CN101007764A - Method for producing fatty acid ester - Google Patents

Abstract

The present invention provides a method for producing a fatty acid ester, and a method for producing an alcohol that uses the fatty acid ester produced by the production method as a raw material for hydrogenation reaction. The manufacturing method of the fatty acid ester uses an adsorbent to adsorb sulfur in the raw fatty acid ester, and the adsorbent contains 10 to 85% by weight of a metal oxide selected from Ni and Cu based on the content of metal oxides in the total amount of the adsorbent. At least one of the metals, and the micropore capacity of the micropore diameter in the range of 20-200nm is 0.15-1.0mL/g.

Description

Method for producing fatty acid ester

technical field

The present invention relates to a method for producing a fatty acid ester, and a method for producing an alcohol using the fatty acid ester obtained by the production method as a raw material.

Background technique

Fatty acid esters usually contain a sulfur component of at least several mg/kg to several 10 mg/kg. The fatty acid esters mentioned here refer to esters of fatty acids and glycerol (triglycerides, diglycerides, monoglycerides), esters of fatty acids and alcohols with 1 to 22 carbon atoms (fatty acid alcohol esters), etc. Contains some free fatty acids. When alcohols are produced by hydrogenating these fatty acid esters in the presence of an ester reduction catalyst, the sulfur component contained in the fatty acid esters acts as a catalyst poison for the hydrogenation catalyst, and significantly reduces the catalyst activity. In particular, in the case of a fixed-bed continuous reaction, since the life of the catalyst becomes very short, frequent replacement of the catalyst is required, and the operating rate of the facility has to be reduced.

Furthermore, fatty acid esters are known as biodiesel fuels as a substitute for light oil, and in this application, fatty acid esters with a low sulfur content are required from the viewpoint of reducing sulfur oxides in exhaust gas.

Therefore, various studies have been conducted so far for the purpose of removing the sulfur component, which becomes a catalyst poison of a hydrogenation catalyst. For example, since sulfur compounds have relatively high boiling points, distillation is often used to reduce the sulfur concentration. However, it is impossible to remove all sulfur compounds by distillation, and in order to reduce the sulfur concentration to a level as low as 0.5 mg/kg, a large amount of originally required high-boiling components must be discarded, resulting in a significant decrease in yield.

In addition, in the petrochemical field, desulfurization catalysts mainly composed of molybdenum, cobalt, and nickel are used. In order to realize the desulfurization activity of this catalyst, a reaction temperature of 300° C. or higher is required. In order to improve the desulfurization activity, attempts are being made to specify the pore volume with a pore diameter in the range of 6 to 9 nm or 7 to 12 nm (JP-A2000-42413, JP-A2000-79343). However, the reaction temperature has not changed, and it still needs to be above 300°C.

On the other hand, there have been proposed methods of hydrodecomposing and adsorbing sulfur compounds in a hydrogen atmosphere using an adsorbent containing a metal such as Ni or Cu (JP-A5-978, JP-A6-57286).

However, the adsorbents of JP-A5-978 and JP-A6-57286 have insufficient activity, and in order to maintain the target adsorption performance, it is necessary to frequently replace expensive adsorbents, or to install large-scale adsorption equipment, which consumes the cost of adsorption treatment. Wait for the problem.

Furthermore, a nickel catalyst containing 87.5 to 99.9% by weight of nickel that can be used for solvent desulfurization is proposed in JP-A 2002-523230.

However, in the nickel catalyst of JP-A2002-523230, when the content of metals such as nickel is too high, it is worried that voids will be generated due to reduction to reduce the strength of the adsorbent, and it is difficult to ensure sufficient strength when filling the adsorbent after molding, causing dust. produce.

Contents of the invention

The present invention provides a method for producing a fatty acid ester with a low sulfur content, and a method for producing an alcohol using the fatty acid ester obtained by the production method as a raw material.

