Salen copper (II) complex encapsulated in Y zeolite: An effective heterogeneous catalyst for TCF pulp bleaching using peracetic acid

Cu(salen) and NaY encapsulated complexes, were synthesized by the “impregnation” (Cu(salen)/Y-IM) and flexible ligand “ship-in-a-botttle” (Cu(salen)/Y-SB) method. The resulting compounds were characterized by XRD, FTIR, DR UV–vis, BET. The encapsulated complexes show structural properties and chemical behaviour which is different from those of the neat complex. The catalytic bleaching by Cu(salen) and encapsulated Cu(salen) was tested for the eucalyptus oxygen delignified kraft pulp using peracetic acid as an oxidant. Influence of catalysis on TCF (total chlorine free) bleaching viz. delignification, property of bleached pulp was studied. Under the catalytic conditions, the encapsulated copper complexes exhibit enhanced activity or selectivity compared to the neat complex. The reasons for the enhanced activity of Cu(salen) upon encapsulation in NaY are reported by UV–vis techniques. The catalytic performance of encapsulated complex could be attributed to the formation of copper–hydroperoxide species.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (106 K)Download as PowerPoint slideHighlights► Encapsulated Cu(salen) plus CH3COOOH as catalytic system. ► Catalytic system for TCF bleaching of eucalyptus pulp. ► Encapsulated Cu(salen) complexes exhibit enhanced activity or selectivity. ► Reasons for enhanced activity upon encapsulation are reported by UV–vis techniques.