Method for preparing furfural from Juncao

Abstract

The invention provides a production method for preparing furfural from Juncao, which comprises the following specific steps: cutting Juncao, mixing the cut Juncao with a sulfuric acid solution, introducing high-pressure steam for hydrolysis, condensing outlet steam, collecting crude aldehyde, and purifying the crude aldehyde through a rectifying tower in a refining workshop to obtain qualified furfural; and the recovered solid residue is Juncao cellulose and can be used for preparing high-value chemicals, pulp and plates. Compared with an existing corncob furfural technology, the yield of furfural prepared from the fungus grass is larger than 50%, the discharge amount of solid residues is greatly reduced, cellulose can still be utilized in a high-value mode after fungus grass hemicellulose is converted into furfural, the comprehensive additional value of the fungus grass is greatly improved, and the method has the cost advantage and the environment-friendly advantage and can be used for mass production of enterprises.

Description

Technical Field

[0001] This invention relates to a method for preparing furfural, specifically a method for producing furfural using Juncao grass. Background Technology

[0002] Furfural is an important platform chemical widely used in organic chemicals and energy fields. To date, the industrial production of furfural typically uses corn cobs as raw material in a one-step process. However, the production of furfural from corn cobs involves numerous side reactions such as condensation and esterification, producing large amounts of colloids that adhere to the surface of unreacted cellulose and lignin. This makes the cellulose and lignin in the post-reaction waste difficult to reuse, generally only used as fuel in production. It is estimated that for every ton of furfural produced, 10-12 tons of waste residue are removed in the hydrolysis stage, consuming approximately 20 tons of water. China is a major furfural exporter, accounting for over 70% of global furfural production. Therefore, optimizing furfural industrial production technology, reducing energy consumption, increasing yield, and reducing pollution are of great significance to a major furfural producer. Juncao (a type of grass) is a perennial herbaceous plant selected by Chinese scientists to solve the "fungus-forest conflict." It has high photosynthetic efficiency, large biomass, well-developed root system, and high yield; it also exhibits strong biological resistance, being cold-resistant, drought-resistant, flood-resistant, salt-alkali-resistant, and rapidly establishing forests, with a yield of up to 25 tons per mu (approximately 0.16 acres). Juncao (a type of grass) has a high hemicellulose content and is easy to extract, making it a promising biomass resource. This application addresses the problems of large emissions of furfural waste from corn cob production and heavy pollution from waste incineration by providing a method for producing furfural using Juncao. The furfural yield from Juncao is greater than 50%, and the solid residue emissions are significantly reduced. After the hemicellulose of Juncao is converted into furfural, the cellulose can be used to prepare pulp and boards, increasing the overall added value of Juncao, expanding the Juncao industrial chain, and offering both cost and environmental advantages. Summary of the Invention

[0003] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0004] A method for producing furfural from Juncao grass is characterized by the following steps: First, Juncao grass is cut into 2-5 cm segments and then mixed with an aqueous solution containing a catalyst. The uniformly mixed Juncao grass is placed in a hydrolysis reactor, and a steam generator is turned on to continuously introduce high-pressure steam into the hydrolysis reactor. After the required temperature and pressure for the reaction are reached, the outlet valve is opened to release the steam. When the reaction is complete, the steam supply is stopped, and the outlet valve of the steam generator is closed. The time from when the steam generator is turned on to when it is turned off is recorded as the reaction time. As the hydrolysis reaction proceeds, furfural is carried out of the hydrolysis reactor by the steam. The furfural vapor is condensed by a condenser to obtain crude furfural, which is then purified by distillation to obtain the finished furfural product. The solid residue discharged from the hydrolysis reactor is Juncao grass cellulose.

[0005] The catalyst is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, maleic acid, and citric acid.

[0006] The concentration of the catalyst aqueous solution is 1wt%-10wt%, preferably 2wt%-6wt%, and more preferably 2.5wt%-4wt%.

[0007] The mass ratio of the catalyst acid to the fungus grass is 0.5%-10%, preferably 0.8%-8%, and more preferably 1.2%-5%.

[0008] The required temperature for the hydrolysis treatment is 150-220℃, preferably 160-200℃, more preferably 165-180℃, and the pressure in the hydrolysis reactor is 0.5-1.2MPa, preferably 0.6-1.0, more preferably 0.65-0.85. The fungus-straw mixture is reacted in the reactor for 2-8 hours, preferably 3-6 hours, more preferably 4-5 hours.

