Method for preparing cellulose acetate from wheat straws

Abstract

The invention discloses a method for preparing cellulose acetate from wheat straws. The method comprises the following steps of: performing activating and bleaching pretreatment on the wheat straws; mechanically crushing; performing acetylation reaction; recovering the esterified liquid in a low-temperature condensation mode; separating acetylized products; and extracting the acetylized products with different components by using solvents to separate out the products such as cellulose triacetate, cellulose diacetate, acetylized hemicellulose, acetylized lignin and the like. The invention provides an economic and effective method for pretreating the wheat straws. By the method, the defect of the single catalyst in the traditional acetylation process is overcome; the cellulose acetate with high substitution degree and polymerization degree is prepared in a new catalyst system; and the wheat straws are utilized reasonably.

Description

technical field

[0001] The invention relates to the technical field of utilization of wheat straw renewable resources, in particular to a method for preparing cellulose acetate from wheat straw under the action of an improved catalyst system. Background technique

[0002] Natural cellulose raw material is the most abundant renewable organic matter on earth. China can produce about 1.145 billion tons of natural cellulose raw materials through photosynthesis every year, and the crop straw and hulls alone account for more than 700 million tons, of which wheat straw accounts for about 21%. In China, most straws are used as fuel or directly burned in the fields, which not only destroys the ecological balance, depletes soil fertility, causes a vicious cycle in agriculture, but also pollutes the environment and poses fire hazards.

[0003] With the emphasis on environmental protection and the utilization of renewable resources, the utilization of crop straw resources including whe...

Examples

Embodiment 1

[0024] Embodiment 1: 34g of pretreated wheat straw powder is placed in a reactor, and 150ml of esterification solution is added; 0.5% of mass sodium bisulfate, 1% of volume of hydrofluoric acid and 2% of volume of concentrated sulfuric acid are added as catalysts, Dilute with distilled water 1:1 before adding the concentrated sulfuric acid; Stir the reaction at 60°C for 2 hours to obtain a dark brown solution; Connect the outlet of the reactor to the condenser, continue heating and reflux for 0.5 hours, and collect Glacial acetic acid. The collection was stopped after the reactor was naturally cooled to room temperature.

[0025]The supernatant of the solution in the reactor was separated, and the precipitate was discarded. Distilled water was added to the supernatant to precipitate a precipitate, washed with water several times to neutrality, filtered by suction and dried in vacuum to finally obtain the acetylated product.

[0026] Solvent extraction of acetylated products ...

Embodiment 2

[0033] Embodiment 2: 34g of the pretreated wheat straw powder is placed in a reactor, and 150ml of esterification solution is added; 2% of mass sodium bisulfate, 2% of volume of hydrofluoric acid and 0.3% of volume of concentrated sulfuric acid are added as catalysts, Dilute with distilled water 1:1 before adding the concentrated sulfuric acid; Stir the reaction at 70°C for 2 hours to obtain a dark brown solution; Connect the outlet of the reactor to the condenser, continue heating and reflux for 0.5 hours, and collect Glacial acetic acid. The collection was stopped after the reactor was naturally cooled to room temperature.

[0034] The supernatant of the solution in the reactor was separated, and the precipitate was discarded. Distilled water was added to the supernatant to precipitate a precipitate, washed with water several times to neutrality, filtered by suction and dried in vacuum to finally obtain the acetylated product.

[0035] Solvent extraction of acetylated prod...

Embodiment 3

[0042] Embodiment 3: 34g of the pretreated wheat straw powder is placed in a reactor, and 150ml of esterification solution is added; 3% of mass sodium bisulfate, 3% of volume of hydrofluoric acid and 0.5% of volume of concentrated sulfuric acid are added as catalysts, Dilute with distilled water 1:1 before adding the concentrated sulfuric acid; Stir the reaction at 80°C for 2 hours to obtain a dark brown solution; Connect the outlet of the reactor to the condenser, continue heating and reflux for 0.5 hours, and collect Glacial acetic acid. The collection was stopped after the reactor was naturally cooled to room temperature.

