, the unreacted saturated aliphatics recovered in the process of producing the secondary alcohol as described above. We tried to reuse hydrocarbons (recovered saturated aliphatic hydrocarbons), but if only the recovered unreacted saturated aliphatic hydrocarbons were used as they were in the reaction, deposits would be generated on the inner walls and pipes, resulting in production. It was not possible to stably produce hydrocarbons due to reduced efficiency and equipment troubles. The present inventors have diligently studied a stable metaboric acid production process by various methods. As a result, the alcohol contained in the unreacted saturated aliphatic hydrocarbon (recovered saturated aliphatic hydrocarbon) recovered in the secondary alcohol production process (for example, after the oxidation reaction) causes the borate compound as a deposit. I guessed it was to generate. Therefore, as a result of diligent studies on the alcohol content in the saturated aliphatic hydrocarbon used for the production of metaboric acid, the alcohol content in the saturated aliphatic hydrocarbon used for the dehydration reaction of orthoboric acid was set to 2. It has been found that the formation of borate compounds, which cause deposits, can be suppressed or prevented by controlling the content to less than% by mass. According to the above method, since deposits do not adhere to the inner wall of the reactor and the pipe during the dehydration reaction, it is possible to effectively prevent an increase in stirring power and blockage of the pipe. Therefore, according to the above method, metaboric acid can be stably produced. On the other hand, when the unreacted hydrocarbon recovered by the method described in Patent Document 1 is circulated in the dehydration reaction, deposits are attached to the inner wall of the reactor and the pipe, which increases the stirring power and the pipe. May cause obstruction. This is because the recovered unreacted saturated aliphatic hydrocarbon contains an alcohol in which at least one hydrogen atom of the saturated aliphatic hydrocarbon is substituted with a hydroxyl group in a proportion of 2% by mass or more, so that this alcohol is used in the dehydration step. It is presumed that it reacts with orthoboric acid to form a borate compound, which causes deposits. It should be noted that the mechanism for exerting the above-mentioned effects and effects according to the configuration of the present invention is an estimation, and the present invention is not limited to the above estimation.

Hereinafter, each step of the first aspect will be described.

(Step (i))
In this step, a dehydrator is charged with a saturated aliphatic hydrocarbon (in the present specification, the saturated aliphatic hydrocarbon is also simply referred to as “hydrocarbon”) and orthoboric acid to prepare a slurry, and the saturated aliphatic hydrocarbon is prepared. Dehydrate orthoboric acid in the presence of hydrogen. This produces metaboric acid, resulting in a mixture (slurry) containing metaboric acid, saturated aliphatic hydrocarbons and water and, in some cases, unreacted orthoboric acid.

In this step, the content of the alcohol component in the saturated aliphatic hydrocarbon (raw material saturated aliphatic hydrocarbon) charged is less than 2% by mass. When the content of the alcohol component in the raw material saturated aliphatic hydrocarbon is 2% by mass or more, a borate compound is generated during the dehydration reaction of orthoboric acid, which induces the formation of deposits on the inner wall of the reactor and the inner wall of the pipe. However, metaboric acid cannot be produced stably. From the viewpoint of producing more stable metaboric acid, the content of the alcohol component in the saturated aliphatic hydrocarbon is preferably 1.5% by mass or less, particularly preferably less than 1% by mass (lower limit: 0% by mass or detection limit). Below). That is, in a preferred embodiment of the present invention, in i), the content of the alcohol component in the saturated aliphatic hydrocarbon is 1.5% by mass or less. In a more preferable embodiment of the present invention, in i), the content of the alcohol component in the saturated aliphatic hydrocarbon is less than 1% by mass. In the present specification, the content of the alcohol component in the saturated aliphatic hydrocarbon adopts the value measured by gas chromatography. The above-mentioned "alcohol component" refers to an alcohol (mixture) in which a hydrogen atom of a saturated aliphatic hydrocarbon having 6 to 30 carbon atoms is substituted with a hydroxyl group. The "alcohol component" is preferably a mixture containing an alcohol in which the hydrogen atom of a saturated aliphatic hydrocarbon having 8 to 20 carbon atoms is substituted with a hydroxyl group as a main component, and more preferably a saturated fat having 10 to 15 carbon atoms. A mixture containing an alcohol in which the hydrogen atom of a group hydrocarbon is substituted with a hydroxyl group as a main component, particularly preferably a mixture containing an alcohol in which a hydrogen atom of a saturated aliphatic hydrocarbon having 12 to 14 carbon atoms is substituted with a hydroxyl group as a main component. Intended.

Here, the saturated aliphatic hydrocarbon is a mixture of saturated aliphatic hydrocarbons (normal paraffin) having 8 to 30 carbon atoms. Preferably, the saturated aliphatic hydrocarbon contains a saturated aliphatic hydrocarbon having 10 to 15 carbon atoms (n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane and n-pentadecane) as a main component. It is a mixture containing, more preferably a saturated aliphatic hydrocarbon having 12 to 14 carbon atoms (n-dodecane, n-tridecane and n-tetradecane) as a main component. Here, "containing a saturated aliphatic hydrocarbon as a main component" means that a saturated aliphatic hydrocarbon having a predetermined carbon number is contained in an amount of more than 90% by mass (preferably more than 95% by mass) with respect to the total saturated aliphatic hydrocarbon. It means that it is contained in a ratio of (upper limit: 100% by mass). The average molecular weight of the saturated aliphatic hydrocarbon is 114 or more and 422 or less, preferably 142 or more and 212 or less, and more preferably 170 or more and 198 or less. Saturated aliphatic hydrocarbons may be synthetic or commercially available. Similarly, orthoboric acid may be synthetic or commercially available.

In the present disclosure, the mixing ratio of the saturated aliphatic hydrocarbon and orthoboric acid is not particularly limited, and the same mixing ratio as before can be applied. Specifically, the mixing ratio of saturated aliphatic hydrocarbon and orthoboric acid (saturated aliphatic hydrocarbon: mixed mass ratio of orthoboric acid) is 0.5 to 5: 1, preferably more than 1: 1. It is less than 3: 1. The amount of orthoboric acid added is, but is not limited to, 15 to 90% by mass, preferably more than 25% by mass and less than 45% by mass in the mixture (slurry).

In the present disclosure, the dehydration conditions for orthoboric acid in the presence of saturated aliphatic hydrocarbons are not particularly limited, and the same conditions as before can be applied in the same manner. For example, the dehydration temperature is 100 ° C. or higher and lower than 200 ° C., preferably 130 ° C. or higher and 180 ° C. or lower. The dehydration time is the time at which substantially all orthoboric acid is converted to metaboric acid, and other conditions (for example, the amount of orthoboric acid charged, the mixing ratio of saturated aliphatic hydrocarbons and orthoboric acid, the dehydration temperature, etc.) ) Can be selected as appropriate. The dehydration time is, for example, 3 to 7 hours, preferably 4 to 6 hours. If the dehydration time is within the above range, the dehydration can proceed appropriately and metaboric acid can be efficiently produced. Alternatively, the amount of metaboric acid produced in the reactor is periodically measured to determine whether substantially all orthoboric acid has been converted to metaboric acid, and the dehydration reaction occurs when the desired amount of metaboric acid is produced. May be terminated. Here, "substantially all orthoboric acid is converted to metaboric acid" means that the amount of orthoboric acid charged is more than 0.9 mol (preferably more than 0.95 mol) (upper limit: 1). It means that metaboric acid (molar) is converted. The amount of metaboric acid in the mixture can be measured by known methods. In the present specification, the amount of metaboric acid adopts the value measured by the X-ray crystal structure analysis.

The dehydration reaction may be carried out under atmospheric pressure, pressurization or reduced pressure, but is usually carried out under atmospheric pressure. Further, the dehydration reaction may be carried out with stirring (the reactor may be provided with a stirrer). Here, the stirring speed when the dehydration reaction is carried out while stirring is not particularly limited, but is, for example, 20 to 100 rpm, preferably 30 to 60 rpm. At such a stirring speed, the raw materials (saturated aliphatic hydrocarbon and orthoboric acid) can be mixed uniformly (the dehydration reaction can be carried out homogeneously).

