Method for preparing high-value dehydrated sugar through rapid pyrolysis

Abstract

The invention belongs to the field of biomass energy utilization, and particularly relates to a method for preparing high-value dehydrated sugar through rapid pyrolysis. The method comprises the following steps: by taking waste of palm plant seeds such as bodhi roots and oil palm fruits as raw materials, carrying out modification treatment on the raw materials according to a sequence of ball milling, cold plasma discharge treatment and water washing; and then carrying out rapid pyrolysis at 350-450 DEG C under an anaerobic condition, and condensing pyrolysis steam to obtain a liquid product rich in high-value dehydrated sugar, namely levomannan. The raw material adopted by the invention is palm plant seed waste generated in the handicraft processing process, and has the advantages of wide source, high yield and low cost. The three methods of ball milling, cold plasma discharge treatment and water washing are all green, environment-friendly and easy-to-operate physical methods, and de-ashing, depolymerization and structural activation of the raw materials can be effectively realized, so that the reactivity of the raw materials is remarkably improved, and a levomannan product is promoted to be generated in the pyrolysis process.

Description

Technical Field

[0001] This invention belongs to the field of biomass energy utilization, specifically relating to a method for rapidly pyrolyzing and preparing high-value (high-unit-price) dehydrated sugars (LM). Background Technology

[0002] L-Mannan (LM, 1,6-dehydrated-β-D-mannanopyranoside) is an important dehydrated sugar product formed by the pyrolysis of mannan hemicellulose components in biomass. LM possesses a chiral structure and holds significant application potential in pharmaceuticals, chemicals, energy, and environmental fields. Common palm seeds, such as linden root and ivory nut, are often important raw materials for handicrafts, generating substantial processing waste annually. These palm seeds typically contain abundant mannan, and pyrolysis of these biomass raw materials holds great potential for LM production; however, conventional pyrolysis of these raw materials struggles to yield high-yield and high-purity LM.

[0003] Currently, no publicly available patents have been found for the preparation of LM via biomass pyrolysis. Only a few patents disclose methods for preparing L-glucan (LG, 1,6-dehydrated-β-D-glucopyranose) via biomass pyrolysis. LG is the C2 epimer of LM, derived from the pyrolysis of biomass cellulose components. Chinese invention patent 202110087702.8 discloses a method for preparing LG via rapid pyrolysis of pretreated biomass. This method removes lignin through alkaline pretreatment and combines it with Fenton pretreatment to disrupt the cellulose structure, forming porous short-chain cellulose. Under the synergistic effect of coupled alkaline pretreatment and Fenton oxidation, the LG yield obtained from rapid pyrolysis of rice straw reaches up to 201.9 mg / g, significantly better than untreated and single pretreatment methods. Chinese invention patent 202410024928.7 discloses a method for rapidly pyrolyzing cellulose from pretreated biomass to prepare lignin (LG). This method uses an organic solvent-Fenton system at ambient temperature and pressure to remove lignin from corn cobs and degrade hemicellulose, increasing the cellulose content in the raw material. The LG yield obtained through rapid pyrolysis reaches a maximum of 160.2 mg / g, significantly superior to untreated samples and aqueous solutions. Existing research mainly focuses on LG preparation, with typical routes relying heavily on chemical reagents such as acids, alkalis, strong oxidants, and organic solvents, resulting in problems such as large reagent consumption, complex processes, and environmental pollution. Current research reports that the liquid product obtained from the direct pyrolysis of ivory fruit contains LM (silver ether), but the yield and purity of LM are low, making LM preparation difficult. Therefore, there is an urgent need to develop an environmentally friendly and industrially viable rapid pyrolysis route to achieve high-purity enrichment of LM products and high-value utilization of palm waste resources. This is precisely the core problem that this invention aims to solve. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-value dehydrated sugar products based on rapid pyrolysis. This method can obtain liquid products rich in LM, thereby realizing the high-value utilization of palm seed waste.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a method for rapidly preparing high-value dehydrated sugars through pyrolysis, comprising the following steps:

[0007] Palm seed waste raw materials are crushed, and the crushed raw materials are modified in sequence by ball milling, cold plasma discharge treatment and water washing. The modified raw materials are rapidly pyrolyzed under anaerobic conditions at 350-450 °C, and the pyrolysis steam is condensed to obtain a liquid product rich in L-mannan.

