Dv. Evtuguin et al., OXIDATIVE DELIGNIFICATION IN THE PRESENCE OF MOLYBDOVANADOPHOSPHATE HETEROPOLYANIONS - MECHANISM AND KINETIC-STUDIES, Applied catalysis. A, General, 167(1), 1998, pp. 123-139
The catalytic effect of molybdovanadophosphate heteropolyanions (HPAs)
on the delignification of wood by oxygen has been investigated. The V
O(?)2 ions produced via the dissociation of HPA in acidic conditions a
re suggested to have a much stronger catalytic effect on the oxidation
of lignin than parent HPA. The influence on delignification of the pH
, medium composition and the partial reduction of HPA prior to its use
in catalysis are discussed in terms of the reaction mechanisms. Kinet
ic studies show that the catalyst diffusion in the wood tissue is the
rate-limiting step of delignification, while the lignin oxidation rate
is determined by the HPA/VO2+ catalytic oxidation step. (C) 1998 Else
vier Science B.V.