Factors affecting the preparation of ordered mesoporous ZrO2 using the replica method

Abstract

SBA-15 was employed as the hard template in the preparation of ordered mesoporous ZrO₂ by the replica method. The resultant ZrO₂-SR product was characterized by XRD, TEM, EDX, SEM and nitrogen physisorption. The starting material, intermediate and product were studied by FT-IR. The formation of Zr–O–Si crosslinks made it impossible to obtain a pure ZrO₂ product, although the material did have a similar ordered mesoporous structure to the SBA-15 template. The results showed that the replica method itself could be successfully used to prepare ordered mesoporous ZrO₂, but that the use of mesoporous silica as the hard template meant that the silicon could not be completely removed from the product. The product was seen to contain both the normally stable monoclinic form of zirconia as well as the metastable tetragonal phase. The presence of the latter was considered to be related to the constriction of particle size by the SBA-15 template and by the Si-containing surface layer. These could both hinder sintering of the zirconia particles and prevent crystallite growth to sizes above the critical size, where the tetragonal phase would not be expected. The mesoporous zirconia product had a specific surface area of 220 m² g⁻¹ and a pore volume of 0.57 cm³ g⁻¹, making it of great interest for applications as a support in catalysis and electrocatalysis.