Study On The Controllable Preparation Of Mesoporous Titania And The Catalytic Performance Of Au/M-TiO₂ For CO Oxidation

Au/TiO₂ has shown an inconceivable activity for CO oxdiation, but it will deactivate after sintering at high temperature. Industrial application of Au/TiO₂ was non-ideal due to the low reproducibility and instable effect. Au catalysts were prepared by the DP method, and Au nanoparticles can be highly dispersed on the surface of mesoporous titania, thus reducing the high temperature process due to the growth of Au nanoparticles caused the derease of activity and increased the stability of Au catalyst. In the work, we demonstrated a hard/soft templates method and the high surface area ?>3OOm²/g? of mesoporous TiO₂ were obtained after the removal of carbon and silicon. The Au catalysts prepared by the DP method and the activity tested with different-pretreatment. The main research results:?1? Using fresh TiCl₄ solution as a titania source, TEOS as a silica source, RESOL as a carbon source, and F127 as a template, we could successfully synthesize a series of highly ordered mesoporous TiO2/SiO2/C composites via an ethanolic EISA process. After removing carbon and silica, the pure mesoporous titania are obtained ?300 m²/g?. Its surface area is the largest of literature reports. Furthemore, we put forward the new formation mechanism of mesoporous TiO2.?2? Au was loaded on the mesoporous TiO₂ via a DP method. A series of Au/TiO₂ catalysts were prepared ?0.2wt%-4wt%?. 1wt% Au/M-TiO₂ exhibits the activity with T50%?temperature of 50% CO conversion? of 32? and after sintering of 600? with T50%= 45?. As a result of high-temperature ?600?? sintering, the average size of the Au nanoparticles reaches 3-5 nm. Comparing with 300?-pretreatment, Au grew a little and dispersed well. The catalytic activity of 1 wt% Au600 displays a dramatic stability at more stringent conditions ?4%CO,100 ml/min?,95% CO conversion can be kept after 120 h of reaction without decays. The catalyst shows high sintering resistance and good catalytic stability.?3? In order to get a higher catalytic activity of gold catalysts, we doped Zn modified mesoporous titania. We prepared TiO2/ZnO mesoporous composites via coprecipitation and co-synthesis method. The results show that the TiO2/ZnO mesoporous composites via co-synthesis method have a higher catalytic activity. The 1wt% Au/ZnO-TiO₂ exhibits the activity with T50% of -10? and the stability of keeping conversion of 90% about 25h. Comparing with The catalytic performance of Au/TiO2, the catalytic Activity increased with the stability decreased.