The dehydrator (reactor for carrying out the dehydration reaction) may be made of any material. Specific examples thereof include iron, copper, stainless steel (SUS), nickel alloys (for example, Hastelloy), Inconel, titanium, and titania. Of these, stainless steel (SUS), nickel alloy (for example, Hastelloy), and titania are preferable, and stainless steel (SUS) and nickel alloy (for example, Hastelloy) are more preferable. As described in detail below, orthoboric acid separated after the hydrolysis step in the production of secondary alcohols can be reused in this step. In this case, orthoboric acid contains an organic substance (organic acid such as fatty acid, fatty acid ester, fatty acid sodium, fatty acid potassium, organic acid salt, organic acid ester, etc.), but this organic substance evaporates during the dehydration reaction, and the dehydrator May cause corrosion. Therefore, it is preferable that at least the vapor phase portion of the reactor is formed of a nickel alloy, particularly Hastelloy having excellent heat resistance, pressure resistance and corrosion resistance. That is, in the preferred embodiment of the present disclosure, at least the vapor phase portion of the dehydrator is formed of nickel alloy. In a more preferred embodiment of the present disclosure, at least the gas phase portion of the dehydrator is formed of Hastelloy. Also, in the preferred embodiment of the present disclosure, the entire dehydrator is made of nickel alloy (more preferably Hastelloy). Here, as Hasteloy, Hasteloy C-22 (composition: Ni 57.0% by mass, Cr 20.5% by mass, Mo 14.2% by mass, Fe 2.3% by mass, W: 3.2% by mass, V 0.25% by mass, C 0.01% by mass), Hasteloy C-276 (composition: Ni 57.0% by mass, Cr 15.5% by mass, Mo 16.0% by mass, Fe 6.0% by mass, W: 4.0% by mass, V 0.3% by mass, C 0.01% by mass) and the like. Also, the "gas phase portion of the dehydrator" is intended to be the portion of the dehydrator that is in contact with at least one vapor of saturated aliphatic hydrocarbons, orthoboric acid, water and metaboric acid. Specifically, the gas phase portion of the dehydrator is preferably in the range from the top of the dehydrator to 60% (more preferably 30% or more and 60% or less, particularly in the range of 30% or more and 60% or less) with respect to the total height of the dehydrator. It is preferably a portion up to 40% or more and 50% or less). That is, in a preferred embodiment of the present invention, the range from the top of the dehydrator to 60% (more preferably 30% or more and 60% or less, particularly preferably 40% or more and 50) with respect to the total height of the dehydrator. % Or less range) is formed of nickel alloy. Further, the present invention is a reactor for producing metaboric acid, in a range from the top of the reactor to 60% with respect to the total height of the reactor (preferably in a range of 30% or more and 60% or less). More preferably, a reactor in which 40% or more and 50% or less) is formed of a nickel alloy is also provided. Further, "the dehydrator is formed of the material A" includes a form in which the dehydrator is formed of the material A and a form in which the inner surface of the dehydrator formed of the material B is covered with the material A. .. That is, for example, "at least the gas phase part of the dehydrator is formed of nickel alloy" is a form in which the entire dehydrator is formed of nickel alloy; The form in which the inner wall of the phase portion is coated with nickel alloy by spraying or lining, etc .; includes the form in which the entire inner wall of the dehydrator made of another material (for example, stainless steel) is coated with nickel alloy by spraying or lining, etc. do.

In this step, orthoboric acid is intramolecularly dehydrated in the presence of saturated aliphatic hydrocarbons and converted to metaboric acid by the following reaction. Metaboric acid has α-type and β-type depending on its crystal structure, but β-type metaboric acid is preferable from the viewpoint of thermal stability (anti-clocking effect) and the like. Such β-type metaboric acid can be produced by the method described in Japanese Patent Publication No. 48-37242 and the preferable dehydration conditions as described above.

(Step (ii))
In this step, the saturated aliphatic hydrocarbon and water are distilled off from the dehydration reaction product obtained in the above step (i), and then the saturated aliphatic hydrocarbon and water are separated.

During the dehydration step of step (i) above, saturated aliphatic hydrocarbons and water evaporate (mixed vapors of saturated aliphatic hydrocarbon vapors and water vapor are generated). These mixed vapors are extracted from the dehydration reactor and separated. Here, the method for separating the saturated aliphatic hydrocarbon and water in the mixed vapor is not particularly limited. For example, these vapors are extracted from the upper part of the dehydrator to the outside of the system, the vapors extracted from the system are condensed into a liquid, and the condensate is separated into an aqueous layer (water) and an organic layer (saturated) in a settler (separation tank). There is a method of separating into aliphatic hydrocarbons). Of the aqueous layer (water) and the organic layer (saturated aliphatic hydrocarbon) separated in this way, water is extracted from the system.

(Step (iii))
In this step, the saturated aliphatic hydrocarbon separated in the step (ii) is returned to the step (i).

Most of the saturated aliphatic hydrocarbons separated in this step contain alcohol components (alcohol components in which at least one hydrogen atom of the saturated aliphatic hydrocarbon is replaced with a hydroxyl group) that produces a borate compound that causes deposits. Not included or not included at all. Therefore, even if the saturated aliphatic hydrocarbon evaporated during the dehydration reaction of orthoboric acid is used in the dehydration reaction of orthoboric acid, the alcohol component reacts with orthoboric acid to form a borate compound with little or no. Therefore, it is possible to effectively prevent the formation of deposits on the inner wall of the reactor and the pipe, and therefore the increase in the stirring power and the blockage of the pipe. Therefore, according to the method of the present disclosure, metaboric acid can be stably produced. Further, since it is not necessary to add fresh hydrocarbon separately, it is preferable from the viewpoint of production cost and the like. Here, the content of the alcohol component in the saturated aliphatic hydrocarbon separated in the above step (ii) is preferably less than 2% by mass in the saturated aliphatic hydrocarbon separated in the above step (ii), and more. It is preferably 1.5% by mass or less, particularly preferably less than 1% by mass (lower limit: 0% by mass or detection limit or less).

<Manufacturing method of secondary alcohol>
As described above, according to the method of the present disclosure, metaboric acid can be suitably produced in a stable manner and at a low production cost. Therefore, the metaboric acid produced by the present disclosure can be suitably used for the production of secondary alcohols. That is, in the present invention, a) a reaction solution containing a borate compound is obtained by hydrolyzing and esterifying a saturated aliphatic hydrocarbon with a gas containing molecular oxygen in the presence of metaboric acid; b) the borate compound. The contained reaction solution is distilled to separate it into unreacted saturated aliphatic hydrocarbons and distillation residue; c) The distillation residue is hydrolyzed and separated into an aqueous layer containing orthoboric acid and an organic layer; d. ) The organic layer is hydrolyzed with an alkali to separate it into an aqueous alkali layer and a crude alcohol layer; e) the crude alcohol layer is purified to obtain a secondary alcohol, which is secondary. A method (second aspect) of the method for producing an alcohol, wherein the metaboric acid is produced using the method of the present disclosure in the step a) is also provided.

Hereinafter, each step of the second aspect will be described. In the second aspect, c) orthoboric acid separated in the hydrolysis step is used in the dehydration step of the first aspect to produce metaboric acid, and this metaboric acid is circulated in the step a) of the second aspect. The other steps can be applied in the same manner as the conventionally known steps or with appropriate modifications.

(Step (a))
In this step, metaboric acid, saturated aliphatic hydrocarbons and molecular oxygen-containing gas (reaction gas containing molecular oxygen; the same applies hereinafter) are supplied to the reactor, and saturated aliphatic hydrocarbons are provided in the presence of metaboric acid. Hydrocarbon is liquid-phase oxidized with a molecular oxygen-containing gas to obtain a reaction solution containing an oxide (oxidation reaction step (a-1)). Next, the oxide obtained above is esterified to obtain a reaction solution containing a borate compound (esterification step (a-2)). That is, the following reaction occurs in this step.

The metaboric acid used in the above step (a-1) is produced by using the method of the present disclosure.

In the above step (a-1), the molecular oxygen-containing gas contains nitrogen gas and the like in addition to the molecular oxygen (oxygen). Preferably, the molecular oxygen-containing gas is composed of molecular oxygen (oxygen) and nitrogen gas. The concentration of molecular oxygen (oxygen) in the molecular oxygen-containing gas is 1% by volume (vol%) or more and 10% by volume (vol%) or less, preferably 3% by volume (vol%) or more and 5% by volume (vol%) or more. Vol%) or less, but not limited to this. The supply amount of the molecular oxygen-containing gas is, but is not limited to, 100 to 1000 liters / hour, preferably 350 to 600 liters / hour, etc. per 1000 g of saturated aliphatic hydrocarbon.

