Method for preparing furfural through fungus and grass two-step method

Abstract

The invention provides a technique for preparing furfural from Juncao by a two-step method, which comprises the following steps: crushing Juncao, mixing with a water solution containing a catalyst, and hydrolyzing in a high-pressure reaction kettle to prepare xylose; after the reaction is finished, carrying out solid-liquid separation, and recycling xylose liquid to increase the concentration of xylose; adding an additive into the xylose liquid, mixing with an organic solvent, feeding into a two-phase continuous reactor, hydrolyzing to prepare furfural, separating two phases after the reaction is finished, and distilling an organic phase to recover the furfural and the organic solvent; the organic solvent and the water phase are recycled respectively; the hydrolyzed and recycled solid corn cob residues are used for preparing high-value chemicals, pulp and plates. Compared with the prior art, the furfural is prepared through a fungus and grass two-step method, the production of humin is effectively inhibited, the furfural yield is improved, the water phase (catalyst / assistant) and an organic solvent circulating system are green and environment-friendly, the recycled corn cob residues can be used for preparing high-value chemicals, pulp and the like, the emission of wastewater, waste gas and waste residues is greatly reduced, and the win-win situation of economic benefits and environmental benefits can be achieved.

Description

Technical Field

[0001] The present invention belongs to the field of furfural preparation, and specifically provides a technology for preparing furfural by a two-step method using Juncao. Background Art

[0002] Furfural is a renewable biomass-based platform compound. The chemicals directly or indirectly synthesized from furfural can reach more than a thousand kinds, and it has a wide range of downstream applications and plays an important role in industrial production. At present, the only method to obtain furfural industrially still uses corncobs as raw materials. In the traditional one-step process for producing furfural from corncobs, steam is used to separate furfural from the reaction system. After the steam condenses, the furfural concentration is very low. Separating furfural with steam in the reaction stage is the fundamental reason for high energy consumption and a large amount of wastewater. Moreover, the cellulose and lignin in corncobs are not fully utilized and form waste residues, which is not only a waste of resources but also seriously pollutes the environment if not properly treated. Chinese Patent CN112020168B discloses a method for catalytically preparing furfural from corncobs. Corncobs are mixed with water and an organic solvent, and then an inorganic salt is added and reacted at 130 - 170 °C, and then the organic phase is distilled to obtain furfural. Using organic phase extraction improves the furfural yield, and the organic phase and aqueous phase are recycled to reduce wastewater discharge. However, the treatment of waste residues using corncobs as raw materials still faces the problem of heavy pollution that has not been solved. Chinese Patent CN109651309A uses methanol to dissolve the hemicellulose in corncobs and then performs solid-liquid separation. The separated liquid is added with toluene and sulfuric acid for hydrolysis reaction. Toluene continuously extracts furfural, promotes the forward hydrolysis reaction, and avoids side reactions, greatly improving the furfural yield. However, methanol also dissolves some cellulose while dissolving hemicellulose, and methanol needs to be separated from the aqueous phase. Chinese Patent CN104230860 discloses a two-stage method for catalytically preparing furfural from corncobs. In the first stage, corncobs are ultrasonically hydrolyzed to obtain xylose solution, and in the second stage, the hydrolysis solution is catalyzed by a solid acid. After the reaction, the solution is distilled and concentrated, and furfural is extracted by dichloromethane. In this method, xylose dehydrates to produce furfural in a single-phase system, and the problem of by-product humin has not been solved. The solid acid has a high cost and must be activated for repeated reuse. China is a major furfural production country. Optimizing furfural production technology, reducing energy consumption, increasing the yield, and reducing pollution are of great significance. Juncao is a perennial herbaceous plant selected by Chinese scientists to solve the "conflict between fungi and forests". Currently, it is mostly used in the fields of cultivating edible fungi and edible feed, and there is a lack of effective technical ways to utilize Juncao to prepare chemicals. Therefore, the high-value utilization of Juncao can not only improve the economic benefits of the Juncao industry but also provide a large amount of resources for other industries, which has very important practical significance.

