KR20150125446A - Preparation method of Trimethylol propane ester for vegetable insulating oil - Google Patents

Abstract

The present invention relates to a process for producing trimethylolpropane ester, and more particularly, to a process for producing trimethylolpropane ester, which comprises: a first step of preparing a KF / HAP catalyst carrying KF on a hydroxyapatite (HAP) as a catalyst support; And a second step of esterifying trimethylol propane (TMP) with oleic acid in the presence of the KF / HAP catalyst to produce trimethylolpropane ester (TMP-ester). A process for preparing a useful trimethylolpropane ester is disclosed.
Unlike other catalysts, the trimethylolpropane ester does not form by-products such as oleate after the synthesis of trimethylolpropane ester by using a KF / HAP catalyst, thereby enhancing the reaction stability, It is easy to recover, and the process is simple, so mass production is easy.
Since the trimethylolpropane ester produced is a vegetable component, it can be easily decomposed by microorganisms existing in nature in a natural state. Therefore, it is easy to decompose by microorganisms at the time of leakage or disposal, and the flash point and pour point characteristics are 268 & 37.5 캜, both of which show relatively high performance, and thus can be usefully used as a vegetable electric insulating oil in a transformer or the like.

Description

Preparation method of trimethylol propane ester for vegetable insulating oil [0002]

The present invention relates to a method for preparing a trimethylolpropane ester useful as a vegetable electric insulating material, and more particularly, to a method for producing a trimethylolpropane ester using a KF / HAP catalyst.

One of the biggest issues in the world since the 20th century is energy issues, including environmental issues. Energy is not only a source of life, but also has a decisive influence on the quality of human life, such as transportation, heating and cooling, and the production and use of industrial products. As the population increases and the standard of living improves, the demand for energy is increasing. In the case of Korea, where energy dependence of foreign countries is close to 97%, securing of energy is an important issue. In the case of oil-producing countries in the south-west Asia and the UK, Norway and Denmark, which possess the North Sea oilfield, the energy independence rate is relatively high. However, the energy of these countries is based on depleted fossil fuels. The imbalance also affects the stability of the international political economy.

Nevertheless, Korea's energy use per capita is very high at 5.22 (TOE / person), compared with 1.31 for Japan, 1.56 for Germany and 2.45 for the US, . This energy problem is not a problem only in Korea, but a problem that is being highlighted all over the world. Therefore, interest in the development of renewable alternative energy is increasing. In addition, climate change conventions have been linked to environmental issues as well as energy.

Among these renewable energies, wind power generation is now the most used with solar energy. Wind power has been shown to be the most technologically advanced and economical, making it a competitive investment in many countries. Although wind turbine research has been started on land wind power generation, it is moving toward offshore wind power generation to overcome these shortcomings due to lack of installation space and noise. In the case of offshore wind power generation, there is an advantage in that a sufficient amount of energy can be obtained by using abundant offshore wind resources and a large site compared to onshore wind power generation.

Inside the Nacelle of the wind turbine is a gear box for transmitting power, a generator for generating power by receiving the power, an inverter for changing the DC power to AC power, And a transformer for adjusting the size of the transformer. As wind power has expanded from land to sea, components are demanding performance that meets geographical installation conditions. Among them, the transformer is located outside the nacelle in the offshore wind turbine, but on the inside of the nacelle due to the geographical constraint in the offshore wind turbine. In the case of a transformer, the electric insulating oil is contained in the inside of the transformer. The electric insulating oil using the mineral oil as the raw material is not suitable for the marine environment due to the risk of marine pollution when leaking and the extreme temperature change It is known. Therefore, the development of electric insulation oil for transformers that can be used for offshore wind power generators should be able to develop sustainable offshore wind power generation.

Electrical insulating oil has been required to have a performance corresponding to the tendency of various electric devices to be higher in voltage and capacity, and according to the demand, various additives are added mainly based on mineral oil and developed and used as an insulating oil satisfying the requirements Has come.

As an example thereof, Korean Patent Publication No. 1994-0003803 discloses an insulating oil excellent in dielectric breakdown voltage characteristics by adding a compound selected from a linear hydrocarbon compound having a double bond to a mineral oil insulating oil, a seed oil, and an ester compound, Korean Patent Publication No. 63-4286 discloses a technique for improving the dielectric breakdown voltage characteristic by adding a fluorine-based organic compound to a mineral oil-based insulating oil, and in JP-A-69-84714, a surfactant of phosphoric acid ester is added to mineral oil Technology.

As described above, the development of the technology for improving the dielectric breakdown voltage characteristics by adding various additives with the mineral oil as the main raw material has led to much improvement in the electrical characteristics of the mineral oil electric insulating oil, which contributed to the extension of the life of the electric insulating oil In the case of electric insulating oil, the electric insulating oil deteriorated from the transformer or the like should be recovered after sufficient use, and the recovered oil should be used or dismantled in combination with new insulating oil.

