阅读说明：本技术 一种糠醛的制备工艺 (Preparation process of furfural ) 是由 冯维春 徐婷 王艳 王灏 梁辉 于 2019-09-09 设计创作，主要内容包括：本发明公开一种糠醛的制备工艺：通过使用新的催化剂代替传统的硫酸催化,并采用连续精制的方法制备糠醛。本发明解决了现有糠醛制备工艺中存在的产品收率低、生产过程中耗能高、废水废气污染严重等问题。提供了一种效率高、污染少、能耗低的糠醛制备工艺。(The invention discloses a preparation process of furfural, which comprises the following steps: the furfural is prepared by using a new catalyst to replace the traditional sulfuric acid catalyst and adopting a continuous refining method. The invention solves the problems of low product yield, high energy consumption in the production process, serious pollution of waste water and waste gas and the like in the existing furfural preparation process. Provides a furfural preparation process with high efficiency, less pollution and low energy consumption.)

1. A preparation process of furfural is characterized by comprising the following specific steps:

1) adding corncobs and a solid acid catalyst into a high-pressure reaction kettle, controlling the temperature and the pressure to start reaction, wherein maaldehyde and water are evaporated from a system;

2) condensing the mixture of the wool aldehyde and the water obtained in the step 1) through a condenser at the temperature of 10-25 ℃ and then layering to separate out the wool aldehyde on the lower layer;

3) adding potassium bicarbonate into the wool aldehyde separated in the step 2) under stirring for alkali washing, and performing alkali washing at 55 ℃ for 0.5 h;

4) and (3) carrying out reduced pressure distillation on the alkali-washed crude aldehyde in the step 3) at the pressure of-0.09 MPa and the temperature of 85-95 ℃, and continuously refining to obtain a furfural product.

2. The process for the preparation of furfural according to claim 1 wherein the solid acid catalyst in step 1) is a complex of aluminum phosphate and acetic acid or a complex of aluminum trichloride and acetic acid.

3. The process for preparing furfural according to claim 2 wherein the mass ratio of aluminum phosphate or aluminum trichloride to acetic acid in step 1) is 4-6: 1.

4. The process for preparing furfural according to claim 1 wherein the mass ratio of the solid acid catalyst to the corncobs in the step 1) is 0.03-1.5: 100.

5. The process for the preparation of furfural according to claim 1 wherein the pressure in step 1) is 0.8 to 1 MPa.

6. The process for the preparation of furfural according to claim 1 wherein the temperature in step 1) is 105 to 115 ℃.

7. The process for preparing furfural according to claim 1 wherein the corncob in step 1) has a particle size of 0.5 to 1.5 cm.

8. The process for the preparation of furfural according to claim 1 wherein step 3) is 0.11-0.15:1 of potassium bicarbonate and maxaldehyde.

Technical Field

The invention relates to the field of chemical production, in particular to a preparation process of furfural.

Background

Furfural is also called as furaldehyde (alpha-furaldehyde), molecular formula C₅H₄O₂(ii) a The name of English: furfurfural. The furfural pure product is colorless liquid and has special almond-like fragrance. The industrial product is brown liquid, and the color of the industrial product quickly changes into brownish black under the action of light, heat, air and inorganic acid. Melting point-38.7 deg.C, boiling point 161.7 deg.C, relative density 1.1594(20/4 deg.C). Slightly soluble in cold water, and soluble in organic solvent such as hot water, ethanol, diethyl ether, benzene, and acetone. Volatile, the vapor of which forms an explosive mixture with air. Furfural is an important organic chemical product, has active chemical property, can prepare numerous derivatives through reactions such as oxidation, condensation, etc., and chemical products directly or indirectly derived from furfural serving as a raw material can reach more than 1600, and are widely applied to industries such as medicine, pesticide, resin, daily chemicals, casting, textile, petroleum, etc.

