Processes for Purifying a Cellulosic Material

a cellulosic material and purification technology, applied in pulp by-product recovery, pulp liquor regeneration, papermaking, etc., can solve the problems of high cost of such pulps, incompatible with certain industrial uses, and inability to commercialize dmdo, so as to reduce the content of hemicellulos

Inactive Publication Date: 2014-11-06
ACETATE INT LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010]The present invention is directed to processes for purifying a cellulosic material, e.g., wood pulp or paper grade wood pulp, and preferably for recovering hemicellulose therefrom. In one embodiment, for example, the invention is to a process for purifying a cellulosic material, comprising extracting hemicellulose from the cellulosic material with an extractant to form an intermediate cellulosic material having a reduced hemicellulose content; concentrating the intermediate cellulosic material to form a concentrated cellulosic material having an increased solids content; and recovering the separated hemicellulose. The concentrated cellulosic material preferably is dried to recover a finished cellulosic product. The extracting hemicellulose step preferably comprises directing the cellulosic material and the extractant to an extractor; extracting hemicellulose from the cellulosic material in the extractor to form an extraction mixture; and filtering and washing the extraction mixture with an extractant wash to form the intermediate cellulosic material and an extraction filtrate.

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, currently, DMDO is not commercially available due to its instability.
Therefore, it is not an ideal solvent for producing large quantities of high α-cellulose content pulp.
However, in order to turn cellulose containing materials into glucose, the methods disclosed in these references result in breaking down the cellulose molecules, making them unsuitable for use as starting materials to make cellulose derivatives.
This method results in the complete dissolution of the cellulose and destruction of the fiber morphology of the cellulose.

Method used

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  • Processes for Purifying a Cellulosic Material
  • Processes for Purifying a Cellulosic Material
  • Processes for Purifying a Cellulosic Material

Examples

Experimental program
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Effect test

example 1

[0106]A cellulosic material comprising 74.8 wt. % cellulose, 18.7 wt. % hemicellulose and 6.5 wt. % water was fed to an extraction unit. Separately, an extractant comprising 3.5 wt. % EMIM Ac and 96.5 wt. % DMSO was fed to the extraction unit. The extraction was conducted at a temperature of 90-110° C. and a pressure of 90−110 kPa. An extraction mixture comprising 3.6 wt. % cellulose, 0.89 wt. % hemicellulose, 0.31 wt. % water, 3.3 wt. % ionic liquid and 91.9 wt. % DMSO was removed from the extractor and sent through a vacuum filter and washed with an extractant wash to remove an extraction filtrate comprising extractant and hemicellulose. The extractant wash was water and was fed at a 10:1 mass ratio of water to pulp. The washed cellulosic material, e.g., the intermediate cellulosic material, comprised 24.5 wt. % cellulose, 0.5 wt. % hemicellulose and 75 wt. % water. The intermediate cellulosic product was then de-liquored to concentrate the intermediate cellulosic product. The res...

example 2

[0109]The finished cellulosic product and the finished hemicellulose product were prepared as in Example 1, except that the extraction process was completed in a 2-stage counter-current operation. The extraction time was dropped to 60 minutes at temperature of 90° C. for dissolving the same amount of hemicellulose, which was indicated by the UV absorbance value of 1.2 at 277 nm wavelength, or equivalently 2.8 wt. % hemicellulose.

example 3

[0110]The finished cellulosic product and the finished hemicellulose product were prepared as in Example 1, except that the extractant wash comprised 90 wt. % acetic acid and 10 wt. % water. The value of UV absorbance at 277 nm for the final pulp is 0.98, or equivalently 1.9 wt % hemicellulose.

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Abstract

A process for treating a cellulosic material comprising 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 APPLICATIONS[0001]This is a non-provisional of U.S. App. No. 61 / 819,150, filed May 3, 2013, and to U.S. App. No. 61 / 862,917, filed Aug. 6, 2013, the entire contents and disclosures of which are incorporated herein.FIELD OF THE INVENTION[0002]The present invention relates generally to processes for purifying a cellulosic material. In particular, the present invention relates to processes for extracting and recovering hemicellulose from pulp and producing a 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 products, including textiles (e.g., l...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21C3/20D21C11/00
CPCD21C11/0007D21C3/20D21C9/005D21C9/02
Inventor FALLON, DENIS G.GARRETT, THOMAS S.KIZER, LAWTONLI, BINLI, RONGFUMEHTA, JAYPAN, TIANSHUTU, XIAOYANALLEN, LESLIEARORA, DINESHBANSAL, PRABUDDHACOMBS, MICHAEL T.
Owner ACETATE INT LLC
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