In the case of electric insulating oil which can not be regenerated and is discarded due to its use, it is not easily burned due to an antioxidant added as an additive, etc., and there is a problem that pollution such as dioxin is generated when environmental pollution occurs.

Accordingly, in recent years, there has been a demand for development of environmentally friendly electric insulating oil. According to such a request, US Pat. No. 5,958,851 discloses a process for hydrogenating or methyl esterifying soybean oil containing oleic acid as its main raw material, And the technology to use the trans-shafts is disclosed.

In addition, US Pat. No. 5,949,017 discloses the use of a trans-oil by mixing 75% or more of oleic acid triglyceride, vegetable oil composed of unsaturated fatty acids having 16 to 22 carbon atoms, saturated fatty acids having 16 to 22 carbon atoms and an antioxidant, Examples of vegetable oils having such an oleic acid content include sunflower oil, olive oil, safflower oil, and the like.

The insulating oil known from the above-mentioned U.S. Patent No. 5,949,017 contains an ester compound such as oleic acid triglyceride, and when it comes into contact with water at a high temperature, the stability against hydrolysis is low. However, it has an effect of improving the biodegradability by mixing vegetable oil with mineral oil and the like.

However, it is a fact that it is not used only as vegetable oil for high voltage electrical insulation oil. In order to withstand high pressure as a vegetable oil as electric insulating oil, it is necessary to secure a high flash point and a low pour point.

On the other hand, the ester group (-COO-) of the polyol ester has a faster rate of biodegradation than the conventional mineral oil structure because the polyol ester oil leaks to the outside, especially to the ocean, as the first attack point of the microorganism. In addition, if the structure has a linear carbon chain structure, the biodegradation rate is faster than that of the branched carbon chain structure. This is because the metabolism of microorganisms is easily decomposed into linear and prey. Therefore, if the polyol ester is a linear polyol ester after the synthesis reaction, the risk of leaking can be reduced.

The present inventors have made efforts to produce a polyol ester for use as a vegetable electric insulating oil. As a result, oleic acid as a fatty acid and trimethylolpropane (TMP) as a polyol were selected, and KF / HAP The preparation of trimethylolpropane ester, which can simultaneously enhance the flash point and pour point characteristics, has been completed using a catalyst.

In order to solve the above problems, it is an object of the present invention to provide a process for producing trimethylolpropane ester using a KF / HAP catalyst.

The present invention also provides a trimethylolpropane ester prepared by the above process.

In order to solve the above problems, the present invention provides, as one aspect,

A first step of preparing a KF / HAP catalyst carrying KF on hydroxyapatite (HAP) as a catalyst support; And a second step of esterifying trimethylol propane (TMP) with oleic acid in the presence of the KF / HAP catalyst to produce trimethylolpropane ester (TMP-ester). And a process for producing the useful trimethylolpropane ester.

Also preferably, the KF / HAP catalyst is characterized in that 30-40 wt% of KF is supported on the HAP.

Preferably, the reaction molar ratio of trimethylolpropane to oleic acid is 1: 3.

Preferably, the amount of the KF / HAP catalyst added is 2 to 10% by weight based on oleic acid.

Preferably, the esterification reaction temperature of trimethylolpropane and oleic acid is 200-300 占 폚.

Further, the esterification reaction time of trimethylolpropane and oleic acid is preferably 3-5 hours.

According to another aspect of the present invention,

A first step of preparing a KF / HAP catalyst carrying KF on hydroxyapatite (HAP) as a catalyst support; And a second step of esterifying trimethylolpropane (TMP) with oleic acid in the presence of the KF / HAP catalyst to produce trimethylolpropane ester (TMP-ester). An electrically insulating useful trimethylol propane ester is provided.

As described above, the method of producing trimethylolpropane ester according to the present invention does not form by-products such as oleate after the synthesis of trimethylolpropane ester by using a KF / HAP catalyst, thereby improving the reaction stability , Catalyst recovery is easy by using a heterogeneous catalyst, and the process is simple and mass production is easy.

Since the trimethylolpropane ester produced is a vegetable component, it can be easily decomposed by microorganisms existing in nature in a natural state. Therefore, it is easy to decompose by microorganisms at the time of leakage or disposal, and the flash point and pour point characteristics are 268 & 37.5 캜, both of which show relatively high performance, and thus can be usefully used as a vegetable electric insulating oil in a transformer or the like.

