阅读说明：本技术 一种利用植物废油生产油酸的工艺方法 (Process method for producing oleic acid by using plant waste oil ) 是由 李端春 平晓杰 于 2020-05-14 设计创作，主要内容包括：本发明涉及绿色环保领域,具体涉及一种利用植物废油生产油酸的工艺方法,具体包括以下步骤：第一步,预处理；第二步,裂解；第三步,后处理；第四步,提纯。本发明解决了冷冻压榨法对设备要求低,但是劳动强度高,效率低,不能连续操作；表面活性剂法又称乳化法,该法废水多,分离纯度较低的问题。本发明得到的预处理物较为纯净,除去了95％以上的杂质与色素,为后续裂解提纯、减少设备故障提供了保障,延长了设备的使用周期。(The invention relates to the field of green environmental protection, in particular to a process method for producing oleic acid by using plant waste oil, which comprises the following steps: firstly, preprocessing; secondly, cracking; thirdly, post-treatment; and fourthly, purifying. The invention solves the problems that the freeze pressing method has low requirement on equipment, but has high labor intensity, low efficiency and can not be continuously operated; the surfactant method is also called as emulsification method, and the method has the problems of more waste water and lower separation purity. The pretreatment substance obtained by the method is pure, more than 95% of impurities and pigments are removed, guarantee is provided for subsequent cracking purification and reduction of equipment faults, and the service life of the equipment is prolonged.)

1. A process method for producing oleic acid by using plant waste oil is characterized by comprising the following steps:

first, pretreatment

Firstly, standing and settling vegetable waste oil for 10-12 hours, reserving upper-layer oil, and removing bottom impurities to obtain primary filtered oil; filtering the primary filtered oil to remove suspended and floating impurities to obtain secondary filtered oil;

adding a dilute acid solution into the second-stage filtered grease, stirring the mixture uniformly, then placing the mixture into a settling reaction kettle for settling for 1-2 hours, and filtering the mixture to obtain third-stage filtered grease;

pouring impurity-removing materials into the three-stage filtering grease, stirring for 2-3 h, and filtering again to obtain a pretreated substance;

second, cracking

Adding a cracking catalyst into the pretreated substance, starting stirring, and cracking to obtain a cracking product; wherein the cracking temperature is 200-230 ℃, the cracking pressure is 1.8-2.3 MPa, and the stirring speed is 200-500 rpm;

third, post-treatment

Adding a dilute acid solution into the cracked product again, heating to 60-70 ℃, and stirring for 2-5 hours to obtain a post-treated product;

the fourth step, purification

Purifying the post-treatment substance by adopting a 5-tower series rectification process to obtain oleic acid; wherein the temperature of the rectifying tower is 230-260 ℃, and the pressure of the top of the rectifying tower is 0.2-0.5 kPa.

2. The process for producing oleic acid from waste vegetable oil according to claim 1, wherein the dilute acid solution is an aqueous solution of sulfuric acid having a concentration of 0.1 mol/L; the volume ratio of the secondary filtering oil to the dilute acid solution is 10-50: 1; the volume ratio of the cracking product to the dilute acid solution is 10-20: 1.

3. The process for producing oleic acid from waste vegetable oil as claimed in claim 1, wherein the cracking catalyst is carbon nanotube-supported potassium oxide.

4. The process method for producing oleic acid by using plant waste oil as claimed in claim 3, wherein the preparation step of the carbon nanotube-loaded potassium oxide is as follows:

mixing a carbon nano tube with a sodium hydroxide solution with the mass fraction of 30-50%, performing ultrasonic treatment for 1-3 h, heating to 50-60 ℃, stirring for reaction for 10-15 h, filtering to obtain a solid, drying in an oven with the temperature of 80-90 ℃, then placing in a muffle furnace with the temperature of 500-600 ℃ for 5-8 h, and grinding into powder to obtain carbon nano tube loaded potassium oxide; wherein the solid-to-liquid ratio of the carbon nano tube to the sodium hydroxide solution is 1: 2-5.

5. The process of claim 1, wherein the impurity removing material is modified WS₂Grafting to metal-organic frameworks to form WS₂-an organic framework composite.

6. The process for producing oleic acid from waste vegetable oil as claimed in claim 5, wherein the metal-organic framework compound is a zirconium-based metal-organic framework compound.

