Method for purifying xylose from xylose mother liquor by using calcium type resin and sulfuric acid type resin

Abstract

The invention belongs to the technical field of sugar alcohol preparation, and relates to a method for purifying xylose from xylose mother liquor by using calcium type resin and sulfuric acid type resin, which comprises the following steps: diluting the raw material xylose mother liquor with the refractive index of 65-70% until the refractive index is 50-60%, adding ash for carbonation, filtering by a vacuum rotary drum, and filtering by a plate frame to obtain pretreatment liquid; performing primary chromatographic separation treatment on the pretreatment solution to obtain a first extracting solution, wherein sulfuric acid type chromatographic resin is used in the primary chromatographic separation treatment; carrying out refining treatment on the first extracting solution to obtain a refined solution, carrying out evaporation concentration, crystallization and centrifugal treatment on the refined solution to obtain moist sugar and centrifugal mother liquor, and drying the moist sugar to obtain a xylose finished product; the centrifugal mother liquor is subjected to second-time chromatographic separation treatment, a second extracting solution obtained through separation is mixed into the first extracting solution, and calcium type chromatographic resin is used for second-time chromatographic separation treatment. Sulfuric acid type chromatographic resin and calcium type chromatographic resin are adopted for cooperative treatment, separation of all components in the centrifugal mother liquor is improved, and therefore the separation efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of sugar alcohol preparation technology, and specifically relates to a method for purifying xylose from xylose mother liquor using calcium-type resin and sulfate-type resin. Background Technology

[0002] Xylose mother liquor is a byproduct remaining after xylose extraction from corn cob hydrolysate, and is often sold as a low-value byproduct. The xylose content in the mother liquor is 40-50%, giving it some recovery value. Currently, there is considerable research on the high-value applications of xylose mother liquor. For example, patent application number CN201811429458.3 discloses a method for preparing xylitol and mixed syrup from xylose mother liquor. This method uses chromatographic separation technology to enrich the xylose component in the mother liquor into the extract, achieving a content of 80%. After concentration and crystallization, the extract is used to produce raw xylose for xylitol production. Another example is patent application number CN202110568200.7, which discloses a system and method for preparing refined xylose using chromatographic extract from xylose mother liquor. This method uses a chromatographic separation system to purify the mother liquor, concentrate and crystallize it to obtain raw xylose, and then re-dissolve and refine the raw xylose to obtain higher-value refined xylose. However, none of the relevant patents involve methods for treating the centrifuged mother liquor.

[0003] Centrifugation mother liquor is a byproduct remaining after recrystallizing the extract from chromatographic separation to extract xylose. It contains 40-50% xylose and is typically returned to the raw material end for further chromatographic separation. However, since the centrifugation mother liquor has already undergone one chromatographic separation, the separation degree of each component is reduced, increasing the difficulty of separation. With each re-extraction, the separation efficiency of the chromatography gradually decreases, increasing production costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for purifying xylose from xylose mother liquor using calcium-type resin and sulfuric acid-type resin. The method employs the synergistic treatment of sulfuric acid-type chromatographic resin and calcium-type chromatographic resin, and improves the separation of each component in the centrifuged mother liquor by changing the type of chromatographic resin, thereby increasing the separation efficiency.

[0005] This invention is achieved by providing a method for purifying xylose from xylose mother liquor using calcium-type resin and sulfate-type resin, comprising the following steps: Step 1: Pretreatment. The raw xylose mother liquor with a refractive index of 65-70% is diluted to a refractive index of 50-60%. After saturation treatment with ash addition, vacuum drum filtration treatment, and plate and frame filtration treatment, the pretreated liquid is obtained. Step 2: Chromatographic separation. The pretreated solution is subjected to a first chromatographic separation process to obtain the first extract. The separation resin used in the first chromatographic separation process is a sulfuric acid type chromatographic resin. Step 3: Refining. The first extract is subjected to decolorization and ion exchange treatments to obtain a refined extract. Step 4: Crystallization and centrifugation. The refined liquid is then subjected to evaporation and concentration, crystallization and centrifugation in sequence to obtain hygroscopic sugar and centrifugation mother liquor. The hygroscopic sugar is dried and processed into xylose product. Step 5: Perform a second chromatographic separation on the centrifuged mother liquor, mix the second extract obtained from the separation with the first extract obtained in step 2, and then proceed to step 3 for purification; wherein, the separation resin used in the second chromatographic separation is calcium-type chromatographic resin.

