CN119143597A

CN119143597A - Method for separating oleic acid from byproducts of OPO grease and oleic acid

Info

Publication number: CN119143597A
Application number: CN202411612145.7A
Authority: CN
Inventors: 钟凯; 王文祥; 徐坤华; 史立文; 许荣年
Original assignee: Zanyu Technology Group Co ltd
Current assignee: Zanyu Technology Group Co ltd
Priority date: 2024-11-13
Filing date: 2024-11-13
Publication date: 2024-12-17

Abstract

The present disclosure provides a method for separating oleic acid from byproducts of OPO grease and oleic acid. The method comprises the steps of (1) taking the mass percentage as a reference, the seed crystal comprises 70-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of glyceryl monostearate or glyceryl monostearate and distearate, (2) adding the seed crystal into OPO byproducts according to the addition amount of 10-50 wt%, under the protection of N ₂, stirring at the temperature of 70 ℃, obtaining crystal slurry, (3) pumping the crystal slurry into a crystallization kettle, protecting and stirring the crystal slurry by N ₂, setting the initial temperature of the crystallization kettle to 70 ℃, preserving the temperature for 1h, cooling the temperature from 70 ℃ to 55 ℃ by 3-5 ℃ per hour, cooling the temperature from 55 ℃ to 20 ℃ by 2-3 ℃ per hour, cooling the temperature from 20 ℃ to 15-8 ℃ by 1-2 ℃ per hour, preserving the temperature for at least 5h, and obtaining a filter cake and filtrate by pressure filtration under the pressure of 0.6 MPa. The method of the application uses OPO byproducts as raw materials to recover high-quality oleic acid, the oleic acid purity is more than 80%, and the recovery rate is more than 60%.

Description

Method for separating oleic acid from byproducts of OPO grease and oleic acid

Technical Field

The disclosure relates to the technical field of OPO byproduct separation, in particular to a method for separating oleic acid from OPO grease byproducts and oleic acid.

Background

A method for separating fatty acid from animal fat by temp crystallizing method is disclosed in China patent application (CN 115960678A), and includes such steps as freezing animal fat at low temp to transform liquid animal fat into solid state, heating to be molten, filtering while it is hot, collecting liquid fat, adding aqueous solution containing ascorbyl glucoside and electrolyte, stirring, cooling, crystallizing, solid-liquid separation, and collecting solid fat and liquid fat. The patent application adopts a temperature crystallization method to separate fatty acid in grease, can only be used in animal grease, and has simpler preparation method, but is not applicable to OPO byproduct systems.

For example, chinese patent application (CN 109832351B) provides a fat crystallization promoter and a fat composition thereof, wherein the stearic acid content of the promoter is more than or equal to 40%, and in the triglyceride composition of the promoter, palm stearate (PPP) is less than or equal to 20%, and tristearin triglyceride (StStSt) is more than or equal to 10%. CN 115053931B provides a fat crystallization accelerator, the components include 50-70% of glycerol mono oleic dipalmitate, 10-20% of distearic acid diglyceride, 15-30% of dioleate diglyceride, and the total is 100%. The crystallization promoter can induce fat crystallization, accelerate formation of fat crystallization, improve crystal size, optimize structure and texture of crystallization network, inhibit sand and post hardening of product, and is applied to oil-containing food such as margarine and shortening, but is not applicable to OPO distillation byproduct system, and acetone, petroleum ether and diethyl ether organic solvent are used in preparation of the crystallization promoter.

The Chinese patent application (CN 102408324A) provides a high-purity oleic acid purification process, which takes hydrolyzed palm oil fatty acid as a raw material, prepares high-purity oleic acid by crystallization and filtration after a dry fractionation process, and prepares oleic acid C18:1 with the content of 70 percent.

The Chinese patent application (CN 110194716A) provides a method for preparing high-purity oleic acid, which takes mixed fatty acid as a raw material, and dissolves the mixed fatty acid in an organic solvent to obtain a mixed solution, wherein the organic solvent is one or more of alcohol solvents, ketone solvents, alkane solvents and ester solvents. Oleic acid is obtained by stirring, heat preserving, crystallizing and pressure filtration separation processes, but the purity of the prepared oleic acid is not specifically described.

The technical requirements of separating and recycling high-quality oleic acid from OPO rectification byproducts cannot be met by the literature data reported in the publication, and the separation and recycling research of the OPO rectification byproducts is not reported at present because the OPO rectification byproducts are derived from a specific process and have special components.