7. The process for producing oleic acid from waste vegetable oil according to claim 5 or 6, wherein the metal-organic framework compound is prepared by the following steps:

weighing ZrCl₄Adding into deionized water, stirring to dissolve completely to obtain ZrCl₄A solution; adding terephthalic acid into N, N-dimethylformamide, and stirring uniformly to obtain a terephthalic acid solution; wherein ZrCl₄The solid-to-liquid ratio of the deionized water is 1: 10-15; the mass ratio of the terephthalic acid to the N, N-dimethylformamide is 1: 3-5;

will be described inZrCl₄Dropwise adding the solution into a terephthalic acid solution, stirring while dropwise adding, continuously stirring for 0.5-1 h after completely dropwise adding, pouring into a reaction kettle with a polytetrafluoroethylene lining, sealing, placing in a drying oven at 150-180 ℃, reacting for 8-12 h, cooling, filtering, washing with deionized water for 3 times, washing with ethanol for 3 times, drying at 80-90 ℃, and grinding to powder to obtain a metal organic framework compound; wherein, the ZrCl₄The volume ratio of the solution to the terephthalic acid solution is 3-5: 1.

8. The process for producing oleic acid from waste vegetable oil as claimed in claim 5, wherein the WS solution is prepared from waste vegetable oil₂The modification method comprises the following steps:

s1, weighing WS₂Mixing the nanosheets with 98% concentrated sulfuric acid by mass, stirring uniformly in an ice-water bath, adding potassium ferrate, stirring and reacting for 0.2-0.6 h, heating to 45-50 ℃, and stirring again for 0.2-0.6 h to obtain a reaction solution A; wherein WS₂The solid-liquid ratio of the nanosheets to concentrated sulfuric acid is 1: 15-20; potassium ferrate and WS₂The mass ratio of the nano sheets is 2-3: 1, and the stirring speed is 200-300 rpm;

s2, adding deionized water into the reaction liquid A, heating to 80-100 ℃, stirring for 0.2-0.6 h, and then respectively adding Al (NO)₃)₃And Mg (NO)₃)₃Stirring and reacting for 1-3 h to obtain a reaction solution B; wherein the volume ratio of the reaction liquid A to the deionized water is 1: 2-3; al (NO)₃)₃And WS₂The mass ratio of the nano sheets is 1: 2-3; mg (NO)₃)₃And WS₂The mass ratio of the nano sheets is 1: 2-3, the stirring speed is 300-500 rpm;

s3, pouring the reaction liquid B into deionized water at 0-10 ℃ while the reaction liquid B is hot, adding hydrogen peroxide, stirring uniformly, standing for 1-2 h, filtering to obtain a solid, washing for 3 times by using saturated sodium carbonate, then washing to be neutral by using deionized water, drying in an oven at 80-90 ℃, and crushing in a nano crusher to obtain the modified WS₂Nano powder; wherein the volume ratio of the reaction liquid B to the deionized water at 0-10 ℃ is1: 2-3; the volume ratio of the hydrogen peroxide to the reaction liquid B is 1: 5-10; the stirring speed is 300-500 rpm.

9. The process for producing oleic acid from waste vegetable oil as claimed in claim 5, wherein the WS solution is prepared from waste vegetable oil₂The preparation method of the organic framework composite material comprises the following steps:

(1) weighing the modified WS₂Adding the nano powder into deionized water, stirring uniformly, and performing ultrasonic treatment for 1-2 hours to obtain a liquid M; adding cetyl trimethyl ammonium bromide into deionized water, stirring uniformly, and then dropwise adding 0.1mol/L NaOH solution until the pH value is 11.0-12.0 to obtain liquid N; slowly pouring the liquid N into the liquid M while stirring, carrying out ultrasonic treatment for 1-2 h after the liquid N is completely poured into the liquid M, and then placing the liquid N in a water bath condition at 50-60 ℃ for reaction for 3-5 h to obtain WS₂Pretreatment liquid;

(2)WS₂load graft to organic framework composite:

adding a metal organic framework compound into deionized water, stirring until the mixture is uniform, and slowly adding the mixture into the WS₂Continuously reacting the pretreatment liquid for 10-15 h under the condition of 50-60 ℃ water bath, cooling to room temperature, centrifuging to obtain a solid, washing with deionized water for 3 times, then washing with chloroform for 3 times, and drying at 80-90 ℃ to obtain the organic framework material load WS₂Pretreating a substance;

(3) organic framework material loading WS₂The post-treatment:

loading WS on the organic framework material₂Placing the pre-treated substance in a graphite furnace, vacuumizing, introducing a mixed gas of hydrogen and helium to atmospheric pressure, heating to 250 ℃ at a speed of 5 ℃/min, preserving heat for 2h, heating to 800 ℃ at a speed of 10 ℃/min, preserving heat for 1h, and naturally cooling to room temperature to obtain a solid C; grinding the solid C into powder, mixing with excessive absolute ethyl alcohol, stirring for 0.5-1 h, filtering to obtain a solid, and drying in an oven at 60-70 ℃ to obtain the product WS₂-an organic framework composite.

