Preparation method of cellulose acetate butyrate with high butyryl content

The invention discloses a preparation method of cellulose acetate butyrate with high butyryl content. The preparation method includes steps of performing ester exchange on smashed cellulose after being activated by acetic acid and butyrate alkyl ester under the catalyst of sulfuric acid, and generating the cellulose acetate butyrate with high butyryl content; when the ester exchange reaction is carried out, the reaction is promoted to carry out in positive direction through alcohol generated from rectification. In the cellulose acetate butyrate prepared by the method, acetyl content is 1-2 wt%, and butyryl content is 50-53 wt%. The preparation method applies non-corrosive esterifying agent, and excessive esterifying agent can be recycled; thus the production cost is greatly reduced and the preparation method is applicable to the industrial production.