Pd-based catalysts for catalytic wet oxidation of combined Kraft pulp mill effluents in a trickle bed reactor

Abstract

Catalytic wet oxidation of combined pulp mill effluents was studied in a trickle bed reactor. Two types of supported Pd-based catalysts, eggshell and uniform catalysts, and a supported Pd–Pt uniform catalyst were employed. Supported Pd catalysts showed high activity for total organic carbon (TOC) and color removal at temperatures of 353–448 K and 1.84 MPa. Compared to uniform catalysts, the eggshell catalysts with a 0.2 wt.% Pd loading show promise for treatment of combined pulp mill effluents. High activity for TOC and color removal can be attributed to the high density of active Pd sites in the shell area and to the decrease of diffusion path for reactants and intermediates. No apparent deactivation of eggshell catalysts was observed after 40 h on stream. Potential application of the supported Pd catalysts for treatment of combined pulp mill effluents is discussed.