In the above step (a-1), the reaction mixing ratio of metaboric acid and saturated aliphatic hydrocarbon is not particularly limited, but metaboric acid is preferably 1% by mass or more and 5% by mass with respect to saturated aliphatic hydrocarbon. Hereinafter, it is more preferably 2% by mass or more and 4% by mass or less, and the like, but the present invention is not limited thereto.

The liquid phase oxidation reaction conditions are not particularly limited, and the same conditions as before can be applied in the same manner. For example, the liquid phase oxidation reaction temperature is, but is not limited to, 100 to 250 ° C., preferably 140 to 200 ° C. and the like. The liquid phase oxidation reaction time is, for example, 0.5 to 5 hours, preferably 1 to 3 hours, and the like, but is not limited thereto. Under such conditions, the saturated aliphatic hydrocarbon can be liquid-phase oxidized with a molecular oxygen-containing gas within an appropriate range (for example, conversion rate of saturated aliphatic hydrocarbon = 5 to 30%). The liquid phase oxidation reaction may be carried out under atmospheric pressure (normal pressure), pressure or reduced pressure, but is usually carried out under atmospheric pressure (normal pressure) to 30 kg / cm ² G. Further, the liquid phase oxidation reaction may be carried out with stirring (the reactor may be provided with a stirrer).

In the above step (a-1), the liquid phase oxidation reaction may be carried out in one reactor or continuously in a plurality of two or more reactors. Further, the reactor may be, for example, a stirring tank type or a bubble tower type.

In the above step (a-1), the liquid phase oxidation reaction may be carried out in any form, but the liquid phase oxidation reactor comprises two or more reactors that can be switched between a batch type and a continuous type. It has the addition of saturated aliphatic hydrocarbons to each of the two or more reactors, the addition of metaboric acid to the most upstream reactor of the two or more reactors, and the most upstream of the above. Starting to obtain the oxide in a batch system at the reactor on the side, monitoring the difference in oxygen concentration at the inlet and outlet of the reactor on the most upstream side is performed so that the difference in oxygen concentration is 0.5% by volume or more. When it becomes, it is preferable to switch to the continuous type. According to the above method, it is possible to provide a method for starting up a continuous system having good reactivity, that is, good production efficiency, and by extension, it is possible to provide a method for producing a secondary alcohol having good production efficiency. That is, in a preferred embodiment of the present invention, a-1) metaboric acid, saturated aliphatic hydrocarbon and molecular oxygen-containing gas (reaction gas containing molecular oxygen) are supplied to the reactor, and the presence of metaboric acid is present. Below, the saturated aliphatic hydrocarbon is liquid-phase oxidized with a molecular oxygen-containing gas (reaction gas containing molecular oxygen) to obtain a reaction solution containing an oxide, and a-2) the oxide is esterified. To obtain a reaction solution containing a borate compound, b) distill the reaction solution containing the borate compound to separate it into unreacted saturated aliphatic hydrocarbons and a distillation residue, and c) hydrolyze the distillation residue. Then, it is separated into an aqueous layer containing orthoboric acid and an organic layer, and d) the organic layer is hydrolyzed with an alkali to separate it into an alkaline aqueous solution layer and a crude alcohol layer, and e) the crude alcohol layer. Is a method for producing a secondary alcohol, which comprises purifying a secondary alcohol, wherein the metaboric acid is produced using the method of the present invention, and the reactor is made into a batch type and a continuous type. It consists of two or more switchable reactors, each of which has the addition of saturated aliphatic hydrocarbons to each of the two or more reactors, and metahoose to the most upstream reactor of the two or more reactors. With the addition of an acid, the oxide is started to be obtained in a batch manner in the most upstream reactor, and the difference in oxygen concentration at the inlet and outlet of the most upstream reactor is monitored. It is a method for producing a secondary alcohol, which comprises switching to a continuous type when the oxygen concentration difference becomes 0.5% by volume or more.

Hereinafter, the preferred embodiment will be described. In the following, since metaboric acid is produced in the same manner as described above, description thereof will be omitted here. Further, the present invention is not limited to the following preferred forms.

In the step (a-1), the reactor comprises two or more reactors that can be switched between a batch type and a continuous type, and saturated aliphatic hydrocarbons are added to each of the two or more reactors. To have metaboric acid added to the most upstream reactor of the two or more reactors, and to start obtaining the oxide in a batch manner in the most upstream reactor. It is possible to monitor the oxygen concentration difference at the inlet and outlet of the most upstream reactor and switch to the continuous system when the oxygen concentration difference becomes 0.5% by volume or more.

FIG. 3 is a schematic view showing a reactor capable of measuring oxygen concentration. As shown in FIG. 3, the (plural) reactors 30 are composed of two reactors (41, 42). The volume of the most upstream reactor (reactor 41 in FIG. 3) and, if necessary, one or more reactors (reactor 42 in FIG. 3) may be appropriately determined according to the production amount of the target product. The two reactors (41, 42) can be switched between a batch type and a continuous type by being connected by a pipe 32. Each reactor (41, 42) has an inlet 33 into which saturated aliphatic hydrocarbons and metaboric acid are added, an inlet 34 into which a molecular oxygen-containing gas (reaction gas containing molecular oxygen) is introduced, and a molecule. It is provided with an outlet 35 from which a gas containing oxygen (reaction gas containing molecular oxygen) is discharged.

In one embodiment of the invention, the reaction gas comprises molecular oxygen. In addition, it may contain ammonia and the like. The reaction gas, together with the circulating gas, can be introduced into each reactor (41, 42) via the inlet 34. Examples of the circulating gas include an inert gas, and for example, nitrogen gas and the like are suitable. In one embodiment of the invention, the concentration of ammonia in the reaction gas can be 10% to 1000% by volume.

In the present preferred embodiment, the inlet 34 and the outlet 35 of each reactor (41, 42) are provided with measuring instruments capable of measuring the oxygen concentration (not shown). The inlet 34 and the outlet 35 each consist of a gas pipe. In the present preferred embodiment, the inlet 34 (gas pipe) and the outlet 35 (gas pipe) of the reactor 41 are each provided with a measuring instrument capable of measuring one oxygen concentration, and the inlet 34 (gas pipe) and the outlet of the reactor 42 are provided. Each of the 35 (gas pipes) is provided with a measuring device capable of measuring one oxygen concentration, and each 35 (gas pipe) is provided with a measuring device capable of measuring one oxygen concentration.

By providing such a measuring instrument, it is possible to monitor the difference in oxygen concentration between the inlet 34 and the outlet 35. To put it plainly, the fact that the concentration of oxygen entering from the inlet 34 is low at the outlet 35 means that the oxidation reaction is proceeding. In this preferred embodiment, the difference in oxygen concentration at the inlet and outlet of the most upstream reactor (reactor 41 in FIG. 3) and optionally one or more other reactors (reactor 42 in FIG. 3). When the difference in oxygen concentration becomes 0.5% by volume or more after monitoring, the system is switched to the continuous system. In the present preferred embodiment, the oxygen concentration difference at the inlet and outlet of each of the two or more reactors is monitored, and when the oxygen concentration difference becomes 0.5% by volume or more, the system is switched to the continuous type. Here, if the difference in oxygen concentration is less than 0.5% by volume, the reactivity of the oxidation reaction in the continuous formula deteriorates, and it is not possible to provide a method for producing a secondary alcohol having good production efficiency. In the present specification, the oxygen concentration difference can be calculated by (oxygen concentration at the inlet (volume%))-(oxygen concentration at the outlet (volume%)).

In this preferred embodiment, the oxygen concentration differences at the inlet and outlet of the most upstream reactor (reactor 41 in FIG. 3) and one or more other reactors (reactor 42 in FIG. 3) are independent of each other. Then, it is 0.5% by volume or more (preferably 1.0% by volume or more). In one embodiment of the present invention, the difference in oxygen concentration at the inlet and outlet of the most upstream reactor (reactor 41 in FIG. 3) and one or more other reactors (reactor 42 in FIG. 3) is different, respectively. Independently, it is 10% by volume or less (preferably 5.0% by volume or less). By such an embodiment, the oxidation reaction can be stably carried out.

In this preferred embodiment, saturated aliphatic hydrocarbons are added to each reactor (reactors 41 and 42 in FIG. 3) via the inlet 33.

