COPPER POLYPYRIDINYL COMPLEXES AS CATALYSTS FOR NATIVE LIGNIN OXIDATION BY OXYGEN
The objective of this work was to find Cu(II) complexes with different polypyridinyl ligands which could selectively catalyse native lignin oxidation by oxygen. A ligand screening was conducted on the oxygen oxidation of the veratryl alcohol used as lignin model in alkaline conditions. The selected complexes are made of terpyridines, daphen, phenanthroline or substituted phenanthrolines as ligands. The reaction of veratryl alcohol was followed by HPLC. Depending on the nature of the complex, the alcohol disappearance varied from 3 to 57％ under the selected conditions. These figures were in close correlation with the kappa number drop observed on a native lignin containing substrate treated with the same complexes, except for the copper-daphen complex which was active on veratryl alcohol but not on the pulp substrate. Hydrogen peroxide was also used as oxidant instead of oxygen for the oxidation of the veratryl alcohol since it is known that hydrogen peroxide is formed during oxygen treatment. In the case of phenanthrolines the alcohol consumption was lower than with oxygen but some catalysis did take place. Therefore the effect of the phenanthrolines in oxygen delignification would result from the catalysis of both oxygen and hydrogen peroxide reactions with lignin. The experiments conducted on veratryl alcohol and on a native lignin containing substrate showed that phenanthroline based complexes were the most active complexes. However the use of a fully bleached pulp regarded as cellulose model indicated that they also damaged cellulose. As a consequence, these catalysts are non selective to lignin limiting their interest for oxygen bleaching. But other applications, like oxygen pulping for the production of high kappa number pulp may be envisaged.
oxidation oxygen catalysis native lignin polypyridinyl complexes
Nathalie Marlin Basile Gueneau Matilte Halma Dominique Lachenal Alain Deronzier Fabrice Thomas
LGP2-Pagora, UMR 5518, 461 rue de la Papeterie, BP 65, 38402 St Martin dH(e)res cedex, France D(e)partement de Chimie Mol(e)culaire, Equipe Chimie Inorganique R(e)dox, Universit(e) Joseph Fourie
国际会议
16th International Symposium on Wood,Fiber and Pulping Chemistry(第十六届木材、纤维及制浆化学国际会议)
天津
英文
218-222
2011-06-08（万方平台首次上网日期，不代表论文的发表时间）