1 is an FE-SEM image of a KF / HAP catalyst prepared according to one embodiment of the present invention.
Figure 2 shows the XRD pattern of a KF / HAP catalyst prepared according to one embodiment of the present invention.
Figure 3 shows the XRD pattern near the KF peak (2? = 33.6 ㅀ) of the KF / HAP catalyst prepared according to one embodiment of the present invention.
4 is a photograph showing Zn-oleate of trimethylolpropane ester prepared by using ZnO as a catalyst according to a comparative example of the present invention.
FIG. 5 is a photograph showing trimethylolpropane ester prepared using a multi-component catalyst according to a comparative example of the present invention. FIG.
FIG. 6 is a graph showing the change of the flash point of the TMP ester prepared with respect to the change of the KF supporting ratio according to an embodiment of the present invention. FIG.
FIG. 7 is a graph showing the change of the pour point of the TMP ester prepared for the change of the KF supporting ratio according to an embodiment of the present invention. FIG.

Hereinafter, the present invention will be described in detail.

The process for producing trimethylolpropane ester according to the present invention comprises

(a) a first step of preparing a KF / HAP catalyst carrying KF on hydroxyapatite (HAP) as a catalyst support; And

(b) a step of esterifying trimethylol propane (TMP) with oleic acid in the presence of the KF / HAP catalyst to produce trimethylolpropane ester (TMP-ester).

In the method for producing trimethylolpropane ester according to the present invention, the first step is a step of preparing a KF / HAP catalyst.

Generally, in the esterification reaction, an acid catalyst such as sulfuric acid, hydrochloric acid, or an alkali catalyst such as sodium hydroxide, sodium methoxide, or potassium hydroxide is widely used. In the case of an acid catalyst, however, a layer separation phenomenon occurs, The reaction rate is slow, and in order to accelerate the reaction, it is necessary to vigorously stir and to remove the water outside the system, and in the case of using the alkali catalyst, the reaction can be obtained at a relatively high yield and the reaction can be stably carried out However, there is a problem that the yield is lowered if attention is not paid due to the saponification of the vegetable oil by the alkali.

Further, in the case of using a metal oxide catalyst, which is excellent in reactivity when used in the esterification reaction in the conventional literature, there is a problem of forming by-products such as oleate in the production of trimethylolpropane ester thereafter.

However, in the case of the KF / HAP catalyst according to the present invention, by using a HAP which is stable in the synthesis reaction as a support, KF as an active catalyst is supported to produce a catalyst. Byproducts are not formed during the production of trimethylolpropane ester, Ester (see Experimental Example 1).

At this time, it is preferable to use the KF / HAP catalyst having 35-45 wt% of KF supported on HAP, which has the largest pore size of the catalyst in the KF content and the conversion rate of oleic acid is more than 90% (See Experimental Example 3).

In addition, in the method of supporting KF on hydroxyapatite (HAP) as a catalyst support in the production of the KF / HAP catalyst, both the simple deposition method and the excess solution deposition method can be used. However, since the two methods do not show much difference in reactivity, In mass production, it is preferable to carry out KF by an excess solution impregnation method considering the simplicity of the process and economical efficiency (see Experiment Example 5).

Next, in the second step, trimethylol propane (TMP) is esterified with oleic acid using the KF / HAP catalyst prepared in the first step to prepare trimethylolpropane ester (TMP-ester).

In the above step, the reaction molar ratio of trimethylolpropane to oleic acid is preferably 1: 3. If oleic acid is used in excess, the reactivity is lowered due to the steric effect of oleic acid. there is a problem.

The addition amount of the KF / HAP catalyst is preferably 2 to 10% by weight based on the oleic acid. If the amount of the KF / HAP catalyst is less than 2% by weight, the esterification reaction itself does not occur If it is more than 10% by weight, the reactivity does not increase with the increase of the catalyst, and the catalyst is wasted.

Furthermore, the esterification reaction temperature of trimethylolpropane and oleic acid is preferably 200-300 ° C, and the reaction time is preferably 3-5 hours.

In the esterification reaction of trimethylolpropane and oleic acid, when the reaction temperature is lowered to 200 ° C or less, the esterification reaction is not completely carried out, so that the residual fatty acid and the polyol are present in a mixed state, Considering that the boiling point of fatty acid oleic acid is 360 ° C, the maximum reaction temperature should be set to 300 ° C or less in order to prevent evaporation of fatty acid.

When the reaction time is less than 3 hours under such a temperature condition, the reaction is not completely carried out due to the low esterification and there is a problem in the flash point and the pour point. If the reaction is carried out for more than 5 hours, It is preferable to terminate the reaction within the range of 3 hours to 5 hours, since it causes deterioration in the color and properties of the product caused by the coloring and acts as a factor of cost increase.

In addition, the present invention provides a vegetable electrically insulating useful trimethylolpropane ester prepared by the above production method.

The trimethylolpropane ester is characterized in that it is prepared using the KF / HAP catalyst according to the invention, and the common description of both inventions is omitted in order to avoid the excessive complexity of the specification according to the repetitive description.

Since the trimethylolpropane ester according to the present invention does not form by-products such as oleate after the synthesis of the trimethylolpropane ester by using the KF / HAP catalyst, unlike the other catalysts (Experimental Example 1, See FIG. 5), the reaction stability is enhanced, catalyst recovery using a heterogeneous catalyst is easy, and the process is simple, thereby facilitating mass production.

