Recycled TiO2 from the deactivated SCR catalysts for the CaCO3-TiO2 composite opacifier and its function in the zirconium-free glaze system

Abstract

A CaCO3-TiO2 composite (CaCO3-SCR) was prepared by a facile mechanochemistry method using CaCO3 and TiO2 from the deactivated SCR catalysts. The results show that the CaCO3-SCR composite as opacifiers exhibits excellent opacifying performance. The FT-IR results indicate that -Ca-O-Ti- bonds existing between CaCO3 and TiO2 from the deactivated SCR catalysts combine them. The main opacifying phase is the sphene phase with particles size about 0.5–1 μm. Moreover, no excess crystalline TiO2 was observed in the glaze, indicating that fixing TiO2 is the key to preventing glaze from yellowing.