A method for extracting finished xylose from xylose mother liquor

Abstract

The present invention relates to a method for extracting finished xylose from a xylose mother liquor, comprising the following steps: the xylose mother liquor is a centrifugal liquid obtained during the extraction of xylose from a corncob hydrolyzate, is placed in an evaporator, evaporated and concentrated to a solid concentration of 85-95%, and the evaporator does not cause crystallization; the concentrated material enters a crystallization tank for cooling and crystallization; the crystallized material enters a centrifuge for centrifugal treatment to separate and obtain a centrifugal mother liquor and a centrifugal massecuite; the centrifugal massecuite is transported to a dissolving tank, water is added, stirred and dissolved into a sugar liquid with a refractive index of 60%; the centrifugal mother liquor is decolorized and subjected to a separation treatment in sequence; the separated material is subjected to chromatographic separation treatment to obtain a raffinate and an extract, respectively; the extract and the sugar liquid are added to a blending tank for blending to obtain a blending liquid with a xylose content of 70-75%, and the blending liquid is then refined and processed into finished xylose. The present invention reduces the difficulty of chromatographic resin separation, reduces the content of xylose in the effluent xylose mother liquor, and improves the xylose recovery rate.

Description

Technical Field

[0001] The invention belongs to the technical field of sugar alcohol preparation, and particularly relates to a method for extracting finished xylose from xylose mother liquor. Background Art

[0002] Xylose mother liquor is a byproduct of xylose extraction from corn cobs through pretreatment. It still contains a high xylose content, accounting for 40-50% of the dry matter, and has great recycling value. With the recent development of chromatographic separation technology, more and more companies have focused on recycling xylose mother liquor. Chromatographic separation is used to purify xylose mother liquor, thereby enabling xylose recovery. For example, patent application number CN201811429458.3 discloses a process for preparing xylitol and mixed sugar syrup from xylose mother liquor. Chromatographic separation is used to enrich the xylose components in the mother liquor into an extract, increasing the extract's content to 80%, thereby enabling xylose recovery. Due to the large purification range of this process, the chromatographic process must increase the xylose content from 40-50% to 80%. This places high demands on the separation capacity of the chromatographic resin, which is expensive to purchase. Furthermore, the cost of xylose mother liquor is relatively complex, resulting in significant contamination of the chromatographic resin, which significantly reduces the separation capacity of the chromatographic resin and increases the xylose content in the byproduct to 30%. Therefore, how to maximize the purification of xylose in xylose mother liquor while reducing the company's investment is an important direction for improving the company's competitiveness. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for extracting finished xylose from xylose mother liquor. In view of the problems of high separation capacity requirements, large investment and unstable performance of chromatographic resins in the reuse of xylose mother liquor, the xylose content standard of the chromatographic extract is lowered from 80% to 60-65% by combining a traditional centrifugation process with a chromatographic separation process, thereby reducing the difficulty of chromatographic resin separation, thereby facilitating a reduction in the xylose content in the discharged xylose mother liquor and improving the xylose recovery rate.

[0004] The present invention is achieved by providing a method for extracting finished xylose from xylose mother liquor, comprising the following steps:

[0005] Step 1: The xylose mother liquor is the centrifugal liquid obtained during the xylose extraction process of the corncob hydrolyzate. The xylose mother liquor is placed in an evaporator and evaporated and concentrated to a solid concentration of 85-95%, and the evaporator does not crystallize.

[0006] Step 2: The concentrated material enters the crystallization tank for cooling and crystallization;

[0007] Step 3: The crystallized material enters a centrifuge for centrifugation to separate the centrifuged mother liquor and the centrifuged massecuite;

[0008] Step 4: Transfer the centrifuged massecuite to a dissolving tank, add water and stir to dissolve into a sugar solution with a refractive index of 60% for later use;

[0009] Step 5: The centrifuged mother liquor is subjected to decolorization and decolorization treatment in sequence;

[0010] In the sixth step, the materials after the centrifugation are subjected to chromatographic separation to obtain a raffinate and an extract respectively;

[0011] In the seventh step, the extract and the sugar solution from step four are added to a blending tank for blending to obtain a blending solution with a xylose content of 70-75%. The blending solution is then refined and processed into finished xylose.

