Processes for pretreating and purifying a cellulosic material

a cellulosic material and purification technology, applied in the field of purification of cellulosic products from raw cellulosic materials, can solve the problems of incompatible with certain industrial uses, high cost of such pulps, and inability to meet the requirements of certain industrial uses

Inactive Publication Date: 2016-02-11
CELANESE ACETATE LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0016]In another embodiment, the present invention is directed to a process for purifying a cellulosic material, comprising: subjecting the cellulosic material to a dilute acid pretreatment to form a pretreated cellulosic material; extracting hemicellulose and degraded cellulose from the pretreated cellulosic material with an extractant to form an extraction mixture; wherein the extractant comprises a cellulose solvent and a co-solvent and wherein the cellulose solvent is selected from the group consisting of an ionic liquid, an amine oxide, and combinations thereof; and separating the extracted hemicellulose from the extraction mixture to form a cellulosic product comprising less hemicellulose than the pretreated cellulosic material.
[0017]In another embodiment, the present invention is directed to a process for purifying a cellulosic material, comprising: delignifying the cellulosic material to form a wet cellulosic material comprising at least 5 wt. % water; subjecting the wet cellulosic material to a d

Problems solved by technology

Acetate-grade pulps are specialty raw materials produced in commercial pulp processes, but the cost for such pulps is high.
Paper grade pulp contains a high amount of impurities, such as hemicellulose, rendering it incompatible with certain industrial uses, such as making cellulose acetate flake or tow.
However, DMDO is not currently commercially available due to its instability.
Therefore, it is not an ideal solvent for pr

Method used

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  • Processes for pretreating and purifying a cellulosic material
  • Processes for pretreating and purifying a cellulosic material
  • Processes for pretreating and purifying a cellulosic material

Examples

Experimental program
Comparison scheme
Effect test

example a

Water Pretreatment with Single Extraction (Samples 1 Through 11)

[0153]A commercially available hardwood paper grade pulp from a species indigenous to the southeastern United States comprising 74.2% glucan, 19% xylan, and 0.9% mannan as determined by sugar analysis was mixed with water in a pulp to water ratio of 1:10 and then heated to the temperature shown in Table 7 below for 30 to 60 minutes. The pulp was then collected by filtration, washed with water, and dried in a hood.

[0154]After the pulp had been dried, it was then uniformly mixed with an extractant comprising 21 wt. % EMIMAc / ACN at the solid / liquid ratio as shown in Table 7 below. The mixture was sealed in a vial and heated to 95° C. for 1 hour. The mixture was then centrifuged at 51 g force (8000 rpm) for 5 minutes to remove the liquid from the pulp by using a centrifuge tube with a metal filter in the middle. The pulp was then washed with 20 mL water four times, with centrifuging at 51 g force (8000 rpm) for 5 minutes be...

example b

Dilute Acetic Acid Pretreatment with Single Extraction (Samples 33 Through 40)

[0166]A commercially available hardwood paper grade pulp from a species indigenous to the southeastern United States comprising 74.2% glucan, 19% xylan, 0.9% mannan as determined by sugar analysis, was mixed with a dilute glacial acetic acid solution having a strength shown in Table 8 below in a weight ratio of pulp to dilute acid solution of 1 to 40. The mixture was heated to a temperature of 120° C. in an autoclave for 1 hour. The pulp was then collected by filtration, washed with water, and dried in a hood.

[0167]After the pulp had been dried, it was uniformly mixed with an extractant comprising 21 wt. % EMIMAc / ACN at the solid / liquid ratio as shown in Table 8 below. The mixture was sealed in a vial and heated to 95° C. for 1 hour. The mixture was then centrifuged at 51 g force (8000 rpm) for 5 minutes to remove the liquid from the pulp by using a centrifuge tube with a metal filter in the middle. The pu...

example c

Dilute Sulfuric Acid Pretreatment with Single Extraction (Samples 47 Through 57)

[0172]A commercially available hardwood paper grade pulp from species indigenous to the southeastern United States comprising 74.2% glucan, 19% xylan, 0.9% mannan as determined by sugar analysis, was combined with a dilute sulfuric acid solution having a pH shown in Table 9 below in a weight ratio of pulp to dilute acid solution of 1 to 40. The mixture was heated to a temperature of 120° C. in an autoclave for 1 hour. The pulp was then collected by filtration, washed with water, and dried in a hood.

[0173]After the pulp had been dried, it was uniformly mixed with an extractant comprising 21 wt. % EMIMAc / ACN at the solid / liquid ratio as shown in Table 9 below. The mixture was sealed in a vial and heated to 95° C. for 1 hour. The mixture was then centrifuged at 51 g force (8000 rpm) for 5 minutes to remove the liquid from the pulp by using a centrifuge tube with a metal filter in the middle. In Samples 47, ...

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Abstract

A process for treating a cellulosic material comprising pretreating the cellulosic material and then extracting the cellulosic material with an extractant to selectively extract hemicellulose therefrom and separating the extracted hemicellulose to form a cellulosic product comprising less hemicellulose than the cellulosic material. The extractant comprises a cellulose solvent and a co-solvent. The cellulosic product advantageously retains its cellulosic fiber morphology. The processes involve separating and recovering the hemicellulose and separating and recycling various process streams employed in the process.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority to U.S. Provisional No. 62 / 033,442, filed Aug. 5, 2014, the entirety of which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to processes for obtaining a cellulosic product from a raw cellulosic material. In particular, the present invention relates to processes for converting raw cellulosic materials into pulp, pretreating the pulp, and then purifying the pretreated pulp to produce purified pulp comprising cellulose and having reduced hemicellulose content.BACKGROUND OF THE INVENTION[0003]Cellulose is typically obtained from wood pulp and cotton and may be further modified to create derivatives including regenerated cellulose, cellulose ethers, cellulose esters and cellulose nitrate, among others. Cellulose derivatives have a variety of commercial uses. For example, cellulose acetate is the acetate ester of cellulose and is used for a variety of prod...

Claims

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Application Information

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IPC IPC(8): D21H17/14D21H11/00D21H17/07
CPCD21H17/14D21H11/00D21H17/07C08B37/0057C08H8/00
Inventor LI, BINALLEN, LESLIEARORA, DINESHBANSAL, PRABUDDHABOATWRIGHT, MONICABUNDREN, CHRISTOPHER M.COMBS, MICHAEL T.FALLON, DENIS G.LI, RONGFUMEHTA, JAYPAN, TIANSHU
Owner CELANESE ACETATE LLC
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