Lactic acid production method and sugar production method for lactic acid production

Abstract

To provide a lactic acid from a biomass feedstock, in a short time and at high yield.SOLUTION: A lactic acid production method comprises: a heating and pulverizing step for simultaneously executing heating and pulverizing to a biomass feedstock including cellulose or the like, and adding water to the heated and pulverized object for acquiring water soluble polysaccharide. The acquired water soluble polysaccharide is subjected to catalytic reaction for generating a lactic acid. By decomposing insoluble biomass feedstock to the water soluble polysaccharide and then subjecting the same to a reaction by using a catalyst, the lactic acid can be acquired in a short time and at high yield.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This specification discloses a method for producing lactic acid and a method for producing sugar for use in producing lactic acid. [Background technology]

[0002] Conventionally, known methods for producing lactic acid include catalytically reacting biomass materials containing cellulose or the like to obtain lactic acid. For example, Patent Document 1 discloses a method for producing lactic acid by adding an aqueous solvent or the like to a carbohydrate material such as cellulose in the presence of a Group III metal salt that acts as a Lewis acid catalyst, and heating the resulting mixture in the absence of oxygen. Patent Document 2 also discloses a method for producing lactic acid by heat-treating a carbohydrate-containing material in a solvent containing water or alcohol using a tin-containing compound as a catalyst. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-120796 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-97007 Summary of the Invention [Problem to be solved by the invention]

[0004] In the method for producing lactic acid described in Patent Document 1, when Yb(OTf)3 is used as the catalyst, the reaction time is as fast as 16 minutes, but the lactic acid yield is as low as 25%, and the catalyst is expensive. In the method for producing lactic acid described in Patent Document 2, when SnCl2 is used as the catalyst, the lactic acid (methyl lactate) yield is 59%, but the reaction time is long at 5 hours. As such, no conventional method for producing lactic acid satisfies both the reaction time and the lactic acid yield, and it is desirable to obtain lactic acid in a shorter time and with a higher yield.

[0005] The main purpose of the disclosed method for producing lactic acid and method for producing sugar for use in producing lactic acid is to obtain lactic acid from biomass raw materials in a short time and at a high yield. [Means for solving the problem]

[0006] The method for producing lactic acid and the method for producing sugar for producing lactic acid of the present disclosure employ the following measures to achieve the above-mentioned main object.

[0007] The method for producing lactic acid disclosed herein includes: A method for producing lactic acid from a biomass raw material containing cellulose, a heating and pulverizing step of performing a heating and pulverizing treatment on the biomass raw material simultaneously; a catalytic reaction step of converting the liquid obtained by adding water after the heating and grinding step into lactic acid through a catalytic reaction; The gist of the project is to provide the following:

[0008] In the method for producing lactic acid disclosed herein, a biomass feedstock is subjected to a heating and grinding process in which heating and grinding are performed simultaneously. After the heating and grinding process, water is added to the resulting liquid, which is then converted into lactic acid through a catalytic reaction. By breaking down the insoluble biomass feedstock into water-soluble sugars through the heating and grinding process, lactic acid can be obtained through the catalytic reaction in a short time and at a high yield.

[0009] Here, the heat-pulverization is carried out under conditions necessary to decompose insoluble biomass raw materials into water-soluble sugars, and is preferably carried out at a temperature of 120°C or higher. Furthermore, when a ball mill is used as the heat-pulverizer, it is more preferable to heat-pulverize so that the impact force (N) per ball multiplied by the required time (sec) is 47 or more, or to heat-pulverize so that the relative centrifugal acceleration of the balls is 140 G or more and 230 G or less. Furthermore, the catalytic reaction step may be carried out by adding water after the heat-pulverization step, performing solid-liquid separation, and catalytically reacting the resulting liquid to convert it into lactic acid.