Since the trimethylolpropane ester produced is a vegetable component, it can be easily decomposed by microorganisms existing in nature in a natural state. Therefore, it is easy to decompose by microorganisms at the time of leakage or disposal, and the flash point and pour point characteristics are 268 & 37.5 캜, both of which show relatively high performance, and thus can be usefully used as a vegetable electric insulating oil in a transformer or the like.

Hereinafter, the present invention will be described in detail with reference to examples, but these examples should not be construed as limiting the scope of the present invention.

EXAMPLES Preparation of trimethylolpropane (TMP) ester using KF / HAP catalyst

1. Preparation of KF / HAP catalyst

<1-1> Preparation of Catalyst Support

Hydroxyapatite (HAP) was synthesized by the precipitation method as the catalyst support. Specifically, a 0.2 mol / L solution of (NH ₄ ) ₂ HPO ₄ was dropwise added at a rate of 2 mL / min to a 0.2 mol / L solution of Ca (NO ₃ ) ₂ .4H ₂ O and reacted. The stirring speed during the reaction was 200 rpm and the temperature was maintained at 70 캜. After the addition was completed, the pH of the mixture was adjusted to 10.5 by adding ammonia water. The reaction was carried out at 70 DEG C for 2 hours and aged at room temperature for 24 hours after completion of the reaction. After filtration, the sample was washed with distilled water. The washed sample was dried at 110 ° C. for 12 hours and then calcined at 900 ° C. for 4 hours to prepare HAP.

&Lt; 1-2 > Carrying KF on HAP support

The active catalyst was supported on a support using two methods, a wet impregnation method and an excess wet impregnation method.

The method of producing the simple deposition method used in the present invention is as follows. After the preparation of the HAP was completed, the metal salt (KF) was added to the HAP in an amount sufficient to be absorbed into the pores of the fired HAP by using each of KF 10 wt%, KF 20 wt%, KF 30 wt% and 40 wt% Respectively. To use this as a catalyst, it was dried at 110 ° C for 12 hours and then calcined at 400 ° C for 4 hours. HAP, S-KF (20%) / HAP, S-KF (30%) / HAP and S-KF (40%) / HAP depending on the loading ratio of KF Respectively.

The method of preparing the excess solution impregnation method used in the present invention is as follows. First, the loading amount of KF is calculated based on the mass of HAP, and the amount of KF is dissolved in the excess amount of distilled water. HAP is added to KF aqueous solution, and the temperature is gradually raised in a vacuum state, and the mixture is heated at a temperature at which the aqueous solution does not overflow for about 4 hours to completely evaporate the water. The prepared catalyst was dried in an oven at 105 DEG C for about 12 hours, and then calcined at 400 DEG C for 4 hours. HAP, E-KF (20%) / HAP, E-KF (30%) / HAP and E-KF (40%) / HAP depending on the loading ratio of KF Respectively.

2. TMP ester synthesis

0.59 mol of trimethylol propane (TMP, 97%, sigma-aldrich) and 1.77 mol of oleic acid (> 90%, sigma-aldrich) were placed in a glass 2 L round bottom flask and the reaction temperature was adjusted to 200 Deg.] C, and then 2 wt% of the KF / HAP catalyst prepared above was added thereto based on oleic acid. The reaction was carried out at a molar ratio of 3: 1 (quantitative) of the reaction mixture, oleic acid and trimethylol propane. The reaction temperature and stirring speed were kept constant and the reaction time was 3-5 hours. After completion of the synthesis, the catalyst was separated through a pressure - reducing filter to calculate the conversion of fatty acids.

<Catalytic Analysis>

A. Field emission scanning electron microscope (FE-SEM) analysis

The particle shape and the element distribution state of the prepared catalyst were measured using a Field Emission Scanning Electron Microscope (SU8020, Hitachi, Japan) equipped with an element analyzer (Energy Dispersive Spectroscopy, EDS) , And the resulting image is shown in Fig.

In FIG. 1, (a) shows the HAP before the firing process, and (b) shows the HAP after the firing process. (c) is E-KF (10%) / HAP, (d) is E-KF (20%) / HAP, 40%) / HAP, and (g) E-KF (50%) / HAP.

As shown in FIG. 1, the HAP was observed to be deformed into a columnar shape with both ends being sharp before firing, and a columnar shape with both ends rounded and flared after firing. This is inferred from the fact that as the sintering progresses, grains are formed by sintering of the particles. The size of the HAP particles formed was about 300 nm in width and 200 nm in height. Also, as the amount of KF was increased, the shape of the particles was changed from a hexagonal columnar shape to a circular shape. This is because KF is distributed evenly on the surface of HAP as KF loading increases.