Technical Field

The invention relates to the field of environmental protection, in particular to a process method for producing oleic acid by using plant waste oil.

Background

The waste vegetable oil refers to a series of oil wastes which lose edible value and are generated in the deep processing process of edible natural vegetable oil and oil for human beings. Waste oil produced in the catering process is also called as catering waste oil. The fatty acid composition of the waste cooking oil is basically consistent with that of fresh edible oil, and the waste cooking oil mainly contains oleic acid and linoleic acid. The oil-containing soapstock produced in the food processing process is a byproduct produced in the refining of various vegetable oils, the production amount is 2-3% of the total oil production amount, and the composition and the properties of the oil-containing soapstock are determined by fatty acid in raw materials.

At present, the waste edible oil and fat in China are not reasonably utilized. In contrast, waste edible oils and fats have become an environmental pollutant and have impacted food safety. The waste edible oil is reasonably recycled, and the oil can replace petroleum resources to produce important oil chemical raw materials. The waste vegetable oil contains a large amount of stearic acid and oleic acid, and the oleic acid can be produced and processed by hydrolyzing and separating the waste edible oil. The following not enough exists in the processing procedure of present plant waste oil, and first, lack the preliminary treatment to waste oil, contain more impurity and pigment in the plant waste oil, direct processing uses influences equipment normal operating, and is great to equipment damage. Second, methods for purifying oleic acid include a freeze-squeezing method, a surfactant method, and the like. The freeze-pressing method has low requirements on equipment, but has high labor intensity and low efficiency and can not be continuously operated; the surfactant method is also called emulsification method, and the method has more waste water and lower separation purity.

Disclosure of Invention

Aiming at the problems, the invention provides a process method for producing oleic acid by using plant waste oil, which comprises the following steps:

first, pretreatment

Firstly, standing and settling vegetable waste oil for 10-12 hours, reserving upper-layer oil, and removing bottom impurities to obtain primary filtered oil; filtering the primary filtered oil to remove suspended and floating impurities to obtain secondary filtered oil;

adding a dilute acid solution into the second-stage filtered grease, stirring the mixture uniformly, then placing the mixture into a settling reaction kettle for settling for 1-2 hours, and filtering the mixture to obtain third-stage filtered grease;

pouring impurity-removing materials into the three-stage filtering grease, stirring for 2-3 h, and filtering again to obtain a pretreated substance;

second, cracking

Adding a cracking catalyst into the pretreated substance, starting stirring, and cracking to obtain a cracking product; wherein the cracking temperature is 200-230 ℃, the cracking pressure is 1.8-2.3 MPa, and the stirring speed is 200-500 rpm;

third, post-treatment

Adding a dilute acid solution into the cracked product again, heating to 60-70 ℃, and stirring for 2-5 hours to obtain a post-treated product;

the fourth step, purification

Purifying the post-treatment substance by adopting a 5-tower series rectification process to obtain oleic acid; wherein the temperature of the rectifying tower is 230-260 ℃, and the pressure of the top of the rectifying tower is 0.2-0.5 kPa.

Preferably, the dilute acid solution is a sulfuric acid aqueous solution with the concentration of 0.1 mol/L.

Preferably, the volume ratio of the secondary filtering grease to the dilute acid solution is 10-50: 1.

Preferably, the volume ratio of the cracking product to the dilute acid solution is 10-20: 1.

Preferably, the cracking catalyst is carbon nanotube-supported potassium oxide.

Preferably, the preparation steps of the carbon nanotube-supported potassium oxide are as follows:

mixing a carbon nano tube with a sodium hydroxide solution with the mass fraction of 30-50%, performing ultrasonic treatment for 1-3 h, heating to 50-60 ℃, stirring for reaction for 10-15 h, filtering to obtain a solid, drying in an oven with the temperature of 80-90 ℃, then placing in a muffle furnace with the temperature of 500-600 ℃ for 5-8 h, and grinding into powder to obtain carbon nano tube loaded potassium oxide; wherein the solid-to-liquid ratio of the carbon nano tube to the sodium hydroxide solution is 1: 2-5.