[0006] Furthermore, in step 1, the filtration rate of the pretreatment liquid is tested. Only pretreatment liquid that passes the filtration rate test is allowed to proceed to step 2. The filtration rate testing method is as follows: 200 ml of pretreatment liquid is filtered through a 0.80 micrometer filter membrane, and the filtration time is less than 3 minutes, which is considered qualified.

[0007] This invention addresses the challenge of separating the centrifuged mother liquor during the chromatographic extraction of xylose from the mother liquor. The main reason for this difficulty is that the separation degree of each component in the centrifuged mother liquor gradually decreases with the increasing number of times it is returned to the chromatogram. Therefore, improving the separation efficiency of the centrifuged mother liquor requires improving the separation degree of each component during the chromatographic separation process.

[0008] Compared with the prior art, the method of purifying xylose from xylose mother liquor using calcium-type resin and sulfate-type resin of the present invention has the following advantages: 1. By using synergistic treatment with different types of chromatographic separation resins, the separation efficiency of the centrifuged mother liquor and the xylose content of the extract can be improved. 2. By processing the centrifuged mother liquor and the raw xylose mother liquor separately, the separation efficiency of the raw xylose mother liquor can be improved; 3. By supplementing the calcium-type resin in chromatographic separation, the amount of sulfuric acid-type resin used in chromatographic separation can be reduced, thereby reducing fixed asset investment. Attached Figure Description

[0009] Figure 1 This is a schematic diagram illustrating the process principle of a preferred embodiment of the present invention.

[0010] The arrows in the diagram indicate the flow direction of various materials. Detailed Implementation

[0011] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0012] Please refer to Figure 1 As shown, a preferred embodiment of the method for purifying xylose from xylose mother liquor using calcium-type resin and sulfate-type resin of the present invention includes the following steps: Step 1: Pretreatment. Dilute the raw xylose mother liquor with a refractive index of 65-70% to 50-60%. After saturation treatment with ash addition, vacuum drum filtration, and plate and frame filtration, a pretreated solution is obtained. Filter 200ml of the pretreated solution through a 0.80-micron filter membrane. If the filtration time is less than 3 minutes, the pretreated solution is qualified and proceeds to Step 2; otherwise, replace with another batch of raw xylose mother liquor and repeat Step 1.

[0013] Step 2: Chromatographic separation. The pretreated solution is subjected to the first chromatographic separation process to obtain the first extract. The separation resin used in the first chromatographic separation process is a sulfuric acid type chromatographic resin.

[0014] Step 3: Refining. The first extract is subjected to decolorization and ion exchange treatments to obtain a refined extract.

[0015] Step 4: Crystallization and centrifugation. The refined liquid is then subjected to evaporation and concentration, crystallization and centrifugation in sequence to obtain hygroscopic sugar and centrifugation mother liquor. The hygroscopic sugar is then dried and processed into xylose product.

[0016] Step 5: Perform a second chromatographic separation on the centrifuged mother liquor, mix the second extract obtained from the separation with the first extract obtained in step 2, and then proceed to step 3 for purification; wherein, the separation resin used in the second chromatographic separation is calcium-type chromatographic resin.

[0017] The following specific examples and comparative examples further illustrate the method of purifying xylose from xylose mother liquor using calcium-type resin and sulfate-type resin.

[0018] Example 1

[0019] The method for purifying xylose from xylose mother liquor using calcium-type resin and sulfate-type resin of the present invention includes the following steps: Step 11: Dilute the raw xylose mother liquor with a refractive index of 66% and a xylose content of 45.6% to a refractive index of 50-60% with water; then add calcium hydroxide and carbon dioxide for flocculation and precipitation. The resulting suspension is then subjected to vacuum drum filtration and plate and frame filtration to obtain a pretreated solution. The filtration rate of the pretreated solution is tested. 200ml of the pretreated solution is filtered through a 0.80-micron filter membrane, and the filtration time is less than 3 minutes.

[0020] Step 12: After heating the pretreatment solution to 60°C, it is subjected to the first chromatographic separation process using a sulfuric acid type resin chromatographic separation system to obtain the first extract. The xylose content of the first extract is 76.5%, and the xylose content of the retrieval solution is 9.2%. The xylose recovery rate in this step is 91.2%.