In addition, KF was well supported on the HAP scaffold since no particle of KF was found in the electron microscope image. The average particle size of the KF supported HAP catalyst was 172 nm.

B. X-ray Diffraction (XRD) analysis

Analysis was performed using an X-ray diffractometer (XRD, D / MAC 2500-V / PC, Rigaku, Japan) to determine the crystal shape and size of the prepared catalyst. At 20 mA, Cu-Kα (λ = 1.5405 Å) was used to measure the scan speed at 5 ° C / min and the 2θ value in the range of 20-90 ㅀ. The main peak half width (FWHM) of the catalyst in the result of XRD analysis was measured, and the particle size of the catalyst was confirmed by the Scherrer equation of the following equation (1).

Where L is the crystal size, λ is the wavelength of the X-radiation, θ is the Bragg angle, and B is the half-width (FWHM, radian).

The results are shown in Fig. 2 and Fig.

As shown in FIG. 2 and FIG. 3, it was confirmed that the crystallinity decreases as the amount of KF supported increases. The decrease in the crystallinity of the catalyst is consistent with the result that the shape of the catalyst is deformed from a hexagonal columnar shape to a circular shape as previously confirmed in an electron microscope (FE-SEM) image.

The XRD peak of HAP prepared was mostly between 2θ = 20-60 으며 and confirmed by the hydroxyapatite spectrum of JCPDS 9-0432. Compared with the KF-supported catalyst, there was no difference in peak, and the characteristic peak of KF (2θ = 33.6 ㅀ) was not observed. This means that KF is well dispersed and does not form large clusters. The XRD patterns of KF-loaded catalysts indicated that each catalyst had a single phase crystal.

C. Acid-base characterization and pore volume / diameter analysis

Ammonia temperature programmed desorption method _{(NH 3 -Temperature Programmed Desorption, NH} 3 -TPD, Autochem II 2920, Micromeritics, USA) and carbon dioxide temperature programmed desorption method _{(CO 2 -Temperature Programmed Desorption, CO} 2 -TPD, Autochem II 2920, Micromeritics, USA ) Was used to analyze the acid-base characteristics of the catalyst. The measurement method of ammonia TPD is as follows. The sample is injected into a U-shaped quartz fixed bed reactor. Pure helium gas (He gas) was blown at a rate of 10 mL / min while being heated to 200 ° C at a rate of about 10 ° C / min and maintained for 1 hour for pretreatment. After the pretreatment, the temperature was cooled to 50 DEG C and maintained for 10 minutes. Thereafter, pure ammonia gas (NH ₃ gas) was flowed again at a rate of 50 mL / min for 1 hour to adsorb the catalyst. At the end of the adsorption, the heavily adsorbed ammonia was removed at 100 ° C for 1 hour while flowing helium. After cooling to 30 ° C, the temperature of the catalyst was elevated to 800 ° C at a rate of 10 ° C / min, and the amount of ammonia desorbed was measured to analyze the acid characteristics of the catalyst. The carbon dioxide TPD was also measured under the same conditions and the amount of carbon dioxide removed was analyzed to analyze the base characteristics of the catalyst.

Nitrogen adsorption / desorption isotherm analysis (surface area analyzer, ASAP2020, Micromeritics Instruments Corp., USA) was performed to measure the pore volume and diameter of the prepared catalyst. Specifically, the sample was taken to be 1.0 g or less and pre-treated at a temperature raising rate of 10 캜 / min at a temperature of 250 캜 for 4 hours in a nitrogen atmosphere, and then cooled to room temperature. The pretreated specimens were annealed at 100 ℃ for 12 hours, and adsorption isotherms were obtained by proceeding nitrogen adsorption - desorption at 77 K. Total pore volume and diameter were measured in the range of P / P ㅀ = 0.05-0.2. Total pore volume and pore size were calculated as adsorption amount at P / P ㅀ = 0.995.

The results of the analysis are shown in Table 1 below.

catalyst Surface area
(m ² / g) Pore volume
(cm ³ / g) Pore diameter
(nm) Acid density ^A
(mmol / g) Base point density ^B
(mmol / g) ratio
(Acid / base point) HAP 7.3053 0.011243 6.15580 0.13 0.12 1.08 E-KF (10%) / HAP 3.4224 0.009811 11.46654 0.37 0.51 0.73 E-KF (20%) / HAP 8.6624 0.026831 12.38949 0.57 0.51 1.12 E-KF (30%) / HAP 5.9472 0.017109 11.50704 0.67 0.58 1.16 E-KF (40%) / HAP 4.7833 0.020979 17.54323 0.61 0.51 1.20 E-KF (50%) / HAP 3.3270 0.009536 11.46456 0.49 0.63 0.78 A: TPD by NH ₃
B: by the TPD of CO ₂

As shown in Table 1, in the case of the KF / HAP catalyst prepared according to the present invention, the acid point was measured to be larger than the base point of the catalyst and the ratio of the acid point / base point was found to be KF (40%) / HAP The ratio of catalyst was the highest because of the high acidity.

