CN113773174B - Method for simultaneously extracting dihydric alcohol and organic acid ester from microbial fermentation broth - Google Patents
Method for simultaneously extracting dihydric alcohol and organic acid ester from microbial fermentation broth Download PDFInfo
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Abstract
The invention provides a method for simultaneously extracting dihydric alcohol and organic acid ester from microbial fermentation liquor, which comprises the following steps: s1) separating the bacteria-carrying fermentation liquor which contains dihydric alcohol and organic acid as main fermentation products by an ultrafiltration membrane, removing thalli and protein, and obtaining the fermentation liquor treated by the ultrafiltration membrane; s2) mixing the fermentation liquor treated by the ultrafiltration membrane with glycerol, adjusting the pH value to be alkaline, and carrying out reduced pressure distillation on the system to remove water to obtain concentrated fermentation liquor; s3) mixing the concentrated fermentation liquor with the monohydric alcohol compound, adjusting the pH value to 2-3 by adopting inorganic acid, and filtering to remove precipitated salts to obtain filtrate; s4) mixing the filtrate obtained in S3) with a catalyst, carrying out esterification reaction on organic acid and a monohydric alcohol compound to generate organic acid ester, and then separating the monohydric alcohol compound and the organic acid ester through reduced pressure distillation; s5) adjusting the pH value of the distillation residue obtained in the step S4) to be neutral, and carrying out rectification separation to obtain the dihydric alcohol.
Description
Technical Field
The invention relates to the technical field of bioengineering, in particular to a method for simultaneously extracting dihydric alcohol and organic acid ester from microbial fermentation liquor.
Background
The dihydric alcohol is a series of compounds containing two hydroxyl groups (such as 1, 2-propylene glycol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, isoprene glycol, etc.). The dihydric alcohol has wide industrial application, and can be used as a cosmetic humectant, an antiseptic, a food flavor modifier, a drug synthesis intermediate, a fuel and a fuel additive, a polymer with high added value and the like.
Currently, glycols are available by chemical and biological synthesis. Due to serious ecological pollution caused by chemical methods, limited petrochemical resources used, and production safety problems such as high temperature and high pressure, the microbial fermentation method with mild reaction conditions and using renewable resources as raw materials gradually becomes the mainstream method for the industrial production of dihydric alcohol. However, the dihydric alcohol produced by the microbial fermentation method always has the problem of overhigh cost, so that the development of the bio-based dihydric alcohol industry in China is slower than that in foreign countries. Taking 1, 3-propanediol as an example, the main industrial application is the polymerization with dimethyl terephthalate to produce polytrimethylene terephthalate (PTT). PTT can be further made into fiber and engineering plastics through processing, and the PTT can be widely applied to the clothing field and the home textile field due to the excellent stretch resilience, soft comfort and low-temperature normal-pressure dyeing property of the PTT. By 2019, the global market for PTT fibers has reached $ 13 million, with annual growth rates as high as 14.44%. The industrial production of PTT is mainly limited by the feedstock 1, 3-propanediol. Since 2000, the technology for the biological preparation of 1, 3-propanediol has been monopolized abroad. Although China successfully realizes the industrial production of 1, 3-propylene glycol by a glycerol fermentation method after 2014, breaks monopoly of bio-based 1, 3-propylene glycol in international market, the market price of crude glycerol is influenced by global petroleum and biodiesel markets and has very large fluctuation (1-3 yuan/kg), so that the cost of bio-based 1, 3-propylene glycol produced in China is too high, and the application of the bio-based 1, 3-propylene glycol in PTT production is severely limited. How to optimize and improve the technology for producing 1, 3-propanediol by a microbial fermentation method and reduce the production cost is the key for accelerating the future market development of PTT in China.
It is known that, while a diol is produced by a microorganism through fermentation, a considerable portion of a substrate (saccharide, glycerol, etc.) is metabolized into various organic acid byproducts (lactic acid, formic acid, acetic acid, propionic acid, butyric acid, succinic acid, pyruvic acid, etc.), thereby maintaining intracellular redox balance and obtaining energy (ATP). These organic acid by-products not only lower the fermentation yield of the glycols, but also severely affect the final purity and yield of the glycols. On the contrary, if in the downstream purification process, various organic acid byproducts can be efficiently separated and recovered to form high value-added products, so that the co-production with the dihydric alcohol is realized, the utilization rate and the fermentation capacity of the substrate are greatly improved, and the cost for producing the dihydric alcohol by a microbial fermentation method is indirectly reduced. However, the current industrial purification method mainly uses ion exchange resin or electrodialysis membrane technology (US 7,919,658B 2) to desalt the fermentation broth, and then concentrate and rectify the diol. In this process, inorganic salts and organic acid salts in the fermentation broth are separated, and a large amount of high-salt wastewater is formed, which not only pollutes the environment, but also makes it difficult to recover the organic acid.
CN202110197252.0 utilizes the characteristic that organic acid ammonium salt is easy to be decomposed by heat, and 1, 3-propylene glycol and organic acid are successfully separated from fermentation liquor by reduced pressure distillation on the premise of adjusting the concentration of glycerol in the concentrated fermentation liquor to 15% -20%. And rectifying and separating the obtained mixture to respectively recover the organic acid and the 1, 3-propylene glycol. However, since the boiling point and polarity of the organic acid are close to those of 1, 3-propanediol (e.g., 164 ℃ for butyric acid and 210 ℃ for 1, 3-propanediol), the complete separation requires the use of a rectifying tower and is carried out under the condition of high reflux ratio, thereby increasing the equipment investment cost and energy consumption. In addition, in the rectification separation process of the organic acid and the 1, 3-propylene glycol, a considerable part of the organic acid (10% -20%) reacts with the 1, 3-propylene glycol to generate propylene glycol ester impurities, so that the yield of the organic acid is reduced, and the final purity of the 1, 3-propylene glycol is also seriously influenced.
