METHOD FOR PRODUCING LACTIC ACID FROM WASTE PAPER USING LANTHANIDE-BASED METAL CATALYST

Abstract

Disclosed are a method for producing lactic acid from wastes containing cellulose and/or hemicellulose and a catalyst for thermochemical conversion reaction of wastes containing cellulose and/or hemicellulose. The method includes a step of adding a metal catalyst to wastes containing cellulose and/or hemicellulose and performing thermochemical conversion reaction. The method provides an effect of producing lactic acid from discarded wastes, e.g., waste paper such as waste corrugated paperboards, waste paper boxes, waste newspapers, etc.

Claims

1. A catalyst for thermochemical conversion reaction of wastes comprising cellulose and/or hemicellulose, which comprises a lanthanide metal.

2. The catalyst for thermochemical conversion reaction of wastes according to claim 1, wherein the wastes are waste paper.

3. The catalyst for thermochemical conversion reaction of wastes according to claim 1, wherein the lanthanide metal comprises a lanthanide triflate metal.

4. The catalyst for thermochemical conversion reaction of wastes according to claim 3, wherein the lanthanide triflate metal is one or more selected from a group consisting of lanthanum triflate, cerium triflate, praseodymium triflate, neodymium triflate, promethium triflate, samarium triflate, europium triflate, gadolinium triflate, terbium triflate, dysprosium triflate, holmium triflate, erbium triflate, thulium triflate, ytterbium triflate and lutetium triflate.

5. The catalyst for thermochemical conversion reaction of wastes according to claim 1, wherein the catalyst is mixed in an amount of 0.25-0.5 mmol per 1 g of the wastes.

6. The catalyst for thermochemical conversion reaction of wastes according to claim 1, wherein the catalyst is mixed with a mixture of the wastes and a solvent.

7. The catalyst for thermochemical conversion reaction of wastes according to claim 1, wherein lactic acid is produced from the wastes containing cellulose and/or hemicellulose by the thermochemical conversion reaction.

8. The catalyst for thermochemical conversion reaction of wastes according to claim 1, wherein the thermochemical conversion reaction is performed at 200-300° C.

9. The catalyst for thermochemical conversion reaction of wastes according to claim 1, wherein the thermochemical conversion reaction is performed for 20-70 minutes.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0037] FIG. 1 schematically shows a process for producing lactic acid according to an exemplary embodiment of the present disclosure.

[0038] FIG. 2 shows lactic acid production yield depending on metal catalysts according to an exemplary embodiment of the present disclosure.

[0039] FIG. 3 shows lactic acid production yield depending on thermochemical conversion reaction temperature according to an exemplary embodiment of the present disclosure.

[0040] FIG. 4 shows lactic acid production yield depending on thermochemical conversion reaction time according to an exemplary embodiment of the present disclosure.

[0041] FIG. 5 shows lactic acid production yield depending on metal catalysts according to a comparative example.

BEST MODE

[0042] Hereinafter, the present disclosure is described in detail.

[0043] In an aspect, the present disclosure provides a method for producing lactic acid from wastes, which includes a step of adding a metal catalyst to wastes containing cellulose and/or hemicellulose.

[0044] In an exemplary embodiment, both L- and D-lactic acid may be produced by the method.

[0045] In an exemplary embodiment, the wastes may be waste paper and/or wood.

[0046] In an exemplary embodiment, the waste paper may be waste paper boxes, waste corrugated paperboards, waste newspapers, etc.

[0047] In an exemplary embodiment, the metal catalyst may include a lanthanide metal catalyst.

[0048] In an aspect, lactic acid can be produced from the carbohydrate components in the wastes in short time with high yield by using a lanthanide metal catalyst.

[0049] In an exemplary embodiment, the metal catalyst may include a lanthanide triflate metal catalyst.

[0050] In an exemplary embodiment, the lanthanide triflate metal catalyst may be one or more selected from a group consisting of lanthanum triflate, cerium triflate, praseodymium triflate, neodymium triflate, promethium triflate, samarium triflate, europium triflate, gadolinium triflate, terbium triflate, dysprosium triflate, holmium triflate, erbium triflate, thulium triflate, ytterbium triflate and lutetium triflate.

[0051] In an exemplary embodiment, the metal catalyst may be added in an amount of 0.25-0.5 mmol per 1 g of the wastes.