Through the comparison and analysis of the prior art, the following technical problems exist in separating and recovering high-quality oleic acid by taking OPO rectification byproducts as raw materials, specifically:

1. The byproducts of OPO grease comprise more complex components, wherein the main components comprise oleic acid, linoleic acid, linolenic acid, stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid glyceride, palmitic acid glyceride, stearic acid glyceride and ester exchange products thereof, the conventional oleic acid separation and recovery process is not suitable for OPO production systems, and the oleic acid separation and recovery process aiming at OPO refining byproducts is yet to be developed.

2. The conventional crystallization process is adopted to treat OPO refining byproducts, the expected level of the crystal formation quantity, the size, the polymorphism type and the final crystal distribution cannot be reached, the crystal morphology is poor, and the oleic acid purity is low.

3. The adoption of the process of adding an organic solvent or high temperature can easily lead to the reduction of the safety of oleic acid, and cannot meet the production requirement of OPO.

4. The filter cake remained after filter pressing can not be reused for a plurality of times.

5. The starting materials for the process should be available commercially.

Disclosure of Invention

The present disclosure provides a method for separating oleic acid from byproducts of OPO grease and oleic acid to address at least one of the technical problems in the prior art.

According to a first aspect of the present disclosure there is provided a method of separating oleic acid from byproducts of OPO grease comprising the steps of:

(1) Preparing seed crystals, wherein the seed crystals comprise 80-100 wt% of stearic acid and 0-20wt% of palmitic acid triglyceride by mass percent;

or the seed crystal comprises 85-100 wt% of stearic acid and 0-15 wt% of glyceryl monostearate;

or the seed crystal comprises 70-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of glyceryl monostearate;

Or the seed crystal comprises 70-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of glyceryl monostearate and distearate;

(2) Preparing crystal slurry:

Adding the seed crystal into OPO byproducts according to the addition amount of 10-50wt%, and stirring at the temperature of 70 ℃ under the protection of N ₂ to obtain crystal slurry;

(3) Crystallization and filter pressing of crystal slurry:

Pumping the crystal slurry into a crystallization kettle, stirring under the protection of N ₂, setting the initial temperature of the crystallization kettle to be 70 ℃, and preserving heat for 1h;

then cooling the temperature from 70 ℃ to 55 ℃ at a cooling rate of 3-5 ℃ per hour;

Then cooling the temperature from 55 ℃ to 20 ℃ at a cooling rate of 2-3 ℃ per hour;

Finally, cooling the temperature from 20 ℃ to 15-8 ℃ at a cooling rate of 1-2 ℃ per hour, and then preserving heat for at least 5 hours to obtain a crystal;

And (3) carrying out filter pressing on the crystal under the conditions of the pressure of 0.6MPa and the temperature of 8-15 ℃ to obtain a filter cake and filtrate, and collecting the filtrate to obtain oleic acid, wherein the filter cake is collected for later use.

In an embodiment, in the step (1), the seed crystal includes 85-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride, and 0-15 wt% of glyceryl monostearate;

Or the seed crystal comprises 85-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of glyceryl monostearate and distearate.

In one embodiment, in the step (1), the seed crystal comprises 85wt% of stearic acid, 10wt% of palmitic acid triglyceride and 5wt% of glyceryl monostearate;

or the seed crystal comprises 85wt% of stearic acid, 10wt% of palmitic acid triglyceride and 5wt% of glyceryl monostearate and distearate.

In one embodiment, in the step (2), the prepared crystal slurry meets the following requirements of, by mass, 25-50wt% of saturated fatty acid, 50-75wt% of unsaturated fatty acid, and 0-5wt% of ester and impurities.

In one embodiment, in the step (2), the stirring speed is at least 200r/min, and the stirring time is at least 30min.

In an embodiment, in the step (3), the stirring speed of the crystallization kettle is 10-50 r/min.

In one embodiment, in the step (3), the temperature is first reduced from 70 ℃ to 55 ℃ at a temperature reduction rate of 5 ℃ per hour;

then cooling the temperature from 55 ℃ to 20 ℃ at a cooling rate of 3 ℃ per hour;

And finally, cooling the temperature from 20 ℃ to 15-8 ℃ at a cooling rate of 2 ℃ per hour, and preserving heat for at least 5 hours to obtain a crystal.