[0003] This application addresses the problems of low product yield, heavy pollution from waste residue combustion, and large wastewater discharge in traditional corn cob furfural production processes. It aims to provide a two-step process for producing furfural from Juncao (a type of medicinal herb). Using Juncao as raw material, the process first hydrolyzes it into xylose. The xylose solution and organic solvent are then introduced into a dual-connected microreactor. Furfural is extracted during the reaction, inhibiting humin production and improving furfural yield. The aqueous phase (catalyst / auxiliary agent) and organic solvent recycling system is environmentally friendly. The recovered xylose residue can be used to prepare high-value chemicals and pulps, significantly reducing wastewater, waste gas, and waste residue emissions, expanding the Juncao industrial chain, and achieving a win-win situation for both economic and environmental benefits. Summary of the Invention

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: including the following steps: (1) First, crush the Juncao grass into 8-80 mesh particles, mix it with a solution containing catalyst and place it in a high-pressure reactor, and hydrolyze it at 140℃-240℃ to produce xylose. After the reaction, perform solid-liquid separation, collect the xylose solution and mix it with Juncao grass to continue hydrolysis, and repeat the cycle until the xylose concentration no longer increases, and obtain the required xylose solution; (2) Add auxiliaries and catalysts to the xylose solution, and then pump it into a two-phase continuous reactor with organic solvent to hydrolyze it to produce furfural. After the reaction, separate the two phases, distill the organic phase to recover furfural and organic solvent, and recycle the aqueous phase (catalyst / auxiliary agent) and organic solvent respectively; (3) The recovered solid residue is Juncao grass cellulose, which can be used to prepare pulp, boards, and high-value chemicals.

[0005] The catalyst mentioned in step (1) is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, maleic acid, and citric acid. The concentration of the catalyst in the aqueous solution is 0.01 mol / L to 2.0 mol / L, preferably 0.05 mol / L to 1.5 mol / L, more preferably 0.1 mol / L to 1.0 mol / L. The reaction residence time for hydrolyzing xylose at 140℃-240℃ (preferably 150℃-200℃, more preferably 160℃-180℃) is 10-240 min, preferably 15-180 min, more preferably 30-60 min.

[0006] The solid-liquid mass ratio of the Juncao granules to the aqueous phase is 5wt%-50wt%, preferably 10wt%-40wt%, and more preferably 15wt%-30wt%.

[0007] The auxiliary agent is one or more of sodium chloride, potassium chloride, lithium chloride, and magnesium chloride. The concentration of the auxiliary agent in the xylose solution is 0.01 mol / L-5 mol / L, preferably 0.05 mol / L-3 mol / L, and more preferably 0.1 mol / L-2.0 mol / L.

[0008] The catalyst mentioned in step (2) is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, maleic acid, and citric acid. The concentration of the catalyst in the aqueous solution is 0.05 mol / L to 5.0 mol / L, preferably 0.1 mol / L to 3 mol / L, and more preferably 0.5 mol / L to 2.0 mol / L.

[0009] The organic solvent is one or more of benzene, toluene, methyl isobutyl ketone, and dichloromethane.

[0010] In step (2), the flow rate ratio of the organic solvent to the xylose solution pumped into the continuous microreactor is 0.5:1 to 10:1, preferably 0.5:1 to 8:1, more preferably 1:1 to 5:1, the residence time of the xylose solution in the reactor is 5-240 min, preferably 10-180 min, more preferably 15-120 min, and the reaction temperature is 130-220℃, preferably 150-200℃, more preferably 160-180℃.

[0011] The hemicellulose content of the aforementioned Juncao fiber is less than 2%, and the cellulose content is more than 50%, which can be used to prepare pulp, boards or high value-added chemicals.

