Catalytic Delignification of Cellulose Half-Stuff by Molecular Oxygen Using Polyoxometalates as a Catalysts

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676.023.11:544.478

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Abstract

The two stages catalytic delignification of hardwood and softwood cellulose fiber were researched. The first step was catalytic oxidative delignification of cellulose half-stuff by molecular oxygen with polyoxometalates (molybdovanadophosphate polyoxoanion and Mn-assisted molybdovanadophosphate polyoxoanion). On the second step alkali treatment was carried out to improve of process efficiency and removal of lignin from the oxidized cellulose fiber surface. Influence of the nature and concentration of catalyst, temperature and pH on parameters such as the Kappa number, the whiteness, the viscosity and the degree of polymerization was studied. It was found out that the delignification of cellulosic fibers is intensified with the polyoxometalates HPA -5 and HPA -5-Mn. The HPA -5-Mn catalyst is more selective then HPA -5. The most changing of the Kappa number is observed at the concentration of catalyst 2.0 mmol / l, that is 20% of the weight of absolutely dry pulp. Further increasing the concentration doesn’t have significantly influence on the process. pH ranging from 2 to 4 has little effect on the catalytic delignification process as hardwood and softwood pulps. The effectiveness of the process may be significantly increased by the raising temperature and introduction of additional alkali extraction stage.

Authors

T.V.Tortseva, Candidate of Chemistry, Associate Professor N.R.Popova, Candidate of Chemistry, Professor K.G.Bogolitsy, Doctor of Chemistry, Professor Northern (Arctic) Federal University named after M.V. Lomonosov Naberezhnaya Severnoy Dviny, 17, Arkhangelsk, 163002, Russia E-mail: b.mochalov@narfu.ru

Affiliation

Northern (Arctic) Federal University named after M.V. Lomonosov

Keywords

catalytic delignification, cellulose, catalytic oxidation, oxygen, polyoxometalates.

References

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