Creation of Pd/Al₂O₃ Catalyst by a Spray Process for Fixed Bed Reactors and Its Effective Removal of Aqueous Bromate

Palladium nanoparticles were grown on sub-millimeter activated Al₂O₃ particle support by spraying H₂PdCl₄ solution evenly onto the support, followed with a thermal reduction under H₂ atmosphere. Compared with its counterpart created by the conventional impregnation method, the Pd/Al₂O₃ catalyst created by the spray process could enrich the existence of active Pd nanoparticles on the surface of the catalyst support and increase their degree of dispersion, resulting in a much higher activity in the catalytic reduction of bromate in water. The effect of Al₂O₃ support particle size on the bromate removal rate was also investigated, which demonstrated that smaller support particle size could have higher activity in the catalytic reduction of bromate in water because of its larger exposed surface. This Pd/Al₂O₃ catalyst could be easily used in the fixed bed reactor due to its large support size and demonstrated excellent stability in the catalytic reduction of bromate in mineral water. This Pd/Al₂O₃ catalyst also exhibited a good catalytic reduction performance on azo dyes as demonstrated by its effective catalytic hydrogenation of methyl orange. Thus, catalysts prepared by the spray method developed in this work could have the potential to be used in fixed bed reactors for various water treatment practices.