[0012] Beneficial effects:

[0013] This invention produces furfural through a two-step process and a continuous two-body system, solving the problem of low furfural yield in the one-pot process. Furthermore, by using biomass fungi and grass as raw materials, it avoids the difficulties in reusing cellulose and lignin from corn cobs. The recovered solid residue can be used to prepare high-value-added chemicals, pulp, and boards, offering both cost and environmental advantages. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the process flow of the present invention. 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 (Standard)

[0017] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%. Place the mixture in a high-pressure reactor and hydrolyze it at 200℃ for 30 min to produce xylose. After the reaction, separate the solid and liquid to collect the xylose solution. Mix it with 10 grams of Juncao again and continue hydrolysis. Repeat the cycle 3 times (repeat: mix with Juncao again, continue hydrolysis, separate the solid and liquid to collect the xylose solution) until the xylose concentration no longer increases. Separate the solid and liquid to collect the xylose solution. (2) Prepare the xylose solution to contain 2.0 A solution of sodium chloride auxiliaries and 0.4 mol / L sulfuric acid was prepared and then pumped into a PTFE reaction tube placed in an oven at flow rates of 1 ml / min and 3.0 ml / min, respectively. The reaction was allowed to proceed for 15 min for hydrolysis to produce furfural. After the reaction was completed, the organic phase was separated and the furfural was obtained by distillation. The organic solvent was recovered and the aqueous phase (catalyst / auxiliary agent) and organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 85%, and the recovered solid residue contained 65% cellulose and 0.2% hemicellulose.

[0018] Example 2 (Acid Concentration Variation)

[0019] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.01 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%. Place the mixture in a high-pressure reactor and hydrolyze it at 200℃ for 30 min to produce xylose. After the reaction, separate the solid and liquid to collect the xylose solution. Mix it with 10 grams of Juncao again and continue hydrolysis. Repeat the cycle 3 times (repeat: mix with Juncao again, continue hydrolysis, separate the solid and liquid to collect the xylose solution) until the xylose concentration no longer increases. Separate the solid and liquid to collect the xylose solution. (2) Prepare the xylose solution to contain 2.0 A solution of sodium chloride auxiliaries and sulfuric acid of 0.4 mol / L was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. The reaction was allowed to proceed for 15 min for hydrolysis to produce furfural. After the reaction was completed, the organic phase was separated and the furfural was obtained by distillation. The organic solvent was recovered and the aqueous phase (catalyst / auxiliary agent) and organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 55%, the cellulose content of the recovered solid residue was 52%, and the hemicellulose content was 1.8%.

[0020] Example 3 (Acid Concentration Change)

[0021] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of phosphoric acid solution with a concentration of 2.0 mol / L at a solid-liquid ratio of 10 wt%. Place the mixture in a high-pressure reactor and hydrolyze it at 200℃ for 30 min to produce xylose. After the reaction, separate the solid and liquid and collect the xylose solution. Mix it with 10 grams of Juncao again and continue hydrolysis. Repeat the cycle 3 times (repeat: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) Prepare the xylose solution to contain 2.0 mol / L. A solution of sodium chloride auxiliaries and 0.4 mol / L sulfuric acid was prepared, and then methyl isobutyl ketone (MIBK) was simultaneously pumped into a PTFE reaction tube placed in an oven at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the mixture was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was first separated, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 83%, and the recovered solid residue contained 58% cellulose and 0.1% hemicellulose.

[0022] Example 4 (Low Solid-Liquid Ratio)

[0023] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 1.0 g of Juncao and 100 g of 0.1 mol / L phosphoric acid solution, mix them at a solid-liquid ratio of 10 wt%, place them in a high-pressure reactor, and hydrolyze at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 g of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) Prepare the xylose solution to contain 2.0 mol / L A solution of sodium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was separated first, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 86%, and the recovered solid residue contained 62% cellulose and 0.19% hemicellulose.

[0024] Example 5 (High Solid-Liquid Ratio)

[0025] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 50 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%. Place the mixture in a high-pressure reactor and hydrolyze it at 200℃ for 30 minutes to produce xylose. After the reaction, separate the solid and liquid and collect the xylose solution. Then mix it with 10 grams of Juncao and continue hydrolysis. Repeat the cycle 3 times (repeat: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) Prepare the xylose solution to contain 2.0 mol / L. A solution of sodium chloride auxiliaries and 0.4 mol / L sulfuric acid was prepared, and then methyl isobutyl ketone (MIBK) was simultaneously pumped into a PTFE reaction tube placed in an oven at flow rates of 1 ml / min and 3.0 ml / min, respectively. The reaction was carried out for 15 min to hydrolyze and produce furfural. After the reaction was completed, the organic phase was first separated, and the furfural was obtained by distillation to recover the organic solvent. The recovered aqueous phase (catalyst / auxiliary agent) and organic solvent were recycled and reused respectively. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 54%, the recovered solid residue had a cellulose content of 52%, and a hemicellulose content of 0.2%.

