Characterization of Ti-Beta zeolites and their reactivity for the photocatalytic reduction of CO2with H2O

Keita Ikeue, Hiromi Yamashita, Takahiko Takewaki, Mark E. Davis, Masakazu Anpo
2001 Journal of Synchrotron Radiation  
A characterization of Ti-Beta zeolites synthesized under various conditions as well as an investigation of their photocatalytic properties for the reduction of CO 2 with H 2 O at 323 K to produce CH 4 and CH 3 OH were carried out. In situ XAFS spectra measurements indicated that a highly dispersed tetrahedral titanium oxide species was present in the zeolite framework and an increase in the coordination number of the titanium oxide species by the addition of H 2 O and CO 2 molecules could be
more » ... ected. The Ti-Beta zeolite having a hydrophilic property ( Ti-Beta(OH) ) exhibited a more dramatic increase in the coordination number than the Ti-Beta(F) zeolite which had a hydrophobic property. These results suggest that CO 2 and H 2 O molecules can be adsorbed efficiently onto the highly dispersed tetrahedrally coordinated titanium oxide species. UV irradiation of these Ti-Beta zeolite catalysts in the presence of H 2 O and CO 2 led to the formation of CH 4 and CH 3 OH. Ti-Beta(OH) exhibited a higher reactivity than Ti-Beta(F), while the selectivity for the formation of CH 3 OH on Ti-Beta(F) was higher than that for Ti-Beta(OH). These results indicated that the reactivity and selectivity of the zeolite catalyst can be determined by the hydrophilic and hydrophobic properties of the zeolites.
doi:10.1107/s0909049500014394 pmid:11512865 fatcat:t2e5kwto7vekhcue33jzlgitcm