Method for separating and extracting acetic acid, propionic acid and butyric acid from anaerobic fermentation liquor
Through solid-liquid separation, extraction, esterification, distillation and decomposition extraction treatment, the problem of difficulty in separation of acetic acid, propionic acid and butyric acid in anaerobic fermentation broth is solved, and efficient and high-purity acid separation and high-value utilization of fermentation broth are achieved, with significant economic and environmental benefits.
Patent Information
- Application Number
- CN202510104087.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-22
- Publication Date
- 2025-05-06
AI Technical Summary
The existing separation technology is difficult to efficiently separate high-purity acetic acid, propionic acid and butyric acid from the anaerobic fermentation broth, and the process is complicated, the operation is difficult and cost-effective.
Acetic acid, propionic acid and butyric acid are gradually isolated and purified by solid-liquid separation, extraction, esterification, distillation and decomposition extraction treatments. Specific steps include: solid-liquid separation and removal of large particles suspended substances, extracting organic acids in the supernatant with organic solvents, converting the organic acid into an ester compound with ester, distillation and separation of the ester compound, and finally obtaining a high-purity acid through decomposition and extraction.
It has achieved efficient and high-purity separation and extraction of acetic acid, propionic acid and butyric acid in anaerobic fermentation broth, improved resource utilization, reduced waste emissions, and had significant economic and environmental benefits.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of wastewater resource utilization, and in particular to a method for separating and extracting acetic acid, propionic acid and butyric acid from anaerobic fermentation liquid. Background Art
[0002] With the acceleration of my country's urbanization process, the output of domestic waste has increased year by year, reaching an annual output of about 334 million tons, of which kitchen waste is close to 100 million tons. Kitchen waste has the dual attributes of resources and pollution, and its treatment has become an important issue in urban environmental management. Anaerobic fermentation, as a mature method for kitchen waste treatment, can directly produce volatile organic acids (VFAs) such as acetic acid, propionic acid, and butyric acid in the acid production stage. These acids not only have market value, but also have a wide range of uses. However, since VFAs are completely miscible with water and organic solvents and are azeotropic with water, commonly used separation technologies are difficult to achieve effective separation, which has become a key link restricting the resource utilization of kitchen waste.
[0003] Existing separation technologies, such as extraction and membrane separation, can separate VFAs to a certain extent, but they have the following problems: Low separation efficiency: It is difficult to achieve high-purity separation of single acids. Limited application scope: It is mostly used for the separation of mixed acids, and cannot effectively separate single acids such as acetic acid, propionic acid, and butyric acid. Complex process: It requires multiple combined processes, which increases the difficulty and cost of operation.
[0004] Therefore, developing a new method for efficiently separating and extracting high-purity acetic acid, propionic acid, and butyric acid is of great significance for realizing the resource utilization of anaerobic fermentation broth. Summary of the invention
[0005] The present application aims to solve at least one of the technical problems existing in the prior art to a certain extent. To this end, the present application provides a method for separating and extracting acetic acid, propionic acid and butyric acid from anaerobic fermentation broth. The method of the present application can realize efficient and high-purity separation and extraction of acetic acid, propionic acid and butyric acid from anaerobic fermentation broth of kitchen waste. Moreover, while achieving high-value utilization of fermentation broth, waste discharge is reduced, which has significant economic and environmental benefits.
[0006] In one aspect of the present application, the present invention proposes a method for separating and extracting acetic acid, propionic acid and butyric acid from anaerobic fermentation liquid. According to an embodiment of the present application, the method comprises: subjecting the anaerobic fermentation liquid to solid-liquid separation treatment and collecting a first supernatant; subjecting the supernatant to extraction treatment using an organic solvent and collecting an organic phase solution; subjecting the organic phase solution to esterification treatment to obtain an esterification treatment product; subjecting the esterification treatment product to rectification treatment to separate and obtain ethyl acetate, ethyl propionate and ethyl butyrate; subjecting the ethyl acetate to a first decomposition and extraction treatment to obtain acetic acid and ethanol; subjecting the ethyl propionate to a second decomposition and extraction treatment to obtain propionic acid and ethanol; subjecting the ethyl butyrate to a third decomposition and extraction treatment to obtain butyric acid and ethanol.