[0010] The method for producing sugar for lactic acid production disclosed herein includes: A sugar production method for producing sugar for producing lactic acid from a biomass raw material containing cellulose or the like, a heating and pulverizing step of performing a heating and pulverizing treatment on the biomass raw material simultaneously; a water-adding step of adding water after the heating and grinding step to obtain a liquid containing water-soluble sugars; The gist of the project is to provide the following:

[0011] In the method for producing sugar for lactic acid production disclosed herein, a biomass feedstock is subjected to a heating and grinding process in which heating and grinding are performed simultaneously. After the heating and grinding process, water is added to produce a liquid containing water-soluble sugars. Lactic acid can be obtained in a short time and with a high yield by catalytically reacting this liquid. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a process diagram illustrating a process for producing lactic acid according to an embodiment of the present invention. [Figure 2] FIG. 1 is an explanatory diagram showing an example of the relationship between heat-pulverization of cellulose (avicel) and the solubilization rate, using experimental data. [Figure 3] FIG. 1 is an explanatory diagram showing an example of the relationship between the rotation speed of a heating mill, the grinding time, and the solubilization rate, using experimental data. [Figure 4] FIG. 1 is an explanatory diagram showing, using experimental data, an example of the relationship between the rotation speed of a heating mill, the peak solubilization rate, and the grinding time required to reach the peak. [Figure 5] FIG. 10 is an explanatory diagram showing an example of the relationship between the rotation speed of a heating crusher and impact force x time. [Figure 6] This is an explanatory diagram showing data on impact force [N], grinding time (minutes, seconds), impact force × time [N·S], peak solubilization rate [%], and relative centrifugal acceleration [G] at each rotation speed of the heating grinder. [Figure 7] FIG. 1 is a process diagram showing a process for producing lactic acid according to another embodiment. [Figure 8] FIG. 1 is an explanatory diagram showing an example of the relationship between the rotation speed of a heating mill, the grinding time, and the solubilization rate, using experimental data. [Figure 9] FIG. 1 is an explanatory diagram showing experimental data on the rotation speed of a heating grinder, grinding time, and sugar residual rate in the liquid and residue. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, an embodiment of the present disclosure will be described.

[0014] FIG. 1 is a flow chart illustrating an example of a process for producing lactic acid according to the present embodiment. In the method for producing lactic acid according to the present embodiment, first, cellulose (general formula (CH 10 O5) n The biomass raw material, including materials such as cellulose, cellulose acetate, cellulose nitrate, cellulose nitrate, cellulose nitrate, cellulose acetate, cellulose acetate nitrate ...

[0015] Next, water is added to the heated and pulverized sample (biomass feedstock), and the mixture is thoroughly stirred for solid-liquid separation. The liquid extracted contains water-soluble polysaccharides composed of glucose. The extracted liquid is then reacted with a catalyst (isomerization reaction, retroaldol reaction) to obtain lactic acid. By decomposing the insoluble biomass feedstock into water-soluble polysaccharides and then reacting them with a catalyst, lactic acid can be obtained in a short time and with a high yield. Examples of the catalyst include liquid catalysts that act as Lewis acids, such as AlCl3-SnCl2 and Yb(OTf)3. In this example, AlCl3-SnCl2 was used, and the reaction conditions were a reaction temperature of 190°C and a reaction pressure of 3 MPa. The catalyst can be any catalyst capable of obtaining lactic acid from water-soluble polysaccharides through a catalytic reaction. This is not limited to liquid catalysts; solid catalysts such as ZrO2 can also be used.

[0016] Figure 2 shows an example of the relationship between heat-pulverization and solubilization rate of cellulose (avicel). These experimental data were obtained by heat-pulverizing 0.3 g of cellulose (avicel) at different temperatures using a planetary ball mill. The solubilization rate was measured against the pulverization time at each temperature. In the figure, the solid line with open circles represents data obtained when heat-pulverized at 100°C, the solid line with triangles represents data obtained when heat-pulverized at 110°C, the solid line with diamonds represents data obtained when heat-pulverized at 120°C, the solid line with squares represents data obtained when heat-pulverized at 130°C, the solid line with inverted triangles represents data obtained when heat-pulverized at 150°C, the solid line with crosses represents data obtained when heat-pulverized at 170°C, and the solid line with black circles represents data obtained when heat-pulverized at 200°C. Heat-pulverization was performed using 75 g zirconia balls at a rotation speed of 300 rpm. As shown in Figure 2, in the case of cellulose (avicel), a high solubilization rate can be obtained in a short time by heat-pulverizing at 120°C, 130°C, 150°C, 170°C, or 200°C. This indicates that heat-pulverizing at a temperature of 120°C or higher is preferable.

