阅读说明：本技术 一种采用酶法与酸碱法耦合生产生物柴油的方法 (Method for producing biodiesel by coupling enzyme method and acid-base method ) 是由 焦记稳 朱罗乐 于 2021-08-13 设计创作，主要内容包括：本发明公开了一种采用酶法与酸碱法耦合生产生物柴油的方法,包括：将原料油,液体脂肪复合酶,稀甲醇和反应助剂一起混合同时发生水解,脂化,转脂化三种反应。将混合反应液进行分离,得到油相,水相,同时回收酶继续反复使用。将油相干燥后加入酸催化剂,脂肪酸反应完毕认为该阶段反应结束,同干燥空气带走过量甲醇。将反应完的油相通过加碱中和至酸价小于0.5KOHmg/g。将调和完毕的油相进塔蒸馏,得到植物沥青,轻组分,生物柴油。本发明可以有效地解决目前大部分传统生物柴油工厂由于场地不足,更改报建新上装备难度大,通过引进酶法工艺,大幅度降低酸碱用量,减少污染排放,缩短反应时间,减小能耗,同时降低改造成本,一举多得。(The invention discloses a method for producing biodiesel by coupling an enzyme method and an acid-base method, which comprises the following steps: raw oil, liquid fat complex enzyme, diluted methanol and reaction auxiliary agent are mixed together to simultaneously carry out three reactions of hydrolysis, esterification and conversion esterification. Separating the mixed reaction solution to obtain an oil phase and a water phase, and simultaneously recovering the enzyme for continuous repeated use. And (3) drying the oil phase, adding an acid catalyst, and after the fatty acid reaction is finished, considering that the reaction at the stage is finished, and taking away excessive methanol with dry air. Neutralizing the reacted oil phase by adding alkali until the acid value is less than 0.5 KOHmg/g. And (3) distilling the blended oil phase in a tower to obtain the plant asphalt, the light components and the biodiesel. The invention can effectively solve the problem that most of the traditional biodiesel factories have large difficulty in changing new equipment due to insufficient site, greatly reduces the acid and alkali dosage, reduces pollution emission, shortens the reaction time, reduces energy consumption, reduces the modification cost and achieves multiple purposes by introducing an enzyme process.)

1. A method for producing biodiesel by coupling an enzyme method and an acid-base method is characterized by comprising the following steps:

(1) mixing raw oil, liquid fat complex enzyme, diluted methanol and reaction auxiliary agent together, and performing three reactions of hydrolysis, lipidation and conversion lipidation at 30-60 ℃ to obtain a final mixed solution, wherein the acid value is 5-15KOHmg/g, and the triglyceride is basically converted; wherein the liquid fat complex enzyme consists of esterase, lipase, sulfatase and phosphatase;

(2) separating the mixed solution to obtain an oil phase, a water phase and an enzyme phase, recycling the enzyme phase, carrying out flash evaporation on the water phase to obtain diluted methanol and crude glycerol, and enabling the oil phase to enter the next step;

(3) the oil phase enters an acid catalysis reaction kettle, is heated to the temperature of 100-;

(4) adding the reaction solution into an alkali catalytic reaction kettle, adding alkali to adjust the pH value, and reducing the acid value to 0.1-0.5KOHmg/g to finish blending;

(5) the blended raw materials are directly fed into a tower for distillation to obtain light components, biodiesel and heavy components.

2. The method of claim 1, wherein the feedstock oil comprises vegetable oil, animal oil, microbial oil, or waste oil.

3. The method of claim 2, wherein the feedstock oil comprises castor oil, palm oil, rapeseed oil, soybean oil, peanut oil, corn oil, cottonseed oil, rice bran oil, jatropha oil, shinyleaf yellowhorn oil, jatropha oil, fish oil, tallow, lard, mutton fat, yeast fat, microalgae fat, hogwash oil, illegal cooking oil, or acidified oil.

4. The method as claimed in claim 1, wherein the amount of the liquid fatty complex enzyme is 0.1-3% of the weight of the raw oil, the amount of the dilute methanol is 12-20% of the weight of the raw oil, and the amount of the reaction auxiliary agent is 0.2-10% of the weight of the raw oil.

5. The method as claimed in claim 1 or 4, wherein the liquid fat complex enzyme is composed of esterase, lipase, sulfatase and phosphatase according to the mass ratio of 1-2:2-5:1-3: 1-2.