CN03133584.5 proposes adding alcohols or ketones with a certain volume ratio into the concentrated fermentation liquor, so that nucleic acid, protein and partial salt in the fermentation liquor can be precipitated and separated, thereby solving the serious salting-out phenomenon occurring in the later stage of reduced pressure distillation/rectification to a certain extent and reducing the influence of salt crystallization on the evaporation efficiency of 1, 3-propanediol. However, the process does not take into account the recovery of organic acids. In fact, the organic acid salt has high solubility in alcohols such as methanol and ethanol, and most of the organic acid salt is dissolved in the alcohols after the fermentation broth is subjected to alcohol precipitation and salting-out treatment, and is separated out again in the subsequent propylene glycol distillation process to become solid waste. In summary, no separation and purification method for simultaneously and efficiently extracting dihydric alcohol and organic acid byproducts from microbial fermentation broth has been reported at present.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a method for simultaneously extracting a diol and an organic acid ester from a microbial fermentation broth, which can simultaneously and efficiently extract the diol and the organic acid ester.
In order to achieve the above objects, the present invention provides a method for simultaneously extracting dihydric alcohol and an organic acid ester from a microbial fermentation broth, comprising the steps of:
s1) separating the bacteria-carrying fermentation liquor which contains dihydric alcohol and organic acid as main fermentation products by an ultrafiltration membrane, removing thalli and protein, and obtaining the fermentation liquor treated by the ultrafiltration membrane;
s2) mixing the fermentation liquor treated by the ultrafiltration membrane with glycerol, adjusting the pH value to be alkaline, and carrying out reduced pressure distillation on the system to remove water to obtain concentrated fermentation liquor;
s3) mixing the concentrated fermentation liquor with the monohydric alcohol compound, adjusting the pH value to 2-3 by adopting inorganic acid, and filtering to remove precipitated salts to obtain filtrate;
s4) mixing the filtrate obtained in S3) with a catalyst, carrying out esterification reaction on organic acid and a monohydric alcohol compound to generate organic acid ester, and then separating the monohydric alcohol compound and the organic acid ester through reduced pressure distillation;
s5) adjusting the pH value of the distillation residue obtained in the step S4) to be neutral, and carrying out rectification separation to obtain the dihydric alcohol.
In a preferred embodiment of the present invention, the diol is one or more selected from the group consisting of 1, 3-propanediol, 1, 2-propanediol, 2, 3-butanediol, 1, 4-butanediol, and isoprene glycol.
Preferably, the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, succinic acid, lactic acid and pyruvic acid.
In the present invention, the organic acid is present in the form of an organic acid salt, preferably a sodium salt, potassium salt, calcium salt or magnesium salt.
In some embodiments of the invention, the bacteria-bearing fermentation broth comprises 1, 3-propanediol or 2, 3-butanediol as a main product and acetate and butyrate as main byproducts.
Preferably, the ultrafiltration membrane has a cut-off pore size of 1-10kDa, more preferably 6 kDa.
In the preferred embodiment of the present invention, in step S2), the amount of glycerol is 3 wt% to 10 wt% of the fermentation broth, that is, after the glycerol is added, the concentration of glycerol in the fermentation broth is 3 wt% to 10 wt%, and the preferred concentration of glycerol is not less than 4%.
The glycerol is not particularly limited in the present invention, and may be generally commercially available, and preferably, the concentration of the glycerol is not less than 50%, more preferably not less than 80%.
The system pH was then adjusted to basic.
Preferably, the pH is adjusted by NaOH or KOH solution.
The concentration of the NaOH solution or the KOH solution is preferably 30 to 50 percent.
According to the invention, the pH value is preferably adjusted to be more than 8, and more preferably, the pH value is adjusted to be 11-12.
Then, reduced pressure distillation is carried out to remove water.
The temperature of the reduced pressure distillation is preferably 80-120 ℃, and the vacuum degree is preferably 50-80 mbar.
After the reduced pressure distillation, the water content in the fermentation broth is preferably 5% or less, more preferably 1% or less.
And then adding a monohydric alcohol compound into the concentrated fermentation liquor, then adding an inorganic acid to adjust the pH value to 2-3, and filtering to remove precipitated salts to obtain a filtrate.
The monohydric alcohol compound is preferably methanol, ethanol, n-propanol or n-butanol, more preferably methanol or ethanol.
The addition amount of the monohydric alcohol compound is preferably 1-3 times, more preferably 2 times, of the mass of the concentrated fermentation broth.
The inorganic acid is preferably concentrated hydrochloric acid, more preferably hydrochloric acid having a concentration of 37%. The above concentration refers to mass concentration.
The method for removing the precipitated salts by filtration in the present invention is not particularly limited, and may be a method known to those skilled in the art, including, but not limited to, plate-and-frame filtration and the like.
Then adding a catalyst into the obtained filtrate to carry out esterification reaction on the organic acid and the monohydric alcohol compound to generate organic acid ester.
The catalyst is preferably a homogeneous catalyst, or a strongly acidic cationic polymer heterogeneous catalyst.
The homogeneous catalyst is preferably sulfuric acid, p-toluenesulfonic acid or dodecylbenzenesulfonic acid.
The addition amount of the homogeneous catalyst is preferably 1-10% (w/w) of the filtrate.
The strongly acidic cationic polymer heterogeneous catalyst is preferably Amberlyst 15, Amberlyst 16, Amberlyst 35 or Amberlyst 36.
The addition amount of the heterogeneous catalyst is preferably 5% to 20% (w/w) of the filtrate.
The catalyst is further preferably Amberlyst 15. The amount added is preferably 10% (w/w) of the filtrate.
The invention uses the relatively mild heterogeneous catalyst Amberlyst 15 to avoid the generation of the dihydric alcohol ester to the maximum extent, and is beneficial to the realization of the coproduction process of the dihydric alcohol and the organic acid ester.
The temperature of the esterification reaction is preferably reflux, and the time is preferably 1 to 3 hours, and more preferably 2 hours.
The organic acid ester is organic acid methyl ester (methanol), ethyl ester (ethanol), propyl ester (n-propanol) or butyl ester (n-butanol) according to the difference of the monohydric alcohol compound used in the previous step.
The invention separates out monohydric alcohol compound and generated organic acid ester by vacuum distillation.
The temperature for separating the monohydric alcohol compound and the organic acid ester through reduced pressure distillation is preferably 60-120 ℃, and the vacuum degree is 50-300 mbar.
And finally, adjusting the pH value of the distillation residue obtained in the step S4) to be neutral, and performing rectification separation to obtain the dihydric alcohol.
According to the invention, preferably, the pH value of distillation residue is adjusted to be neutral by adopting NaOH aqueous solution.
In the present invention, the concentration of the NaOH aqueous solution is preferably 1% to 5%, more preferably 2%. The above concentration is a mass concentration.
The amount of the NaOH aqueous solution added is preferably 20% to 100% (w/w), more preferably 50% (w/w), of the distillation residue.