[0008] The aforementioned palm seed waste refers to the waste generated during the processing of Bodhi root, oil palm fruit, ivory fruit, and Bodhi seed. This waste is crushed and sieved to obtain powder particles smaller than 60 mesh.

[0009] In some embodiments, the ball milling is carried out in a planetary ball mill, the ball milling beads are made of zirconium oxide, corundum or stainless steel, the diameter of the ball milling beads is 2 to 10 mm, the ball-to-material ratio is 5:1 to 10:1, the ball milling time is 0.5 to 8 h, and the ball mill speed is 100 to 300 r / min.

[0010] In some embodiments, the cold plasma discharge treatment involves exposing the raw material to cold plasma. Cold plasma refers to low-temperature plasma with a high electron temperature but an ambient temperature close to room temperature, which can be generated by dielectric barrier discharge. The cold plasma discharge atmosphere is air, the cold plasma discharge time is 1–10 min, the discharge gap is 5–10 mm, the discharge frequency is 10 kHz, and the discharge voltage is 60–120 kV.

[0011] In some embodiments, the washing is carried out by soaking in deionized water with continuous stirring at room temperature, with a water-to-raw material mass ratio of not less than 50:1 and a washing time of 1 to 3 hours; then drying is performed in a vacuum drying oven at 60 ℃ for 24 hours.

[0012] In some embodiments, the heating rate of the rapid pyrolysis process is 100–1000 °C / s; the rapid pyrolysis time is 30 s–10 min.

[0013] In some embodiments, the condensation process employs multi-stage condensation to ensure high-purity enrichment of L-mannan in the liquid product.

[0014] The beneficial effects of this invention are as follows:

[0015] This invention provides a rapid pyrolysis method for palm seed waste, which can efficiently produce LM (laminated plasma). Taking bodhi root as an example, as a common and widely distributed palm seed waste, it is widely used in handicrafts, Buddhist cultural products, and other fields. However, the processing also generates a large amount of scrap and powdery waste. This type of waste is abundant, inexpensive to obtain, and has good reuse potential. This invention addresses this type of waste by using ball milling, cold plasma discharge, and water washing in sequence for modification treatment. The entire process is green and environmentally friendly, avoiding the potential pollution risks caused by traditional acid and alkali pretreatment, and has good industrial application prospects.

[0016] The innovation of this invention lies in its in-depth study of the biomass pyrolysis mechanism. Traditional research has largely focused on pyrolysis behavior under chemical conditions such as acids, alkalis, or organic solvents, and the products of direct pyrolysis of palm seed waste. This invention, however, employs purely physical methods for modification and systematically studies the effects of different treatment methods on the distribution of pyrolysis products, particularly on LM yield and purity. The results show that ball milling effectively reduces the particle size and crystallinity of the raw material, significantly promoting the pyrolysis reaction; cold plasma discharge treatment increases the number of oxygen-containing functional groups on the surface of the raw material, thereby enhancing its reactivity; and water washing removes ash from the raw material, reducing side reactions during pyrolysis. The combination of these three methods not only combines environmental friendliness and process simplicity but also significantly improves the purity of the pyrolysis products, providing a new technical pathway for the high-value utilization of palm seed waste.