[0017] Figure 3 is an explanatory diagram showing an example of the relationship between the rotation speed of the heat-milling machine, grinding time, and solubilization rate using experimental data. Figure 4 is an explanatory diagram showing an example of the relationship between the rotation speed of the heat-milling machine, the solubilization rate peak, and the grinding time required to reach the peak using experimental data. These experimental data were obtained by heat-milling cellulose (avicel) at different rotation speeds using a uniaxial ball mill, and measuring the solubilization rate versus grinding time for each rotation speed. In Figure 3, the solid line with circles represents data obtained when heat-milling was performed at 1000 rpm, the solid line with triangles represents data obtained when heat-milling was performed at 1100 rpm, the solid line with diamonds represents data obtained when heat-milling was performed at 1200 rpm, the solid line with squares represents data obtained when heat-milling was performed at 1300 rpm, and the solid line with inverted triangles represents data obtained when heat-milling was performed at 1400 rpm. Heat-milling was performed at 200°C for all rotation speeds. As shown in Figures 3 and 4, the solubilization rate peak is higher when heated and milled at 1100 rpm, 1200 rpm, or 1300 rpm than when heated and milled at 1000 rpm. Furthermore, the milling time required to reach the solubilization rate peak is shorter when heated and milled at 1200 rpm than when heated and milled at 1100 rpm, and shorter when heated and milled at 1300 rpm than when heated and milled at 1200 rpm. That is, as the rotation speed increases up to 1300 rpm, the milling time is shortened while still achieving a high solubilization rate. On the other hand, when heated and milled at 1400 rpm, the solubilization rate peak is lower than when heated and milled at 1000 rpm. After the peak, the solubilization rate further decreases over time. These findings suggest that the rotation speed for heating and milling is preferably between 1000 rpm and 1300 rpm, particularly between 1100 rpm and 1300 rpm.

[0018] Furthermore, we investigated the relationship between the rotation speed of the thermal grinder (1000 rpm to 1600 rpm in 100 rpm increments) and the peak solubilization rate at each rotation speed. The impact force, impact force × time, and ball acceleration (relative centrifugal acceleration) exerted on the raw material by a single ball were also investigated. Figure 5 shows an example of the relationship between the rotation speed of the thermal grinder and impact force × time. Figure 6 shows the data for impact force [N], grinding time (minutes, seconds), impact force × time [N·s], peak solubilization rate [%], and relative centrifugal acceleration [G] at each rotation speed of the thermal grinder. At rotation speeds of 1300 rpm, 1200 rpm, and 1100 rpm, where good peak solubilization rates of 86.7%, 86.6%, and 87%, respectively, the impact force × time [N·s] at which the solubilization rate peaked was 48.0, 49.1, and 51.6, respectively. The relative centrifugal accelerations at that time were 219, 187, and 157, respectively. From these results, it can be seen that the impact force × time [N·s] per ball during heating and grinding should preferably be 47 or more, and the acceleration (relative centrifugal acceleration) should preferably be 150G or more and 230G or less.

[0019] In the method for producing lactic acid according to the embodiment described above, biomass material containing cellulose and the like is subjected to heating and pulverization simultaneously, and lactic acid is produced by catalytically reacting the liquid obtained by adding water to the heated and pulverized material. By decomposing the insoluble biomass material into water-soluble polysaccharides by heating and pulverization, lactic acid can be produced by catalytic reaction in a short time and at a high yield.