[0007] Firstly, solid-liquid separation is adopted to effectively remove large suspended solids in the fermentation broth, thereby improving the efficiency of subsequent extraction; since acetic acid, propionic acid and butyric acid are completely miscible with water and organic solvents and can produce azeotropic phenomena, only a mixture of acetic acid, propionic acid and butyric acid can be obtained after distillation; however, the method of the present application does not produce azeotropic phenomena after esterifying acetic acid, propionic acid and butyric acid, and an organic phase solution containing organic acids is reacted with ethanol to obtain an ethyl ester mixture, thereby obtaining ethyl acetate, ethyl propionate and ethyl butyrate respectively after distillation; finally, decomposition and extraction treatment are carried out based on the obtained ethyl acetate, ethyl propionate and ethyl butyrate, and vacuum distillation can obtain high-purity acetic acid, propionic acid and butyric acid respectively; meanwhile, distillation can recover ethanol, and the ethanol is returned to the esterification stage for repeated utilization, thereby improving resource utilization, realizing high-value utilization of fermentation broth, reducing waste discharge, having significant economic and environmental benefits, and meeting the requirements of sustainable development.
[0008] According to an embodiment of the present application, the distillation treatment includes: raising the temperature of the esterification treatment product to 70-80°C to obtain a distillate containing ethyl acetate and a first distillation residual liquid; raising the temperature of the first distillation residual liquid to 100-110°C to obtain a distillate containing ethyl propionate and a second distillation residual liquid; raising the temperature of the second distillation residual liquid to 120-130°C to obtain a distillate containing ethyl butyrate.
[0009] According to an embodiment of the present application, before the extraction treatment, the first supernatant is treated as follows: the first supernatant is flocculated and a second supernatant is collected; the second supernatant is distilled and the distillation residue is collected, and then the distillation residue is subjected to the extraction treatment.
[0010] According to an embodiment of the present application, the extraction process includes: mixing the distillation residue liquid with an extractant; the volume ratio of the distillation residue liquid to the extractant is (2-4):1.
[0011] According to an embodiment of the present application, the temperature of the distillation treatment is 250-300° C.; when the volume of the effluent is 70-90% of the volume of the second supernatant, the distillation treatment is stopped.
[0012] According to an embodiment of the present application, the flocculation treatment includes: mixing polyaluminium chloride with the first supernatant to obtain a mixed solution, mixing polyacrylamide with the mixed solution, and precipitating to obtain the second supernatant.
[0013] According to the embodiments of the present application, it is characterized in that the dosage of the polyaluminium chloride is 800-1500 mg / L; the dosage of the polyacrylamide is 0.5-1 mg / L; and the precipitation time is 20-40 min.
[0014] According to an embodiment of the present application, the anaerobic fermentation liquid includes at least one of kitchen waste, livestock manure, and sludge obtained by anaerobic fermentation.
[0015] According to an embodiment of the present application, the rotation speed of the solid-liquid separation treatment is 5000 to 9000 rpm; the time of the solid-liquid separation treatment is 10 to 20 minutes.
[0016] According to an embodiment of the present application, the extractant includes ethyl acetate.
[0017] According to an embodiment of the present application, the esterification treatment includes: mixing the organic phase solution, ethanol and concentrated sulfuric acid; the volume ratio of the organic phase solution, ethanol and concentrated sulfuric acid is 1:1.5:(0.04~0.05); the temperature of the mixing treatment is 60~70℃.
[0018] According to an embodiment of the present application, the first decomposition treatment includes: the first decomposition and extraction treatment includes: mixing the ethyl acetate with sodium hydroxide to generate a mixture containing sodium acetate and ethanol; subjecting the mixture containing sodium acetate and ethanol to a first distillation to separate ethanol and a first residual liquid, and the temperature of the first distillation is 75 to 85°C; mixing the first residual liquid with concentrated sulfuric acid, and then subjecting the obtained mixed liquid to a second distillation to separate acetic acid, and the temperature of the second distillation is 50 to 60°C, and the vacuum pressure is -0.05 to -0.1MPa.