In one embodiment, the method of the present application further comprises the steps of:

(4) Melting the filter cake at 70 ℃ and selectively adding stearic acid, palmitic acid triglyceride, glyceryl monostearate and glyceryl distearate according to the composition of the filter cake to prepare secondary seed crystals, and then adding the secondary seed crystals into OPO byproducts according to the addition amount of 10-50wt%;

Wherein the secondary seed crystal comprises 80-100 wt% of stearic acid and 0-20 wt% of palmitic acid triglyceride;

or the secondary seed crystal comprises 85-100 wt% of stearic acid and 0-15 wt% of glyceryl monostearate;

Or the secondary seed crystal comprises 70-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of glyceryl monostearate;

Or the secondary seed crystal comprises 70-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of mono-distearate glyceride;

(5) Pumping the secondary crystal slurry into a crystallization kettle, charging nitrogen for protection, stirring, setting the initial temperature of the crystallization kettle to be 70 ℃, and preserving heat for 1h;

The crystallization is subjected to filter pressing under the conditions of the pressure of 0.6MPa and the temperature of 8-15 ℃ to obtain a filter cake and filtrate, the filtrate is collected to obtain oleic acid, and the filter cake is collected for later use;

And (5) repeating the steps (4) - (5) for a plurality of times.

In one embodiment, in the step (4), the secondary crystal slurry satisfies the following requirements, by mass, 25-50wt% of saturated fatty acid, 50-75wt% of unsaturated fatty acid, and 0-5wt% of ester and impurities.

According to a second aspect of the present disclosure there is provided oleic acid, obtainable by a process as described in any one of the preceding claims.

Compared with the prior art, the method has the advantages that 1) in the method, substances outside the OPO system are not added additionally, and raw materials or intermediate products contained in the system are used as seed crystals, so that the solvent residue in the oleic acid is not detected (the quantitative limit is 10 mg/kg), and the content of insoluble impurities is less than or equal to 0.05%. 2) In the method, low-temperature control and high-precision gradient temperature control are adopted during crystallization, so that the freshness and safety of the grease can be greatly ensured for the grease, the problems caused by the traditional high-temperature extraction are avoided, and the product is safer. 3) The method is completely suitable for OPO production systems, and can separate and recover high-quality oleic acid by taking OPO refining byproducts as raw materials, wherein the oleic acid purity is more than 80%, and the recovery rate is more than 60%. 4) In order to improve the safety of oleic acid, the method of the application does not add an organic solvent, does not adopt a high-temperature process (the process temperature is not higher than 70 ℃), does not introduce other substances outside an OPO production system, and the prepared oleic acid has undetected solvent residues (the quantitative limit is 10 mg/kg), insoluble impurity content less than or equal to 0.05% and peroxide value less than or equal to 1.0 mmol/kg. 5) In the method, the filter cake remained in filter pressing can be recycled for 5 times at most, and OPO byproducts are utilized to the greatest extent. In the application, the components of the seed crystal all meet the food safety requirement and are from the market, the acquisition channel is convenient, and the industrial application is easy.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become apparent from the following specification.

Drawings

The above, as well as additional purposes, features, and advantages of exemplary embodiments of the present disclosure will become readily apparent from the following detailed description when read in conjunction with the accompanying drawings. Several embodiments of the present disclosure are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which:

in the drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

FIG. 1 shows a gas chromatogram of an untreated OPO byproduct of the disclosure;

FIG. 2 shows a filtrate gas chromatogram obtained in example 1 of the present disclosure;

FIG. 3 shows a filtrate gas chromatogram obtained in example 2 of the present disclosure;

FIG. 4 shows a filtrate gas chromatogram obtained in example 3 of the present disclosure;

fig. 5 shows a filtrate gas chromatogram obtained in example 4 of the present disclosure;

FIG. 6 shows a filtrate gas chromatogram obtained in example 5 of the present disclosure;

FIG. 7 shows a filtrate gas chromatogram obtained in example 6 of the present disclosure;

Fig. 8 shows a filtrate gas chromatogram obtained in comparative example 1 of the present disclosure;

fig. 9 shows a filtrate gas chromatogram obtained in comparative example 2 of the present disclosure.

Detailed Description

In order to make the objects, features and advantages of the present disclosure more comprehensible, the technical solutions in the embodiments of the present disclosure will be clearly described in conjunction with the accompanying drawings in the embodiments of the present disclosure, and it is apparent that the described embodiments are only some embodiments of the present disclosure, but not all embodiments. Based on the embodiments in this disclosure, all other embodiments that a person skilled in the art would obtain without making any inventive effort are within the scope of protection of this disclosure.

