CN101092353A - Preparation method for transforming animal and vegetable oil and fat to mono ester fatty acid - Google Patents

Abstract

The invention relates to a method for preparing fatty acid monoesters converted from animal and vegetable oils that can be fully recycled without waste discharge in the technical field of bioenergy. The invention comprises: pumping animal and vegetable oil raw materials, monohydric alcohol raw materials and catalysts into a pressure-resistant reaction tank; sealing the pressure-resistant reaction tank, stirring and mixing, heating to the transesterification reaction temperature, and keeping the temperature until the transesterification reaction is completed; The transesterification reaction mixture is directly sprayed into the evaporator from the pressure-resistant reaction tank, and the excess raw material alcohol and catalyst volatilize into steam, which is introduced into the condenser to condense into liquid and recycled; after the alcohol and catalyst are completely volatilized, the remaining mother liquor is separated and has a light specific gravity The lower layer is fatty acid monoester, and the higher specific layer is glycerol by-product. The invention has wide sources of raw materials, easy catalyst recycling, mild production conditions, short reaction time and simple process, and is suitable for large-scale industrial production.

Description

Method for preparing fatty acid monoester converted from animal and vegetable oil

technical field

The invention relates to a method for producing biodiesel in the technical field of bioenergy, in particular to a method for preparing fatty acid monoesters converted from animal and vegetable oils without waste discharge and fully recyclable.

Background technique

Biodiesel refers to fatty acid methyl esters produced by transesterification with methanol or ethanol using renewable animal and vegetable oils (such as rapeseed oil, soybean oil, peanut oil, palm oil, coconut oil, recycled cooking oil, animal fat, etc.) or ethyl ester. Such fatty acid methyl or ethyl esters have similar properties to fossil-derived diesel and can be used as diesel. Production of diesel from this renewable resource is one of the solutions to the fossil energy shortage crisis. At the same time, due to the environmental pollution caused by waste cooking oil flowing into rivers and seas through sewers every year, burning used vegetable oil and animal oil in restaurants or households to produce biodiesel can reduce the pressure on environmental pollution and provide vehicle fuel for economic development. , has important social and economic significance.

At present, the key step in the production of biodiesel is the transesterification reaction. The alkali-catalyzed reaction is seriously affected by the free fatty acid and moisture content in the raw material; conventional sulfuric acid, hydrochloric acid and sulfonic acid catalyzed reaction temperature and pressure are high, and the reaction rate is slow. The common disadvantages of the above two methods are that waste liquid is discharged after catalytic neutralization to pollute the environment, and the subsequent refining process of the product is complicated. The biocatalytic method has mild reaction conditions, but the cost of the enzyme is high, the service life is short, the catalytic process is long, and large-scale production is difficult. The supercritical alcohol transesterification method does not require a catalyst, the time is very short, and the conversion rate is high. The disadvantage is that the reaction needs to be carried out under high temperature and high pressure, which requires high equipment performance, large investment, and large energy consumption.

After searching the existing technical literature, it was found that Zhang Hairong et al. published "Study on the Synthesis of Biodiesel from Esterification and Acidification Oil Catalyzed by Solid Acid"("Petroleum and Natural Gas Chemical Industry", 2007, Vol. 36, No. 2, pp. 114-117) papers. This paper utilizes the modified SO ₄ ^2- -TiO ₂ /clay solid acid catalyst to catalyze the ester conversion reaction in biodiesel synthesis. The reaction temperature is 70°C, the mass ratio of alcohol to oil is 0.43:1, the catalyst dosage is 5% of the feedstock oil dosage, the reaction time is 6-8 hours, the conversion rate of swill oil reaction for 6 hours is 90-97%, and the refined fatty acid reaction time is 8 hours The conversion rate is 95-98%. The modified SO ₄ ^2- -TiO ₂ /clay solid acid catalyst can be recycled 20 times. Compared with concentrated sulfuric acid and strong acid resin, the homogeneous catalyst sodium methoxide has the advantages of high catalytic activity, no saponification, less catalyst consumption than strong acid resin, good stability, and refined fatty acid reaction when it is used for 20 times. The conversion rate at 8 hours can still reach more than 90%. However, the catalytic reaction time of solid catalyst is too long, the catalyst is easily poisoned, and waste solid catalyst is still a source of pollution. At the same time, the production capacity of the equipment is low. Therefore, it is necessary to develop a production process with high production efficiency, large equipment production capacity and no waste discharge.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies and defects of the prior art, and provide a method for preparing fatty acid monoesters converted from animal and vegetable oils. In the production of biodiesel, the invention catalyzes the conversion of animal and vegetable oils to prepare fatty acid monoesters, which is a green production method with no waste discharge, high efficiency and environment friendliness, and can produce biodiesel in large quantities in a fast, simple, low-cost manner.