As the pore volume and pore diameter increased, the pore size was similar with increasing KF loading, but the pore size was found to be the maximum at 40 wt% loading of KF.

Based on the results of the above two experiments, it can be seen that the ratio of acid / base point increases with the addition of KF.

&Lt; Comparative Example 1-9 > Preparation of TMP ester using other catalyst

MgO, Al2O3, W / phosphoric acid, Li / CaO, Mg / Ca / Y, Zn (7) / Al (3), which are good in reactivity when used in the esterification reaction instead of KF / The reaction time was 3 hours, the reaction temperature was 160 ° C, the molar ratio of fatty acid to TMP was 1: 6, the ratio of fatty acid to the catalyst was 1: TMP ester was prepared in the same manner as in Example except that the dose was 2 wt%.

Experimental Example 1 Effect of Catalyst on TMP Ester Synthesis

In order to investigate the effect of catalyst on TMP ester synthesis, the following experiment was conducted.

The ester conversion of fatty acid was measured in the case of using KF (20%) / HAP as a catalyst or in the case of using a catalyst of Comparative Example according to an embodiment of the present invention, and the state of the prepared TMP ester was observed. And Figs. 4-5.

catalyst Total acid value of oleic acid
(mgKOH / g) Conversion rate of oleic acid
(%) KF (20%) / HAP 120.738 36.38 ZnO 32.404 82.93 MgO 75.963 59.98 Al ₂ O ₃ 151.62 20.11 W / phosphoric acid 93.207 50.89 Li / CaO 31.363 47.54 Zn (7) / La (3) 26.171 57.15 Zn (7) / Al (3) 29.23 51.11 Zn (3) / Al (1) / La (1) 100.454 47.07 Mg / Ca / Y 104.362 45.01

As shown in Table 2, conversion of oleic acid by using each catalyst was as follows: ZnO was 82.93%, MgO was 59.98%, Al ₂ O ₃ was 20.11%, and the conversion rate of oleic acid Was the highest. However, it was confirmed that ZnO and oleic acid reacted to form a wax-like substance called Zinc-oleate as shown in FIG. Also, it was confirmed that wax-like substances were synthesized in the same manner as ZnO even when the remaining metal oxide catalysts were used. Therefore, it is considered that the metal oxide catalyst is not suitable for the TMP ester synthesis reaction because it reacts with oleic acid to synthesize a wax-like substance.

As shown in Table 2, conversion of oleic acid to each catalyst was 50.89% for W / phosphoric acid, 47.54% for Li / CaO, (47.15%) of Zn (7) / La (3), 51.11% of Zn (7) / Al (3), 47.07% of Zn . However, as shown in FIG. 5, since the color of the compound after the reaction is black, oxidation of oleic acid seems to be accelerated when a binary catalyst is used. When using a multi-component catalyst, the multi-component catalyst reacts with oleic acid, which is a raw material, to produce magnesium oleate, lanthanum oleate, alumium oleate, and potassium oleate, respectively. Therefore, it was expected that the above-mentioned multi-component catalyst would not be suitable for the esterification reaction.

On the other hand, when using the KF / HAP catalyst according to the present invention, oleate was not formed unlike the other catalysts. Therefore, it can be seen that the stability of the TMP ester synthesis reaction can be secured by using the KF / HAP catalyst according to the present invention.

<Experimental Example 2> Effect of fatty acids on the synthesis of TMP ester

In order to investigate the effect of the amount of fatty acid in the synthesis of TMP ester, fatty acid was injected in a fixed amount and excess amount with respect to TMP to confirm the reactivity according to the steric effect of the fatty acid. As a result of measuring the amount of water (H ₂ O) generated as byproducts during the reaction, 12 mL was generated when the fatty acid was reacted in a quantitative manner, and 9 mL was generated when the reaction was excessive. It was confirmed that when the fatty acid was reacted in a quantitative manner, about 3 mL more was produced than when the fatty acid was reacted in excess.

After the completion of the reaction, the acid value was measured and the reactivity was quantitatively confirmed to be lower than 120.738 mgKOH / g when the fatty acid was reacted with the quantitative amount of 74.164 mgKOH / g. Based on these results, the conversion rate for each reaction was 60.92% for fatty acid, and about twice as high as 36.38% for fatty acid.

Therefore, it is preferable that the amount of the fatty acid is adjusted by adding the fatty acid in the TMP ester synthesis.

&Lt; Experimental Example 3 > Effect of KF loading rate in the catalyst during TMP ester synthesis

In order to investigate the effect of KF support ratio in the catalyst during TMP ester synthesis, experiments were carried out while increasing the loading ratio of the active catalyst KF from 10 wt% to 20 wt%, 30 wt% and 40 wt% And the conversion ratios were measured and shown in Table 3 below.

