Preparation of SBA-15 and Zr-SBA-15 materials by direct-synthesis and pH-adjustment methods

Abstract

SBA-15 mesoporous silica materials with zirconium atoms incorporated into its structure were prepared by two methods: direct-synthesis and pH-adjustment. Two nominal ratios of Zr/Si = 0 and 0.10 were evaluated. N2-physisorption, X-ray powder diffraction (XRPD) and, X-ray Photoelectron Spectroscopy (XPS) revealed that the morphology and structural order of the SBA-15 materials were greatly affected by the partial incorporation of zirconium into the SBA-15 structure as well as by the synthesis method. High-resolution transmission electron microscopy (HRTEM) of the materials prepared by pH-adjustment (SBA-15-2 and Zr-SBA-15-2 samples) revealed a more perfectly defined mesoporous structure with long-range ordering when compared with the materials obtained by direct-synthesis (SBA-15-1 and Zr-SBA-15-1 samples). The results by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Energy-Dispersion X-ray Spectroscopy (EDX) to evaluate the elemental composition of the materials indicated a better correlation using the pH-adjustment method.