In the invention, preferably, the NaOH aqueous solution is added, and simultaneously, the activated carbon is added, and the system is heated and stirred for carrying out the decoloring treatment.
The activated carbon is not particularly limited in the present invention, and may be generally commercially available. Preferably 10 to 200 mesh active carbon, more preferably 200 mesh active carbon.
The amount of the activated carbon added is preferably 1% to 3% (w/w), more preferably 1% (w/w), of the distillation residue.
And (4) filtering to remove the active carbon after decoloring treatment.
The system is then dehydrated.
The dehydration in the present invention is not particularly limited, and is preferably the same as the dehydration in step S2).
The number of theoretical plates of the rectifying tower used for the rectifying separation is preferably 8-50, and a rectifying tower with the number of the theoretical plates of 8 is more preferably used.
The temperature of the rectification separation heating is preferably 120-180 ℃, and more preferably 140 ℃; the reflux ratio is preferably 0 to 3, and more preferably 3; the vacuum degree is preferably 1-20 mbar, and more preferably 5 mbar.
If the final product is used as a flavor modifier or a humectant for food or cosmetics, the rectification separation can also be directly carried out by using single-stage reduced pressure distillation, preferably under the conditions of 140-145 ℃ and 10-20 mbar of vacuum degree.
The remaining glycerol in the system can be directly reused for fermentation production, or reused for the above step S2), or used for producing refined glycerol.
The flow chart of the above process is shown in fig. 1. Wherein, 1 is a fermentation tank, 2 is an ultrafiltration membrane, 3 is a single-effect evaporator, 4 is an esterification reaction kettle, 5 is a plate-and-frame filter, 6 is a neutralization and decoloration kettle, 7 is a microfiltration membrane, and 8 is a rectifying tower.
The monohydric alcohol compound added in the invention not only serves as a precipitator of inorganic salt in the fermentation liquor, but also serves as an esterification reactant to convert organic acid in the fermentation liquor into organic acid ester with higher added value. After the organic acid is converted into corresponding esters, the hydrophilicity and the boiling point are both obviously reduced, the organic acid ester and the dihydric alcohol can be completely separated through simple single-stage distillation, the generation of impurities of the dihydric alcohol ester is greatly reduced, the co-production of the high-purity dihydric alcohol and the organic acid ester is favorably realized, and the cost for producing the dihydric alcohol by a microbial fermentation method is greatly reduced.
The invention also provides another method for simultaneously extracting dihydric alcohol and organic acid ester from microbial fermentation liquor, which comprises the following steps:
s1) separating the bacteria-carrying fermentation liquor which contains dihydric alcohol and organic acid as main fermentation products by an ultrafiltration membrane, removing thalli and protein, and obtaining the fermentation liquor treated by the ultrafiltration membrane;
s2) mixing the fermentation liquor treated by the ultrafiltration membrane with glycerol, adjusting the pH value to be alkaline, and carrying out reduced pressure distillation on the system to remove water to obtain concentrated fermentation liquor;
s3') carrying out reduced pressure distillation on the concentrated fermentation liquor to separate out dihydric alcohol and a small amount of glycerol;
s4 ') mixing the residues obtained after the distillation of S3') with monohydric alcohol compounds, adjusting the pH value to 2-3 by adopting inorganic acid, and filtering to remove precipitated salts to obtain filtrate;
s5 ') mixing the filtrate obtained in S4') with a catalyst to carry out esterification reaction between organic acid and monohydric alcohol compound to generate organic acid ester, and then separating the monohydric alcohol compound and the organic acid ester by reduced pressure distillation.
The above steps S1), S2) are the same as above, and will not be described herein again.
In the above step S3'), the distillation under reduced pressure is preferably short path distillation. This step allows the separation of most of the glycols and a small amount of glycerin.
The proportion of the diol to be removed is preferably 90% to 95%, and the proportion of glycerin is preferably 10% to 20%.
Preferably, the short-path distillation system comprises a built-in condenser and a scraper, and the residual glycerin is driven by the scraper to uniformly disperse the salt precipitated in the evaporation process and is discharged from the short-path distillation system in the form of heavy components. The preferred conditions of the short-path distillation are that the heating surface temperature is 100-150 ℃, and more preferably 125 ℃; the temperature of a condensing surface is 10-20 ℃, and 20 ℃ is more preferable; the vacuum degree is 1-5 mbar, and 1mbar is more preferable. The light component obtained by short-path distillation contains a large amount of dihydric alcohol and a small amount of glycerin, does not contain organic acid residue, is colorless and tasteless, and can be directly used for cosmetics and foods, or the dihydric alcohol and the glycerin are separated by rectification separation according to the step S5) to respectively obtain the high-purity dihydric alcohol and the high-purity glycerin.
And (3) obtaining a heavy component containing most of glycerol and all salts in the fermentation liquor through short-path distillation, mixing the distilled residue with a monohydric alcohol compound, adjusting the pH value to 2-3 by adopting an inorganic acid, and filtering to remove the precipitated salts to obtain a filtrate.
Mixing the obtained filtrate with a catalyst to perform esterification reaction on the organic acid and the monohydric alcohol compound to generate organic acid ester, and then separating the monohydric alcohol compound and the organic acid ester by reduced pressure distillation.
The operations of the salting out, esterification and vacuum distillation are the same as those of the steps S3), S4) and S5), which are not repeated herein.
The inorganic acid is preferably one or more of concentrated hydrochloric acid, concentrated sulfuric acid and phosphoric acid.
After the neutralization by adding the aqueous NaOH solution to the remaining glycerin, the aqueous glycerin solution may be directly reused for the fermentation production or reused in the above step S2).
In the present invention, the concentration of the NaOH aqueous solution is preferably 1% to 5%, more preferably 2%. The above concentration is a mass concentration.
The amount of the NaOH aqueous solution added is preferably 20% to 100% (w/w), more preferably 50% (w/w), of the distillation residue.
The flow chart of the above process is shown in fig. 2. Wherein, 1 is a fermentation tank, 2 is an ultrafiltration membrane, 3 is a single-effect evaporator, 4 is short-range distillation, 5 is a rectifying tower, 6 is a plate-frame filter, and 7 is an esterification reaction kettle.