The present invention is achieved through the following technical solutions, and the present invention specifically comprises the following steps:

(1) The animal and vegetable oil raw material of required quantity, monohydric alcohol raw material and the catalyst of required quantity are transported in the pressure-resistant reaction tank with pump;

(2) Seal the pressure-resistant reaction tank, stir and mix, after heating to the required temperature for the transesterification reaction, keep the temperature until the transesterification reaction is completed;

(3) The transesterification reaction mixture is directly sprayed into the evaporator from the pressure-resistant reaction tank, and excessive raw material alcohol and catalyst are volatilized into steam, introduced into the condenser to condense into liquid, and recycled;

(4) After the alcohol and the catalyst are completely volatilized, the remaining mother liquor is separated into layers. The layer with light specific gravity is fatty acid monoester, that is, the obtained biodiesel, and the layer with high specific gravity is glycerol by-product.

In step (1), the animal and vegetable oil raw material is vegetable oil, animal oil or a mixture thereof;

Described vegetable oil comprises fatty acid triglycerides extracted from plant seeds, pulp and other parts (such as plant roots, stems, leaves), such as soybean oil, rapeseed oil, palm oil, cottonseed oil, jatropha fruit Oil, Microalgae Oil, Peanut Oil, Sunflower Oil, Castor Oil, Sesame Oil, Linseed Oil, Safflower Oil, Tea Seed Oil, Olive Oil, Palm Kernel Oil, Corn Oil, Oil Coconut Oil, Carnation Oil, Udonia Cypress seed oil, tallow fruit oil, tung oil, sumac fruit oil, hazelnut oil, euonymus fruit oil, euphorbia fruit oil, perilla fruit oil, eucalyptus fruit oil, pistachio fruit oil, leprosy Any one of tree fruit oil, tung oil, camellia oleifera fruit oil, etc. or any mixture thereof.

The raw material of the fatty acid triglycerides can be cooking waste oil or waste oil recovered from gutters.

The animal and vegetable fats and oils, wherein the animal fats include fatty acid triglycerides extracted from animal body, such as chicken fat, duck fat, lard fat, beef fat, suet fat, turkey fat, etc. or any mixture thereof.

In step (1), the catalyst is trifluoroacetic acid; the catalyst concentration used is 0.1mol/L-3.0mol/L.

In step (1), the alcohol includes monohydric alcohols with 1-8 carbons, such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol and octanol, and isomers thereof.

The alcohol is added in an amount of alcohol:fat molar ratio=1:1 to 60:1.

In step (2), the temperature of the transesterification reaction is 80°C to 200°C;

Said reaction time is 0.1 to 5 hours.

Compared with the prior art, the present invention has wide sources of raw materials, easy catalyst recycling, mild production conditions, short reaction time and simple process, and is suitable for large-scale industrial production. At the same time, the total conversion rate of the present invention into monoesters is high, and the total conversion rate of some parts is as high as 98-100%. The excess alcohol and catalyst can be fully recycled through simple evaporation, and the by-product glycerin is passed through simple phase separation or product through simple distillation. Can be refined.

Detailed ways

The embodiments of the present invention are described in detail below: the present embodiment is implemented under the premise of the technical solution of the present invention, and detailed implementation and specific operation process are provided, but the protection scope of the present invention is not limited to the following implementation example. Those skilled in the art make various changes or modifications to the present invention, such as starting triglyceride raw materials can be replaced by peanut oil, sunflower oil, castor oil, sesame oil, linseed oil, safflower oil, tea seed oil, olive oil, Palm kernel oil, corn oil, oil coconut oil, sorbetia oil, uber oil, tung oil, anacardiaceae seed oil, hazelaceae seed oil, euonymus seed oil, euphorbiaceae seed oil, perilla seed oil and duck Grease, tallow, suet, turkey fat, etc. Alcohols can be replaced by, butanol, pentanol, hexanol, heptanol and octanol, and alcohols in their isomer forms, these equivalent forms also fall within the scope of the invention scope of protection.

