Figure 1.

Representation of the pore structure of the materials. (a) Zeolite 4A structure with eight-ring pore opening of about 0.4 nm composed of Al (blue) and Si (purple) tetrahedra connected by O, (b) ETS-4 structure with eight-ring pore opening of about 0.4 nm composed by Si (purple) tetrahedra and Ti (green) octahedra (one oxygen on the vertical octahedra corresponds to water that can be removed to obtain pentacoordinated Ti) and (c) ETS-10 structure with 12-ring pore opening of about 0.8 nm composed by Si (purple) tetrahedra and Ti (green) octahedra. In the case of Co-ETS-4 the extra-framework cations were replaced by Co and in the case of ETAS-10 some Si was replaced by Al, but the structure is analogous to ETS-10. Colour code: Si purple, Ti green, Al blue, O red and cations in yellow. Note: materials labelled ETS are types of titanosilicates.