[0019] According to an embodiment of the present application, the second decomposition and extraction treatment includes: mixing the ethyl propionate with sodium hydroxide to generate a mixture containing sodium propionate and ethanol; subjecting the mixture containing sodium propionate and ethanol to a third distillation to separate ethanol and a second residual liquid, the temperature of the third distillation being 75 to 85°C; mixing the second residual liquid with concentrated sulfuric acid, and then subjecting the obtained mixed liquid to a fourth distillation to separate propionic acid, the temperature of the fourth distillation being 60 to 70°C, and the vacuum pressure being -0.05 to -0.1MPa.
[0020] According to an embodiment of the present application, the third decomposition treatment includes: mixing the ethyl butyrate with sodium hydroxide to generate a mixture containing sodium butyrate and ethanol; subjecting the mixture containing sodium butyrate and ethanol to a fifth distillation to separate ethanol and a third residual liquid, the temperature of the fifth distillation being 75 to 85°C; mixing the third residual liquid with concentrated sulfuric acid, and then subjecting the resulting mixed liquid to a sixth distillation to separate butyric acid, the temperature of the sixth distillation being 70 to 80°C, and the vacuum pressure being -0.05 to -0.1 MPa.
[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:
[0023] Figure 1 This is the process flow chart of anaerobic fermentation liquid recycling for this application. DETAILED DESCRIPTION
[0024] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.
[0025] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.
[0026] The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.
[0027] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.
[0028] As used herein, the terms "optionally", "optional" or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.
[0029] Method for separating and extracting acetic acid, propionic acid and butyric acid from anaerobic fermentation broth
[0030] In one aspect of the present application, the present invention proposes a method for separating and extracting acetic acid, propionic acid and butyric acid from anaerobic fermentation liquid. According to an embodiment of the present application, the method comprises: subjecting the anaerobic fermentation liquid to solid-liquid separation treatment and collecting a first supernatant; subjecting the supernatant to extraction treatment using an organic solvent and collecting an organic phase solution; subjecting the organic phase solution to esterification treatment to obtain an esterification treatment product; subjecting the esterification treatment product to distillation treatment to separate and obtain ethyl acetate, ethyl propionate and ethyl butyrate; subjecting the ethyl acetate to a first decomposition and extraction treatment to obtain acetic acid and ethanol; subjecting the ethyl propionate to a second decomposition and extraction treatment to obtain propionic acid and ethanol; subjecting the ethyl butyrate to a third decomposition and extraction treatment to obtain butyric acid and ethanol.
[0031] Firstly, solid-liquid separation is adopted to effectively remove large suspended solids in the fermentation broth, thereby improving the efficiency of subsequent extraction; since acetic acid, propionic acid and butyric acid are completely miscible with water and organic solvents and can produce azeotropic phenomena, only a mixture of acetic acid, propionic acid and butyric acid can be obtained after distillation; however, the method of the present application does not produce azeotropic phenomena after esterifying acetic acid, propionic acid and butyric acid, and an organic phase solution containing organic acids is reacted with ethanol to obtain an ethyl ester mixture, thereby obtaining ethyl acetate, ethyl propionate and ethyl butyrate respectively after distillation; finally, decomposition and extraction treatment are carried out based on the obtained ethyl acetate, ethyl propionate and ethyl butyrate, and vacuum distillation can obtain high-purity acetic acid, propionic acid and butyric acid respectively; meanwhile, distillation can recover ethanol, and the ethanol is returned to the esterification stage for repeated utilization, thereby improving resource utilization, realizing high-value utilization of fermentation broth, reducing waste emissions, having significant economic and environmental benefits, and meeting the requirements of sustainable development.
[0032] According to an embodiment of the present application, the distillation treatment includes: raising the temperature of the esterification treatment product to 70-80°C to obtain a distillate containing ethyl acetate and a first distillation residual liquid; raising the temperature of the first distillation residual liquid to 100-110°C to obtain a distillate containing ethyl propionate and a second distillation residual liquid; raising the temperature of the second distillation residual liquid to 120-130°C to obtain a distillate containing ethyl butyrate. Thus, by precisely controlling the temperature and utilizing the difference in boiling points of different esterification products, ethyl acetate, ethyl propionate and ethyl butyrate can be separated from the mixed esterification product with high efficiency and high purity, providing pure raw materials for the subsequent hydrolysis and purification steps, which is a key step to achieve high purity and high recovery rate of the final products acetic acid, propionic acid and butyric acid.