Example 1

Take 1ml of soybean oil, 0.20ml of methanol, and 0.28ml of trifluoroacetic acid, so that the molar ratio of alcohol to oil is 5:1, and the concentration of trifluoroacetic acid is 2.5M, put them into a stainless steel tube, heat to 180°C in airtight, and keep warm for 0.5 hours. Then open the stainless steel tube so that the mixture is sprayed into a round-bottomed glass flask, and the unreacted methanol and trifluoroacetic acid catalyst evaporate, condense and collect for full recycling; the non-volatile part is cooled and divided into upper and lower layers, and the upper layer is biodiesel. The lower layer is glycerol. The biodiesel in the upper layer was analyzed by gas chromatography-mass spectrometry, and the fatty acid methyl ester content was 94%.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 2

Take 1ml of rapeseed oil, 0.6ml of ethanol, and 0.33ml of trifluoroacetic acid, so that the molar ratio of alcohol to oil is 11:1, and the concentration of trifluoroacetic acid is 2.2M, add them into a closed stainless steel tube and heat to 120°C, and keep warm for 5 hours. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The measured density of the upper layer is 0.900, and the content of fatty acid methyl ester is 97% according to gas chromatography-mass spectrometry analysis.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 3

Take 1ml of palm oil, 1.3ml of propanol, and 0.23ml of trifluoroacetic acid, so that the molar ratio of alcohol to oil is 18:1, and the concentration of trifluoroacetic acid is 2.2M, add them into a closed stainless steel tube and heat to 150°C, and keep warm for 0.1 hour. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The measured density of the upper layer is 0.878.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 4

Take 1ml of cottonseed oil, 0.9ml of butanol, and 0.10ml of trifluoroacetic acid, so that the molar ratio of alcohol to oil is 10:1, and the concentration of trifluoroacetic acid is 0.7M, add them into a closed stainless steel tube and heat to 130°C, and keep warm for 0.6 hours. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The measured density of the upper layer was 0.860, and analyzed by gas chromatography-mass spectrometry, wherein the content of fatty acid methyl ester was 99.96%.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 5

Take 1ml of jatropha oil, 0.13ml of amyl alcohol, and 0.1ml of trifluoroacetic acid, so that the molar ratio of alcohol to oil is 1:1, and the concentration of trifluoroacetic acid is 0.11M, add them into a stainless steel tube, heat to 100°C in airtight, and keep warm for 2 hours. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The density of the upper layer is 0.862, and the content of fatty acid methyl ester is 97% by gas chromatography-mass spectrometry analysis.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 6

Take 0.5ml of microalgae oil, 0.37ml of ethanol, and 0.05ml of trifluoroacetic acid so that the molar ratio of alcohol to oil is 6:1, and the concentration of trifluoroacetic acid is 0.7M, add them into a closed stainless steel tube and heat to 200°C, and keep warm for 0.25 hours. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The measured density of the upper layer is 0.876, and the content of fatty acid methyl ester is 99% according to gas chromatography-mass spectrometry analysis.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 7

Take uber oil 0.5ml, heptanol 0.43ml, trifluoroacetic acid 0.01ml, so that the molar ratio of alcohol to oil is 6:1, and the concentration of trifluoroacetic acid is 0.1M, put them into a stainless steel tube, seal and heat to 190°C, and keep warm for 1 hour. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The upper product was analyzed by gas chromatography-mass spectrometry, and the fatty acid methyl ester content was 83%.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 8

Take 1ml of tung oil, 0.2ml of octanol, and 0.35ml of trifluoroacetic acid, so that the molar ratio of alcohol to oil is 1:1, and the concentration of trifluoroacetic acid is 3.0M, put them into a stainless steel tube, heat to 80°C in airtight, and keep warm for 0.4 hours. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The upper product was analyzed by gas chromatography-mass spectrometry, and the fatty acid methyl ester content was 98%.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 9

Take 1ml of chicken fat, 0.4ml of methanol, and 0.2ml of trifluoroacetic acid, so that the molar ratio of alcohol to oil is 10:1, and the concentration of trifluoroacetic acid is 1.6M, put them into a stainless steel tube, heat to 160°C in airtight, and keep warm for 0.8 hours. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The upper product was analyzed by gas chromatography-mass spectrometry, and the fatty acid methyl ester content was 100%.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 10

Take 0.5ml of waste vegetable oil, 0.98ml of methanol, and 0.44ml of trifluoroacetic acid, so that the molar ratio of alcohol to oil is 41:1, and the concentration of trifluoroacetic acid is 2.5M, put them into a stainless steel tube, heat to 180°C in airtight, and keep warm for 2 hours. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The measured density of the upper layer is 0.884.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Example 11

Take 0.5ml of lard, 1.16ml of methanol, and 0.43ml of trifluoroacetic acid, so that the molar ratio of alcohol to oil is 60:1, and the concentration of trifluoroacetic acid is 2.7M, put them into a stainless steel tube, heat to 165°C in airtight, and keep warm for 4 hours. Then open the stainless steel tube to spray the mixture into a round bottom glass flask, evaporate the unreacted methanol and trifluoroacetic acid, collect and reuse after condensation; the non-volatile part is divided into upper and lower layers after cooling, the upper layer is biodiesel, and the lower layer is glycerin . The measured density of the upper layer is 0.830.