Compared with the prior art, the invention provides a method for simultaneously extracting dihydric alcohol and organic acid ester from microbial fermentation broth, which comprises the following steps: s1) separating the bacteria-carrying fermentation liquor which contains dihydric alcohol and organic acid as main fermentation products by an ultrafiltration membrane, removing thalli and protein, and obtaining the fermentation liquor treated by the ultrafiltration membrane; s2) mixing the fermentation liquor treated by the ultrafiltration membrane with glycerol, adjusting the pH value to be alkaline, and carrying out reduced pressure distillation on the system to remove water to obtain concentrated fermentation liquor; s3) mixing the concentrated fermentation liquor with the monohydric alcohol compound, adjusting the pH value to 2-3 by adopting inorganic acid, and filtering to remove precipitated salts to obtain filtrate; s4) mixing the filtrate obtained in S3) with a catalyst, carrying out esterification reaction on organic acid and a monohydric alcohol compound to generate organic acid ester, and then separating the monohydric alcohol compound and the organic acid ester through reduced pressure distillation; s5) adjusting the pH value of the distillation residue obtained in the step S4) to be neutral, and carrying out rectification separation to obtain the dihydric alcohol.
The invention provides an innovative separation method capable of simultaneously and efficiently extracting dihydric alcohol and organic acid ester, aiming at the problem that organic acid byproducts are difficult to recover in the subsequent purification and separation process of the dihydric alcohol produced by a microbial fermentation method, so that the productivity and the raw material utilization rate of the whole fermentation production process are greatly improved, and the cost of producing the dihydric alcohol by the microbial fermentation method is indirectly reduced. The invention skillfully combines the alcohol precipitation salting-out effect of alcohol on inorganic salt in fermentation liquor and the esterification reaction activity with organic acid in the fermentation liquor, and converts the organic acid into organic acid ester (such as organic acid methyl ester, ethyl ester, propyl ester and butyl ester) with higher added value and lower boiling point while removing the inorganic salt in the fermentation liquor. After the organic acid is converted into the corresponding organic acid ester, the organic acid can be completely separated from the dihydric alcohol through simple single-stage reduced pressure distillation. Meanwhile, the organic acid ester and the dihydric alcohol do not generate side reaction in the distillation process, thereby greatly reducing the generation of the dihydric alcohol ester impurities and being more beneficial to the preparation of the high-purity dihydric alcohol.
The invention also provides a method for simultaneously extracting dihydric alcohol and organic acid ester from microbial fermentation liquor, which comprises the following steps:
s1) separating the bacteria-carrying fermentation liquor which contains dihydric alcohol and organic acid as main fermentation products by an ultrafiltration membrane, removing thalli and protein, and obtaining the fermentation liquor treated by the ultrafiltration membrane;
s2) mixing the fermentation liquor treated by the ultrafiltration membrane with glycerol, adjusting the pH value to be alkaline, and carrying out reduced pressure distillation on the system to remove water to obtain concentrated fermentation liquor;
s3') carrying out reduced pressure distillation on the concentrated fermentation liquor, and separating out partial dihydric alcohol and glycerol;
s4 ') mixing the residues obtained after the distillation of S3') with monohydric alcohol compounds, adjusting the pH value to 2-3 by adopting inorganic acid, and filtering to remove precipitated salts to obtain filtrate;
s5 ') mixing the filtrate obtained in S4') with a catalyst to perform an esterification reaction between an organic acid and a monohydric alcohol compound to produce an organic acid ester, and then separating the monohydric alcohol compound and the organic acid ester by distillation under reduced pressure.
The method comprises distilling under reduced pressure to remove most of dihydric alcohol and small amount of glycerol, wherein the obtained dihydric alcohol and glycerol contain no organic acid residue, are colorless and odorless, and can be directly used in cosmetics and food. Then alcohol precipitation salting-out action of alcohol on inorganic salt in fermentation liquor and esterification reaction activity of alcohol and organic acid in the fermentation liquor are utilized, alcohol compounds and organic acid esters can be separated through simple reduced pressure distillation, most of dihydric alcohol is removed in advance, so that the type of inorganic acid for subsequently adjusting the pH value does not need to be particularly limited, the inorganic acid can be used generally, the productivity and the raw material utilization rate of the whole fermentation production process are greatly improved, and the cost for producing the dihydric alcohol by a microbial fermentation method is indirectly reduced.
Drawings
FIG. 1 is a process flow chart of the present invention for simultaneously extracting dihydric alcohol and organic acid ester from a microbial fermentation broth;
FIG. 2 is a process flow chart of the present invention for simultaneously extracting dihydric alcohol and organic acid ester from a microbial fermentation broth.
Detailed Description
In order to further illustrate the present invention, the following examples are provided to describe the method for simultaneously extracting the dihydric alcohol and the organic acid ester from the microbial fermentation broth.
The fermentation broths used in examples 1-3, comparative example 1, and comparative example 2 below were obtained from Clostridium pasteurianum (Clostridium pasteurianum) by batch fed-batch glycerol fermentation to produce 1, 3-propanediol. During the fermentation process, 5M NaOH aqueous solution is used for controlling the pH, so that the organic acids (acetic acid and butyric acid) in the fermentation liquor mainly exist in a sodium salt form. After fermentation is finished, the fermentation liquor contains 0.8-1.0% of thalli and protein and 6-10% of 1, 3-propylene glycol; 0.5% -5% of glycerin; 1.0 to 2.0 percent of acetic acid, 0.4 to 1.2 percent of butyric acid and 0.5 to 0.7 percent of inorganic salt. The fermentation broth after removal of the bacteria and proteins by ultrafiltration was used as the starting material for the purification experiments of examples 1-3.
The fermentation broth used in example 4 was formulated from the final broth ingredients reported in the literature from Laoultella terrigena via batch fed-batch, crude glycerol fermentation to produce 2, 3-butanediol. The pH value of the prepared artificial fermentation liquor is adjusted to 11 by 50 percent NaOH aqueous solution. The synthetic fermentation broth contains 9.2% of 2, 3-butanediol, 9.5% of glycerol, 0.95% of ethanol, 1.1% of acetone, 0.88% of acetic acid, and 0.7% of inorganic salt as a component of a culture medium. The content change of each component in the purification process is determined by high performance liquid chromatography detection, and the data are detailed in tables 1-4.
