Method for co-producing lactic acid and hydroxyacetone from enteromorpha and rhamnose derived from enteromorpha

Abstract

The invention discloses a method for co-producing lactic acid and hydroxyacetone from enteromorpha and derivative rhamnose thereof, which comprises the following steps: adding 100 parts by mass of substrate, 50-200 parts by mass of catalyst CeO2-R and a proper amount of deionized water into a reaction kettle, and reacting for 60 minutes under the conditions that the pressure of the reaction kettle is 2 MPa and the temperature is 180 DEG C in an initial N2 atmosphere; and then cooling and reducing pressure, filtering out the solid catalyst, and carrying out HPLC (High Performance Liquid Chromatography) detection and filtration on the reaction liquid to obtain small molecules, namely the product. The catalytic system is also suitable for catalytic conversion of C3 intermediates and co-production of lactic acid and hydroxyacetone under the hydrogen-free condition, a reaction system for co-production of lactic acid and hydroxyacetone from enteromorpha and rhamnose derived from enteromorpha under the hydrogen-free condition is established for the first time, the application of enteromorpha is expanded, and proliferation of solid waste resources such as enteromorpha is achieved. The catalyst is simple in preparation process and good in stability, the total yield of lactic acid and hydroxyacetone can reach 60% or above, and the catalyst has good application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of biochemistry, in particular to a method for co-producing lactic acid and hydroxyacetone from Enteromorpha and rhamnose derived therefrom. Background Art

[0002] Lactic acid (2-hydroxypropionic acid) is one of the 30 major platform compounds identified by the U.S. Department of Energy. It is widely used in food, medicine, cosmetics, polylactic acid and other industries. In food and related fields, lactic acid can be used as flavoring agent, acidulant, preservative, etc. In medicine, lactic acid can be used as preservative, drug carrier, etc. In the cosmetics industry, lactic acid can be used as skin moisturizer, pH regulator of shampoo, etc. Polylactic acid prepared with lactic acid as raw material can be used to prepare fully biodegradable plastics, replacing polyethylene, polyvinyl chloride and other materials, which can effectively reduce the pollution of white garbage. Hydroxyacetone (1-hydroxy-2-propanone) is a non-toxic and harmless product. Due to its two functional groups, hydroxyl and carbonyl, it has high reactivity and can undergo oxidation, polymerization, dehydration and other reactions. It is an important chemical intermediate and organic synthesis raw material. It is widely used in catalytic steam hydrogen production, fixing dyes in the textile industry, skin tanning agents, green solvents, flavoring agents, and intermediates for fine chemicals and pharmaceuticals. For example, in the food industry, hydroxyacetone can bring a fragrance to food that is almost the same as proline, valine and isoleucine, and is often used as a bread flavoring ingredient; in the textile industry, hydroxyacetone can replace sodium bisulfite to reduce dyes to form water-soluble compounds; in addition, in the cosmetics industry, hydroxyacetone can be used as the main ingredient of skin tanning agents.

[0003] Traditional methods for producing lactic acid mainly include chemical synthesis and microbial fermentation: (i) lactic acid hydrolysis; (ii) acrylonitrile hydrolysis; (iii) propionic acid method; (iv) carbohydrate fermentation. Traditional methods for producing hydroxyacetone mainly include: (i) bromoacetone reacts with sodium formate to form esters, followed by hydrolysis; (ii) direct oxidation of acetone using Bayer-Villiger peroxide reagent; (iii) palladium-catalyzed dehydration and oxidation of 1,2-propylene glycol in the presence of hydrogen peroxide; (iv) biosynthetic pathway using microbial fermentation. Although the production of lactic acid by biological fermentation is relatively mature, its production efficiency and cost-effectiveness still need to be improved. The fermentation process usually requires strict aseptic conditions and precise control, which increases production costs and operational complexity. In addition, the fermentation method's dependence on raw materials limits its potential for large-scale production. Chemical catalysis provides an alternative route that can theoretically directly convert sugar compounds into lactic acid, but the method currently still faces problems such as low catalyst selectivity, many side reactions and high costs. At present, the chemical catalytic method for preparing hydroxyacetone mainly focuses on the dehydration reaction of glycerol in fixed bed or continuous reactors. There are relatively few studies on the preparation of hydroxyacetone from renewable sugar compounds, and all of them need to be achieved under the condition of external hydrogen source. However, the co-production of lactic acid and hydroxyacetone from renewable biomass resources under hydrogen-free conditions has not been reported so far.

