CN103641707B - Method for preparation of sebacic acid by castor oil compound cracking - Google Patents

Abstract

The invention discloses a method for preparation of sebacic acid by castor oil compound cracking. The method includes: subjecting the castor oil compound to saponification treatment and acidification treatment to obtain ricinoleic acid, adding 40-50% by mass of an alkaline solution, a loaded catalyst and a diluent into the ricinoleic acid to undergo a cracking reaction at 250-320DEG C for 3-6h, keeping the alkaline solution and the castor oil compound being in a volume ratio of 1-3:1, with the dosage of the loaded iron catalyst accounting for 5-10% of the mass of the castor oil compound, and keeping the diluent and the castor oil compound in a volume ratio of 2-6:1; filtering the reaction liquid after reaction, adjusting the pH of the filtrate to 6 by 3-6mol/l hydrochloric acid or sulfuric acid, subjecting the solution to layering, taking the water phase, and adding 3-6mol/l hydrochloric acid or sulfuric acid to adjust the pH to 2, thus obtaining sebacic acid. The method provided by the invention adopts the loaded catalyst, which catalyzes cracking of the castor oil compound in a reaction system containing a concentrated alkaline solution and liquid paraffin under high temperature to prepare sebacic acid. The product yield is high, and the catalyst is easy to recover and reuse.

Description

A method for preparing sebacic acid by cracking castor oil compounds

technical field

The invention relates to a method for cracking castor oil compounds to prepare sebacic acid.

Background technique

Sebacic acid is an important chemical raw material, used in the production of engineering plastics, epoxy resin curing agent, synthetic grease, sebacic anhydride, high temperature resistant lubricating oil, artificial fragrance, etc. Esters of sebacic acid are used in the manufacture of cold-resistant plasticizers dimethyl sebacate, dibutyl sebacate, di-n-hexyl sebacate, dioctyl sebacate and diisooctyl sebacate, sebacate Diisodecyl diacid. Due to the wide application of sebacic acid and the relatively large demand in domestic and foreign markets.

At present, due to the rich resources of castor oil in my country and the low price, the preparation of sebacic acid in my country is mainly obtained by cracking castor oil. The production process is mainly to crack ricinoleic acid under the conditions of diluent phenol and an appropriate amount of alkali, without using a catalyst , the yield of sebacic acid is only 35.7% to 44%. For example, Zhou Hongshun et al. used Pb ₃ O ₄ as a catalyst and liquid paraffin as a diluent, which greatly increased the yield of sebacic acid, and used relatively clean liquid paraffin as a diluent to avoid the generation of phenol-containing wastewater from the source. But because Pb ₃ O ₄ is poisonous, it will affect the quality of the product and pollute the environment. Wang Yanxiong et al. improved the catalyst on this basis, using environmentally friendly Fe ₂ O ₃ powder as the catalyst, and liquid paraffin as the diluent, and the yield was equivalent to that of Pb ₃ O ₄ as the catalyst. However, when Fe ₂ O ₃ powder is used as a catalyst for the cracking reaction, the iron content in the obtained product is too high, and the catalyst cannot be recycled.

At present, the application of supported catalysts is becoming more and more common. In the preparation process of existing supported catalysts, the carrier is usually impregnated with soluble iron salts, dried and directly calcined. The process of using it to catalyze cracking castor oil to prepare sebacic acid is carried out under concentrated alkali and high temperature conditions. Due to the inconsistent acidity and alkalinity of the catalyst and the cracking reaction, and under high temperature and strong alkali environment, the existing supported catalyst It is unstable when encountering a strong base, resulting in a low yield of the final product.

Contents of the invention

Aiming at the problems that the existing Fe ₂ O ₃ powder is used as a catalyst for cracking castor oil compounds to produce sebacic acid, the catalytic efficiency is low, the iron content in the product is high, and the catalyst cannot be recycled. The object of the present invention is to provide a preparation method of a supported catalyst and a method for preparing sebacic acid by catalytically cracking castor oil compounds. The supported catalyst prepared by the method is used for catalytically cracking castor oil to prepare sebacic acid. The advantages of high efficiency and reduced iron content in the product, and the supported catalyst can be recycled.

