Co-production method for preparing oligosaccharide and solid briquette fuel through succinic acid pretreatment of biomass

Abstract

The succinic acid catalyst is adopted, two carboxyl functional groups exist in molecules at the same time, higher catalytic activity is achieved, the corncobs are subjected to hydrothermal catalytic pretreatment, high-quality raw materials for preparing briquette fuel are obtained, and meanwhile xylooligosaccharide by-products with high economic benefits can be obtained. Meanwhile, the succinic acid is used as a food functional additive, does not need to be separated, also has a certain preservative effect, can inhibit the growth and reproduction of microorganisms in the food, prolongs the shelf life of the food, and is beneficial to keeping the freshness and quality of the food. Compared with corncob hemicellulose before treatment, most of the residues obtained after treatment are degraded, the carbon proportion in the residual residues is higher, the energy density is higher, and the heat value is increased.

Description

Technical Field

[0001] The present invention relates to a method for producing biomass raw materials with higher energy density by pretreating biomass with organic acid. The method uses succinic acid as a catalyst and corn cobs as raw materials, performs stirring catalytic pretreatment and degradation reaction at high temperature, produces molded fuel raw materials with higher calorific value, and obtains oligoxylose at the same time. The method belongs to the field of biomass chemical industry. Background Art

[0002] Succinic acid, an organic acid approved as a food additive, is naturally present in a variety of fruits and vegetables, such as apples, citrus fruits, and pineapples, and its safety is widely recognized. Succinic acid also has a certain antiseptic effect, inhibiting the growth and reproduction of microorganisms in food, extending the shelf life of food, helping to maintain food freshness and quality, and reducing food spoilage during storage and transportation. Moderate consumption of foods containing succinic acid can promote metabolism and has certain nutritional value.

[0003] Corncobs, a byproduct of corn processing, are abundant resources with great potential for application. Most corncobs are burned or dumped, resulting in significant resource underutilization and waste. Corncobs are composed of 40%-45% cellulose, 25%-35% hemicellulose, 17%-20% lignin, and small amounts of ash and extractives. The high xylan content makes corncobs a high-quality raw material for the production of xylooligosaccharides, paving the way for their high-value utilization. Furthermore, preparing corncobs into pelletized fuel reduces transportation and storage costs. Summary of the Invention

[0004] The purpose of the present invention is to use succinic acid as an acidic catalyst, corn cobs as raw materials, and adopt a stirring pretreatment method in hot water to degrade hemicellulose into oligoxylose and a small amount of xylose, and the remaining residue is used as a molding fuel raw material, thereby increasing the carbon ratio and calorific value.

[0005] The present invention uses succinic acid as a catalyst and performs hydrothermal pretreatment at high temperature to treat the biomass raw material. Hemicellulose is further degraded into oligoxylose and xylose. Succinic acid can serve as a functional additive in the oligoxylose product without separation. At the same time, the loss of cellulose and lignin is minimal, effectively increasing the energy density of the pelletized raw material. The method is characterized by comprising the following process steps: 1) Corncob: Corncob powder with a 40-mesh sieve pass rate of 99%. Moisture content <5%. 2) Organic acid pretreatment of corn cob powder: Succinic acid solution and corn cob powder are mixed in a certain proportion, reacted at 150° C. for 40 minutes, and after the reaction is completed, filtered, vacuum concentrated, and dried to obtain xylo-oligosaccharides. 3) Dry the residue obtained by filtration. 4) Add deionized water according to the mass of the dried residue to prepare a raw material with a certain moisture content, and let it stand in a sealed bag for 24 hours to balance the moisture. 5) After preparing the raw materials, fill the sample into the compression hole. Before the experiment begins, heat the mold to the set temperature and maintain it for 2 minutes after reaching the set temperature. Then, start compressing the raw materials at 10mm / min. When the pressure reaches the specified value, maintain the pressure for 3 minutes, then end the compression and demold at 5mm / min.

[0006] The method for preparing pretreated biomass solid shaped fuel is characterized in that in step 2), the corn cob:deionized water = 1:10 (w / v) is stirred at 150° C. for 40 minutes.

[0007] The method for preparing pretreated biomass solid shaped fuel is characterized in that the concentration of the succinic acid aqueous solution in step 2) is 0.1 mol / L or 0.3 mol / L.

[0008] The method for preparing pretreated biomass solid shaped fuel is characterized in that the drying temperature in step 3) is 50° C. and the drying time is 4 hours.

[0009] The method for preparing pretreated biomass solid shaped fuel is characterized in that the moisture content in step 4) is 12%.

[0010] The method for preparing pretreated biomass solid molded fuel is characterized in that the pressure in step 5) is 70.8 MPa and the molding is carried out at 80-120°C.

