CATALYTIC OXYGEN BLEACHING OF WOOD PULP WITH METAL PORPHYRIN AND PHTHALOCYANINE COMPLEXES

A series of porphyrin and phthalocyanine complexes of Co, Fe, and Mn i s screened for catalytic activity in the oxygen bleaching of unbleache d softwood kraft pulp in 1 M KOH at 25 and 100 degrees C under 0.8 MPa oxygen pressure. The Mn(III) complex of meso(tetrasulfonatophenyl) po rphyrin, isolated as Na3Mn(TSPP).4H(2)O and abbreviated as Mn(TSPP), i s shown to promote delignification and suppress cellulose degradation in oxygen bleaching. The influence of bleaching time, pH, temperature, oxygen pressure, and Mn(TSPP) charge on catalytic activity is assesse d by factorial and parametric experiments. The Mn(TSPP) is effective a t a minimum concentration of about 0.025 g/L (0.023 x 10(-3) M) and is most beneficial for bleaching rate and selectivity in 1 M KOH at high temperature and oxygen pressure (100 degrees C, 0.8 MPa O-2).