KR100868387B1 - Process of the catalyst preparation for the transesterification of vegetable oils or animal oils - Google Patents

Abstract

A method of manufacturing a catalyst for reacting transesterification of an animal.vegetable oil is provided to generate waste water including an inorganic salt by a corecipitation method by manufacturing the catalyst for reacting transesterification of the animal.vegetable oil by a milling method and to have a simple manufacturing step. Precursor slurry is manufactured by performing milling after dispersing a precursor by water. The precursor is separated from the precursor slurry and dried. A transesterification catalyst is obtained by heat-treating the dried precursor. The milling is a ball-mill, a dynomill or a sand mill. The precursor is a magnesium precursor which is a magnesium hydroxide, a magnesium oxide, a magnesium carbonate or a mixture thereof. The transesterification catalyst includes: an aluminium hydroxide, an aluminium oxide, an aluminum carbonate or an aluminum precursor which is a mixture thereof; and a zinc hydroxide, the zinc oxide, a zinc carbonate or a zinc precursor which is a mixture thereof.

Description

Process for producing catalyst for transesterification of animal and vegetable oils {Process of the Catalyst Preparation for the Transesterification of Vegetable Oils or Animal Oils}

The present invention relates to a method for producing a catalyst for transesterification reaction for synthesizing fatty acid alkyl esters from animal and vegetable oils.

Fatty acid alkyl esters are widely used as raw materials for diesel fuels and household fuels, natural affinity solvents, sulfuric acid derivatives of fatty alcohols, and sulfuric acid derivatives (biodegradable detergents and higher surfactants) of fatty amides. In particular, in the case of diesel fuel, it is usefully used as a material that satisfies the properties of cetane water compared to synthetic diesel fuel. However, stringent fuel oil quality standards should be free of high-boiling substances such as triglycelide, diglycelide, and monoglycelide, and less than 5% for corrosive fatty acids, less than 0.2% glycerin, and no trace metals. Must be satisfied. For household fuels, the above quality standards do not apply, but rather the quality standards for farm tractors and construction equipment.

When producing fatty acid alkyl esters from animal or vegetable oils, by-products of about 10-15% glycerin are produced by oil. High-purity glycerin is sold at high prices for various purposes, but the purification step is complicated, requiring a special vacuum distillation unit.

Most commercial processes synthesize esters and glycerin very easily, but with a high degree of purification which results in higher production costs. Sodium (Na), caustic, as shown in European Patent Nos. 301,634, US Pat. No. 3,852,315, WO 91/05034, Japanese Patent Laid-Open Nos. 10-182518 and JAOCS 61, 343, JAOCS 61, 1638 and JAOCS 63, 1375. Steels such as soda (NaOH), sodium carbonate (Na ₂ CO ₃ ), sodium alcoholate (Na alcoholate), potassium (K), potassium hydroxide (KOH), potassium carbonate K ₂ CO ₃ ), potassium alcoholate (K alcoholate) It is known to produce fatty acid methyl esters by reacting purified oils with dried alcohols under relatively mild reaction conditions at 50-80 ° C. and atmospheric pressure using a basic homogeneous catalyst. However, the above method goes through a multi-stage refining process for use as a fuel and high quality products. For example, alkaline compounds are found in glycerin and esters in processes using most basic homogeneous catalysts, and the crude esters are washed and dried. Crude glycerin is neutralized with soap and alcoholate components to make salts, the salt components are filtered, diluted glycerin is concentrated to remove water, and distilled glycerin is purified to high purity over 98%. In some cases, soluble salts are removed through an ion exchange resin, and then concentrated by distillation. The crude ester contains an excess of alcohol, so that some of the glycerin is dissolved in the ester layer and the ester and glycerin react to produce monoglycelides. Therefore, the alcohol must be distilled off. Most of the above processes operate in discontinuous batch reactors, and also suffer from low reactivity due to the hydrophilicity and low miscibility of the base catalyst.

Therefore, in order to improve the efficiency and productivity of the process, as described in Austrian patent PJ 1105/88, WO 91/05034, Korean Patent Publication 2003-0066246, using a homogeneous strong base catalyst, but applying a continuous reaction process, productivity and efficiency A method of increasing the number is being developed. However, these processes increase the efficiency and productivity of the reaction, but there is a problem inherently undergoing a complicated purification step to remove the base component.

