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Method for recovery of molybdate in a molybdate-catalysed delignification of pulp with hydrogen peroxide

A technology of delignification and hydrogen peroxide, applied in metal/metal oxide/metal hydroxide catalysts, pulp dehydration, chemical instruments and methods, etc.

Inactive Publication Date: 2014-10-01
EVONIK DEGUSSA GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

A method of flotation of salts precipitated with dodecylamine was tested as an alternative to filtration but allowed a recovery of only 83% molybdate

Method used

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Examples

Experimental program
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Effect test

Embodiment

[0042] 831.3 g of eucalyptus pulp, corresponding to 200 g of pure dry pulp, having a kappa number of 13.0, an ISO brightness of 54.0% and a yellow value of 30.3, were treated with water, 0.5% by weight of hydrogen peroxide and 500 ppm of molybdenum in the form of sodium molybdate (Based on pure dry pulp) to a solids content of 10% by weight, and the pH was adjusted to pH 3.0 with sulfuric acid. The mixture was heated in a plastic bag at 90° C. for 120 minutes on a water bath. Water is then added to obtain a suspension with a solids content of 4% by weight, and the pulp is filtered on a suction filter provided with filter paper. The treated pulp had a kappa number of 5.2, an ISO brightness of 53.0% and a yellowness value of 31.1. The filtrate obtained had a pH of 3.7. The filtrate contained 19 ppm molybdenum, corresponding to 95% of the amount used.

[0043] In a 1000ml glass beaker, 6.0g of cationically modified bentonite SD-2 (Elementis Specialties) was added to 600 g of...

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Abstract

In a delignification of pulp with hydrogen peroxide catalysed with molybdate, molybdate can be recovered by bringing the aqueous solution containing molybdate into contact with a carrier material that comprises a layered silicate ion-exchanged with a quaternary ammonium salt at a pH value ranging between 2 and 7 and subsequent flotation, without the need to add a tenside for the flotation.

Description

field of invention [0001] The present invention relates to a method for the recovery of molybdate in molybdate-catalyzed delignification of pulp using hydrogen peroxide. Background technique [0002] Bleaching of pulp is usually carried out in alkaline media with hydrogen peroxide, since free radicals leading to undesired secondary reactions such as degradation of cellulose are formed in acidic media at high temperatures. However, delignification with hydrogen peroxide as well as bleaching can also be accomplished under acidic conditions when appropriate catalysts are used. [0003] US 4,427,490 describes the delignification and bleaching of kraft pulp with hydrogen peroxide in acidic medium, catalyzed by sodium tungstate or sodium molybdate. [0004] WO 2009 / 133053 describes a process for the recovery of molybdate or tungstate from aqueous solutions suitable for the recovery of molybdate in molybdate or tungstate catalyzed delignification of pulp using hydrogen peroxide o...

Claims

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Application Information

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IPC IPC(8): D21C9/16B01J20/12B01J38/00B01J45/00C01G39/00C22B34/34C22B3/24C22B3/42
CPCD21C11/005B01J20/3204B01J20/3248C01G39/003B01J20/10B01J23/28D21C9/18D21C9/16
Inventor T·迪茨B·霍普夫R·格里默尔
Owner EVONIK DEGUSSA GMBH
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