Example 1:
1. crude glycerol (containing 80% glycerol) was added to the fermentation broth after the treatment with the 6kDa ultrafiltration membrane so that the glycerol content in the fermentation broth became 4%, to obtain 4162g of a mixture of the fermentation broth and glycerol. The mixed fermentation broth is put into a rotary evaporation bottle, and is heated in an oil bath at 80 ℃ to distill out 85 percent of water under the condition of a vacuum degree of 200 mbar. The heating temperature was then increased to 120 ℃ and the vacuum was reduced to 50mbar and the remaining water was distilled off. Finally, 3610g of water is separated and collected, and 552g of the residual concentrated fermentation liquor is obtained. The content of 1, 3-propanediol is increased from 7.14% to 51.90%. The yield was 96.5%.
2. To the above concentrated fermentation solution was added 2.5 times by mass of methanol, and after dispersion by stirring, 37% HCl was added to adjust the pH to 2, and the precipitated salt was removed by plate-and-frame filtration to obtain 1844g of a filtrate. The content of 1, 3-propanediol was 13.60%, and the yield was 84.4%.
3. 10% (w/w) Amberlyst 15 resin catalyst (Dow chemical) was added to the above filtrate, and the mixture was heated in an oil bath at 70 ℃ under reflux for 2 hours to cause esterification of the organic acid in the filtrate with methanol. After the reaction is finished, the content of the 1, 3-propanediol is reduced from 13.60 percent to 13.54 percent, and the content of the glycerol is basically not changed. Thus, the esterification reaction between the organic acid and the 1, 3-propylene glycol and the glycerol is less. On the other hand, the content of methyl acetate after the reaction was 4.52%, and the content of methyl butyrate was 1.82%. The methyl ester conversion of acetic acid and butyric acid was 99.5% and 99.2%, respectively.
4. And (3) filtering the esterification crude product to remove catalyst resin, and then putting the esterification crude product into a rotary evaporator, heating the esterification crude product in an oil bath at 60 ℃ and distilling the esterification crude product to recover methanol and organic acid ester under the condition of a vacuum degree of 200 mbar. The final separation yielded 1344g of a methanol solution with a methyl acetate content of 5.47% and a methyl butyrate content of 2.57%. The final yield of methyl acetate was 86.5% and the final yield of methyl butyrate was 86.4% (table 1).
5. To the above distillation residue was added 250g of a 2% aqueous solution of sodium hydroxide and at the same time 1% (w/w) of 200 mesh activated carbon powder, and the mixture was heated and stirred at 60 ℃ for 2 hours. The sodium hydroxide added in this step serves to neutralize small amounts of residual hydrochloric acid and unreacted organic acids and to hydrolyze small amounts of propylene glycol esters formed in the esterification reaction to free propylene glycol and sodium organic acids. The activated carbon powder is used for decoloring and deodorizing products. Filtering with plate frame to remove active carbon powder, adding the filtrate into rotary evaporation flask, heating in 120 deg.C oil bath, distilling off all water under vacuum degree of 50mbar, heating to 145 deg.C, reducing vacuum degree to 20mbar, and collecting 1, 3-propylene glycol fraction. 240g of fraction containing 96% of 1, 3-propanediol, 3% of glycerol and 77.6% of 1, 3-propanediol are finally separated and collected. The distillation residue obtained is 215g, contains a large amount of glycerol (> 70%) and a small amount of 1, 3-propanediol (10%), contains a small amount of sodium organic acid, and can be directly used for fermentation production of the next batch or used for adjusting the concentration of glycerol in fermentation liquor of the next batch.
The following table 1 shows the content changes of the components in the purification process of this example:
TABLE 1
Example 2:
1. crude glycerol (containing 80% glycerol) was added to the fermentation broth treated with the 6kDa ultrafiltration membrane so that the glycerol content in the fermentation broth became 7%, whereby 2639g of the fermentation broth-glycerol mixture was obtained. The fermentation broth was placed in a rotary evaporator flask and heated in an oil bath at 80 ℃ under a vacuum of 200mbar to distill off 85% of the water. The heating temperature was then increased to 120 ℃ and the vacuum was reduced to 50mbar and the remaining water was distilled off. Finally, 2239g of water is separated and collected, and 400g of concentrated fermentation liquor is remained. The content of 1, 3-propanediol is increased from 6.9 percent to 43.70 percent. The yield was 96%.
2. Adding 2 times of ethanol by mass into the concentrated fermentation liquor, stirring and dispersing, adding 37% HCl to adjust the pH to 2, and filtering by a plate frame to remove the precipitated salt to obtain 1100g of filtrate. The content of 1, 3-propanediol was 14.49%, the yield was 87.6%.
3. 10% (w/w) Amberlyst 15 resin catalyst (Dow chemical) was added to the above filtrate, and the mixture was heated and refluxed in an oil bath at 80 ℃ for 2 hours to cause esterification reaction between the organic acid in the filtrate and ethanol. After the reaction is finished, the content of the 1, 3-propanediol is reduced from 14.49 percent to 13.69 percent, and the content of the glycerol is basically not changed. Thus, the esterification reaction between the organic acid and the 1, 3-propylene glycol and the glycerin is less. On the other hand, the content of ethyl acetate after the reaction was 4.94%, and the content of ethyl butyrate was 1.89%. The ethyl acetate conversion of acetic acid and butyric acid was 94% and 93%, respectively.
4. And filtering the esterification crude product to remove catalyst resin, and then putting the esterification crude product into a rotary evaporator, heating the esterification crude product in an oil bath at 70 ℃ under the condition of a vacuum degree of 200mbar, and distilling and recovering ethanol and organic acid ester. 747g of ethanol solution with a content of ethyl acetate of 6.27% and a content of ethyl butyrate of 2.70% are finally obtained by separation. The final yield of ethyl acetate was 76.8% and the final yield of ethyl butyrate was 75.4% (table 2).
5. To the distillation residue was added 180g of a 2% aqueous solution of sodium hydroxide together with 1% (w/w) of 200 mesh activated carbon powder, and the mixture was heated and stirred at 60 ℃ for 2 hours. The sodium hydroxide added in this step serves to neutralize small amounts of residual hydrochloric acid and unreacted organic acids and to hydrolyze small amounts of propylene glycol esters formed in the esterification reaction to free propylene glycol and sodium organic acids. The activated carbon powder is used for decoloring and deodorizing products. Filtering with plate frame to remove active carbon powder, adding the filtrate into rotary evaporation flask, heating in 120 deg.C oil bath, distilling off all water under vacuum degree of 50mbar, heating to 145 deg.C, reducing vacuum degree to 20mbar, and collecting 1, 3-propylene glycol fraction. 152g of fraction containing 97.37% of 1, 3-propanediol, 2.23% of glycerol and 81.32% of 1, 3-propanediol are finally separated and collected. The distillation residue obtained in the previous step is 201g, contains a large amount of glycerol (> 76%) and a small amount of 1, 3-propanediol (5.5%), contains a small amount of sodium organic acid, and can be directly used for fermentation production of the next batch or used for adjusting the concentration of glycerol in the fermentation liquor of the next batch.