Therefore, in order to fundamentally improve the shortcomings of the homogeneous catalyst process, many developments have been attempted for the process using the heterogeneous solid catalyst. Japanese Patent Laid-Open No. 1987-218495 discloses a method of using an ion exchange resin having an amine base as a catalyst. This technique has the characteristics of simple separation process because there is no problem of separation and recovery of catalyst, but it is low in practical use such as limiting the reaction temperature below 60 ℃ due to excessive use of alcohol, low activity and durability of ion exchange resin.

As an inorganic solid acid catalyst, Japanese Patent Laid-Open No. 1986-200943 using silica-alumina and zeolite, Japanese Patent Laid-Open No. 1986-236749 using aluminum oxide and iron oxide, and oxides of aluminum, gallium and iron are used. US Patent No. 6,407,269 is disclosed. However, most of these solid acid catalysts have low activity and react at a high temperature of 200 ° C. or higher, and there are many items to be improved in selectivity and reaction stability, such as by-products such as ether during the transesterification reaction.

Inorganic solid base catalysts have been studied in comparison with acid catalysts because of their relatively high activity and high selectivity. EP-B-0 198243 used aluminum and iron oxide catalysts. However, the supply rate of the reactants is LHSV (Linear hour space velocity) = 0.1hr ^-1 , the reaction productivity is very low, the purity of the ester is low 93-98% and there is a problem that the ether water of glycerin by-products.

British Patent GB-A-795 573, which uses zinc silicate as a catalyst, has a one-stage conversion of more than 85%, and glycerin is easily separated by 100% decantation, but the reaction temperature is 250-280 ° C and the reaction pressure is 100 atm. Since the above is necessary and part of the zinc catalyst produces zinc soap, there is a problem in that the washing of the ester and the further purification of glycerin are required.

In U.S. Patent No. 5,908,946, which uses a spinel-structured zinc aluminate (ZnAl ₂ O ₄ ) which is synthesized by high temperature firing of zinc oxide (ZnO) and aluminum oxide (Al ₂ O ₃ ), the reaction temperature is 220-250 ° C., reaction pressure. At 50-60 atmospheres, LHSV = 0.5-2hr ^-1 , the conversion is at least 99% and the yield is 94%, the product is depressurized to separate excess alcohol, the glycerin is decanted and distilled, so that the purity of the ester is 99 %, Glycerin purity of more than 99% was synthesized simply without complex purification. This method is a very good result in reactivity, but by using a relatively close to neutral neutral catalyst, there is a disadvantage that the reaction pressure and reaction temperature must be high in order to maintain high activity and selectivity.

In Korean Patent No. 0,644,246, which is based on magnesium oxide (MgO), zinc oxide (ZnO) and zinc aluminate (ZnAl ₂ O ₄ ), the milder reaction conditions are reaction temperature of 160-250 ℃, reaction pressure of 15-50 atmospheres, and LHSV. The conversion is at least 99% and ester yield 92% at = 0.1-3 hr ^-1 , and the product is decompressed to separate excess alcohol, the glycerin is decanted and distilled to yield 99.% ester purity and 98% glycerin purity. More than% products were synthesized simply without complex purification. Although the above solid catalyst is excellent in activity, it is co-precipitated by neutralizing aqueous solution of nitric acid such as magnesium nitrate, aluminum nitrate and zinc nitrate with basic aqueous solution such as caustic soda or sodium carbonate as catalyst raw material, and the extra sodium nitrate is deionized water. Since it is synthesized by washing with strict pH control and a large amount of difficult to decompose sodium nitrate waste water.

SUMMARY OF THE INVENTION An object of the present invention is to provide a catalyst having a uniform size, uniform shape, and homogeneous properties of catalyst particles in the production of a basic solid catalyst for producing fatty acid alkyl esters from animal and vegetable oils in high yield. Compared to the coprecipitation method, wastewater such as inorganic salts do not occur, and the manufacturing step provides a simple method.

The method for preparing a transesterification catalyst of the present invention comprises the steps of: (a) dispersing a precursor followed by milling to prepare a precursor slurry; (b) separating and drying the precursor in the precursor slurry; And (c) heat treating the dried precursor to obtain a transesterification catalyst, wherein the transesterification catalyst has the following formula (1).