[0009] The hemicellulose content in the aforementioned Juncao fiber is less than 2%, and the cellulose content is 45%-70%.

[0010] The aforementioned Juncao cellulose can be used to prepare high-value chemicals, pulp, or boards.

[0011] Beneficial effects:

[0012] 1. This invention uses biomass fungi and grass as raw materials to prepare furfural, avoiding the problem of cellulose and lignin in the waste residue after the reaction of corn cobs as raw materials being difficult to reuse. The recovered solid residue can be used to prepare high-value-added chemicals, pulp, and boards, which has cost advantages and environmental advantages.

[0013] 2. This invention uses raw material biomass fungi grass to prepare furfural, which expands the raw materials for furfural production and extends the fungi grass industry chain, thus having economic and social benefits.

[0014] Compared with existing corn cob-to-furfural technology, the furfural yield of Juncao is greater than 50%, and the solid residue emissions are significantly reduced. After the hemicellulose of Juncao is converted into furfural, the cellulose can still be utilized at a high value, which greatly improves the comprehensive added value of Juncao. It has cost advantages and environmental advantages, and can be put into mass production by enterprises. Detailed Implementation

[0015] The present invention can be better understood from the following embodiments. However, the descriptions of the embodiments are for illustrative purposes only and should not, and will not, limit the invention as described in detail in the claims.

[0016] Example 1

[0017] First, the Juncao "Oasis No. 1" was cut into 2-5 cm segments. 1000 g of Juncao and 500 g of 3.0 wt% sulfuric acid solution were weighed and sprayed evenly. The evenly mixed Juncao was placed in a hydrolysis reactor. Then, the steam generator valve was opened to continuously introduce steam into the hydrolysis reactor. After the temperature and pressure inside the hydrolysis reactor reached 180℃ and 1.0 MPa, the outlet valve of the hydrolysis reactor was opened to continuously release steam carrying out furfural. The steam was continuously passed through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeded, the furfural was carried out of the hydrolysis reactor by the steam. The furfural steam was condensed by a condenser to obtain crude furfural. After purification by a distillation column in the refining workshop, the finished furfural product was obtained. The furfural yield was calculated to be 65%. The solid residue discharged from the hydrolysis reactor was Juncao cellulose, which contained 58% cellulose, 1.3% hemicellulose, and 37% lignin.

[0018] Example 2 (Changing the Acid Amount)

[0019] First, cut the Juncao "Oasis No. 1" into 2-5 cm pieces. Weigh 1000g of Juncao and spray it evenly with 167g of a 3.0wt% sulfuric acid solution. Place the evenly mixed Juncao into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. After the temperature and pressure inside the hydrolysis reactor reach 180℃ and 0.8MPa, open the outlet valve of the hydrolysis reactor to continuously release steam carrying out furfural. The steam continuously passes through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 50%. The solid residue discharged from the hydrolysis reactor is Juncao cellulose, which contains 48% cellulose, 1.5% hemicellulose, and 39% lignin.

[0020] Example 3 (Changing the Acid Amount)

[0021] First, cut the Juncao "Oasis No. 1" into 2-5 cm pieces. Weigh 1000g of Juncao and spray it evenly with 1000g of a 10.0wt% sulfuric acid solution. Place the evenly mixed Juncao into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. After the temperature and pressure inside the hydrolysis reactor reach 180℃ and 1.0MPa, open the outlet valve of the hydrolysis reactor to continuously release steam and carry out furfural. The steam continuously passes through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 52%. The solid residue discharged from the hydrolysis reactor is Juncao cellulose, which contains 68% cellulose, 0.2% hemicellulose, and 36% lignin.

[0022] Example 4 (Changing the temperature)

[0023] First, cut the Juncao "Oasis No. 1" into 2-5 cm pieces. Weigh 1000g of Juncao and spray it evenly with 1000g of a 10.0wt% sulfuric acid solution. Place the evenly mixed Juncao into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. After the temperature and pressure inside the hydrolysis reactor reach 150℃ and 0.6MPa, open the outlet valve of the hydrolysis reactor to continuously release steam carrying out furfural. The steam continuously passes through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 52%. The solid residue discharged from the hydrolysis reactor is Juncao cellulose, which contains 52% cellulose, 1.8% hemicellulose, and 31% lignin.