[0026] Example 6 (Variation of organic phase / aqueous phase)

[0027] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%, place it in a high-pressure reactor, and hydrolyze it at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) Prepare the xylose solution to contain 2.0 mol / L chlorine A solution of sodium hydroxide auxiliaries and 0.4 mol / L sulfuric acid was prepared, and then methyl isobutyl ketone (MIBK) was simultaneously pumped into a PTFE reaction tube placed in an oven at flow rates of 0.5 ml / min and 1.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was first separated, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 75%, and the recovered solid residue contained 65% cellulose and 0.2% hemicellulose.

[0028] Example 7 (Variable Organic / Aqueous Phase)

[0029] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%, place it in a high-pressure reactor, and hydrolyze it at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) Prepare the xylose solution to contain 2.0 mol / L chlorine A solution of sodium hydroxide auxiliaries and 0.4 mol / L sulfuric acid was prepared, and then methyl isobutyl ketone (MIBK) was simultaneously pumped into a PTFE reaction tube placed in an oven at flow rates of 0.2 ml / min and 1.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was first separated, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 84%, and the recovered solid residue contained 65% cellulose and 0.2% hemicellulose.

[0030] Example 8 (Converted Sulfuric Acid)

[0031] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L sulfuric acid solution at a solid-liquid ratio of 10 wt%, place it in a high-pressure reactor, and hydrolyze it at 180°C for 30 minutes to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) prepare the xylose solution to contain 2.0 mol / L A solution of sodium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was separated first, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 55%, the cellulose content of the recovered solid residue was 51%, and the hemicellulose content was 0.2%.

[0032] Example 9 (Converted Hydrochloric Acid)

[0033] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L hydrochloric acid solution at a solid-liquid ratio of 10 wt%, place it in a high-pressure reactor, and hydrolyze it at 180°C for 30 minutes to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) prepare the xylose solution to contain 2.0 mol / L A solution of sodium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was first separated and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 53%, the cellulose content of the recovered solid residue was 52%, and the hemicellulose content was 0.1%.

[0034] Example 10 (Modified Maleic Acid)

[0035] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and 100 grams of 0.1 mol / L maleic acid solution, mix them at a solid-liquid ratio of 10 wt%, place them in a high-pressure reactor, and hydrolyze at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) prepare the xylose solution to contain 2.0 mol / L A solution of sodium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was separated first, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 75%, and the recovered solid residue contained 62% cellulose and 1.4% hemicellulose.

[0036] Example 11 (Modified Oxalic Acid)

[0037] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L oxalic acid solution at a solid-liquid ratio of 10 wt%, and place it in a high-pressure reactor to hydrolyze at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) prepare the xylose solution to contain 2.0 mol / L A solution of sodium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was separated first, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 68%, and the recovered solid residue contained 60% cellulose and 1.6% hemicellulose.

[0038] Example 12 (Citrate Reconstituted)

[0039] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L citric acid solution at a solid-liquid ratio of 10 wt%, place it in a high-pressure reactor, and hydrolyze it at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) prepare the xylose solution to contain 2.0 mol / L A solution of sodium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was first separated and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 78%, and the recovered solid residue contained 61% cellulose and 1.4% hemicellulose.

[0040] Example 13 (Variable Organic Phase Toluene)

[0041] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%. Place the mixture in a high-pressure reactor and hydrolyze it at 200℃ for 30 minutes to produce xylose. After the reaction, separate the solid and liquid and collect the xylose solution. Mix it with 10 grams of Juncao again and continue hydrolysis. Repeat the cycle 3 times (repeat: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases. (2) Prepare the xylose solution to contain 2.0 A solution of sodium chloride auxiliaries and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with toluene at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the mixture was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was separated first, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 85%, and the recovered solid residue contained 63% cellulose and 0.5% hemicellulose.