[0033] According to an embodiment of the present application, before the extraction treatment, the first supernatant is treated as follows: the first supernatant is flocculated and the second supernatant is collected; the second supernatant is distilled and the residual distillation liquid is collected, and the residual distillation liquid is subjected to the extraction treatment. Thus, by adding a flocculant to remove soluble proteins and other suspended particles, the interference of these impurities on the extraction process is reduced, and the selectivity and extraction efficiency of the extractant are improved; by distillation treatment, part of the water is removed, the organic acid is concentrated, and the concentration of the organic acid in the solution is further increased, providing a more enriched target substance for the extraction step, so that the extraction process can be carried out more efficiently, and finally the extraction of high-purity organic acids is achieved.
[0034] According to an embodiment of the present application, the extraction treatment includes: mixing the distillation residue with an extractant; the volume ratio of the distillation residue to the extractant is (2-4):1, for example, 2:1, 3:1, 4:1. Thus, the organic acid is efficiently transferred from the aqueous phase to the organic phase by utilizing the selective affinity of the extractant for the organic acid, thereby achieving separation of the organic acid from the aqueous phase.
[0035] According to an embodiment of the present application, the temperature of the distillation treatment is 250-300°C; when the volume of the effluent is 70-90% of the volume of the second supernatant, the distillation treatment is stopped. Thus, most of the water in the second supernatant is effectively removed by distillation, thereby concentrating the organic acid components therein.
[0036] According to an embodiment of the present application, the flocculation treatment includes: mixing polyaluminium chloride with the first supernatant to obtain a mixed solution, mixing polyacrylamide with the mixed solution, and precipitating to obtain the second supernatant. Thus, PAC can form larger flocs with impurities in the water, while PAM further enhances the flocculation effect, promotes the sedimentation of flocs, reduces the interference of impurities on subsequent extraction and distillation steps, and improves the efficiency of the entire process and the purity of the final product.
[0037] According to the embodiment of the present application, it is characterized in that the dosage of the polyaluminium chloride is 800-1500 mg / L; the dosage of the polyacrylamide is 0.5-1 mg / L; and the precipitation time is 20-40 min. Thus, the interference of impurities on the subsequent extraction and distillation steps is further reduced, and the efficiency of the entire process and the purity of the final product are improved.
[0038] It should be noted that the term "anaerobic fermentation liquid" refers to the fermentation liquid obtained by anaerobic fermentation. The conditions of anaerobic fermentation are not strictly limited, as long as the obtained fermentation liquid contains acetic acid, propionic acid and butyric acid. In some embodiments, the anaerobic fermentation liquid includes at least one of kitchen waste, livestock manure, and sludge obtained by anaerobic fermentation. Therefore, the method of the present application has wide applicability and flexibility.
[0039] According to the embodiment of the present application, the rotation speed of the solid-liquid separation treatment is 5000-9000 rpm, and the solid-liquid separation treatment time is 10-20 minutes. Thus, the solid particles and suspended matter in the fermentation liquid are further precipitated, and the separated supernatant not only reduces the impurity content, but also improves the efficiency and effect of the subsequent treatment steps.
[0040] According to an embodiment of the present application, the extractant includes ethyl acetate. Thus, ethyl acetate can efficiently transfer the organic acid from the aqueous phase to the organic phase.
[0041] According to an embodiment of the present application, the esterification treatment includes: mixing the organic phase solution, ethanol and concentrated sulfuric acid; the volume ratio of the organic phase solution, ethanol and concentrated sulfuric acid is 1:1.5:(0.04-0.05), for example, it can be 1:1.5:0.04, 1:1.5:0.045, 1:1.5:0.05; the temperature of the mixing treatment is 60-70°C. Thus, the organic acid is converted into the corresponding ester compounds, namely ethyl acetate, ethyl propionate and ethyl butyrate, and the efficient esterification reaction is ensured by accurately controlling the ratio and temperature of the reactants, thereby improving the yield and purity of the esterification product.
[0042] According to an embodiment of the present application, the first decomposition treatment includes: the first decomposition and extraction treatment includes: mixing the ethyl acetate with sodium hydroxide to generate a mixture containing sodium acetate and ethanol; subjecting the mixture containing sodium acetate and ethanol to a first distillation to separate ethanol and a first residual liquid, the temperature of the first distillation being 75 to 85°C; mixing the first residual liquid with concentrated sulfuric acid, and then subjecting the obtained mixed liquid to a second distillation to separate acetic acid, the temperature of the second distillation being 50 to 60°C, and the vacuum pressure being -0.05 to -0.1MPa. Thus, the method of the present application can separate high-purity acetic acid from anaerobic fermentation liquid.
