Oxidative delignification of wood or wood pulp by transition metal-substituted polyoxometalates

A method for delignifying wood comprising the steps of:

• obtaining a sample of wood fibers;
• and
• contacting the wood fibers with a solution of a polyoxometalate of the formula [V.sub.l Mo.sub.m W.sub.n Nb.sub.o Ta.sub.p (TM).sub.q X.sub.r O.sub.s ].sup.x- where l is 0-18, m is 0-40, n is 0-40, o is 0-10, p is 0-10, q is 0-9, r is 0-6, TM is a d-electron-containing transition metal ion, and X is a heteroatom, which is a p or d block element, where l+m+n+o+p.gtoreq.4, l+m+q>0 and s is sufficiently large that x>0, under conditions wherein
• said polyoxometalate solution is 0.001 to 0.20M;
• the pH of said solution is adjusted to 1.5 or higher;
• the consistency of said wood fibers and said polyoxometalate solution is approximately 1 to 20%;
• said mixtures are heated in a sealed vessel under conditions of temperature and time wherein the polyoxometalate is reduced and enhanced delignification occurs.

A method for delignifying lignocellulosic fibers comprising the steps of:

• obtaining a sample of lignocellulosic fibers;
• and
• contacting the lignocellulosic fibers with a solution of a polyoxometalate of the formula [V.sub.l Mo.sub.m W.sub.n Nb.sub.o Ta.sub.p (TM).sub.q X.sub.r O.sub.s ].sup.x- where l is 0-18, m is 0-40, n is 0-40, o is 0-10, p is 0-10, q is 0-9, r is 0-6, TM is a d-electron-containing transition metal ion, and X is a heteroatom, which is a p or d block element, where l+m+n+o+p.gtoreq.4, l+m+q>0 and s is sufficiently large that x>0, under conditions wherein
• said polyoxometalate solution is 0.001 to 0.20M;
• the pH of said solution is adjusted to 1.5 or higher;
• the consistency of said lignocellulosic fibers and polyoxometalate solution is approximately 1 to 20%;
• said mixtures are heated in a sealed vessel under conditions of temperature and time wherein the polyoxometalate is reduced and enhanced delignification occurs.

A method for delignifying lignocellulosic pulps comprising the steps of:

• obtaining a sample of lignocellulosic pulp;
• and
• contacting the lignocellulosic pulp with a solution of a polyoxometalate of the formula [V.sub.l Mo.sub.m W.sub.n Nb.sub.o Ta.sub.p (TM).sub.q X.sub.r O.sub.s ].sup.x- where l is 0-18, m is 0-40, n is 0-40, o is 0-10, p is 0-10, q is 0-9, r is 0-6, TM is a d-electron-containing transition metal ion, and X is a heteroatom, which is a p or d block element, where l+m+n+o+p.gtoreq.4, l+m+q>0 and s is sufficiently large that x>0, under conditions wherein
• said polyoxometalate solution is 0.001 to 0.20M;
• the pH of said solution is adjusted to 1.5 or higher;
• the consistency of said lignocellulosic pulp and said polyoxometalate solution is approximately 1 to 20%;
• said mixtures are heated in a sealed vessel under conditions of temperature and time wherein the polyoxometalate is reduced and enhanced delignification occurs.