Copper nanoparticles as active catalysts in hydroxylation of phenol by hydrogen peroxide

Copper nanoparticles have been found to be catalysts for both homogeneous (stabilized by oligoethyleneglycols) and heterogeneous (immobilized on SiO2) hydroxylation of phenol by hydrogen peroxide to dihydroxybenzenes. The catalysts were synthesized in oligoethyleneglycols by the reduction of copper salts (supported or nonsupported) using hydrazine. For non-immobilized Cu-nanoparticles high selectivities on dihydroxybenzenes were reached at the conversion of phenol 32% for 30 min at 40 °C. It has been demonstrated that adding oxyethylated surfactants to non-immobilized nanoparticles during reaction increased selectivity for the ortho-product. Immobilized Cu-nanoparticles allowed to achieve the conversion of 69% for 15 min at 70 °C with selectivity on dihydroxybenzenes more than 95%.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (43 K)Download as PowerPoint slideResearch highlights▶ Copper nanoparticles catalyzed phenol hydroxylation by hydrogen peroxide. ▶ Selectivity for the ortho-product increases by adding oxyethylated surfactants. ▶ Copper nanoparticles immobilized on silica demonstrate highest activity.