According to one embodiment of the present disclosure, the present invention provides a method for separating oleic acid from a byproduct of OPO grease (OPO byproduct for short), comprising the steps of:

(1) Preparing seed crystal, namely preparing the seed crystal by 80-100 wt% of stearic acid and 0-20 wt% of palmitic acid triglyceride;

(2) Preparing crystal slurry:

adding seed crystal into OPO by-product according to the addition amount of 10-50wt%, and stirring at 70 ℃ under the protection of N ₂ to obtain crystal slurry;

(3) Crystallization and filter pressing of crystal slurry:

and (3) carrying out pressure filtration on the crystal at the pressure of 0.6MPa and the temperature of 8-15 ℃ to obtain a filter cake and filtrate, and collecting the filtrate to obtain oleic acid, wherein the filter cake is collected for later use.

The method of the application separates the oleic acid from byproducts generated by synthesizing OPO grease by using seed crystal and a high-precision gradient temperature control method, thereby obtaining high-content oleic acid, and the oleic acid has no residual solvent and is safe and reliable.

In the method of the application, substances outside the OPO system are not added additionally, and raw materials or intermediate products contained in the system are taken as seed crystals, so that the solvent residue in oleic acid is not detected (the quantitative limit is 10 mg/kg), and the content of insoluble impurities is less than or equal to 0.05 percent. In the method, low-temperature control and high-precision gradient temperature control are adopted during crystallization, so that the freshness and safety of the grease can be greatly ensured for the grease, the problems caused by the traditional high-temperature extraction are avoided, and the product is safer.

The method is completely suitable for OPO production systems, and can separate and recover high-quality oleic acid by taking OPO refining byproducts as raw materials, wherein the oleic acid purity is more than 80%, and the recovery rate is more than 60%. In order to improve the safety of oleic acid, the method of the application does not add an organic solvent, does not adopt a high-temperature process (the process temperature is not higher than 70 ℃), does not introduce other substances outside an OPO production system, and the prepared oleic acid has undetected solvent residues (the quantitative limit is 10 mg/kg), insoluble impurity content less than or equal to 0.05% and peroxide value less than or equal to 1.0 mmol/kg. In the method, the filter cake remained in filter pressing can be recycled for 5 times at most, and OPO byproducts are utilized to the greatest extent. In the application, the components of the seed crystal all meet the food safety requirement and are from the market, the acquisition channel is convenient, and the industrial application is easy.

In the application, the crystal seeds provide rigid crystal nuclei, and the oleic acid is adhered to the rigid crystal nuclei to be favorable for forming plump and fine oleic acid crystals, so that the purity of the oleic acid is improved, and other substances outside an OPO production system are not introduced in principle to be preferential in consideration of the requirement of OPO on food safety.

In the application, stearic acid, palmitic acid triglyceride, glyceryl monostearate and glyceryl monostearate are all from commercial products, wherein the stearic acid is food additive stearic acid (also called octadecanoic acid) which accords with the national standard GB 1886.101, the glyceryl monostearate is food additive distilled glyceryl monostearate which accords with the national standard GB 15612, and the glyceryl monostearate and the glyceryl distearate are food additive glyceryl monostearate and food additive which accord with the national standard GB 1986. The palmitic acid triglyceride is a synthetic raw material derived from OPO and is prepared by processing edible vegetable oil, the melting point is more than or equal to 52 ℃, and the iodine value is less than or equal to 34 g I ₂/100 g.

In the application, in the step (3), the crystal slurry prepared in the step (2) is pumped into a crystallization kettle with stirring, nitrogen is filled for protection, the crystallization kettle adopts high-precision gradient temperature control, the stirring speed is 10-50 r/min, and the temperature control precision is +/-0.1 ℃. After the crystal slurry is pumped into the crystallization kettle, the initial temperature of the crystallization kettle is set to 70 ℃, stirring is started, and the crystal slurry stays for 1h at the initial temperature, so that the crystal slurry is completely melted, and the original crystal form is destroyed. When the temperature is in the range of 70 ℃ to 55 ℃, the actual temperature is higher than the crystallization temperature, no crystal is generated, the system is in a clear and transparent state, rapid cooling is adopted, when the temperature is in the range of 55 ℃ to 20 ℃, the actual temperature gradually approaches the crystallization temperature, crystals start to be produced, the system is in a white and semitransparent state, slow cooling is adopted, when the temperature is in the range of 20 ℃ to one of 15-8 ℃, the crystal is full, the system is in a milky semisolid state, and the whole gradient cooling process needs slow cooling in order to avoid oleic acid crystallization.

