Control of micropore size in supermicroporous titania–chromia system TiO2–Cr2O3

Sol–gel hydrolysis reactions of titanium(IV) isopropoxide and chromium (III) acetate hydroxide in the presence or absence of propanol, using the following amines as structure directing agents; N-hexylamine, N-methylhexylamine, and N-propylbutylamine, yielded microporous mixed metal oxides with the presence of pores largely in the 10–20 Å region, and surface areas that vary from 564 m2/g when N-hexylamine is employed as pore directing template to 494 m2/g when N-propylbutyl amine is employed as template. The maxima in pore size distribution increases with increase in steric crowding around the nitrogen in the alkyl amine. In addition, the nitrogen adsorption–desorption isotherm shifted from Type 1 isotherm when N-hexylamine is used as templating agent to Type 4 isotherm in N-propylbutylamine.