[0043] According to an embodiment of the present application, the second decomposition and extraction process includes: mixing the ethyl propionate with sodium hydroxide to generate a mixture containing sodium propionate and ethanol; subjecting the mixture containing sodium propionate and ethanol to a third distillation to separate ethanol and a second residual liquid, wherein the temperature of the third distillation is 75 to 85°C; mixing the second residual liquid with concentrated sulfuric acid, and then subjecting the obtained mixed liquid to a fourth distillation to separate propionic acid, wherein the temperature of the fourth distillation is 60 to 70°C, and the vacuum pressure is -0.05 to -0.1 MPa. Thus, the method of the present application can separate high-purity propionic acid from anaerobic fermentation liquid.
[0044] According to an embodiment of the present application, the third decomposition treatment includes: mixing the ethyl butyrate with sodium hydroxide to generate a mixture containing sodium butyrate and ethanol; subjecting the mixture containing sodium butyrate and ethanol to a fifth distillation to separate ethanol and a third residual liquid, wherein the temperature of the fifth distillation is 75 to 85°C; mixing the third residual liquid with concentrated sulfuric acid, and subjecting the obtained mixed liquid to a sixth distillation to separate butyric acid, wherein the temperature of the sixth distillation is 70 to 80°C, and the vacuum pressure is -0.05 to -0.1 MPa. Thus, the method of the present application can separate high-purity butyric acid from anaerobic fermentation liquid.
[0045] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.
[0046] Embodiment 1:
[0047] In this embodiment, see Figure 1 , the volatile fatty acids in the anaerobic fermentation broth are recovered and utilized according to the following method:
[0048] A. Solid-liquid separation: The anaerobic fermentation liquid of kitchen waste containing volatile fatty acids was centrifuged at 9000 rpm for 15 min to obtain supernatant I.
[0049] B. Removal of soluble proteins in the fermentation broth: flocculate the supernatant I. The flocculants are polyaluminium chloride (PAC) and polyacrylamide (PAM). First, add PAC at a dosage of 1500 mg / L. After stirring for 1 min, add PAM at a dosage of 1 mg / L. Let it settle for 30 min to obtain supernatant II.
[0050] C. Distill and concentrate the supernatant: distill the supernatant II at atmospheric pressure and control the distillation temperature to 275°C; stop distilling when the effluent is 90% of the supernatant.
[0051] D. Organic acid extraction: Use hydrophobic ethyl acetate as the extractant, and stir for about 10 minutes to fully mix the residual liquid and ethyl acetate in a volume ratio of 2:1. Pour into a separatory funnel for separation, the lower layer is the water phase, and the upper layer is the organic phase; extract the water phase repeatedly for 3 times, and mix the organic phases obtained from each treatment to form an organic phase mixed solution. The organic acid extraction rate of ethyl acetate treatment is 94.2%.
[0052] E. Esterification with organic acids: the volume ratio of the extract to ethanol to concentrated sulfuric acid is 1:1.5:0.045, and the esterification reaction is carried out at 65°C to obtain a mixed solution containing ethyl acetate, ethyl propionate and ethyl butyrate;
[0053] F. Distillation: The mixed solution is subjected to multi-stage atmospheric distillation. The specific steps are as follows:
[0054] a. Control the temperature to 75°C and distill to obtain ethyl acetate;
[0055] b. Control the temperature to 105°C and distill to obtain ethyl propionate;
[0056] c. Control the temperature to 125°C and distill to obtain ethyl butyrate;
[0057] G. Decomposition: Add sodium hydroxide to ethyl acetate and heat to maintain at 70°C to generate sodium acetate and ethanol respectively; add sodium hydroxide to ethyl propionate and heat to maintain at 70°C to generate sodium propionate and ethanol; add sodium hydroxide to ethyl butyrate and heat to maintain at 70°C to generate sodium butyrate and ethanol;
[0058] H. Distillation: Control the temperature at 80°C, and the effluent is ethanol. Then add concentrated sulfuric acid to the remaining liquid for distillation. The specific steps are as follows:
[0059] A. Control the vacuum pressure to -0.09 MPa and the temperature to 55°C, and obtain acetic acid by vacuum distillation. The acetic acid recovery rate is 80%;
[0060] B. Control the vacuum pressure to -0.09MPa and the temperature to 65℃, and obtain propionic acid by vacuum distillation. The recovery rate of propionic acid is 85%
[0061] C. Control the vacuum pressure to -0.09 MPa and the temperature to 75°C, and obtain butyric acid by reduced pressure distillation. The butyric acid recovery rate is 85%.
