Method of producing cellulose intermediate product

FIELD: chemistry.

SUBSTANCE: water suspension of crushed aspen wood is put into a flow reactor and ozonised. Ozonation is carried out with concentration of ozone in the ozone-oxygen mixture equal to 90 mg/l, gas flow rate equal to 2-4 l/h and temperature of 20C and hydromodulus between 0.1:1.0 and 1.6:1.0.

EFFECT: high quality of the cellulose intermediate product, low consumption of reagents, high ecological cleanness of the process.

5 ex, 2 tbl

 

The invention relates to the field of chemical processing of wood and can be used in the pulp and paper industry to obtain cellulose semi. Thus obtained semi-finished product can be used as adsorbent for absorbing water vapor and other compounds, and also as the basis for the synthesis of chemically modified carbohydrate and lignouglevodnyh materials.

The essence of the invention lies in the fact that shredded hardwood subjected to ozonation at a temperature of 20C. the Method allows to obtain a cellulose material with a high cellulose content and low lignin content.

To obtain a pulp semi-finished hardwoods traditionally used cooking processes. A method of obtaining cellulose semi by cooking wood chips with a mixture of 90%acetic acid and 30%hydrogen peroxide in the presence of a catalyst is sulfuric acid [SU 821614, 15.04.81]. The disadvantage of this method is the low yield of the target product, the two-phase process, a significant consumption of hydrogen peroxide and sulfuric acid catalyst.

Closest to the claimed invention is a one-step method for cellulose semi-finished product by cooking shredded aspen wood is a mixture of 37% hydrogen peroxide and 30% acetic acid, taken in a molar ratio of 0.3-0.5 at a water ratio of 10:1 and a temperature of 120-140C for 2-5 hours in the presence of sulfuric acid in the amount of 1.5 to 2.5% by weight of absolutely dry wood [EN 2150538, 10.06.2000]. The disadvantage of this method is the use of a sulfuric acid catalyst, because it promotes the degradation of carbohydrates of wood, which reduces the content of cellulose in the cellulose material. The disadvantage of this method is also a significant consumption of reagents (hydrogen peroxide and acetic acid) and sulfuric acid catalyst, resulting in the contamination of wastewater.

Known patents relating to the use of ozone as an environmentally friendly reagent in the process of bleaching lignocellulosic materials [US Patent 5164043, 17.11.1992]. In some countries, the ozone is used in paper production as one of delignification agents on the stage of the bleaching of pulp [J.Rounsaville, R.G.Rice. Ozone Science & Engineering 18, 549 (1997)].

The problem solved by the claimed invention lies in the creation of clean technology to obtain high yield pulp material with high cellulose content, low content of lignin, as well as allowing to reduce the specific consumption of reagents when it is received.

The problem is solved by ozonation wood is aspen, in water suspension. Ozonation water suspension shredded aspen wood is carried out in a flow reactor at a concentration of ozone in the ozone-oxygen mixture of 90 mg/l, flow rate of gas 2-4 l/h and a temperature of 20C at a water ratio from 0.1:1.0 to 1.6:1.0 in.

The main feature of the claimed technical solution is used as a reagent ozone. Ozone is a strong oxidant, the only product of the transformation which is oxygen; ozone is characterized by a high reactivity towards aromatic compounds, which promotes the selective oxidation of lignin of wood. The process under different water ratio can be optimized from the point of view of the quality of the pulp cake mix and specific consumption of reagent - ozone and solvent - water. Use at the exit of the catalytic reactor cartridge ozone decomposition [EN 2077946, 27.04.97] avoids the emission of unreacted ozone in the atmosphere and improve environmental safety of the process.

The essence of the proposed method of obtaining cellulose semi illustrated by the following examples.

Example 1 (Table 1). To 1 g of absolutely dry shredded aspen wood (particle size 0,315-0,63 mm) add 0.1 g of water, put this suspension flow reactor and passed an ozone-oxygen mixture with ozone concentration of 90 mg/L. Gas flow rate 4 l/h, temperature 20C. Ozonation spend as long as you do not stop the absorption of ozone. Output cellulose semi - 82%, cellulose content is 60%, the content of residual lignin - 21,3%.

Example 2. Ozonation carried out under the same conditions as in example 1, but at a water ratio of 0.3:1.0 in. Output cellulose semi - 62%. Cellulose content in it is 67%, the content of residual lignin was 4.8%.

Example 3. Ozonation carried out under the same conditions as in examples 1-2, but when the water ratio of 0.6:1.0 in. Output cellulose semi - 55%. Cellulose content in it - 75%, the content of residual lignin of 3.5%.

Example 4. Ozonation carried out under the same conditions as in examples 1-3, but when the water ratio of 1.0:1.0 in. Output cellulose semi - 55%. Cellulose content in it - 75%, the content of residual lignin of 3.1%.