[0004] Enteromorpha is a kind of algae waste rich in sugar, mainly containing rhamnose (~18.1 wt%), glucose (~13.5 wt%), xylose (~8.2 wt%), etc. In recent years, it has been erupting in the Yellow Sea of ​​my country, which not only causes environmental pollution but also wastes resources. How to transform Enteromorpha into high-value chemicals and turn Enteromorpha into "treasure" is of great research significance to the sustainable development of human society. Summary of the invention

[0005] The object of the present invention is to overcome the above-mentioned background technical difficulties and provide a method for co-producing lactic acid and hydroxyacetone from Enteromorpha and its derivative rhamnose under hydrogen-free conditions.

[0006] To achieve the above purpose, the technical scheme adopted is: a method for co-producing lactic acid and hydroxyacetone from Enteromorpha and its derivative rhamnose, wherein 100 parts of substrate, 50-200 parts of catalyst and an appropriate amount of deionized water are added into a reactor in parts by mass, the pressure of the reactor is 2 MPa, the temperature is 100-200°C under an initial N2 atmosphere, and the reaction time is 1-180 min; then, after cooling and decompression, the solid catalyst is filtered out, and the small molecules obtained after the reaction liquid is filtered by HPLC detection are the products lactic acid and hydroxyacetone; the substrate is Enteromorpha or its derivative rhamnose; the catalyst is one or more of CeO2, Fe2O3, TiO2, Al2O3, ZnO, MnO2, MgO, Y2O3, and La2O3.

[0007] Furthermore, the catalyst is CeO2-R having a fishing rod (rod) shape.

[0008] Furthermore, the preparation method of CeO2-R is as follows: adding a certain amount of Ce precursor Ce(NO3)3·6H2O to 100 mL of water to dissolve, ultrasonically stirring for 10 min to dissolve and disperse the Ce component, then quickly adding 24 g of NaOH and transferring to a hydrothermal kettle; setting the rotation speed to 200 rpm, the reaction temperature to 100 °C, and the reaction time to 24 h; after the reaction, filtering, washing, and drying the obtained solid, and calcining it in a tubular furnace in an air atmosphere at 450 °C, 5 °C / min, for 3 h to obtain CeO2-R with a fish rod shape.

[0009] Furthermore, the filtered solid catalyst was placed in an oven and dried at 80°C for 10 h, and then placed in a tubular furnace in an air atmosphere and calcined at 450°C for 3 h, and can be reused.

[0010] Furthermore, the reaction temperature is 180°C.

[0011] Furthermore, the reaction time is 60 min.

[0012] Furthermore, the catalyst is 100 parts.

[0013] Furthermore, the reaction substrate can be replaced by a C3 intermediate.

[0014] The beneficial effects of adopting the above scheme are as follows: the catalytic system in the present invention is also applicable to the catalytic conversion of Enteromorpha, and co-production of lactic acid and hydroxyacetone under hydrogen-free conditions. For the first time, a reaction system for co-production of lactic acid and hydroxyacetone from Enteromorpha and its derivative rhamnose under hydrogen-free conditions has been established, which expands the application of Enteromorpha and realizes the value-added of solid waste resources such as Enteromorpha. The catalyst preparation process is simple, the stability is good, the total yield of lactic acid and hydroxyacetone can reach more than 60%, and it has good application prospects. DETAILED DESCRIPTION

[0015] The technical scheme of the present invention is clearly and completely described below in conjunction with the specific embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0016] It should be understood that the following terms included in the text may be for the convenience of description and simplification of description, or are merely based on the relationship shown in the legend, rather than indicating or implying a specific relationship that is required. Technical personnel in this field need to make a broad understanding in conjunction with the full text, and it cannot be interpreted as a limitation on the present technical solution.

[0017] The present invention analyzes the structure of rhamnose and finds that the design of a suitable catalyst can achieve the co-production of lactic acid and hydroxyacetone. In view of this, the present invention uses cheap rhamnose derived from Enteromorpha as a reaction raw material, designs and prepares different metal oxides and CeO2 with different morphologies as a catalyst, uses water as a solvent, and co-produces lactic acid and hydroxyacetone with high yield and high selectivity under a N2 atmosphere. The solid catalyst can be directly separated from the reaction solution by vacuum filtration, which is convenient for product purification and catalyst reuse.