(Formula 1)

xMgO, yZnO, ZnAl ₂ O ₄

In this case, x and y are molar ratios to ZnAl ₂ O ₄ , where x is 1 to 3, y is a number ranging from 0 to _2, and ZnAl ₂ O ₄ is a zinc aluminate having a spinel structure.

The precursor of step (a) is magnesium precursor, which is magnesium hydroxide, magnesium oxide, magnesium carbonate or a mixture thereof; Aluminum precursors which are aluminum hydroxide, aluminum oxide, aluminum carbonate or mixtures thereof; And zinc precursors that are zinc hydroxide, zinc oxide, zinc carbonate, or mixtures thereof. The magnesium precursor, the aluminum precursor, and the zinc precursor in the precursor slurry are preferably 20 to 60% by weight of the weight of the precursor slurry.

The milling of step (a) uses a ball mill, a dynomill or a sand mill, and is preferably carried out under the conditions of 10 to 40 vol% of precursor slurry and 10 to 40 vol% of the ball with respect to the volume of the mill. .

At this time, it is preferable that the particle size of the precursor is adjusted to 0.1 to 20㎛ by the milling step (a).

In addition, the slurry liquid obtained by separating the precursor in step (b) may be re-injected into step (a) to minimize the liquid discarded into the waste water.

The heat treatment of step (c) is preferably performed for 2 to 6 hours at a temperature of 700 to 1100 ℃.

Since the production method of the transesterification catalyst of the present invention is manufactured by the milling method compared to the conventional coprecipitation method, waste water such as nitrate is not environmentally friendly, and at the same time, the washing step is omitted, so the manufacturing step is simple and economical. The particle size of the prepared catalyst is uniform, the shape is constant, and there is an advantage of having an even composition.

Hereinafter will be described in detail the manufacturing method of the present invention. At this time, if there is no other definition in the technical terms and scientific terms used, it has a meaning commonly understood by those of ordinary skill in the art to which the present invention belongs, the gist of the present invention in the following description and the accompanying drawings Descriptions of well-known functions and configurations that may be unnecessarily blurred are omitted.

The method for preparing a transesterification catalyst of the present invention comprises the steps of: (a) dispersing a precursor followed by milling to prepare a precursor slurry; (b) separating and drying the precursor in the precursor slurry; And (c) heat treating the dried precursor to obtain a transesterification catalyst. The preparation has a feature, and the transesterification catalyst has the following formula (1).

(Formula 1)

xMgO, yZnO, ZnAl ₂ O ₄

In this case, x and y are molar ratios to ZnAl ₂ O ₄ , where x is 1 to 3, y is a number ranging from 0 to _2, and ZnAl ₂ O ₄ is a zinc aluminate having a spinel structure.

In the present invention, since the transesterification catalyst is manufactured by milling, waste water such as nitrate does not occur, and it is environmentally friendly. After milling to obtain fine particles of particles and uniform dispersion of particles of various substances constituting the catalyst, the milling liquid used for milling is separated and reused in the step (a) of preparing the precursor slurry to suppress the generation of waste water. You have an advantage.

Specifically, the transesterification catalyst represented by Chemical Formula 1 according to the present invention adds a slurry containing a precursor of a catalyst and a dispersion medium such as a ball to a mill and mills to disperse the precursor and After atomization, the milled precursor is separated, dried, and calcined at 800 to 1000 ° C. for 2 to 6 hours to prepare a mixed metal oxide of magnesium oxide, zinc oxide and spinel structured zinc aluminate.

At this time, the precursor is magnesium precursor which is magnesium hydroxide, magnesium oxide, magnesium carbonate or a mixture thereof; Aluminum precursors which are aluminum hydroxide, aluminum oxide, aluminum carbonate or mixtures thereof; And zinc precursors that are zinc hydroxide, zinc oxide, zinc carbonate, or mixtures thereof. It is preferable to use magnesium hydroxide, aluminum hydroxide, and zinc hydroxide as precursors in terms of even dispersion by milling.

