Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9616771 | Journal of Molecular Catalysis B: Enzymatic | 2005 | 8 Pages |
Abstract
A series of manganese substituted polyoxotungstates, [SiW11MnIII(H2O)O39]5â and [PW11MnIII(H2O)O39]4â, and [SiW11VVO40]5â were applied as catalysts for the oxygen delignification of unbleached eucalypt kraft pulp with laccase of Trametes versicolor. Unlike to modest results obtained in the Laccase-Mediator System (LMS) at 45-60 °C (lignin oxidation and catalyst re-oxidation occurred at the same stage), a sustainable delignification with removal of about 50% of residual lignin was achieved with [SiW11MnIII(H2O)O39]5â and [SiW11VVO40]5â when the kraft pulp treatment was carried out with polyoxometalate at 110 °C (lignin oxidation stage) and with laccase at 45 °C (catalyst re-oxidation stage) in separate stages. The use of [PW11MnIII(H2O)O39]4â in this multi-stage process was limited by the low re-oxidation rate with laccase. The best selectivity on the pulp delignification was found with polyoxoanion [SiW11MnIII(H2O)O39]5â, whereas [SiW11VVO40]5â was the most effective in the oxidative delignification. The influence of process factors on the POMs re-oxidation, such as the amount of laccase, oxygen pressure and temperature is discussed. UV-vis and 51V NMR studies indicated that POMs maintained stable after redox turnovers during the pulp delignification.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Catalysis
Authors
Jose A.F. Gamelas, Ana P.M. Tavares, Dmitry V. Evtuguin, Ana M.B. Xavier,