[0017] Furthermore, the ball milling, cold plasma discharge, and water washing methods employed in this invention are all conventional, feasible, and easy-to-operate methods, and exhibit significant synergistic effects when used in combination. The raw materials modified by this invention can achieve high-purity enrichment of the target product LM during pyrolysis, while avoiding the generation of secondary pollutants such as acidic and alkaline waste liquids. The overall process is green, efficient, and environmentally friendly, possessing broad potential for industrialization. Detailed Implementation

[0018] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0019] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0020] The product yield calculation method in the following examples is as follows:

[0021] Product purity = peak area of ​​the product's chromatogram ÷ total peak area of ​​all organic products' chromatograms;

[0022] Product yield = Product mass ÷ Biomass feed mass

[0023] In the following examples, the content of LM was analyzed by gas chromatography / mass spectrometry, and quantification was performed using the external standard method. The LM yield was calculated as follows:

[0024] Purity of LM = Peak area of ​​LM chromatogram ÷ Total peak area of ​​all organic products chromatograms;

[0025] LM yield = mass of LM ÷ mass of biomass feedstock.

[0026] Unless otherwise specified, all percentages of yield in the following examples are by mass.

[0027] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0028] Example 1

[0029] This embodiment uses bodhi root as raw material and performs modification treatment in the sequence of ball milling, cold plasma discharge, and water washing. 4 g of dried bodhi root was ball-milled using zirconia beads for 4 h at a ball-to-material ratio of 10:1 at a mill speed of 200 r / min. The milled material was then subjected to cold plasma discharge treatment in air using dielectric barrier discharge (DPD) with a discharge gap of 6 mm, a treatment time of 5 min, a discharge frequency of 10 kHz, and a working voltage of 100 kV. Finally, water washing was performed at a water-to-raw material mass ratio of 50:1, with stirring at room temperature for 3 h. After treatment, the material was dried at 60℃ for 24 h. The treated material was then subjected to rapid pyrolysis, and the products were analyzed using gas chromatography-mass spectrometry (GC-MS) for online detection. The pyrolysis process was carried out at 400℃ with a heating rate of 100℃ / s under a helium atmosphere for 30 s. Gas chromatography quantitative analysis showed that the purity of LM was 64.59% and the yield of LM was 50.08 wt%.

[0030] Example 2

[0031] In this embodiment, oil palm fruit was used as raw material. The modification treatment was carried out sequentially under the same ball milling, cold plasma discharge, and water washing conditions as in Example 1. The treated raw material was then subjected to rapid pyrolysis under the same conditions as in Example 1. Gas chromatography quantitative analysis showed that the purity of LM was 61.55%, and the yield of LM was 44.85 wt%.

[0032] Example 3

[0033] In this embodiment, Bodhi seed was used as raw material. Modification was carried out sequentially under the same ball milling, cold plasma discharge, and water washing conditions as in Example 1. The treated raw material was then subjected to rapid pyrolysis under the same conditions as in Example 1. Gas chromatography quantitative analysis showed that the purity of LM was 61.78%, and the yield of LM was 45.80 wt%.

[0034] Example 4

[0035] In this embodiment, ivory nuts were used as raw material. Modification was carried out sequentially under the same ball milling, cold plasma discharge, and water washing conditions as in Example 1. The treated raw material was then subjected to rapid pyrolysis under the same conditions as in Example 1. Gas chromatography quantitative analysis showed that the purity of LM was 73.43%, and the yield of LM was 41.50 wt%.

[0036] Comparative Example 1

[0037] This comparative example uses linden root as raw material, and the raw material is subjected to rapid pyrolysis. The pyrolysis process is carried out at 400 °C with a heating rate of 100 °C / s, and the reaction time is 30 s under a helium atmosphere. Quantitative analysis by gas chromatography showed that the purity of LM was 37.41%, and the yield of LM was 7.28 wt%.

[0038] Comparative Example 2

[0039] This comparative example used linden root as raw material. The raw material was washed with water at a mass ratio of 50:1 and stirred at room temperature for 3 h. After washing, the sample was dried at 60 ℃ for 24 h, and the dried sample was used for subsequent pyrolysis experiments. The sample was subjected to rapid pyrolysis at 400 ℃ with a heating rate of 100 ℃ / s under a helium atmosphere for 30 s. The product was analyzed using gas chromatography-mass spectrometry (GC-MS) with online detection. Quantitative analysis by GC showed that the purity of LM was 50.77%, and the yield of LM was 17.43 wt%.