6. The method of claim 1, wherein the dilute methanol is a methanol solution having a concentration of 60% w/w or more.

7. The method of claim 1, wherein the reaction auxiliary agent comprises an activator and a protectant, wherein the activator comprises an esteroyl COA synthetase, and the protectant comprises a sulfate-based protectant, a silicate-based protectant, and a phosphate-based protectant, and preferably, the protectant comprises at least one of sodium sulfate, sodium silicate, and sodium phosphate.

8. The method of claim 1, wherein the acid catalyst comprises concentrated sulfuric acid and methanesulfonic acid.

9. The method of claim 1, wherein part of methanol and water in the water phase in the step (2) can be recovered and used in the step (1), the rest part is pumped into a methanol recovery distillation tower for reduced pressure distillation, dealcoholization and dehydration are carried out in the system for concentration to obtain crude glycerol with the content of 70-85%, and the condensed water and methanol are recovered to the step (1) for recycling.

10. The method of claim 1, wherein the condensed water in step (3) and the diluted methanol formed from methanol are used directly back to step (1) without further purification or further temperature reduction.

Technical Field

The invention relates to a method for producing biodiesel, in particular to a method for producing biodiesel by coupling an enzyme method and an acid-base method. The invention belongs to the technical field of energy development and utilization.

Background

Biodiesel (Biodiesel) is named as fatty acid methyl ester, and is a renewable diesel fuel which can replace petroleum diesel and is prepared by taking oil crops such as soybean, rape, cotton, palm and the like, aquatic plant oil and fat such as wild oil plants, engineering microalgae and the like, animal oil and fat, food and beverage waste oil and the like as raw materials and methanol through ester exchange or thermochemical process under the action of a catalyst. The carbon chain of the biodiesel consists of C12-C18, and the carbon chain of the petroleum diesel consists of C14-C16, so that the biodiesel and the petroleum diesel have basically the same carbon chain, and the biodiesel can replace the petroleum diesel.

At present, methods for producing biodiesel mainly comprise an acid-base method, an enzyme method and a method for coupling the enzyme method and the alkali method. The traditional acid-base method adopts acid-catalyzed ester exchange and base-catalyzed transesterification, so that the whole acid-base dosage is large, the amount of wastewater is large, the yield is low, and manufacturers basically seek new technology to modify and promote the existing production line so as to meet the environmental protection requirement and improve the comprehensive income. The reaction time of the pure enzyme process is long, and the full enzyme process cannot be used due to the objective conditions of large overall change, high modification cost, low site cost and the like of modification projects. In the method of coupling the enzyme method and the alkaline method, the recycling cost of the enzyme preparation is higher, the acid value of the raw material oil is too high, and the final acid value cannot be reduced to below 2.5, and the scheme has practical application opportunities and value only when the original acid value of the raw material is within 10.

Aiming at the technical current situation, the raw material characteristics and the input-output ratio requirement pursued by enterprises in the domestic biodiesel industry, the invention creatively provides a process route of a method for coupling an enzyme method and an acid-base method, can well meet the market demand and improve the productivity.

Disclosure of Invention

The invention aims to provide a method for producing biodiesel by coupling an enzyme method and an acid-base method.

In order to achieve the purpose, the invention adopts the following technical means:

the invention relates to a method for producing biodiesel by coupling an enzyme method and an acid-base method, which comprises the following steps:

(1) mixing raw oil, liquid fat complex enzyme, diluted methanol and reaction auxiliary agent together, and performing three reactions of hydrolysis, lipidation and conversion lipidation at 30-60 ℃ to obtain a final mixed solution, wherein the acid value is 5-15KOHmg/g, and the triglyceride is basically converted; wherein the liquid fat complex enzyme consists of esterase, lipase, sulfatase and phosphatase;

(2) separating the mixed solution to obtain an oil phase, a water phase and an enzyme phase, recycling the enzyme phase, carrying out flash evaporation on the water phase to obtain diluted methanol and crude glycerol, and enabling the oil phase to enter the next step;

(3) the oil phase enters an acid catalysis reaction kettle, is heated to 120 ℃ below 100 ℃ and is further dehydrated to below 1000ppm, then methanol is added and an acid catalyst is added to reduce the acid value to 0.8-1.2, and the temperature is kept for 30 minutes after the dealcoholization at 120 ℃, which is regarded as the reaction is finished;

(4) adding the reaction solution into an alkali catalytic reaction kettle, adding alkali to adjust the pH value, and reducing the acid value to 0.1-0.5KOHmg/g to finish blending;

(5) the blended raw materials are directly fed into a tower for distillation to obtain light components, biodiesel and heavy components (plant asphalt).

