Structural study of mesoporous titania prepared from titanium alkoxide andcarboxylic acids

Mesoporous titania with regulated pore size as well as high specific surfac e area was prepared from titanium alkoxide and various carboxylic acids wit h different alkyl-chain length [CH3(CH2)(n)COOH : n = 0-20]. Although the p ore size and pore volume of titania changed slightly at n < 10, they increa sed with increasing the alkyl-chain length of carboxylic acid at n greater than or equal to 10. Each carboxylic acid forms a complex with titanium alk oxide in an organic-inorganic precursor, while the precursor prepared by us ing carboxylic acid with n greater than or equal to 10 consists of a lamell a-type mesophase. The interplanar distance of the lamella structure increas es with increasing the alkyl-chain length of carboxylic acid. During calcin ation, the lamella structure collapses together with the combustion of orga nic moieties and titania particles crystallized to anatase aggregate to pro vide pores. Although carboxylic acid does not act as a true template, the f ormation of the lamella-type mesophase in the precursor plays an important role in controlling the pore size of titania.