[0024] Example 5 (Changing the temperature)

[0025] First, cut the Juncao "Oasis No. 1" into 2-5 cm pieces. Weigh 1000g of Juncao and spray it evenly with 500g of a 3.0wt% sulfuric acid solution. Place the evenly mixed Juncao into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. When the temperature inside the hydrolysis reactor reaches 220℃ and 2.3MPa, open the outlet valve of the hydrolysis reactor to continuously release steam carrying out furfural. The steam continuously passes through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 58%. The solid residue discharged from the hydrolysis reactor is Juncao cellulose, which contains 57% cellulose, 1.3% hemicellulose, and 33% lignin.

[0026] Example 4 (Changing the hydrolysis time)

[0027] First, cut the Juncao "Oasis No. 1" into 2-5 cm pieces. Weigh 1000g of Juncao and spray it evenly with 500g of a 3.0wt% sulfuric acid solution. Place the evenly mixed Juncao into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. When the temperature and pressure inside the hydrolysis reactor reach 180℃ and 1.0MPa, open the outlet valve of the hydrolysis reactor to continuously release steam carrying out furfural. The steam continuously passes through the hydrolysis reactor for 2 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 55%. The solid residue discharged from the hydrolysis reactor is Juncao cellulose, which contains 54% cellulose, 1.9% hemicellulose, and 32% lignin.

[0028] Example 5 (Changing the hydrolysis time)

[0029] First, cut the Juncao "Oasis No. 1" into 2-5 cm pieces. Weigh 1000g of Juncao and spray it evenly with 500g of a 3.0wt% sulfuric acid solution. Place the evenly mixed Juncao into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. When the temperature and pressure inside the hydrolysis reactor reach 180℃ and 1.0MPa, open the outlet valve of the hydrolysis reactor to continuously release steam carrying out furfural. The steam continuously passes through the hydrolysis reactor for 8 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 70%. The solid residue discharged from the hydrolysis reactor is Juncao cellulose, which contains 59% cellulose, 0.1% hemicellulose, and 39% lignin.

[0030] Example 6 (Changing the type of acid)

[0031] First, cut the Juncao "Oasis No. 1" into 2-5 cm pieces. Weigh 1000g of Juncao and spray it evenly with 500g of a 3.0wt% hydrochloric acid solution. Place the evenly mixed Juncao into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. When the temperature inside the hydrolysis reactor reaches 180℃ and 1.0MPa, open the outlet valve of the hydrolysis reactor to continuously release steam, carrying out furfural. The steam continuously passes through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 66%. The solid residue discharged from the hydrolysis reactor is Juncao cellulose, which contains 59% cellulose, 0.8% hemicellulose, and 36% lignin.

[0032] Example 7 (Changing the type of acid)

[0033] First, cut the Juncao "Oasis No. 1" into 2-5 cm pieces. Weigh 1000g of Juncao and 500g of a 3.0wt% phosphoric acid solution and spray them evenly. Place the evenly mixed Juncao into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. When the temperature inside the hydrolysis reactor reaches 180℃ and 1.0MPa, open the outlet valve of the hydrolysis reactor to continuously release steam carrying out furfural. The steam continuously passes through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 58%. The solid residue discharged from the hydrolysis reactor is Juncao cellulose, which contains 48% cellulose, 1.9% hemicellulose, and 33% lignin.

[0034] Example 8 (Changing the type of acid)

[0035] First, cut the Juncao "Oasis No. 1" into 2-5 cm pieces. Weigh 1000g of Juncao and spray it evenly with 500g of a 3.0wt% oxalic acid solution. Place the evenly mixed Juncao into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. When the temperature and pressure inside the hydrolysis reactor reach 180℃ and 1.0MPa, open the outlet valve of the hydrolysis reactor to continuously release steam, carrying out furfural. The steam continuously passes through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 61%. The solid residue discharged from the hydrolysis reactor is Juncao cellulose, which contains 49% cellulose, 1.7% hemicellulose, and 34% lignin.

