Efficient liquid-phase hydrogenation of bromate over nanosized Pd catalysts supported on TpBD-Me2 covalent organic framework

The formation of toxic and carcinogenic bromate, BrO3-, during the disinfection of fresh or seawater by ozonation poses a threat to the human health, and therefore the development of methodologies for its removal from water is of high importance. Heterocatalytic bromate hydrogenation has been widely employed to decrease the BrO3- ion concentration in water below the strict legal limit imposed. In this work, we evaluate for the first time the performance of a covalent organic framework (COF) for this reaction.TpBD-Me2 COF was synthesized on gram scale and used as both catalyst and support for Pd nanocatalysts with different Pd loadings for bromate hy-drogenation reaction. TpBD-Me2 was found to present considerable catalytic activity for BrO3- reduction with 60% conversion after 180 min. The conversion increased with increasing Pd loading of the COF, with the sample with 5% Pd on COF reaching 93% conversion after 180 min. The catalytic activity was further improved by performing an in situ pre-reduction step before the reaction, resulting in complete conversion of BrO3- already after 60 min of reaction. These results show that COF materials are efficient catalysts for this application.