In this preferred embodiment, metaboric acid is added to the reactor on the most upstream side of the reactor (reactor 41 in FIG. 3). In one embodiment of the present invention, metaboric acid is less than 10% by mass, 7% by mass or less, 5% by mass or less, based on the saturated aliphatic hydrocarbon contained in the reactor on the most upstream side of the reactor (reactor 41 in FIG. 3). Add at a concentration of 7% by mass or less, or 3% by mass or less. When metaboric acid is added to the reactor at a concentration of 10% by mass or more, there is a possibility that the oxygen concentration difference at least at the inlet and outlet of the most upstream reactor cannot be 0.5% by volume or more. In the present preferred embodiment, metaboric acid is added at a concentration of, for example, 0.1% by mass or more with respect to the saturated aliphatic hydrocarbon contained in the reactor on the most upstream side of the reactor (reactor 41 in FIG. 3). Add, but not limited to this.

In this preferred embodiment, adding metaboric acid not only to the most upstream reactor (reactor 41 in FIG. 3) but more preferably to one or more other reactors (reactor 42 in FIG. 3). Have. In this way, by adding metaboric acid to each reactor (reactors 41 and 42 in FIG. 3) separately, the amount of splashes caused by metaboric acid is suppressed, the pipe blockage is significantly suppressed, and the production efficiency is improved. Has an effect.

In the present preferred embodiment, metaboric acid is independently added to less than 10% by mass and 7% by mass or less with respect to each saturated aliphatic hydrocarbon contained in one or more other reactors (reactor 42 in FIG. 3). Add at a concentration of 5% by mass or less, or 3% by mass or less. According to such an embodiment, the desired effect of the present invention can be efficiently achieved. In one embodiment of the present invention, metaboric acid is independently added to each saturated aliphatic hydrocarbon contained in one or more other reactors (reactor 42 in FIG. 3), for example, by mass 0.1. It is added at a concentration of% or more, but is not limited to this.

In this preferred embodiment, the internal temperatures of the most upstream reactor (reactor 41 in FIG. 3) and one or more other reactors (reactor 42 in FIG. 3) are independently set above 140 ° C. Set to 200 ° C. or lower, 150 to 190 ° C., or 160 to 180 ° C. If the temperature is 140 ° C. or lower, there is a possibility that the oxygen concentration difference at least at the inlet and outlet of the most upstream reactor cannot be 0.5% by volume or more. Further, the oxidation reaction can be stably carried out by setting the temperature above 140 ° C. and below 200 ° C. Here, "internal temperature" means a value measured by a thermometer installed so as to come into contact with the contents contained in the reactor.

In this preferred embodiment, the temperatures of the reaction gases introduced into the most upstream reactor (reactor 41 in FIG. 3) and one or more other reactors (reactor 42 in FIG. 3) are set independently. Set to more than 140 ° C. and 200 ° C. or lower, 150 to 190 ° C., or 160 to 180 ° C. According to such an embodiment, the difference in oxygen concentration can be efficiently set to 0.5% by volume or more. Further, the oxidation reaction can be stably carried out by setting the temperature above 140 ° C. and below 200 ° C. Here, the temperature of the reaction gas means a value measured by a thermometer installed so as to come into contact with the reaction gas. The air volume of the reaction gas is independently 100 to 1000 liters / hour, preferably 350 to 600 liters / hour, etc. per 1000 g of saturated aliphatic hydrocarbon.

In this preferred embodiment, the circulating gas is introduced into the most upstream reactor (reactor 41 in FIG. 3) and one or more other reactors (reactor 42 in FIG. 3). The preferable temperature range of the circulating gas is the same as the preferable temperature range of the reaction gas.

In this preferred embodiment, the reaction gas is repeatedly introduced and stopped in the most upstream reactor (reactor 41 in FIG. 3) and, if necessary, one or more other reactors (reactor 42 in FIG. 3). Implement intermittent supply. At this time, the intermittent supply is carried out while monitoring. That is, the monitoring is carried out by intermittent supply in which the introduction and the introduction stop of the reaction gas are repeated. Explaining a specific operation method, for example, the reaction gas is applied to the most upstream reactor (reactor 41 in FIG. 3) and one or more other reactors (reactor 42 in FIG. 3) for an arbitrary time. Introduce. After that, the introduction of the reaction gas is stopped for an arbitrary time. The reaction gas is supplied in a plurality of cycles, with the introduction of the reaction gas once and the introduction stop once as one cycle. The number of cycles is not particularly limited, and the monitoring may be performed until the oxygen concentration difference becomes 0.5% by volume or more, but as a guide, for example, about 1 to 10 times, about 2 to 7 times. , Or about 3 to 6 times, but is not limited to this.

In this preferred embodiment, oxygen in the reaction gas introduced into the most upstream reactor (reactor 41 in FIG. 3) and one or more other reactors (reactor 42 in FIG. 3) upon introduction. The concentrations are independently such as 0.5% by volume (vol%) or more and 10% by volume (vol%) or less, preferably 0.5% by volume (vol%) or more and 2.5% by volume (vol%) or less. ).

In this preferred embodiment, the concentration of molecular oxygen in the reaction gas is monotonically increased during the introduction. Further, in one embodiment of the present invention, at the time of the introduction, the slope calculated by the least squares method in the change in the concentration of molecular oxygen in the reaction gas is positive. In this way, the concentration of molecular oxygen in the reaction gas is (monotonically) increased (that is, not decreased or increased) with the passage of time in the intermittent supply, or calculated by the least squares method in the change of concentration. By making the slope positive (that is, the concentration may decrease over time, but the concentration increases on average), it is possible to make the continuous equation with good reactivity. The production volume can be increased.

In this preferred embodiment, the single introduction time in the intermittent supply is set to 0.5-10 minutes, 0.5-5 minutes, or 0.5-3 minutes. By such an embodiment, it is possible to efficiently make a predetermined oxygen concentration difference.

In the present preferred embodiment, one introduction stop time in the intermittent supply is set to 0.5 to 10 minutes and 1 to 10 minutes.

In the present preferred embodiment, the intermittent supply of the reaction gas is switched to the continuous supply after the predetermined oxygen concentration difference is reached. In one embodiment of the present invention, the reaction gas is continuously supplied from at least one inlet 34 of the reactors 41 and 42 in FIG.

In the present preferred embodiment, after switching to the continuous equation, a saturated aliphatic hydrocarbon is further supplied. In one embodiment of the present invention, after switching to the continuous equation, saturated aliphatic hydrocarbons are sequentially supplied. In one embodiment of the present invention, after switching the intermittent supply of the reaction gas to continuous supply, saturated aliphatic hydrocarbons are sequentially supplied from the inlet 33 of the reactor 41.

In this preferred embodiment, the most upstream reactor (reactor 41 in FIG. 3) and one or more other reactors (reactor 42 in FIG. 3) are communicated. In this way, a continuous type (continuous flow type) is started from the batch type to obtain a reaction solution containing an oxide (oxidation reaction product). Here, the saturated aliphatic hydrocarbon supplied after switching to the continuous type may be the same as or different from the saturated aliphatic hydrocarbon added to the reactors (41, 42) above. Good, but preferably the same.

In the present preferred embodiment, the oxidation reaction step may be carried out under atmospheric pressure (normal pressure), pressure or reduced pressure, but is usually carried out under atmospheric pressure (normal pressure) to 30 kg / cm ² G. Further, the liquid phase oxidation reaction may be carried out with stirring (the reactor may be provided with a stirrer).

In this preferred embodiment, one or more of the reactors may be, for example, a stirring tank type or a bubble tower type.

The above step (a-1) produces a borate compound, but there are other unreacted aliphatic hydrocarbons, free alcohols and metaboric acid. Free alcohol has a boiling point close to that of saturated aliphatic hydrocarbons, so it is difficult to separate the two. Therefore, in the esterification step (a-2), this alcohol is orthoboric acid esterified and converted into a borate compound.

That is, in the above step (a-2), the free alcohol contained in the oxide obtained in the above step (a-1) is esterified (orthoboric acid esterification) to obtain a reaction solution containing a borate compound. .. In this step, the free alcohol present in the oxide obtained in step (a-1) is reacted with metaboric acid to convert it into a borate compound. However, since excess metaboric acid is usually present in the oxide, It is not necessary to add new metaboric acid here, but new metaboric acid may be added.

