Lignin reactions in oxygen delignification catalysed by Mn(II)-substituted molybdovanadophosphate polyanion
authors Gaspar, A; Evtuguin, DV; Neto, CP
nationality International
journal HOLZFORSCHUNG
author keywords delignification; lignin; oxidative catalysis; oxygen; polyoxometalate
keywords MODEL COMPOUNDS; WOOD LIGNIN; KRAFT PULP; PART II; DEGRADATION; OXIDATION
abstract The lignin oxidation in the oxygen delignification/bleaching process catalysed by Mn(II) substituted heptamolybdopentavanadophosphate polyanion (HPA-5-Mn-II) was studied using monomeric lignin model compounds and Eucalyptus globulus dioxane lignin adsorbed on the bleached sulphite pulp. The analysis of reaction products after lignin models oxidation in the presence HPA-5-Mn-II and the parent heptamolybdopentavanadophosphate polyanion (HPA-5) showed similar qualitative and quantitative patterns, indicating the identical lignin oxidative delignification mechanisms with both catalysts. The higher delignification selectivity of the pulp in the reaction system HPA-5-Mn-II/O-2 than with HPA-5/O-2 was explained by the protective effect of Mn-II in the heteropolyanion towards oxidative degradation of polysaccharides. The study of lignin adsorbed on bleached sulphite pulp, in the HPA-5-Mn-II/O-2 delignification system, showed the cleavage of beta-O-4 linkages as the major contribution to the lignin depolymerisation. The formation of Calpha-O-polysaccharide linkages in beta-O-4 structures of lignin during the delignification was observed.
publisher WALTER DE GRUYTER & CO
issn 0018-3830
year published 2004
volume 58
issue 6
beginning page 640
ending page 649
digital object identifier (doi) 10.1515/HF.2004.118
web of science category Forestry; Materials Science, Paper & Wood
subject category Forestry; Materials Science
unique article identifier WOS:000224277300009
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journal impact factor 1.826
5 year journal impact factor 1.828
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