The inventors of the present invention conducted studies to solve the above-mentioned problems, and as a result, found that an adsorbent containing a specific amount of at least one selected from Ni and Cu and having a specific microporous structure, as a catalyst for desulfurization of fatty acid esters, It has high activity and can be used in the manufacture of fatty acid esters with low sulfur content.

The present invention provides a method for producing a fatty acid ester, and a method for producing an alcohol that uses the fatty acid ester produced by the production method as a raw material for hydrogenation reaction. The manufacturing method of the fatty acid ester uses an adsorbent to adsorb sulfur in the raw fatty acid ester, and the adsorbent contains 10 to 85% by weight (the content of the metal oxide in the total amount of the adsorbent) At least one metal, and the micropore capacity of the micropore diameter in the range of 20-200nm is 0.15-1.0mL/g.

According to the present invention, a fatty acid ester having a low sulfur content can be obtained, and an alcohol can be efficiently produced using the obtained fatty acid ester as a raw material.

Detailed ways

[Raw fatty acid ester]

As raw material fatty acid esters used in the present invention, esters of fatty acids and glycerol (triglycerides, diglycerides, monoglycerides), esters of fatty acids and alcohols with 1 to 22 carbon atoms (fatty acid alcohol esters) can be mentioned. )wait. Among them, examples of glycerides include animal triglycerides such as tallow and fish oil, vegetable triglycerides such as palm kernel oil, coconut oil, palm oil, soybean oil, and rapeseed oil, and diglycerides derived therefrom. esters, monoglycerides, etc. Among them, fatty acid esters having fatty acids having 8 to 22 carbon atoms as structural fatty acids are preferred, and fatty acid esters derived from vegetable glycerides are particularly preferred.

In addition, fatty acid alcohol esters can be produced by transesterification of the above-mentioned glycerides with alcohols with 1 to 22 carbon atoms, or esterification of fatty acids derived from the above-mentioned glycerides with alcohols with 1 to 22 carbon atoms. get. The alcohol used here is preferably a lower alcohol having 1 to 4 carbon atoms.

The transesterification reaction and esterification reaction can be implemented using a well-known method. For the reaction, either a continuous system or a batch system can be used, but the continuous reaction is advantageous when producing a large amount of ester. As the catalyst, a homogeneous base catalyst such as sodium hydroxide, potassium hydroxide, or sodium alkoxide is usually used, but a solid catalyst such as ion exchange resin, hydrated zirconia, aluminum phosphate, sulfuric acid-supported zirconium, or titanium silicon may also be used. When using a homogeneous base catalyst, the reaction is usually carried out under the following conditions. The reaction temperature is 30-90° C., preferably 40-80° C., and the reaction pressure is within the range of 0.5 MPa above and below normal pressure, preferably under normal pressure. In addition, from the viewpoint of cost and reactivity, the amount of alcohol used is preferably 1.5 to 10 mole times relative to glycerides. In addition, when free fatty acids are contained in glycerides, it is also effective to esterify the fatty acids in advance using an acid catalyst such as sulfuric acid or p-toluenesulfonic acid before transesterification with a base catalyst.

As the raw material fatty acid ester, it is preferable to use a fatty acid ester having a sulfur content of 50 mg/kg or less before treatment, more preferably 30 mg/kg or less, and even more preferably 10 mg/kg or less.

Examples of sulfur-containing compounds that can be effectively removed by the adsorbent of the present invention include aromatic sulfur-containing compounds such as mercaptans, thioethers, disulfides, thiocarboxylic acids, and thiophene.

[adsorbent]

The adsorbent used in the present invention contains at least one metal selected from Ni and Cu in an amount of 10% to 85% by weight (the content of metal oxide in the total amount of the adsorbent), and the micropore diameter is in the range of 20 to 200nm. The pore capacity is 0.15 to 1.0 mL/g, and at least one metal selected from Ni and Cu is preferably supported on the carrier.

From the viewpoint of adsorption capacity, the metal content in the adsorbent is 10% by weight or more, preferably 30% by weight or more, more preferably 40% by weight or more, and still more preferably 50% by weight or more. And, from the viewpoint of the strength of the adsorbent, it is 85% by weight or less, preferably 80% by weight or less.