In this embodiment, the total conversion rate into monoesters is high, as high as 98-100%, and the by-product glycerin can be refined through simple phase separation or simple distillation of the product. The catalyst in this embodiment can be fully recycled, has no waste discharge, and is suitable for environmentally friendly industrial production. Compared with the prior art, the transesterification reaction time in this embodiment can be reduced from 6 to 8 hours to 0.1 hour.

Claims (10)

1. a kind of preparation method of animal and vegetable oil conversion fatty acid monoester is characterized in that, specifically comprises the steps: (1) The animal and vegetable oil raw materials, the monohydric alcohol raw materials and the catalyst are pumped into the pressure-resistant reaction tank; (2) Seal the pressure-resistant reaction tank, stir and mix, after heating to the transesterification reaction temperature, keep the temperature until the transesterification reaction is completed; (3) The transesterification reaction mixture is directly sprayed into the evaporator from the pressure-resistant reaction tank, and excessive raw material alcohol and catalyst are volatilized into steam, introduced into the condenser to condense into liquid, and recycled; (4) After the alcohol and the catalyst are completely volatilized, the remaining mother liquor is layered. The layer with light specific gravity is fatty acid monoester, and the layer with heavy specific gravity is glycerol by-product. 2. the preparation method of animal and vegetable fat conversion fatty acid monoester as claimed in claim 1, is characterized in that, in step (1), described animal and vegetable fat raw material is vegetable fat, animal fat or its mixture. 3. the preparation method of animal and vegetable fat conversion fatty acid monoester as claimed in claim 1, is characterized in that, described animal and vegetable fat, wherein vegetable fat refers to: fatty acid triglyceride, is specifically: soybean oil, vegetable oil Seed Oil, Palm Oil, Cottonseed Oil, Jatropha Oil, Microalgae Oil, Peanut Oil, Sunflower Oil, Castor Oil, Sesame Oil, Linseed Oil, Safflower Oil, Tea Seed Oil, Olive Oil, Palm Kernel Oil, Corn oil, oil coconut oil, sorbet oil, black cypress seed oil, tallow oil, tung oil, sumac oil, hazelnut oil, euonymus oil, euphorbia oil, perilla oil, Any one of eucalyptus fruit oil, pistachio fruit oil, jatropha fruit oil, tung tree fruit oil, camellia oleifera fruit oil or any mixture thereof. 4. the preparation method of animal and vegetable fat conversion fatty acid monoester as claimed in claim 1, is characterized in that, described animal and vegetable fat, wherein animal fat refers to: fatty acid triglyceride, is specifically: chicken fat, duck fat Fat, lard, tallow, suet, turkey fat or any combination thereof. 5. the preparation method of animal and vegetable oil conversion fatty acid monoester as claimed in claim 1, is characterized in that, in step (1), described catalyzer is trifluoroacetic acid. 6. The method for preparing fatty acid monoesters converted from animal and vegetable oils as claimed in claim 1 or 5, characterized in that the concentration of the catalyst is 0.1mol/L-3.0mol/L. 7. the preparation method of animal and vegetable oil conversion fatty acid monoester as claimed in claim 1 is characterized in that, in step (1), described alcohol is the monohydric alcohol of 1-8 carbon, is specifically: methyl alcohol, ethanol , propanol, butanol, pentanol, hexanol, heptanol and octanol and any of its isomers. 8. The method for preparing fatty acid monoesters converted from animal and vegetable oils as claimed in claim 1 or 7, characterized in that the amount of the alcohol added is alcohol: oil molar ratio=1:1 to 60:1. 9. The method for preparing fatty acid monoesters converted from animal and vegetable oils as claimed in claim 1, characterized in that, in step (2), the temperature of the transesterification reaction is 80°C to 200°C. 10. The method for preparing fatty acid monoesters converted from animal and vegetable oils as claimed in claim 1 or 9, characterized in that the reaction time of the transesterification reaction is 0.1 to 5 hours.