Preferably, the transesterification catalyst of Formula 1 prepared using magnesium hydroxide, aluminum hydroxide and zinc hydroxide as a precursor is an active ingredient, and magnesium oxide (MgO) is a molar ratio of 1 to 3 based on zinc aluminate, and zinc oxide. (ZnO) is preferably a molar ratio of 0 to 2. More preferably, the molar ratio of magnesium oxide is 1.5 to 2.5, and the molar ratio of zinc oxide is 0.5 to 1.5. When the molar ratio of magnesium oxide is 3 or more, the activity at the initial stage of the reaction is high, but the deactivation proceeds soon and the conversion rate is reduced. In addition, when the molar ratio of magnesium oxide is 1 or less, and the molar ratio of zinc oxide is 2 or more, the activity is low, the conversion rate is low, and the reaction temperature and pressure must be increased, and the reaction stability is decreased in the long term.

In the step (a), preferably, a hydroxide powder of magnesium, aluminum and zinc is used as a precursor to be dispersed and stirred in distilled water from which ions are removed. In this case, the size of the hydroxide powder is preferably 1 to 100 μm, The concentration is preferably 20 to 60% by weight. When the weight of the precursor is 20% by weight or less or the weight of the dispersion precursor is 60% by weight or more, it is difficult to control the atomization of the particles by milling and it is difficult to obtain uniform dispersion. In addition, the volume of the precursor slurry based on the volume of the mill to be milled is preferably 10 to 40% by volume of the container, the total volume of the ball used is preferably 10 to 40% by volume. The size of the ball used for milling depends on the type of mill. In the case of a ball mill, the size of the ball is 3 to 50 mm, and in the case of a dyno or sand mill, the size of the mill is preferably 1 to 3 mm. The material of the ball is preferably alumina, zirconium silicate, zirconia or the like. The above milling conditions are conditions optimized to minimize contamination by the milling process and to obtain uniform dispersion of precursor particles.

The particle | grains in the precursor slurry after dispersion are 0.1-20 micrometers, Preferably it is 0.2-10 micrometers. If the particle size is 0.1 μm or less, it becomes difficult to separate the liquid and particles from the precursor slurry. If the particle size is 20 μm or more, dispersion of the precursor particles becomes insufficient, that is, it is impossible to obtain homogeneously mixed precursor particles. This reduces the activity of the catalyst.

Subsequently, in step (b) according to the present invention, the precursor is separated and dried from the precursor slurry obtained in step (a), and the separation may be a solid-liquid separation method that is commonly used, and may be used for filtration, sedimentation, and centrifugation. Separation methods can be used. At this time, the slurry liquid obtained after separating the precursor from the precursor slurry as described above can be reused to make the precursor slurry of step (a), it can significantly reduce the amount of waste water. After the milling is completed, the recovered precursor is preferably dried for 5 to 30 hours at 100 to 120 ℃.

Subsequently, in step (c) according to the present invention, the dried precursor is calcined in step (b), and in firing, the dried precursor is molded by extrusion, tableting, or by a method of supporting the refractory carrier. It is preferable to bake at 2 to 6 hours at 1 to 1100 ° C, preferably 800 to 1000 ° C. If the sintering temperature is too high, more than 1100 ℃ metal oxide particles are sintered to decrease the catalytic activity, if the sintering temperature is too low below 700 ℃, the zinc aluminate of the spinel structure is not produced, the reaction stability is reduced and the conversion rate is lowered.

Transesterification catalyst to be produced according to the present invention may be used to react the animal and vegetable oils and C lower alcohols _1-4 producing the fatty acid alkyl ester, wherein the animal and vegetable oil are soybean oil, rapeseed oil, sunflower seed oil, corn oil, Palm oil and tallow, or a combination of two or more thereof. C _1-4 lower alcohols are methyl alcohol, ethyl alcohol, propyl alcohol and butyl alcohol or a combination of two or more thereof.

The transesterification reaction using the catalyst of the present invention is characterized by a continuous reaction using a fixed bed reactor. As a reaction method, several high pressure reactors and decanters can be used continuously. For example, switch to about 85% in the first reactor, evaporate unreacted alcohol in the second reactor, cool to decanter the glycerin, and feed the alcohol evaporated in the third reactor to complete the reaction. . Finally, excess alcohol is distilled off and the alkyl ester and glycerin are separated in a decanter.