KF content
(weight%) Acid value
(mgKOH / g) Conversion Rate
(%) 10 23.92 87.39 20 23.93 87.39 30 21.70 88.57 40 18.62 90.19 50 19.23 89.87

As shown in Table 3, the reactivity of each catalyst was 23.92 mgKOH / g when the amount of supported KF was 10% by weight, 23.93 mgKOH / g when KF was 20% %, 18.62 mg KOH / g when KF was 40% by weight, and 19.23 mgKOH / g when KF was 50% by weight. As the KF loading ratio increased, the acidity decreased and the conversion rates increased to 87.39%, 87.39%, 88.57%, 90.19% and 89.87%, respectively. In particular, when KF 40 wt%, the conversion ratio was measured to be the highest.

The E-KF / HAP catalyst loaded with KF 40 wt% had the largest pore diameters in comparison with the other catalysts. When the active sites of the catalyst were compared, the ratio of the acid sites to the base sites was the highest. Therefore, it was confirmed that the higher the ratio of the acid sites and the base sites, the higher the conversion of oleic acid.

Experimental Example 4 Effect of Reaction Temperature on TMP Ester Synthesis

In order to investigate the effect of the reaction temperature on the TMP ester synthesis, the KF / HAP catalyst supporting 40 wt% of KF having the highest conversion rate in the previous experiment was used to compare the conversion rates according to the reaction temperature. Table 4 shows the results.

Reaction temperature
(° C) Acid value
(mgKOH / g) Conversion Rate
(%) 150 88.327 53.46 200 26.365 86.11 250 9.535 94.98 300 7.483 96.06 350 2.402 98.73

As shown in Table 4, the acid value was 88.327 mgKOH / g, 26.365 mgKOH / g, 9.535 mgKOH / g, 7.483 mgKOH / g, and 2.402 g as the reaction temperature was increased to 150 ° C., 200 ° C., 250 ° C., 300 ° C. and 350 ° C. mgKOH / g. &lt; tb &gt;&lt; TABLE &gt; Also, it was confirmed that the conversion ratios of the respective compounds increased to 53.46%, 86.11%, 94.98%, 96.06%, and 98.73%, respectively. Since the esterification reaction is an endothermic reaction, the reactivity increases as the reaction temperature increases. Also, it has a high reactivity when the removal of water, which is a byproduct produced during the reaction, is facilitated. As can be seen from the results, the higher the reaction temperature, the better the endothermic reaction and the higher the reaction temperature, and the higher the reaction temperature, the better the removal of water produced during the reaction, and the higher the reaction temperature, the higher the reactivity. However, considering that the boiling point of oleic acid used is 360 ° C, the maximum reaction temperature should be set to 300 ° C or less in order to prevent evaporation of the fatty acid.

&Lt; Experimental Example 5 > Effect of KF deposition method on TMP ester synthesis

To investigate the effect of KF deposition method on TMP ester synthesis After carrying out the method of supporting the active catalyst KF on the support chain HAP using the wet impregnation method and the excess wet impregnation method, the conversion ratio of oleic acid to the supported ratio was measured The results are shown in Table 5 below.

catalyst Simple deposition method Excess solution impregnation method KF (10%) / HAP 86.91% 87.39% KF (20%) / HAP 87.11% 87.39% KF (30%) / HAP 92.03% 88.57% KF (40%) / HAP 88.27% 90.19% KF (50%) / HAP 89.19% 90.04%

As shown in Table 5, when KF was loaded by the simple immersion method and the excess solution impregnation method, the conversion rate of oleic acid was increased with the loading ratio. Especially, TMP ester synthesis using KF supported catalyst by simple deposition method showed the highest conversion rate of oleic acid to be 92.03% when 30% by weight of KF was supported, and the catalyst supporting KF by excess solution impregnation method , The highest conversion of oleic acid was found to be 90.19% when 40 wt% of KF was supported.

The experimental results show that the catalytic activity of the catalyst prepared by using the excess solution impregnation method is generally high, but the points showing the highest conversion rates are different in each method, and the conversion rate at the peak is rather simple It was confirmed that the catalyst prepared by the immersion method was better.

However, the conversion rate of fatty acids is within the error range in both the simple immersion method and the excess solution immersion method, and accordingly, the accuracy according to the KF loading amount is similar. However, the difference in the conversion ratio to the peak was different depending on the loading amount of KF, which appears to be a result of the size of the pores after the catalyst production. This is because the catalyst prepared by the simple deposition method has a maximum pore size at 30% by weight of KF and the maximum pore size at 40% by weight of the catalyst prepared by the excess solution deposition method.

Considering the simplicity and economy of the process, considering the process aspect that requires mass production in synthesis of TMP ester for use as an electric insulating oil for a transformer of offshore wind turbine generator, KF It is preferable to carry the support.