[0018] The present invention designs and prepares different metal oxide catalysts for catalytic conversion of enteromorpha-derived rhamnose to co-produce lactic acid and hydroxyacetone, among which CeO2 exhibits the best catalytic activity. The solid catalyst is easy to prepare, has low cost, and has high catalytic efficiency, and the yield of lactic acid and hydroxyacetone obtained is high. CeO2 with different morphologies was further prepared, and the study found that the fish rod-shaped (rod-shaped) CeO2 (CeO2-R) had the highest catalytic activity. At the same time, after the reaction, the solid catalyst can be recovered by simple filtration, and the reuse rate is high. This method fills the gap in the chemical catalytic method for catalyzing the co-production of lactic acid and hydroxyacetone by sugar compounds under hydrogen-free conditions, and also overcomes the shortcomings of low production efficiency and long reaction cycle of traditional synthesis methods and microbial methods.

[0019] Embodiment 1-10: 1) A certain amount of Ce precursor (Ce(NO3)3·6H2O) was calcined at 450 ℃ (5℃ / min) for 3 h in a tube furnace in an air atmosphere to obtain nano-CeO2 (CeO2-N).

[0020] 2) Add 100 mg rhamnose, 100 mg CeO2-N catalyst, and 50 mL deionized water to a 100 mL autoclave. After sealing the autoclave, introduce N2 into the autoclave to maintain its pressure at 2 MPa. Stir and heat to 180 °C for 60 min. Remove the autoclave from the heating device and quickly cool it to room temperature. Open the autoclave and separate the solid-liquid mixture in the autoclave by vacuum filtration to obtain a solid residue and a product mixture.

[0021] 3) The collected solid residue was washed with deionized water for 3 times, placed in an oven, dried, and then placed in a tube furnace in an air atmosphere and calcined at 450 °C for 3 h for the next catalytic reaction. The small molecule products in the reaction solution were detected by HPLC, and the results are shown in Table 1 (the yield in the table is the carbon molar yield, product yield = carbon molar amount of the obtained product / carbon molar amount of the added raw material × 100%).

[0022] Table 1 Implementation Cases catalyst Conversion rate Glycolic acid lactic acid Formic acid Hydroxyacetone Lactic acid + hydroxyacetone 1 <![CDATA[CeO2-N]]> 99.8% 2.5% 24.7% 4.1% 36.1 % 60.8% 2 CuO 71.8% 3.4% 1.8% 1.0% 4.3% 6.1% 3 <![CDATA[Fe2O3]]> 70.7% 2.1% 4.0% 6.9% 7.7% 11.7% 4 <![CDATA[TiO2]]> 71.2% 1.1% 5.6% 2.0% 15.3% 20.9% 5 <![CDATA[Al2O3]]> 99.8% 2.0% 16.9% 5.2% 23.1% 40.0% 6 ZnO 99.8% 2.5% 22.7% 15.7% 30.9% 53.6% 7 <![CDATA[MnO2]]> 99.8% 2.8% 26.7% 16.7% 23.1% 49.8% 8 MgO 99.8% 2.6% 23.7% 11.0% 30.6% 54.3% 9 <![CDATA[Y2O3]]> 99.8% 2.5% 18.9% 2.5% 24.6% 43.5% 10 <![CDATA[La2O3]]> 99.8% 3.6% 19.6% 2.3% 27.9% 47.5% From the results in Table 1, it can be seen that there are huge differences in the catalytic activity of different metal oxides in the co-production of lactic acid and hydroxyacetone from rhamnose. Among them, CeO2-N has the best catalytic activity.

[0023] Embodiment 11-13: The experimental steps are the same as those in Example 1, except that the morphology of the selected CeO2 catalyst is different, and other conditions remain unchanged.

[0024] I. A certain amount of Ce precursor (Ce(NO3)3·6H2O) was added to 100 mL of water to dissolve, and ultrasonically stirred for 10 min to facilitate the dissolution and dispersion of the Ce component. Then 24 g of NaOH was quickly added and transferred to a hydrothermal reactor. The speed was set to 200 rpm, the reaction temperature was set to 100 ℃, and the reaction time was set to 24 h. After the reaction, the obtained solid was filtered, washed, and dried, and calcined at 450 ℃ (5 ℃ / min) for 3 h in a tube furnace in an air atmosphere to obtain fish rod-shaped CeO2 (CeO2-R).

[0025] II. A certain amount of Ce precursor (Ce(NO3)3·6H2O) was dissolved in deionized water, dispersed by ultrasonic stirring, and NaOH(aq) was slowly dripped into it to make the final system NaOH(aq) concentration 0.1 M. After stirring for 30 min, it was transferred to a hydrothermal reactor, the speed was set to 200 rpm, and the reaction was carried out at 150 ℃ and 180 ℃ for 24 h. After the reaction, the obtained solid was filtered, washed, and dried, and calcined at 450 ℃ (5 ℃ / min) for 3 h in a tube furnace in an air atmosphere to obtain spherical (150 ℃) CeO2 (CeO2-S) and cubic (180 ℃) CeO2 (CeO2-C).