[0052] In an exemplary embodiment, the metal catalyst may be added after the wastes are mixed with a solvent.

[0053] In an exemplary embodiment, the solvent may include water.

[0054] In an exemplary embodiment, the thermochemical conversion reaction may be performed after the metal catalyst is added.

[0055] In an exemplary embodiment, the thermochemical conversion reaction may be performed under an inert atmosphere by supplying an inert gas.

[0056] In an exemplary embodiment, the inert gas may be nitrogen or helium.

[0057] In an exemplary embodiment, the inert gas may be supplied at room temperature at a pressure of 10-50 bar.

[0058] In an exemplary embodiment, the thermochemical conversion reaction may be performed at 200-300° C.

[0059] In another exemplary embodiment, the thermochemical conversion reaction may be performed at 200° C. or higher, 210° C. or higher, 220° C. or higher, 230° C. or higher, 240° C. or higher, 250° C. or higher, 260° C. or higher, 270° C. or higher, 280° C. or higher or 290° C. or higher, and 300° C. or lower, 290° C. or lower, 280° C. or lower, 270° C. or lower, 260° C. or lower, 250° C. or lower, 240° C. or lower, 230° C. or lower, 220° C. or lower or 210° C. or lower. For example, the thermochemical conversion reaction may be specifically performed at 200-275° C., 225-275° C., 225-250° C. or 250-275° C. in terms of the production yield of lactic acid.

[0060] In an exemplary embodiment, the thermochemical conversion reaction may be performed for 20-70 minutes.

[0061] In another exemplary embodiment, the thermochemical conversion reaction may be performed for 20 minutes or longer, 25 minutes or longer, 30 minutes or longer, 35 minutes or longer, 40 minutes or longer, 45 minutes or longer, 50 minutes or longer, 55 minutes or longer, 60 minutes or longer or 65 minutes or longer, and 70 minutes or shorter, 65 minutes or shorter, 60 minutes or shorter, 55 minutes or shorter, 50 minutes or shorter, 45 minutes or shorter, 40 minutes or shorter, 35 minutes or shorter, 30 minutes or shorter or 25 minutes or shorter. For example, the thermochemical conversion reaction may be performed for 25-65 minutes or 30-60 minutes in terms of the production yield of lactic acid.

[0062] In an exemplary embodiment, the thermochemical conversion reaction may be performed in a batch reactor.

[0063] In another aspect, the present disclosure provides a method for producing lactic acid from wastes, which includes: a step of adding waste paper including cellulose and/or hemicellulose, water and a lanthanide triflate catalyst into a reactor; a step of supplying an inert gas into the reactor; and a step of performing thermochemical conversion reaction by heating the reactor under inert atmosphere.

[0064] In another aspect, the present disclosure provides lactic acid produced by the method.

[0065] In another aspect, the present disclosure provides a catalyst for thermochemical conversion reaction of wastes containing cellulose and/or hemicellulose, which includes a lanthanide metal component and is used for producing lactic acid from wastes containing cellulose and/or hemicellulose.

[0066] In an exemplary embodiment, the lanthanide metal component may be lanthanide triflate.

[0067] In an exemplary embodiment, the lanthanide triflate may be one or more selected from a group consisting of lanthanum triflate, cerium triflate, praseodymium triflate, neodymium triflate, promethium triflate, samarium triflate, europium triflate, gadolinium triflate, terbium triflate, dysprosium triflate, holmium triflate, erbium triflate, thulium triflate, ytterbium triflate and lutetium triflate.

[0068] In an aspect, the catalyst allows production of lactic acid from wastes containing cellulose and/or hemicellulose with high yield and selectivity in short time. For example, the available sugars (glucose, xylose, etc.) contained in the raw material may be converted to lactic acid at an efficiency of about 60%.

[0069] Hereinafter, the present disclosure will be described more specifically through examples. The examples provided only for illustration of the present disclosure and it will be obvious to those having ordinary skill in the art that the scope of the present disclosure is not limited by the examples.