Preferably, the impurity removal material is modified WS₂Grafting to metal-organic frameworks to form WS₂-an organic framework composite.

Preferably, the metal-organic framework compound is a zirconium-based metal-organic framework compound.

Preferably, the preparation method of the metal-organic framework compound comprises the following steps:

weighing ZrCl₄Adding intoStirring the mixture in ionized water until the mixture is completely dissolved to obtain ZrCl₄A solution; adding terephthalic acid into N, N-dimethylformamide, and stirring uniformly to obtain a terephthalic acid solution; wherein ZrCl₄The solid-to-liquid ratio of the deionized water is 1: 10-15; the mass ratio of the terephthalic acid to the N, N-dimethylformamide is 1: 3-5;

reacting the ZrCl₄Dropwise adding the solution into a terephthalic acid solution, stirring while dropwise adding, continuously stirring for 0.5-1 h after completely dropwise adding, pouring into a reaction kettle with a polytetrafluoroethylene lining, sealing, placing in a drying oven at 150-180 ℃, reacting for 8-12 h, cooling, filtering, washing with deionized water for 3 times, washing with ethanol for 3 times, drying at 80-90 ℃, and grinding to powder to obtain a metal organic framework compound; wherein, the ZrCl₄The volume ratio of the solution to the terephthalic acid solution is 3-5: 1.

Preferably, said WS₂The modification method comprises the following steps:

s1, weighing WS₂Mixing the nanosheets with 98% concentrated sulfuric acid by mass, stirring uniformly in an ice-water bath, adding potassium ferrate, stirring and reacting for 0.2-0.6 h, heating to 45-50 ℃, and stirring again for 0.2-0.6 h to obtain a reaction solution A; wherein WS₂The solid-liquid ratio of the nanosheets to concentrated sulfuric acid is 1: 15-20; potassium ferrate and WS₂The mass ratio of the nano sheets is 2-3: 1, and the stirring speed is 200-300 rpm;

s2, adding deionized water into the reaction liquid A, heating to 80-100 ℃, stirring for 0.2-0.6 h, and then respectively adding Al (NO)₃)₃And Mg (NO)₃)₃Stirring and reacting for 1-3 h to obtain a reaction solution B; wherein the volume ratio of the reaction liquid A to the deionized water is 1: 2-3; al (NO)₃)₃And WS₂The mass ratio of the nano sheets is 1: 2-3; mg (NO)₃)₃And WS₂The mass ratio of the nano sheets is 1: 2-3, the stirring speed is 300-500 rpm;

s3, pouring the reaction liquid B into deionized water at 0-10 ℃ while the reaction liquid B is hot, adding hydrogen peroxide, stirring uniformly, standing for 1-2 h, filtering to obtain a solid, and washing with saturated sodium carbonateWashing with deionized water to neutrality for 3 times, drying in an oven at 80-90 deg.C, and pulverizing in a nanometer pulverizer to obtain modified WS₂Nano powder; wherein the volume ratio of the reaction liquid B to deionized water at 0-10 ℃ is 1: 2-3; the volume ratio of the hydrogen peroxide to the reaction liquid B is 1: 5-10; the stirring speed is 300-500 rpm.

Preferably, said WS₂The preparation method of the organic framework composite material comprises the following steps:

(1) weighing the modified WS₂Adding the nano powder into deionized water, stirring uniformly, and performing ultrasonic treatment for 1-2 hours to obtain a liquid M; adding cetyl trimethyl ammonium bromide into deionized water, stirring uniformly, and then dropwise adding 0.1mol/L NaOH solution until the pH value is 11.0-12.0 to obtain liquid N; slowly pouring the liquid N into the liquid M while stirring, carrying out ultrasonic treatment for 1-2 h after the liquid N is completely poured into the liquid M, and then placing the liquid N in a water bath condition at 50-60 ℃ for reaction for 3-5 h to obtain WS₂Pretreatment liquid;

(2)WS₂load graft to organic framework composite:

adding a metal organic framework compound into deionized water, stirring until the mixture is uniform, and slowly adding the mixture into the WS₂Continuously reacting the pretreatment liquid for 10-15 h under the condition of 50-60 ℃ water bath, cooling to room temperature, centrifuging to obtain a solid, washing with deionized water for 3 times, then washing with chloroform for 3 times, and drying at 80-90 ℃ to obtain the organic framework material load WS₂Pretreating a substance;