From the viewpoint of adsorption capacity, the nickel metal content in the adsorbent is preferably 30% by weight or more, more preferably 40% by weight or more, and still more preferably 50% by weight or more. Furthermore, from the viewpoint of the strength of the adsorbent, it is preferably 80% by weight or less.

The metal content mentioned here is the content of metal oxides in the total amount of the adsorbent including the carrier or other components of the binder.

As the carrier, well-known carriers such as silica, alumina, silica-alumina, zeolite, diatomaceous earth, activated clay, titania, zirconia, and activated carbon can be used, preferably silica, alumina, silica-alumina, titania, and zirconia. , particularly preferably silicon dioxide and silicon aluminum.

The method of supporting at least one metal selected from Ni and Cu on the carrier is not particularly limited, and a coprecipitation method, an impregnation method, or a homogeneous kneading method may be used. Furthermore, these modulation methods may be used in combination. For example, when using the co-precipitation method, the following method can be used: any one or more aqueous solutions dissolved with water-soluble Ni salt or water-soluble Cu salt, the aqueous solution of the carrier substance, and the aqueous alkali metal solution are mixed to make the metal and the carrier Simultaneously, precipitation is carried out, and the obtained precipitation is washed, dried, and fired. Also, for example, when using the impregnation method, a method of immersing carrier powder in an aqueous solution in which any one or more of water-soluble Ni salt or water-soluble Cu salt is dissolved, followed by drying and firing may be employed.

The shape of the adsorbent can be appropriately selected from among powdery, granular, spherical or columnar shapes according to the adsorption treatment method, and according to the form of the reaction device. From the viewpoint of reducing the pressure loss when the fluid passes through the adsorbent, it is preferably granular or molded.

These sorbents are usually used after reductive activation with hydrogen. In addition, the adsorbent previously subjected to reduction activation and stabilization treatment may be used as it is or after reduction activation again.

The microporous structure of the adsorbent can be controlled by making various changes to catalyst preparation conditions such as precipitation conditions, drying conditions, molding conditions, and firing conditions. Compared with kerosene and light oil used in the petrochemical field, the raw material fatty acid ester used in the present invention is a highly polar and bulky molecule, and the technology in the petrochemical field cannot be directly used. The adsorbent used in the present invention is an adsorbent having a specific pore distribution that is suitable for desulfurization of raw fatty acid esters. That is, micropores with diameters in the range of 20 to 200 nm are effective for the desulfurization reaction of raw fatty acid esters, and an adsorbent with high desulfurization activity can be obtained by controlling the capacity of micropores within this range. From the viewpoint of exhibiting sufficient desulfurization activity, the capacity of micropores with a diameter in the range of 20 to 200 nm is 0.15 mL/g or more, preferably 0.20 mL/g or more, more preferably 0.25 mL/g or more. In addition, when used as a molded body, it is preferable that the volume density is high to a certain extent from the viewpoint that the reaction vessel can be designed to be miniaturized. Therefore, the capacity of micropores with a diameter in the range of 20 to 200 nm is 1.0 mL/g or less, It is preferably below 0.7 mL/g.

From the viewpoint of exhibiting sufficient desulfurization activity, the mode diameter of the pore diameter of the adsorbent of the present invention is preferably 20 nm or more, more preferably 30 nm or more. In addition, from the viewpoint of the strength of the adsorbent, it is preferably 200 nm or less, and more preferably 100 nm or less.

In addition, the pore volume and pore diameter used in the present invention were measured by mercury porosimetry. The maximum pressure of mercury intrusion was set to 207 MPa, and micropores larger than 6 nm were measured.

[Manufacturing method of fatty acid ester]

The method for producing a fatty acid ester of the present invention is to subject the raw material fatty acid ester obtained as described above to a sulfur adsorption treatment using the above-mentioned adsorbent to produce a fatty acid ester having a low sulfur concentration. It is also effective to perform distillation for the purpose of removing impurities or further reducing the sulfur concentration before or after the adsorption treatment.

