Patent Description:
The present application relates to a method for producing neopentyl glycol.

Neopentyl glycol (NPG) is a white crystalline substance with a melting point of <NUM> or higher, is used as an important intermediate for various synthetic resins, and is being widely used in industries as a raw material for various plastic powder paints, synthetic lubricants, plasticizers, surfactants, textile processing agents, etc..

Such NPG is generally produced by performing aldol condensation reaction of isobutyl aldehyde and formaldehyde to make hydroxypivaldehyde (HPA), and then reacting this HPA with hydrogen under a catalyst.

Conventionally, HPA has been subjected to hydrogenation reaction using a slurry-type Ni-based catalyst. In this case, crude NPG, which is a hydrogenation reaction product, contains <NUM>,<NUM>,<NUM>-trimethyl-<NUM>,<NUM>-pentanediol (TMPD), hydroxypivalic acid NPG ester (HPNE), etc. Since TMPD and HPNE have a boiling point very similar to that of NPG, they cannot be separated by simple distillation. Since HPNE is unstable when distilling the reaction mixture and leads to a decrease in the yield of NPG, it is commercially converted to NPG by saponification reaction by adding sodium hydroxide. However, since sodium salts of HPA or other organic acids produced by the saponification reaction promote the decomposition reaction of NPG at a high temperature of <NUM> or higher, the distillation process is constrained. Further, it is impossible to remove TMPD which is not converted to a non-volatile sodium salt when performing the saponification reaction. <CIT> discloses a method for producing neopentyl glycol which comprises hydrogenating HPA in the presence of hydrogen and a hydrogenation catalyst containing nickel or nickel-chromium, in a liquid phase comprising less than <NUM>% water.

Therefore, efforts for producing NPG at a high yield and in an economical way are continuously being made in the art.

The present application aims to provide a method for producing neopentyl glycol.

The present application provides a method for producing neopentyl glycol, comprising a step of injecting a hydroxypivaldehyde (HPA) solution and hydrogen into a hydrogenation reactor to perform a hydrogenation reaction, and comprising a step of adjusting the content of H<NUM>O contained in the hydroxypivaldehyde solution to <NUM>% by weight or less before the hydroxypivaldehyde solution is injected into the hydrogenation reactor, wherein the hydrogenation reactor is a reactor comprising a catalyst in which copper is supported on a silicon oxide support as a fixed bed.

A method for producing neopentyl glycol according to an embodiment of the present application can slow the aging of the catalyst in the hydrogenation reaction by adjusting the content of H<NUM>O contained in the hydroxypivaldehyde solution injected into the hydrogenation reactor to <NUM>% by weight or less.

Accordingly, the method for producing neopentyl glycol according to an embodiment of the present application can increase the period of use of the catalyst in the hydrogenation reaction and reduce the process cost due to catalyst purchase and catalyst replacement.

In the present specification, when a member is said to be located "on" other member, this comprises not only a case in which a member is in contact with other member but also a case in which another member exists between the two members.

In the present specification, when a part "comprises" a certain component, this means that other components may be further comprised rather than excluding other components unless there is a specific opposite description.

As described above, efforts for producing NPG at a high yield and in an economical way are continuously being made in the art.

In particular, during a process for producing neopentyl glycol, H<NUM>O is contained at a high content of about <NUM> to <NUM>% by weight in a hydroxypivaldehyde (HPA) solution, which is a raw material injected into the reactor. In the process for producing neopentyl glycol, a fixed-bed reactor (FBR) comprising a Cu/SiO<NUM> catalyst as a fixed bed is used. The present applicant has found out that during the process for producing neopentyl glycol, the FBR operation period can be determined by long-term stability of the Cu/SiO<NUM> catalyst, and H<NUM>O contained in the hydroxypivaldehyde (HPA) solution may affect the long-term stability of the Cu/SiO<NUM> catalyst.

Accordingly, during the process of producing neopentyl glycol in the present application, long-term stability of the Cu/SiO<NUM> catalyst in the FBR has been intended to be secured by adjusting the content of H<NUM>O contained in the hydroxypivaldehyde (HPA) solution injected into the reactor.

A method for producing neopentyl glycol according to the present application comprises a step of performing a hydrogenation reaction by injecting a hydroxypivaldehyde (HPA) solution and hydrogen into a hydrogenation reactor, and comprises a step of adjusting the content of H<NUM>O contained in the hydroxypivaldehyde solution to <NUM>% by weight or less before the hydroxypivaldehyde solution is injected into the hydrogenation reactor, wherein the hydrogenation reactor is a reactor comprising a catalyst in which copper is supported on a silicon oxide support as a fixed bed.