[0062] Embodiment 2:
[0063] In this embodiment, see Figure 1, the volatile fatty acids in the anaerobic fermentation broth are recovered and utilized according to the following method:
[0064] A. Solid-liquid separation: The anaerobic fermentation liquid of kitchen waste containing volatile fatty acids was centrifuged at 5000 rpm for 15 min to obtain supernatant I.
[0065] B. Removal of soluble proteins in the fermentation broth: flocculate the supernatant I. The flocculants are polyaluminium chloride (PAC) and polyacrylamide (PAM). First, add PAC at a dosage of 800 mg / L. After stirring for 1 min, add PAM at a dosage of 0.5 mg / L. Let it settle for 30 min to obtain supernatant II.
[0066] C. Distill and concentrate the supernatant: distill the supernatant II at atmospheric pressure and control the distillation temperature to 275°C; stop distilling when the effluent is 70% of the supernatant.
[0067] D. Organic acid extraction: Use hydrophobic ethyl acetate as the extractant, and stir for about 10 minutes to fully mix the residual liquid and ethyl acetate in a volume ratio of 4:1. Pour into a separatory funnel for separation, the lower layer is the water phase, and the upper layer is the organic phase; extract the water phase repeatedly for 3 times, and mix the organic phases obtained from each treatment to form an organic phase mixed solution. The organic acid extraction rate of ethyl acetate treatment is 90.1%.
[0068] E. Esterification with organic acids: the volume ratio of the extract to ethanol to concentrated sulfuric acid is 1:1.5:0.045, and the esterification reaction is carried out at 65°C to obtain a mixed solution containing ethyl acetate, ethyl propionate and ethyl butyrate;
[0069] F. Distillation: The mixed solution is subjected to multi-stage atmospheric distillation. The specific steps are as follows:
[0070] a. Control the temperature to 75°C and distill to obtain ethyl acetate;
[0071] b. Control the temperature to 105°C and distill to obtain ethyl propionate;
[0072] c. Control the temperature to 125°C and distill to obtain ethyl butyrate;
[0073] G. Decomposition: Add sodium hydroxide to ethyl acetate and heat to maintain at 70°C to generate sodium acetate and ethanol respectively; add sodium hydroxide to ethyl propionate and heat to maintain at 70°C to generate sodium propionate and ethanol; add sodium hydroxide to ethyl butyrate and heat to maintain at 70°C to generate sodium butyrate and ethanol;
[0074] H. Distillation: Control the temperature at 80°C, and the effluent is ethanol. Then add concentrated sulfuric acid to the remaining liquid for distillation. The specific steps are as follows:
[0075] A. Control the vacuum pressure to -0.09 MPa and the temperature to 55°C, and obtain acetic acid by vacuum distillation. The acetic acid recovery rate is 70%;
[0076] B. Control the vacuum pressure to -0.09MPa and the temperature to 65℃, and obtain propionic acid by vacuum distillation. The recovery rate of propionic acid is 70%
[0077] C. Control the vacuum pressure to -0.09 MPa and the temperature to 75°C, and obtain butyric acid by reduced pressure distillation. The butyric acid recovery rate is 75%.
[0078] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.
[0079] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.
Claims
1. A method for separating and extracting acetic acid, propionic acid and butyric acid from anaerobic fermentation broth, characterized in that: include: The anaerobic fermentation liquid is subjected to solid-liquid separation treatment to collect a first supernatant; Extracting the supernatant with an organic solvent and collecting an organic phase solution; The organic phase solution is subjected to esterification treatment to obtain an esterification product; The esterification product is subjected to rectification treatment to separate ethyl acetate, ethyl propionate and ethyl butyrate; The ethyl acetate is subjected to a first decomposition and extraction treatment to obtain acetic acid and ethanol; The ethyl propionate is subjected to a second decomposition and extraction treatment to obtain propionic acid and ethanol; The ethyl butyrate is subjected to a third decomposition and extraction treatment to obtain butyric acid and ethanol.
