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4246167 
Journal Article 
A study of transition metal polyoxoanions as bleach catalysts in delignification of wood pulp 
Dey, KC; Sharma, V 
2011 
Yes 
Journal of the Indian Chemical Society
ISSN: 0019-4522 
88 
9 
1327-1330 
WOS:000295300400001 
The field of polyoxometalates (POMs), although a mature field, continues to attract the attention of new researchers. The majority applications of POMs are found in the area of catalysis. This review is based on the patent and refereed literature of applied research which summarizes the applications of POMs as an oxidative bleach catalyst in delignification of wood pulp.



The common process for bleaching of wood pulp uses chlorine which reacts with chromophores and residual lignin to form hazardous byproducts which pose a serious threat to the environment. The chemistry of totally free chlorine bleaching method is oxygen based. In addition to oxygen gas, hydrogen peroxide, ozone, per-acids treatments are used. During the past two decades, the uses of elemental chlorine free bleaching agent have been widely studied.



One alternative for improving the performance of oxygen chemicals is the application of catalysts. POMs used as reversible oxidants, offer a safe alternative to chemical chlorine.



An environmentally benign new technology based on salts of polyoxometalates and oxygen is being developed to bleach wood pulp for use in the manufacture of paper.



The goal of bleaching is to remove lignin from the pulp for use in paper manufacturing process. The process of bleaching is to remove lignin from the pulp without a negative effect on cellulose, for which delignification should be performed in highly selective manner.



The researchers have focused on POMs, used as catalysts in aerobic conditions of oxidative delignification. This review constitutes a general approach to the design of soluble transition metal catalyst for aerobic oxidation in water.



In this paper, the function of transition metal polyoxoanions as oxidative catalysts is vividly reviewed. 
Delignification; bleaching; POMs; wood pulp