In the above step (a-2), by dehydrating the reaction solution containing the oxide under reduced pressure, the free alcohol contained in the oxidation reaction product can be orthoboric acid esterified and converted into a borate compound. At this time, the orthoboric acid esterification treatment conditions are not particularly limited. For example, the treatment temperature is, but is not limited to, 100 to 220 ° C., preferably 160 to 180 ° C. and the like. In the present specification, the temperature in the esterification step means the value of the temperature measured by the thermometer inserted in the liquid in the reactor. All similar definitions apply herein. The treatment time is, but is not limited to, 5 to 80 minutes, preferably 20 to 60 minutes, and the like. In the present specification, the processing time in the reaction means the residence time in the reactor. Here, the residence time generally means the time during which a substance flowing into a certain finite space stays in the space. Assuming that the volume of the space is V (m ³ ) and the volumetric flow rate of the inflowing substance is θ (m ³ / hr), the residence time (τ) (time) is expressed by the formula: τ (hr) = V / θ. .. The processing pressure is, but is not limited to, 50 to 200 hPa, preferably 90 to 170 hPa and the like. In the present specification, the pressure in the esterification step means the value of the pressure measured by the pressure gauge installed in the upper part of the reactor for measuring the pressure in the gas phase portion. All similar definitions apply herein. The orthoboric acid esterification treatment may be carried out in a nitrogen stream. Under such treatment conditions, the alcohol contained in the oxidation reaction product can be more efficiently esterified with orthoboric acid (a borate compound can be produced in a higher yield).

(Step (b))
In this step, the reaction solution containing the borate compound obtained in the above step (a) is distilled and separated into unreacted saturated aliphatic hydrocarbon (distillate) and distillation residue (column bottom residue). Then, the unreacted saturated aliphatic hydrocarbon is recovered (unreacted saturated aliphatic hydrocarbon recovery step). Since the distillate and the residual liquid at the bottom of the column have a large boiling point difference, they can be easily separated by distillation.

In this step, as a method for distilling the borate compound, known methods such as simple distillation (for example, flash distillation) and molecular distillation can be used, but the method is not particularly limited thereto. At this time, the distillation conditions are not particularly limited. The distillation pressure is, for example, under reduced pressure of 1 to 50 hPa, preferably 3 to 25 hPa, but is not limited thereto. The distillation temperature (particularly the column bottom temperature) is 130 to 250 ° C., preferably 150 to 205 ° C., and is not limited thereto. The distillation time is, but is not limited to, 1 to 205 minutes, preferably 25 to 120 minutes, and the like. Under these conditions, a relatively high boiling point distillation residue (including the desired borate compound), a relatively low boiling point component (unreacted saturated aliphatic hydrocarbon as a main component, and some carbonyl). Compounds, organic acid esters, organic acids, olephines, etc.) can be separated more efficiently.

The unreacted saturated aliphatic hydrocarbon recovered in this step may be reused (circulated) in the oxidation reaction step (a-1). In this case, for example, even if the saturated aliphatic hydrocarbon of the distillate is removed and then reused as it is in the oxidation reaction step (a-1); it is contained in the saturated aliphatic hydrocarbon recovered in this step. After hydrogenating the carbonyl compound and olephins, they may be reused in the oxidation reaction step (a-1), but the above is not limited.

In addition to or in place of the above, the unreacted saturated aliphatic hydrocarbon recovered in this step may be reused (circulated) in the step (i) of the first aspect. The saturated aliphatic hydrocarbon recovered in the above recovery step usually contains 2% by mass or more (for example, about 2 to 5% by mass) of an alcohol component. Therefore, in the case of this embodiment, the content of the alcohol component of the saturated aliphatic hydrocarbon in the step (i) is less than 2% by mass (preferably 1.5% by mass or less, more preferably less than 1% by mass). The unreacted saturated aliphatic hydrocarbon recovered in this recovery step is mixed with the unused saturated aliphatic hydrocarbon separated in the step (ii) of the first aspect, and then the above step ( It can be reused for i).

(Step (c))
In this step, the distillation residue separated in the above step (b) is hydrolyzed and separated into an aqueous layer containing orthoboric acid and an organic layer (hydrolysis step).

Specifically, hot water is added to the distillation residue to hydrolyze it, and the distillation residue is separated into an aqueous layer containing orthoboric acid and an organic layer. Here, the temperature (liquid temperature) of hot water is, but is not limited to, 70 to 150 ° C., preferably 90 to 100 ° C. and the like. The amount of hot water added is, but is not limited to, 1 to 20 times by mass, preferably 2 to 10 times by mass, or the like with respect to the distillation residue. The hydrolysis time is, but is not limited to, 5 to 60 minutes, preferably 20 to 30 minutes, and the like. Under such conditions, the distillation residue can be sufficiently hydrolyzed to more efficiently separate the aqueous layer containing orthoboric acid from the organic layer.

The aqueous layer containing orthoboric acid separated in this step may be reused in the dehydration step (i) in the method according to the first aspect. That is, in one embodiment of the present invention, the method of the present disclosure uses the method according to the first aspect to produce metaboric acid from the orthoboric acid separated in c) and circulate it in a). Further have. In this case, the aqueous layer is crystallized and then separated (for example, centrifuged) to separate orthoboric acid from the aqueous layer, and the orthoboric acid is dehydrated in the method according to the first aspect (i). ) Can be reused (circulated). When the orthoboric acid separated here is reused in the dehydration step (i) in the method according to the first aspect, the organic substances in the orthoboric acid (fatty acid, fatty acid ester, fatty acid sodium, organic acid such as fatty acid potassium, organic acid, organic) The content of (acetate, organic acid ester, etc.) is less than 1% by mass, more preferably 0.6% by mass or less (lower limit: 0% by mass or detection limit or less). As a result, corrosion of the reactor (dehydrating group) during the dehydration reaction can be suppressed more effectively. In the present specification, the content of organic matter in orthoboric acid adopts a value measured using a total organic carbon meter (TOC). The above method is an example, and the present invention is not limited to the above method.

(Step (d))
In this step, the organic layer separated in the above step (c) is saponified with an alkali to separate it into an alkaline aqueous solution layer and a crude alcohol layer (saponification step). As a result, the organic acid and the acid in the organic acid ester can be separated and removed.

Here, as the alkali, for example, sodium hydroxide, potassium hydroxide, sodium hydrogencarbonate, potassium hydrogencarbonate and the like can be used, but the alkali is not limited thereto. Further, if necessary after the saponification treatment with the above alkali, it may be washed with water. The saponification condition is not particularly limited, and the same conditions as before can be applied in the same manner. For example, the saponification temperature is 120 to 160 ° C, preferably 135 to 145 ° C and the like, but is not limited thereto. The saponification time is, but is not limited to, 30 to 120 minutes, preferably 50 to 90 minutes, and the like. Under such conditions, the saponification process can proceed more efficiently.

(Step (e))
In this step, the crude alcohol layer separated in the above step (d) is purified. As a result, the desired secondary alcohol is obtained (refining step).

Here, the purification method is not particularly limited, and a known method can be applied in the same manner or appropriately modified. For example, it can be purified by distilling or fractionating the crude alcohol layer. The purification pressure at this time is, but is not limited to, 1 to 45 hPa, preferably 4 to 12 hPa and the like. Under such conditions, it can be appropriately separated according to the boiling point range (for example, a fraction having a boiling point range of 95 to 120 ° C. and a fraction having a boiling point range of 120 to 150 ° C.). In the above case, the fraction having a boiling point range of 95 to 120 ° C. usually contains a small amount of saturated aliphatic hydrocarbon, carbonyl compound and monohydric primary alcohol (monoalcohol). Further, the fraction having a boiling point range of 120 to 150 ° C. contains a trace amount of a carbonyl compound and a secondary alcohol (monoalcohol), and in this case, most of the secondary alcohol is a desired monohydric secondary alcohol. be.

Between the above step (d) and this step (e), at least one selected from a heavy separation step, an alkali treatment step (particularly potassium hydroxide treatment step), and a light separation step according to a conventionally known method. The process may be performed.

The effect of the present invention will be described with reference to the following examples. However, the technical scope of the present invention is not construed as being limited to the following examples, and examples obtained by appropriately combining the technical means disclosed in each example are also included in the scope of the present invention. In the following examples, the operation was performed at room temperature (25 ° C.) unless otherwise specified. Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass", respectively.