In an embodiment of the present application, based on the total weight of the hydroxypivaldehyde solution injected into the hydrogenation reactor, the content of H<NUM>O contained in the hydroxypivaldehyde solution injected into the hydrogenation reactor may be <NUM>% by weight or less, <NUM>% by weight or less, <NUM>% by weight or less, or <NUM>. When the content range of H<NUM>O contained in the hydroxypivaldehyde solution injected into the hydrogenation reactor is satisfied, the aging of the Cu/ SiO<NUM> catalyst in the hydrogenation reaction can be slowed, and accordingly the period of use of the catalyst in the hydrogenation reaction can be increased, and the process cost due to catalyst purchase and catalyst replacement can be reduced. Further, when the content of H<NUM>O contained in the hydroxypivaldehyde solution injected into the hydrogenation reactor exceeds <NUM>% by weight, it is not preferable since long-term stability of the Cu/SiO<NUM> catalyst in a fixed-bed reactor (FBR) cannot be secured. In particular, considering the content of Si eluted, it is more preferable to adjust the content of H<NUM>O contained in the hydroxypivaldehyde solution injected into the hydrogenation reactor to <NUM>% by weight or less.

In an embodiment of the present application, the content of H<NUM>O in the hydroxypivaldehyde solution may be controlled to <NUM>% by weight or less using a distillation column.

The distillation column may be a single distillation column or a multi-stage distillation column. For example, the distillation column may be a tray type multi-stage distillation column, but is not limited thereto, and content known in the art may be used. Further, conditions such as temperature, pressure, etc. of the distillation column can be appropriately set by those skilled in the art so as to control the content of H<NUM>O in the hydroxypivaldehyde solution to <NUM>% by weight or less as in the embodiment of the present application.

In an embodiment of the present application, the hydroxypivaldehyde solution before the step of adjusting the content of H<NUM>O contained in the hydroxypivaldehyde solution to <NUM>% by weight or less may contain <NUM> to <NUM>% by weight of hydroxypivaldehyde, <NUM> to <NUM>% by weight of neopentyl glycol, <NUM> to <NUM>% by weight of alcohol, <NUM> to <NUM>% by weight of H<NUM>O, and <NUM> to <NUM>% by weight of a high-boiling point material. Further, the hydroxypivaldehyde solution before the step of adjusting the content of H<NUM>O contained in the hydroxypivaldehyde solution to <NUM>% by weight or less may contain <NUM> to <NUM>% by weight of hydroxypivaldehyde, <NUM> to <NUM>% by weight of neopentyl glycol, <NUM> to <NUM>% by weight of alcohol, <NUM> to <NUM>% by weight of H<NUM>O, and <NUM> to <NUM>% by weight of a high-boiling point material. The hydroxypivaldehyde solution as described above has an effect of suppressing the formation of byproducts since the heat of reaction can be minimized without deteriorating the reactivity.

The alcohol may be <NUM>-ethylhexanol (<NUM>-EH), but is not limited thereto.

The high-boiling point material may comprise one or more of hydroxypivalic hydroxypivalate (HPNE), trimethylpentanediol (TMPD), etc., but is not limited thereto.

In the present application, the hydrogenation reactor is a reactor comprising a catalyst in which copper is supported on a silicon oxide support as a fixed bed. Further, the hydrogenation reactor is be a fixed bed reactor (FBR) filled with the Cu/SiO<NUM> catalyst, and in this case, there is no need to separate the catalyst and a reaction product, and the reaction temperature and reaction pressure can be lowered than before so that the operation is stable and economical, and the catalyst replacement work is easy and the size of the reactor can be reduced so that there is an effect of greatly reducing the investment cost.

In an embodiment of the present application, at least a portion of a product after the hydrogenation reaction may be recirculated to the hydrogenation reactor. More specifically, a product comprising neopentyl glycol may be recirculated to the hydrogenation reactor, and heat generated in the hydrogenation reaction may be easily controlled accordingly. The hydrogenation reaction may have a recycle ratio (Feed/Recycle) of <NUM> to <NUM>/kg, <NUM> to <NUM>/kg, or <NUM> to <NUM>/kg, and there are effects of easily controlling the reaction heat and preventing a runaway reaction within the range. The "recycle ratio (Feed/Recycle)" refers to raw material supply flow amount to recirculation flow amount, unless otherwise specified.

In an embodiment of the present application, in the step of performing a hydrogenation reaction by injecting a hydroxypivaldehyde (HPA) solution and hydrogen into the hydrogenation reactor, the hydrogenation reaction may have a reaction temperature of <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>.