[0040] Comparative Example 3

[0041] This comparative example uses ivory nut as raw material. The raw material was subjected to cold plasma discharge treatment using dielectric barrier discharge in air atmosphere, with a discharge gap of 6 mm, a treatment time of 5 min, a discharge frequency of 10 kHz, and an operating voltage of 100 kV. The resulting sample was then subjected to rapid pyrolysis at 400 ℃ with a heating rate of 100 ℃ / s, reacting for 30 s under a helium atmosphere. Gas chromatography-mass spectrometry (GC-MS) was used for online detection of the pyrolysis products. Quantitative analysis by GC showed that the purity of LM was 52.53%, and the yield of LM was 17.20 wt%.

[0042] Comparative Example 4

[0043] This comparative example uses ivory nut as raw material. The raw material was ball-milled using zirconium oxide beads for 4 hours at a ball-to-material ratio of 10:1 at a mill speed of 200 r / min. After modification, the resulting sample underwent rapid pyrolysis, and the pyrolysis products were analyzed using gas chromatography-mass spectrometry (GC-MS) with online detection. The pyrolysis process was carried out at 400 °C with a heating rate of 100 °C / s under a helium atmosphere for 30 s. Quantitative analysis by GC showed that the purity of LM was 28.61%, and the yield was 10.67 wt%.

[0044] Comparative Example 5

[0045] This comparative example uses ivory nut as raw material, which undergoes sequential water washing and cold plasma discharge treatment. The water washing and cold plasma discharge treatment conditions and steps are the same as in Example 1. The obtained sample is subjected to rapid pyrolysis, and the product is analyzed using gas chromatography-mass spectrometry (GC-MS) online detection technology. The pyrolysis process is carried out at 400 °C with a heating rate of 100 °C / s, and the reaction time is 30 s under a helium atmosphere. Quantitative analysis by gas chromatography shows that the purity of LM is 64.42%, and the yield of LM is 24.53 wt%.

[0046] Comparative Example 6

[0047] This comparative example uses ivory nut as raw material, which undergoes sequential washing and ball milling. The washing and ball milling conditions and steps are the same as in Example 1. The samples after these two pretreatment steps are subjected to rapid pyrolysis, and the products are analyzed using gas chromatography-mass spectrometry (GC-MS) with online detection. The pyrolysis process is carried out at 400 °C with a heating rate of 100 °C / s, under a helium atmosphere for 30 s. Quantitative analysis by gas chromatography shows that the purity of LM is 50.15%, and the yield of LM is 23.00 wt%.

[0048] Comparative Example 7

[0049] The raw material for this comparative example was ivory fruit, which underwent modification treatment in the order of ball milling, water washing, and cold plasma discharge. The specific treatment conditions for each step were the same as in Example 1. After modification, the sample was subjected to rapid pyrolysis, and the product was analyzed using gas chromatography-mass spectrometry (GC-MS) online detection technology. The pyrolysis process was carried out at 400 °C with a heating rate of 100 °C / s, and the reaction was carried out for 30 s under a helium atmosphere. Quantitative analysis by gas chromatography showed that the purity of LM was 71.31%, and the yield of LM was 31.34 wt%.

[0050] Comparative Example 8

[0051] The raw material for this comparative example was ivory fruit, which underwent modification treatment in the order of water washing, cold plasma discharge, and ball milling. The specific treatment conditions for each step were the same as in Example 1. After modification, the sample was subjected to rapid pyrolysis, and the product was analyzed using gas chromatography-mass spectrometry (GC-MS) for online detection. The pyrolysis process was carried out at 400 °C with a heating rate of 100 °C / s, and the reaction was carried out for 30 s under a helium atmosphere. Quantitative analysis by gas chromatography showed that the purity of LM was 67.71%, and the yield of LM was 32.49 wt%.