Example 1: Production of metaboric acid A mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms (average molecular weight: 184, NP in FIG. 1) is placed in a reactor 1 with a stirrer 2 having a capacity of 5 L shown in FIG. 1700 g and 1000 g of orthoboric acid were charged to prepare an orthoboric acid mixture M. The mixture of saturated aliphatic hydrocarbons as a raw material contains saturated aliphatic hydrocarbons having 12 to 14 carbon atoms (n-dodecane, n-tridecane and n-tetradecane) and saturated aliphatic hydrocarbons having 12 to 14 carbon atoms. It is contained in a proportion of more than 95% by mass based on the total mass of the mixture of. Moreover, when the content of the alcohol component in the mixture of saturated aliphatic hydrocarbons was measured by gas chromatography, it was below the detection limit (substantially no alcohol component was contained). As the reactor 1, the entire reactor is made of stainless steel (SUS316), and the upper part 3 of the reactor (shaded portion in FIG. 1; height of Hastelloy-coated portion / total height of reactor = 45%) has Hastelloy C-22 ( Composition: Ni 57.0% by mass, Cr 20.5% by mass, Mo 14.2% by mass, Fe 2.3% by mass, W: 3.2% by mass, V 0.25% by mass, C 0.01% by mass %) Was lined to a thickness of 0.5 mm (the top of the reactor from the top of the dehydrator to 45% of the total height of the dehydrator is covered with Hastelloy).

The obtained orthoboric acid mixture M is heated to 160 ° C. by steam while stirring with a stirrer 2 at a speed of 45 rpm, and the orthoboric acid is intramolecularly dehydrated in the presence of a mixture of saturated aliphatic hydrocarbons for 5 hours. It was converted to β-type metaboric acid. As a result, 2330 g of a mixture containing 630 g of β-type metaboric acid and 1700 g of saturated aliphatic hydrocarbon was obtained (yield of β-type metaboric acid: 1 mol with respect to 1 mol of orthoboric acid) (step (i)). It was confirmed by X-ray crystallography that it was β-type metaboric acid. Further, steam and vapors of saturated aliphatic hydrocarbons (“water + NP” in FIG. 1) are generated during the dehydration reaction, and these vapors are extracted from the upper part of the reactor through the pipe 4 to the condenser. Introduced into 5 to condense steam, water condensed in a condenser and saturated aliphatic hydrocarbons were introduced into a separation tank (Settler) 6 to separate water from saturated aliphatic hydrocarbons (NPs) ( In step (ii)), water was withdrawn from the system, and the saturated aliphatic hydrocarbon (NP) was returned to the reactor 1 through the pipe 7 to carry out the above dehydration reaction. The content of the alcohol component in the saturated aliphatic hydrocarbon (NP) after separation in the separation tank (Settler) 6 was measured by gas chromatography and found to be below the detection limit (substantially the alcohol component). Did not include).

After the above reaction was completed, the inner wall of the reactor and the inside of the pipe were visually observed. As a result, almost no deposits were found on the inner wall of the reactor or inside the piping. No corrosion was observed on the inner wall of the reactor (particularly the inner wall of the upper part of the reactor).

Example 2: Preparation of secondary alcohol The reaction was carried out in the same manner as in Example 1 above to obtain a mixture containing β-type metaboric acid and a saturated aliphatic hydrocarbon.

A mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms (average molecular weight: 184, saturated aliphatic hydrocarbons having 12 to 14 carbon atoms and saturated aliphatic hydrocarbons having 12 to 14 carbon atoms) was added to 92.5 g of the obtained mixture. 932.5 g (contained in a proportion of more than 95% by mass based on the total mass of the mixture) was added, and 1025 g of a mixture containing β-type metaboic acid and saturated aliphatic hydrocarbon (composition: 25 g of β-type metaboric acid and saturated aliphatic hydrocarbon). 1000 g of hydrogen) was obtained. The saturated aliphatic hydrocarbon has an average molecular weight of 184 as a mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms, and a saturated aliphatic hydrocarbon having 12 to 14 carbon atoms having 12 to 14 carbon atoms. It is contained in a proportion of more than 95% by mass based on the total mass of the mixture of saturated aliphatic hydrocarbons. This mixture was placed in a cylindrical reactor having a capacity of 3 L, and a mixed gas having an oxygen concentration of 3.5 vol% and a nitrogen concentration of 96.5 vol% was blown at a rate of 430 L per hour, and liquid phase oxidation was performed at 170 ° C. under normal pressure for 2 hours. The reaction was carried out to obtain a reaction solution containing an oxide (oxidation reaction mixture) (oxidation reaction step).

After the oxidation reaction, the reaction solution containing the oxide was depressurized to esterify the free alcohol with the excessively added boric acid to obtain a borate compound. This esterification was carried out at 105 hPa, 165 ° C., for 60 minutes (esterification step). Next, the unreacted saturated aliphatic hydrocarbon was recovered by performing flash distillation of this borate compound (borate ester mixture) at 200 ° C. and 7 hPa for 60 minutes (unreacted saturated aliphatic hydrocarbon recovery step). Then, the residual liquid was hydrolyzed with a large amount (2% by mass with respect to the residual liquid) of hot water at 95 ° C. for 20 minutes, and separated into an aqueous layer containing orthoboric acid and an organic layer (hydrolysis step). The obtained organic layer was saponified and washed with water at 140 ° C. for 70 minutes using sodium hydroxide to remove organic acids and organic acid esters (saponification step). This organic layer was fractionated at 7 hPa to obtain a boiling point range of 95 to 120 ° C. as the first fraction and a boiling point range of 120 to 150 ° C. as the second fraction (purification step). Here, the first fraction (fraction having a boiling point range of 95 ° C. or higher and lower than 120 ° C.) was a mixture of a small amount of saturated aliphatic hydrocarbon, carbonyl compound and monohydric primary alcohol (monoalcohol). The secondary fraction (fraction with a boiling point range of 120 to 150 ° C.) is a mixture of a trace amount of a carbonyl compound and a secondary alcohol (monoalcohol), in which the majority of the secondary alcohol is monohydric secondary. It was a secondary alcohol.

Example 3: Production of Secondary Alcohol An operation was carried out in the same manner as in Example 2 above, and the alcohol was separated into an aqueous layer containing orthoboric acid and an organic layer (hydrolysis step). Next, the aqueous layer obtained above was crystallized and centrifuged to separate orthoboric acid. When the content of the alcohol component in the orthoboric acid obtained above was measured by gas chromatography, it was below the detection limit (substantially did not contain the alcohol component). Further, the amount of organic substances (organic acids, etc.) in the orthoboric acid obtained above was measured using a total organic carbon meter (TOC) and found to be 0.6% by mass.

In Example 1, the same procedure as in Example 1 was carried out except that the orthoboric acid obtained above was used instead, to obtain a mixture containing β-type metaboric acid and a saturated aliphatic hydrocarbon. Here, when the content of the alcohol component in the saturated aliphatic hydrocarbon (NP) after separation in the separation tank (Settler) 6 was measured by gas chromatography, it was below the detection limit (substantially the alcohol component). Was not included in). After the dehydration reaction was completed, the inner wall of the reactor and the inside of the pipe were visually observed. As a result, almost no deposits were found on the inner wall of the reactor or inside the piping. In addition, almost no corrosion was observed on the inner wall of the reactor (particularly the inner wall of the upper part of the reactor). From the above results, the orthoboric acid (recovered orthoboric acid) recovered in the secondary alcohol production process contains organic substances such as organic acids that may cause corrosion of the dehydrator, but the gas phase part is made of hasterois having excellent corrosion resistance. It is considered that such recovered orthoboric acid can be used in the production of metaboric acid by using a lined reactor.

From the above results, it was confirmed that according to the method of the present invention, no deposits were formed on the inner wall of the reactor or the inside of the pipe even if the reaction was continuously carried out until the acid was substantially completely converted to metaboric acid. .. Further, from the above results, it is considered that according to the method of the present invention, the dehydration reaction can be stably carried out without increasing the stirring power while smoothly circulating the saturated aliphatic hydrocarbon (NP). Will be done.

Next, in the above-mentioned Example 2, the same operation as in Example 2 was carried out except that the mixture containing the β-type metaboric acid and the saturated aliphatic hydrocarbon obtained above was used instead, and the secondary alcohol was prepared. Manufactured.

Comparative Example 1
1000 g of a mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms (average molecular weight: 184) and 25 g of metaboric acid were placed in a cylindrical reactor having a capacity of 3 L and having an oxygen concentration of 3.5 vol% and a nitrogen concentration of 96.5 vol%. A mixed gas was blown at a rate of 430 L per hour, and an oxidation reaction was carried out at 170 ° C. under normal pressure for 2 hours to obtain an oxidation reaction mixture (oxidation reaction step). The mixture of saturated aliphatic hydrocarbons as a raw material contains 95% by mass of saturated aliphatic hydrocarbons (n-dodecane, n-tridecane and n-tetradecane) having 12 to 14 carbon atoms with respect to the total mass of the mixture. Including at a rate exceeding.