The reaction conditions are supplied deuldorok the range of the LHSV (liquid hourly space velocity, the liquid space velocity) of the oil is 0.1~3.0hr ^-1, preferably 0.2~2.0hr ^-1, and the weight ratio of alcohol / oil is 0.2 to 2.0, Preferably it is 0.5-1.5. The reaction temperature is carried out at 160 to 250 ° C., preferably 180 to 230 ° C., and the reaction pressure is 15 to 50 atm, preferably 20 to 40 atm, and the catalyst is charged to the reactor and then pressurized to the reaction pressure with nitrogen gas. After raising the temperature, the reactor was heated to the reaction temperature, and the reaction was carried out by supplying animal, vegetable oil and alcohol to the catalyst layer.

If the reaction temperature does not exceed 250 ° C, the color of the reaction starting oil and the produced ester are the same, and colorless transparent glycerin is simply obtained by decantation. In addition, esters and glycerin may be further purified by treatment with resin or activated clay and activated carbon. It is also washed with glycerin in the presence of alcohol to lower the content of monoglycerides contained in the ester.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the spirit and scope of the present invention. Modifications and variations are possible.

(Example 1)

Transesterification Catalyst 2MgO · 1ZnO · ZnAl Using Milling Method ₂ O ₄ Manufacture

23.3 g of magnesium hydroxide (Mg (OH) ₂ , Samchun Chemical, Code M0065, Lot. 121506), 31.2 g of aluminum hydroxide (Al (OH) ₃ , Junsei Chemical, Code 39025-1501, Lot. 6K1100) and zinc hydroxide (Zn (OH) ₂ , Junsei Chemical, Code 39020-1501, Lot.2K1356) After adding 39.8 g of a precursor to 250 ml of deionized water and stirring, the stirred dispersion and 100 ml of 3 mm size zirconia balls in a 800 ml ball mill vessel, 100 ml of 10 mm zirconia balls were added and milled for 10 hours to prepare precursor slurry. As a result of analyzing the prepared precursor slurry with a particle size analyzer, the particle size of the precursor was 0.2 to 8 μm, and the average particle size was 2 μm.

The prepared precursor slurry was filtered to recover the milled precursor particles, which were dried at 100 ° C. for 10 hours. The dried precursor powder was analyzed by X-ray diffraction spectroscopy (XRD) to confirm that it was magnesium hydroxide, zinc oxide, and aluminum hydroxide compound (FIG. 1). In particular, the diffraction peaks of zinc oxide and magnesium hydroxide are smaller in size than aluminum hydroxide, and the crystals appear to be uniformly dispersed in the state of being atomized by milling and undergoing crystallization. The dried precursor powder was press-molded, then crushed to 20-40 mesh, sorted, and calcined at 900 ° C. for 3 hours to prepare a transesterification catalyst.

Were mixed in 2MgO · ZnO · ZnAl ₂ O ₄ oxide, as shown, the prepared transesterification catalyst in Figure 2 was analyzed by X- ray diffraction spectroscopy, the ZnAl ₂ O ₄ was found to have a spinel structure. As can be seen from the results of FIG. 2, there was no unreacted precursor material. In addition, the relative intensities of diffraction picks by MgO, ZnO, and ZnAl ₂ O ₄ materials were 100%, 53%, and 98%, corresponding to the diffraction intensities of the reference peaks indicated in the lower part of FIG. It can be seen that the ZnAl ₂ O ₄ particles are very uniformly mixed. As a result of analyzing the surface structure of the catalyst with a scanning electron microscope (SEM) as shown in FIG. 3, crystals having a size of 100 nm (0.10 μm) are uniformly formed and some densification processes due to high temperature baking It proceeds and exists in the form of lumps, but the basic crystals are kept the same size.

The transesterification reaction was performed using the catalyst prepared to evaluate the properties of the transesterification catalyst prepared in Example 1 as follows.

Transesterification reaction

3.0 ml (1.5 g) of the transesterification catalyst prepared in Example 1 was filled in a stainless tube reactor having a diameter of 1/2 inch and a length of 25 cm and a heating section of 20 cm, and the reaction temperature of 200 ℃, 30 atm Under the conditions, rapeseed oil was reacted with LHSV (liquid feed rate) = 0.5hr ⁻¹ and methyl alcohol was fed to the reactor with LHSV = 0.5hr ⁻¹ . The product was separated by distillation of methyl alcohol, and decanted to separate glycerin and ester. The ester product was analyzed by GC (gas chromatography) equipped with Rtx-65-TG column. The reaction results are expressed in weight percent, summarized in Table 1 below. Magnesium, zinc and aluminum contained in esters and glycerin were quantitatively analyzed by acid decomposition. The contents of magnesium, zinc and aluminum in each sample were 5 ppm or less, respectively.