[0036] Example 9 (Changing the type of acid)

[0037] First, cut the "Oasis No. 1" Juncao grass into 2-5 cm pieces. Weigh 1000g of Juncao grass and spray it evenly with 500g of a 3.0wt% maleic acid solution. Place the evenly mixed Juncao grass into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. When the temperature and pressure inside the hydrolysis reactor reach 180℃ and 1.0MPa, open the outlet valve of the hydrolysis reactor to continuously release steam carrying out furfural. The steam continuously passes through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 63%. The solid residue discharged from the hydrolysis reactor is Juncao grass cellulose, which contains 56% cellulose, 1.2% hemicellulose, and 38% lignin.

[0038] Example 10 (Changing the type of acid)

[0039] First, cut the "Oasis No. 1" Juncao grass into 2-5 cm pieces. Weigh 1000g of Juncao grass and spray it evenly with 500g of a 3.0wt% citric acid solution. Place the evenly mixed Juncao grass into a hydrolysis reactor, then open the steam generator valve to continuously introduce steam into the hydrolysis reactor. When the temperature inside the hydrolysis reactor reaches 180℃ and 1.0MPa, open the outlet valve of the hydrolysis reactor to continuously release steam, carrying out furfural. The steam continuously passes through the hydrolysis reactor for 6 hours. As the hydrolysis reaction proceeds, the furfural is carried out of the hydrolysis reactor by the steam. The furfural steam is condensed by a condenser to obtain crude furfural, which is then purified by a distillation column in the refining workshop to obtain the finished furfural product. The furfural yield is calculated to be 67%. The solid residue discharged from the hydrolysis reactor is Juncao grass cellulose, which contains 58% cellulose, 0.9% hemicellulose, and 36% lignin.

[0040] Example 11 (Pulping with recycled Juncao cellulose)

[0041] The recovered Juncao cellulose is fed into a cooking reactor, and a cooking liquor composed of sodium hydroxide and sodium sulfide is added. The effective alkali dosage (based on sodium oxide and oven-dried Juncao cellulose) is 5%-10%, the sulfidation degree (based on sodium oxide) is 25%, and the solid-liquid ratio is 1:6 (g / ml). The mixture is cooked at 165℃ for 3 hours to obtain the initial Juncao pulp. Then, after pulping and bleaching, a dissolving pulp with a cellulose content of 90% is obtained.

Claims

1. A method for producing furfural from Juncao grass, characterized in that, First, cut the Juncao grass into 2-5 cm sections and mix it with an aqueous solution containing a catalyst. Place the well-mixed Juncao grass into a hydrolysis reactor and continuously introduce high-pressure steam into the reactor through a steam generator. Once the required temperature and pressure for the reaction are reached, open the outlet valve to release the steam. Stop introducing steam when the reaction is complete and close the outlet valve of the steam generator. The time from when the steam generator is open to when it is closed is recorded as the reaction time. As the hydrolysis reaction proceeds, furfural is carried out of the hydrolysis reactor by the steam. The furfural vapor is condensed by a condenser to obtain furfural, which is then purified by distillation to obtain the finished furfural product. The solid residue discharged from the hydrolysis reactor is Juncao grass cellulose.

2. The method according to claim 1, characterized in that, The catalyst is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, maleic acid, and citric acid.

3. The method according to claim 1 or 2, characterized in that, The concentration of the catalyst aqueous solution is 1wt%-10wt%, preferably 2wt%-6wt%, and more preferably 2.5wt%-4wt%.

4. The method according to claim 1, characterized in that, The mass ratio of catalyst acid to fungicide is 0.5%-10%, preferably 0.8%-8%, and more preferably 1.2%-5%.

5. The method according to claim 1, characterized in that, The required temperature for the hydrolysis treatment is 150-220℃, preferably 160-200℃, more preferably 165-180℃, and the pressure in the hydrolysis reactor is 0.5-1.2MPa, preferably 0.6-1.0, more preferably 0.65-0.

85. The fungus-straw mixture is reacted in the reactor for 2-8 hours, preferably 3-6 hours, more preferably 4-5 hours.

6. The method according to claim 1, characterized in that, The hemicellulose content in the aforementioned Juncao fiber is less than 2%, and the cellulose content is 45%-70%.

7. The method for producing furfural from Juncao grass according to claim 1, characterized in that, The aforementioned Juncao cellulose can be used to prepare high-value chemicals, pulp, or boards.