&Lt; Experimental Example 6 > Insulation characteristics according to input amount of oleic acid

The electrical insulating oil properties of the TMP ester prepared according to the amount of oleic acid were measured by the following method.

The flash point of the TMP ester was measured in accordance with ASTM D 92. The vapor generated from a gas or a volatile liquid is mixed with air to form a flammable or mixed gas, That is, the lowest temperature to be printed was measured.

The pour point of the TMP ester was measured according to ASTM D 97. It is necessary to prevent lowering of the cooling function, which is the inherent function of the insulating oil, by lowering the pour point because the insulating oil is hardened by the hardening of the insulating oil in the cold oil or the winter season.

The measurement results are shown in Table 6 below.

Oleic acid Acid value
(mgKOH / g) Conversion Rate
(%) flash point
(° C) Pour point
(° C) Excessive 120.738 36.38 220 5 dose 74.164 60.92 232 -2.5

As shown in Table 6, when the oleic acid, which is a fatty acid, was added and reacted in a fixed amount, the result showed a flash point of 232 ° C, which was measured to be about 10 ° C higher than the flash point 220 ° C when an excessive amount of the acid was added. The results of the pour point measurement showed that the characteristics of the electric insulating oil were better when the fatty acid was added at a fixed rate of -2.5 ° C when the fatty acid was added and the fatty acid was added at the same temperature as the flash point at 5 ° C. This means that the reaction proceeded by the addition of a fixed amount means that the reactivity of the reactants is better than that of the fatty acids and TMP esters in the excess of the fatty acid.

<Experimental Example 7> Insulation characteristics according to KF loading ratio

In the KF / HAP catalyst, the electric insulating oil characteristics of the TMP ester prepared according to the KF supported ratio were measured, and the results are shown in FIG. 6 and FIG.

FIG. 6 is a graph showing the change of the flash point of the TMP ester produced with respect to the change of the KF supporting ratio, and FIG. 7 is a graph showing the change of the pour point of the TMP ester prepared with respect to the change of the KF supporting ratio.

As shown in FIGS. 6 and 7, it was confirmed that the characteristics of the flash point and the pour point were improved as the KF loading ratio was increased, thereby enhancing the electrical insulation characteristics. Specifically, when the amount of KF was 40 wt%, the flash point was the highest at 268 ° C and the pour point was the lowest at -27.5 ° C. As a result of the above-mentioned reactivity, the same results as those obtained when the KF loading was 40 wt% were obtained. It is considered that the higher the reactivity is, the more the insulating properties are strengthened as well.

Therefore, the TMP ester has excellent performance near the flash point of 300 DEG C or higher and the pour point of -20 DEG C or less, which is the vegetable oil-insensitive oil standard value when manufactured using the KF / HAP catalyst having a KF loading of 40 wt% Can be used.

<Experimental Example 8> Insulation characteristics according to reaction temperature

In order to investigate the effect of insulation characteristics according to the reaction temperature in the TMP ester synthesis, the KF / HAP catalyst supporting 40 wt% of KF showed the highest conversion rate in the previous experiment. And the results are shown in Table 7 below.

Reaction temperature
(° C) flash point
(° C) Pour point
(° C) 150 242 0 200 254 -17.5 250 264 -37.5 300 268 -37.5 350 262 -30.0

As shown in Table 7, it was confirmed that the flash point increased from 242 ° C to 262 ° C as the reaction temperature increased from 150 ° C to 350 ° C, and the pour point decreased from 0 ° C to -30.0 ° C to enhance the insulation characteristics.

The flash point was the highest at 268 ℃ when the reaction temperature was 300 ℃ and the lowest was found at -37.5 ℃ when the reaction temperature was 250 ℃ and 300 ℃. Therefore, when considering that the boiling point of oleic acid is 360 ° C, it is preferable to set the reaction temperature to 300 ° C or less to prevent vaporization of oleic acid.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (7)

A first step of preparing a KF / HAP catalyst carrying KF on hydroxyapatite (HAP) as a catalyst support; And
And a second step of esterifying trimethylolpropane (TMP) with oleic acid in the presence of the KF / HAP catalyst to produce trimethylolpropane ester (TMP-ester). A process for producing trimethylolpropane ester. The method according to claim 1,
Wherein the KF / HAP catalyst is characterized in that 30-40 wt% of KF is supported on the HAP. The method according to claim 1,
Wherein the reaction molar ratio of trimethylolpropane to oleic acid is 1: 3. The method according to claim 1,
Wherein the addition amount of the KF / HAP catalyst is 2 to 10% by weight based on the weight of the oleic acid. The method according to claim 1,
Wherein the esterification reaction temperature of trimethylolpropane and oleic acid is 200-300 占 폚. The method according to claim 1,
Wherein the esterification reaction time of trimethylolpropane and oleic acid is 3-5 hours. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt; A vegetable electrically insulating useful trimethylol propane ester prepared by any one of claims 1 to 6.

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