(3) organic framework material loading WS₂The post-treatment:

loading WS on the organic framework material₂Placing the pre-treated substance in a graphite furnace, vacuumizing, introducing a mixed gas of hydrogen and helium to atmospheric pressure, heating to 250 ℃ at a speed of 5 ℃/min, preserving heat for 2h, heating to 800 ℃ at a speed of 10 ℃/min, preserving heat for 1h, and naturally cooling to room temperature to obtain a solid C; grinding the solid C into powder, mixing with excessive absolute ethyl alcohol, stirring for 0.5-1 h, filtering to obtain a solid, and drying in an oven at 60-70 ℃ to obtain the product WS₂-organic framework compoundingA material.

The invention has the beneficial effects that:

1. according to the process method, the waste plant oil is pretreated firstly, the finally obtained pretreated matter is relatively pure, more than 95% of impurities and pigments are removed, guarantee is provided for subsequent cracking purification and reduction of equipment faults, and the service cycle of the equipment is prolonged; the second step belongs to the cracking process, the pretreated plant waste oil is treated by a catalytic cracking method, and the obtained cracking product has light color and good smell and can meet the market demand; the third step belongs to the post-treatment process of the second step cracking, and dilute acid is added during the post-treatment process to convert the salts generated by the second step cracking into acid, so that the purification of the fourth step is facilitated; the rectification tower with high-efficiency separation capacity is used for the oleic acid purification in the fourth step, so that the purification efficiency is improved.

2. During pretreatment, large blocks and impurities with large mass are firstly filtered by standing, then diluted acid solution is added for treatment, so that some impurities dissolved in grease are removed by diluted acid, and then the residual impurities which are not treated and are not cleaned are adsorbed by using impurity removing materials. Wherein the impurity-removing material is WS₂-an organic framework composite; the preparation process of the material comprises the steps of preparing the zirconium-based organic framework and then carrying out WS treatment₂Modifying the modified WS₂Capable of being loaded and grafted on a zirconium-based organic framework and then grafting WS to the load₂The zirconium-based organic framework is subjected to post-treatment in a high-temperature environment and H₂The WS is obviously reduced in the process of carrying out thermal reduction treatment in the atmosphere of/He gas₂The oxygen-containing functional group number on the surface can still be combined with the grafting of the organic framework material, thereby effectively ensuring WS₂-integrity of the organic framework composite clad structure.

3. The catalyst used in the cracking process is carbon nanotube loaded potassium oxide, and the catalyst has high catalytic activity, is pollution-free in the whole process and is environment-friendly. The preparation of the catalyst also adopts a simple and green process to successfully prepare the carbon nano tube loaded high-activity potassium oxide catalyst. When the catalyst is used, the yield of the product can reach more than 97%, and the catalyst can be recycled after simple treatment. According to the experimental result of the invention, after the potassium ion leaching agent is repeatedly used for 5 times, the leaching rate of potassium ions is still lower than 0.1mg/L and is far lower than the maximum limit value of 5mg/L specified by international standards.

4. The impurity removing material prepared by the invention can be quickly and uniformly distributed in the vegetable oil within a certain concentration range without forming agglomeration, on one hand, the WS is used₂Modified and grafted on the surface of the organic framework material to ensure that the surface of the organic framework material contains hydroxyl which can reduce the crosslinking density of vegetable oil, thereby WS₂The flexural modulus of the organic framework composite in greases will be much lower than the organic framework material alone or the unmodified WS₂Flexural modulus in grease; another aspect is WS₂The hydrophobic substance has the structural characteristics changed after being modified so as to have the surface activity effect, so that the hydrophobic substance has the surface activity effect in WS₂After dispersion of the organic framework composite in the oil, WS₂The oil-water microemulsion can adsorb a small amount of water in the oil and fat so as to be positioned at an oil-water two-phase interface to form a water-in-oil microemulsion, so that the oil-water microemulsion can be uniformly dispersed in the oil and fat and is easier to separate subsequently. Furthermore, WS₂Magnesium and aluminum are also introduced during the modification process, the two elements being introduced in view of WS₂Special layer structure, thereby WS₂Magnesium ions and aluminum ions are introduced into the interlayer position of the layered structure, so that the capability of adsorbing impurities and pigments is greatly improved.

Detailed Description

The invention is further described with reference to the following examples.