[0021] Step 13: The first extract is concentrated in an evaporator to a refractive index of 40% and then enters the decolorization process. Under the adsorption of activated carbon, the transmittance is increased to over 90% and then enters the ion exchange process. The pH of the ion exchange effluent is controlled to be greater than 3.5 and the conductivity to be less than 50 μS / cm to obtain the purified liquid.

[0022] Step 14: After the refined liquid is concentrated to 80-85% by an evaporator, it enters the crystallization process and the centrifugation process. The centrifugation process separates the molten sugar and the centrifugation mother liquor. The molten sugar has a xylose content of 99.2% and the centrifugation mother liquor has a xylose content of 46%. The molten sugar is dried and processed into xylose product. The centrifugation yield of this process is 48.1%.

[0023] Step 15: The centrifuged mother liquor is fed into a chromatographic separation system using calcium-type resin for a second chromatographic separation process. The resulting second extract is mixed with the first extract obtained in step 12 and reused. The xylose purity of the second extract is 74.2%, and the xylose recovery rate in this step is 90%.

[0024] Comparative Example 1 The first comparative example of this invention includes the following steps: Step D11: Mix the raw xylose mother liquor (66% refractive index, 45.6% xylose content) with the centrifuged mother liquor (65% refractive index, 46% xylose content) at a mass ratio of 2:1, and dilute with water to a refractive index of 50-60%. Then add calcium hydroxide and carbon dioxide for flocculation and precipitation. The resulting suspension is then subjected to vacuum drum filtration and plate and frame filtration to obtain a pretreated solution. The filtration rate of the pretreated solution is tested. 200 ml of the pretreated solution is filtered through a 0.80 micron filter membrane, and the filtration time is less than 3 minutes.

[0025] Step D12: After the pretreatment solution is heated to 60°C, it is subjected to the first chromatographic separation process using a sulfuric acid type resin to obtain the first extract. The xylose content of the first extract is 73.2%, and the xylose content of the residue is 16.3%. The xylose recovery rate in this step is 88.0%.

[0026] Step D13: The first extract is concentrated in an evaporator to a refractive index of 40% and then enters the decolorization process. Under the adsorption of activated carbon, the transmittance is increased to over 90% and then enters the ion exchange process. The pH of the ion exchange effluent is controlled to be greater than 3.5 and the conductivity to be less than 50 μS / cm to obtain the purified liquid.

[0027] Step D14: After the refined liquid is concentrated to 80-85% by an evaporator, it enters the crystallization and centrifugation processes. Centrifugation separates the molten sugar and the mother liquor. The molten sugar is then dried and processed into xylose product. The molten sugar has a xylose content of 98.8%, and the mother liquor has a xylose content of 48%. The centrifugation yield of this process is 46.5%.

[0028] Comparative Example 2 The second comparative example of the present invention includes the following steps: Step D21: Mix the raw xylose mother liquor (66% refractive index, 45.6% xylose content) with the centrifuged mother liquor (65% refractive index, 46% xylose content) at a mass ratio of 3:1, and dilute with water to a refractive index of 50-60%. Then add calcium hydroxide and carbon dioxide for flocculation and precipitation. The resulting suspension is then subjected to vacuum drum filtration and plate and frame filtration to obtain a pretreated solution. The filtration rate of the pretreated solution is tested. 200 ml of the pretreated solution is filtered through a 0.80 micron filter membrane, and the filtration time is less than 3 minutes.

[0029] Step D22: After the pretreatment solution is heated to 60°C, it is subjected to the first chromatographic separation process using a sulfuric acid type resin to obtain the first extract. The xylose content of the first extract is 74.2%, and the xylose content of the residue is 14.5%. The xylose recovery rate in this step is 89.2%.

[0030] Step D23: The first extract is concentrated in an evaporator to a refractive index of 40% and then enters the decolorization process. Under the adsorption of activated carbon, the transmittance is increased to over 90% and then enters the ion exchange process. The pH of the ion exchange effluent is controlled to be greater than 3.5 and the conductivity to be less than 50 μS / cm to obtain the purified liquid.

[0031] Step D24: After the refined liquid is concentrated to 80-85% by an evaporator, it enters the crystallization and centrifugation processes. Centrifugation separates the molten sugar and the mother liquor. The molten sugar is then dried and processed into xylose product. The molten sugar has a xylose content of 98.9%, and the mother liquor has a xylose content of 46%. The centrifugation yield of this process is 47.2%.