[0042] Example 14 (Variable Organic Phase Benzene)

[0043] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%. Place the mixture in a high-pressure reactor and hydrolyze it at 200℃ for 30 minutes to produce xylose. After the reaction, separate the solid and liquid and collect the xylose solution. Mix it with 10 grams of Juncao again and continue hydrolysis. Repeat the cycle 3 times (repeat: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases. (2) Prepare the xylose solution to contain 2.0 A solution of sodium chloride auxiliaries and 0.4 mol / L sulfuric acid was prepared and then pumped into a PTFE reaction tube placed in an oven at flow rates of 1 ml / min and 3.0 ml / min, respectively. The reaction was allowed to proceed for 15 min for hydrolysis to produce furfural. After the reaction was completed, the organic phase was separated and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 70%, and the recovered solid residue contained 58% cellulose and 0.9% hemicellulose.

[0044] Example 15 (Variable Organic Phase Dichloromethane)

[0045] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%. Place the mixture in a high-pressure reactor and hydrolyze it at 200℃ for 30 min to produce xylose. After the reaction, separate the solid and liquid and collect the xylose solution. Mix it with 10 grams of Juncao again and continue hydrolysis. Repeat the cycle 3 times (repeat: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases. (2) Prepare the xylose solution to contain 2.0 mg / L of xylose. A solution of sodium chloride auxiliaries and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with dichloromethane at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was separated first, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 68%, and the recovered solid residue contained 59% cellulose and 0.8% hemicellulose.

[0046] Example 16 (Lower Additive Concentration)

[0047] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%, place it in a high-pressure reactor, and hydrolyze it at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) prepare the xylose solution to contain 0.01 mol / L A solution of sodium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was separated first, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 65%, the cellulose content of the recovered solid residue was 63%, and the hemicellulose content was 0.5%.

[0048] Example 17 (Variable Additive Concentration)

[0049] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%, and place it in a high-pressure reactor to hydrolyze at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) Prepare the xylose solution to contain 5.0 mol / L A solution of sodium chloride auxiliaries and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. The reaction was allowed to proceed for 15 min for hydrolysis to produce furfural. After the reaction was completed, the organic phase was first separated and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 88%, and the recovered solid residue contained 62% cellulose and 0.3% hemicellulose.

[0050] Example 18 (Variation of Additive Type: Potassium Chloride)

[0051] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%, place it in a high-pressure reactor, and hydrolyze it at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) prepare the xylose solution to contain 2.0 mol / L A solution of potassium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was separated first, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 89%, and the recovered solid residue contained 63% cellulose and 0.5% hemicellulose.

[0052] Example 19 (Variable Additive Type: Lithium Chloride)

[0053] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%, place it in a high-pressure reactor, and hydrolyze it at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) prepare the xylose solution to contain 2.0 mol / L A solution of lithium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared and then simultaneously pumped into a PTFE reaction tube placed in an oven with methyl isobutyl ketone (MIBK) at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was separated first, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 83%, and the recovered solid residue contained 63% cellulose and 0.5% hemicellulose.

[0054] Example 20 (Magnesium chloride with variable additive)

[0055] (1) First, crush the Juncao "Oasis No. 1" into 8-80 mesh, weigh 10 grams of Juncao and mix it with 100 grams of 0.1 mol / L phosphoric acid solution at a solid-liquid ratio of 10 wt%, place it in a high-pressure reactor, and hydrolyze it at 200℃ for 30 min to produce xylose; after the reaction, separate the solid and liquid and collect the xylose solution, then mix it with 10 grams of Juncao and continue hydrolysis, repeating the cycle 3 times (repeated: mix with Juncao again, continue hydrolysis, separate the solid and liquid and collect the xylose solution) until the xylose concentration no longer increases; (2) prepare the xylose solution to contain 2.0 mol / L A solution of magnesium chloride auxiliary agent and 0.4 mol / L sulfuric acid was prepared, and then methyl isobutyl ketone (MIBK) was simultaneously pumped into a PTFE reaction tube placed in an oven at flow rates of 1 ml / min and 3.0 ml / min, respectively. After 15 min, the solution was hydrolyzed to produce furfural. After the reaction was completed, the organic phase was first separated, and the furfural was obtained by distillation. The organic solvent was recovered, and the aqueous phase (catalyst / auxiliary agent) and the organic solvent were recycled. (3) The recovered solid residue was cellulose, which can be used to prepare pulp, boards, and high-value chemicals. The final furfural yield was calculated to be 78%, and the recovered solid residue contained 61% cellulose and 0.5% hemicellulose.