2. The method according to claim 1, characterized in that The distillation treatment comprises: The temperature of the esterification product is raised to 70-80° C. to obtain a distillate containing ethyl acetate and a first distillation residual liquid; Raising the temperature of the first distillation residual liquid to 100-110° C. to obtain a distillate containing ethyl propionate and a second distillation residual liquid; The temperature of the second distillation residue is raised to 120-130° C. to obtain a distillate containing ethyl butyrate.
3. The method according to claim 1, characterized in that Before the extraction process, the first supernatant is treated as follows: flocculating the first supernatant and collecting the second supernatant; The second supernatant is subjected to distillation treatment, the distillation residue is collected, and the distillation residue is subjected to the extraction treatment.
4. The method according to claim 3, characterized in that The extraction process comprises: mixing the distillation residue with an extractant; The volume ratio of the distillation residue to the extractant is (2-4):
1.
5. The method according to claim 3, characterized in that: The temperature of the distillation treatment is 250-300° C.; when the volume of the effluent is 70-90% of the volume of the second supernatant, the distillation treatment is stopped; Optionally, the flocculation treatment includes: mixing polyaluminium chloride with the first supernatant to obtain a mixed solution, mixing polyacrylamide with the mixed solution, and precipitating to obtain the second supernatant.
6. The method according to claim 5, characterized in that The dosage of the polyaluminium chloride is 800-1500mg / L; The dosage of the polyacrylamide is 0.5-1 mg / L; The precipitation time is 20 to 40 minutes.
7. The method according to claim 1, characterized in that The anaerobic fermentation liquid comprises at least one of kitchen waste, livestock excrement and sludge obtained by anaerobic fermentation; Optionally, the rotation speed of the solid-liquid separation treatment is 5000-9000 rpm; the time of the solid-liquid separation treatment is 10-20 min; Optionally, the extractant comprises ethyl acetate.
8. The method according to claim 1, characterized in that The esterification treatment comprises: mixing the organic phase solution, ethanol and concentrated sulfuric acid; The volume ratio of the organic phase solution, ethanol and concentrated sulfuric acid is 1:1.5:(0.04-0.05); The temperature of the mixing treatment is 60-70°C.
9. The method according to claim 1, characterized in that: The first decomposition and extraction process comprises: The ethyl acetate is mixed with sodium hydroxide to generate a mixture containing sodium acetate and ethanol; The mixture containing sodium acetate and ethanol is subjected to a first distillation to separate ethanol and a first residual liquid, wherein the temperature of the first distillation is 75-85° C.; The first residual liquid is mixed with concentrated sulfuric acid, and the obtained mixed liquid is subjected to a second distillation to separate acetic acid, wherein the temperature of the second distillation is 50 to 60° C. and the vacuum pressure is -0.05 to -0.1 MPa; Optionally, the second decomposition and extraction process comprises: The ethyl propionate is mixed with sodium hydroxide to generate a mixture containing sodium propionate and ethanol; The mixture containing sodium propionate and ethanol is subjected to a third distillation to separate ethanol and a second residual liquid, wherein the temperature of the third distillation is 75-85° C.; The second residual liquid is mixed with concentrated sulfuric acid, and the obtained mixed liquid is subjected to a fourth distillation to separate propionic acid, wherein the temperature of the fourth distillation is 60 to 70° C. and the vacuum pressure is -0.05 to -0.1 MPa; Optionally, the third decomposition and extraction process comprises: The ethyl butyrate is mixed with sodium hydroxide to generate a mixture containing sodium butyrate and ethanol; The mixture containing sodium butyrate and ethanol is subjected to a fifth distillation to separate ethanol and a third residual liquid, wherein the temperature of the fifth distillation is 75-85° C.; The third residual liquid is mixed with concentrated sulfuric acid, and the obtained mixed liquid is subjected to a sixth distillation to separate butyric acid. The temperature of the sixth distillation is 70 to 80° C., and the vacuum pressure is -0.05 to -0.1 MPa.