Preferably, the raw oil comprises vegetable oil, animal oil, microbial oil or waste oil.

More preferably, the raw oil comprises castor oil, palm oil, rapeseed oil, soybean oil, peanut oil, corn oil, cottonseed oil, rice bran oil, jatropha oil, shinyleaf yellowhorn oil, jatropha oil, fish oil, beef tallow, lard, mutton fat, yeast fat, microalgae fat, hogwash oil, swill-cooked dirty oil or acidified oil.

Preferably, the dosage of the liquid fat complex enzyme is 0.1-3% of the weight of the raw oil, the dosage of the dilute methanol is 12-20% of the weight of the raw oil, and the dosage of the reaction auxiliary agent is 0.2-10% of the weight of the raw oil.

Preferably, the liquid fat complex enzyme consists of esterase, lipase, sulfatase and phosphatase according to the mass ratio of 1-2:2-5:1-3: 1-2.

Wherein, the diluted methanol is preferably methanol solution with the concentration of more than 60% w/w.

Preferably, the reaction auxiliary agent comprises an activator and a protective agent, wherein the activator comprises acyl-CoA synthetase (acyl-CoA synthetase), the protective agent comprises a sulfate protective agent, a silicate protective agent and a phosphate protective agent, and more preferably, the protective agent comprises at least one of sodium sulfate, sodium silicate and sodium phosphate.

Among them, preferably, the acid catalyst includes concentrated sulfuric acid and methanesulfonic acid.

Preferably, part of methanol and water in the water phase in the step (2) can be recycled and used in the step (1), the rest part of methanol and water is pumped into a methanol recovery distillation tower through a pump to be distilled under reduced pressure, the methanol is removed from the system, dehydration and concentration are carried out to obtain crude glycerol with the content of 70-85%, and condensed water and methanol are recycled to the step (1).

Wherein, preferably, the condensed water in the step (3) and the diluted methanol formed by the methanol are directly returned to the step (1) for use without refining or further temperature reduction.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention couples the pretreatment process of the acid-base method with the enzyme method process, forms pre-esterification and sedimentation impurity removal in the same process, finally greatly reduces the acid-base dosage, reduces the acid residue and sewage quantity, shortens the acid catalytic reaction time because water and impurities are removed and more than 90% of methyl ester is formed, removes the alkali catalytic reaction process, adds alkali only to adjust the pH value, and basically has no soap generation because the acid value is reduced to about 1, most of the acid value is formed by short-chain acidic substances such as formic acid, acetic acid and the like, and the overall yield is superior to that of the acid-base method and is higher than that of the enzyme-base method process.

2. The diluted methanol obtained by flash evaporation can be recycled after more than 60 percent, and compared with the traditional methanol recovery and rectification, the diluted methanol can be recycled after more than 90 percent, so that a large amount of energy consumption can be saved, the equipment investment cost is reduced, and the integral single-ton energy consumption is saved. The enzyme phase can be recycled for multiple times, and the catalyst cost is reduced. The crude glycerol does not contain salt, the whole process is characterized in that the crude glycerol is completely generated and separated, the glycerol can be obtained after alkali catalysis unlike the traditional method, and the traditional process has larger operation difficulty in clean separation.

3. The acid catalysis reaction kettle has a dehydration function, and the alcohol can be removed by continuously heating after the reaction is finished, so that the obtained crude methyl ester has low water-containing alcohol content, and the subsequent process is favorably carried out efficiently.

4. The function of the alkali catalytic reaction kettle is adjusted to be a pH value adjusting intermediate tank, the final acid value is controlled, ester exchange reaction is not carried out, the energy consumption is low, the time is short, secondary effective utilization of equipment is realized, and the reconstruction cost is reduced.

5. The transformation process is simple, the production equipment basically does not need to be changed too much, the pretreatment equipment and the cache tank or the raw material tank are linked to form the coupling of the liquid enzyme catalytic reaction and the sedimentation impurity removal process, the investment is small, the number of newly added equipment is small, the operation difference of workers is not large, and the training is easy. And the enzyme recovery process is adopted, and the catalyst can be repeatedly used, so that the cost of the single-ton catalyst is effectively reduced, and the cost is low.