Table 2 shows the content change of each component in the purification process of this example:
TABLE 2
Example 3
1. Adding crude glycerol (containing 80% of glycerol) into the fermentation liquor treated by the 6kDa ultrafiltration membrane to ensure that the content of the glycerol in the fermentation liquor is 10%, and adding 50% NaOH aqueous solution to adjust the pH value to 11.4 to obtain 10kg of a mixture of the fermentation liquor and the glycerol. The fermentation broth was placed in a rectification column (internal diameter 50mm, theoretical plate number 8) and 85% of the water was distilled off by heating at 80 ℃ under a vacuum of 200 mbar. The heating temperature was then increased to 120 ℃ and the vacuum was reduced to 50mbar and the remaining water was distilled off. 7776g of water is finally separated and collected, and 2224g of the residual concentrated fermentation liquor is obtained. The content of 1, 3-propanediol is increased from 7.5 percent to 34 percent. The yield is close to 100%.
2. Subjecting the concentrated fermentation broth to short path distillation (volume 14L, inner diameter 75mm, height 165mm, heating area 0.16m2Containing built-in scraper and condenser), adjusting the temperature of an evaporation surface to be 125 ℃, the temperature of a condensation surface to be 20 ℃, the vacuum degree to be 1mbar, the speed of the scraper to be 200rpm and the flow rate to be 10-15mL/min, and finally separating to obtain 1135g of fraction. The fraction contained 64% of 1, 3-propanediol, 35.3% of glycerol and 96.9% of 1, 3-propanediol. The fraction contains almost no organic acid or propylene glycol ester impurity residue, and can be directly applied in cosmetics or food. In the short-path distillation process, as most of 1, 3-propanediol and part of glycerin are evaporated, salt in the fermentation liquor is gradually separated out and is dispersed by the residual glycerin to be taken out of the short-path distillation equipment. 1089g of glycerol/salt mixed distillation residue is finally obtained.
3. Adding 1.5 times of ethanol into the short-path distillation residue, stirring and dispersing, adding 96% sulfuric acid to adjust the pH value to 0-1, and filtering by a plate frame to remove the precipitated salt to obtain 2425g of filtrate. Wherein the contents of glycerol, acetic acid and butyric acid are 19.2%, 5.6% and 3%, respectively.
4. And directly stirring and heating the filtrate to reflux for 2 hours to ensure that the organic acid in the filtrate and the ethanol have esterification reaction. After the reaction is finished, the contents of 1, 3-propanediol and glycerol are basically not changed. Thus, the esterification reaction between the organic acid and the 1, 3-propylene glycol and the glycerin is less. On the other hand, the content of ethyl acetate after the reaction was 7.79%, and the content of ethyl butyrate was 3.58%. The ethyl acetate conversion of acetic acid and butyric acid was 95% and 92%, respectively.
5. And (3) putting the esterified crude product into a rotary evaporator, heating in an oil bath at 70 ℃, and distilling and recovering ethanol and organic acid ester under the condition of vacuum degree of 200 mbar. The final separation yielded 1844g of an ethanol solution containing 10.2% of ethyl acetate and 4.61% of ethyl butyrate. The final yield of ethyl acetate was 80% and the final yield of ethyl butyrate was 81% (table 3). After recovery of ethanol, 580g of distillation residue were left, containing 80% glycerol, 4.6% 1, 3-propanediol and traces of unreacted organic acid. To the distillation residue was added 300g of a 2% aqueous solution of sodium hydroxide to neutralize glycerol. The neutralized glycerin aqueous solution can be directly used for the next fermentation production or used for adjusting the glycerin concentration in the fermentation liquor of the next batch.
Table 3 shows the content change of each component during the purification process of this example:
TABLE 3
Example 4:
1. 2100g of the prepared 2, 3-butanediol fermentation liquor is put into a rotary evaporation bottle, and most of water and all ethanol and acetone are removed under the conditions of oil bath heating at 80 ℃ and a vacuum degree of 200 mbar. The heating temperature was then increased to 120 ℃ and the vacuum was reduced to 50mbar and the remaining water was distilled off. Finally, 1621g of distillate was collected by separation, and 479g of the remaining concentrated fermentation broth was collected. The content of 2, 3-butanediol is increased from 9.2% to 39%. The yield was 96.6%.
2. 400g of concentrated fermentation broth are subjected to short path distillation (volume 14L, inner diameter 75mm, height 165mm, heating area 0.16m2Containing built-in scraper and condenser), regulating evaporation surface temperature to 125 deg.C, condensation surface temperature to 20 deg.C, vacuum degree to 1mbar, scraper speed to 200rpm, flow rate to 10-15mL/min, and separating to obtain final product220g of fraction. The fraction contained 69.5% of 2, 3-butanediol, 31% of glycerol and 94.7% of 2, 3-butanediol. The fraction does not contain any organic acid or propylene glycol ester impurity residue, and can be directly applied in cosmetics or food. In the short-path distillation process, as most of 2, 3-butanediol and part of glycerin are evaporated, salt in the fermentation liquor is gradually separated out and is dispersed by the residual glycerin to be taken out of the short-path distillation equipment. Finally, 180g of glycerin/salt mixed distillation residue is obtained.
3. Adding 1.5 times of ethanol into the short-path distillation residue, stirring and dispersing, adding 96% sulfuric acid to adjust the pH value to 0-1, and filtering with a plate frame to remove the precipitated salt to obtain 390g of filtrate. Wherein the glycerol and acetic acid contents were 23.6% and 3.6%, respectively.
4. And directly stirring and heating the filtrate to reflux for 2 hours to ensure that acetic acid in the filtrate and ethanol have esterification reaction. After the reaction is finished, the contents of the 2, 3-butanediol and the glycerol are basically not changed. Thus, the esterification reaction between acetic acid and 2, 3-butanediol and glycerin is less. On the other hand, the ethyl acetate content after the reaction was 5.1%, and the ethyl acetate conversion rate of acetic acid was 96.6%.
