Preparation of Pd/SiO 2 catalysts for methanol synthesis I. Ion exchange of [Pd(NH 3) 4)(AcO) 2

Abstract

An in-depth analysis of the adsorption via ion exchange (IE) of aminepalladium complexes prepared from palladium acetate on well-characterized commercial gels of silica (Davison, G-59 and G-03) in aqueous alkaline solutions is carried out. The nature of the exchanged species after different IE and washing treatments is scrutinized with diffuse reflectance spectroscopy. It is shown that (i) there is a maximum of IE at pH 10.3; (ii) IE occurs without any exchange of ligands; (iii) adsorption equilibrium is reached in about 1 h and (iv) IE follows a common Frumkin isotherm on both supports.