[0020] In the above-described embodiment, lactic acid is obtained by adding water after the heating and grinding process, performing solid-liquid separation, and reacting the extracted liquid with a catalyst. However, as shown in FIG. 7, the solid-liquid separation process may be omitted, and lactic acid may be produced by adding water after the heating and grinding process and reacting the resulting mixture with a catalyst. FIG. 8 is an explanatory diagram showing an example of the relationship between the rotation speed of the heating and grinding machine, grinding time, and solubilization rate using experimental data. FIG. 9 is an explanatory diagram showing experimental data on the rotation speed of the heating and grinding machine, grinding time, and sugar residual rate in the liquid and residue. The data in FIG. 8 includes data obtained by heating and grinding at 1200 rpm and 1400 rpm shown in FIG. 3 above, as well as data obtained by heating and grinding at 1600 rpm. In this experimental example, when heating and grinding at 1600 rpm, the rotation speed was limited to 800 rpm due to overload. Figure 9 shows the residual sugar percentages in the liquid and residue obtained by adding water to the heat-milled sample and separating it into solid and liquid phases, for each of the circled points (rotation speed and time) in Figure 8. As shown in Figure 9, when heat-milling was performed at 1200 rpm, the residual sugar percentages in the liquid and residue were high (90% and 96%). On the other hand, when heat-milling was performed at 1400 rpm, the residual sugar percentages in the liquid and residue were high (100%), but low (54%). Furthermore, when heat-milling was performed at 1600 rpm, the residual sugar percentages in the liquid and residue were lower at the time (0.43 h) when the solubilization rate peaked compared to when heat-milling was performed at 1200 rpm. After the peak of solubilization, the residual sugar percentages in the liquid and residue were significantly lower. Based on these experimental data, it is believed that when heated and pulverized at 1200 rpm, lactic acid can be obtained by reacting not only the liquid extracted by solid-liquid separation from the heated and pulverized biomass material and the addition of water, but also the residue, with a catalyst. Therefore, the yield of lactic acid can be further increased by omitting the solid-liquid separation step and reacting the heated and pulverized biomass material with the addition of water.

[0021] Although the above-described embodiment has been described as a method for producing lactic acid, it may also be a method for producing sugar (a liquid containing a water-soluble polysaccharide) for use in producing lactic acid.

[0022] The above describes the forms for implementing the present disclosure, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0023] The present disclosure is applicable to the lactic acid production industry and the like.

Claims

1. A method for producing lactic acid from a biomass raw material containing cellulose, a heating and pulverizing step of performing a heating and pulverizing treatment on the biomass raw material simultaneously; a catalytic reaction step of converting the liquid obtained by adding water after the heating and grinding step into lactic acid through a catalytic reaction; Equipped with The heating and pulverizing step is a step of heating and pulverizing the mixture using a ball mill as a heating and pulverizing machine so that the relative centrifugal acceleration of the balls is 140 G or more and 230 G or less. A method for producing lactic acid.

2. The method for producing lactic acid according to claim 1, The heating and grinding step is carried out at a temperature of 120°C or higher. Lactic acid production method.

3. 3. The method for producing lactic acid according to claim 1 or 2, The heating and pulverizing step is a step of heating and pulverizing using a ball mill as a heating and pulverizing machine so that the value obtained by multiplying the impact force (N) per ball by the required time (sec) is 47 or more. Lactic acid production method.

4. The method for producing lactic acid according to any one of claims 1 to 3, The catalytic reaction step is a step of converting the liquid obtained by adding water and performing solid-liquid separation after the heating and grinding step into lactic acid through a catalytic reaction. Lactic acid production method.

5. A sugar production method for producing sugar for producing lactic acid from a biomass raw material containing cellulose or the like, a heating and pulverizing step of performing a heating and pulverizing treatment on the biomass raw material simultaneously; a water-adding step of adding water after the heating and grinding step to obtain a liquid containing water-soluble sugars; Equipped with The heating and pulverizing step is a step of heating and pulverizing the mixture using a ball mill as a heating and pulverizing machine so that the relative centrifugal acceleration of the balls is 140 G or more and 230 G or less. A method for producing sugar for use in lactic acid production.

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