Method for preparing nano cellulose by formic acid hydrolysis by using metal salt catalyst

A technology of nano-cellulose and metal salts, which is applied in the field of natural polymer material preparation, can solve the problems of high concentration of formic acid, difficulty in recovering inorganic acid, and long reaction time of formic acid, etc., and achieves easy control of the reaction, high crystallinity, and easy The effect of recycling

Active Publication Date: 2015-12-16
QINGDAO INST OF BIOENERGY & BIOPROCESS TECH CHINESE ACADEMY OF SCI
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Problems solved by technology

For example, in Carbohydrate Polymers, 2015, 133, 605-612, Li et al. disclose formic acid hydrolysis, but the reaction time of using formic acid alone is still long, and the concentration of formic acid is required to be high (98%)
For this reason, it is disclosed in Chinese invention patent 2014106492298 that adding a small amount of inorganic acid in the hydrolysis of formic acid can quickly stimulate the hydrolysis rate of formic acid and shorten the reaction time, but the recovery of inorganic acid is still relatively difficult

Method used

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  • Method for preparing nano cellulose by formic acid hydrolysis by using metal salt catalyst

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preparation example Construction

[0037] In step 1) of the method for preparing nanocellulose crystals according to the present invention, based on 100 parts by weight of the cellulose raw material, the metal salt addition is 0.5-30 parts by weight. When the metal salt addition is less than 0.5 parts by weight, the hydrolysis The promoting effect of the reaction is not obvious; and when the added amount of the metal salt is greater than 30 parts by weight, it may cause the metal salt to remain on the nanocellulose crystals, which will adversely affect the properties of the product.

[0038] The weight ratio of the added cellulose raw material to the added formic acid solution is 1:10-100, when the weight ratio is less than 1:10, that is, the amount of formic acid solution added is insufficient, and the reaction is not complete; and when the weight ratio is greater than 1:100, That is, an excessive amount of formic acid solution is not economical enough.

[0039] One of the advantages of the method for preparin...

Embodiment 1

[0042] Weigh 3g of dry bleached eucalyptus pulp and 0.3g of anhydrous ferric chloride into a 250mL round bottom flask, add 100mL of 88% (w / w) formic acid solution, and stir magnetically at 95°C for 6h. After the reaction, the flask was quickly placed in a cold water bath to cool to room temperature, and then the reaction mixture was transferred into a centrifuge tube and centrifuged at 8000 rpm for 5 min. The hydrolyzate can be directly returned to prepare the next batch of nanocellulose. The precipitated jelly is centrifuged and washed with distilled water until neutral, and the centrifuged product is freeze-dried to obtain nanocellulose crystals. The yield of nanocellulose obtained in the present embodiment is 75% (relative to the original dry bleached eucalyptus pulp), and the crystallinity is increased to 75% of nanocellulose (CNC) from 65% of the original pulp (Pulp) , the XRD patterns before and after hydrolysis are shown in the appendix figure 2 .

Embodiment 2

[0044] Weigh 2 g of dry bleached eucalyptus pulp and 0.1 g of anhydrous magnesium nitrate into a 250 mL round bottom flask, add 100 mL of 85% (w / w) formic acid solution, and stir magnetically at 80° C. for 6 h. After the reaction, the flask was quickly placed in a cold water bath to cool to room temperature, and then the reaction mixture was moved into a centrifuge tube and centrifuged at 5000 rpm for 10 min. The hydrolyzate can be directly reused to prepare the next batch of nanocellulose. The precipitated jelly is centrifuged and washed with distilled water until neutral, and the centrifuged product is freeze-dried to obtain nanocellulose crystals. The yield of nanocellulose obtained in this example is 78% (relative to the original dry bleached eucalyptus wood pulp), the width is 10-20nm, and the length is 100-300nm. image 3 Transmission electron microscope pictures in .

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Abstract

The invention relates to a novel method for preparing nano cellulose by hydrolyzing a cellulose raw material with formic acid by using a metal salt catalyst. In the method, the metal salt is utilized to catalyze the formic acid to hydrolyze the cellulose raw material, so that the hydrolysis efficiency is greatly enhanced, thereby lowering the formic acid concentration and further saving the cost. Besides, the method has the advantages of milder reaction conditions and controllable reaction, and is simple to operate.

Description

technical field [0001] The invention relates to the field of preparation of natural polymer materials, in particular to a new method for preparing nano-cellulose by using metal salts to catalyze formic acid to hydrolyze cellulose raw materials. Background technique [0002] In recent years, the preparation and application of nanocellulose have been extensively studied. In RSCAdvances, 2014, 4, 907-915, Mueller et al. reported that due to its special nanostructure and properties (for example, nanoscale, high specific surface area, high aspect ratio, low density, superior strength properties, low thermal expansion coefficient, Renewable and biodegradable, etc.), nanocellulose is widely used in nanomaterials, such as aerogels, biomedical materials, packaging materials, optoelectronic materials, and various nanocomposites. [0003] The most commonly used method for preparing nanocellulose is inorganic acid hydrolysis, such as sulfuric acid, hydrochloric acid, nitric acid, hydro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B15/02
Inventor 杜海顺李滨牟新东刘超龚文博
Owner QINGDAO INST OF BIOENERGY & BIOPROCESS TECH CHINESE ACADEMY OF SCI
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