In the step (1), the seed crystal comprises 85-100 wt% of stearic acid and 0-15 wt% of glyceryl monostearate;

or the seed crystal comprises 85-100 wt% of stearic acid and 0-15 wt% of glyceryl monostearate and distearate;

or the seed crystal comprises 70-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of mono-distearate glyceride.

Preferably, in the step (1), the seed crystal comprises 85-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of glyceryl monostearate;

Or the seed crystal comprises 85-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of mono-distearate glyceride.

For example, the stearic acid content is 70wt%, 80wt%, 85wt%, 90wt%, 95wt%, 100wt%. The content of the glyceryl monostearate is 0wt%, 5wt%, 10wt% and 15wt%. The content of the glyceryl monostearate and the glyceryl distearate is 0wt%, 5wt%, 10wt% and 15wt%. The content of the palmitic acid triglyceride is 0wt%, 5wt%, 10wt%, 15wt% and 20wt%.

More preferably, in step (1), the seed crystal comprises 85% by weight of stearic acid, 10% by weight of palmitic acid triglyceride, 5% by weight of glyceryl monostearate;

Preferably, in the step (2), the prepared crystal slurry meets the following requirements of, by mass, 25-50wt% of saturated fatty acid, 50-75wt% of unsaturated fatty acid, and 0-5wt% of ester and impurities.

Wherein the saturated fatty acids include stearic acid, palmitic acid, myristic acid and lauric acid. Unsaturated fatty acids include oleic acid, linoleic acid, and linolenic acid. Esters include esters in the OPO byproduct and esters in the seed crystal, specifically, esters of the magma include esters in the raw OPO byproduct, such as, for example, glyceryl oleate, glyceryl palmitate, glyceryl stearate, and esters of the seed crystal, including glyceryl monostearate, glyceryl mono-, di-stearate, and glyceryl palmitate.

According to the application, the mass ratio of the seed crystal to the OPO byproduct is 10-50% to 1. In the components of the prepared crystal slurry, the saturated fatty acid consisting of the sum of the percentages of stearic acid, palmitic acid, myristic acid and lauric acid is limited to 25-50wt%, the unsaturated fatty acid consisting of the sum of the percentages of oleic acid, linoleic acid and linolenic acid is limited to 50-75wt%, and the unsaturated fatty acid consists of ester and other impurities is limited to 0-5 wt%, so that the obtained filtrate, namely oleic acid, is kept at the same standard level after subsequent crystallization and press filtration of the crystal slurry, and the stability of the product is ensured. Before crystallization and press filtration of the crystal slurry, the crystal slurry composition is required to be measured, and if the content of a certain composition in the crystal slurry is not in a required range, corresponding substances are required to be added in an adaptive manner to ensure that the crystal slurry composition meets the requirements, so that after subsequent crystallization and press filtration, products of each batch can be ensured to meet production requirements, and the stability of the products is ensured.

Preferably, in step (2), the stirring rate is at least 200r/min and the stirring time is at least 30min.

Preferably, in the step (3), the stirring speed of the crystallization kettle is 10-50 r/min.

Preferably, in the step (3), the crystallized substance obtained after crystallization is pumped into a membrane filter press, and is subjected to filter pressing under the pressure of 0.6MPa and the temperature of 8-15 ℃, the obtained filtrate is oleic acid, nitrogen is filled for preservation, and the filter cake enriched in the filter bag is collected for later use.

Preferably, in the step (3), the temperature is firstly reduced from 70 ℃ to 55 ℃ at a temperature reduction rate of 5 ℃ per hour;

Further, the method of the application further comprises the steps of:

press-filtering the crystal at the pressure of 0.6MPa and the temperature of 8-15 ℃ to obtain a filter cake and filtrate, collecting the filtrate to obtain oleic acid, and collecting the filter cake for later use;

And (5) repeating the steps (4) - (5) for a plurality of times.

Preferably, in step (3), the main components of the obtained filter cake are saturated fatty acids and esters, and then in step (4), after the filter cake is melted at 70 ℃, the addition amount is calculated according to the fatty acid composition thereof, so as to obtain secondary seed crystals, and the OPO by-product is added again.

Preferably, in the step (4), the secondary crystal slurry meets the following requirements of, by mass, 25-50wt% of saturated fatty acid, 50-75wt% of unsaturated fatty acid, and 0-5wt% of ester and impurities.

According to a second aspect of the present disclosure there is also provided oleic acid, prepared by any one of the methods described above.