[0012] Compared with the prior art, the method of extracting finished xylose from xylose mother liquor of the present invention has the following advantages:

[0013] 1. By blending the purity of centrifugal massecuite, the xylose content standard of the chromatographic extract is reduced from the original 80% to 60-65%, which reduces the difficulty of chromatographic separation, expands the selection space of chromatographic resins, and helps reduce the procurement cost of chromatographic resins;

[0014] 2. The process is more stable, the efflux content can be stably controlled at around 10%, and the xylose recovery rate can reach more than 80%;

[0015] 3. Combined with the traditional centrifugation process to purify the xylose mother liquor, compared with the existing process, this process can reduce the chromatographic treatment requirements by 50%, thereby helping enterprises reduce one-time investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The figure is a schematic flow chart of the steps of a preferred embodiment of the method for extracting finished xylose from xylose mother liquor according to the present invention. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] Please refer to Figure 1 As shown in the figure, the direction indicated by the arrow is the flow direction of the material. A preferred embodiment of the method for extracting finished xylose from xylose mother liquor of the present invention comprises the following steps:

[0019] Step 1: The xylose mother liquor is the centrifugal liquid obtained during the process of extracting xylose from the corncob hydrolyzate. The xylose mother liquor is placed in an evaporator and evaporated and concentrated to a solid concentration of 85-95%, and the evaporator does not crystallize.

[0020] Step 2: The concentrated material enters the crystallization tank for cooling and crystallization.

[0021] Step 3: The crystallized material enters a centrifuge for centrifugal treatment to separate the centrifuge mother liquor and centrifuge massecuite.

[0022] Step 4: Transfer the centrifuged sugar paste to a dissolving tank, add water and stir to dissolve into a sugar solution with a refractive index of 60% for later use.

[0023] Step 5: The centrifuged mother liquor is subjected to decolorization and separation treatment in sequence.

[0024] In the sixth step, the materials after centrifugation are subjected to chromatographic separation to obtain raffinate and extract respectively.

[0025] In the seventh step, the extract and the sugar solution from step four are added to a blending tank for blending to obtain a blending solution with a xylose content of 70-75%. The blending solution is then refined and processed into finished xylose.

[0026] The method for extracting finished xylose from xylose mother liquor of the present invention is further illustrated below by means of specific examples. Example 1

[0027] The first embodiment of the method for extracting finished xylose from xylose mother liquor of the present invention comprises the following steps:

[0028] Step 11: The xylose mother liquor is the centrifuged liquid from the xylose extraction process of the corncob hydrolyzate. The xylose mother liquor is placed in an evaporator and evaporated and concentrated to a solids concentration of 85-95%, and the evaporator does not crystallize. The xylose mother liquor has a dry matter concentration of 65% and a xylose content of 45%.

[0029] Step 12: The concentrated material enters a crystallization tank for cooling crystallization treatment with a cooling gradient of 1°C / h until the temperature drops to 25-30°C.

[0030] Step 13: The crystallized material enters a centrifuge for centrifugation with a centrifugal cycle of 600s to 900s, a rotation speed of 1200rpm, and a washing time of 10s to separate the centrifuged mother liquor and the centrifuged massecuite. The centrifuged mother liquor has a refractive index of 60% and a xylose content of 30%; the centrifuged massecuite has a moisture content of 1% and a xylose content of 80-85%.

[0031] Step 14: The centrifuged massecuite is transported to a dissolving tank through an auger for dissolution. Purified water is added during the dissolution process and stirred at 70°C to form a sugar solution with a refractive index of 60% for later use.

