The key to control Cu II loading in silica based mesoporous materials

Cu II loading on porous silica surfaces has been shown in the past to be easy to perform but no precise control on the amount of copper loaded has been elucidated. Here, controlled Cu II loading can be accomplished at ambient temperature in a reaction time of 10 min for loadings of 6-20% Cu (w/w). Analysis by UV-visible spectroscopy of copper uptake in SBA-15 materials has shown that the pH of the solution and the consequent complexation of the Cu II cation dictates the amount of Cu (II) impregnation. The key to the success of this control is the presence of the [Cu(NH₃)₃(H₂O)₃]²⁺ complex in the reaction solution. FT-IR, diffuse reflectance UV-visible spectroscopy, N₂ adsorption, TEM (transmission electronic microscopy) and SAXS (small angle X-ray scattering) analyses were performed on the obtained SBA-15 Cu materials illustrating a well dispersed Cu (II) covering of the SBA-15 surface.