Drawings

FIG. 1 is a flow chart of the method of the present invention.

Detailed Description

The present invention is further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become more apparent as the description of the specific embodiments proceeds. The examples are illustrative only and do not limit the scope of the present invention in any way. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be made without departing from the spirit and scope of the invention.

Example 1

As shown in figure 1, a method for producing biodiesel by coupling an enzyme method and an acid-base method comprises the following preparation steps:

s1, mixing raw oil (illegal cooking oil with an acid value of 140KOHmg/g, a saponification value of 190, water impurity of 3% and a pH value of 4.8), liquid fat complex enzyme (composed of esterase, lipase, sulfatase and phosphatase according to a mass ratio of 1:2:1: 1), 60% w/w diluted methanol, a reaction auxiliary agent (composed of activator acyl COA synthetase and a protective agent according to an equal mass ratio, wherein the protective agent is obtained by mixing sodium sulfate, sodium silicate and sodium phosphate according to an equal mass ratio), hydrolyzing at 40 ℃, esterifying and converting into lipidation to obtain a final mixed solution with a concentration of 12KOHmg/g (triglyceride is basically converted); wherein the dosage of the liquid fatty complex enzyme is 2 percent of the weight of the raw oil, the dosage of the dilute methanol is 15 percent of the weight of the raw oil, and the dosage of the reaction auxiliary agent is 5 percent of the weight of the raw oil;

s2 separating the mixed solution to obtain oil phase, water phase and enzyme phase, and recycling the enzyme phase. The water phase is flashed to obtain diluted methanol for reuse, crude glycerol is obtained for sale, and the oil phase enters the next step;

the oil phase of S3 enters an acid catalysis reaction kettle, is heated to 120 ℃ and is further dehydrated to below 1000ppm, then methanol is added and an acid catalyst (concentrated sulfuric acid) is added to reduce the acid value to 1.2KOHmg/g, the temperature is kept for 30 minutes after the dealcoholization at 120 ℃, and the reaction is considered to be finished;

s4, pumping the reaction liquid into an alkali catalytic reaction kettle, adding sodium hydroxide to adjust the pH value, and reducing the acid value to 0.3KOHmg/g to finish the blending.

The S5 blended raw materials directly enter a tower for distillation to obtain light components, biodiesel and heavy components.

The qualified biodiesel is obtained after the 5 steps.

Part of methanol and water in the water phase in the step S2 can be recycled and used in the step S1, the rest part is pumped into a methanol recovery distillation tower for reduced pressure distillation, dealcoholization and dehydration are carried out in the system for concentration to obtain crude glycerol with the content of 75%, and the condensed water and methanol are recycled to S1 for reuse.

The diluted methanol formed by the condensed water and the methanol in the step S3 is directly returned to S1 for use without refining or further temperature reduction. The final acid ester of S3 was 1.2KOHmg/g, after S4 blending, 0.3KOHmg/g, and the final product after S5 distillation was 0.32 KOHmg/g.

Example 2

A method for producing biodiesel by coupling an enzyme method and an acid-base method comprises the following preparation steps:

s1 mixing raw oil (swill-cooked dirty oil, acid value 68KOHmg/g, saponification value 186, PH value 6.6 and water content 1.2%), liquid fat complex enzyme (composed of esterase, lipase, sulfatase and phosphatase according to mass ratio 1:3:2: 2), 60% w/w diluted methanol, reaction auxiliary agent (composed of activator acyl COA synthetase and protective agent according to equal mass ratio, wherein the protective agent is obtained by mixing sodium sulfate, sodium silicate and sodium phosphate according to equal mass ratio), hydrolyzing, esterifying and converting into lipidation at 50 deg.C to obtain final 12KOHmg/g (triglyceride basically converted); wherein the dosage of the liquid fatty complex enzyme is 5 percent of the weight of the raw oil, the dosage of the dilute methanol is 10 percent of the weight of the raw oil, and the dosage of the reaction auxiliary agent is 7 percent of the weight of the raw oil;

s2 separating the mixed solution to obtain oil phase, water phase and enzyme phase, and recycling the enzyme phase. The water phase is flashed to obtain diluted methanol for reuse, crude glycerol is obtained for sale, and the oil phase enters the next step;

the oil phase of S3 enters an acid catalysis reaction kettle, is heated to 100 ℃ and is further dehydrated to below 1000ppm, then methanol is added and an acid catalyst (methanesulfonic acid) is added to reduce the acid value to 0.96KOHmg/g, the temperature is kept for 30 minutes under 100 ℃, and the reaction is considered to be finished;

s4, pumping the reaction liquid into an alkali catalytic reaction kettle, adding sodium hydroxide to adjust the pH value, and reducing the acid value to 0.23KOHmg/g to finish the blending.