[0032] Step 15: The mother liquor is centrifuged and enters the decolorization process. 1% (w / w) activated carbon is added for decolorization treatment. The reaction temperature is 70°C. The refractive index of the decolorized material is controlled to be 50% and the transmittance is greater than 30%. The decolorized material is then subjected to ion exchange treatment. The conductivity of the material after ion exchange treatment is controlled to be less than 50 μs / cm and the pH is greater than 3.5.

[0033] Step 16: The cross-linked material is subjected to chromatographic separation in a chromatographic column to obtain a raffinate and an extract, respectively. The raffinate has a refractive index of 17.2% and a xylose content of 9.5%; the extract has a refractive index of 18% and a xylose content of 60-65%. The raffinate is concentrated and processed into a by-product for sale.

[0034] Step 17: Add the extract and the sugar solution after the massecuite is dissolved into a blending tank for blending to obtain a xylose content of 70-75% after blending. The blended liquid is then refined and processed into finished xylose. The refining process adopts conventional technology.

[0035] The xylose content obtained by the above method is greater than 99%, the xylose content in the effluent mother liquor is about 10%, and the xylose recovery rate can reach more than 80%.

[0036] This invention utilizes conventional centrifugation to preliminarily treat the xylose mother liquor, producing a high-purity centrifuged massecuite. This massecuite is then blended with the extract to achieve the required purity (70-75%) for the final xylose crystallization product. Compared to existing processes, this invention only requires chromatographic resin to increase the extract purity to 60-65%, effectively reducing the separation difficulty and requirements for the resin, thereby lowering the investment cost. Furthermore, due to the reduced chromatographic separation difficulty, the effluent mother liquor content can be stably controlled at around 10%, resulting in a more stable process. Furthermore, by combining this with conventional centrifugation, the chromatographic processing capacity is reduced to only 50% of that of conventional processes, facilitating cost management for enterprises.

[0037] 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 in the scope of protection of the present invention.

Claims

1. A method for extracting finished xylose from xylose mother liquor, characterized in that: The steps include: Step 1: The xylose mother liquor is the centrifugal liquid obtained during the xylose extraction process of the corncob hydrolyzate. The xylose mother liquor is placed in an evaporator and evaporated and concentrated to a solid concentration of 85-95%, and the evaporator does not crystallize. Step 2: The concentrated material enters the crystallization tank for cooling and crystallization; Step 3: The crystallized material enters a centrifuge for centrifugation to separate the centrifuged mother liquor and the centrifuged massecuite; Step 4: Transfer the centrifuged massecuite to a dissolving tank, add water and stir to dissolve into a sugar solution with a refractive index of 60% for later use; Step 5: The centrifuged mother liquor is subjected to decolorization and decolorization treatment in sequence; In the sixth step, the materials after the centrifugation are subjected to chromatographic separation to obtain a raffinate and an extract respectively; In the seventh step, the extract and the sugar solution from step four are added to a blending tank for blending to obtain a blending solution with a xylose content of 70-75%, which is then refined and processed into finished xylose. In step 2, during the cooling crystallization treatment, the temperature is lowered at a gradient of 1°C / h until the temperature drops to 25-30°C; In step 3, the centrifugation conditions are: a centrifugation period of 600s to 900s, a rotation speed of 1200 rpm, and a washing time of 10s; the resulting centrifuged mother liquor has a refractive index of 60% and a xylose content of 30%; the resulting centrifuged massecuite has a moisture content of 1% and a xylose content of 80-85%; In step 5, the decolorization treatment method is: adding 1% w / w activated carbon, the reaction temperature is 70°C, and the refractive index of the decolorized material is controlled to be 50% and the transmittance is greater than 30%; the ion exchange treatment method is: controlling the conductivity of the material after ion exchange treatment to be less than 50μs / cm and the pH to be greater than 3.5; In step 6, the refractive index of the raffinate is 17.2%, and the xylose content is 9.5%; the refractive index of the extract is 18%, and the xylose content is 60-65%.

2. The method for extracting finished xylose from xylose mother liquor according to claim 1, wherein In step 4, the dissolution treatment conditions are: adding purified water and stirring at a temperature of 70°C.

Images