Preparation method of cellulose diacetate

Abstract

The invention discloses a preparation method of cellulose diacetate. The method prepares the cellulose diacetate by synchronously adding cellulose, acetic acid, an ionic liquid, a catalyst and an acetylation reagent in a reaction device to perform acetylation reaction, wherein the reaction time is 2-12 hours; the reaction temperature is 60-120 DEG C; the catalyst is sulfonation solid acid Amberlyst15; the acetylation reagent is acetic anhydride or acetic chloride; the dosage ratio of the cellulose to the ionic liquid is (0.025-0.05) g/ml; the mol ratio of the catalyst to the cellulose is (0.05-0.1):1; the mol ratio of the acetylation reagent to the cellulose is (3-6):1; solid catalyst is recovered through solid-liquid separation; after supernate is finished, the product can be separated and the ionic liquid is recovered. The method can synthesize the cellulose diacetate with excellent dissolving performance by one step; the catalyst and the reaction medium both can be recovered and recycled, so that the corrosion due to the traditional strong acid catalysis and the environmental pollution caused by the organic volatility solvent are overcome.

Description

technical field [0001] The invention belongs to the technical field of resource utilization of cellulose, in particular to a preparation method of cellulose diacetate. Background technique [0002] With the depletion of fossil energy and the increasing concern of human beings on environmental issues, the search for renewable clean energy has become the focus of attention all over the world. Natural lignocellulose, as the most abundant renewable resource in nature, has attracted much attention. Lignocellulose widely exists in various agricultural wastes (rice straw, wheat straw, rice husk, cotton straw, hemp straw, bagasse, etc.), and the annual production of crop straw in the world is about 2.9×1010t. It is estimated that if the development of energy forestry and the recycling of waste lignocellulose are carried out simultaneously, more than 1 / 3 of fuel alcohol can be replaced every year. [0003] Cellulose acid is one of the earliest commercially produced compounds among c...

AI Technical Summary

Problems solved by technology

Cellulose acetylation products with a degree of substitution between 2 and 2.5 are usually called cellulose diacetate. Because cellulose diacetate has good thermoplasticity and solubility properties, it is widely used in the manufacture of cigarette filters, medical filter materials, textiles, etc. , plastic products, film and liquid crystal materials, etc., are internationally recognized and non-toxic and harmless products that have not yet found alternative materials

Cellulose diacetate is not easy to be directly prepared by acetylation of cellulose. It is usually obtained by partial saponification and hydrolysis of cellulose triacetate, a product of complete acetylation of cellulose. There are disadvantages such as complicated process and uneven product properties.

[0005] At present, there are few studies on the application of ionic liquids in the acetylation of cellulose, and they mainly focus on the homogeneous reaction of cellulose. After the reaction, the catalyst is difficult to separate from the reaction system, which makes it difficult to recover and recycle both the solvent and the catalyst. use