Preparation and characterization of sol-gel derived mesoporous titania spheroids

The formation of mesoporous spherical titania particles via hydrolysis of p ure titanium tetra-isopropoxide in n-heptane solution upon the application of a slow stirring rate is described. Calcination of the dry hydrolysis pro duct 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 deg reesC. Upon calcination at 600 degreesC, the pore size remained at 10 nm, w hereas the S-BET value was decreased. The material calcined at 400 degreesC was found by scanning electron microcopy to be shaped into spherical parti cles about 2 mum in diameter. Sizes of the spherical particles were unchang ed at 400 degreesC and up to 800 degreesC. This was ascribed to the spheric al morphology of the particles which prevented primary particles from growi ng beyond the boundary of the host aggregate even when the rutile phase tra nsition occurred at 800 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.