Rutile Formation in Hydrothermally Crystallized Nanosized Titania

Abstract

The present study shows that peptization aids in the anatase‐rutile transformation in hydrothermally processed (250°C, 4000 kPa) titania sols produced by the hydrolysis of alkoxide. HREM images show the presence of nanocrystals of 25–55 nm size. The anatase‐rutile phase transformation in peptized titania is critically dependent on the conditions of hydrolysis such as the water/alkoxide concentration ratio and the size of the alkoxide. Hydrolysis of the ethoxide gave rise to a predominantly rutile phase whereas the isopropoxide and butoxide resulted in a predominantly anatase powder, under the same conditions of treatment. BET surface areas decrease from 107.1 to 68 m 2 /g when the alkoxide is changed from tert ‐butoxide to ethoxide for a given water/ alkoxide ratio.