This oxidation reaction mixture was treated at 105 hPa at 165 ° C. for 60 minutes, and the alcohol contained therein was orthoboric acid esterified to obtain a borate compound (boric acid ester mixture) (esterification step). Next, this borate compound (borate ester mixture) was flash-distilled at 200 ° C. (tower bottom temperature) at 7 hPa for 60 minutes to recover unreacted saturated aliphatic hydrocarbons (unreacted saturated aliphatic hydrocarbon recovery step). ). The content of the alcohol component in the unreacted saturated aliphatic hydrocarbon (recovered NP) recovered here was measured by gas chromatography and found to be 3.5% by mass. Moreover, when the hydroxyl value of this recovered NP was measured according to the method described in JIS K1557-1 (2007), it was 9.0 mgKOH / g.

A reactor 1 with a stirrer 2 having a capacity of 5 L shown in FIG. 1 was charged with 1700 g of the recovered NP (“NP” in FIG. 1) and 1000 g of orthoboric acid obtained above to prepare an orthoboric acid mixture M. As the reactor 1, a reactor entirely made of stainless steel (SUS316) was used.

The obtained orthoboric acid mixture M is heated to 160 ° C. by steam while stirring with a stirrer 2 at a speed of 45 rpm, and the orthoboric acid is intramolecularly dehydrated in the presence of a mixture of saturated aliphatic hydrocarbons for 5 hours. It was converted to β-type metaboric acid. As a result, a mixture containing β-type metaboric acid and a saturated aliphatic hydrocarbon was obtained. Steam and saturated aliphatic hydrocarbon vapors (“water + NP” in FIG. 1) are generated during the dehydration reaction, and these vapors are extracted from the upper part of the reactor through the pipe 4 to the condenser. Introduced into 5 to condense steam, water condensed in a condenser and saturated aliphatic hydrocarbons were introduced into a separation tank (Settler) 6 to separate water from saturated aliphatic hydrocarbons (NPs). Water was taken out of the system, and the saturated aliphatic hydrocarbon (NP) was returned to the reactor 1 through the pipe 7 to carry out the above dehydration reaction.

After the above reaction was completed, the inner wall of the reactor and the inside of the pipe were visually observed. As a result, it was confirmed that a considerable amount of deposits were accumulated on the inner wall of the reactor and the inside of the piping. In addition, corrosion was observed on the inner wall of the upper part of the reactor.

In Comparative Example 1 using the saturated aliphatic hydrocarbon (recovered NP) recovered after the oxidation reaction, deposits were formed on the inner wall of the reactor and the inside of the pipe. Such deposits can lead to increased agitation power and blockage of piping. Therefore, it is necessary to stop the reaction in order to remove the deposits, which is not preferable from the viewpoint of mass production. Further, since the recovered saturated aliphatic hydrocarbon (recovered NP) contains a considerable amount of alcohol component, the formation of the deposit is due to the reaction of this alcohol component with orthoboric acid to form a borate compound. It is presumed that there is.

Example 4: Production of Metaboric Acid An unreacted saturated aliphatic hydrocarbon (recovered NP) having an alcohol component content of 3.5% by mass in the recovered NP is produced in the same manner as in Comparative Example 1 above. Recovered (unreacted saturated aliphatic hydrocarbon recovery step).

The recovered NP obtained above is prepared so that the content of the saturated aliphatic hydrocarbon mixture (average molecular weight: 184) (new NP) having 12 to 14 carbon atoms and the alcohol component is 1.5% by mass. , The mixing ratio of the recovered NP and the new NP (recovered NP: mixed mass ratio of the new NP) was 3: 4, and a saturated aliphatic hydrocarbon mixture (NP1) was obtained. The hydroxyl value of this NP1 was 4.0 mgKOH / g.

In Example 1, the same operation was performed except that NP1 (alcohol component content = 1.5% by mass) obtained above was used instead of NP. Further, the content of the alcohol component in the saturated aliphatic hydrocarbon after separation in the separation tank (Settler) 6 was measured by gas chromatography and found to be 1.5% by mass.

After the above reaction was completed, the inner wall of the reactor and the inside of the pipe were visually observed. As a result, almost no deposits were found on the inner wall of the reactor or inside the piping. The amount of deposits visually observed was smaller in Example 1. In addition, almost no corrosion was observed on the inner wall of the reactor (particularly the inner wall of the upper part of the reactor).

From the comparison with the results of Example 1 above, it is considered that the content of the alcohol component in the saturated aliphatic hydrocarbon used for producing metaboric acid is one of the major causes of the formation of deposits. Further, by controlling the content of the alcohol component in the saturated aliphatic hydrocarbon to less than 2% by mass (particularly 1.5% by mass or less), the formation of deposits on the inner wall of the reactor and the inside of the pipe is effectively suppressed. It is considered possible.

Comparative Example 2: Production of Metaboric Acid An unreacted saturated aliphatic hydrocarbon (recovered NP) having an alcohol component content of 3.5% by mass in the recovered NP was produced in the same manner as in Comparative Example 1 above. Recovered (unreacted saturated aliphatic hydrocarbon recovery step).

The recovered NP obtained above is prepared so that the content of the saturated aliphatic hydrocarbon mixture (average molecular weight: 184) (new NP) having 12 to 14 carbon atoms and the alcohol component is 2.5% by mass. , The mixing ratio of the recovered NP and the new NP (recovered NP: mixed mass ratio of the new NP) was 5: 2, and a saturated aliphatic hydrocarbon mixture (NP2) was obtained. The hydroxyl value of this NP2 was 6.8 mgKOH / g.

1700 g of the above-mentioned NP2 (“NP” in FIG. 1) and 1000 g of orthoboric acid (recovered orthoboric acid) were charged into the reactor 1 with a stirrer 2 having a capacity of 5 L shown in FIG. Was prepared. As the reactor 1, a reactor entirely made of stainless steel (SUS316) was used.

The obtained orthoboric acid mixture M is heated to 160 ° C. by steam while stirring with a stirrer 2 at a speed of 45 rpm, and the orthoboric acid is intramolecularly dehydrated in the presence of a mixture of saturated aliphatic hydrocarbons for 5 hours. It was converted to β-type metaboric acid. As a result, a mixture containing β-type metaboric acid and a saturated aliphatic hydrocarbon was obtained. Steam and saturated aliphatic hydrocarbon vapors (“water + NP” in FIG. 1) are generated during the dehydration reaction, and these vapors are extracted from the upper part of the reactor through the pipe 4 to the condenser. Introduced into 5 to condense steam, water condensed in a condenser and saturated aliphatic hydrocarbons were introduced into a separation tank (Settler) 6 to separate water from saturated aliphatic hydrocarbons (NPs). Water was taken out of the system, and the saturated aliphatic hydrocarbon (NP) was returned to the reactor 1 through the pipe 7 to carry out the above dehydration reaction.

After the above reaction was completed, the inner wall of the reactor and the inside of the pipe were visually observed. As a result, it was confirmed that deposits were accumulated on the inner wall of the reactor and the inside of the piping. The amount of deposits visually observed was larger in Comparative Example 1. In addition, corrosion was observed on the inner wall of the upper part of the reactor.

From the comparison with the result of Comparative Example 1 above, the saturated aliphatic hydrocarbon (recovered NP) recovered after the oxidation reaction can be used in combination with fresh saturated aliphatic carbon hydrogen in the saturated aliphatic carbon. It can be seen that when the alcohol content is 2% by mass or more, deposits are formed on the inner wall of the reactor and the inside of the pipe. Such deposits can lead to increased agitation power and blockage of piping. Therefore, it is necessary to stop the reaction in order to remove the deposits, which is not preferable from the viewpoint of mass production.

Example 5: Preparation of secondary alcohol The reaction was carried out in the same manner as in Example 1 above to obtain a mixture containing β-type metaboric acid and a saturated aliphatic hydrocarbon.

A mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms (average molecular weight: 184, a mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms and a mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms) in 74 g of the obtained mixture. 1946 g (containing in a proportion of more than 95% by mass based on the total mass of the compound) was added to add 2020 g of a mixture containing β-type metaboic acid and saturated aliphatic hydrocarbon (composition: 20 g of β-type metaboric acid and 2000 g of saturated aliphatic hydrocarbon). Obtained. The saturated aliphatic hydrocarbon has an average molecular weight of 184 as a mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms, and a saturated aliphatic hydrocarbon having 12 to 14 carbon atoms having 12 to 14 carbon atoms. It is contained in a proportion of more than 95% by mass based on the total mass of the mixture of saturated aliphatic hydrocarbons.