[0043] The supernatant of the solution in the reactor was separated, and the precipitate was discarded. Distilled water was added to the supernatant to precipitate a precipitate, washed with water several times to neutrality, filtered by suction and dried in vacuum to finally obtain the acetylated product.

[0044] Solvent extraction of acetylated prod...

technical field

[0001] The invention relates to the technical field of utilization of wheat straw renewable resources, in particular to a method for preparing cellulose acetate from wheat straw under the action of an improved catalyst system. Background technique

[0002] Natural cellulose raw material is the most abundant renewable organic matter on earth. China can produce about 1.145 billion tons of natural cellulose raw materials through photosynthesis every year, and the crop straw and hulls alone account for more than 700 million tons, of which wheat straw accounts for about 21%. In China, most straws are used as fuel or directly burned in the fields, which not only destroys the ecological balance, depletes soil fertility, causes a vicious cycle in agriculture, but also pollutes the environment and poses fire hazards.

[0003] With the emphasis on environmental protection and the utilization of renewable resources, the utilization of crop straw resources including whe...

Examples

Embodiment 1

[0024] Embodiment 1: 34g of pretreated wheat straw powder is placed in a reactor, and 150ml of esterification solution is added; 0.5% of mass sodium bisulfate, 1% of volume of hydrofluoric acid and 2% of volume of concentrated sulfuric acid are added as catalysts, Dilute with distilled water 1:1 before adding the concentrated sulfuric acid; Stir the reaction at 60°C for 2 hours to obtain a dark brown solution; Connect the outlet of the reactor to the condenser, continue heating and reflux for 0.5 hours, and collect Glacial acetic acid. The collection was stopped after the reactor was naturally cooled to room temperature.

[0025]The supernatant of the solution in the reactor was separated, and the precipitate was discarded. Distilled water was added to the supernatant to precipitate a precipitate, washed with water several times to neutrality, filtered by suction and dried in vacuum to finally obtain the acetylated product.

[0026] Solvent extraction of acetylated products ...

Embodiment 2

[0033] Embodiment 2: 34g of the pretreated wheat straw powder is placed in a reactor, and 150ml of esterification solution is added; 2% of mass sodium bisulfate, 2% of volume of hydrofluoric acid and 0.3% of volume of concentrated sulfuric acid are added as catalysts, Dilute with distilled water 1:1 before adding the concentrated sulfuric acid; Stir the reaction at 70°C for 2 hours to obtain a dark brown solution; Connect the outlet of the reactor to the condenser, continue heating and reflux for 0.5 hours, and collect Glacial acetic acid. The collection was stopped after the reactor was naturally cooled to room temperature.

[0034] The supernatant of the solution in the reactor was separated, and the precipitate was discarded. Distilled water was added to the supernatant to precipitate a precipitate, washed with water several times to neutrality, filtered by suction and dried in vacuum to finally obtain the acetylated product.

[0035] Solvent extraction of acetylated prod...

Embodiment 3

[0042] Embodiment 3: 34g of the pretreated wheat straw powder is placed in a reactor, and 150ml of esterification solution is added; 3% of mass sodium bisulfate, 3% of volume of hydrofluoric acid and 0.5% of volume of concentrated sulfuric acid are added as catalysts, Dilute with distilled water 1:1 before adding the concentrated sulfuric acid; Stir the reaction at 80°C for 2 hours to obtain a dark brown solution; Connect the outlet of the reactor to the condenser, continue heating and reflux for 0.5 hours, and collect Glacial acetic acid. The collection was stopped after the reactor was naturally cooled to room temperature.

[0043] The supernatant of the solution in the reactor was separated, and the precipitate was discarded. Distilled water was added to the supernatant to precipitate a precipitate, washed with water several times to neutrality, filtered by suction and dried in vacuum to finally obtain the acetylated product.

[0044] Solvent extraction of acetylated prod...