Titania: From a waste solid catalyst to an inorganic pigment

Abstract The aim of the present study is to recover a waste titania catalyst from α‐pinene isomerization, recycle it and use it in the production of inorganic pigments. The acid‐contaminated titania (ACT), prepared from ilmenite ore by sulphation, has the potential to function as a solid acid catalyst due to the presence of both Brønsted and Lewis acid sites, with a specific surface area of 163 m 2 g −1 . The catalytic efficiency was evaluated in the isomerization of turpentine (83.8 wt.% α‐pinene) at a reaction temperature of 120°C, using a turpentine:catalyst mass ratio of 4:1. The α‐pinene conversion was 99.6% with a camphene selectivity of 43 wt.%. The waste catalyst was recovered and subjected to calcination at a suitable temperature to remove all organic compounds and make it suitable for use in the production of inorganic pigments. The calcined product exhibits pigment properties including a pure rutile phase, an average grain size of 0.2 μm, a specific surface area of 29 m 2 g −1 and a reflectance in visible light of 95%. This study has provided a practical, simple, and cost‐effective solution for the treatment of residual acid on titania obtained from the hydration of titanyl sulphate, while also demonstrating the simultaneous application of titania in catalysis and pigment production.