Integrated Processes for Purifying a Cellulosic Material

a cellulosic material and integrated technology, applied in pulp by-product recovery, pulp liquor regeneration, papermaking, etc., can solve the problems of high cost of such so-called cellulose produced in commercial pulp processes, incompatible with certain industrial uses, and inability to achieve dmdo. to achieve the effect of reducing the cost of dmdo

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

AI Technical Summary

Problems solved by technology

The cost of such so-called cellulose produced in commercial pulp processes 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 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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  • Integrated Processes for Purifying a Cellulosic Material
  • Integrated Processes for Purifying a Cellulosic Material
  • Integrated Processes for Purifying a Cellulosic Material

Examples

Experimental program
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Effect test

example 1

[0159]A wet pulp, simulating a wet pulp from a kraft or sulfite pulping process, was pre-extraction washed with DMSO to reduce the water content. Excluding any DMSO from this pre-extraction wash, a pulp 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...

example 2

[0162]The finished cellulosic product and the finished hemicellulose product were prepared as in Example 1, except that the extraction process was completed in 82-stage counter-current operation. The extraction time was dropped to 60 minutes at a 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

[0163]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 converting a starting material to a purified pulp material, comprising removing lignin from a starting material to form a wet pulp comprising at least 5 wt. % water, extracting hemicellulose from the wet pulp with an extractant, and separating the extracted hemicellulose from the extraction mixture to form a cellulosic product comprising less hemicellulose than the wet pulp. The extractant comprises a cellulose solvent and a co-solvent. The cellulosic product advantageously retains its cellulosic fiber morphology. The process involves separating and recovering 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. Provisional Appl. Nos. 61 / 819,150, filed May 3, 2013; 61 / 862,917, filed Aug. 6, 2013; 61 / 862,914, filed Aug. 16, 2013; 61 / 873,764, filed Sep. 4, 2013; and 61 / 933,203, filed Jan. 29, 2014, the entireties of which are 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 an integrated process for converting a raw cellulosic material into a pulp and then purifying the pulp to produce 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 variet...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21C3/20
CPCD21C3/20D21C9/005D21C9/02D21C11/0007
Inventor FALLON, DENIS G.LI, BINLI, RONGFUMEHTA, JAYPAN, TIANSHUSHER, JAIMESALLEN, LESLIEARORA, DINESHBOATWRIGHT, MONICABUNDREN, CHRISTOPHER M.COMBS, MICHAEL T.
Owner CELANESE ACETATE LLC
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