As the adsorption treatment method, any method generally used, such as a suspension method or a fixed bed method, can be used. The continuous fixed bed regime is advantageous when processing large volumes.

When the adsorption treatment is carried out continuously in a fixed bed system, it is preferably carried out under the following conditions. The atmospheric gas is preferably hydrogen, and an inert gas may coexist. Examples of the inert gas include nitrogen, argon, helium and methane. The range of the flow rate of the atmospheric gas is preferably 0.1 to 300 times the ratio of the moles of hydrogen to the moles of the raw material fatty acid ester to be treated. The pressure of the atmospheric gas is preferably 0.01 to 50 MPa, more preferably 0.1 to 30 MPa.

From the viewpoint of obtaining a sufficient adsorption rate, the treatment temperature is preferably 40°C or higher, more preferably 50°C or higher. In addition, from the viewpoint of suppressing side reactions such as hydrogenolysis, it is preferably at most 200°C, more preferably at most 180°C.

From the standpoint of productivity, catalyst life, suppression of hydrogenolysis, etc., the flow rate of the raw material fatty acid ester is appropriately set, and it is preferably 0.1 or more in terms of reaction column volume ratio (LHSV) per hour. In addition, from the viewpoint of obtaining sufficient adsorption performance, the LHSV is preferably 5 or less.

Through the above-mentioned adsorption treatment of sulfur, when the raw material fatty acid ester is glycerides, the sulfur concentration after adsorption treatment can be made below 2 mg/kg; in addition, when the raw material fatty acid ester is fatty acid alcohol ester, the sulfur concentration after adsorption treatment can be made The sulfur concentration is below 0.6mg/kg. When the fatty acid ester subjected to the adsorption treatment is used as a raw material for alcohol production, it is very useful to reduce the activity reduction due to poisoning of the hydrogenation catalyst. The sulfur concentration of the glycerides after adsorption treatment is preferably 1.7 mg/kg or less, more preferably 1.5 mg/kg or less. In addition, the sulfur concentration of the fatty acid alcohol ester after adsorption treatment is preferably 0.3 mg/kg or less, more preferably 0.25 mg/kg or less, particularly preferably 0.20 mg/kg or less.

[manufacturing method of alcohol]

In the method for producing alcohol of the present invention, the fatty acid ester having a low sulfur content produced by the above-mentioned method of the present invention is used as a raw material, and subjected to a hydrogenation reaction.

As the hydrogenation catalyst, generally known copper-based or noble metal-based catalysts such as palladium or platinum are used. Examples of the copper-based catalyst include copper-chromium, copper-zinc, copper-iron-aluminum, copper-silica, and the like. In the presence of any of the above-mentioned catalysts, the hydrogenation reaction can be carried out by any reaction method generally used, such as a liquid phase suspension bed method or a fixed bed method.

When the reaction is carried out in a liquid-phase suspended bed system, the amount of the catalyst is preferably 0.1 to 20% by weight relative to the fatty acid ester, and can be arbitrarily selected within the range of obtaining a practical reaction yield according to the reaction temperature or reaction pressure. The reaction temperature is preferably 160 to 350°C, more preferably 200 to 280°C. The reaction pressure is preferably 0.1 to 35 MPa, more preferably 3 to 30 MPa.

When the reaction is carried out continuously in a fixed-bed system, a cylindrical shape, a catalyst shaped into a pellet shape, a spherical shape, or the like is used. The reaction temperature is preferably 130 to 300°C, more preferably 150 to 270°C. The reaction pressure is preferably 0.1 to 30 MPa. Considering productivity and reactivity, LHSV can be arbitrarily determined according to reaction conditions.

Example

Next, examples are described, but the scope of the present invention is not limited to the following examples.

In the following examples, the sulfur concentration was measured using a low-concentration sulfur analyzer 9000LLS manufactured by ANTEK Corporation. In addition, the measurement of the pore diameter and pore volume was performed using Pore Sizer 9320 manufactured by Micromeritics.

