THE PHOTOCATALYTIC CONVERSION OF CO2 INTO HYDROCARBONS OVER CATALYST CENTERS IN MESOPOROUS SILICAS

摘要

Highly dispersed tetrahedrally coordinated Ti species incorporated in silica are efficient for photocatalytic reduction of CO2 by water vapour [1]. In application of a Ti-functionalized 2D mesoporous material SBA-15 [2], hydrocarbons such as methane, ethane and ethene have been detected, all be it at low concentrations. In the presentation several strategies for improvement of the activity of Ti-functionalized SBA-15 based catalysts will be presented. First, the accessibility of the mesoporous network will be demonstrated to affect the performance. A 1% Ti loading was found to be more effective (30- 35%) for the siliceous 3D mesoporous material TUD-1 [3], as compared to SBA-15. The 3D open structure of TUD-1 probably increases the accessibility of reactants to the Ti active sites. Characterization results indicate the presence of Ti in the form of isolated centers [(-Si-O)_3-Ti-O-] in both catalysts. These were previously reported to be essential for a high activity per Ti-site [1]. The stability of both catalysts was high.