Table 1

Example 1 except that magnesium hydroxide, aluminum hydroxide, zinc hydroxide was quantified so that x and y are 1.2 and 1.8 (Example 2), 2.6 and 0.4 (Example 3), respectively. In the same manner, a transesterification catalyst was prepared, and as a comparative example, magnesium hydroxide, aluminum hydroxide, zinc hydroxide so that the composition of the xMgO-ZnO-ZnAl ₂ O ₄ catalyst was in the range of 1 to 3 and y was 0 to 2 Comparative Examples 1 to 4 were carried out in the same manner as in Example 1 except for quantifying. The catalysts prepared in Examples 2 to 3 and Comparative Examples 1 to 4 were reacted for 100 hours using the same reaction conditions as those of the transesterification reaction. The reaction result after 100 hours of reaction was put together in following Table 2.

Table 2

Using the catalyst prepared in Example 1 using palm oil instead of rapeseed oil, ethyl alcohol instead of methyl alcohol, using the same reaction conditions as the transesterification reaction except that the reaction temperature is 220 ℃ The reaction was carried out for 100 hours. The reaction result after 100 hours of reaction was put together in following Table 3.

Table 3

As can be seen from the results of Tables 1 to 3, the transesterification catalyst prepared by the production method of the present invention can stably produce fatty acid alkyl esters from animal and vegetable oils in high yield under mild conditions for a long time. As can be seen from 1, the transesterification catalyst synthesized by the milling method of the present invention has high activity and maintains higher activity for a longer time than the xMgO.yZnO.ZnAl ₂ O ₄ catalyst synthesized by the coprecipitation method.

In order to clarify the superiority of the method for preparing the transesterification catalyst by the milling method of the present invention, the transesterification catalyst (xMgOyZnOZnAl ₂ O ₄ , x is 1 to 3, y is 0 to 2 range) was prepared, followed by transesterification.

(Comparative Example 5)

Transesterification catalyst 2MgO.1ZnO.ZnAl by heat mixing ₂ O ₄ Manufacture

23.3 g of magnesium hydroxide (Mg (OH) ₂ , Samchun Chemical, Code M0065, Lot. 121506), 31.2 g of aluminum hydroxide (Al (OH) ₃ , Junsei Chemical, Code 39025-1501, Lot. 6K1100) and zinc hydroxide (Zn (OH) ₂ , Junsei Chemical, Code 39020-1501, Lot. 2K1356) 39.8 g of a precursor was added to a 1,000 ml beaker with 400 ml of deionized water and stirred at 80 ° C. for 10 hours to prepare a precursor slurry. As a result of analyzing the prepared precursor slurry with a particle size analyzer (Particle size analyser), the precursor particle size was 1 to 40㎛, the average particle size was 20㎛. The prepared precursor slurry was similar to the hydroxide precursor obtained by the coprecipitation method, and the prepared precursor slurry was filtered to recover the precursor powder, which was dried at 100 ° C. for 10 hours.

The dried precursor powder was analyzed by X-ray diffraction spectroscopy (XRD) to confirm that it was magnesium hydroxide, zinc oxide, and aluminum hydroxide compound (FIG. 4). However, although the diffraction peaks of aluminum hydroxide and magnesium hydroxide are smaller in size than zinc oxide, amorphous crystals of aluminum hydroxide and magnesium hydroxide proceed by heat mixing, but zinc oxide seems to be dispersed in a state of maintaining a crystal. The dried precursor powder was press-molded, then crushed to 20-40 mesh, sorted, and calcined at 900 ° C. for 3 hours to prepare a transesterification catalyst.

