Mesoporous silicate (MCM-41) materials, modified with CuII, FeIII or AlIII were prepared by a hydrothermal method and were characterized by nitrogen adsorption at 77 K, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), temperature programmed reduction (TPR), adsorption of pyridine as monitored by Fourier transform infrared spectroscopy (FTIR) and n-butylamine titration. The degree of ordering of the mesoporous material was decreased by the presence of Cu, Fe, or Al. The added Fe or Cu gave rise to new acidic and oxidation-reduction sites, while Al resulted in new acidic sites. The hydrothermal stabilities of selected samples were studied as a function of temperature and pH. All the samples were stable in acidic and neutral media at temperatures from 303 to 363 K. Adsorption of phenol on MCM-41 at 303 K was strongly influenced by the pH and by the modification with Cu, Fe, or Al. Phenol adsorption was particularly strong at the Al-modified material at pH 3, apparently due to the acidic character of phenol.
Keywords
MCM-41; metal modification; aqueous stability; phenol adsorption
