Synthesis and properties of stannosilicates

The stannosilicates (MFI) containing either Sn(II) or Sn(IV) were prepared by means of hydrothermal crystallization. The high crystalline MFI structure was obtained for various Sn/Si ratios up to the value of 0.05, while the further increase in Sn loading resulted in amorphous products. The stannosilicates (II) showed some ion-exchange ability and could be modified with various cations (e.g. Cu2+ and H+). Their H-forms showed considerable activity in propan-2-ol dehydration, whereas the Sn(IV)-MFI were inactive in this reaction. Both series showed catalytic activity for 2-methyl-3-butyn-2-ol decomposition, but selectivity depended on valence of Sn and on kind of introduced cations (in the case of the Sn(II) series). In cyclohexene oxidation the samples Sn(IV)-MFI showed remarkable activity, contrary to the Sn(II) series. Nevertheless, the latter indicated some oxidation activity after modification with Cu2+ cations.