5. And (3) putting the crude esterification product into a rotary evaporator, heating in oil bath at 70 ℃, and distilling and recovering ethanol and ethyl acetate under the condition of vacuum degree of 200 mbar. The final isolation gave 257g of ethanol solution, in which the ethyl acetate content was 7.64% and the final yield of ethyl acetate was 89.2% (Table 4). After recovery of the ethanol, 133g of distillation residue remained, containing 73.7% of glycerol, 2.5% of 2, 3-butanediol, and traces of unreacted organic acid remained. 100g of a 2% aqueous solution of sodium hydroxide was added to the distillation residue to neutralize glycerol. The neutralized glycerol aqueous solution can be directly used for the next fermentation production or used for adjusting the concentration of glycerol in the fermentation liquor of the next batch.
Table 4 shows the content change of each component in the purification process of this example:
TABLE 4
Table 5 is a comparison of the yield of glycol and organic acid ester in the above examples:
TABLE 5
Comparative example 1
To investigate the influence of the kind of catalyst on the selectivity of organic acid esterification, the following comparative example was carried out with respect to scheme 1
1. Crude glycerol (80%) was added to the fermentation broth treated with the 6kDa ultrafiltration membrane so that the glycerol content in the fermentation broth became 4%, to obtain 1000g of the fermentation broth. The fermentation broth was placed in a rotary evaporator flask and first heated in an oil bath at 80 ℃ under a vacuum of 200mbar to distill off 85% of the water. The heating temperature was then raised to 120 ℃ and the vacuum was reduced to 50mbar, the remaining water being distilled off. Finally, 837g of water was collected by separation, and 163g of the concentrated fermentation broth remained. The content of 1, 3-propanediol is increased from 7.5% to 45.54%. The yield was 95%.
2. Adding 2.5 times of methanol into the concentrated fermentation liquor, stirring and dispersing, adding 96% sulfuric acid to adjust the pH to 0.5, and filtering with a plate frame to remove the precipitated salt to obtain 502g of filtrate. The content of 1, 3-propanediol was 13.34%, and the yield was 89.3%.
3. And directly stirring and heating the filtrate to reflux for 2 hours to ensure that the organic acid in the filtrate and the methanol have esterification reaction. After the reaction was completed, the content of methyl acetate was measured to be 3.12%, and the content of methyl butyrate was measured to be 1.06%. The methyl ester conversion of acetic acid and butyric acid was 75% and 46%, respectively. On the other hand, the 1, 3-propanediol content was reduced from 13.34% to 10.76%, indicating that 18% of the 1, 3-propanediol was esterified with an organic acid.
4. And (3) putting the crude esterification product into a rotary evaporator, heating in an oil bath at 60 ℃, and distilling to recover the methanol and the organic acid ester under the condition of a vacuum degree of 200 mbar. Finally, 387g of a methanol solution were obtained, the methyl acetate content of which was 3.89% and the methyl butyrate content of which was 1.30%. The final yield of methyl acetate was 68.4% and the final yield of methyl butyrate was 43.4%.
5. To the above distillation residue was added 100g of a 4% aqueous solution of sodium hydroxide and at the same time 1% (w/w) of 200 mesh activated carbon powder, and the mixture was heated and stirred at 60 ℃ for 2 hours. The sodium hydroxide added in this step serves to neutralize the remaining sulfuric acid and unreacted organic acids and to hydrolyze the propylene glycol organic acid esters formed in the esterification reaction to free propylene glycol and sodium organic acid. The activated carbon powder is used for decoloring and deodorizing products. Filtering with plate frame to remove active carbon powder, adding the filtrate into rotary evaporation bottle, heating in 120 deg.C oil bath, distilling to remove all water under vacuum degree of 50mbar, heating to 145 deg.C, reducing vacuum degree to 20mbar, and collecting 1, 3-propylene glycol fraction. And finally, separating and collecting 50g of fraction containing 94% of 1, 3-propylene glycol and 2% of glycerol, wherein the rest impurities are mainly propylene glycol organic acid ester. The final yield of 1, 3-propanediol was 62.6%.
The above comparative example illustrates that the esterification selectivity of the organic acid during purification directly affects the yield of the organic acid ester and the final purity of the diol. The esterification reaction should occur as much as possible between the organic acid and the monohydric alcohol. If excessive organic acid and dihydric alcohol are subjected to esterification reaction, the generated dihydric alcohol ester not only simultaneously reduces the yield of organic acid ester and the yield of the dihydric alcohol, but also can not be completely separated by rectification because the boiling point of the dihydric alcohol ester is very close to that of the dihydric alcohol, and only can remove impurities of the dihydric alcohol ester by adding an alkali solution for hydrolysis reaction. The higher the content of glycol ester impurities, the greater the amount of base required for hydrolysis, increasing the production cost. If the glycol ester cannot be completely hydrolyzed, the final product will have glycol ester impurities, which seriously affect the final purity of the glycol. The type of catalyst is one of the important factors affecting the selectivity of the esterification of organic acids. In the system containing the dihydric alcohol, the sulfuric acid is used as a catalyst, so that the generation of the dihydric alcohol ester is obviously increased, and the preparation of the high-purity dihydric alcohol is not facilitated.
Comparative example 2
To investigate the effect of pH range on the purity of the diol product obtained by short path distillation, a comparative experiment was performed in accordance with scheme 2
1. Adding crude glycerol (80%) into the fermentation liquor treated by the 6kDa ultrafiltration membrane to ensure that the glycerol content in the fermentation liquor is 10%, and simultaneously adding 50% NaOH aqueous solution to adjust the pH value to 8.0 to obtain 1200g of fermentation liquor. The fermentation broth was placed in a rotary evaporator flask and heated in an oil bath at 80 ℃ under a vacuum of 200mbar to distill off 85% of the water. The heating temperature was then increased to 120 ℃ and the vacuum was reduced to 50mbar and the remaining water was distilled off. Finally, 937g of water is separated and collected, and 236g of the residual concentrated fermentation liquor is obtained. The content of 1, 3-propanediol is increased from 6.25% to 30.1%. The yield was 94.7%.
