Preparation and characterization of sol-gel derived mesoporous titania spheroids

The formation of mesoporous spherical titania particles via hydrolysis of pure titanium tetra-isopropoxide in n-heptane solution upon the application of a slow stirring rate is described. Calcination of the dry hydrolysis product produced pure anatase at 400-600 degreesC, and rutile at 800 degreesC. Nitrogen adsorption results indicate high surface area (S-BET 132 m(2)/g) and uniform mesopores peaking at 10 nm for the material calcined at 400 degreesC. Upon calcination at 600 degreesC, the pore size remained at 10 nm, whereas the S-BET value was decreased. The material calcined at 400 degreesC was found by scanning electron microcopy to be shaped into spherical particles about 2 mum in diameter. Sizes of the spherical particles were unchanged at 400 degreesC and up to 800 degreesC. This was ascribed to the spherical morphology of the particles which prevented primary particles from growing beyond the boundary of the host aggregate even when the rutile phase transition occurred at 800 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.