In order to achieve the above object, the present invention adopts following technical scheme to solve:

A method for preparing sebacic acid by cracking castor oil compounds, characterized in that, according to the following steps:

The castor oil compound is saponified and acidified to obtain ricinoleic acid, and the lye with a mass fraction of 40-50%, a loaded catalyst and a diluent are added to the ricinoleic acid to carry out a cracking reaction; the reaction temperature is 250-320°C, The reaction time is 3~6h; the volume of lye: the volume of castor oil compound=1~3:1; the amount of loaded iron catalyst is 5~10% of the mass of castor oil compound; the volume of diluent: castor oil compound Volume=2～6:1;

After the reaction, the reaction solution is filtered, the filtrate is adjusted to pH = 6 with 3-6 mol/l hydrochloric acid or sulfuric acid, the solution is layered, the water phase is taken, and 3-6 mol/l hydrochloric acid or sulfuric acid is added thereto to adjust the pH = 2 to obtain sebacic acid.

Further, the lye is NaOH solution or KOH solution.

Further, the castor oil compound is one or a mixture of castor oil, ricinoleic acid, ricinoleate and ricinoleate.

It should be noted that: ricinoleic acid esters are methyl ricinoleate and ethyl ricinoleate; ricinoleic acid salts are sodium ricinoleate and potassium ricinoleate.

Further, the diluent adopts liquid paraffin.

Further, the preparation method of described supported catalyst is carried out as follows:

(1) Pretreatment of the carrier: Activated carbon 10-300 mesh (i.e., particle size 2000-50 microns), soaked in ethanol and deionized water for 4-12 hours, then washed with deionized water for 3-5 times, at 80-110℃ Dry in an oven for 8-12 hours; treat with HNO ₃ with a mass fraction of 5-15% at 80°C for 4-8 hours, wash with water until neutral, and dry in an oven at 80-110°C for 8-12 hours to obtain a pretreated carrier.

(2) Impregnation and precipitation: impregnate the carrier with soluble iron salt for 2 to 4 hours, then add NaOH solution or KOH solution with a concentration of 0.05 to 0.3mol/l dropwise, stir for 0.5 to 1 hour, and put it in a constant temperature water bath at 80 to 90°C React in medium for 0.5~9h, adjust pH=8~11; volume of carrier: volume of soluble iron salt=1:5~10.

(3) Post-precipitation treatment: filter the activated carbon, wash it with dilute lye, and then place it in a drying oven at 110°C for 10-12 hours to obtain a catalyst precursor. Under treatment for 3 to 6 hours, a supported catalyst is obtained.

Further, the activated carbon in step (1) is shell charcoal, coal-based charcoal or wood charcoal.

Further, the specific surface area of the activated carbon in step (1) is 1000-1800m ² /g, the average pore diameter is 0.3-2nm, the pore volume is 0.3-1.2ml/g, and the strength is ≥95%.

Further, the soluble iron salt in step (2) is nitrate, sulfate, hydrochloride, acetate, oxalate.

Further, the iron content in the soluble iron salt in step (2) is 10%-15%.

Advantage and beneficial effect of the present invention are:

(1) The supported catalyst of the present invention is obtained by the impregnation-precipitation method, with activated carbon as the carrier, soluble iron salt as the impregnation solution, and NaOH or KOH as the precipitating agent. The preparation process is simple, and the obtained supported catalyst has a high amount of iron . Since NaOH or KOH is used in the process of preparing sebacic acid by cracking castor oil, using NaOH or KOH as a precipitating agent in the preparation process of the supported catalyst can not only increase the iron loading capacity of the supported catalyst, but also make the supported catalyst The process is in an alkaline environment, which is the same as the alkaline environment in the cleavage reaction, so that the supported catalyst can exist stably in the alkaline environment.