[0026] The specific results are listed in Table 2 (the yield in the table is the carbon molar yield).

[0027] Table 2 Implementation Cases catalyst Conversion rate Glycolic acid lactic acid Formic acid Hydroxyacetone Lactic acid + hydroxyacetone 11 <![CDATA[CeO2-S]]> 99.8% 3.2% 22.8% 3.0% 39.5% 62.3% 12 <![CDATA[CeO2-R]]> 99.8% 3.0% 24.5% 4.1% 39.8% 64.3% 13 <![CDATA[CeO2-C]]> 99.8% 3.2% 20.0% 7.6% 35.0% 55.0% Combining the results of Example 1 and Table 2, it can be seen that CeO2 with different morphologies, especially CeO2-C, has significant differences in the catalytic activity of rhamnose co-production of lactic acid and hydroxyacetone under hydrogen-free conditions. Among them, the fish rod-shaped CeO2 (CeO2-R) has the highest catalytic activity.

[0028] Embodiment 14-17: The experimental steps are the same as those in Example 12, except that the reaction temperature is different and other conditions remain unchanged. The specific results are listed in Table 3 (the yield in the table is the carbon molar yield).

[0029] Table 3 Implementation Cases Reaction temperature Conversion rate Glycolic acid lactic acid Formic acid Hydroxyacetone Lactic acid + hydroxyacetone 14 160 ℃ 92.5% 1.1% 15.4% 2.0% 27.8% 43.2% 15 170 ℃ 98.6% 1.9% 19.2% 3.5% 34.3% 53.5% 16 190 ℃ 99.8% 2.3% 24.6% 4.6% 38.7% 63.3% 17 200 ℃ 99.8% 2.0% 24.9% 5.0% 38.2% 63.1% Combining the results of Example 12 and Table 3, it can be seen that as the reaction temperature increases, the yields of lactic acid and hydroxyacetone continue to increase. When the reaction temperature reaches 100 °C, the yields of lactic acid and hydroxyacetone increase significantly; when the reaction temperature is >180 °C, the yields of lactic acid and hydroxyacetone do not change significantly when the reaction temperature continues to increase.

[0030] Embodiment 18-22: The experimental steps are the same as those in Example 12, except that the reaction time is different and other conditions remain unchanged. The specific results are listed in Table 4 (the yield in the table is the carbon molar yield).

[0031] Table 4 Implementation Cases Reaction temperature Conversion rate Glycolic acid lactic acid Formic acid Hydroxyacetone Lactic acid + hydroxyacetone 18 1 min 60.2% 0.4% 4.9% 0.8% 10.3% 15.2% 19 30 min 99.8% 1.9% 18.8% 2.6% 27.7% 46.5% 20 90 min 99.8% 3.5% 22.9% 4.4% 38.5% 61.4% 21 120 min 99.8% 4.1% 19.8% 5.2% 36.7% 56.5% 22 150 min 99.8% 5.0% 19.0% 5.8% 35.2% 54.2% Combining the results of Example 12 and Table 4, it can be seen that as the reaction time increases, the yields of lactic acid and hydroxyacetone continue to increase. After exceeding 60 min, the reaction time continues to increase, the yields of lactic acid and hydroxyacetone decrease, and the yields of formic acid and glycolic acid increase. After the reaction time exceeds 180 min, the yields of lactic acid and hydroxyacetone decrease significantly.

[0032] Embodiment 23-26: The experimental steps are the same as those in Example 12, except that the amount of catalyst used is different. Other conditions remain unchanged. The specific results are listed in Table 5 (the yield in the table is the carbon molar yield).

[0033] Table 5 Implementation Cases Catalyst dosage Conversion rate Glycolic acid lactic acid Formic acid Hydroxyacetone Lactic acid + hydroxyacetone 23 50 mg 99.8% 1.4% 15.2% 2.0% 27.4% 42.6% 24 75 mg 99.8% 2.1% 19.4% 2.9% 33.6% 53.0% 25 125 mg 99.8% 3.5% 25.1% 4.8% 40.1% 65.2% 26 150 mg 99.8% 4.0% 25.4% 5.5% 41.2% 66.6% Combining the results of Example 12 and Table 5, it can be seen that the yields of lactic acid and hydroxyacetone increase continuously with increasing catalyst dosage, and when the catalyst dosage exceeds 100 mg, the yield growth is not obvious. When the catalyst dosage exceeds 200 mg, the yield no longer increases.

[0034] Embodiment 27-30: The experimental steps are the same as those in Example 12, except that the catalyst is reused for different times and other conditions remain unchanged. The specific results are listed in Table 7 (the yield in the table is the carbon molar yield).