Preparation example of raw material fatty acid ester

0.30% by weight of NaOH and 10% by weight of methanol were added to palm kernel oil three times while removing the generated glycerin layer, and the reaction was carried out at 50° C. for 3 hours. After the reaction, the oil layer is washed with water to obtain palm kernel oil fatty acid methyl ester. Further, by distilling the obtained palm kernel oil fatty acid methyl ester, palm kernel oil fatty acid methyl ester having a sulfur concentration of 1.0 mg/kg was obtained. In the following examples, this fatty acid methyl ester was used as a raw material fatty acid ester.

Production Example 1 of Adsorbent

800 g of ion-exchanged water and 232 g of Ni(NO ₃ ) ₂ ·6H ₂ O were added to a 2 L separable flask, and the temperature was raised to 80° C. while stirring. A solution obtained by dissolving 33 g of JIS No. 3 water glass and 113 g of Na ₂ CO ₃ in 630 g of ion-exchanged water and heating to 80° C. was added thereto with stirring. After the addition, 24 g of Mg(NO ₃ ) ₂ ·6H ₂ O was added, and the resulting slurry was stirred at 80° C. for 1 hour, filtered, washed with water, and dried at 110° C. to obtain a precursor. Next, using alumina as a binder, the precursor was molded into a noodle shape, and then fired, reduced, and stabilized to obtain an adsorbent A with a diameter of 1.6 mm. The adsorbent A has a pore capacity of 0.361 mL/g with a pore diameter in the range of 20-200 nm.

Production Example 2 of Adsorbent

Add 840g of ion-exchanged water, 180g of Ni(NO ₃ ) ₂ 6H ₂ O, 22g of Cu(NO ₃ ) ₂ 3H ₂ O, 4g of γ-alumina, and 4.7g of 60% nitric acid into a 2L detachable flask , and the temperature was raised to 80°C while stirring. A solution obtained by dissolving 50 g of JIS No. 3 water glass and 118 g of Na ₂ CO ₃ in 570 g of ion-exchanged water and heating to 80° C. was added thereto with stirring. The resulting slurry was stirred at 80° C. for 1 hour, filtered, washed with water, and dried at 110° C. to obtain a precursor. Next, using alumina as a binder, the precursor was molded into a noodle shape, and then fired, reduced, and stabilized to obtain an adsorbent B with a diameter of 1.6 mm. The adsorbent B has a pore capacity of 0.325 mL/g with a pore diameter in the range of 20-200 nm.

Production Example 3 of Adsorbent

Add 1260g of ion-exchanged water, 108g of Ni(NO ₃ ) ₂ 6H ₂ O, 13g of Cu(NO ₃ ) ₂ 3H ₂ O, 2.4g of γ-alumina, and 2.8g of 60% nitric acid into a 2L detachable flask , and the temperature was raised to 80°C while stirring. A solution obtained by dissolving 30 g of JIS No. 3 water glass and 71 g of Na ₂ CO ₃ in 860 g of ion-exchanged water and heating to 80° C. was added thereto with stirring. The resulting slurry was stirred at 80° C. for 1 hour, filtered, washed with water, and dried at 110° C. to obtain a precursor. Next, using alumina as a binder, the precursor was molded into a noodle shape, and then fired, reduced, and stabilized to obtain adsorbent C with a diameter of 1.6 mm. The adsorbent C has a pore capacity of 0.182 mL/g with a pore diameter in the range of 20-200 nm.

Comparative Production Example 1 of Adsorbent

Adsorbent D was prepared in the same manner as in Production Example 3 except for prolonging the kneading time before molding. The adsorbent D has a pore capacity of 0.095 mL/g with a pore diameter in the range of 20-200 nm.

The metal content, pore capacity, and mode diameter of the pore diameters of the adsorbents A to D obtained in the above-mentioned Production Examples and Comparative Production Examples are summarized in Table 1 below.