(2) The supported catalyst is used in the reaction of cracking castor oil compounds to produce sebacic acid. The yield of the product obtained is equivalent to that of powdered iron oxide as the catalyst. At the same time, the iron content in the product can be significantly reduced, and the catalyst can recycle and re-use. This process avoids the potential harm to the product caused by the traditional Pb ₃ O ₄ catalyst, and avoids the generation of phenol-containing wastewater.

Below by embodiment the present invention will be further elaborated.

Detailed ways

Embodiment 1 (comparative example)

Add 30ml of castor oil into a 500ml three-necked flask, then add 120ml of 3mol/l NaOH solution for saponification, after saponification, adjust pH=6 with 6mol/l HCl, and process to obtain ricinoleic acid. The obtained ricinoleic acid was added to a 500ml three-necked flask, and 120ml of liquid paraffin, 30ml of 40% NaOH, and a powdered iron oxide catalyst of 1% castor oil mass were added to it, and the reaction temperature was 280°C for 5 hours. After the reaction is completed, filter the reaction liquid, adjust the pH=6 with 3-6 mol/l hydrochloric acid or sulfuric acid in the filtrate, separate the solution, take the water phase and add 3-6 mol/l hydrochloric acid or sulfuric acid to it to adjust the pH=2 to obtain sebacic acid . The content of sebacic acid was determined by thin-layer chromatography, the yield of sebacic acid was calculated, and the iron content in the crude product was determined by spectrophotometry. The specific results are shown in Table 1. The catalyst is reused to obtain the yield of sebacic acid and the iron content in the crude product.

Example 2

Grind the shell activated carbon to 40-60 meshes, soak it in ethanol and deionized water for 8 hours, wash it three times, and dry it in an oven at 110°C for 8 hours. After drying, it was treated with 15% _HNO3 at 80 °C for 6 h, washed with water until neutral, and dried in an oven at 80 °C for 8 h to obtain nitric acid-modified shell activated carbon. Weigh 5g of nitric acid modified fruit shell activated carbon, impregnate it with 20ml ferric nitrate with 10% iron content at room temperature for 2h, then add NaOH with a concentration of 0.05mol/l dropwise, stir for 0.5h, and put it in a constant temperature water bath at 90°C After reacting for 6 hours, adjust the pH to 8; filter the activated carbon, wash it successively with 0.10 mol/l NaOH solution, and then place it in a drying oven at 110° C. for 10 hours to obtain a catalyst precursor. The catalyst precursor was calcined in a muffle furnace at 350 °C for 4 h to obtain a shell activated carbon-supported catalyst.

The supported catalyst prepared above is soaked for a period of time with 40%NaOH, then carry out the cracking reaction according to the operation steps of Example 1, wherein the addition of catalyst is 5% of the castor oil quality, and other conditions are the same as Example 1. The content of sebacic acid was determined by thin-layer chromatography, the yield of sebacic acid was calculated, and the iron content in the crude product was determined by spectrophotometry. The specific results are shown in Table 1.

Example 3

The woody activated carbon was crushed to 40-60 mesh, soaked in ethanol and deionized water for 4 hours, washed 5 times, and dried in an oven at 110°C for 8 hours. After drying, it was treated with 10% _HNO3 at 80 °C for 4 h, washed with water until neutral, and dried in an oven at 80 °C for 12 h to obtain nitric acid-modified woody activated carbon. Weigh 5g of nitric acid-modified woody activated carbon, impregnate it with 32ml ferric nitrate with 10% iron content for 4h at room temperature, then add NaOH with a concentration of 0.3mol/l and stir for 1h, put it in a constant temperature water bath at 90°C for 0.5h, and adjust the pH =8. Activated carbon was filtered, washed successively with 0.10 mol/l NaOH, and then placed in a drying oven at 110° C. for 10 h to obtain a catalyst precursor. The catalyst precursor was calcined in a muffle furnace at 350 °C for 6 h to obtain a wood-based activated carbon-supported catalyst.

The catalyst prepared above was soaked for a period of time with 40%NaOH, and then reacted according to the operation steps of Example 1, wherein the addition of the catalyst was 5% of the castor oil quality, and other conditions were the same as in Example 1. The content of sebacic acid was determined by thin-layer chromatography, the yield of sebacic acid was calculated, and the iron content in the crude product was determined by spectrophotometry. The specific results are shown in Table 1.