In the present application, the gas chromatograph of the by-product produced in the synthesis of OPO grease before the treatment is shown in fig. 1 and table 4, wherein the main components are oleic acid (57.3640%), palmitic acid (26.0434%), stearic acid (6.992%), linoleic acid (9.0856%).

The application will be described in detail with reference to specific examples below:

Example 1

A method for separating oleic acid from byproducts of OPO grease, comprising the steps of:

preparing seed crystal, namely preparing the seed crystal which comprises 100 weight percent of stearic acid by mass percent;

and (2) preparing crystal slurry:

Adding seed crystal into OPO byproduct according to the addition amount of 10wt%, charging N ₂ for protection, stirring at 70 ℃ for 30min at the stirring rate of 200r/min to obtain crystal slurry, wherein the components of the crystal slurry are 25-50wt% of saturated fatty acid, 50-75wt% of unsaturated fatty acid, and less than or equal to 5wt% of ester and other impurities;

And (3) crystallizing and press-filtering the crystal slurry:

pumping the crystal slurry into a crystallization kettle with stirring, filling N ₂ for protection, stirring at a speed of 10r/min, setting the initial temperature of the crystallization kettle to be 70 ℃, and preserving heat for 1h;

Then cooling the temperature from 70 ℃ to 55 ℃ at a cooling rate of 5 ℃ per hour;

Finally, cooling the temperature from 20 ℃ to 15 ℃ at a cooling rate of 2 ℃ per hour, and preserving the temperature at 15 ℃ for 5 hours to obtain a crystal;

And (3) carrying out filter pressing on the crystal at the temperature of 15 ℃ under the pressure of 0.6MPa to obtain a filter cake and filtrate, and collecting the filtrate to obtain oleic acid, wherein the filter cake is collected for later use.

Example 2

The preparation of seed crystal, wherein the seed crystal comprises 95wt% of stearic acid and 5wt% of glyceryl monostearate;

and (2) preparing crystal slurry:

The seed crystal is added into OPO by-product according to the addition amount of 50wt%, and the crystal slurry is obtained by protecting the crystal seed by filling N ₂, stirring the crystal slurry at the temperature of 70 ℃ and the stirring speed of 200r/min for 30min, wherein the components of the crystal slurry are 25-50wt% of saturated fatty acid, 50-75wt% of unsaturated fatty acid, and less than or equal to 5wt% of ester and other impurities.

And (3) crystallizing and press-filtering the crystal slurry:

Pumping the crystal slurry into a crystallization kettle with stirring, filling N ₂ for protection, stirring at a speed of 50r/min, setting the initial temperature of the crystallization kettle to be 70 ℃, and preserving heat for 1h;

Finally, cooling the temperature from 20 ℃ to 8 ℃ at a cooling rate of 2 ℃ per hour, and preserving the temperature at 8 ℃ for 5 hours to obtain a crystal;

And (3) carrying out filter pressing on the crystal under the conditions of the pressure of 0.6MPa and the temperature of 8 ℃ to obtain a filter cake and filtrate, and collecting the filtrate to obtain oleic acid, wherein the filter cake is collected for later use.

Example 3

The preparation of seed crystal, wherein the seed crystal comprises 85wt% of stearic acid and 15wt% of palmitic acid triglyceride by mass percent;

and (2) preparing crystal slurry:

Adding seed crystal into OPO byproduct according to the addition amount of 20wt%, charging N ₂ for protection, stirring at 70 ℃ for 30min at the stirring rate of 200r/min to obtain crystal slurry, wherein the components of the crystal slurry satisfy the conditions of 25-50wt% of saturated fatty acid;

50-75wt% of unsaturated fatty acid;

Esters and other the impurity content is less than or equal to 5wt%.

And (3) crystallizing and press-filtering the crystal slurry:

pumping the crystal slurry into a crystallization kettle with stirring, filling N ₂ for protection, stirring at a speed of 30r/min, setting the initial temperature of the crystallization kettle to be 70 ℃, and preserving heat for 1h;

Finally, cooling the temperature from 20 ℃ to 10 ℃ at a cooling rate of 2 ℃ per hour, and preserving the temperature at 10 ℃ for 5 hours to obtain a crystal;

Example 4

The preparation of seed crystal, wherein the seed crystal comprises 85wt% of stearic acid, 10wt% of palmitic acid triglyceride and 5wt% of glyceryl monostearate;

and (2) preparing crystal slurry:

Adding seed crystal into OPO byproduct according to the addition amount of 30wt%, charging N ₂ for protection, stirring at 70 ℃ for 30min at the stirring rate of 200r/min to obtain crystal slurry, wherein the components of the crystal slurry are 25-50wt% of saturated fatty acid, 50-75wt% of unsaturated fatty acid, and less than or equal to 5wt% of ester and other impurities.