[0052] Comparative Example 9

[0053] The raw material for this comparative example was ivory fruit, which underwent modification treatment in the order of water washing, ball milling, and cold plasma discharge. The specific treatment conditions for each step were the same as in Example 1. The treated sample was subjected to rapid pyrolysis, and the product was analyzed using gas chromatography-mass spectrometry (GC-MS) for online detection. The pyrolysis process was carried out at 400 °C with a heating rate of 100 °C / s, and the reaction was carried out for 30 s under a helium atmosphere. Quantitative analysis by gas chromatography showed that the purity of LM was 72.45%, and the yield of LM was 33.16 wt%.

[0054] Comparative Example 10

[0055] The raw material for this comparative example was ivory fruit, which underwent modification treatment in the sequence of cold plasma discharge, water washing, and ball milling. The specific treatment conditions for each step were the same as in Example 1. The treated sample was subjected to rapid pyrolysis, and the product was analyzed using gas chromatography-mass spectrometry (GC-MS) for online detection. The pyrolysis process was carried out at 400 °C with a heating rate of 100 °C / s, and the reaction was carried out for 30 s under a helium atmosphere. Quantitative analysis by gas chromatography showed that the purity of LM was 62.67%, and the yield of LM was 22.14 wt%.

[0056] Comparative Example 11

[0057] The raw material for this comparative example was ivory fruit, which underwent modification treatment in the order of cold plasma discharge, ball milling, and water washing. The specific treatment conditions for each step were the same as in Example 1. The treated sample was subjected to rapid pyrolysis, and the product was analyzed using gas chromatography-mass spectrometry (GC-MS) for online detection. The pyrolysis process was carried out at 400 °C with a heating rate of 100 °C / s, and the reaction was carried out for 30 s under a helium atmosphere. Quantitative analysis by gas chromatography showed that the purity of LM was 66.57%, and the yield of LM was 25.25 wt%.

[0058] The pyrolysis raw materials in the above embodiments include biomass raw materials such as oil palm fruit, bodhi root, star moon bodhi, and ivory fruit. The content of mannan in the biomass raw materials is different, so the LM yield is different, but it does not affect the description of the embodiments of the present invention.

[0059] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. A method for the fast pyrolysis production of high value anhydrosugars, characterized in that, The method comprises the following steps: The palm plant seed waste material is crushed, and the crushed material is modified by ball milling, cold plasma discharge treatment and water washing in sequence; the modified material is rapidly pyrolyzed under anaerobic conditions at 350-450 DEG C, and the pyrolysis vapor is condensed to obtain a liquid product rich in levomannan.

2. The production method according to claim 1, characterized by, The palm plant seed waste is waste generated in the processing of Bodhi roots, oil palm fruits, ivory fruits or star moon Bodhi; the particle size of the crushed powder is less than 60 mesh.

3. The production method according to claim 1, characterized by, The ball milling is performed in a planetary ball mill, the ball milling bead material is zirconia, corundum or stainless steel, the ball milling bead diameter is 2-10 mm, the ball milling bead to material ratio is 5:1-10:1, the ball milling time is 0.5-8 h, and the ball mill rotation speed is 100-300 r / min.

4. The preparation method according to claim 1, characterized in that, The cold plasma discharge treatment is performed in an air atmosphere, the cold plasma discharge time is 1-10 min, the discharge gap is 5-10 mm, the discharge frequency is 10 kHz, and the discharge voltage is 60-120 kV.

5. The preparation method according to claim 1, characterized in that, The water washing is performed by immersing the material in deionized water and continuously stirring, at room temperature, the water to material mass ratio is not less than 50:1, and the water washing time is 1-3 h.

6. The method of claim 1, wherein, The rapid pyrolysis process has a temperature rising rate of 100-1000 DEG C / s; and the rapid pyrolysis time is 30 s-10 min.

7. The preparation method according to claim 1, characterized in that, The condensation process adopts multi-stage condensation.