The S5 blended raw materials directly enter a tower for distillation to obtain light components, biodiesel and heavy components.

The qualified biodiesel is obtained after the 5 steps.

Part of methanol and water in the water phase in the step S2 can be recycled and used in the step S1, the rest part is pumped into a methanol recovery distillation tower for reduced pressure distillation, dealcoholization and dehydration are carried out in the system for concentration to obtain crude glycerol with the content of 75%, and the condensed water and methanol are recycled to S1 for reuse.

The diluted methanol formed by the condensed water and the methanol in the step S3 is directly returned to S1 for use without refining or further temperature reduction. The crude methyl ester having a semi-finished oleic acid value of 0.96mgKOH/g obtained in step S3 was 0.23KOHmg/g after S4 blending, and the finished product after S5 distillation was 0.22 KOHmg/g.

Example 3

A method for producing biodiesel by coupling an enzyme method and an acid-base method comprises the following preparation steps:

s1 mixing raw oil (acid value 160KOHmg/g, saponification value 193, pH value 4.5 and water content 2.15%), liquid fat complex enzyme (composed of esterase, lipase, sulfatase and phosphatase according to the mass ratio of 1:3:2: 1), 60% w/w diluted methanol, reaction auxiliary agent (composed of activator ester acyl COA synthetase and protective agent according to the equal mass ratio, wherein the protective agent is obtained by mixing sodium sulfate, sodium silicate and sodium phosphate according to the equal mass ratio), hydrolyzing, esterifying and converting into lipidation at 35 ℃ to obtain final mixed solution 12KOHmg/g (triglyceride is basically converted); wherein the dosage of the liquid fat complex enzyme is 3 percent of the weight of the raw oil, the dosage of the dilute methanol is 18 percent of the weight of the raw oil, and the dosage of the reaction auxiliary agent is 3 percent of the weight of the raw oil;

s2 separating the mixed solution to obtain oil phase, water phase and enzyme phase, and recycling the enzyme phase. The water phase is flashed to obtain diluted methanol for reuse, crude glycerol is obtained for sale, and the oil phase enters the next step;

the oil phase of S3 enters an acid catalysis reaction kettle, is heated to 120 ℃ and is further dehydrated to below 1000ppm, then methanol is added and an acid catalyst (concentrated sulfuric acid) is added to reduce the acid value to 1.14KOHmg/g, the temperature is kept for 30 minutes after the dealcoholization at 120 ℃, and the reaction is considered to be finished;

s4, the reaction liquid is injected into an alkali catalytic reaction kettle, and sodium hydroxide is added to adjust the pH value to reduce the acid value to 0.36KOHmg/g, which is regarded as the end of blending.

The S5 blended raw materials directly enter a tower for distillation to obtain light components, biodiesel and heavy components.

The qualified biodiesel is obtained after the 5 steps.

Part of methanol and water in the water phase in the step S2 can be recycled and used in the step S1, the rest part is pumped into a methanol recovery distillation tower for reduced pressure distillation, dealcoholization and dehydration are carried out in the system for concentration to obtain crude glycerol with the content of 75%, and the condensed water and methanol are recycled to S1 for reuse.

The diluted methanol formed by the condensed water and the methanol in the step S3 is directly returned to S1 for use without refining or further temperature reduction. The semi-finished oil obtained in step S3 was crude methyl ester with an acid value of 1.14mgKOH/g, which was 0.36KOHmg/g after S4 blending, and 0.33KOHmg/g after S5 distillation.

The results of acid value detection of the biodiesel prepared by the three examples are shown in table 1, and it can be seen that the acid values are all less than 0.5, and the acid values of the products meet the requirements of national and European standards.

TABLE 1

Examples	Example 1	Example 2	Example 3
				Acid value	0.32mgKOH/g	0.22mgkOH/g	0.33mgKOH/g