[0011] The advantages of the method for preparing pretreated biomass solid briquette fuel provided by the present invention are as follows:

[0012] 1. The corncob used in this invention is a common agricultural and forestry waste. Most corncobs are burned or dumped, resulting in significant resource underutilization and waste. Corncobs are composed of 40%-45% cellulose, 25%-35% hemicellulose, and 17%-20% lignin. With a wide variety of sources and low cost, they are ideal for preparing pellet fuel.

[0013] 2. the catalyst used in the present invention is succinic acid, succinic acid is a kind of organic acid naturally occurring in animals and plants, is widely used in the fields such as chemical industry, food, medicine, is a kind of food additive that is allowed, in addition it also has certain antiseptic effect, can suppress the growth and reproduction of microorganisms in food, extend the shelf life of food, contribute to keep the freshness and quality of food, reduce the deterioration loss of food in storage and transportation process, eat the food containing succinic acid in moderation, can promote body metabolism, have certain nutritional value.Xylose is separated as by-product, and oligoxylose is a kind of common functional oligosaccharide, has significant prebiotic characteristic, oligoxylose can selectively promote the proliferation of beneficial bacteria (such as bifidobacterium and lactic acid bacteria) in intestinal tract, suppresses harmful bacteria growth, improves intestinal microecological balance.Strengthen intestinal barrier function, reduce intestinal inflammation.Oligosaccharide also can be used as prebiotic and added in yogurt, beverage, baked food, strengthens the health effect of product, is a kind of product with higher economic benefit.

[0014] 4. The present invention uses succinic acid aqueous solution as a catalyst to degrade hemicellulose into xylooligosaccharides, which can also be used as a functional additive in xylooligosaccharide products without separation.

[0015] 5. Compared to the corncob hemicellulose before treatment, the residue obtained after treatment with the present invention has been substantially degraded. The remaining residue has a higher carbon content, a greater energy density, a higher calorific value, and a higher lignin content, offering significant advantages for the production of briquette fuel. Furthermore, the residual succinic acid in the residue can enhance the mold and antibacterial properties of the briquette fuel.

[0016] 6. The present invention reacts at 150°C for 40 minutes. During the reaction process, the maximum degradation ratio of hemicellulose is achieved while the yield of oligoxylose is the highest. At the same time, the degree of degradation of lignin and cellulose is reduced as much as possible. The process is safe and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The process flow chart of the embodiment combination. DETAILED DESCRIPTION

[0018] The present invention will be further described below with reference to the following examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0019] Example 1 30g of corn cobs passed through a 40-mesh sieve were added to 300mL of deionized water and 3.543g of succinic acid (0.1mol / L). After stirring, the mixture was reacted at 150°C and 500rpm / min for 40min. After completion of the reaction, the mixture was cooled, filtered, and dried to obtain a high-energy-density biomass feedstock. The yield of xylo-oligosaccharides was 33.18%, the hemicellulose removal rate reached 58.73%, and the cellulose removal rate was 3.55%. The raw material was tested and found to have a low calorific value of 15.8MJ / kg.

[0020] Example 2 30g of corn cobs passed through a 40-mesh sieve were added to 300mL of deionized water and 10.629g of succinic acid (0.3mol / L). After stirring, the mixture was reacted at 150°C and 500rpm / min for 40min. After completion of the reaction, the mixture was cooled, filtered, and dried to obtain a high-energy-density biomass feedstock. The yield of xylo-oligosaccharides was 52.86%, the hemicellulose removal rate reached 75.02%, and the cellulose removal rate was 6.70%. The raw material was tested and found to have a low calorific value of 16.3MJ / kg.

[0021] Example 3 Take 30g of corn cobs passed through a 40-mesh sieve, add 300mL of deionized water and 10.629g of succinic acid (0.3mol / L), stir evenly, and react at 150℃ at 500rpm / min for 40min. After the reaction, cool, filter, and dry to obtain a high-energy-density biomass raw material. After the reaction, the yield of oligoxylose was 52.86%, the hemicellulose removal rate reached 75.02%, and the cellulose removal rate was 6.70%. After the raw materials were prepared, 1±0.1g of the sample was first filled into the compression hole. Before the experiment began, the mold was heated to 80℃ and maintained for 2min after reaching the set temperature. Then, the raw material was compressed at 10mm / min. When the force reached 2000N, the pressure was maintained for 3min. Then, the lifting platform was raised and demolded at 5mm / min. The density of the molded particles is 1077.82kg / m 3 , the energy density is 18.91GJ / m 3 .