[0032] Comparative Examples 1 and 2 show that repeated refilling of the centrifuged mother liquor has an adverse effect on chromatographic separation, and the greater the mixing ratio, the greater the impact.

[0033] A comparison of Example 1 and Comparative Example 1 reveals that in existing processes, to maintain the balance of the centrifugal mother liquor, the mixing ratio of the raw xylose mother liquor and the centrifugal mother liquor is approximately 2:1. This results in a xylose recovery rate of only 88% and an extract purity of only about 73% during the chromatographic separation process. Centrifugation is difficult, washing time is long, and the centrifugation yield is only 46.5%, with the finished xylose product containing less than 99% xylose. However, by employing the synergistic effect of sulfuric acid-type resin and calcium-type chromatographic resin in this invention, the separation difficulties caused by repeated re-coating of the centrifugal mother liquor can be avoided. The xylose recovery rate during the chromatographic separation process is over 90%, an improvement of 2 percentage points compared to Comparative Example 1. The overall content of the extract is 75.7%, an increase of 2.7% compared to Comparative Example 1. The centrifugation yield is 48.1%, an increase of 1.6% compared to Comparative Example 1, and the finished xylose product has a xylose content of 99.2%, indicating a higher quality finished xylose product.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for purifying xylose from xylose mother liquor using calcium-type resin and sulfate-type resin, characterized in that, Includes the following steps: Step 1: Pretreatment. The raw xylose mother liquor with a refractive index of 65-70% is diluted to a refractive index of 50-60%. After saturation treatment with ash addition, vacuum drum filtration treatment, and plate and frame filtration treatment, the pretreated liquid is obtained. Step 2: Chromatographic separation. The pretreated solution is subjected to a first chromatographic separation process to obtain the first extract. The separation resin used in the first chromatographic separation process is a sulfuric acid type chromatographic resin. Step 3: Refining. The first extract is subjected to decolorization and ion exchange treatments to obtain a refined extract. Step 4: Crystallization and centrifugation. The refined liquid is then subjected to evaporation and concentration, crystallization and centrifugation in sequence to obtain hygroscopic sugar and centrifugation mother liquor. The hygroscopic sugar is dried and processed into xylose product. Step 5: Perform a second chromatographic separation on the centrifuged mother liquor, mix the second extract obtained from the separation with the first extract obtained in step 2, and then proceed to step 3 for purification; wherein, the separation resin used in the second chromatographic separation is calcium-type chromatographic resin.

2. The method for purifying xylose from xylose mother liquor using calcium-type resin and sulfate-type resin as described in claim 1, characterized in that, Step 1 also includes testing the filtration rate of the pretreatment liquid. Only pretreatment liquid that passes the filtration rate test will proceed to step 2. The filtration rate testing method is as follows: 200 ml of pretreatment liquid is filtered through a 0.80 micrometer filter membrane, and the filtration time is less than 3 minutes to be considered qualified.

3. The method for purifying xylose from xylose mother liquor using calcium-type resin and sulfate-type resin as described in claim 2, characterized in that, Includes the following steps: Step 11: Dilute the xylose mother liquor with a refractive index of 66% to 50-60% with water; then add calcium hydroxide and carbon dioxide for flocculation and precipitation. The resulting suspension is then subjected to vacuum drum filtration and plate and frame filtration to obtain a pretreated solution. The filtration rate of the pretreated solution is tested. 200ml of the pretreated solution is filtered through a 0.80-micron filter membrane, and the filtration time is less than 3 minutes. Step 12: After heating the pretreatment solution to 60°C, it is subjected to the first chromatographic separation process using a sulfuric acid type resin chromatographic separation system to obtain the first extract. Step 13: The first extract is concentrated in an evaporator to a refractive index of 40% and then enters the decolorization process. Under the adsorption of activated carbon, the transmittance is increased to over 90% and then enters the ion exchange process. The pH of the ion exchange effluent is controlled to be greater than 3.5 and the conductivity to be less than 50 μS / cm to obtain the purified liquid. Step 14: After the refined liquid is concentrated to 80-85% by an evaporator, it enters the crystallization process and the centrifugation process. The centrifugation process separates the molten sugar and the centrifugation mother liquor. The molten sugar is dried and then processed into xylose product. Step 15: The centrifuged mother liquor is fed into a chromatographic separation system using calcium-type resin for a second chromatographic separation process. The resulting second extract is then mixed with the first extract obtained in step 12 for reuse.

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