Example 1

[0070] A dried waste corrugated paperboard was cut to a size of 0.5 cm×0.5 cm. 200 mg of the prepared waste corrugated paperboard was added to a batch reactor after mixing well with 25 mL of water. Together with this, 0.05 mmol of one of lanthanum triflate (La(OTf).sub.3), neodymium triflate (Nd(OTf).sub.3), ytterbium triflate (Yb(OTf).sub.3), erbium triflate (Er(OTf).sub.3) catalysts was added and the reactor was filled with 30 bar of helium at room temperature. Then, after heating the reactor to 250° C., thermochemical conversion reaction was performed for 30 minutes while stirring at 300 rpm. After cooling the reactor again to room temperature, the yield of lactic acid was calculated from the liquid reaction product according to the following equation.

Yield of lactic acid(mol %)=(Produced lactic acid (mol))/[(2×C.sub.6 monosaccharides in raw material (mol))+(C.sub.5 monosaccharides in raw material (mol))]×100

[0071] FIG. 2 shows a result of quantifying the lactic acid produced through the thermochemical conversion reaction. It was confirmed that lactic acid was obtained with a yield of about 55-66 mol % based on the cellulose- and hemicellulose-derived monosaccharides in the waste corrugated paperboard.

Example 2

[0072] Thermochemical conversion reaction was performed in the same manner as in Example 1, except that erbium triflate (Er(OTf).sub.3) was used as a catalyst and the thermochemical conversion reaction temperature was varied from 200 to 275° C.

[0073] The result of analyzing the yield of lactic acid is shown in FIG. 3. As seen from FIG. 3, the yield of lactic acid was about 40 mol % or higher when the thermochemical conversion reaction was performed at 225-275° C. The highest lactic acid yield was achieved when the thermochemical conversion reaction was performed at 250° C.

Example 3

[0074] Thermochemical conversion reaction was performed in the same manner as in Example 1, except that erbium triflate (Er(OTf).sub.3) was used as a catalyst and the thermochemical conversion reaction time was varied from 30 minutes to 1 hour.

[0075] The result of analyzing the yield of lactic acid is shown in FIG. 4. As seen from FIG. 4, the highest lactic acid yield was achieved when the thermochemical conversion reaction was performed for 30 minutes.

Comparative Example 1

[0076] Thermochemical conversion reaction was performed in the same manner as in Example 1, except that zinc chloride (ZnCl.sub.2), which is a commonly used Lewis acid catalyst, was used as a catalyst and the thermochemical conversion reaction temperature was performed at 250° C. for 30 minutes.

[0077] The result of analyzing the yield of lactic acid is shown in FIG. 5. As seen from FIG. 5, when thermochemical conversion reaction was performed using the zinc chloride Lewis acid catalyst instead of the lanthanide metal catalyst, lactic acid was produced at a yield of about 23 mol %.

Comparative Example 2

[0078] Thermochemical conversion reaction was performed in the same manner as in Example 1, except that aluminum chloride (AlCl.sub.2), which is a commonly used Lewis acid catalyst, was used as a catalyst and the thermochemical conversion reaction temperature was performed at 250° C. for 30 minutes.

[0079] The result of analyzing the yield of lactic acid is shown in FIG. 5. As seen from FIG. 5, when thermochemical conversion reaction was performed using the aluminum chloride Lewis acid catalyst instead of the lanthanide metal catalyst, lactic acid was produced at a yield of about 5 mol %.

Comparative Example 3

[0080] Thermochemical conversion reaction was performed in the same manner as in Example 1, except that zinc triflate (Zn(OTf).sub.2) was used as a catalyst and the thermochemical conversion reaction was performed at 250° C. for 30 minutes.

[0081] The result of analyzing the yield of lactic acid is shown in FIG. 5. As seen from FIG. 5, when thermochemical conversion reaction was performed using the zinc triflate catalyst containing zinc metal instead of the lanthanide metal catalyst, lactic acid was produced at a yield of about 39 mol %.

[0082] As described above, it was confirmed that the yield of lactic acid was significantly lower when the Lewis acid catalyst or the zinc triflate catalyst was used in Comparative Example 1-3 as compared to when the lanthanide metal catalyst was used under the same condition. Accordingly, it was confirmed that the yield of lactic acid can be increased effectively by using the lanthanide metal catalyst when producing lactic acid from wastes through thermochemical conversion reaction.

[0083] While specific exemplary embodiments of the present disclosure have been described in detail above, it will be obvious to those having ordinary knowledge in the art that the foregoing description is given only as specific exemplary embodiments and the scope of the present disclosure is not limited thereby. It is to be noted that the substantial scope of the present disclosure is defined by the appended claims and their equivalents.