A process diagram of a method for producing neopentyl glycol according to an embodiment of the present application is schematically shown in <FIG> below, and a process diagram of a conventional method for producing neopentyl glycol is schematically shown in <FIG> below. As described in <FIG> below, the method for producing neopentyl glycol according to the present application comprises a step of performing a hydrogenation reaction by injecting a hydroxypivaldehyde (HPA) solution and hydrogen into a hydrogenation reactor, wherein the hydrogenation reactor is a reactor comprising a catalyst in which copper is supported on a silicon oxide support as a fixed bed, and comprises a step of adjusting the content of H<NUM>O contained in the hydroxypivaldehyde solution to <NUM>% by weight or less before the hydroxypivaldehyde solution is injected into the hydrogenation reactor.

In the method for producing neopentyl glycol according to the present application, the aging of the Cu/SiO<NUM> catalyst in the hydrogenation reaction can be slowed by adjusting the content of H<NUM>O contained in the hydroxypivaldehyde solution injected into the hydrogenation reactor to <NUM>% by weight or less.

Accordingly, the method for producing neopentyl glycol according to an embodiment of the present application can increase the period of use of the Cu/SiO<NUM> catalyst in the hydrogenation reaction, and can reduce the process cost due to catalyst purchase and catalyst replacement.

Hereinafter, Examples will be given and described in detail in order to describe the present application specifically. However, Examples according to the present application may be modified in various other forms, and the scope of the present application is not to be construed as being limited to Examples described in detail below. Examples of the present application are provided to more completely explain the present application to those of ordinary skill in the art.

An HPA solution (<NUM>% by weight of HPA, <NUM>% by weight of NPG, <NUM>% by weight of <NUM>-ethylhexanol, <NUM>% by weight of H<NUM>O, <NUM>% by weight of a high-boiling point material) was prepared.

After controlling the content of H<NUM>O in the HPA solution to <NUM>% by weight, it was injected into a fixed bed reactor (FBR) filled with a Cu/SiO<NUM> catalyst, and a hydrogenation reaction was carried out at <NUM> bar and <NUM> to produce neopentyl glycol. The content of H<NUM>O in the HPA solution was controlled using a distillation column.

The production process was carried out in the same manner as in Example <NUM> except that the content of H<NUM>O in the HPA solution injected into the FBR was controlled to <NUM>% by weight.

The production process was carried out in the same manner as in Example <NUM> except that the process of controlling the content of H<NUM>O in the HPA solution injected into the FBR was excluded. At this time, the content of H<NUM>O in the HPA solution injected into the FBR was <NUM>% by weight.

The reaction products produced in Examples and Comparative Example were analyzed by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) to measure Si concentrations, and the measurement results are shown in Table <NUM> below.

The ICP-OES analysis method is as follows.

<NUM>) About <NUM> of samples was accurately measured in a platinum crucible. <NUM>) The samples were heated on a hot plate to concentrate solvent components. <NUM>) <NUM> of nitric acid was put into the samples and heated. <NUM>) The samples were heated and dried. <NUM>) <NUM> of concentrated nitric acid was added to the samples, and <NUM>µl of hydrogen peroxide was added to the samples (the process was performed <NUM> to <NUM> times). <NUM>) When the organic materials were dissolved, <NUM> of nitric acid was put into the samples and heated. <NUM>) When the samples were clearly dissolved, they were diluted with <NUM> of ultrapure water. <NUM>) The samples were analyzed with ICP-OES (PERKIN-ELMER, OPTIMA 8300DV).

As the results of Table <NUM> above, it can be confirmed that there is a large amount of Si elution from the Cu/SiO<NUM> catalyst in the process for producing neopentyl glycol as in Comparative Example <NUM> so that it may cause a problem in long-term stability of the catalyst.

As shown in the above results, the method for producing neopentyl glycol according to an embodiment of the present application can slow the aging of the catalyst in the hydrogenation reaction by adjusting the content of H<NUM>O contained in the hydroxypivaldehyde solution injected into the hydrogenation reactor, wherein the hydrogenation reactor is a reactor comprising a catalyst in which copper is supported on a silicon oxide support as a fixed bed, to <NUM>% by weight or less. In particular, considering the content of Si eluted, it is more preferable to adjust the content of H<NUM>O contained in the hydroxypivaldehyde solution injected into the hydrogenation reactor to <NUM>% by weight or less.

Claim 1:
A method for producing neopentyl glycol, the method comprising a step of performing a hydrogenation reaction by injecting a hydroxypivaldehyde (HPA) solution and hydrogen into a hydrogenation reactor, and comprising a step of adjusting the content of H<NUM>O contained in the hydroxypivaldehyde solution to <NUM>% by weight or less before the hydroxypivaldehyde solution is injected into the hydrogenation reactor,
wherein the hydrogenation reactor is a reactor comprising a catalyst in which copper is supported on a silicon oxide support as a fixed bed.