And (3) crystallizing and press-filtering the crystal slurry:

Example 5

The preparation of seed crystal, wherein the seed crystal comprises 85wt% of stearic acid, 10wt% of palmitic acid triglyceride and 5wt% of glyceryl monostearate and distearate;

and (2) preparing crystal slurry:

Adding seed crystal into OPO byproduct according to the adding amount of 40wt%, charging N ₂ for protection, stirring at 70 ℃ for 30min at the stirring rate of 200r/min to obtain crystal slurry, wherein the components of the crystal slurry are 25-50wt% of saturated fatty acid, 50-75wt% of unsaturated fatty acid, and less than or equal to 5wt% of ester and other impurities.

And (3) crystallizing and press-filtering the crystal slurry:

Finally, cooling the temperature from 20 ℃ to 12 ℃ at a cooling rate of 2 ℃ per hour, and preserving the temperature at 12 ℃ for 5 hours to obtain a crystal;

And (3) carrying out filter pressing on the crystal under the conditions of the pressure of 0.6MPa and the temperature of 10 ℃ to obtain a filter cake and filtrate, and collecting the filtrate to obtain oleic acid, wherein the filter cake is collected for later use.

Example 6

This example 6 is substantially the same as example 4 except that in step (3), the temperature is lowered from 70 ℃ to 55 ℃ at a lowering rate of 3 ℃ per hour;

then cooling the temperature from 55 ℃ to 20 ℃ at a cooling rate of 2 ℃ per hour;

finally, the temperature is reduced from 20 ℃ to 8 ℃ at a cooling rate of 2 ℃ per hour, and the temperature is kept at 8 ℃ for 5 hours, so as to obtain a crystal.

Comparative example 1

This comparative example 1 was substantially the same as example 1 except that the seed crystal of step (1) was not disposed.

Comparative example 2

This comparative example 2 is substantially the same as example 4 except that in step (3), the temperature is lowered from 70 ℃ to 40 ℃ at a lowering rate of 5 ℃ per hour;

Then cooling the temperature from 40 ℃ to 8 ℃ at a cooling rate of 3 ℃ per hour, and preserving the temperature at 8 ℃ for 5 hours to obtain the crystal.

Oleic acid prepared in the above examples and comparative examples was tested as follows:

1 oleic acid content and recovery rate obtained in the above examples 1 to 6 and comparative examples 1 to 2 are shown in Table 1:

TABLE 1 oleic acid content and recovery of examples 1-6 and comparative examples 1-2

From the above table 1, it can be seen that when no seed crystal is introduced, even if high-precision gradient cooling is adopted, the obtained oleic acid content and recovery rate are far smaller than those obtained by the common treatment of the seed crystal introduced and the high-precision gradient cooling by the method of the application, and the oleic acid obtained by the method of the application has high purity, the oleic acid content is more than 80%, and the oleic acid recovery rate is more than 60%. This shows that in the present application, by introducing seed crystals, the seed crystals provide rigid nuclei, allowing oleic acid to attach to the rigid nuclei during crystallization, increasing oleic acid recovery and oleic acid content. Therefore, the seed crystal and the high-precision gradient cooling process are not indispensable, and the seed crystal and the high-precision gradient cooling process have a synergistic effect.

In addition, the oleic acid recovery and oleic acid content of comparative example 2 were smaller than those of example 4, in particular, oleic acid recovery was much smaller than that of example 4. This shows that the application adopts 3 cooling gradients, which can provide favorable conditions for crystallization of crystal slurry, and the gradient cooling can improve the recovery rate of crystal slurry.

2, Solvent detection in oleic acid:

Since the process of the present application was carried out without adding any additional substances other than OPO system, the raw materials or intermediate products contained in the system itself were used as seed crystals, and thus the solvent residue in oleic acid was not detected (limit of quantification: 10 mg/kg), and the content of insoluble impurities was not more than 0.05% in examples 1 to 6 described above, and the results are shown in Table 2. In addition, in the application, the crystallization is controlled at low temperature, and the gradient temperature is controlled with high precision, so that the freshness and the safety of the grease can be greatly ensured for the grease, the problems caused by partially adopting the traditional high-temperature extraction are avoided, and the product is safer.