By analyzing the production transesterification catalyst by X- ray diffraction spectroscopy result was a mixture of 2MgO · ZnO · ZnAl ₂ O ₄ oxide, as shown in Figure 5, the ZnAl ₂ O ₄ was found to have a spinel structure. In addition, as can be seen from the results of FIG. 4, there was no unreacted precursor material. However, while the relative intensities of the diffraction picks by MgO, ZnO and ZnAl ₂ O ₄ materials are 100%, 85% and 74%, the diffraction intensities of the reference peaks shown in the lower part of FIG. 4 coincide with MgO and ZnAl ₂ O ₄ , Since the diffraction intensity of ZnO is relatively large, the ZnO crystal is relatively large, and the uniformity of 2MgO, ZnO and ZnAl ₂ O ₄ particles of the prepared catalyst is relatively low. In addition, as a result of analyzing the surface structure of the catalyst using a SEM scanning electron microscope as shown in FIG. 6, crystals having a size of 100 to 1,000 nm (0.10 to 1.0 μm) are non-uniformly generated.

The transesterification reaction was carried out as follows using the prepared catalyst to evaluate the properties of the transesterification catalyst prepared in Comparative Example 5.

Transesterification reaction

The reaction was carried out in the same manner as the transesterification reaction of Example 1, except that the catalyst prepared in Comparative Example 5 was used. The reaction results are expressed in weight% and summarized in Table 4 below. Magnesium, zinc and aluminum contained in esters and glycerin were quantitatively analyzed by acid decomposition. The contents of magnesium, zinc and aluminum in each sample were 5 ppm or less, respectively.

Table 4

As can be seen from Table 4, the transesterification catalyst synthesized by the heat mixing method has a large decrease in activity with reaction time, and a large decrease in selectivity of methyl ester. This is because the catalyst particles prepared by the heat mixing method have lower uniformity and reaction stability than the milling method.

1 is an X-ray diffraction result of the precursor separated and dried in the precursor slurry in Example 1 of the present invention,

2 is an X-ray diffraction result of the transesterification catalyst prepared in Example 1 of the present invention,

3 is a scanning electron micrograph of the transesterification catalyst prepared in Example 1 of the present invention,

4 is an X-ray diffraction result of the precursor separated and dried in the precursor slurry prepared in Comparative Example 5 of the present invention,

5 is an X-ray diffraction result of the transesterification catalyst prepared in Comparative Example 5 of the present invention,

6 is a scanning electron micrograph of the transesterification catalyst prepared in Comparative Example 5 of the present invention.

Claims (8)

In the production method of the animal and vegetable oils and C _{1 ~ 4} is reacted with lower alcohol to for producing a fatty acid alkyl ester of formula (1) transesterification catalyst, (a) water dispersing the precursor and then milling to prepare a precursor slurry; (b) separating the precursor from the precursor slurry and drying the precursor; And (c) heat treating the dried precursor to obtain a transesterification catalyst. (Formula 1) xMgO, yZnO, ZnAl ₂ O ₄ In this case, x and y are molar ratios to ZnAl ₂ O ₄ , where x is 1 to 3, y is a number ranging from 0 to _2, and ZnAl ₂ O ₄ is a zinc aluminate having a spinel structure. The method of claim 1, The precursor of step (a) is magnesium precursor, which is magnesium hydroxide, magnesium oxide, magnesium carbonate or a mixture thereof; Aluminum precursors which are aluminum hydroxide, aluminum oxide, aluminum carbonate or mixtures thereof; And zinc precursors which are zinc hydroxide, zinc oxide, zinc carbonate, or mixtures thereof. The method of claim 2, Magnesium precursor, aluminum precursor and zinc precursor in the precursor slurry is a method for producing a transesterification catalyst, characterized in that 20 to 60% by weight of the precursor slurry. The method of claim 1, The milling of step (a) is a ball mill, a dynomill or a sand mill manufacturing method of the transesterification catalyst, characterized in that. The method of claim 1, Method of producing a transesterification catalyst, characterized in that carried out under the conditions of 10 to 40% by volume of precursor slurry and 10 to 40% by volume of the ball in the milling step of the milling step. The method of claim 2, Method of producing a transesterification catalyst, characterized in that the particle size of the precursor is adjusted to 0.1 to 20㎛ by the milling step (a). The method of claim 1, Method for producing a transesterification catalyst, characterized in that the slurry liquid obtained by separating the precursor in step (b) is re-injected in step (a). The method of claim 1, The heat treatment of step (c) is carried out at a temperature of 700 to 1100 ℃ 2 to 6 hours, characterized in that the preparation method of the transesterification catalyst.

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