The existing preparation process of furfural comprises a one-step method and a two-step method, wherein the hydrolysis of pentosan and the dehydration and cyclization reaction of pentose are respectively carried out in two different reactors. Because the optimal conditions for producing sugar by pentosan hydrolysis and generating furfural by pentose dehydration are different, the two reactions are separately carried out, so that the utilization rate of raw materials and the yield of furfural can be obviously improved. However, because the two-step method has high equipment investment, complicated operation and immature pentose dehydration process in the second step, the current furfural industrial production mainly adopts a one-step method, the one-step method has low equipment investment and simple operation, but the reaction temperature is increased during furfural preparation, so that the carbonization of saccharides in plants can promote the furfural to generate side reaction, the product yield is low (10-13 tons of corncobs are consumed for producing 1 ton of furfural product), the energy consumption in the production process is high (25 tons of steam are consumed for producing 1 ton of furfural, 150 tons of circulating cooling water are consumed for producing 1 ton of furfural), and the pollution of waste water and waste gas is serious (25 tons of waste water are generated for producing 1 ton of furfural). Therefore, the development of a furfural preparation process with high efficiency, less pollution and low energy consumption is of great significance.

Disclosure of Invention

Aiming at a series of problems in the existing furfural production process, the invention mainly solves the technical problem of providing a furfural synthesis method, which can improve the furfural production yield, reduce environmental pollution and reduce energy consumption.

In order to solve the technical problems, the technical scheme adopted by the application is as follows:

a preparation process of furfural comprises the following specific steps:

1) adding corncobs and a solid acid catalyst into a high-pressure reaction kettle, controlling the temperature and the pressure to start reaction, wherein maaldehyde and water are evaporated from a system;

2) condensing the mixture of the wool aldehyde and the water obtained in the step 1) through a condenser at the temperature of 10-25 ℃ and then layering to separate out the wool aldehyde on the lower layer;

3) adding potassium bicarbonate into the wool aldehyde separated in the step 2) under stirring for alkali washing, and performing alkali washing at 55 ℃ for 0.5 h;

4) and (3) carrying out reduced pressure distillation on the alkali-washed crude aldehyde in the step 3) at the pressure of-0.09 MPa and the temperature of 85-95 ℃, and continuously refining to obtain a furfural product.

Preferably, the solid acid catalyst in the step 1) is a compound of aluminum phosphate and acetic acid or a compound of aluminum trichloride and acetic acid;

preferably, the mass ratio of the aluminum phosphate or the aluminum trichloride to the acetic acid in the step 1) is 4-6: 1;

the mass ratio of the catalyst to the corncobs is preferably 0.03-1.5: 100;

preferably, the pressure in the step 1) is 0.8MPa to 1 MPa;

preferably, the temperature in the step 1) is 105-115 ℃;

preferably, the grain diameter of the corncob in the step 1) is 0.5-1.5 cm;

preferably, the ratio of potassium bicarbonate to maaldehyde is 0.11-0.15: 1.

The invention has the beneficial effects that: 1. the traditional furfural one-step process adopts sulfuric acid as a catalyst, has more side reactions such as sulfuric acid catalytic over-oxidation, carbonization and the like, is easy to generate micromolecular aldehyde and acid, has low reaction yield, has serious environmental pollution when the sulfuric acid-containing aldehyde slag is combusted, and produces SO by producing 1 ton of furfural₂The exhaust gas is about 36m³. Because acyl in the corncob fiber molecules is broken to generate acetic acid, aluminum phosphate and acetic acid or aluminum trichloride and acetic acid are compounded to be used as a catalyst, the catalytic effect is enhanced, the furfural yield is improved, the corrosion to equipment is low, no sulfuration gas and high-concentration acid-containing wastewater are generated, and the problem of environmental pollution caused by wastewater is solved. 2. The aldehyde slag is applied to the cogeneration, the problem of environmental pollution caused by the combustion emission of the sulfur-containing aldehyde slag in the traditional process is solved, and meanwhile, the method conforms to the relevant policies of national biomass energy development planning energy utilization and industry upgrading. 3. The refining of the furfural adopts a continuous distillation mode, and compared with the traditional process, the energy consumption is reduced.

Detailed Description