Engineering of silica-supported platinum catalysts with hierarchical porosity combining latex synthesis, sonochemistry and sol-gel process – I. Material preparation

A novel catalyst preparation procedure is proposed in order to enhance the noble metal distribution at low loadings, while controlling the hierarchical porosity of the support material. Thus, a silica-supported platinum catalyst with hierarchical porosity was prepared using a combination of three processes performed in aqueous medium: emulsion polymerisation, sonochemistry and sol-gel synthesis. First, a polystyrene latex template of ca. 130 nm was synthesised by emulsion polymerisation and subsequently decorated with Pt nanoparticles of ca. 2.1 nm by sonochemical reduction of sodium tetrachloroplatinate. Then, the mesoporous silica support was prepared by a two-step acid-base catalysed sol-gel synthesis around the Pt-loaded latex spheres. Materials with specific surface areas and total pore volumes as high as 615 m² g⁻¹ and 0.74 cm³ g⁻¹, respectively, were obtained.