Technology utilizing biomass raw materials to produce furfural

Abstract

The invention relates to a preparation method of furfural, and specifically relates to a method for comprehensively utilizing biomass raw materials to produce furfural. In the preparation method, a mixed organic acid composed of formic acid and acetic acid is used to cook biomass raw materials in the presence of a hydrogen peroxide catalyst so as to obtain hemicelluloses, then the hemicelluloses are subjected to a separating and extracting treatment and high-temperature high-pressure evaporation to produce furfural, and a by-product namely biocarbon is obtained at the same time. The energy consumption of the whole reaction is low, moreover, biocarbon can be produced at the same time, and thus the economic benefit and environmental benefit for entrepreneurs are improved.

Description

technical field [0001] The invention relates to a method for preparing furfural, in particular to a method for comprehensively utilizing biomass raw materials to prepare furfural and concurrently produce biochar. Background technique [0002] Furfural, also known as furan formaldehyde, consists of two double bonds and an aldehyde group on the furan ring. This unique chemical structure can make it undergo oxidation, hydrogenation, chlorination, nitration and condensation reactions, and then generate many chemical compounds. Products are widely used in many production fields such as pesticides, pharmaceuticals, petrochemicals, food additives, and casting. [0003] Furfural is produced from plant fibers rich in pentosans, such as corn cobs, corn stalks, straw, bagasse, cottonseed hulls, straw, etc. The principle is that pentosans in plant fibers are first hydrolyzed into pentoses, The pentose sugars are then dehydrated to furfural. [0004] At present, there are mainly one-st...

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Problems solved by technology

However, this patent also has the following disadvantages: 1. From the description in the manual, it can be seen that the process uses organic acid mixed with a catalyst represented by sulfuric acid for the first step of catalysis, and a catalyst needs to be added for catalysis during the reaction; 2. This process uses organic acid and a catalyst represented by sulfuric acid to cook biomass together. In the step of distilling the organic acid, the sulfuric acid as a catalyst still remains in the final pentose solution, which makes the treatment of the obtained pentose sugar difficult in subsequent steps. The sulfate ions need to be taken out, which increases the processing steps; 3. Although the same organic acid is used for extracting and washing cellulose in the whole process, and the collected pretreatment liquid and washing liquid are directly used for recycling to the first step In the reaction kettle, a large amount of lignin and pentose sugar solution dissolved therein have also accumulated in the entire mixed liquor. In view of the limitation of the saturation of organic acid extraction, the effectiveness of the mixed black liquor to extract lignin will be greatly reduced. Therefore, this step Although it is a cyclic reaction, it has little effect on the overall extraction efficiency; 4. In the collected pretreatment liquid and washing liquid, a large amount of pentose sugars generated by cooking hemicellulose are dissolved, and the pentose sugars circulate with the mixed liquid for many times During the process, it will continuously contact with organic acids to generate esters through esterification reaction. This patent is aimed at the comprehensive utilization of lignocellulosic biomass, so it does not care whether the whole process can obtain pentose sugars alone, but For the process for the purpose of separating pentose sugars, this process is not applicable; 5. The black liquor obtained by mixing needs to be circulated for more than 3 times and then evaporated to separate the organic acids, and the concentrated solution obtained is diluted to make the lignin Precipitation will cause a huge amount of black liquor and concentrated liquor to be processed at one time, which not only affects the treatment efficiency but also makes it difficult to achieve process continuity

However, since the process needs to convert water into water vapor, it requires a lot of energy consumption. Although the aldehyde gas in the latter stage reaction can provide energy for the previous stage reaction, the energy consumption of the whole process is still relatively large.

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