[0035] Table 7 Implementation Cases Cycle times Conversion rate Glycolic acid lactic acid Formic acid Hydroxyacetone Lactic acid + hydroxyacetone 27 1 99.5% 2.9% 24.2% 3.8% 39.3% 63.5% 28 2 99.0% 2.6% 23.1% 3.4% 38.6% 61.7% 29 3 98.8% 2.5% 23.0% 3.2% 38.0% 61.0% 30 4 98.8% 2.5% 23.1% 3.1% 37.8% 60.9% Combining the results of Example 12 and Table 7, it can be seen that the prepared CeO2-R catalyst exhibits good stability in the process of catalytic conversion of rhamnose to co-produce lactic acid and hydroxyacetone under hydrogen-free conditions.

[0036] Examples 31-33: The experimental steps were the same as those in Example 12, except that different reaction substrates were used, and when lactaldehyde was used as the substrate, the reaction temperature was 150° C. Enteromorpha was hydrolyzed with oxalic acid and purified for use in the reaction, and other conditions remained unchanged. The specific results are listed in Table 8 (the yield in the table is the carbon molar yield).

[0037] Table 8 Implementation Cases Reaction substrate Conversion rate lactic acid Hydroxyacetone 31 1,3-Dihydroxyacetone 99.8% 95.5% <0.2% 32 Lactaldehyde 99.8% <0.2% 96.6% 33 Enteromorpha - 25.3% 16.1% Combining the results of Example 12 and Table 8, it can be seen that the above catalytic system can be used to catalyze C3 intermediates to generate lactic acid or hydroxyacetone, 1,3-dihydroxyacetone to generate lactic acid, and lactaldehyde to generate hydroxyacetone. Further application to Enteromorpha can also produce lactic acid and hydroxyacetone.

[0038] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0039] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for co-producing lactic acid and hydroxyacetone from Enteromorpha and its derivative rhamnose, characterized in that: According to the mass ratio, 100 parts of substrate, 50-200 parts of catalyst and appropriate amount of deionized water are added into a reactor, the pressure of the reactor is 2 MPa, the temperature is 100-200 °C under the initial N2 atmosphere, and the reaction time is 1-180 min; then after cooling and decompression, the solid catalyst is filtered out, and the small molecules obtained after the reaction liquid is filtered by HPLC detection are the products lactic acid and hydroxyacetone; the substrate is Enteromorpha or its derivative rhamnose; the catalyst is one or more of CeO2, Fe2O3, TiO2, Al2O3, ZnO, MnO2, MgO, Y2O3, and La2O3.

2. The method for co-producing lactic acid and hydroxyacetone from Enteromorpha and its derived rhamnose according to claim 1, characterized in that: The catalyst is CeO2-R having a fish rod shape.

3. The method for co-producing lactic acid and hydroxyacetone from Enteromorpha and its derived rhamnose according to claim 2, characterized in that: The preparation method of CeO2-R is: A certain amount of Ce precursor Ce(NO3)3·6H2O was dissolved in 100 mL of water and ultrasonically stirred for 10 min to dissolve and disperse the Ce component. Then 24 g of NaOH was quickly added and the mixture was transferred to a hydrothermal reactor. The rotation speed was set to 200 rpm, the reaction temperature was set to 100°C, and the reaction time was set to 24 h. After the reaction, the obtained solid was filtered, washed, and dried, and calcined in a tubular furnace in an air atmosphere at 450°C, 5°C / min, for 3 h to obtain CeO2-R with a fish rod shape.

4. The method for co-producing lactic acid and hydroxyacetone from Enteromorpha and its derived rhamnose according to claim 1, characterized in that: The filtered solid catalyst was placed in an oven and dried at 80 °C for 10 h, then placed in a tubular furnace in an air atmosphere and calcined at 450 °C for 3 h, and can be reused.

5. The method for co-producing lactic acid and hydroxyacetone from Enteromorpha and its derived rhamnose according to claim 1, characterized in that: The reaction temperature is 180°C.

6. The method for co-producing lactic acid and hydroxyacetone from Enteromorpha and its derived rhamnose according to claim 1, characterized in that: The reaction time is 60 min.

7. The method for co-producing lactic acid and hydroxyacetone from Enteromorpha and rhamnose derived therefrom according to claim 1, characterized in that: The catalyst is 100 parts.

8. The method for co-producing lactic acid and hydroxyacetone from Enteromorpha and rhamnose derived therefrom according to claim 1, characterized in that: The substrate may be replaced by a C3 intermediate.