2. Subjecting the concentrated fermentation broth to short path distillation (volume 14L, inner diameter 75mm, height 165mm, heating area 0.16m2Containing built-in scraper and condenser), the evaporation surface temperature is adjusted to 125 ℃, the condensation surface temperature is adjusted to 20 ℃, the vacuum degree is 1mbar, the scraper speed is 200rpm, the flow rate is 10-15mL/min, and finally 142g of fraction is obtained by separation. The fraction contained 49.1% of 1, 3-propanediol, 48.3% of glycerol, 1.3% of acetic acid, 0.56% of butyric acid and 93% of 1, 3-propanediol. The fraction contains a small amount of organic acid residues, cannot be directly used for foods or cosmetics, and needs to be subjected to deacidification treatment by a rectifying tower so as to meet the application requirements of products.
The above comparative examples illustrate:
1) the adjustment of the glycerol content and the pH value in the fermentation liquor is the key for determining the success or failure of the short-path distillation. Salt which is difficult to be fully suspended and separated out in the short-path distillation process when the content of glycerol is insufficient (< 10%); the pH must be adjusted to 11-12 to ensure that no organic acids are distilled off during the short path distillation, contaminating the light components.
2) After the dihydric alcohol and the organic acid are successfully separated by short-path distillation, the treatment of the mixture of the residual glycerin, the inorganic salt and the organic acid salt becomes more convenient. Because the trihydroxy structure of glycerol has larger steric hindrance, the esterification reaction activity of glycerol and organic acid is far lower than that of organic acid and monohydric alcohol. Therefore, after alcohol precipitation and desalination, concentrated sulfuric acid can be directly used as a pH regulator and a catalyst to efficiently convert organic acid into corresponding organic acid ester. In addition, the monohydric alcohol used for alcohol precipitation even is methanol, which does not affect the application of the dihydric alcohol in food, because the esterification reaction does not involve the participation of the dihydric alcohol.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (12)
1. A method for simultaneously extracting dihydric alcohol and organic acid ester from microbial fermentation liquor comprises the following steps:
s1) separating the bacteria-carrying fermentation liquor which contains dihydric alcohol and organic acid as main fermentation products by an ultrafiltration membrane, removing thalli and protein, and obtaining the fermentation liquor treated by the ultrafiltration membrane;
s2) mixing the fermentation liquor treated by the ultrafiltration membrane with glycerol, adjusting the pH value to be alkaline, and carrying out reduced pressure distillation on the system to remove water to obtain concentrated fermentation liquor;
s3) mixing the concentrated fermentation liquor with the monohydric alcohol compound, adjusting the pH value to 2-3 by adopting inorganic acid, and filtering to remove precipitated salts to obtain filtrate;
s4) mixing the filtrate obtained in the step S3) with a catalyst, carrying out esterification reaction on organic acid and monohydric alcohol compounds to generate organic acid esters, and then separating the monohydric alcohol compounds and the organic acid esters through reduced pressure distillation; the catalyst is selected from strong acid type cationic polymer heterogeneous catalysts;
s5) adjusting the pH value of the distillation residue obtained in the step S4) to be neutral, and carrying out rectification separation to obtain the dihydric alcohol.
2. The process according to claim 1, characterized in that the mineral acid is selected from concentrated hydrochloric acid.
3. The method as claimed in claim 1, wherein in the step S5), the number of theoretical plates of the rectifying tower used for rectification separation is 8-50; the temperature of the rectification separation heating is 120-180 ℃, the reflux ratio is 0-3, and the vacuum degree is 1-20 mbar.
4. The method of claim 1, wherein the strongly acidic cationic polymer heterogeneous catalyst is selected from Amberlyst 15, Amberlyst 16, Amberlyst 35 or Amberlyst 36.
5. A method for simultaneously extracting dihydric alcohol and organic acid ester from microbial fermentation liquor comprises the following steps:
s1) separating the bacteria-carrying fermentation liquor which contains dihydric alcohol and organic acid as main fermentation products by an ultrafiltration membrane, removing thalli and protein, and obtaining the fermentation liquor treated by the ultrafiltration membrane;
s2) mixing the fermentation liquor treated by the ultrafiltration membrane with glycerol, adjusting the pH to 11-12, and carrying out reduced pressure distillation on the system to remove water to obtain concentrated fermentation liquor;
s3') carrying out reduced pressure distillation on the concentrated fermentation liquor to separate out dihydric alcohol and a small amount of glycerol;
s4 ') mixing the distilled residue of S3') with a monohydric alcohol compound, adjusting the pH value to 2-3 by adopting inorganic acid, and filtering to remove precipitated salts to obtain filtrate;
s5 ') mixing the filtrate obtained in S4') with a catalyst to carry out esterification reaction between organic acid and monohydric alcohol compound to generate organic acid ester, and then separating the monohydric alcohol compound and the organic acid ester by reduced pressure distillation.
6. The method of claim 5, wherein the inorganic acid is selected from one or more of concentrated hydrochloric acid, concentrated sulfuric acid, and phosphoric acid.
7. The method according to claim 1 or 5, wherein the diol is selected from one or more of 1, 3-propanediol, 1, 2-propanediol, 2, 3-butanediol, 1, 4-butanediol, isoprene glycol;
the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, succinic acid, lactic acid and pyruvic acid.
8. The method according to claim 1 or 5, wherein in the step S2), the glycerol is used in an amount of 3-10 wt% of the fermentation broth; the temperature of the reduced pressure distillation is 80-120 ℃, and the vacuum degree is 50-80 mbar; after reduced pressure distillation, the water content in the fermentation liquor is less than or equal to 5 percent.
9. The method according to claim 1 or 5, wherein the monohydric alcohol compound is selected from methanol, ethanol, n-propanol or n-butanol;
the addition amount of the monohydric alcohol compound is 1-3 times of the mass of the concentrated fermentation liquor.
10. The process according to claim 5, characterized in that the catalyst is selected from homogeneous catalysts or from strongly acidic cationic polymer heterogeneous catalysts.
11. The process according to claim 10, characterized in that the homogeneous catalyst is selected from sulfuric acid, p-toluenesulfonic acid or dodecylbenzenesulfonic acid;
the strongly acidic cationic polymer heterogeneous catalyst is selected from Amberlyst 15, Amberlyst 16, Amberlyst 35 or Amberlyst 36.
12. The method according to claim 1 or 5, wherein the temperature for separating the monohydric alcohol compound and the organic acid ester by reduced pressure distillation is 60-120 ℃, and the vacuum degree is 50-300 mbar.
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