Example 5. Ozonation carried out under the same conditions as in examples 1-3, but when the water ratio of 1.6:1.0 in. Output cellulose semi - 50%. Cellulose content in it - 78%, the content of residual lignin is 1.7%.

Examples 6, 7 of table 2 shows that at a flow rate of 2 l/h with increasing water ratio increases the flow of ozone; the degree of delignification increases from 15.8% to 81%.

Examples 8, 9 of table 2. When the water ratio of 0.6:1,0-1,0:1,0 consumption of ozone 1,1-1,3 g of ozone per gram of absolutely dry d is avecina with the degree of delignification 86,2-87,7%.

Example 10 of table 2. When the water ratio of 1.6:1.0 - degree of delignification of 93.3%, the consumption of ozone 3.0 g of ozone per gram of wood.

Thus, when the water ratio of 0.1:1.0 is the high yield pulp semi-finished product, but the high content of lignin (21,3%) and low cellulose content. Increasing the water ratio higher values 1,0:1,0 leads to lower output cellulose semi-due to partial degradation of carbohydrates in the wood that is accompanied by a significant increase in the consumption of ozone.

To obtain a pulp of the material with a yield of 55% with a high content of cellulose (75%) and moderate consumption of ozone ozonation aspen wood is useful to water ratio of 0.6:1,0-1,0:1,0. The degree of delignification in this is 86.2-87,7%.

Table 1
The effect of water ratio on the yield of cellulose semi
The ozone concentration in the ozone-oxygen mixture of 90 mg/l, the rate of gas flow of 4 l/h, temperature 20C.
ExampleThe water ratioThe output of semi-finished product, %**The content of lignin in the material, %* The cellulose content in the material, %
10,1:1,08221,360
20,3:1,0624,867
30,6:1,0553,575
41,0:1,0553,175
51,6:1,0501,778
* from the mass of absolutely dry cake mix
** on the mass of the ASD wood

Table 2.
The effect of water ratio on the flow of ozone and the degree of delignification of the pulp cake mix
ExampleThe water ratio Consumption of ozone g ozone/g ASDThe degree of delignification, %
60,1:1,00.115,8
70,3:1,00.981,0
80,6:1,01.186,2
91,0:1,01.387,7
101,6:1,03.093,3
The ozone concentration in the ozone-oxygen mixture of 90 mg/l, the rate of gas flow of 2 l/h, temperature 20C.

The method of obtaining cellulose semi by ozonation shredded aspen wood in the form of an aqueous suspension, wherein the pulp semi-finished product is produced by ozonation of wood in a flow reactor at a flow rate of gas 2-4 l/h, the concentration of ozone in the ozone-oxygen mixture of 90 mg/l, the water ratio from 0.1:1.0 to 1.6:1.0 and a temperature of 20C.



 

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2 tbl, 24 ex

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3 tbl, 22 ex

FIELD: cellulose derivatives production.

SUBSTANCE: invention is intended to be employed in paper-and-pulp industry in sulfate or natron cellulose manufacture process. Coniferous or foliferous wood is cooked in alkali solution at elevated temperature and pressure in presence of anthraquinone as delignification catalyst, the latter being product obtained after acylation of phthalic anhydride with benzene, which is added in 0.01-0.1% excess to dry wood, cooking being carried out in a way that 12-16% of active alkali based on the weight of dry wood is consumed.

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4 tbl, 3 ex

FIELD: cellulose derivatives production.

SUBSTANCE: invention is intended to be employed in paper-and-pulp industry in sulfate or natron cellulose manufacture process. Coniferous or foliferous wood is cooked in alkali solution at elevated temperature and pressure in presence of anthraquinone as delignification catalyst, the latter being product obtained after acylation of phthalic anhydride with benzene, which is added in 0.01-0.1% excess to dry wood, cooking being carried out in a way that 12-16% of active alkali based on the weight of dry wood is consumed.

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4 tbl, 3 ex

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EFFECT: high parameters of delignification process; enhanced economical efficiency; reduction of toxic emissions.

2 tbl

FIELD: production of fibrous half-finished products at different degree of delignification; wood-pulp and paper industry.

SUBSTANCE: cellulose-containing vegetable material is subjected to boiling at higher sulfidity of boiling solution, up to 100%. Used as sulfide-containing component are alkaline wastes of oil desulfurization processes which contain inorganic compounds, including sodium sulfide at concentration up to 120 g/l in Na2O terms and residual organic compounds in form of sulfur-containing hydrocarbons C5-C6 and phenolates at concentration up to 15 g/l. Boiling is carried out at 130-160°C.

EFFECT: high parameters of delignification process; enhanced economical efficiency; reduction of toxic emissions.

2 tbl

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