Example 4

The coal-based activated carbon was crushed to 40-60 meshes, soaked in ethanol and deionized water for 12 hours, washed 5 times, and dried in an oven at 110°C for 12 hours. After drying, it was treated with 5% _HNO3 at 80 °C for 8 h, washed with water until neutral, and dried in an oven at 110 °C for 8 h to obtain nitric acid-modified coal-based activated carbon. Weigh 5g of nitric acid-modified coal-based activated carbon, impregnate it with 40ml of ferric nitrate containing 15% iron for 4 hours at room temperature, then add NaOH with a concentration of 0.3mol/l, stir for 1 hour, put it in a constant temperature water bath at 90°C for 9 hours, adjust pH=11. Activated carbon was filtered, washed successively with 0.10 mol/l NaOH, and then placed in a drying oven at 110° C. for 12 hours to obtain a catalyst precursor. The catalyst precursor was calcined in a muffle furnace at 350 °C for 3 h to obtain a coal-based activated carbon-supported catalyst.

The catalyst prepared above was soaked for a period of time with 40%NaOH, and then reacted according to the operation steps of Example 1, wherein the addition of the catalyst was 5% of the castor oil quality, and other conditions were the same as in Example 1. The content of sebacic acid was determined by thin-layer chromatography, the yield of sebacic acid was calculated, and the iron content in the crude product was determined by spectrophotometry. The specific results are shown in Table 1.

Example 5

The difference between this example and Example 4 is that the catalyst precursor was calcined in a muffle furnace at 400° C. for 4 hours. The castor oil compound is methyl ricinoleate, the catalyst addition is 8% of the castor oil quality, 90ml40% NaOH, 60ml liquid paraffin are added, the reaction temperature is 250°C, and the reaction is 6h. Other conditions are the same as in Example 4, and the obtained The results are shown in Table 1.

Example 6

This embodiment is the same as Example 5, except that the castor oil compound used is sodium ricinoleate, 30ml50% NaOH, 180ml liquid paraffin are added, the reaction temperature is 300°C, and the reaction is 3h. Other conditions are the same as in Example 5. The results obtained are shown in Table 1.

Example 7

The difference between this embodiment and Example 6 is that the lye is KOH, and other conditions are the same as in Example 6. The results obtained are shown in Table 1.

The yield and iron content of sebacic acid under the different embodiments of table 1

Example Sebacic acid yield (%) Iron content (μg/g) Example 1 67.2 820.2 Example 2 66.4 82.8 Example 3 66.0 96.1 Example 4 66.7 87.4 Example 5 62.3 102.4 Example 6 65.8 100.9 Example 7 64.9 101.2

Example 8

The catalyst that embodiment 2 obtains is recovered, and is used in the cracking reaction of castor oil. Catalyst is reacted by the operating procedure of embodiment 1, wherein the add-on of catalyst is 10% of castor oil quality, and catalyst is reused three times. The content of sebacic acid was determined by thin-layer chromatography, the yield of sebacic acid was calculated, and the iron content in the crude product was determined by spectrophotometry. The specific results are shown in Table 2.

The yield and iron content of sebacic acid under different times of repeated use in table 2

Reuse times Sebacic acid yield (%) Iron content (μg/g) 1 64.2 79.8 2 63.7 81.9 3 60.2 76.5

Example 9

The catalyst that embodiment 3 obtains is recovered, and is used in the cracking reaction of castor oil. Catalyst is reacted by the operating procedure of embodiment 1, wherein the add-on of catalyst is 8% of castor oil quality, and catalyst is reused three times. The content of sebacic acid was determined by thin-layer chromatography, the yield of sebacic acid was calculated, and the iron content in the crude product was determined by spectrophotometry. The specific results are shown in Table 3.