[0022] Example 4 Take 30g of corn cobs passed through a 40-mesh sieve, add 300mL of deionized water and 10.629g of succinic acid (0.3mol / L), stir evenly, and react at 150℃ at 500rpm / min for 40min. After the reaction, cool, filter, and dry to obtain a high-energy-density biomass raw material. After the reaction, the yield of oligoxylose was 52.86%, the hemicellulose removal rate reached 75.02%, and the cellulose removal rate was 6.70%. After the raw materials were prepared, 1±0.1g of the sample was first filled into the compression hole. Before the experiment began, the mold was heated to 100℃ and maintained for 2min after reaching the set temperature. Then, the raw material was compressed at 10mm / min. When the force reached 2000N, the pressure was maintained for 3min. Then, the lifting platform was raised and demolded at 5mm / min. The density of the molded particles is 1174.19kg / m 3 , the energy density is 20.60GJ / m 3 .

[0023] Example 5 Take 30g of corn cobs passed through a 40-mesh sieve, add 300mL of deionized water and 10.629g of succinic acid, stir evenly, and react at 150°C at 500rpm / min for 40min. After the reaction, cool, filter, and dry to obtain a high-energy-density biomass raw material. After the reaction, the yield of oligoxylose was 52.86%, the hemicellulose removal rate reached 75.02%, and the cellulose removal rate was 6.70%. After the raw materials were prepared, 1±0.1g of the sample was first filled into the compression hole. Before the experiment began, the mold was heated to 120°C and maintained for 2min after reaching the set temperature. Then, the raw material was compressed at 10mm / min. When the pressure reached 2000N, the pressure was maintained for 3min, and then the lifting platform was raised. The demolding was carried out at 5mm / min. The density of the molded particles is 1188.01kg / m 3 , the energy density is 20.84GJ / m 3 .

[0024] Comparative Example 1 30g of corn cobs passed through a 40-mesh sieve were added to 300mL of deionized water, stirred evenly, and reacted at 150°C and 500rpm / min for 40 minutes. After completion of the reaction, the reaction was cooled, filtered, and dried to produce a high-energy-density biomass feedstock. The hemicellulose removal rate reached 20.45%, and the cellulose removal rate was 2.53%. The raw material was tested for its low calorific value (LCV) of 14.0MJ / kg.

[0025] Comparative Example 2 After drying the corn cob at 105℃ for 4 hours after passing through a 40-mesh sieve, take 3g of the sample and add 0.409ml of deionized water. Let it stand in a sealed bag for 24 hours. After the standing is completed, fill the compression hole with 1±0.1g of the sample. Before the experiment begins, heat the mold to 100℃ and keep it at the set temperature for 2 minutes. Then start compressing the raw material at 10mm / min. When the force reaches 2000N, keep the pressure for 3 minutes. Then raise the lifting platform and demold at 5mm / min. The density of the molded particles is 969.47kg / m 3 , the energy density is 15.2GJ / m 3 .

Claims

1. The present invention uses succinic acid aqueous solution as a catalyst, uses hot water to catalytically pretreat corn cobs, and stirs the pretreatment at high temperature to efficiently produce oligoxylose. Succinic acid can be used as a functional additive in the oligosaccharide product without separation. After the oligoxylose is produced, the proportion of biomass residue charcoal is increased, and the calorific value is increased, which can be used to produce biomass pellet fuel with higher calorific value. In addition, the residual succinic acid can improve the mildew and antibacterial properties of the pellet fuel. The pretreatment method for preparing biomass fuel corn cobs is characterized by: The process steps include: 1) Corncob: Corncob powder with a 40-mesh sieve pass rate of 99%. Moisture content <5%. 2) Organic acid pretreatment of corn cob powder: Succinic acid solution and corn cob powder are mixed in a certain proportion, reacted at 150° C. for 40 minutes, and after the reaction is completed, filtered, vacuum concentrated, and dried to obtain xylo-oligosaccharides. 3) Dry the residue obtained by filtration. 4) Add deionized water according to the mass of the dried residue to prepare a raw material with a certain moisture content, and let it stand in a sealed bag for 24 hours until the moisture content is balanced. 5) After preparing the raw materials, fill the sample into the compression hole. Before the experiment begins, heat the mold to the set temperature and maintain it for 2 minutes after reaching the set temperature. Then, start compressing the raw materials at 10mm / min. When the pressure reaches the specified value, maintain the pressure for 3 minutes, then end the compression and demold at 5mm / min.

2. The method according to claim 1, wherein The corn cob in step 2) is mixed with deionized water in a ratio of 1:10 (w / v) and stirred at 150° C. for 40 min.

3. The method according to claim 1, wherein The concentration of the succinic acid aqueous solution in step 2) is 0.1 mol / L and 0.3 mol / L.

4. The method according to claim 1, wherein The drying temperature in step 3) is 50° C. and the drying time is 4 h.

5. The method according to claim 1, wherein The moisture content in step 4) is 12%.

6. The method according to claim 1, wherein The pressure in step 5) is 70.8 MPa, and the molding temperature is 80-120°C.

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