6º Congresso Florestal Nacional, Ponta Delgada, Portugal - 2009 NEW HIGHLY EFFICIENT METHOD OF POLYOXOMETALATE (POM) CATALYZED OZONE BLEACHING OF INDUSTRIAL EUCALYPT (E. globulus) KRAFT PULP Anatoly A. Shatalov ∗ and Helena Pereira Centro de Estudos Florestais, Universidade Técnica de Lisboa, Institute Superior de Agronomia, 1349-017 Tapada da Ajuda, Lisboa, Portugal Abstract The highly efficient and selective environmentally benign bleaching approach using polyoxometalate (POMs) catalyzed ozonation of chemical pulps in organic solvent reaction media has been developed. The Keggin-type molybdovanadophosphate heteropolyanions (HPAs) showed a well-defined capacity for ozonation improvement in the presence of number polar low-boiling aprotic and protic organic solvents. Under optimized conditions, the solvent-based HPA-catalyzed ozone bleaching of industrial eucalypt kraft pulp showed remarkable brightness improvement by 15.1% ISO, with additional lignin removal by 39.4% and increase in intrinsic viscosity by 3% in comparison with conventional ozone bleaching technique. Introduction The environmental concern related to pollutant commercial chlorine-based pulp bleaching technologies along with the increased market demand for totally chlorine-free (TCF) and low AOX (absorbable organic halogens) pulps caused substantial interest to non-chlorine oxidative bleaching chemicals such as oxygen, hydrogen peroxide and ozone. Ozone is the most powerful and particularly potential oxidation agent for chemical pulp bleaching [1]. However, the low selectivity of ozone treatment towards lignin (due to unwanted reactions with carbohydrates) restricts delignification capacity of ozone and limits substantially its further commercialization [2]. The selectivity improving of ozone bleaching can be solved by use of efficient catalytic systems such as polyoxometalates (POMs), which have a wide application as versatile green catalysts for liquid-phase oxidation of different organic substances [3]. Heteropolyoxometalates (free acids and salts of heteropolyanions) possessing the properties of both strong acids and very efficient oxidants hold a great interest now for application like * Corresponding author. Phone: +351-213634662 Fax: +351-213645000 E-mail: anatoly@isa.utl.pt (Dr. A.A. Shatalov)