Process for preparing furfural by using agricultural by-products of high and crude fiber plants

Abstract

The invention discloses a process for preparing furfural by using agricultural by-products of high and crude fiber plants. The process includes the steps of 1) conducting pretreatment of raw materials; 2) hydrolyzing pretreated raw materials in a hydrolyzing tank, and using an acid catalyst formed by mixing sulfuric acid and phosphoric acid during the hydrolytic process; 3) introducing high-temperature steam into the hydrolyzing tank, heating up the hydrolyzing tank, and conducting gap stripping for hydrolysis products of furfural; and 4) feeding gas stripped furfural to into a furfural phase splitter to obtain coarse furfural and furfural residues. According to the process, the acid catalyst combining the sulfuric acid and the phosphoric acid is used for hydrolyzing the raw materials, and the hydrolytic process is assisted by ultrasonic treatment simultaneously, so that the productivity of the furfural is improved, the residue amount of the sulfuric acid is a little, the production of sulfur oxides in the subsequent activating process of furfural residues is reduced, and the environmental pollution is reduced. Besides, the invention also provides a process for producing activated carbon adsorbents by using the furfural residues. The process includes the steps of drying the furfural residues, screening, roasting, hardening activating and steam curing, the obtained activated carbon specific surface is large, the iodine value is high and the adsorption capacity is high.

Description

[0001] Technical field [0002] The invention relates to the technical field of furfural preparation, in particular to a method for preparing furfural and activated carbon from high-crude fiber plant agricultural and sideline products. [0003] Background technique [0004] Furfural is an important organic compound made from agricultural and sideline products. It has a wide range of uses, such as rubber, plastics, synthetic fibers, pesticides, medicines, coatings, chemical reagents, etc. [0005] At present, most of furfural is obtained by hydrolyzing polypentose from crops containing polypentane bran. Many crops’ stems, barks and seed husks contain polypentose, which can be used as raw materials for furfural production, such as corn cobs, cottonseed husks, rice husks and bagasse. Among them, corn cobs have a higher aldehyde yield. , The theoretical aldehyde rate is 19%. Therefore, acid hydrolysis of corncobs or other agricultural by-products is currently used to produce furfural. ...

AI Technical Summary

Problems solved by technology

The commonly used method nowadays is to use the waste residue as boiler fuel, but the acid content in the waste residue is high, the calorific value is low, it is not easy to burn, and the sulfur-containing compounds produced during the combustion process are also very easy to cause the boiler to be corroded and damaged.

Due to the high carbon content of furfural residue, which is more than 40% (mass fraction), it is a good raw material for preparing activated carbon. In recent years, the industry has tried to use chemical methods to make furfural residue into activated carbon, but due to the following factors, The quality of the activated carbon produced does not meet the industrial requirements: 1) furfural waste residue is the acid hydrolysis product of corn cob, and the cellulose structure of corn cob is severely damaged during the hydrolysis process, which makes the chemical activator harmful to the cellulose in corn cob The swelling and erosion effects of the corn cob are reduced, which affects the post-activation pore-forming process; 2) The corn cob is decomposed into particles of different sizes during the hydrolysis process, and the particle size varies greatly. Uniformly promulgated in the material, if screening and grading will greatly reduce the production efficiency and the process is complicated, the wet sticky and acidic furfural residue is difficult to break, even if it is broken, the cost is unacceptable for industrial production; 3) corn is Plants with high silicon content, coupled with lax raw material sources and high impurities such as soil, lead to the presence of high silicon, which has a significant impact on the quality of activated carbon; 4) A large amount of residual sulfuric acid will release sulfur when furfural slag is activated at high temperature oxides, causing pollution

Therefore, the processing method of existing furfural waste residue needs to be improved