As shown in FIG. 3, each reactor (41, 42) of the two reactors 1 connected in series was charged with 1010 g, 1010 g of the mixture containing the β-type metaboric acid and the saturated aliphatic hydrocarbon obtained above. I stuck in each. The above mixture contains metaboric acid in an amount of 1% by mass and 1% by mass, respectively, with respect to saturated aliphatic hydrocarbons.

The internal temperatures of each reactor (41, 42) were all raised to 170 ° C. Then, a circulating gas (nitrogen gas: 170 ° C.) was introduced into each reactor (41, 42) via the inlet 34.

Next, intermittent supply was performed to each reactor (41, 42) by repeatedly introducing and stopping the introduction of the reaction gas.

More specifically, the temperature of the reaction gas introduced into each reactor (41, 42) was adjusted to 170 ° C. Further, the oxygen concentration of the reaction gas introduced into each reactor (41, 42) at this time was adjusted to be 0.5 to 10% by volume and 0.5 to 10% by volume, respectively. At this time, the time for introducing the reaction gas into each reactor (41, 42) at one time was set to 1 to 3 minutes. The time for stopping the introduction of the reaction gas once was also set to 1 to 3 minutes. The introduction was carried out so that the slope calculated by the least squares method in the change in the concentration of molecular oxygen in the reaction gas became positive.

Then, the intermittent supply was carried out while monitoring the difference in oxygen concentration at the inlet 34 and the outlet 35 of each reactor (41, 42). It was confirmed that the predetermined oxygen concentration difference was 1.0% by volume (that is, 0.5% by volume or more) 1 hour after the reaction gas was first introduced into each reactor (41, 42).

After the above confirmation, the intermittent supply of the reaction gas is switched to the continuous supply, the NP is sequentially supplied at 50 mL / min from the inlet 33 of the reactor 41, and each reactor (41, 42) is communicated to be continuous. The oxidation reaction step was carried out by (continuous flow type) to obtain an oxide (oxidation reaction mixture).

After the oxidation reaction, the reaction solution containing the oxide was depressurized to esterify the free alcohol with the excessively added boric acid to obtain a borate compound. This esterification was carried out at 105 hPa, 165 ° C., for 60 minutes (esterification step). Next, the unreacted saturated aliphatic hydrocarbon was recovered by performing flash distillation of this borate compound (borate ester mixture) at 200 ° C. and 7 hPa for 60 minutes (unreacted saturated aliphatic hydrocarbon recovery step). Then, the residual liquid was hydrolyzed with a large amount (2% by mass with respect to the residual liquid) of hot water at 95 ° C. for 20 minutes, and separated into an aqueous layer containing orthoboric acid and an organic layer (hydrolysis step). The obtained organic layer was saponified and washed with water at 140 ° C. for 70 minutes using sodium hydroxide to remove organic acids and organic acid esters (saponification step). This organic layer was fractionated at 7 hPa to obtain a fraction having a boiling point range of 95 ° C. or higher and lower than 120 ° C. as the first fraction and a fraction having a boiling point range of 120 to 150 ° C. as the second fraction (purification step). Here, the first fraction (fraction having a boiling point range of 95 ° C. or higher and lower than 120 ° C.) was a mixture of a small amount of saturated aliphatic hydrocarbon, carbonyl compound and monohydric primary alcohol (monoalcohol). The secondary fraction (fraction with a boiling point range of 120 to 150 ° C.) is a mixture of a trace amount of a carbonyl compound and a secondary alcohol (monoalcohol), in which the majority of the secondary alcohol is monohydric secondary. It was a secondary alcohol.

Since the amount of secondary alcohol produced per day was 4 kg by starting up in a continuous system (continuous distribution system) by this method, it was judged that the reactivity of the oxidation step was good.

In this embodiment, the experiment was conducted in "series", but it has been confirmed that the same result can be obtained by making it "parallel".

1 ... Reactor,
2 ... Stirrer,
3 ... Upper part of the reactor,
4, 7 ... plumbing,
5 ... Condenser,
6 ... Separation tank (setler),
M ... mixture,
30 ... (plural) reactors,
41 ... (one) reactor,
42 ... (one) reactor,
32 ... plumbing,
33 ... Inlet for saturated aliphatic hydrocarbons and metaboric acid,
34 ... Inlet for reaction gas and circulating gas,
35 ... Outlet where reaction gas and circulating gas come out.

Claims (8)

i) Orthoboric acid is dehydrated in a dehydrator in the presence of a linear saturated aliphatic hydrocarbon having 10 to 30 carbon atoms to obtain a mixture containing metaboric acid, saturated aliphatic hydrocarbon and water.
ii) After distilling off the saturated aliphatic hydrocarbon and water from the mixture, the saturated aliphatic hydrocarbon and water are separated.
iii) The saturated aliphatic hydrocarbon separated in ii) is returned to i).
Have that
The method for producing metaboric acid, wherein the content of the alcohol component in the saturated aliphatic hydrocarbon is less than 2% by mass in the above i). The method according to claim 1, wherein at least the gas phase portion of the dehydrator is formed of Hastelloy. The method according to claim 2 , wherein the gas phase portion is a portion in a range from the top of the dehydrator to 60% with respect to the total height of the reactor. In the above i), the mixing ratio of the saturated aliphatic hydrocarbon and the orthoboric acid (saturated aliphatic hydrocarbon: mixed mass ratio of orthoboric acid) is 0.5 to 5: 1, claims 1 to 3. The method according to any one of the above. a) In the presence of metaboric acid, a saturated aliphatic hydrocarbon having a linear structure having 10 to 30 carbon atoms is liquid-phase oxidized and esterified with a molecular oxygen-containing gas to obtain a reaction solution containing a borate compound.
b) The reaction solution containing the borate compound is distilled to separate it into unreacted saturated aliphatic hydrocarbons and distillation residues.
c) The distillation residue is hydrolyzed to separate it into an aqueous layer containing orthoboric acid and an organic layer.
d) The organic layer is saponified with an alkali to separate it into an aqueous alkaline layer and a crude alcohol layer.
e) A method for producing a secondary alcohol, which comprises purifying the crude alcohol layer to obtain a secondary alcohol.
The method in which the metaboric acid is produced by the method according to any one of claims 1 to 4 in the step a). 5. The method according to claim 5 , further comprising producing metaboric acid from the orthoboric acid separated in c) using the method according to any one of claims 1 to 4 and circulating it in a). the method of. a-1) Metaboric acid, a linear saturated aliphatic hydrocarbon having 10 to 30 carbon atoms and a molecular oxygen-containing gas are supplied to the reactor, and the saturated aliphatic hydrocarbon is molecular in the presence of metaboric acid. Liquid phase oxidation with a state oxygen-containing gas to obtain a reaction solution containing an oxide.
a-2) The oxide is esterified to obtain a reaction solution containing a borate compound.
b) The reaction solution containing the borate compound is distilled to separate it into unreacted saturated aliphatic hydrocarbons and distillation residues.
c) The distillation residue is hydrolyzed to separate it into an aqueous layer containing orthoboric acid and an organic layer.
d) The organic layer is saponified with an alkali to separate it into an aqueous alkaline layer and a crude alcohol layer.
e) A method for producing a secondary alcohol, which comprises purifying the crude alcohol layer to obtain a secondary alcohol.
In the step a-1), the metaboric acid is produced by the method according to any one of claims 1 to 4.
The reactor consists of two or more reactors that can be switched between batch and continuous.
Each reactor of the two or more reactors has a saturated aliphatic hydrocarbon added.
It has the addition of metaboric acid to the most upstream reactor of the two or more reactors.
Starting to obtain the oxide in a batch system with the most upstream reactor, monitoring the oxygen concentration difference at the inlet and outlet of the most upstream reactor, the oxygen concentration difference is 0.5 volumes. A method for producing a secondary alcohol, which comprises switching to a continuous system when the concentration becomes% or more. A reactor for producing metaboric acid used in the process of producing secondary alcohols , wherein the reactor has a gas phase in the range from the top of the reactor to 60% of the total height of the reactor. A reactor having a portion and said gas phase portion formed of Hastelloy.

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