TABLE 2 results of detection of solvent residues in oleic acid of examples 1-6

3, Filter cake repeatability verification:

Taking the filter cake prepared in example 3 as an example, the following repeated cycles were performed:

The method specifically comprises the steps of (4) melting a filter cake at 70 ℃, adding stearic acid and palmitic acid triglyceride according to the components in the filter cake, so as to prepare secondary seed crystals, and then adding the secondary seed crystals into OPO byproducts according to the addition amount of 10-50wt%;

wherein the secondary seed crystal comprises 85wt% of stearic acid and 15wt% of palmitic acid triglyceride;

The secondary crystal slurry comprises 25-50wt% of saturated fatty acid;

50-75wt% of unsaturated fatty acid;

the weight percentage of the ester and the impurity is less than or equal to 5 percent.

Pumping the secondary crystal slurry into a crystallization kettle, filling nitrogen for protection, stirring, setting the initial temperature of the crystallization kettle to be 70 ℃, and preserving heat for 1h;

press-filtering the crystal at the pressure of 0.6MPa and the temperature of 8 ℃ to obtain a filter cake and filtrate, collecting the filtrate to obtain oleic acid, and collecting the filter cake for later use;

and (5) circulating the steps (4) - (5).

And (3) circulating the steps (4) to (5) according to the method for 7 times, wherein the obtained oleic acid content and the obtained oleic acid peroxide value result are shown in table 3:

TABLE 3 oleic acid content and oleic acid peroxide value after each cake recycle

From the above table 3, it can be seen that the oleic acid content obtained in the seventh time of recycling is more than 80%, but the peroxide value of oleic acid starts to rise, which means that the freshness of the oil starts to decrease in the repeated processing process of the oil, and the filter cake is not reused after the fifth time of recycling in order to ensure the safety of oleic acid.

4 Gas chromatograms before and after OPO byproduct treatment as shown in FIGS. 1-9 and Table 4.

Table 4 shows the principal compositional analysis of the filtrates obtained for untreated OPO by-product, examples 1-6 and comparative examples 1-2.

As can be seen from the above Table 4, the untreated OPO by-product has oleic acid content of about 57% and less oleic acid content, and the filtrate obtained by the treatment of the method of the application has oleic acid as the main component, oleic acid content of 80% or more, higher oleic acid content and palmitic acid, stearic acid, linoleic acid and the like as the other components, and the components belong to OPO system, so that the oleic acid prepared by the method of the application is safer and more reliable.

It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps recited in the present disclosure may be performed in parallel or sequentially or in a different order, provided that the desired results of the technical solutions of the present disclosure are achieved, and are not limited herein.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present disclosure, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

The foregoing is merely specific embodiments of the disclosure, but the protection scope of the disclosure is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the disclosure, and it is intended to cover the scope of the disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. A method for separating oleic acid from byproducts of OPO grease is characterized by comprising the following steps:

(2) Preparing crystal slurry:

(3) Crystallization and filter pressing of crystal slurry:

2. The method according to claim 1, wherein in the step (1), the seed crystal comprises 85-100 wt% of stearic acid, 0-20 wt% of palmitic acid triglyceride and 0-15 wt% of glyceryl monostearate;

3. The method according to claim 2, wherein in the step (1), the seed crystal comprises 85wt% of stearic acid, 10wt% of palmitic acid triglyceride, and 5wt% of glyceryl monostearate;

4. The method of claim 1, wherein the crystal slurry prepared in the step (2) meets the following requirements of 25-50wt% of saturated fatty acid, 50-75wt% of unsaturated fatty acid, and 0-5wt% of ester and impurities.

5. The method of claim 1, wherein in the step (2), the stirring rate is at least 200r/min and the stirring time is at least 30min.

6. The method of claim 1, wherein in the step (3), the stirring rate of the crystallization kettle is 10-50 r/min.

7. The method according to claim 1, wherein in the step (3), the temperature is reduced from 70 ℃ to 55 ℃ at a temperature reduction rate of 5 ℃ per hour;

8. The method according to any one of claims 1 to 7, further comprising the step of:

And (5) repeating the steps (4) - (5) for a plurality of times.

9. The method of claim 8, wherein in the step (4), the secondary crystal slurry satisfies the following requirements, by mass, 25-50% of saturated fatty acid, 50-75% of unsaturated fatty acid, and 0-5% of ester and impurity.

10. Oleic acid is prepared by the process of any one of claims 1 to 9.