Structural Study of Mesoporous Titania Prepared from Titanium Alkoxide and Carboxylic Acids

Mesoporous titania with regulated pore size as well as high specific surface area was prepared from titanium alkoxide and various carboxylic acids with different alkyl-chain length CH₃(CH₂) _n COOH : n = 0–20]. Although the pore size and pore volume of titania changed slightly at n < 10, they increased with increasing the alkyl-chain length of carboxylic acid at n 10. Each carboxylic acid forms a complex with titanium alkoxide in an organic-inorganic precursor, while the precursor prepared by using carboxylic acid with n 10 consists of a lamella-type mesophase. The interplanar distance of the lamella structure increases with increasing the alkyl-chain length of carboxylic acid. During calcination, the lamella structure collapses together with the combustion of organic moieties and titania particles crystallized to anatase aggregate to provide pores. Although carboxylic acid does not act as a true template, the formation of the lamella-type mesophase in the precursor plays an important role in controlling the pore size of titania.