Claims

1. A two-step method for producing furfural using Juncao (a type of fungus), characterized in that, Includes the following steps: (1) First, crush the Juncao grass into 8-80 mesh particles, mix it with a solution containing catalyst and place it in a high-pressure reactor. Hydrolyze it at 140℃-240℃ to produce xylose. After the reaction, separate the solid and liquid components, collect the xylose solution and mix it with Juncao grass to continue hydrolysis. Repeat the cycle until the xylose concentration no longer increases and obtain the required xylose solution. (2) Add the auxiliary agent and catalyst to the xylose solution, and then pump it into a two-phase continuous reactor with organic solvent to hydrolyze it to produce furfural. After the reaction, separate the two phases, distill the organic phase to recover furfural and organic solvent, and recycle the aqueous phase (catalyst / auxiliary agent) and organic solvent respectively. (3) The recovered solid residue is Juncao grass cellulose, which can be used to prepare pulp, boards and high-value chemicals.

2. The method for producing furfural using a two-step process with fungi and grass according to claim 1, characterized in that, The catalyst mentioned in step (1) is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, maleic acid, and citric acid. The concentration of the catalyst in the aqueous solution is 0.01 mol / L to 2.0 mol / L, preferably 0.05 mol / L to 1.5 mol / L, more preferably 0.1 mol / L to 1.0 mol / L. The reaction residence time for hydrolyzing xylose at 140℃-240℃ (preferably 150℃-200℃, more preferably 160℃-180℃) is 10-240 min, preferably 15-180 min, more preferably 30-60 min.

3. The method for producing furfural using a two-step process with fungi and grass according to claim 1, characterized in that, The solid-liquid mass ratio of the Juncao granules to the aqueous phase is 5wt%-50wt%, preferably 10wt%-40wt%, and more preferably 15wt%-30wt%.

4. The method for producing furfural using a two-step process with fungi and grass according to claim 1, characterized in that, The auxiliary agent is one or more of sodium chloride, potassium chloride, lithium chloride, and magnesium chloride. The concentration of the auxiliary agent in the xylose solution is 0.01 mol / L-5 mol / L, preferably 0.05 mol / L-3 mol / L, and more preferably 0.1 mol / L-2.0 mol / L.

5. The method for producing furfural using a two-step process with fungi and grass according to claim 1, characterized in that, The catalyst mentioned in step (2) is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, maleic acid, and citric acid. The concentration of the catalyst in the aqueous solution is 0.05 mol / L to 5.0 mol / L, preferably 0.1 mol / L to 3 mol / L, and more preferably 0.5 mol / L to 2.0 mol / L.

6. The method for producing furfural using a two-step process with fungi and grass according to claim 1, characterized in that, The organic solvent is one or more of benzene, toluene, methyl isobutyl ketone, and dichloromethane.

7. The method for producing furfural using a two-step process with fungi and grass according to claim 1, characterized in that, In step (2), the flow rate ratio of the organic solvent to the xylose solution pumped into the continuous microreactor is 0.5:1 to 10:1, preferably 0.5:1 to 8:1, more preferably 1:1 to 5:1, the residence time of the xylose solution in the reactor is 5-240 min, preferably 10-180 min, more preferably 15-120 min, and the reaction temperature is 130-220℃, preferably 150-200℃, more preferably 160-180℃.

8. The method for producing furfural using a two-step process with fungi and grass according to claim 1, characterized in that, The hemicellulose content of the aforementioned Juncao fiber is less than 2%, and the cellulose content is more than 50%, which can be used to prepare pulp, boards or high value-added chemicals.

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