A double-cycle furfural production system and process

Abstract

The invention discloses a double-circulation furfural production system, and technology. The technology comprises following steps: 1, corn cob and low concentration acetic acid are subjected to hydrolysis reaction so as to obtain a mixed solution of xylose and acetic acid, wherein the concentration of the low concentration acetic acid is controlled to be 1 to 2%, v / v; 2, acetic acid, sodium chloride, and o-nitroanisole are added into the mixed solution of xylose and acetic acid obtained in step 1, wherein the acetic acid concentration is controlled to be 3 to 6%, v / v, the sodium chloride concentration is controlled to be 5 to 10% by mass, the volume ratio of o-nitroanisole to the mixed solution is controlled to be 1:0.8-1.2, and in the reaction process, the reaction system is stirred continuously; 3, after reaction, the obtained reaction system is allowed to stand for a preset time period for layering, an upper layer water phase is recycled back into the step 1 to provide an acidic environment for corn cob hydrolysis, and a lower layer extracted phase is conveyed into a distillation column for separation of crude furfural and o-nitroanisole; and 4, the o-nitroanisole obtained through separation is recycled back into the step 3.

Description

technical field [0001] The disclosure belongs to the technical field of furfural preparation, and in particular relates to a double-cycle furfural production system and process. Background technique [0002] The information disclosed in this Background section is only intended to increase the understanding of the general background of the disclosure, and is not necessarily to be taken as an acknowledgment or any form of suggestion that the information constitutes prior art that is already known to those skilled in the art. [0003] Furfural, also known as furan formaldehyde, is widely used in many production fields such as medicine, petrochemical industry, and food additives. However, furfural can only be produced by hydrolysis of agricultural and forestry products. Plant fibers mainly contain cellulose, hemicellulose and lignin. Among them, pentosan contained in hemicellulose is hydrolyzed to generate pentose, and then furfural is produced by dehydration of pentose . [0...

AI Technical Summary

Problems solved by technology

The inventors found that the yield of furfural using the one-step sulfuric acid process is low, only about 45%; a large amount of waste water and waste residues are produced, and 1 ton of furfural is produced to produce 24 tons of highly polluted waste water; the raw material utilization rate is low, and 1 ton of furfural is produced, 11 corncobs are consumed. tons; the waste residue is blackened, and the cellulose and lignin are severely damaged

[0005] In addition, furfural prepared by dehydration of pentose sugar will react with xylose intermediates in an acidic environment, or furfural will undergo cross-linking, resulting in a large number of by-products, resulting in a low yield of furfural

Although the extractant has been added in the system prepared by furfural in the prior art, the prepared furfural is removed from the reaction system in time to reduce the side reaction of furfural, but the extraction speed and extraction rate of furfural by using the existing extractant The degree is difficult to guarantee, and then it is difficult to ensure the effective improvement of furfural yield

Moreover, in order to avoid excessive damage to cellulose during the hydrolysis of hemicellulose, organic acids are often used instead of sulfuric acid to provide an acidic environment for the hydrolysis of hemicellulose. However, when furfural is prepared, an extractant is added to the reaction system. The extractant is generally an organic solvent. According to the principle of similar miscibility, most organic acids will also dissolve in the extractant. On the one hand, it is difficult to ensure the direct recycling of organic acids. On the other hand, in the subsequent furfural refining process, it is necessary to increase the separation steps of furfural and organic acids. , which increases the processing procedure, thereby increasing the production cost of furfural

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