Examples 1-3 and Comparative Example 1

Fill 180 mL of adsorbents A to D in a fixed bed reactor, and supply the palm kernel oil fatty acid obtained in the above preparation example at the same time from the upper part of the reactor at 900 mL/hr (LHSV=5) under the reaction conditions of 20 MPa and 90 °C Methyl ester is supplied with hydrogen at 1900 NL/hr for adsorption treatment. The residual sulfur concentration and desulfurization activity in the adsorption treatment palm kernel oil fatty acid methyl ester collected after passing through 1000 times of palm kernel oil fatty acid methyl ester are shown in Table 1. Here, the desulfurization activity was calculated using the following formula.

Desulfurization activity = log (sulfur concentration before adsorption treatment/sulfur concentration after adsorption treatment)

where "log" means the natural logarithm.

Table 1

Example Comparative example 1 1 2 3 The type of adsorbent A B C D Nickel content ^*1 (weight%) 76.1 62.2 63.7 63.7 Copper content ^*1 (weight%) - 8.4 7.8 7.8 Metal (nickel+copper) content ^*1 (weight%) 76.1 70.6 70.5 70.5 The micropore capacity of the adsorbent with the micropore diameter in the range of 20-200nm (mL/g) 0.361 0.325 0.182 0.095 Mode diameter of micropore diameter (nm) 61 50 33 18 Residual sulfur concentration (mg/kg) 0.10 0.11 0.17 0.32 Desulfurization activity 2.30 2.21 1.77 1.14

^* 1: The content of metal oxides in the total amount of adsorbent

Embodiment 4 (production example of alcohol)

Using a fixed bed reactor, the adsorption treatment and hydrogenation reaction of the palm kernel oil fatty acid methyl ester obtained in the above preparation example were continuously carried out. The fixed-bed reactor is equipped with two in-line reactors, the adsorbent A of 360mL is filled in the first reactor, and the titania of filling 360mL supports copper-zinc catalyst (composition: Cu=35%, Zn = 1.8%, TiO ₂ carrier 50%, shape: 3.2mmφ×3.2mm cylindrical shape). The adsorption condition of the first reactor is 20MPa, 90°C, and the flow rate of palm kernel oil fatty acid methyl ester is 260mL/h (LHSV=0.72). The sulfur concentration of palm kernel oil fatty acid methyl ester treated in the first reactor was 0.10 mg/kg.

The hydrogenation reaction conditions of the second reactor filled with the hydrogenation catalyst were a pressure of 20 MPa and a temperature of 210°C. After the hydrogenation reaction, the alcohol content in the obtained liquid was 96.8% on gas chromatography, and the saponification value was 4.7 mg-KOH/g.

Claims (7)

1. the manufacture method of a fatty acid ester is characterized in that:

Use sorbent material that the sulphur in the feedstock fat acid esters is carried out adsorption treatment, this sorbent material is at least a metal among Ni and the Cu of being selected from that benchmark contains 10～85 weight % with the content of the metal oxide in the sorbent material total amount, and the microvoid content of its micro-pore diameter in 20～200nm scope is 0.15～1.0mL/g.

2. the manufacture method of fatty acid ester as claimed in claim 1, it is characterized in that: the mode of the micro-pore diameter of described sorbent material directly is 20～200nm.

3. the manufacture method of fatty acid ester as claimed in claim 1 or 2, it is characterized in that: described sorbent material has the shape through overmolding.

4. the manufacture method of fatty acid ester as claimed in claim 1 or 2 is characterized in that: carry out described adsorption treatment under nitrogen atmosphere.

5. the manufacture method of fatty acid ester as claimed in claim 1 or 2 is characterized in that: carry out described adsorption treatment under 40～200 ℃.

6. the manufacture method of fatty acid ester as claimed in claim 1 or 2 is characterized in that: carry out described adsorption treatment with the fixed bed continuous mode.

7. the manufacture method of an alcohol is characterized in that: use the fatty acid ester of being made by claim 1 or 2 described manufacture method as raw material, carry out hydrogenation.