The yield and iron content of sebacic acid under different times of repeated use in table 3

Reuse times Sebacic acid yield (%) Iron content (μg/g)

1 63.9 94.3 2 62.5 96.2 3 59.2 95.1

Example 10

The catalyst obtained in Example 4 was recovered and used in the cracking reaction of castor oil. Catalyst is reacted by the operating procedure of embodiment 1, wherein the add-on of catalyst is 10% of castor oil quality, and catalyst is reused three times. The content of sebacic acid was determined by thin-layer chromatography, the yield of sebacic acid was calculated, and the iron content in the crude product was determined by spectrophotometry. The specific results are shown in Table 4.

The yield and iron content of sebacic acid under different times of repeated use in table 4

Reuse times Sebacic acid yield (%) Iron content (μg/g) 1 64.8 78.7 2 63.0 86.9 3 61.4 79.5

Claims (7)

1. a method for preparing sebacic acid by cracking of castor oil compounds, is characterized in that, according to the following steps: Castor oil compounds are saponified and acidified to obtain ricinoleic acid, and lye with a mass fraction of 40-50%, supported catalyst and diluent are added to ricinoleic acid for cracking reaction, and the reaction temperature is 250-320° C, the reaction time is 3~6h; the volume of lye: the volume of castor oil compound=1~3:1; the amount of loaded iron catalyst is 5~10% of the mass of castor oil compound; the volume of diluent: castor oil The volume of the compound is 2~6:1; after the reaction, the reaction solution is filtered, and the filtrate is adjusted to pH=6 with 3~6mol/l hydrochloric acid or sulfuric acid, the solution is layered, and the aqueous phase is taken and 3~6mol/l hydrochloric acid or sulfuric acid is added Sebacic acid is obtained when pH=2 is adjusted; The preparation method of described supported catalyst is carried out as follows: (1) Pretreatment of the carrier: Activated carbon 10-300 mesh, soaked in ethanol and deionized water for 4-12 hours, then washed with deionized water for 3-5 times, dried in an oven at 80-110°C for 8-12 hours; The mass fraction is 5-15% HNO ₃ is treated at 80°C for 4-8h, washed with water until neutral, and dried in an oven at 80-110°C for 8-12h to obtain a pretreated carrier; (2) Impregnation and precipitation: impregnate the carrier with soluble iron salt for 2~4h, then add NaOH solution or KOH solution with a concentration of 0.05~0.3mol/l dropwise, stir for 0.5~1h, and put it in a constant temperature of 80~90°C React in water bath for 0.5~9h, adjust pH=8~11; volume of carrier: volume of soluble iron salt=1:5~10; (3) Post-precipitation treatment: filter the activated carbon, wash it with dilute lye, and then place it in a drying oven at 110°C for 10-12 hours to obtain a catalyst precursor. Treat under C condition 3～6h, obtain supported catalyst; The castor oil compound is one or a mixture of castor oil, ricinoleic acid, ricinoleate and ricinoleate. 2. The method for preparing sebacic acid by pyrolysis of castor oil compounds as claimed in claim 1, characterized in that, the lye is NaOH solution or KOH solution. 3. The method for preparing sebacic acid by cracking castor oil compounds as claimed in claim 1, wherein said diluent adopts liquid paraffin. 4. The method for preparing sebacic acid by cracking castor oil compounds according to claim 1, characterized in that the activated carbon in the step (1) is fruit shell charcoal, coal-based charcoal or wood charcoal. 5. The method for preparing sebacic acid by pyrolysis of castor oil compounds as claimed in claim 1, characterized in that, the specific surface area of the activated carbon in the step (1) is 1000~ ^1800m2 /g, and the average pore diameter is 0.3~2nm , the pore volume is 0.3~1.2ml/g, and the strength is ≥95%. 6. the method for preparing sebacic acid by cracking castor oil compounds as claimed in claim 1, is characterized in that, the soluble iron salt described in the step (2) is nitrate, sulfate, hydrochloride, acetic acid Salt, oxalate. 7. The method for preparing sebacic acid by cracking castor oil compounds as claimed in claim 1, wherein the iron content in the soluble iron salt in the step (2) is 10% to 15%.